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BackgroundLenvatinib plus pembrolizumab showed significantly improved progression-free and overall survival outcomes compared with sunitinib in patients with advanced renal cell carcinoma in the CLEAR study (NCT02811861). Here, we used CLEAR data to characterize common adverse reactions (ARs; adverse-event preferred terms grouped in accordance with regulatory authority review) associated with lenvatinib plus pembrolizumab and review management strategies for select ARs.Materials and MethodsSafety data from the 352 patients who received lenvatinib plus pembrolizumab in the CLEAR study were analyzed. Key ARs were chosen based on frequency of occurrence (≥30%). Time to first onset and management strategies for key ARs were detailed.ResultsThe most frequent ARs were fatigue (63.1%), diarrhea (61.9%), musculoskeletal pain (58.0%), hypothyroidism (56.8%), and hypertension (56.3%); grade ≥3 severity ARs that occurred in ≥5% of patients were hypertension (28.7%), diarrhea (9.9%), fatigue (9.4%), weight decreased (8.0%), and proteinuria (7.7%). Median times to first onset of all key ARs were within approximately 5 months (approximately 20 weeks) of starting treatment. Strategies for effectively managing ARs included baseline monitoring, drug–dose modifications, and/or concomitant medications.ConclusionThe safety profile of lenvatinib plus pembrolizumab was consistent with the known profile of each monotherapy; ARs were considered manageable with strategies including monitoring, dose modifications, and supportive medications. Proactive and prompt identification and management of ARs are important for patient safety and to support continued treatment.Clinicaltrials.gov IDNCT02811861

The integration of genomic testing into clinical care enables the use of individualized approaches to the management of rare diseases. We describe the use of belzutifan, a potent and selective small-molecule inhibitor of the protein hypoxia-inducible factor 2α (HIF2α), in a patient with polycythemia and multiple paragangliomas (the Pacak-Zhuang syndrome). The syndrome was caused in this patient by somatic mosaicism for an activating mutation in EPAS1. Treatment with belzutifan led to a rapid and sustained tumor response along with resolution of hypertension, headaches, and long-standing polycythemia. This case shows the application of a targeted therapy for the treatment of a patient with a rare tumor-predisposition syndrome. (Funded by the Morin Family Fund for Pediatric Cancer and Alex's Lemonade Stand Foundation.).

Background This study assessed whether antiangiogenic treatment may potentiate immune checkpoint blockade in patients with advanced renal cell carcinoma. Patients and Methods This was an open-label, two-part, multicenter study involving treatment-naive patients with advanced renal cell carcinoma. Part 1 consisted of a phase I dose escalation and expansion of pazopanib plus pembrolizumab (combination therapy). Cohorts A and B received pazopanib in combination with pembrolizumab, whereas Cohort C received pazopanib monotherapy for 9 weeks before receiving the combination therapy. Part 2 was planned as a randomized three-arm study but was not conducted. Results Overall, 42 patients were enrolled (10 each in Cohorts A and B, 22 in Cohort C). The maximum tolerated dose was not reached and the recommended phase II dose was not declared, as Cohort C was closed early because of safety concerns. The overall response rates were 60% and 20% in Cohorts A and B, respectively. In Cohort C, the overall response rates were 33%, 25%, and 0% in the combination therapy, pembrolizumab monotherapy, and pazopanib monotherapy groups, respectively. The median progression-free survival rates were 21.95 months and 41.40 months in Cohorts A and B, respectively. Grade 3 or 4 adverse events (AEs) were observed in 90% of patients in Cohorts A and B. In Cohort C, the frequencies of grade 3 or 4 AEs, serious adverse events, and AEs leading to dose reduction were typically high in the combination therapy group. Conclusions Despite preliminary signs of efficacy, significant hepatotoxicity was observed in Cohorts A and B. The sequential schedule of pazopanib followed by pazopanib plus pembrolizumab showed reduced hepatotoxicity; however, other safety issues emerged with this approach.

Summary Background Despite advances in the first-line treatment of metastatic renal cell carcinoma (RCC), there is an unmet need for options to address disease progression during or after treatment with immune checkpoint inhibitors (ICIs). Pembrolizumab and lenvatinib are active as monotherapies in RCC; thus, we aimed to evaluate the combination of lenvatinib plus pembrolizumab in these patients. Methods We report results of the metastatic RCC cohort from an open-label phase 1b/2 study of lenvatinib plus pembrolizumab in patients aged at least 18 years with selected solid tumours and an Eastern Cooperative Oncology Group performance status of 0–1. Oral lenvatinib at 20 mg was given once daily along with intravenous pembrolizumab at 200 mg once every 3 weeks. Patients remained on study drug treatment until disease progression, development of unacceptable toxicity, or withdrawal of consent. Efficacy was analysed in patients with clear cell metastatic RCC receiving study drug by previous therapy grouping: treatment naive, previously treated ICI naive (previously treated with at least one line of therapy but not with an anti-PD-1 or anti-PD-L1 ICI), and ICI pretreated (ie, anti-PD-1 or anti-PD-L1) patients. Safety was analysed in all enrolled and treated patients. The primary endpoint was the objective response rate at week 24 per immune-related Response Evaluation Criteria In Solid Tumors (irRECIST) by investigator assessment. This trial is registered with ClinicalTrials.gov ( NCT02501096 ) and with the EU Clinical Trials Register (EudraCT2017-000300-26), and is closed to new participants. Findings Between July 21, 2015, and Oct 16, 2019, 145 patients were enrolled in the study. Two patients had non-clear cell RCC and were excluded from the efficacy analysis (one in the treatment-naive group and one in the ICI-pretreated group); thus, the population evaluated for efficacy comprised 143 patients (n=22 in the treatment-naive group, n=17 in the previously treated ICI-naive group, and n=104 in the ICI-pretreated group). All 145 enrolled patients were included in the safety analysis. The median follow-up was 19·8 months (IQR 14·3–28·4). The number of patients with an objective response at week 24 by irRECIST was 16 (72·7%, 95% CI 49·8–89·3) of 22 treatment-naive patients, seven (41·2%, 18·4–67·1) of 17 previously treated ICI-naive patients, and 58 (55·8%, 45·7–65·5) of 104 ICI-pretreated patients. Of 145 patients, 82 (57%) had grade 3 treatment-related adverse events and ten (7%) had grade 4 treatment-related adverse events. The most common grade 3 treatment-related adverse event was hypertension (30 [21%] of 145 patients). Treatment-related serious adverse events occurred in 36 (25%) patients, and there were three treatment-related deaths (upper gastrointestinal haemorrhage, sudden death, and pneumonia). Interpretation Lenvatinib plus pembrolizumab showed encouraging antitumour activity and a manageable safety profile and might be an option for post-ICI treatment of metastatic RCC. Funding Eisai and Merck Sharp & Dohme.

Background Axitinib plus pembrolizumab showed superior overall survival (OS), progression-free survival (PFS) and objective response rate (ORR) versus sunitinib in a randomised phase III trial in patients with advanced renal-cell carcinoma (RCC). We report long-term efficacy and safety of the axitinib/pembrolizumab from the phase I trial (NCT02133742), after 46–55 months from study initiation (data cut-off date, 23rd July 2019). Methods Fifty-two treatment-naive patients with advanced RCC were treated with oral axitinib 5 mg twice daily and intravenous pembrolizumab 2 mg/kg every 3 weeks. PFS, duration of response (DoR) and OS were summarised using the Kaplan–Meier method. Results At a median follow-up of 42.7 months (95% confidence interval [CI]: 41.1–44.1), median OS was not reached; 38 (73.1%) patients were alive. The probability of being alive at 4 years was 66.8% (95% CI: 49.1–79.5). Median PFS in the overall population was 23.5 months (95% CI: 15.4–30.4). ORR was 73.1%; five patients had complete response. Median DoR was 22.1 months (95% CI: 15.1–34.5). Grade III/IV adverse events (AEs) were reported in 38 (73.1%) patients and 20 (38.5%) discontinued treatment because of AEs: 17 (32.7%) discontinued axitinib, 13 (25.0%) discontinued pembrolizumab, and 10 (19.2%) discontinued both drugs. Common AEs included diarrhoea (84.6%), fatigue (80.8%), hypertension (53.8%), cough (48.1%) and dysphonia (48.1%). There were no new AE terms reported and no treatment-related deaths. Conclusions In patients with advanced RCC with ~4 years of follow-up, combination axitinib/pembrolizumab continued to demonstrate clinical benefit, with no new safety signals.

Background: First-line treatment with immunotherapy alone or in combination with antiangiogenic agents is a standard of care for advanced RCC. Many patients (pts) develop resistance to first-line treatment and effective second-line and beyond options are needed. The von Hippel-Lindau (VHL) gene is inactivated in approximately 90% of RCC cases, which results in the constitutive activation of hypoxia-inducible factor 2α (HIF-2α), a key oncogenic driver in RCC. The first-in-class HIF-2α inhibitor belzutifan has demonstrated promising antitumor activity with manageable safety in previously treated pts with advanced RCC. The cyclin-dependent kinase (CDK) pathway has also been implicated in RCC and is associated with poor clinical outcomes. In RCC cell lines, the CDK 4/6 inhibitor palbociclib inhibited cell growth. The addition of CDK 4/6 inhibition had synergistic antiproliferative effects with HIF-2α inhibition in HIF-2α-dependent VHL -/- RCC cell lines. Palbociclib could therefore potentially enhance the efficacy of belzutifan as combination therapy for previously treated pts with advanced RCC. Methods: The two-part, open-label, multicenter, phase 1/2 randomized LITESPARK-024 study (NCT05468697) is intended to establish the recommended phase 2 dose (RP2D) of belzutifan + palbociclib in combination with a modified toxicity probability interval design (Part 1), followed by a direct comparison of belzutifan monotherapy to the combination with respect to safety and efficacy in pts with advanced RCC (Part 2). Pts with histologically confirmed unresectable stage IV RCC with a clear cell component, whose disease progressed on or after having received at least 2 systemic treatments (both an anti-PD-1/PD-L1 monoclonal antibody and a VEGF receptor-targeted tyrosine kinase inhibitor, in sequence or in combination), have measurable disease per RECIST v1.1 by blinded independent central review, and have KPS score of ≥70% will be enrolled. Up to 30 pts will be enrolled into 3 dose groups in Part 1 and will receive belzutifan 120 mg once daily + palbociclib (75, 100, or 125 mg) daily for 21 consecutive days followed by 7 days off. In part 2, approximately 150 pts will be randomly assigned 2:1 to receive belzutifan 120 mg once daily + palbociclib RP2D (21 consecutive days/7 days off) or belzutifan 120 mg once daily. Pts will be stratified by IMDC risk (0 vs 1-2 vs 3-6) and sarcomatoid histology (yes vs no) at randomization in part 2. The primary end point for part 1 is to assess dose-limiting toxicities and adverse events to determine the RP2D of belzutifan + palbociclib. The primary end point for part 2 is ORR per RECIST v1.1 by investigator assessment. Secondary end points for part 2 are CBR, DOR, PFS, OS, and safety and tolerability. This abstract was accepted and previously presented at the 2023 ASCO Genitourinary Cancers Symposium. All rights reserved. Citation Format: David F. McDermott, Avivit Peer, Neeraj Agarwal, Michael B. Atkins, Jerry Cornell, Rodolfo F. Perini, Kenneth F. Grossmann, Howard Gurney. The randomized phase 1/2 LITESPARK-024 study of belzutifan with or without palbociclib in patients with advanced renal cell carcinoma (RCC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT120.

4514 Background: In the open-label, randomized, phase 3 CLEAR study, LEN + PEMBRO had significant PFS (primary endpoint) and OS (key secondary endpoint) benefits over SUN among pts with aRCC in the 1L setting (Motzer 2021, NEJM). We evaluated PFS on next-line therapy (“PFS2”) and explored the effect of subsequent anticancer therapy on OS in the LEN + PEMBRO and SUN treatment arms of CLEAR. Methods: PFS2 was defined as time from randomization to disease progression (as assessed by investigator) on next-line treatment or death from any cause (whichever occurred first). PFS2 was evaluated in all pts randomly assigned to LEN 20 mg orally QD + PEMBRO 200 mg IV Q3W (n=355) or SUN 50 mg orally QD (4 wks on/2 wks off) (n=357) using Kaplan-Meier estimates, and compared between treatment arms via a log-rank test stratified by geographic region and MSKCC prognostic groups. The HR and corresponding CI were estimated using the Cox regression model with Efron’s method for ties, using the same stratification factors. A post hoc analysis accounting for the effect of subsequent anticancer therapy on OS (time from randomization to death from any cause) in the LEN + PEMBRO and SUN arms using 2-stage estimation was conducted. Results: Among pts who received subsequent anticancer therapy in the LEN + PEMBRO (n=117 pts) and SUN (n=206 pts) arms (Table), median time to next-line therapy was 12.2 mos (range 1.45–37.36) and 6.4 mos (range 0.39–28.52), respectively. Median duration of first subsequent anticancer therapy was 5.2 mos (range 0.10–30.23) in the LEN + PEMBRO arm and 6.8 mos (range 0.03–30.72) in the SUN arm. Among all pts, PFS2 was longer with LEN + PEMBRO than with SUN (median not reached vs 28.7 mos; HR, 0.50; 95% CI 0.39–0.65; nominal P

TPS747 Background: The combination of immunotherapy with antiangiogenic agents is a well-established first-line treatment option for patients (pts) with advanced renal cell carcinoma (RCC), but many pts develop resistance, and effective second- or subsequent-line options are needed. The von Hippel-Lindau ( VHL) gene is inactivated in approximately 90% of RCC cases, which results in the constitutive activation of hypoxia-inducible factor 2α (HIF-2α) signaling. HIF-2α is involved in angiogenesis, tumor growth, proliferation, and metastasis, and is a key oncogenic driver in RCC. The HIF-2α inhibitor belzutifan has demonstrated promising antitumor activity with manageable safety in pts with heavily pretreated RCC. The cyclin-dependent kinase (CDK) pathway is altered in several cancer types, including RCC, and is associated with poor clinical outcomes. The CDK 4/6 inhibitor palbociclib inhibited cell growth in RCC cell lines, and the antiproliferative effects of CDK 4/6 inhibition were synergistic with HIF-2α inhibition in HIF-2α–dependent VHL -/- clear cell RCC cell lines. We hypothesized palbociclib could potentially enhance the efficacy of belzutifan as combination therapy for previously treated pts with advanced RCC. Methods: LITESPARK-024 (NCT05468697) is an open-label, multicenter, phase 1/2 randomized study of belzutifan + palbociclib versus belzutifan monotherapy in pts with advanced RCC. Pts must have histologically confirmed unresectable stage IV RCC with a clear cell component, received at least 2 prior systemic regimens (both an anti–PD-1/PD-L1 monoclonal antibody and a VEGF receptor–targeted TKI, in sequence or in combination), have measurable disease per RECIST v1.1 by BICR, have KPS score of ≥70%, and have radiographic disease progression on or after the most recent regimen per investigator. Part 1 will evaluate the safety of belzutifan + palbociclib and determine the recommended phase 2 dose (RP2D) for the combination using a modified toxicity probability interval design. Part 2 will evaluate the safety and efficacy of belzutifan + palbociclib versus belzutifan alone. In part 1, ≤30 pts will be enrolled into 3 dose groups and receive belzutifan 120 mg once daily + palbociclib (75, 100, or 125 mg) daily for 21 consecutive days followed by 7 days off. In part 2, approximately 150 pts will be randomly assigned 2:1 to receive belzutifan 120 mg once daily + palbociclib RP2D (21 consecutive days/7 days off) or belzutifan 120 mg once daily. Pts will be stratified by IMDC risk (0 vs 1-2 vs 3-6) and sarcomatoid histology (yes vs no) at randomization in part 2. The primary end point for part 1 is to assess dose-limiting toxicities and adverse events to determine the RP2D of belzutifan + palbociclib. The primary end point for part 2 is ORR per RECIST v1.1 by investigator assessment. Secondary end points for part 2 are clinical benefit rate, DOR, PFS, OS, and safety and tolerability. Clinical trial information: NCT05468697 .

BACKGROUND: Results from the phase 3 CLEAR study showed that lenvatinib plus pembrolizumab improved progression-free survival and overall survival compared with sunitinib in patients with advanced renal cell carcinoma. We aimed to assess the health-related quality-of-life (HRQOL) outcomes from the CLEAR study. METHODS: This open-label, randomised, phase 3 study was done across 200 hospitals and cancer centres in 20 countries. Patients were required to be 18 years or older, with advanced clear-cell renal cell carcinoma, and a Karnofsky performance status of 70% or higher. Patients who had received previous systemic anticancer therapy for renal cell carcinoma were not eligible. Patients were randomly assigned (1:1:1) to lenvatinib (oral 20 mg per day) plus pembrolizumab (intravenous 200 mg every 21 days), lenvatinib (oral 18 mg per day) plus everolimus (oral 5 mg per day) in 21-day cycles, or sunitinib (oral 50 mg per day, 4 weeks on followed by 2 weeks off). Patients were assigned to treatments with a computer-generated randomisation scheme and were stratified by geographical region and Memorial Sloan Kettering Cancer Center prognostic groups. The primary endpoint, previously reported, was progression-free survival, and HRQOL was a secondary endpoint. Most HRQOL analyses were done in patients who underwent randomisation, received at least one dose of study treatment, and had any HRQOL data. Completion and compliance analyses were done in the full analysis set. Functional Assessment of Cancer Therapy Kidney Symptom Index-Disease-Related Symptoms (FKSI-DRS), European Organisation for the Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 (EORTC QLQ-C30), and the EQ-5D-3 Level (EQ-5D-3L) preference questionnaire were administered at baseline and on day 1 of each subsequent 21-day cycle. This study is registered with ClinicalTrials.gov, NCT02811861, and is closed to new participants. FINDINGS: Between Oct 13, 2016, and July 24, 2019, 355 patients were randomly assigned to the lenvatinib plus pembrolizumab group, 357 to the lenvatinib plus everolimus group, and 357 to the sunitinib group. Median follow-up for HRQOL analyses was 12·9 months (IQR 5·6–22·3). Because of the promising efficacy and safety results of lenvatinib plus pembrolizumab in the first-line setting, we focus the HRQOL results in this report on that combination versus sunitinib. Mean change from baseline in the lenvatinib plus pembrolizumab group compared with the sunitinib group was −1·75 (SE 0·59) versus −2·19 (0·66) for FKSI-DRS, −5·93 (0·86) versus −6·73 (0·94) for EORTC QLQ-C30 global health status/quality of life (GHS/QOL), and −4·96 (0·85) versus −6·64 (0·94) for the EQ-5D visual analogue scale (VAS). Median time to first deterioration in the lenvatinib plus pembrolizumab group compared with the sunitinib group was 9·14 weeks (95% CI 6·43–12·14) versus 12·14 weeks (9·14–15·29; HR 1·13 [95% CI 0·94–1·35], log-rank p=0·20) for FKSI-DRS, 12·00 weeks (7·29–15·14) versus 9·14 weeks (6·29–12·14; 0·88 [0·74–1·05], log-rank p=0·17) for EORTC QLQ-C30 GHS/QOL, and 9·43 weeks (6·43–12·29) versus 9·14 weeks (6·29–12·00; 0·83 [0·70–0·99], log-rank p=0·041) for the EQ-5D VAS. Median time to definitive deterioration in the lenvatinib plus pembrolizumab group compared with the sunitinib group was 134·14 weeks (95% CI 120·00–not estimable) versus 117·43 weeks (90·14–131·29; HR 0·70 [95% CI 0·53–0·92], log-rank p=0·0081) for FKSI-DRS, 114·29 weeks (102·14–153·29) versus 75·14 weeks (57·29–105·14; 0·60 [0·47–0·77], log-rank p

Background Urothelial carcinoma (UC) is the most common subtype of bladder cancer. The randomized phase 3 KEYNOTE-045 trial showed that pembrolizumab, used as second-line therapy significantly prolonged overall survival with fewer treatment-related adverse events than chemotherapy for advanced UC. Pembrolizumab has been approved by the European Medicines Agency for the treatment of locally advanced or metastatic UC in adults who have received platinum-containing chemotherapy. Many European countries use cost-effectiveness analysis to inform reimbursement decisions. Objective To assess the cost-effectiveness of pembrolizumab as second-line therapy for the treatment of advanced UC from a Swedish health care perspective. Design, setting, and participants We developed a partitioned-survival model to assess the costs and effectiveness of pembrolizumab compared with vinflunine (base case), paclitaxel, or docetaxel monotherapy in patients with advanced UC over a 15-yr time horizon. We obtained Kaplan-Meier estimates for survival endpoints, adverse events, and utility data from KEYNOTE-045. Outcome measurements and statistical analysis We performed parametric extrapolations to estimate overall and progression-free survival beyond the clinical trial period. Swedish costs and utility weights were used to estimate total costs, quality-adjusted life years (QALYs), and incremental cost-effectiveness ratios (ICERs). We performed deterministic and probabilistic sensitivity analyses to assess the robustness of the model results. Results and limitations In the base-case analysis, pembrolizumab resulted in a mean survival gain of 1.66 years (1.38 QALYs) at an incremental cost of €69 852 and an ICER of €50 529/QALY gained versus vinflunine monotherapy. ICERs for other chemotherapies were €81 356/QALY for pembrolizumab versus paclitaxel or docetaxel monotherapy, and €71 924/QALY for pembrolizumab versus paclitaxel, docetaxel, or vinflunine monotherapy. Long-term follow-up from KEYNOTE-045 and real-world data are needed to validate the extrapolations. Conclusions The results indicate that pembrolizumab improves survival, increases QALYs, and is cost-effective as second-line therapy at a willingness-to-pay threshold of €100 000/QALY for the treatment of advanced UC. Patient summary To date, pembrolizumab is the only treatment associated with a significant overall survival benefit compared with chemotherapy in a randomized controlled trial as second-line therapy for advanced urothelial carcinoma. Our trial-based cost-effectiveness analysis suggests that pembrolizumab is a cost-effective option over chemotherapy in patients with advanced urothelial carcinoma after platinum-based therapy in Sweden.

The purpose of this systematic literature review (SLR) and meta-analysis was to compile the response of historic treatment options in first-line settings for patient populations who are cisplatin ineligible.SLR was conducted to compile objective response rate (ORR), duration of response (DOR), progression-free survival (PFS), and overall survival (OS) of historic therapies for this population based on stringent criteria. Clinical trials published in English from January 1991 to June 2016 were identified by searching the PubMed (Medline), Cochrane, and Embase databases.Eighteen studies (21 arms; N=810) were identified and used for this meta-analysis. For all treatments included in these studies, the pooled ORR was 0.36 (95% confidence interval [CI], 0.30-0.42). The ORR for the carboplatin+gemcitabine arms (6 arms; N=259), which is the National Comprehensive Cancer Network's recommended first-line treatment (before approval of atezolizumab and pembrolizumab) for this population was 0.36 (95% CI, 0.30-0.42), the median DOR (4 arms) was 7.00 months (95% CI, 4.34-11.29), and the median OS was 8.39 months (95% CI, 7.05-9.98).The results of this SLR clearly demonstrate the paucity of clinical studies that assess therapeutic intervention in truly cisplatin-ineligible advanced/metastatic urothelial carcinoma subjects and highlight the development of novel therapies that can create real improvement in long-term outcomes. The recent approval of 2 checkpoint inhibitors, atezolizumab and pembrolizumab, were added in the National Comprehensive Cancer Network guidance as recommended first-line treatment for cisplatin-ineligible patients with advanced/metastatic urothelial carcinoma and has provided alternatives for this patient population.

PURPOSE Programmed death 1 (PD-1) pathway inhibitors have not been prospectively evaluated in patients with non–clear cell renal cell carcinoma (nccRCC). The phase II KEYNOTE-427 study (cohort B) was conducted to assess the efficacy and safety of single-agent pembrolizumab, a PD-1 inhibitor, in advanced nccRCC. METHODS Patients with histologically confirmed, measurable (Response Evaluation Criteria in Solid Tumors [RECIST] version 1.1) nccRCC and no prior systemic therapy received pembrolizumab 200 mg intravenously once every 3 weeks for ≤ 24 months. The primary end point was objective response rate (ORR) per RECIST v1.1. RESULTS Among enrolled patients (N = 165), 71.5% had confirmed papillary, 12.7% had chromophobe, and 15.8% had unclassified RCC histology. Most patients (67.9%) had intermediate or poor International Metastatic RCC Database Consortium risk status and tumors with programmed death ligand 1 (PD-L1) combined positive score (CPS) ≥ 1 (61.8%). The median time from enrollment to database cutoff was 31.5 months (range, 22.7-38.8). In all patients, the ORR was 26.7%. The median duration of response was 29.0 months; 59.7% of responses lasted ≥ 12 months. The ORR by CPS ≥ 1 and CPS < 1 status was 35.3% and 12.1%, respectively. The ORR by histology was 28.8% for papillary, 9.5% for chromophobe, and 30.8% for unclassified. Overall, the median progression-free survival was 4.2 months (95% CI, 2.9 to 5.6); the 24-month rate was 18.6%. The median overall survival was 28.9 months (95% CI, 24.3 months to not reached); the 24-month rate was 58.4%. Overall, 69.7% of patients reported treatment-related adverse events, most commonly pruritus (20.0%) and hypothyroidism (14.5%). Two deaths were treatment related (pneumonitis and cardiac arrest). CONCLUSION First-line pembrolizumab monotherapy showed promising antitumor activity in nccRCC. The safety profile was similar to that observed in other tumor types.

PURPOSE Pembrolizumab, a programmed death 1 inhibitor, demonstrated promising single-agent activity in untreated patients with various cancer types. The phase II KEYNOTE-427 study evaluated efficacy and safety of single-agent pembrolizumab in treatment-naive patients with advanced clear cell renal cell carcinoma (ccRCC; cohort A) and advanced non-ccRCC (cohort B). Results of cohort A are reported. METHODS In this open-label, single-arm phase II study, patients with advanced ccRCC received pembrolizumab 200 mg every 3 weeks for ≤ 24 months. The primary end point was objective response rate by RECIST, version 1.1. RESULTS In the total population (N = 110), median time from enrollment to data cutoff was 35.9 (range, 29.5-40.3) months. Objective response rate was 36.4% with four (3.6%) complete responses and 36 (32.7%) partial responses; disease control rate was 58.2% (95% CI, 48.4 to 67.5). Most patients (68.2%) had a decrease in target lesions, including 30.9% with a reduction ≥ 60%. Median duration of response was 18.9 (range, 2.3-37.6+) months; 64.1% of responders had a response ≥ 12 months (Kaplan-Meier). Median progression-free survival was 7.1 months (95% CI, 5.6 to 11.0). Median overall survival was not reached; 12-month and 24-month overall survival rates were 88.2% and 70.8%, respectively. Durable responses were observed across all International Metastatic RCC Database Consortium categories. Grade 3-5 treatment-related adverse events were reported in 30.0% of patients, of which colitis and diarrhea were most frequent. CONCLUSION Single-agent pembrolizumab showed promising antitumor activity as a first-line treatment in patients with advanced ccRCC, with durable responses across International Metastatic RCC Database Consortium categories. Safety and tolerability profile of pembrolizumab monotherapy was comparable to what has been previously described in other tumor types.

269 Background: In pts with advanced RCC, second-line treatment with LEN + EVE prolonged progression-free survival (PFS) compared with EVE alone. LEN + PEMBRO, also showed preliminary efficacious evidence in a phase 1/2 RCC study. Here, we describe the investigational study results of first-line LEN + PEMBRO or LEN + EVE versus SUN in pts with advanced RCC. Methods: Pts were randomized (1:1:1) to receive LEN 20 mg orally once daily + PEMBRO 200 mg IV every 3 weeks (wks); or LEN 18 mg + EVE 5 mg orally once daily; or SUN 50 mg orally once daily (4 wks on/2 wks off). Eligible pts had advanced RCC with no prior systemic therapy. Randomization was stratified by geographic region and MSKCC prognostic group. The primary endpoint was PFS by Independent Review Committee per RECIST v1.1. Secondary endpoints included overall survival (OS), objective response rate (ORR) and safety. A sequential approach was used to test PFS first, then OS and ORR. PFS and OS were compared across arms by a stratified log-rank test; hazard ratios (HRs) were estimated by a stratified Cox regression model. Results: 1069 pts were randomized (Table). After a median follow-up of 27 months (data cutoff August 28, 2020), PFS was significantly improved with LEN + PEMBRO (median 24 months [mos]) vs SUN (median 9 mos; HR 0.39, 95% CI 0.32–0.49) and LEN + EVE (median 15 mos) vs SUN (HR 0.65, 95% CI 0.53–0.80). OS was significantly longer with LEN + PEMBRO vs SUN (HR 0.66, 95% CI 0.49–0.88), whereas OS with LEN + EVE vs SUN was not statistically different (HR 1.15, 95% CI 0.88–1.50). ORR was significantly greater with LEN + PEMBRO (ORR 71%; complete response [CR] 16%) vs SUN (ORR 36%; CR 4%; odds ratio 4.35, 95% CI 3.16–5.97) and LEN + EVE (ORR 54%; CR 10%) vs SUN (odds ratio 2.15, 95% CI 1.57–2.93). Grade ≥3 treatment-related adverse events occurred in 72% of pts in the LEN + PEMBRO arm and 73% of pts in the LEN + EVE arm compared with 59% of pts in the SUN arm. Conclusions: LEN + PEMBRO demonstrated significant improvements in PFS, OS and ORR vs SUN. LEN + EVE demonstrated significant improvements in PFS and ORR vs SUN. Safety was manageable and consistent with the known single-agent profiles. Clinical trial information: NCT02811861 . [Table: see text]

Objective: Pembrolizumab/axitinib significantly prolonged overall survival (OS) and progression-free survival (PFS) and increased objective response rate versus sunitinib in the phase III trial KEYNOTE-426 among previously untreated patients with advanced renal cell carcinoma (RCC). This study assessed the cost-effectiveness of pembrolizumab/axitinib versus other first-line treatments of advanced RCC from a US public healthcare payer perspective. Methods: A partitioned survival model with three states (progression-free, progressed, death) evaluated lifetime costs and quality-adjusted life-years (QALYs) for pembrolizumab/axitinib and other first-line regimens: sunitinib, pazopanib, and avelumab/axitinib in the overall population; and sunitinib, cabozantinib, and nivolumab/ipilimumab in the subgroup with intermediate/poor prognostic risk. Costs of treatments, adverse events, and medical resources were estimated. OS, PFS, and treatment duration were extrapolated using parametric models fitted to KEYNOTE-426 data and hazard ratios from network meta-analyses. Utilities were derived through mixed-effects regressions of KEYNOTE-426 EuroQol-5 Dimensions-3 Levels data. Results: In the overall population, pembrolizumab/axitinib was associated with incremental cost-effectiveness ratios (ICERs) of $95,725/QALY versus sunitinib and $128,210/QALY versus pazopanib, and was dominant (lower cost, higher effectiveness) versus avelumab/axitinib, with incremental QALY gains of 2.73, 2.40, and 1.80 versus these therapies, respectively. In the intermediate/poor-risk subgroup, base-case ICERs for pembrolizumab/axitinib were $101,030/QALY versus sunitinib, $6,989/QALY versus cabozantinib, and $130,934/QALY versus nivolumab/ipilimumab, with incremental QALY gains of 2.62, 1.78, and 1.06 versus these therapies. Conclusions: In this economic evaluation, pembrolizumab/axitinib was associated with higher life expectancy and QALYs and, based on typical willingness-to-pay thresholds of $150,000-$180,000/QALY, was found cost-effective versus other first-line treatments for advanced RCC in the US.

Purpose:Molecular profiling of large databases of human tumor gene expression profiles offers novel opportunities for informing decisions in clinical development programs.Experimental Design:Gene expression profile of programmed death ligand 1 (PD-L1) was explored in a dataset of 16,000 samples, including approximately 4,000 metastatic tumors, across >25 tumor types prevalent in the United States, looking for new indications for the programmed death 1 (PD-1) inhibitor pembrolizumab. PD-L1 expression was highly concordant with several genomic signatures indicative of immune-inflamed tumor microenvironment. Prevalence of activated immune-inflamed tumors across all tumor types was explored and used to rank tumor types for potential response to pembrolizumab monotherapy.Results:The analysis yielded 3 tiers of indications in which high levels of PD-L1 and immune-inflamed signatures were found in up to 40% to 60%, 20% to 40%, and 0% to 20% of tumors. Tier 1 contained novel indications known at the time of analysis to be responsive to PD-1 checkpoint blockade in the clinic (such as melanoma and non–small cell lung cancer), as well as indications not studied in the clinic previously, including microsatellite instability–high colorectal, head and neck, bladder, and triple-negative breast cancers. Complementary analysis of an Asian/Pacific cancer dataset (gastric cancer) revealed high prevalence of immune-inflamed tumors in gastric cancer. These data contributed to prioritization of these indications for clinical development of pembrolizumab as monotherapy.Conclusions:Data highlight the value of molecular profiling in identifying populations with high unmet needs with potentially favorable response characteristics and accelerating development of novel therapies for these patients.See related commentary by Mansfield and Jen, p. 1443

5069 Background: KEYNOTE-427 (NCT02853344), an open-label, single-arm, phase 2 study, showed clinical activity of first-line pembro monotherapy in patients (pts) with ccRCC (cohort A). Previous studies in RCC and immune-oncology suggest depth of response may correlate with long-term benefit. Association between depth of response and OS, along with updated efficacy and safety for cohort A of KEYNOTE-427, are presented. Methods: Pts with histologically confirmed ccRCC, measurable disease (RECIST v1.1), and no prior systemic therapy received pembro 200 mg IV Q3W for 2 y or until progressive disease, unacceptable toxicity, or withdrawal. End points: ORR (primary), DOR, and PFS (RECIST v1.1); OS, and safety. Association between depth of response (maximum reduction from baseline in the sum of target lesions) and OS was evaluated using Cox proportional hazards model with target lesion reduction group as time-varying covariate. Results: 110 pts enrolled; median time from enrollment to data cutoff was 23.1 (range, 16.7-27.5) mo. Overall, 38.2% of pts had favorable and 61.2% had intermediate/poor IMDC risk. ORR was 36.4% (95% CI, 27.4-46.1; 3 CRs, 37 PRs); median (range) DOR was not reached (2.3-23.5+ mo); 64.0% had a DOR ≥12 mo. Median PFS was 7.1 mo (95% CI, 5.6-11.0) and median OS was not reached; 18-mo PFS and OS rates were 26.6% and 80.0%, respectively. 69.1% had some reduction in target lesions. Pts with > 60% reduction in target lesions had a greater probability of survival than pts with a ≤60% reduction (Table). ORR observed in IMDC favorable and intermediate/poor risk was 31.0% and 39.7%, respectively; 18-mo OS rate was 95.2% for favorable and 70.5% for intermediate/poor IMDC risk. Treatment-related AEs (TRAEs) occurred in 81.8% of pts, primarily fatigue (29.1%) and pruritus (28.2%). Grade ≥3 TRAEs occurred in 29.1% of pts; 1 pt died of treatment-related pneumonitis. Conclusions: First-line pembro monotherapy was tolerable and showed promising antitumor activity in advanced ccRCC. In general, pts who had greater reductions in target lesions demonstrated a trend toward improved OS; pts with reduction of tumor burden ≥80% had comparable long term outcomes to those who achieved a RECIST 1.1 defined CR. Clinical trial information: NCT02853344 . [Table: see text]

4546 Background: VHL disease is associated with malignant or benign tumors, including renal cell carcinoma (RCC), pancreatic neuroendocrine tumors (pNETs), and hemangioblastomas. Alterations in the VHL gene cause aberrant stabilization and accumulation of HIF-2α, leading to activation of genes associated with tumor growth. Antitumor activity observed in the ongoing open-label phase 2 study, LITESPARK-004 (NCT03401788), led to the approval of belzutifan for the treatment of patients (pts) with VHL disease who require therapy for associated RCC, CNS hemangioblastomas, or pNETs not requiring immediate surgery. Updated results are presented after > 2 years of follow-up. Methods: Pts (≥18 years) with germline VHL alterations, ≥1 measurable nonmetastatic RCC tumor, no tumor of > 3 cm that necessitated immediate surgery, no prior anticancer systemic treatment, and an ECOG PS score of 0 or 1 received oral belzutifan 120 mg once daily until disease progression, unacceptable toxicity, or pt withdrawal. The primary end point was objective response rate (ORR) in VHL disease–associated RCC per RECIST v1.1 by independent central review (ICR). Secondary end points were safety, ORR in non-RCC neoplasms, and duration of response (DOR) in renal and nonrenal neoplasms, per RECIST v1.1 by ICR. Results: Of 61 pts, 50 were on treatment as of July 15, 2021; the primary reasons for discontinuation were disease progression in RCC neoplasms (n = 4) and pt decision to withdraw (n = 4). Twenty pts (33%) had ≥1 pNET and 50 (82%) had ≥1 CNS hemangioblastoma evaluable by ICR at baseline. At baseline, 97% of pts (n = 59) had prior VHL-related surgery; 38 pts had ≥1 VHL-related surgery within 3 years before starting belzutifan. Median time from first dose to database cutoff date was 29.3 mo (range, 27.6-37.5). ORR in RCC was 59% (n = 36), with 2 CRs (3%) and 34 PRs (56%). Median DOR was not reached (range, 8.3+ to 27.6+ mo). ORR in CNS hemangioblastomas was 38% (n = 19; 3 CRs; 16 PRs); median DOR was not reached (range, 3.7+ to 28.0+ mo). ORR in pNETS was 90% (n = 18; 3 CRs; 15 PRs); median DOR was not reached (range, 11.0+ to 31.0+ mo). Three pts (5%) underwent VHL-related surgeries after starting belzutifan. Grade 3 treatment-related adverse events (TRAEs) were reported in 10 pts (16%); the most common was anemia (n = 6 [10%]). No pt had a grade 4 or 5 TRAE. Two pts (3%) stopped treatment because of TRAEs (grade 1 dizziness and grade 2 intracranial hemorrhage). Conclusions: After a median follow-up of 29.3 mo, belzutifan continued to show antitumor activity in VHL disease–related neoplasms, including RCC, pNETs, and CNS hemangioblastomas, whereas the safety profile remained consistent with that of previous reports. These results support the use of belzutifan as a systemic treatment for VHL disease. Clinical trial information: NCT03401788.

4509 Background: Hypoxia-inducible factor 2α (HIF-2α) is a key oncogenic driver in RCC. Antitumor activity of the HIF-2α inhibitor belzutifan has been observed in RCC and is approved for treatment in patients (pts) with VHL disease who require therapy for associated RCC, CNS hemangioblastomas, or pNETs not requiring immediate surgery. Previous data from the phase 1 LITESPARK-001 trial (NCT02974738) designed to evaluate belzutifan in heavily pretreated RCC showed durable antitumor activity and an acceptable safety profile. After more than 3 years of follow-up for pts with ccRCC still receiving treatment, updated data are presented. Methods: Pts enrolled in the ccRCC cohort were previously treated with ≥1 therapy, had RECIST-measurable disease, ECOG PS score of 0 or 1, adequate organ function, and life expectancy of ≥6 months. Pts received oral belzutifan 120 mg once daily. The primary end point was safety. Secondary end points were ORR, DCR (CR + PR + SD), PFS, and DOR per RECIST v1.1 by investigator. The data cutoff date was July 15, 2021. Results: Of 55 pts enrolled in the ccRCC cohort, 9 (16%) remain on treatment as of the data cutoff date of July 15, 2021; the primary reason for discontinuation was progressive disease (n = 34; 62%). Pts received a median of 3 prior therapies (range, 1-9); 39 (71%) received prior VEGF and immunotherapy. Pts were followed while on treatment and for 30 days after the last dose for a median of 41.2 months (range, 38.2-47.7). Twenty-two pts (40%) experienced grade 3 TRAEs. The most common (≥10%) grade 3 TRAEs were anemia (n = 13; 24%) and hypoxia (n = 7; 13%). There were no grade 4 or 5 TRAEs. ORR was 25%, with 1 confirmed CR (2%) and 13 PRs (24%); DCR was 80%. Median DOR was not reached (range, 3.1+ to 37.9+ months); 8 of 14 responding pts (57%) remain in response as of the data cutoff date. Per IMDC risk, 4 of 13 pts with favorable risk achieved response (ORR = 31%; all PRs) and 10 of 42 pts with intermediate/poor risk achieved response (ORR = 24%; 1 CR, 9 PRs). DCR was 92% for pts with favorable risk and 76% for pts with intermediate/poor risk. For pts who received prior VEGF and immunotherapy, 8 of 39 pts achieved response (ORR = 21%; 1 CR; 7 PR); DCR was 74%. For the 16 pts who did not receive prior VEGF/immunotherapy, 6 achieved response (ORR = 38%; all PRs); DCR was 94%. Median PFS for the total cohort was 14.5 months (95% CI, 7.3-22.1); PFS rate at 156 weeks (̃36 months) was 34%. Conclusions: As seen after a median follow-up of > 3 years for pts still receiving treatment, belzutifan monotherapy continued to show a high rate of disease control and durable responses in previously treated pts with advanced ccRCC. Belzutifan exhibited a favorable safety profile, and no new safety signals were observed. In several phase 3 studies, belzutifan is being evaluated as monotherapy and combined therapy for ccRCC. Clinical trial information: NCT02974738.

Purpose: Pembrolizumab monotherapy, ipilimumab monotherapy, and pegylated interferon alfa-2b (PEG-IFN) monotherapy are active against melanoma and renal cell carcinoma (RCC). We explored the safety and preliminary antitumor activity of pembrolizumab combined with either ipilimumab or PEG-IFN in patients with advanced melanoma or RCC. Experimental Design: The phase Ib KEYNOTE-029 study (ClinicalTrials.gov, NCT02089685) included independent pembrolizumab plus reduced-dose ipilimumab and pembrolizumab plus PEG-IFN cohorts. Pembrolizumab 2 mg/kg every 3 weeks (Q3W) plus 4 doses of ipilimumab 1 mg/kg Q3W was tolerable if ≤6 of 18 patients experienced a dose-limiting toxicity (DLT). The target DLT rate for pembrolizumab 2 mg/kg Q3W plus PEG-IFN was 30%, with a maximum of 14 patients per dose level. Response was assessed per RECIST v1.1 by central review. Results: The ipilimumab cohort enrolled 22 patients, including 19 evaluable for DLTs. Six patients experienced ≥1 DLT. Grade 3 to 4 treatment-related adverse events occurred in 13 (59%) patients. Responses occurred in 5 of 12 (42%) patients with melanoma and 3 of 10 (30%) patients with RCC. In the PEG-IFN cohort, DLTs occurred in 2 of 14 (14%) patients treated at dose level 1 (PEG-IFN 1 μg/kg/week) and 2 of 3 (67%) patients treated at dose level 2 (PEG-IFN 2 μg/kg/week). Grade 3 to 4 treatment-related adverse events occurred in 10 of 17 (59%) patients. Responses occurred in 1 of 5 (20%) patients with melanoma and 2 of 12 (17%) patients with RCC. Conclusions: Pembrolizumab 2 mg/kg Q3W plus ipilimumab 1 mg/kg Q3W was tolerable and provided promising antitumor activity in patients with advanced melanoma or RCC. The maximum tolerated dose of pembrolizumab plus PEG-IFN had limited antitumor activity in this population. Clin Cancer Res; 24(8); 1805–15. ©2018 AACR.

375 Background: In the Study 111/KEYNOTE-146 trial (NCT02501096; N=147), lenvatinib (lenva) + pembrolizumab (pembro) showed encouraging antitumor activity and a manageable safety profile in treatment-naive (n=23) or previously treated metastatic RCC (n=105, previously treated with immune checkpoint inhibitor [ICI]; n=19, previously treated ICI naive); 145 had clear cell RCC and 2 had non-clear cell RCC. In this exploratory analysis, we evaluated the association between clinical outcomes and gene expression signatures and DNA variants for individual RCC-specific driver genes of interest based on published reports. Methods: Patients (pts) with metastatic RCC were treated with lenva 20 mg orally once daily + pembro 200 mg intravenously once every 3 weeks. The analysis population included pts with treatment-naive (n=10) and ICI pretreated (n=70) disease with evaluable RNA-sequencing data for the 18-gene T-cell–inflamed gene expression profile (TcellinfGEP) and for 11 other signatures (angiogenesis; glycolysis; gMDSC; hypoxia; mMDSC; MVD; MYC; proliferation; RAS; stroma/EMT/TGFβ; WNT) and whole exome sequencing (WES) data for DNA variants for individual genes ( VHL, PBRM1, BAP1, and SETD2). Specimens were collected prior to the start of treatment. The associations between each signature score and ORR and PFS per immune-related RECIST were evaluated using logistic regression and Cox proportional hazards, respectively. One-sided P values for TcellinfGEP (hypothesized positive association) and two-sided P values for all other signatures (no hypothesized association) were adjusted for multiplicity using the Hochberg step-up procedure; significance was prespecified at α=0.05. The association between DNA variants for individual genes and ORR was evaluated descriptively. Clinical data cutoff was August 18, 2020. Results: Of 147 treated pts, RNA sequencing and WES data were available for 80 (54%) and 60 (41%), respectively. TcellinfGEP was not associated with ORR ( P=0.827) or PFS ( P=0.741), nor were the other 11 signatures before or after adjustment for TcellinfGEP. ORR for DNA variants reported in the table. Conclusions: In this exploratory analysis of pts with metastatic RCC enrolled in Study 111/KEYNOTE-146 treated with lenva + pembro, responses were observed regardless of biomarker status. There were no statistically significant associations between gene signatures and clinical outcomes. Clinical benefit was observed regardless of VHL, PBRM1, BAP1, or SETD2 mutation status. Analyses in larger randomized datasets will provide additional information on the role of biomarkers in RCC. Clinical trial information: NCT02501096. [Table: see text]

331 Background: IO agents and TKIs have revolutionized treatment landscape of mRCC pts. Despite robust clinical trials’ data for these agents, real-world (rw) clinical outcomes data, especially from community setting in the US is limited. Methods: This retrospective cohort study included mRCC pts who received 1L treatment with either, pembrolizumab + axitinib (P+A) (IO+TKI), ipilimumab + nivolumab (I+P) (IO+IO) or cabozantinib, sunitinib, pazopanib and axitinib (TKI monotherapy (mono)) between 1/1/2018 and 9/30/2020 from The US Oncology Network of 480 sites. Patients were followed until 12/31/2020 to collect data on rw-time on treatment (rwToT), rw-time to next treatment (rwTTNT) and overall survival (OS). Kaplan-Meier analyses were performed to examine clinical outcomes. Results: We identified 1,538 eligible pts, of which 18% (n = 279) received P+A, 42% (n = 641) I+N and 40% (n = 618) TKI mono. The median follow-up duration for P+A, I+N and TKI mono cohort was 7.2 (range 0.0 - 20.5), 8.5 (range 0.0 - 32.3) and 7.8 (range 0.0 - 35.3) months, respectively. Majority of pts had clear cell histology (P+A - 82%, I+N - 86%, and TKI mono - 72%) and intermediate/poor IMDC risk score (P+A - 87%, I+N - 94%, and TKI mono - 81%). Median OS was not reached for P+A and was similar for I+N and TKI mono cohort (NR, 27.6, and 26.9 months, p=0.237, respectively). The median rwToT (13.6 vs. 5.8 vs. 3.4 months, p

338 Background: In the phase 3 CLEAR trial that included patients with aRCC, LEN + PEMBRO demonstrated significant improvements in progression-free survival (PFS; hazard ratio [HR] 0.39; 95% CI 0.32, 0.49; P < 0.001), overall survival (OS; HR 0.66; 95% CI 0.49, 0.88; P = 0.005) and objective response rate (ORR; odds ratio 4.35; 95% CI 3.16, 5.97) vs SUN. Here we report the efficacy and safety results of the East Asian population subset of the CLEAR trial. Methods: Patients with aRCC and no prior systemic therapy were randomized (1:1:1) to receive 1 of 3 treatments including LEN 20 mg PO QD + PEMBRO 200 mg IV Q3W and SUN 50 mg PO QD (4 weeks on/2 weeks off). Randomization was stratified by geographic region and MSKCC prognostic groups. This analysis compares the efficacy and safety of LEN + PEMBRO vs SUN in the East Asian subset of the CLEAR trial including patients from Japan and the Republic of Korea. The primary endpoint was PFS; secondary endpoints included OS, ORR and safety. An independent review committee assessed tumors per RECIST v1.1. Median PFS and OS were calculated using the Kaplan-Meier method; HR and 95% CI were estimated by a stratified Cox model. Odds ratios were estimated by a stratified Cochran-Mantel-Haenszel test. Results: Of the 1069 patients randomized, 75 patients in the LEN + PEMBRO group and 65 patients in the SUN group were from East Asia. PFS was improved with LEN + PEMBRO vs SUN (median 22.1 vs 11.1 mo; HR 0.38, 95% CI 0.23, 0.62). Median OS was not reached for both arms; the HR for OS comparing LEN + PEMBRO vs SUN was 0.71, 95% CI 0.30, 1.71. ORR was improved with LEN + PEMBRO vs SUN (65.3% vs 49.2%; odds ratio 2.14, 95% CI 1.07, 4.28). Grade ≥3 treatment emergent adverse events (TEAEs) occurred in 88.0% of patients in the LEN + PEMBRO group and in 79.7% of patients in the SUN group. The incidences and types of TEAEs were generally similar to the overall CLEAR population and were manageable with dose adjustments and appropriate concomitant therapies. Conclusions: Efficacy results for patients in the East Asian subset of the CLEAR trial were consistent with the results of the overall population. The safety profile of LEN + PEMBRO in the East Asian subset was also generally consistent with that of the overall population. Clinical trial information: NCT02811861. [Table: see text]

302 Background: Several immune-oncology (IO) agents and/or tyrosine kinase inhibitors (TKIs) have received approval for treatment of mRCC in 1L setting by Food and Drug Administration (FDA) over last few years. Limited data exists on evolving real-world treatment patterns and sequence in mRCC patients receiving these agents, especially at the community oncology setting. Methods: We used data from The US Oncology Network of over 1,300 providers from over 480 sites across United States from 01/01/2018 to 12/31/2020 (study period). Eligible study population included mRCC patients who received ipilimumab + nivolumab (Ipi+nivo) (IO+IO); pembrolizumab + axitinib (Pembro+axi) (IO+TKI); and axitinib (Axi) or cabozantinib (Cabo) or pazopanib (Pazo) or sunitinib (Suni) (TKIs monotherapy) in 1L setting until 09/30/2020. Descriptive statistics were used for cohort characterization. Results: We identified 3,756 mRCC patients, of which 1,538 were eligible including 42% (n=641) IO+IO, 18% (n=279) IO+TKI, and 40% (n=618) TKI monotherapy. The median age for the entire cohort was 67.1 years (range 25.0, 93.3), 70% (n=1,076) were male, 70% (n=1,081) were white, 38% (n=587) had BMI ≥ 30 and 79% (n=1,208) had clear cell histology. Among entire cohort, 87% (n=1,338) had intermediate/poor risk score as per International mRCC Database Consortium risk model. We noted a trend towards increased utilization of IO+IO and IO+TKI following their respective FDA approvals (IO+IO: April 2018, IO+TKI: April 2019) (Table). During the study period, overall, 35% (n=535), 12% (n=184), and 4% (n=62) mRCC patients received second-line (2L), third-line (3L) and fourth-line (4L) treatments, respectively. Cabo (49%) and pazo (12%); cabo (51%) and ipi+nivo (23%); and nivo (45%) and ipi+nivo (20%) were the most common 2L treatments in IO+IO, IO+TKI, and TKI monotherapy cohorts, respectively. Conclusions: This large real-world study examined use of new FDA approved mRCC treatments and their impact on treatment paradigm. The results show a rapid adaptation of these newer treatments in the community oncology settings. A longer follow-up is needed to assess their clinical impact and optimal treatment strategy in subsequent setting.[Table: see text]

TPS399 Background: Combination therapy with the PD-1 inhibitor pembrolizumab and the vascular endothelial growth factor (VEGF) inhibitor lenvatinib showed antitumor activity as first-line treatment for advanced clear cell RCC (ccRCC) in the phase 3 KEYNOTE-581/CLEAR study (NCT02811861). Antitumor activity has also been shown with the hypoxia-inducible factor 2α (HIF-2α) inhibitor belzutifan (MK-6482) in ccRCC and with MK-1308A (coformulation of pembrolizumab and the CTLA-4 inhibitor quavonlimab) in non–small cell lung cancer. Therefore, HIF-2α or CTLA-4 inhibition with a PD-1 and VEGF inhibition backbone combination may provide additional benefit as first-line treatment in ccRCC. This open-label, randomized, phase 3 study (NCT04736706) will compare first-line treatment with the novel combination therapies pembrolizumab + belzutifan + lenvatinib (arm A) or MK-1308A + lenvatinib (arm B) with pembrolizumab + lenvatinib (arm C) for advanced RCC. Methods: Approximately 1,431 adults with metastatic ccRCC, measurable disease per RECIST v1.1, and KPS score ≥70% who had not previously undergone systemic therapy for advanced ccRCC will be enrolled. Patients will be randomly assigned 1:1:1 to arm A (belzutifan 120 mg + lenvatinib 20 mg orally once daily [QD] + pembrolizumab 400 mg IV every 6 weeks [Q6W]), arm B (MK-1308A [quavonlimab 25 mg + pembrolizumab 400 mg] IV [Q6W] and lenvatinib 20 mg orally QD), or arm C (pembrolizumab 400 mg IV [Q6W] + lenvatinib 20 mg orally QD). Treatment will continue until documented disease progression, withdrawal of consent, or other discontinuation event; patients will receive pembrolizumab and MK-1308A for up to 18 cycles (̃2 years). Stratification factors are International mRCC Database Consortium (IMDC) score (favorable vs intermediate vs poor), region of the world (North America vs Western Europe vs rest of world), and sarcomatoid features (yes vs no). Response will be assessed by CT or MRI per RECIST v1.1 by blinded independent central review (BICR) at week 12 from randomization, Q6W through week 78, and every 12 weeks thereafter. Adverse events and serious adverse events will be monitored throughout the study and for 90 days after treatment. Dual primary end points are progression-free survival per RECIST v1.1 by BICR and overall survival for arm A or arm B versus arm C in patients with IMDC intermediate/poor status and in all patients regardless of IMDC status. Secondary end points are objective response rate and duration of response per RECIST v1.1 by BICR, patient-reported outcomes, and safety. The study is recruiting patients at sites across, Asia, Australia, Europe, North America, and South America. Clinical trial information: NCT04736706.

BackgroundPembrolizumab + vascular endothelial growth factor (VEGF) inhibitor lenvatinib demonstrated antitumor activity as first-line treatment for advanced clear cell renal cell carcinoma (ccRCC) in phase 3 trial KEYNOTE-581/CLEAR (NCT02811861). Hypoxia-inducible factor 2α (HIF-2α) inhibitor belzutifan (MK-6482) showed antitumor activity in ccRCC, and a coformulation of pembrolizumab and CTLA-4 inhibitor quavonlimab (MK-1308A) showed antitumor activity in non–small cell lung cancer. HIF-2α or CTLA-4 inhibition with PD-1 and VEGF inhibition backbone combination may provide additional benefit as first-line treatment in ccRCC. This open-label, randomized, phase 3 study (NCT04736706) will be conducted to compare novel combination therapies pembrolizumab + belzutifan + lenvatinib (arm A) and MK-1308A + lenvatinib (arm B) with pembrolizumab + lenvatinib (arm C).MethodsApproximately 1431 adults with metastatic ccRCC, measurable disease per RECIST v1.1, and Karnofsky Performance Status Scale score ≥70% who had not previously undergone systemic therapy for advanced ccRCC will be enrolled. Patients will be randomly assigned 1:1:1 to arm A (belzutifan 120 mg + lenvatinib 20 mg oral once daily + pembrolizumab 400 mg IV every 6 weeks), arm B (MK-1308A [quavonlimab 25 mg + pembrolizumab 400 mg] IV every 6 weeks and lenvatinib 20 mg oral once daily), or arm C (pembrolizumab 400 mg IV every 6 weeks + lenvatinib 20 mg oral once daily). Treatment will continue until documented disease progression, withdrawal of consent, or other discontinuation event; patients will receive pembrolizumab and MK-1308A for up to 18 cycles (approximately 2 years). Patients will be stratified by International mRCC Database Consortium (IMDC) score (favorable vs intermediate vs poor), region of the world (North America vs Western Europe vs rest of the world), and sarcomatoid features (yes vs no). Response will be assessed by CT or MRI per RECIST v1.1 by blinded independent central review (BICR) at week 12 from randomization, every 6 weeks through week 78, and every 12 weeks thereafter. Adverse events and serious adverse events will be monitored throughout the study and for 90 days after treatment. Dual primary end points are progression-free survival per RECIST v1.1 by BICR and overall survival. Primary end points will be assessed in arm A compared with arm C and in arm B compared with arm C for patients with IMDC intermediate/poor status and in all patients regardless of IMDC status. Secondary end points are objective response rate and duration of response per RECIST v1.1 by BICR, patient-reported outcomes, and safety.AcknowledgementsMedical writing and/or editorial assistance was provided by Matthew Grzywacz, PhD, of ApotheCom (Yardley, PA, USA). This assistance was funded by Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA, and Eisai Inc., Woodcliff Lake, NJ, USA. Funding for this research was provided by Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA,Eisai Inc., Woodcliff Lake, NJ, USA.Trial RegistrationClinicaltrials.gov, NCT04736706Ethics ApprovalThe study and the protocol were approved by the Institutional Review Board or ethics committee at each site.

BackgroundAccumulation and aberrant stabilization of transcription factor HIF-2α drives the expression of genes associated with progression of clear cell renal cell carcinoma (ccRCC). Belzutifan, a first-in-class HIF-2α inhibitor, has demonstrated promising antitumor activity with a favorable safety profile in patients with heavily pretreated ccRCC. The efficacy and safety of 2 doses of belzutifan in patients with advanced ccRCC who experienced progression after systemic therapy will be evaluated in this randomized, open-label, multicenter, phase 2 trial (NCT04489771).MethodsApproximately 150 adults will be randomly assigned 1:1 to receive oral belzutifan 120 mg once daily or 200 mg once daily. Patients with locally advanced or metastatic ccRCC (per RECIST v1.1) who experienced progression on or after 1 line of anti–PD-1/PD-L1 therapy as monotherapy or combined with other agents, with the immediately preceding line of treatment an anti–PD-1/PD-L1 therapy, will be enrolled. Progression is defined as received ≥2 doses of an anti–PD-1/PD-L1 agent and having demonstrated radiographic disease progression (per investigator). Other key eligibility criteria: ≤3 prior systemic regimens and a Karnofsky Performance Status Scale score ≥70%. Patients who previously received belzutifan or another HIF-2α inhibitor; require supplemental oxygen; have a baseline hemoglobin level AcknowledgementsMedical writing and/or editorial assistance was provided by Matthew Grzywacz, PhD of ApotheCom (Yardley, PA, USA). This assistance was funded by Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA. Funding for this research was provided by Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA.Trial RegistrationClinicaltrials.gov, NCT04489771Ethics ApprovalThe study and the protocol were approved by the Institutional Review Board or ethics committee at each site.

Summary Background More than half of all patients with advanced urothelial cancer cannot receive standard, first-line cisplatin-based chemotherapy because of renal dysfunction, poor performance status, or other comorbidities. We assessed the activity and safety of first-line pembrolizumab in cisplatin-ineligible patients with locally advanced and unresectable or metastatic urothelial cancer. Methods In this multicentre, single-arm, phase 2 study (KEYNOTE-052), cisplatin-ineligible patients with advanced urothelial cancer who had not been previously treated with systemic chemotherapy were recruited from 91 academic medical centres in 20 countries. Enrolled patients received intravenous pembrolizumab 200 mg every 3 weeks. The primary endpoint was objective response (the proportion of patients who achieved complete or partial response) in all patients and by PD-L1 expression status according to the Response Evaluation Criteria in Solid Tumors, version 1.1, as assessed by independent central review. PD-L1 expression was assessed in tumour and inflammatory cells from tumour biopsies provided at study entry. Activity and safety were analysed in all patients who received at least one dose of pembrolizumab (all-patients-treated population). This study is registered with ClinicalTrials.gov, number NCT02335424, and follow-up is ongoing. Findings Between Feb 24, 2015, and Aug 8, 2016, 374 patients were enrolled and 370 patients received at least one dose of pembrolizumab. 89 (24%, 95% CI 20–29) of 370 patients had a centrally assessed objective response, and as of Sept 1, 2016 (data cutoff), 74 (83%) of 89 responses were ongoing. Median follow-up was 5 months (IQR 3·0–8·6). A PD-L1-expression cutoff of 10% was associated with a higher frequency of response to pembrolizumab; 42 (38%, 95% CI 29–48) of 110 patients with a combined positive score of 10% or more had a centrally assessed objective response. The most common grade 3 or 4 treatment-related adverse events were fatigue (eight [2%] of 370 patients), alkaline phosphatase increase (five [1%]), colitis, and muscle weakness (both four [1%]). 36 (10%) of 370 patients had a serious treatment-related adverse event. 17 (5%) of 370 patients died from non-treatment-related adverse events associated with death, and one patient died from treatment-related adverse events (myositis in addition to grade 3 thyroiditis, grade 3 hepatitis, grade 3 pneumonia, and grade 4 myocarditis). Interpretation First-line pembrolizumab has antitumour activity and acceptable tolerability in cisplatin-ineligible patients with urothelial cancer, most of whom were elderly, had poor prognostic factors, or had serious comorbidities. In view of this result, pembrolizumab has become a new treatment option for patients who are cisplatin-ineligible or not suitable candidates for chemotherapy. Pembrolizumab in the first-line setting is being further assessed in the phase 3 KEYNOTE-361 trial (ClinicalTrials.gov, NCT02335424). Funding Merck & Co.

Background Novel second-line treatments are needed for patients with advanced urothelial cancer (UC). Interim analysis of the phase III KEYNOTE-045 study showed a superior overall survival (OS) benefit of pembrolizumab, a programmed death 1 inhibitor, versus chemotherapy in patients with advanced UC that progressed on platinum-based chemotherapy. Here we report the long-term safety and efficacy outcomes of KEYNOTE-045. Patients and methods Adult patients with histologically/cytologically confirmed UC whose disease progressed after first-line, platinum-containing chemotherapy were enrolled. Patients were randomly assigned 1 : 1 to receive pembrolizumab [200 mg every 3 weeks (Q3W)] or investigator's choice of paclitaxel (175 mg/m2 Q3W), docetaxel (75 mg/m2 Q3W), or vinflunine (320 mg/m2 Q3W). Primary end points were OS and progression-free survival (PFS) per Response Evaluation Criteria in Solid Tumors, version 1.1 (RECIST v1.1) by blinded independent central radiology review (BICR). A key secondary end point was objective response rate per RECIST v1.1 by BICR. Results A total of 542 patients were enrolled (pembrolizumab, n = 270; chemotherapy, n = 272). Median follow-up as of 26 October 2017 was 27.7 months. Median 1- and 2-year OS rates were higher with pembrolizumab (44.2% and 26.9%, respectively) than chemotherapy (29.8% and 14.3%, respectively). PFS rates did not differ between treatment arms; however, 1- and 2-year PFS rates were higher with pembrolizumab. The objective response rate was also higher with pembrolizumab (21.1% versus 11.0%). Median duration of response to pembrolizumab was not reached (range 1.6+ to 30.0+ months) versus chemotherapy (4.4 months; range 1.4+ to 29.9+ months). Pembrolizumab had lower rates of any grade (62.0% versus 90.6%) and grade ≥3 (16.5% versus 50.2%) treatment-related adverse events than chemotherapy. Conclusions Long-term results (>2 years' follow-up) were consistent with those of previously reported analyses, demonstrating continued clinical benefit of pembrolizumab over chemotherapy for efficacy and safety for treatment of locally advanced/metastatic, platinum-refractory UC. Trial registration ClinicalTrials.gov: NCT02256436.

Background: PD-1/L1-based combination regimens are the standard of care for first-line treatment of advanced clear cell RCC (ccRCC); however, there is no standard of care in the postimmunooncology/post-VEGF patient population, resulting in a high-unmet need. This umbrella platform study is an open-label, rolling-arm, multicenter phase 1b/2 trial in advanced ccRCC with an adaptive design that will evaluate safety and efficacy of experimental combinations of investigational agents targeting various mechanisms of action such as CTLA-4 (quavonlimab [MK-1308]), HIF-2α (belzutifan [MK-6482]), LAG-3 (MK-4280), ILT4 (MK-4830), PD-1 (pembrolizumab) and VEGF-TKI (lenvatinib). Substudy 03B (NCT04626518) will evaluate patients who progressed on PD-1/L1 inhibitors and VEGF-TKIs. Given the promising results of the phase 1b/2 KEYNOTE-146 study, pembrolizumab (400 mg IV Q6W) in combination with lenvatinib (20 mg orally QD) will be used as the reference arm. Methods: Patients will be aged ≥18 years with histologically confirmed diagnosis of ccRCC and KPS ≥70, and experience progression on or after having received treatment with a PD-1/L1 inhibitor and a VEGF-TKI (in sequence or in combination), as defined by RECIST v1.1). Progression on PD-1/L1 inhibitors is defined as receiving 2 doses of treatment, demonstrating radiographic disease progression per RECIST v1.1, and having documented disease progression within 12 weeks of last dose. The study will comprise a safety lead-in phase for experimental combinations with investigational agents without an established recommended phase 2 dose (RP2D) followed by an efficacy phase. Patients will be randomized 1:1 to an experimental arm (approximately 50 pts per arm) or the reference arm. If more than 1 experimental arm is open for enrollment, the pts in the reference arm can be shared. Experimental arms are pembrolizumab (400 mg Q6W IV) + belzutifan (MK-6482, 120 mg orally QD); lenvatinib (20 mg orally QD) + belzutifan (120 mg orally QD); MK-1308A (coformulation of quavonlimab 25 mg and pembrolizumab 400 mg IV Q6W); MK-4280A (coformulation of MK-4280 800 mg and pembrolizumab 200 mg IV Q3W); and pembrolizumab (200 mg IV Q3W) + MK-4830 (800 mg IV Q3W). Treatments will continue until disease progression, unacceptable toxicity, or withdrawal of consent. Stratification factors are IMDC risk group (favorable, intermediate, or poor) and use of a CTLA-4 inhibitor (yes vs no). Primary end points for safety lead-in phase (if applicable) are safety and tolerability to establish an RP2D; co-primary end points for efficacy phase are safety and objective response rate per RECIST v1.1 by blinded independent central review (BICR). Secondary end points during the efficacy phase are duration of response, progression-free survival, and clinical benefit rate per RECIST v1.1 (BICR), and overall survival. Citation Format: Hans Hammers, Toni Choueiri, Elizabeth Plimack, Brian Rini, Robert Motzer, Lina Yin, Rodolfo Perini, Jaqueline Willemann-Rogerio, Laurence Albiges. A phase 1b/2 umbrella study of investigational immune and targeted combination therapies for patients with advanced renal cell carcinoma (RCC) who progressed on PD-1/L1 and VEGF inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT243.

4555 Background: Inactivation of VHL leads to aberrant stabilization and accumulation of HIF-2α, which drives tumor growth. Patients (pts) with VHL disease are at risk for ccRCC, pancreatic neuroendocrine tumors (pNETs), and hemangioblastomas. Repeated surgeries are often needed to control ccRCC and other VHL disease manifestations. Prior results of this ongoing open-label phase 2 study (NCT03401788) showed activity with belzutifan in VHL disease. Updated results are presented. Methods: Adults with germline VHL alterations, measurable and localized/nonmetastatic ccRCC, no prior systemic anticancer therapy, and ECOG PS 0 or 1 received belzutifan 120 mg once daily until progression, intolerable toxicity, or decision to withdraw. The primary end point is ORR of VHL-associated ccRCC tumors per RECIST v1.1 by independent review committee (IRC). Secondary end points include DOR, time to response (TTR), PFS, and safety. Results: As of June 1, 2020, 61 pts enrolled. Most pts (82%) had ECOG PS 0, and the median number of prior tumor reduction procedures (eg, partial nephrectomy, craniotomy, radiation therapy) per pt was 5 (range, 0-15). Lesions outside the kidney (non-RCC tumors) evaluable by IRC included pNETs (33%) and CNS hemangioblastomas (82%). Median follow-up was 69 wk (range, 18-105), median duration of treatment was 68 wk (range, 8-105), and 56 pts (92%) remain on therapy. There were 22 confirmed responses (ORR, 36% [95% CI, 24-49]) and 7 (11%) unconfirmed responses (documented at 1 time point, to be confirmed at subsequent time point); all were PRs. In pts with confirmed PR, median DOR was not reached (range, 12+ to 62+ wk), median TTR was 31 wk (range, 12-61), and 56 pts (92%) had some reduction in the sum of all target lesion diameters. PFS rate at 52 wk was 98% (95% CI, 89-100). For non-RCC tumors, ORR was 80% (16/20; 1 CR) in pNETs and 32% (16/50; 1 CR) in CNS hemangioblastomas. Of 16 pts with evaluable retinal hemangioblastomas at baseline, 11 (69%) showed improvement per IRC. In those 16 pts, 29 eyes were monitored for retinal hemangioblastomas: 16 eyes (55%) showed improvement, 12 (41%) were stable, and no evaluation was available for 1 eye (3%). All 61 pts (100%) had at least one AE. The most common all-cause AE was anemia (90%), which is considered an on-target toxicity. Treatment-related AEs (TRAE) were reported by 60 pts (98%), and 8 pts (13%) had a grade 3 TRAE. No pts had grade 4/5 TRAEs. One pt discontinued treatment because of a TRAE (grade 1 dizziness). Conclusions: Belzutifan demonstrates clinical benefit and has a favorable safety profile in patients with VHL disease–associated ccRCC, pNETs, and hemangioblastomas. Clinical trial information: NCT03401788.

TPS4594 Background: For advanced clear cell RCC (ccRCC), first-line treatment with PD-1/PD-L1 inhibitors in combination with CTLA-4 inhibitors or VEGF TKIs are established treatment options. However, patients eventually experience progression; therefore, more effective therapies are needed. This umbrella platform study is an open-label, rolling-arm, multicenter, phase 1b/2 trial with an adaptive design that will evaluate the safety and efficacy of experimental combinations of investigational agents in advanced ccRCC based on their mechanisms of action and toxicity profile. Substudy 03A (NCT04626479) will evaluate treatment combinations as first-line therapy for patients with advanced ccRCC. Given promising results of the phase 1b/2 KEYNOTE-146 (NCT02501096) and phase 3 KEYNOTE-581/CLEAR (NCT02811861) studies, pembrolizumab (400 mg IV Q6W) + lenvatinib (20 mg orally QD) will be used as the reference arm. Methods: Patients must be aged ≥18 years with histologically confirmed ccRCC, measurable disease per RECIST v1.1, and KPS score ≥70 and must have not received prior systemic therapy for advanced RCC (neoadjuvant therapy is acceptable if completed ≥12 mo before randomization). The study will comprise a safety lead-in phase for experimental combinations with investigational agents without an established recommended phase 2 dose (RP2D) and an efficacy phase. Patients will be randomly assigned 2:1 to an experimental arm or a reference arm. Each experimental arm will contain approximately 80 patients. During the efficacy phase, if more than 1 experimental arm is open for enrollment, patients in the reference arm can be shared. Treatments in the experimental arms are composed of the following: MK-1308A (coformulation of quavonlimab [MK-1308] 25 mg + pembrolizumab 400 mg IV Q6W) + lenvatinib (20 mg orally QD), MK-4280A (coformulation of MK-4280 800 mg + pembrolizumab 200 mg IV Q3W) + lenvatinib (20 mg orally QD), and pembrolizumab (400 mg Q6W IV) + belzutifan (MK-6482, 120 mg orally QD) + lenvatinib (20 mg orally QD). Treatment with pembrolizumab (including coformulations with MK-1308 and MK-4280) will continue up to 2 years, whereas treatment with lenvatinib and belzutifan will continue until disease progression, unacceptable toxicity, or withdrawal of consent. Patients will be stratified by IMDC risk group (favorable vs intermediate/poor). Tumor imaging will occur 12 weeks after randomization, then Q6W until week 54, and Q12W thereafter. Coprimary end points are safety and tolerability, establishing the RP2D during the safety lead-in phase (if applicable) and objective response rate per RECIST v1.1 by blinded independent central review (BICR) during the efficacy phase. Secondary end points during the efficacy phase are duration of response, progression-free survival and clinical benefit rate per RECIST v1.1 (BICR), and overall survival. Clinical trial information: NCT04626479.

TPS4595 Background: Most RCCs contain clear cell histology; the remainder of cases are summarized as nccRCC. nccRCC is a heterogeneous group of tumors and, with advanced metastases, survival is uniformly worse than with clear cell RCC (ccRCC) because of the aggressiveness of these cancers and a lack of effective systemic treatment options. Because data are limited for patients with nccRCC, the role of various agents in the treatment of nccRCC is poorly defined and there is no standard of care; treatment guidelines recommend clinical trials as preferred strategy. Inhibition of the PD-1/PD-L1 pathway is an effective treatment option for nccRCC, and pembrolizumab monotherapy has shown efficacy with an acceptable safety profile as first-line treatment. The VEGF TKI lenvatinib has also shown efficacy with a tolerable safety profile as combination therapy with everolimus for nccRCC. Also, in the phase 3 KEYNOTE-581 study (NCT02811861), the combination of lenvatinib + pembrolizumab as first-line therapy showed antitumor activity in patients with metastatic ccRCC, suggesting this combination might be an excellent therapeutic option for nccRCC. The phase 2, open-label, single-arm, KEYNOTE-B61 study (NCT04704219) is being conducted to evaluate pembrolizumab in combination with lenvatinib as first-line treatment for nccRCC. Methods: Patients with centrally confirmed nccRCC, locally advanced/metastatic measurable disease per RECIST v1.1 per blinded independent central review (BICR), no prior systemic therapy for nccRCC, and KPS score ≥70 will be enrolled. Approximately 152 patients will receive pembrolizumab 400 mg every 6 weeks and lenvatinib 20 mg once daily. Pembrolizumab treatment will continue for up to approximately 2 years or until a discontinuation criterion is met (disease progression, unacceptable toxicity, or withdrawal of consent); lenvatinib treatment can continue beyond 2 years or until one of the same discontinuation criterion is met. Participants who discontinue one of the treatments can continue to receive the other treatment as monotherapy. A second-course treatment phase is available for patients who meet specific criteria. CT/MRI will be performed at 12 weeks from the start of treatment, every 6 weeks until week 54, and every 12 weeks thereafter. Adverse events will be monitored throughout the study and graded using CTCAE, version 5.0, guidelines. The primary end point is objective response rate based on RECIST v1.1 per BICR. Secondary efficacy end points for this study are clinical benefit rate, disease control rate, duration of response, progression-free survival, overall survival, and safety. Tertiary/exploratory end points are biomarker analysis and association with clinical response/disease etiopathogenesis. Clinical trial information: NCT04704219.

TPS372 Background: There is an unmet need for treatment options in the second-line or later setting following anti–PD-1/L1 or VEGF tyrosine kinase inhibitor (TKI) therapy in patients with advanced RCC. Hypoxia-inducible factor (HIF)-2α is a transcription factor that has been established as an oncogenic driver in clear cell RCC (ccRCC). Promising antitumor activity has been reported for the first-in-class small molecular HIF-2α inhibitor, MK-6482, in heavily pretreated patients with ccRCC and patients with VHL disease–associated RCC. HIF-2α also regulates VEGF gene expression and plays a role in resistance to anti-VEGF therapy. Therefore, combining MK-6842 with a VEGF receptor TKI, such as lenvatinib, is an attractive treatment option in the advanced RCC setting. Methods: This is a randomized, open-label, active-controlled, multicenter phase III trial evaluating the efficacy and safety of MK-6482 + lenvatinib compared with cabozantinib in patients with advanced ccRCC who have progressed on prior anti–PD-1/L1 therapy (NCT04586231). Eligibility criteria include age ≥18 years; histologically confirmed, unresectable, locally advanced or metastatic ccRCC; disease progression on or after first- or second-line systemic treatment with an anti–PD-1/L1 therapy (monotherapy or in combination with other agent[s]) for locally advanced or metastatic disease, the immediately preceding line of treatment must be an anti–PD-1/L1 therapy; no more than 2 prior systemic regimens, with only 1 prior anti–PD-1/L1 therapy; measurable disease per RECIST v1.1; and Karnofsky performance status ≥70%. Patients must provide tissue for biomarker analysis. Approximately 708 patients will be randomly assigned in a 1:1 ratio to receive MK-6482 120 mg orally once daily (QD) + lenvatinib 20 mg orally QD or cabozantinib 60 mg orally QD. Treatment will continue until disease progression, unacceptable toxicity, or withdrawal of consent. The stratification factors are International mRCC Database Consortium prognostic scores (0, 1-2, or 3-6), number of prior lines of therapy (1 or 2), and geographic region (North America, Western Europe, or rest of the world). Imaging will be assessed by CT or MRI every 8 weeks through week 80, then every 12 weeks thereafter. The dual primary end points are progression-free survival per RECIST v1.1 as assessed by blinded independent central review (BICR) and overall survival. Secondary end points are objective response rate and duration of response per RECIST v1.1 as assessed by BICR, and safety. Safety and tolerability will be evaluated using a tiered approach. Clinical trial information: NCT04586231 .

273 Background: Clear cell RCC (ccRCC) accounts for ~70% of kidney cancer cases in the US. Several first-line therapies are approved for ccRCC, but few patients respond completely and most progress within 5-11 mo. A key oncogenic driver in RCC is the transcription factor hypoxia-inducible factor 2α (HIF-2α). MK-6482 is a small molecule HIF-2α inhibitor that blocks the heterodimerization of HIF-2α with HIF-1β, inducing tumor regression in mouse xenograft RCC models. Updated data presented here include additional follow-up from the expansion cohort of patients with ccRCC from the first-in-human phase 1/2 study of MK-6482 in advanced solid tumors (NCT02974738). Methods: Patients were aged ≥18 y with advanced ccRCC, received ≥1 prior therapy, and had RECIST v1.1 measurable disease, ECOG status 0 or 1, adequate organ function, and life expectancy ≥6 mo. They received 120 mg of MK-6482 orally once daily. Tumors were assessed at baseline, within 7 days before week 9, and then every 8 weeks; response was assessed using RECIST v1.1. The primary end point was safety. Secondary end points included ORR, duration of response (DOR), and PFS. Results: Fifty-five patients with ccRCC were treated with MK-6482 120 mg (52 in expansion and 3 in dose-escalation cohorts). The median number of prior therapies was 3 (range 1-9). Forty-two patients (81%) previously received PD-1/L1 inhibitors and 48 (92%) previously received VEGF inhibitors. Thirteen patients (24%) were classified as favorable risk and 42 (76%) as intermediate or poor risk per IMDC criteria. With a median follow-up of 28 mo, the most common all-grade, all-cause AEs >30% were anemia (76%), fatigue (71%), dyspnea (49%), nausea (36%), cough (31%), and hypoxia (31%). Anemia (27%) and hypoxia (16%) were the most common grade 3 AEs. Two patients (4%) experienced grade 4 AEs, and 4 patients (7%) experienced grade 5 AEs. No grade 4 or 5 AEs were related to treatment. ORR was 25%, with 14 confirmed PRs. Thirty patients (55%) had SD, with a disease control rate (CR+PR+SD) of 80%. Median DOR was not reached; 77% had a response ≥6 mo. By IMDC risk, 4 of 13 patients with favorable risk had PR (ORR = 31%) and 10 of 42 with intermediate or poor risk had PR (ORR = 24%); disease control rate was 92% and 76%, respectively. Median PFS for the total population was 14.5 mo; 51% had a PFS of 12 mo. As of June 1, 2020, 33 patients (60%) discontinued because of PD and 2 (4%) because of AEs; 11 patients (20%) had ongoing treatment. Conclusions: MK-6482 remained well tolerated with a favorable safety profile and promising single-agent activity in patients with ccRCC for all IMDC risk groups after further follow-up. A phase III trial in a similar population is underway. Clinical trial information: NCT02974738 .

TPS368 Background: In ccRCC, HIF-2α is involved in the activation of genes such as VEGFA, cyclin D1, and CXCR4, which are associated with angiogenesis, tumor progression, and metastasis. HIF-2α can accumulate and be overactivated due to the inactivation of the Von Hippel-Lindau ( VHL) tumor suppressor gene, which occurs in most RCC cases. MK-6482 is a potent and selective small molecule inhibitor of HIF-2α that has shown antitumor activity in a phase I/II study in patients with pretreated, advanced ccRCC (NCT02974738). In the study, the objective response rate was 24%, the disease control rate was 80%, and the safety profile was acceptable. Methods: A phase III, open-label, multicenter, randomized, active-controlled study (NCT04195750) will evaluate the efficacy and safety of MK-6482 versus everolimus as second- to third-line therapy in advanced ccRCC. Eligibility criteria include age ≥18 years; unresectable, locally advanced, or metastatic ccRCC; measurable disease per RECIST v1.1; and a history 1 to 3 systemic regimens for locally advanced or metastatic RCC—including at least 2 doses of a PD-L1 inhibitor and a VEGF-targeted therapy alone or in combination, which resulted in progression. Exclusion criteria include diagnosis of hypoxia defined by pulse oximetry

272 Background: Belzutifan (MK-6482) inhibits HIF-2α and demonstrated antitumor activity and favorable safety as monotherapy in a phase 1 study of patients (pts) with metastatic ccRCC. Current study (NCT03634540) investigates belzutifan plus cabozantinib for pts with advanced ccRCC who were either treatment naive (cohort 1) or previously treated, including immunotherapy and TKIs (cohort 2). This preliminary analysis presents data from cohort 2. Methods: Pts had metastatic ccRCC and received no more than 2 prior systemic treatment regimens. Initially, 6 pts in either cohort 1 or 2 were treated with belzutifan 120 mg and cabozantinib 60 mg orally once daily for 21 days and a safety review committee performed an initial evaluation. For purpose of this preliminary analysis, efficacy was evaluated in pts who received ≥1 dose of treatment and had an opportunity of ≥6 mo of follow-up. Primary end point: objective response rate (ORR; RECIST v1.1 by investigator review). Secondary end points: progression free survival (PFS), overall survival (OS), and duration of response (DOR). Safety was evaluated for all cohort participants. Results: Evaluation of safety and tolerability of belzutifan 120 mg plus cabozantinib 60 mg was performed in the first 6 pts. Only 1 participant experienced a dose-limiting toxicity of hand-foot syndrome, therefore belzutifan 120 mg plus cabozantinib 60 mg was determined to be the recommended phase 2 dose. 53 pts were included in the safety analysis population. Median age was 64 yrs, 73.6% were male, 54.7% had ECOG PS 1. Twenty-eight (52.8%) received prior first-line and 24 (45.2%) prior second-line therapies. Median (range) time from enrollment to data cutoff was 11.3 mo (5.6-24.0) for pts with ≥6 mo of follow-up (n=41). The confirmed ORR was 22.0% (9 PRs) and 90.2% had any tumor shrinkage. Disease control rate (CR+PR+SD) was 92.7%. Median (range) DOR was not reached (3.7+ to 14.8+ mo); all responses were ongoing. Median (95% CI) PFS was 16.8 mo (9.2-not reached); PFS rate at 6 mo was 78.3%. OS rate at 6 mo was 95.0%. While 52 of 53 (98.1%) pts experienced a treatment-related adverse event (TRAE), 92% of events were grade 1 and 2. Most common (≥30%) TRAEs were anemia (75.5%), fatigue (67.9%), hand-foot syndrome (52.8%), diarrhea (45.3%), hypertension (43.4%), nausea (35.8%), and ALT/AST increase (32-34%). Incidence of grade 3 TRAEs >5% were hypertension (22.4%), anemia (11.3%), fatigue (11.3%), and ALT increase (5.7%). 2 pts experienced grade 3 hypoxia (3.8%). There were no grade 4 TRAEs or deaths. Discontinuations due to TRAEs occurred in 6 pts (11.3%) for belzutifan and 8 pts (15.1%) for cabozantinib. Conclusions: In this preliminary analysis, belzutifan in combination with cabozantinib demonstrated promising antitumor activity in previously treated pts with metastatic ccRCC. Safety was consistent with individual profiles of each agent. Clinical trial information: NCT03634540 .

333 Background: Patients (pts) with VHL disease are at risk of developing benign and malignant tumors, including ccRCC, pancreatic lesions tumors, CNS hemangioblastomas, and retinal lesions. Inactivation of VHL leads to stabilization of HIF-2α, which drives tumor growth. In a phase 1/2 study, MK-6482, a potent, selective, oral small molecule HIF-2α inhibitor, demonstrated favorable safety and antitumor activity in advanced ccRCC. We present results of the open-label phase 2 study of MK-6482 for VHL disease–associated ccRCC (NCT03401788). Methods: Adults with germline VHL alterations, measurable, localized/non-metastatic ccRCC, no prior systemic anticancer therapy, and ECOG PS 0/1 received MK-6482 120 mg once daily until progression, intolerable toxicity, or decision to withdraw. Primary end point: ORR of VHL-associated ccRCC tumors per RECIST v1.1 by independent review committee (IRC). Secondary end points: DOR, time to response (TTR), PFS, and safety. Results: As of June 1, 2020, 61 pts enrolled. The majority (82%) of pts had ECOG PS 0, and median number of prior surgeries per pt was 5 (range, 1-15). Lesions outside the kidney (non-RCC tumors) evaluable by IRC included pancreatic lesions (100%) and CNS hemangioblastomas (70%). Median duration of treatment was 68 wk (range, 8-105), and 92% of pts remain on therapy. There were 22 confirmed responses (ORR, 36% [95% CI, 24%-49%]) and 7 (11%) unconfirmed (documented at 1 time point, to be confirmed at subsequent time point) responses; all PRs. In pts with confirmed PR, median DOR was not reached (range, 12-62 wk) and median TTR was 31 wk (range, 12-61); 14 (64%) pts had response duration of ≥26 wk. 56 pts (92%) had any decrease in size of target lesions. PFS rate at 52 wk was 98% (95% CI, 89%-100%). Overall, pretreatment median linear growth rate of ccRCC tumors was +3.6 mm/y (range, −3.4 to +33.1), compared with −4.5 mm/y (range, −12.8 to +5.1) while on treatment. For non-RCC tumors, ORR in pancreatic lesions was 64% (39/61, including 4 CRs) and in CNS hemangioblastomas was 30% (13/43, including 5 CRs). Median (range) TTR was 35 wk (11-60) and 12 wk (10-60) for pancreatic lesions and CNS hemangioblastomas, respectively. 11/16 (69%) pts with evaluable retinal lesions at baseline showed improvement. Of those 16 pts, 29 eyes were followed for retinal lesions; 16 eyes (55%) showed improvement, 12 (41%) remained stable, and no follow-up evaluation was available for 1 (3%) eye. Treatment-related AEs (TRAEs) occurred in 98% of pts, none grade 4/5. Most common TRAE was anemia (87%), considered to be an on-target toxicity. One pt discontinued treatment due to a TRAE (grade 1 dizziness). As of data cutoff, 1 pt (2%) required surgery for ccRCC tumors after treatment. Conclusions: MK-6482 is an active and well-tolerated therapy for VHL disease–associated ccRCC, pancreatic lesions, as well as CNS and retinal hemangioblastomas. Clinical trial information: NCT03401788 .

327 Background: In the randomized, open-label, phase III KEYNOTE-426 study (NCT02853331), pembrolizumab + axitinib significantly improved overall survival (OS), progression-free survival (PFS), and objective response rate (ORR) versus sunitinib as first-line therapy for advanced RCC. Per protocol, patients could discontinue pembrolizumab or axitinib and continue the other agent. Pembrolizumab was stopped for all patients at 2 years. Axitinib could be continued until progression or toxicity. This exploratory subgroup analysis of KEYNOTE-426 describes outcomes of patients who completed 2 years of pembrolizumab. Methods: Patients included in KEYNOTE-426 were treatment naive, with clear cell RCC, KPS ≥70%, and measurable disease (RECIST v1.1). Patients were randomly assigned 1:1 to receive pembrolizumab 200 mg intravenously every 3 weeks for up to 35 doses + axitinib 5 mg orally twice daily or sunitinib 50 mg once daily (4 weeks on/2 weeks off) until progression, toxicity, or withdrawal. Primary end points of the original analysis were OS and PFS. Key secondary end points were ORR and safety. Results: Of 432 patients treated with pembrolizumab + axitinib, 129 (29.9%) completed 2 years of study therapy. Median (range) age of these patients was 61 (36-82) years, and 72.1% were male; 42 (32.6%) and 87 (67.4%) patients had International mRCC Database Consortium favorable and intermediate/poor risk, respectively, consistent with the intention-to-treat population (31.9% vs 68.1%). Median (range) follow-up (time from randomization to data cutoff) was 31.1 (24.0-37.7) months. For patients who completed 2 years of study therapy, the OS rates at 36 months was 93.8% (95% CI, 85.5%-97.4%). The PFS rates at 24 and 36 months were 72.7% (95% CI, 64.0%-79.7%) and 57.7% (95% CI, 46.3%-67.5%), respectively. The ORR was 85.3%, and the CR rate was 14.0%. 59.7% of patients experienced grade 3-5 treatment-related adverse events and 8.5% experienced grade 3-5 immune-mediated adverse events. Conclusions: In this exploratory analysis, a significant proportion of patients in the pembrolizumab + axitinib arm completed 2 years of pembrolizumab with ongoing clinical benefit. Clinical trial information: NCT02853331 .

TPS369 Background: Treatment options for RCC in the late-line setting after immunotherapy and vascular endothelial growth factor (VEGF)-targeted therapy are limited. Hypoxia-inducible factor (HIF)-2α is a transcription factor that has been established as an oncogenic driver in clear cell RCC (ccRCC). The first-in-class small molecular HIF-2α inhibitor, MK-6482, recently showed promising antitumor activity in a cohort of heavily pretreated ccRCC patients (pts) and in pts with von Hippel-Lindau–disease-associated RCC for which the FDA granted Breakthrough Therapy Designation to MK-6482. Methods: This randomized, open-label, multicenter phase II trial will evaluate the efficacy and safety of 2 doses of MK-6482 in pts with advanced RCC who have experienced progression after prior systemic therapy (NCT04489771). Eligible pts are male or female aged ≥18 years with histologically confirmed locally advanced or metastatic ccRCC (measurable disease per RECIST v1.1) who have experienced progression after 1-3 prior systemic therapies comprising an anti-PD-1/L1 agent combined with a VEGF-targeted tyrosine kinase inhibitor (TKI) or an anti-cytotoxic T lymphocyte-associated antigen-4 agent and have undergone no more than 3 prior systemic regimens; and a Karnofsky Performance Scale ≥70. Treatment progression on anti-PD-1/L1 combination therapy was defined as pts who received at least 2 doses of anti-PD-1/L1 therapy and demonstrated radiographic disease progression as assessed by the investigator. Pts who have received prior treatment with MK-6482 or another HIF-2α inhibitor, and those requiring intermittent or chronic supplemental oxygen, or with a baseline hemoglobin less than 10 g/dL, a history of human immunodeficiency virus, hepatitis B or hepatitis C infection, or active central nervous system metastases will be excluded. Approximately 150 pts will be randomly assigned 1:1 to oral MK-6482 120 mg once daily (QD) or 200 mg QD; treatment will continue until progression, unacceptable toxicity, or withdrawal. Pts will be stratified by International Metastatic RCC Database Consortium prognostic scores (0, 1-2, 3-6) and the number of prior TKI-containing therapies (0, 1, or 2-3). Imaging with computed tomography or magnetic resonance imaging will be undertaken on Week 9 from the date of randomization, every 8 weeks through Week 49, and every 12 weeks thereafter. Adverse events will be monitored throughout the study and for 30 days after treatment (90 days for serious adverse events). The primary end point is objective response rate per RECIST v1.1 by blinded independent central review (BICR). Secondary end points are progression-free survival, duration of response and clinical benefit rate per RECIST v1.1 by BICR, overall survival, pharmacokinetics, and safety. Safety will be analyzed using a tiered approach. This study is recruiting. Clinical trial information: NCT04489771 .

5003 Background: Patients (pts) with Von Hippel-Lindau disease (VHL) are at risk for several cancers, including clear cell renal cell carcinoma (ccRCC). Inactivation of VHL results in constitutive activation of the HIF-2α transcription factor, which drives tumor growth. MK-6482, a potent, selective, small molecule HIF-2α inhibitor, has shown favorable safety and antitumor activity in a phase 1/2 study. We present initial results of the open-label phase 2 study of MK-6482 for treatment of VHL-associated ccRCC (NCT03401788). Methods: Adult pts with a pathogenic germline VHL variation, measurable localized/nonmetastatic ccRCC, no prior systemic anticancer therapy, and ECOG PS of 0/1 received MK-6482 120 mg orally once daily until progression, intolerable toxicity, or investigator/pt decision to withdraw. Primary end point was ORR of VHL-associated ccRCC tumors per RECIST v1.1 by independent radiology review. Secondary end points were DOR, time to response (TTR), PFS, and safety and tolerability. Results: As of December 6, 2019, 61 pts were enrolled; median (range) age was 41 years (19-66) and most pts were male (52.5%) and had ECOG PS of 0 (82.0%). The most common lesions outside the kidney (non-RCC tumors) were CNS hemangioblastomas (80.3%) and pancreatic lesions (50.8%). Median (range) duration of treatment was 9.9 mo (1.9-18.2) and 95.1% of pts remain on therapy. Three pts discontinued (AE, n = 1; death [fentanyl toxicity], n = 1; pt decision, n = 1). There were 17 confirmed responses (ORR, 27.9% [95% CI, 17.1-40.8%]) and 8 (13.1%) unconfirmed (documented at 1 timepoint and to be confirmed at subsequent timepoint) responses; all responses were PRs. Of 61 pts, 53 (86.9%) had decrease in size of target lesions. In 17 pts with confirmed response, median (range) DOR was not reached (2.1-9.0 mo) and median (range) TTR was 5.5 mo (2.7-14.0). Responses were also observed in CNS, retinal, and pancreatic lesions. Median PFS was not reached; 12-mo PFS rate was 98.3%. Treatment-related AEs (TRAEs) occurred in 96.7% of pts, mostly grade 1 (44.3%) or grade 2 (42.6%) and primarily (≥20%) anemia (83.6%; considered an on-target-toxicity), fatigue (49.2%), and dizziness (21.3%). Grade 3 TRAEs occurred in 9.8% of pts, primarily fatigue (4.9%) and anemia (3.3%). There were no grade 4 or 5 TRAEs. One pt discontinued because of a TRAE (dizziness). Conclusions: MK-6482 showed promising efficacy and tolerability in pts with VHL-associated ccRCC and responses in other VHL-related lesions. These data support further investigation of MK-6482 in VHL disease. Clinical trial information: NCT03401788 .

5008 Background: LEN, a multikinase VEGFR inhibitor, plus everolimus is approved for advanced RCC after prior VEGF-targeted therapy. PEMBRO, an anti-PD-1 antibody, plus axitinib is approved as first-line therapy of advanced RCC. We report phase 2 results of the RCC cohort of a phase 1b/2 trial (Study 111/KEYNOTE-146) of LEN + PEMBRO in patients (pts) who progressed after ICI therapy. Methods: We performed a multicenter, open-label study of pts with mccRCC, who previously had disease progression by RECIST (confirmed ≥ 4 weeks later) during or following ICI therapy. Pts had measurable disease by immune-related RECIST, and ≥ 1 prior therapy. Pts received LEN 20 mg orally once daily plus PEMBRO 200 mg IV every 3 weeks until disease progression or toxicity. Tumor assessments were performed every 6 weeks (until week 24), then every 9 weeks. The primary endpoint was objective response rate (ORR) at Week 24 by irRECIST. Results: 104 pts were enrolled. At data cutoff (January 12, 2020), 71 (69%) pts were still on study treatment. Most pts had ≥2 prior anticancer regimens (58%). 91 of 104 pts were evaluable for response at Week 12 (13 pts NE at Week 12); 46 of 91 pts achieved a confirmed partial response for an ORR of 51% (Table). Median progression-free survival (PFS) was 11.7 months and median duration of response (DOR) was 9.9 months. The most common treatment-related adverse events (TRAEs) were fatigue (49%), diarrhea (44%), proteinuria (37%), hypertension (31%), nausea (31%), dysphonia (29%), stomatitis (29%), and arthralgia (27%). There was 1 grade 5 TRAE (upper gastrointestinal hemorrhage). 43% of pts required dose reduction and 12% of pts discontinued treatment due to TRAEs. Response and safety data will be updated to include all pts evaluable at an April 9, 2020 cut-off. Conclusions: LEN + PEMBRO demonstrated promising antitumor activity in pts with mccRCC with disease progression following ICI therapy. No new safety signals were detected. Efficacy outcomes by investigator review per irRECIST. Clinical trial information: NCT02501096 . [Table: see text]