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PURPOSE Effective treatments are needed for melanoma that progresses on inhibitors of programmed cell death protein-1 (PD-1) or its ligand (PD-L1). We conducted the phase II LEAP-004 study to evaluate the combination of the multikinase inhibitor lenvatinib and the PD-1 inhibitor pembrolizumab in this population (ClinicalTrials.gov identifier: NCT03776136 ). METHODS Eligible patients with unresectable stage III-IV melanoma with confirmed progressive disease (PD) within 12 weeks of the last dose of a PD-1/L1 inhibitor given alone or with other therapies, including cytotoxic T-cell lymphocyte–associated antigen 4 (CTLA-4) inhibitors, received lenvatinib 20 mg orally once daily plus ≤ 35 doses of pembrolizumab 200 mg intravenously once every 3 weeks until PD or unacceptable toxicity. The primary end point was objective response rate (ORR) per RECIST, version 1.1, by independent central review. RESULTS A total of 103 patients were enrolled and treated. The median study follow-up was 15.3 months. ORR in the total population was 21.4% (95% CI, 13.9 to 30.5), with three (2.9%) complete responses and 19 (18.4%) partial responses. The median duration of response was 8.3 months (range, 3.2-15.9+). ORR was 33.3% in the 30 patients with PD on prior anti–PD-1 plus anti–CTLA-4 therapy. The median progression-free survival and overall survival in the total population were 4.2 months (95% CI, 3.8 to 7.1) and 14.0 months (95% CI, 10.8 to not reached), respectively. Grade 3-5 treatment-related adverse events occurred in 47 (45.6%) patients, most commonly hypertension (21.4%); one patient died from a treatment-related event (decreased platelet count). CONCLUSION Lenvatinib plus pembrolizumab provides clinically meaningful, durable responses in patients with advanced melanoma with confirmed PD on prior PD-1/L1 inhibitor-based therapy, including those with PD on anti–PD-1 plus anti–CTLA-4 therapy. The safety profile was as expected. These data support lenvatinib plus pembrolizumab as a potential regimen for this population of high unmet need.

OBJECTIVES Parts 4 and 5 of the phase 1/2 KEYNOTE-022 study investigated the maximum tolerated dose (MTD), safety, and efficacy of pembrolizumab plus trametinib in solid tumours and BRAF wild-type melanoma. PATIENTS AND METHODS Patients received intermittent or concurrent dosing of pembrolizumab plus trametinib. Concurrent dosing was 2 or 4 weeks of trametinib run-in followed by concurrent pembrolizumab every 3 weeks (Q3W) plus trametinib once daily (QD). Intermittent dosing was 2 weeks of trametinib run-in followed by pembrolizumab plus intermittent trametinib (1 week off/2 weeks on). A 3 + 3 dose escalation was used, followed by dose confirmation. RESULTS Forty-two patients were enrolled. No dose-limiting toxicities (DLTs) occurred at initial dose levels (DL). At subsequent DLs, 10 of 38 evaluable patients had DLTs. For concurrent dosing, MTD was pembrolizumab 200 mg Q3W plus trametinib 1.5 mg QD, with a 2-week trametinib 1.5 mg QD run-in (concurrent DL2a); in concurrent DL2a group, five (31%) patients had grade 3/4 treatment-related adverse events (TRAEs); the objective response rate (ORR) was 0%. ORR was 40% in concurrent DL1 and 0% in concurrent DL2b. For intermittent dosing, MTD was pembrolizumab 200 mg Q3W plus trametinib 2 mg QD with a 2-week trametinib 2 mg QD run-in (intermittent DL2); in the intermittent DL2 group, seven (47%) patients had grade 3/4 TRAEs; ORR was 27%. ORR in intermittent DL1 was 33%. CONCLUSIONS MTDs for concurrent and intermittent dosing of pembrolizumab with trametinib were identified. The combination had limited antitumour activity, numerically higher ORR with intermittent versus concurrent dosing, and manageable safety. CLINICALTRIALS. GOV IDENTIFIER NCT02130466.

PURPOSE The combination of talimogene laherparepvec (T-VEC) and pembrolizumab previously demonstrated an acceptable safety profile and an encouraging complete response rate (CRR) in patients with advanced melanoma in a phase Ib study. We report the efficacy and safety from a phase III, randomized, double-blind, multicenter, international study of T-VEC plus pembrolizumab (T-VEC-pembrolizumab) versus placebo plus pembrolizumab (placebo-pembrolizumab) in patients with advanced melanoma. METHODS Patients with stage IIIB-IVM1c unresectable melanoma, naïve to antiprogrammed cell death protein-1, were randomly assigned 1:1 to T-VEC-pembrolizumab or placebo-pembrolizumab. T-VEC was administered at ≤ 4 × 106 plaque-forming unit (PFU) followed by ≤ 4 × 108 PFU 3 weeks later and once every 2 weeks until dose 5 and once every 3 weeks thereafter. Pembrolizumab was administered intravenously 200 mg once every 3 weeks. The dual primary end points were progression-free survival (PFS) per modified RECIST 1.1 by blinded independent central review and overall survival (OS). Secondary end points included objective response rate per mRECIST, CRR, and safety. Here, we report the primary analysis for PFS, the second preplanned interim analysis for OS, and the final analysis. RESULTS Overall, 692 patients were randomly assigned (346 T-VEC-pembrolizumab and 346 placebo-pembrolizumab). T-VEC-pembrolizumab did not significantly improve PFS (hazard ratio, 0.86; 95% CI, 0.71 to 1.04; P = .13) or OS (hazard ratio, 0.96; 95% CI, 0.76 to 1.22; P = .74) compared with placebo-pembrolizumab. The objective response rate was 48.6% for T-VEC-pembrolizumab (CRR 17.9%) and 41.3% for placebo-pembrolizumab (CRR 11.6%); the durable response rate was 42.2% and 34.1% for the arms, respectively. Grade ≥ 3 treatment-related adverse events occurred in 20.7% of patients in the T-VEC-pembrolizumab arm and in 19.5% of patients in the placebo-pembrolizumab arm. CONCLUSION T-VEC-pembrolizumab did not significantly improve PFS or OS compared with placebo-pembrolizumab. Safety results of the T-VEC-pembrolizumab combination were consistent with the safety profiles of each agent alone.

Melanoma can frequently metastasize to the brain with severe consequences. However, variation of melanoma brain metastases (MBM) development among populations is not well studied, and underlying mechanisms and risk factors for MBM development are not consistently documented. We conducted a systematic literature review (SLR) including a total of 39 articles to evaluate the proportion of melanoma patients who are diagnosed with, or develop, brain metastases, and summarize the risk factors of MBM. The average proportion of MBM was calculated and weighted by the sample size of each study. Meta-analyses were conducted for the selected risk factors using a random-effects model. The proportion of MBM at diagnosis was 33% (975 with MBM out of 2948 patients) among patients with cutaneous melanoma (excluding acral) and 23% (651/2875) among patients with cutaneous mixed with other types of melanoma. The proportion at diagnosis was lower among populations with mucosal (9/96, 9%) or uveal (4/184, 2%) melanoma and among populations outside the United States and Europe. Meta-analysis demonstrated that male vs. female gender and left-sided tumors vs. right-sided were significantly associated with increased risk of melanoma brain metastases. These data may help clinicians to assess an individual patient’s risk of developing melanoma brain metastases.

Background Pembrolizumab (PEMBRO) and ipilimumab + nivolumab (IPI + NIVO) are approved advanced melanoma (AM) immunotherapies. To address limited health-related quality of life (QoL) real-world evidence with immunotherapies in AM, we compared QoL in AM patients receiving either treatment in clinical practice. Methods A prospective US observational study enrolled adult AM patients initiating first-line PEMBRO or IPI + NIVO between June 2017 and March 2018. Endpoints included the QLQ-C30 global health score (GHS) and EuroQol visual analog scale (EQ-VAS) scores. Mean changes were compared using repeated measures mixed-effects models and are presented covariate adjusted. Results 225 PEMBRO and 187 IPI + NIVO patients were enrolled. From baseline through week 24, PEMBRO was associated with 3.2 mean GHS score increase (95% CI 0.5, 5.9; p = .02), while no change was observed with IPI + NIVO; 0.2 (95% CI − 2.6, 3.0; p = 0.87). Among objective treatment-responders, GHS scores associated with PEMBRO increased 6.0 (95% CI 3.1, 8.8; p p = .01). In treatment non-responders, IPI + NIVO was associated with GHS/QoL deterioration of − 3.7 (95% CI − 6.8, − 0.6; p = .02), PEMBRO non-responders demonstrated no change; 0.7 (95% CI − 2.3, 3.7; p = 0.6). Between treatments, PEMBRO patients increased 2.6 greater in EQ-VAS (95% CI 0.6, 4.5; p = .01) vs IPI + NIVO at 24 weeks. Conclusions PEMBRO was associated with better 24-week QoL compared to IPI + NIVO in actual clinical practice settings. Real-world data has known limitations, but with further confirmation these results may have implications for treatment selection.

BACKGROUND: Pembrolizumab shows robust antitumor activity and favorable safety in metastatic melanoma. KEYNOTE-151 evaluated pembrolizumab in Chinese patients, who have more aggressive melanoma subtypes than other populations. METHODS: Chinese patients aged ≥18 years with advanced melanoma previously treated with one line of therapy received pembrolizumab 2 mg/kg every 3 weeks for 35 cycles or until confirmed disease progression, intolerable toxicity, or study withdrawal. Primary end points were objective response rate (ORR) per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 by blinded independent central review and safety. Key secondary end points included duration of response (DOR) and progression-free survival (PFS) per RECIST v1.1 and overall survival (OS). RESULTS: Median age was 52 years (N = 103); 37.9% had acral and 14.6% had mucosal melanoma. Median follow-up was 7.9 months at data cutoff (December 27, 2017). ORR was 16.7% [95% confidence internal (CI), 10.0%-25.3%] (1 complete, 16 partial responses). Disease control rate was 38.2%. ORR was 15.8% for acral and 13.3% for mucosal melanoma. Median DOR was 8.4 months; 65.6% of patients had response duration ≥6 months. Median PFS was 2.8 months (95% CI, 2.7-3.5 months); 6-month rate was 20.4%. Median OS was 12.1 months (95% CI, 9.6 months–not reached); 6-month rate, 75.7%; and 12-month rate, 50.6%. Treatment-related AEs (TRAEs) occurred in 87 (84.5%) patients; 9 (8.7%) experienced grade 3/4 TRAE and 2 (1.9%) discontinued because of TRAE; none died. Two deaths occurred that were unrelated to treatment. CONCLUSIONS: Pembrolizumab was well tolerated and provided clinically meaningful antitumor activity as second-line therapy in Chinese patients with advanced melanoma.

TPS9589 Background: The treatment of melanoma has improved markedly with the emergence of new immune therapies, and both anti-PD-1 monotherapy and the combination of the anti-PD-1 antibody nivolumab and anti-CTLA-4 therapy ipilimumab are now considered standard-of-care in the unresectable or metastatic (advanced) melanoma setting. However, many patients have primary or acquired resistance to these therapies, thereby underpinning the need for more effective approaches. IO102-IO103 is a potentially first-in-class, dual-antigen, immune-modulatory therapy targeting the key cancer immune resistance pathways mediated by IDO and PD-L1. The ability of IO102 and IO103 to respectively activate the specific T cells that recognize these checkpoint molecules and directly modulate immune regulation has previously been demonstrated both preclinically and in human clinical trials. A synergistic anti-tumor response upon treatment against both IDO and PD-L1 has also previously been demonstrated in a preclinical model where IDO and PD-L1 were expressed by different cells in the tumor microenvironment. Due to the distinctive mechanisms of action of IO102-IO103 and anti-PD-1 antibodies, there may be a further synergistic effect when treatment is combined. A previous Phase 1/2 trial investigating the use of IO102-IO103 plus nivolumab in patients with anti-PD-1-naïve metastatic melanoma has demonstrated promising anti-tumor activity with an overall response rate (ORR) of 80%, median progression-free survival (PFS) of 26 months and a manageable safety profile (NCT03047928; Kjeldsen et al, Nat Med 2021). Methods: This is a Phase 3, multicenter, open-label, randomized, 2-arm trial investigating the efficacy and safety of IO102-IO103 plus pembrolizumab versus pembrolizumab alone (EudraCT: 2021-004594-32; ClinicalTrials.gov No: NCT05155254). Inclusion criteria include: adult patients with untreated, unresectable (Stage III), or metastatic (Stage IV) melanoma; > 6 months since last dose of (neo)adjuvant treatment with targeted or immune therapy (in those previously treated); and ≥1 measurable lesion by RECIST v1.1. Primary endpoint is PFS by blinded independent central review. Secondary endpoints include ORR, durable response rate, complete response rate, duration of response, time to response, disease control rate, overall survival, and safety/tolerability. Target enrollment is 300 patients at > 100 sites in 20 countries. Patients are randomized 1:1 to receive either pembrolizumab 200 mg intravenously (IV) every 3 weeks up to 2 years or pembrolizumab 200 mg IV every 3 weeks up to 2 years with dual-antigen IO103-IO102 85-85 µg and Montanide adjuvant subcutaneously on Day 1 and 8 of cycle 1 and 2 and on Day 1 of each cycle thereafter. Enrolment for the study is ongoing. Clinical trial information: EudraCT: 2021-004594-32; ClinicalTrials.gov No: NCT05155254.

Objective Patients with melanoma and early stable disease (SD) with pembrolizumab have unclear prognosis. We present post hoc analyses of long-term outcomes for patients with early SD, partial response (PR) or complete response (CR) with pembrolizumab. Patients and methods Patients who received pembrolizumab in the KEYNOTE-001 and KEYNOTE-006 studies and had SD, PR or CR at weeks 12 or 24 were included. Results Of 294 patients in the week 12 analysis, 107 (36.4%) had SD at week 12, of whom 7 (6.5%) had a best overall response of CR, 43 (40.2%) had PR and 57 (53.3%) had SD. Forty-eight–month overall survival (OS) rates were 95.2%, 73.0% and 47.7%, respectively, for patients with CR, PR and SD at week 12. Similar results were observed in the 241 patients in the week 24 analysis. Forty-eight–month OS rates were 72.1% for patients with SD at week 12 followed by subsequent response and 75.0% for patients with PR at week 12 followed by no change in response or progression. Thirty-six–month and 48-month OS rates were 11.6% and not reached, respectively, for patients with SD at week 12 followed by progression before week 24. Conclusions A substantial proportion of patients (46.7%) with early (week 12) SD with pembrolizumab achieved subsequent PR or CR. Patients with SD at week 12 and subsequent CR/PR had similar survival to those who maintained PR. In contrast, patients with SD at week 12 and subsequent progression had poor survival outcomes. These findings may guide treatment decisions for patients achieving early SD. Trial registration Clinicaltrials.gov : NCT01295827 (KEYNOTE-001); NCT01866319 (KEYNOTE-006).

ObjectiveLong-term safety of pembrolizumab in melanoma was analyzed in KEYNOTE-001, KEYNOTE-002, and KEYNOTE-006.Patients and methodsAnalysis involved patients who received ≥1 pembrolizumab dose. Lead-time bias was addressed via landmark analyses in patients who were progression-free before day 147.ResultsAdverse events (AEs) were analyzed for 1567 patients (median follow-up, 42.4 months). Most AEs were mild/moderate; grade 3/4 treatment-related AEs occurred in 17.7% of patients. Two pembrolizumab-related deaths occurred. Any-grade immune-mediated AEs (imAEs) occurred in 23.0%, most commonly hypothyroidism (9.1%), pneumonitis (3.3%), and hyperthyroidism (3.0%); grade 3/4 imAEs occurred in 6.9% of patients. Most imAEs occurred within 16 weeks of treatment. In landmark analysis, patients who did (n=79) versus did not (n=384) develop imAEs had similar objective response rates (ORRs) (64.6% versus 63.0%); median time to response (TTR), 5.6 months for both; median duration of response (DOR), 20.0 versus 25.3 months; median progression-free survival (PFS), 17.0 versus 17.7 months; median overall survival (OS), not reached (NR) versus 43 months (p=0.1104). Patients who did (n=17) versus did not (n=62) receive systemic corticosteroids had similar ORRs (70.6% vs. 62.9%) and median TTR (6.4 vs. 5.6 months) but numerically shorter median PFS (9.9 vs. 17.0 months); median DOR, 14.2 months versus NR; median OS, NR for both.ConclusionsThese results enhance the knowledge base for pembrolizumab in advanced melanoma, with no new toxicity signals after lengthy follow-up of a large population. In landmark analyses, pembrolizumab efficacy was similar regardless of imAEs or systemic corticosteroid use.Clinical trial registryNCT01295827, NCT01704287, NCT01866319.

Background Pembrolizumab is a standard of care for the treatment of unresectable or metastatic melanoma and an adjuvant treatment of melanoma with involvement of lymph node(s) following complete resection. However, new treatment options are needed to reduce the tumor burden before surgery and improve overall outcomes in patients with advanced melanoma. Methods MK-3475-U02 is a phase 1/2, rolling arm, multicenter, open-label, adaptive design study to evaluate the safety and efficacy of investigational agents with or without pembrolizumab or pembrolizumab alone for the treatment of melanoma. Patients will be enrolled in 1 of the 3 substudies. Substudy 02A will include patients with programmed death-1 (PD-1)–refractory melanoma (progressed after ≥2 doses of anti-PD-1/programmed death ligand-1 [PD-L1] therapy) randomized equally to treatment arms evaluating ≥1 investigational agent(s) with or without pembrolizumab. Enrollment is planned for up to ~100 patients per arm.Substudy 02B will include patients with unresectable stage III or stage IV melanoma not amenable to local therapy. Patients will be randomized 2:1 to combination (≥1 investigational agent(s) with or without pembrolizumab) or monotherapy (pembrolizumab alone) stratified by baseline lactate dehydrogenase status (normal/elevated) and prior adjuvant therapy with a PD-1 inhibitor (yes/no). Enrollment is planned for ~90 patients in the combination arm and ~45 in the control arm.Substudy 02C will include patients with stage IIIB/IIIC/IIID melanoma who are candidates for neoadjuvant therapy. Patients will be randomly assigned to combination (≥1 investigational agent(s) with or without pembrolizumab) or monotherapy (pembrolizumab alone). Surgical resection will be performed 6 weeks after the first dose of neoadjuvant study intervention. Enrollment is planned for ~25 patients in combination and ~15 in the pembrolizumab monotherapy arms.Treatment will continue for up to 2 years (up to 1 year neoadjuvant/adjuvant therapy for substudy 02C), until disease progression, unacceptable toxicity, or study discontinuation. The primary end points include safety (adverse events and study intervention discontinuations) for all 3 substudies; objective response rate by blinded independent central review per Response Evaluation Criteria in Solid Tumors 1.1 for substudies 02A and 02B, and pathological complete response (pCR) as assessed by central review of the pathology results for substudy 02C. Secondary end points include duration of response for substudies 02A and 02B, and recurrence-free survival, near pCR, and pathological partial response rates for substudy 02C. Results N/A Conclusions N/A Acknowledgements The authors thank the patients and their families for participating in these trials and all investigators and site personnel. Medical writing and/or editorial assistance was provided by Neha Tuli-Wildemore, MBBS, PhD, and Doyel Mitra, PhD, of the ApotheCom pembrolizumab team (Yardley, PA, USA). This assistance was funded by Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA. Trial Registration NCT04305041, NCT04305054, NCT04303169 Ethics Approval The study protocol and all amendments were approved by the relevant Institutional Review Board or ethics committee at each study site. All patients provided written informed consent to participate in the clinical trial. Consent N/A Reference N/A

Background Electroporated plasmid IL-12 (TAVO or tavokinogene telseplasmid) is a novel pro-inflammatory intratumoral therapy with substantial single agent activity in melanoma, which has been shown to synergize with anti-PD-1 antibodies in patients predicted as non-responders to anti-PD-1.1 2 Interim data from patients with stage III/IV melanoma actively progressing on anti-PD-1 antibody are presented herein. Methods Patients with confirmed disease progression by RECIST v1.1 after at least 12 weeks of treatment on pembrolizumab or nivolumab (or combination checkpoint blockade) and within 12 weeks of last dose (with no intervening therapies) were enrolled. There was no limit on the number of prior lines of therapy. At least one accessible lesion was electroporated with plasmid IL-12 (pIL-12-EP) on days 1, 5 and 8 every 6 weeks and pembrolizumab was administered every 3 weeks. Tumor response in treated and untreated lesions was assessed by RECIST v1.1 every 12 weeks. Endpoints include ORR, safety, PFS, OS, and DOR. Results The first 56 patients treated of 100 planned were included in this interim analysis. Of these, 84% had Stage IV disease, 30% had M1c or M1d disease, and 27% had prior exposure to ipilimumab. In 54 efficacy evaluable patients the investigator-assessed ORR was 30% (3 CR/13 PR), 5 patients had 100% reduction of target lesions. All responses have been confirmed, only two responding patient progressed while on study, 2 patients completed the study with ongoing responses (figures 1 and 2). In patients with M1c/M1d disease, the ORR was 35.2% (n=6/17). Tumor reduction was observed in untreated lesions in 12 of 12 patients who had unaccessible lesions or accessible untreated lesions. The median overall survival (mOS) and duration of response (mDOR) has not been reached, with a median follow-up time of 13 months. Grade 3 treatment-related adverse events (TRAEs) were seen in 5.4% of patients, and there were no grade 4/5 TRAEs. The rate of grade 3 treatment-emergent (TEAEs) regardless of cause was 23.2%. The median time for pIL-12-EP treatment was 10 minutes (range 2,46). Consistent with prior studies of single-agent pIL-12-EP, tumor IHC, and transcriptomic assessments revealed hallmarks of antigen-specific antitumor immunity in this study. Additional analyses including microbiome, TCR clonality, and peripheral blood biomarker assays will be presented. Conclusions In this rigorously defined PD-1 antibody refractory patient population, the addition of pIL-12-EP to PD-1 antibody therapy induced deep, durable, systemic response in local treated and distant visceral metastatic untreated lesions with nominal systemic toxicity. Trial Registration Trial Registration: NCT#03132675 Ethics Approval The study was approved by a central IRB and/or local institutional IRBs/Ethics Committees as required for each participating institution. Consent Written informed consent was obtained from the patients participating within the trial, the current abstract does not contain sensitive or identifiable information requiring an additional consent from patients. References Algazi A, Bhatia S, Agarwala S, et al. Intratumoral delivery of tavokinogene telseplasmid yields systemic immune responses in metastatic melanoma patients. Annals of Oncology 2019;31:532–540. Algazi A, Twitty C, Tsai K, et al. Phase II trial for IL-12 plasmid transfection and PD-1 blockade in immunologically quiescent melanoma. Clinical Cancer Research 2020;26:2827-2837.

Background Previous findings from the MASTERKEY-265 phase 1b study showed that the combination of T-VEC and pembrolizumab was well tolerated and produced a high complete response (CR) rate of 43% in patients with advanced melanoma.1 The 3-year progression-free survival (PFS) and overall survival (OS) rates at that time were 53.6% and 71%, respectively. Here, we report the results of the long-term follow-up efficacy analyses. Methods The MASTERKEY-265 phase 1b trial (NCT02263508) was an open-label, single-arm study that enrolled patients who had unresectable, stage IIIB-IVM1c melanoma with injectable, measurable lesions and no prior systemic treatment. T-VEC was administered intralesionally at the approved dosing starting day 1 of week 1. Pembrolizumab (200 mg) was administered intravenously Q2W beginning on day 1 of week 6. The maximum treatment period was 2 years. The primary endpoint was dose-limiting toxicities; key secondary endpoints included objective response rate and PFS per modified irRC, OS, and safety. Results As of the data cutoff (Mar 2, 2020), all 21 patients enrolled were off treatment; 6 died and 15 are in long-term follow-up. The median follow-up time was 58.6 months (range: 1.4–61.6). The CR rate remained 43% (9/21 patients). Twelve of the 13 responders (92.3%) are still in response, including all 9 patients with a CR. Median duration of response was not reached (range: 2.8+–54.3+ months). Median PFS and OS were not reached at the data cutoff. KM estimates of 4-year PFS and OS rates were 55.9% and 71.4%, respectively, which have held stable since the 3-year analysis. Patients who achieved a CR or partial response had better OS (p=0.0056) compared to those who did not respond. Median OS for non-responders was 24.4 months and was not reached for responders. No additional safety signals were detected. Conclusions At almost 5 years of follow-up, median PFS and OS were not reached for patients treated with the combination of T-VEC and pembrolizumab in this phase 1b study of unresectable metastatic melanoma. 92% of responders remained in response with improved OS observed in responders compared with non-responders. The corresponding randomized phase 3 trial has completed enrollment and is currently ongoing. Trial Registration NCT02263508 Ethics Approval The study was approved by the Ethics Board of each institution involved in this study and can be produced upon request. Reference Long G, Dummer R, Andtbacka R, et al. Follow-up analysis of MASTERKEY-265 Phase 1b (ph1b) trial of talimogene laherparepvec (T-VEC) in combination (combo) with pembrolizumab (pembro) in patients (pts) with unresectable stage IIIB–IVM1c melanoma (MEL). Pigment Cell Melanoma Res 2019;32:133–134.

Author(s): Ferrucci, Pier Francesco; Di Giacomo, Anna Maria; Del Vecchio, Michele; Atkinson, Victoria; Schmidt, Henrik; Schachter, Jacob; Queirolo, Paola; Long, Georgina V; Stephens, Rosalie; Svane, Inge Marie; Lotem, Michal; Abu-Amna, Mahmoud; Gasal, Eduard; Ghori, Razi; Diede, Scott J; Croydon, Elizabeth S; Ribas, Antoni; Ascierto, Paolo Antonio; KEYNOTE-022 international team | Abstract: BackgroundIn the KEYNOTE-022 study, pembrolizumab with dabrafenib and trametinib (triplet) improved progression-free survival (PFS) versus placebo with dabrafenib and trametinib (doublet) without reaching statistical significance. Mature results on PFS, duration of response (DOR), and overall survival (OS) are reported.MethodsThe double-blind, phase 2 part of KEYNOTE-022 enrolled patients with previously untreated BRAF V600E/K-mutated advanced melanoma from 22 sites in seven countries. Patients were randomly assigned 1:1 to intravenous pembrolizumab (200 mg every 3 weeks) or placebo plus dabrafenib (150 mg orally two times per day) and trametinib (2 mg orally one time a day). Primary endpoint was PFS. Secondary endpoints were objective response rate, DOR, and OS. Efficacy was assessed in the intention-to-treat population, and safety was assessed in all patients who received at least one dose of study drug. This analysis was not specified in the protocol.ResultsBetween November 30, 2015 and April 24, 2017, 120 patients were randomly assigned to triplet (n=60) or doublet (n=60) therapy. With 36.6 months of follow-up, median PFS was 16.9 months (95% CI 11.3 to 27.9) with triplet and 10.7 months (95% CI 7.2 to 16.8) with doublet (HR 0.53; 95% CI 0.34 to 0.83). With triplet and doublet, respectively, PFS at 24 months was 41.0% (95% CI 27.4% to 54.2%) and 16.3% (95% CI 8.1% to 27.1%); median DOR was 25.1 months (95% CI 14.1 to not reached) and 12.1 months (95% CI 6.0 to 15.7), respectively. Median OS was not reached with triplet and was 26.3 months with doublet (HR 0.64; 95% CI 0.38 to 1.06). With triplet and doublet, respectively, OS at 24 months was 63.0% (95% CI 49.4% to 73.9%) and 51.7% (95% CI 38.4% to 63.4%). Grade 3-5 treatment-related adverse events (TRAEs) occurred in 35 patients (58%, including one death) receiving triplet and 15 patients (25%) receiving doublet.ConclusionIn BRAF V600E/K-mutant advanced melanoma, pembrolizumab plus dabrafenib and trametinib substantially improved PFS, DOR, and OS with a higher incidence of TRAEs. Interpretation of these results is limited by the post hoc nature of the analysis.

10013 Background: 5-year follow-up of the phase 3 KEYNOTE-006 study (NCT01866319) showed pembro improved OS vs ipilimumab (ipi) in patients (pts) with advanced melanoma. 3-y OS rate from pembro completion for pts who completed 2 y of pembro was 93.8%. Results with 8 mo of additional follow-up are presented to inform clinical care. Methods: Eligible pts with ipi-naive advanced melanoma, ≤1 prior therapy for BRAF-mutant disease, and ECOG PS 0 or 1 were randomized to pembro 10 mg/kg Q2W or Q3W for ≤2 y or ipi 3 mg/kg Q3W for 4 doses. Pts discontinuing pembro with CR, PR, or SD after ≥94 weeks were considered pts with 2-y pembro. Pts who stopped pembro with SD, PR or CR could receive ≤12 mo of additional pembro (2nd course) upon disease progression if still eligible. ORR was assessed per immune-related response criteria by investigator review. OS was estimated using the Kaplan-Meier method. Pembro arm data were pooled. Post hoc ITT efficacy analyses are shown. Results: Median follow-up from randomization to data cutoff (Jul 31, 2019) was 66.7 mo in the pembro and 66.9 mo in the ipi arms. OS outcomes are shown in Table. For the 103 pts with 2-y pembro (30 CR, 63 PR, 10 SD), median follow-up from completion was 42.9 mo (95% CI, 39.9-46.3).Median DOR was not reached. 36-mo OS from pembro completion was 100% (95% CI, 100.0-100.0) for pts with CR, 94.8% (95% CI, 84.7-98.3) for pts with PR, and 66.7% (95% CI, 28.2-87.8) for pts with SD. 15 pts received 2nd-course pembro; BOR in 1st course was 6 CR, 6 PR, and 3 SD. Median time from end of 1st course to start of 2ndcourse was 24.5 mo (range, 4.9-41.4). Median follow-up in pts who received 2nd-course pembro was 25.3 mo (range, 3.5-39.4). Median duration of 2nd-course pembro was 8.3 mo (range, 1.4-12.6). BOR on 2ndcourse was 3 CR, 5 PR (ongoing responses, 7 pts), 3 SD (ongoing, 2 pts), and 2 PD (1 death); 2 pts pending. Conclusions: Pembro improves the long-term survival vs ipi in pts with advanced melanoma, with all pts who completed therapy in CR still alive at 5 years. Retreatment with pembro at progression in pts who stopped at SD or better can provide additional clinical benefit in a majority of pts. Clinical trial information: NCT01866319. [Table: see text]

Background Pembrolizumab+dabrafenib+trametinib demonstrated promising antitumor activity and acceptable tolerability in BRAF-mutant melanoma in phase 1/2 KEYNOTE-022 parts 1 and 2 (NCT02130466). Pembrolizumab+dabrafenib+trametinib numerically prolonged PFS and DOR versus placebo+dabrafenib+trametinib but had a higher grade 3-5 TRAE rate in part 3. KEYNOTE-022 parts 4 and 5 evaluated pembrolizumab+trametinib. Methods In part 4 (open-label, 3+3 dose-finding) patients with advanced solid tumors (irrespective of BRAF status) or unresectable/metastatic BRAF wild-type melanoma received pembrolizumab 200 mg Q3W with trametinib as concurrent (2 or 4 weeks of trametinib run-in [1.5 or 2 mg QD], then pembrolizumab+trametinib [1.5 or 2 mg QD]) or intermittent dosing (2 weeks of trametinib run-in [1.5 or 2 mg QD], then pembrolizumab+trametinib [1.5 or 2 mg QD; 1 week off/2 weeks on]). Interim MTDs identified in part 4 were confirmed in part 5 using a modified toxicity probability interval design. The primary objectives were safety, tolerability, and ORR by investigator assessment per RECIST v1.1 of the maximum administered or tolerated dose (MAD/MTD) of pembrolizumab+trametinib. Safety was analyzed for all patients who received ≥1 dose of study drug; patients treated during the trametinib run-in who discontinued study before receiving pembrolizumab were included; patients who did not complete trametinib run-in or receive ≥66% of planned doses during the 6-week dose-limiting toxicity (DLT) evaluable period were not included for DLT evaluation. AEs were graded per NCI CTCAE v4. Results Of 42 enrolled patients, most were female (61.9%); median age was 55.0 years; 57.1% had received ≥2 prior lines of therapy. At database cutoff (June 26, 2019), median follow-up was 9.0 months (range, 1.4-25.6 months). Of 38 DLT-evaluable patients, 10 had DLTs (table 1). Dosing regimens were selected for confirmation in part 5 based on safety data. Any-grade TRAEs occurred in 39 (92.9%) patients; grade 3-4 TRAEs occurred in 19 (45.2%), none were grade 5. TRAEs led to discontinuation in 8 (19.0%) patients. Immune-mediated AEs occurred in 12 (28.6%) patients, most commonly severe skin reactions (n=6; 14.3%), pneumonitis (n=3; 7.1%), hypothyroidism (n=2; 4.8%). The MTD of concurrent pembrolizumab+trametinib was pembrolizumab 200 mg Q3W plus trametinib 1.5 mg with 2 weeks of trametinib run-in (ORR, 0/16; 0%) and the MTD of intermittent pembrolizumab+trametinib was pembrolizumab 200 mg Q3W plus trametinib 2 mg with 2 weeks of run-in (ORR, 4/15; 26.7%). Conclusions Both concurrent or intermittent pembrolizumab+trametinib dosing were feasible and the combination showed antitumor activity in patients with advanced solid tumors or advanced BRAF wild-type melanoma.

The third multistakeholder Paediatric Strategy Forum organised by ACCELERATE and the European Medicines Agency focused on immune checkpoint inhibitors for use in combination therapy in children and adolescents. As immune checkpoint inhibitors, both as monotherapy and in combinations have shown impressive success in some adult malignancies and early phase trials in children of single agent checkpoint inhibitors have now been completed, it seemed an appropriate time to consider opportunities for paediatric studies of checkpoint inhibitors used in combination. Among paediatric patients, early clinical studies of checkpoint inhibitors used as monotherapy have demonstrated a high rate of activity, including complete responses, in Hodgkin lymphoma and hypermutant paediatric tumours. Activity has been very limited, however, in more common malignancies of childhood and adolescence. Furthermore, apart from tumour mutational burden, no other predictive biomarker for monotherapy activity in paediatric tumours has been identified. Based on these observations, there is collective agreement that there is no scientific rationale for children to be enrolled in new monotherapy trials of additional checkpoint inhibitors with the same mechanism of action of agents already studied (e.g. anti-PD1, anti-PDL1 anti-CTLA-4) unless additional scientific knowledge supporting a different approach becomes available. This shared perspective, based on scientific evidence and supported by paediatric oncology cooperative groups, should inform companies on whether a paediatric development plan is justified. This could then be proposed to regulators through the available regulatory tools. Generally, an academic-industry consensus on the scientific merits of a proposal before submission of a paediatric investigational plan would be of great benefit to determine which studies have the highest probability of generating new insights. There is already a rationale for the evaluation of combinations of checkpoint inhibitors with other agents in paediatric Hodgkin lymphoma and hypermutated tumours in view of the activity shown as single agents. In paediatric tumours where no single agent activity has been observed in multiple clinical trials of anti-PD1, anti-PDL1 and anti-CTLA-4 agents as monotherapy, combinations of checkpoint inhibitors with other treatment modalities should be explored when a scientific rationale indicates that they could be efficacious in paediatric cancers and not because these combinations are being evaluated in adults. Immunotherapy in the form of engineered proteins (e.g. monoclonal antibodies and T cell engaging agents) and cellular products (e.g. CAR T cells) has great therapeutic potential for benefit in paediatric cancer. The major challenge for developing checkpoint inhibitors for paediatric cancers is the lack of neoantigens (based on mutations) and corresponding antigen-specific T cells. Progress critically depends on understanding the immune macroenvironment and microenvironment and the ability of the adaptive immune system to recognise paediatric cancers in the absence of high neoantigen burden. Future clinical studies of checkpoint inhibitors in children need to build upon strong biological hypotheses that take into account the distinctive immunobiology of childhood cancers in comparison to that of checkpoint inhibitor responsive adult cancers. (C) 2020 The Authors. Published by Elsevier Ltd.

Purpose Pembrolizumab provides durable antitumor activity in metastatic melanoma, including complete response (CR) in about 15% of patients. Data are limited on potential predictors of CR and patient disposition after pembrolizumab discontinuation after CR. We describe baseline characteristics and long-term follow-up in patients who experienced CR with pembrolizumab in the KEYNOTE-001 study ( ClinicalTrials.gov identifier: NCT01295827). Patients and Methods Patients with ipilimumab-naive or -treated advanced/metastatic melanoma received one of three dose regimens of pembrolizumab. Eligible patients who received pembrolizumab for ≥ 6 months and at least two treatments beyond confirmed CR could discontinue therapy. Response was assessed every 12 weeks by central Response Evaluation Criteria in Solid Tumors version 1.1. For this analysis, CR was defined per investigator assessment, immune-related response criteria, and potential predictors of CR were evaluated using univariate and multivariate analyses. Results Of 655 treated patients, 105 (16.0%) achieved CR after median follow-up of 43 months. At data cutoff, 92 patients (87.6%) had CR, with median follow-up of 30 months from first CR. Fourteen (13.3%) patients continued to receive treatment for a median of ≥ 40 months. Pembrolizumab was discontinued by 91 patients (86.7%), including 67 (63.8%) who proceeded to observation without additional anticancer therapy. The 24-month disease-free survival rate from time of CR was 90.9% in all 105 patients with CR and 89.9% in the 67 patients who discontinued pembrolizumab after CR for observation. Tumor size and programmed death-ligand 1 status were among the baseline factors independently associated with CR by univariate analysis. Conclusion Patients with metastatic melanoma can have durable complete remission after discontinuation of pembrolizumab, and the low incidence of relapse after median follow-up of approximately 2 years from discontinuation provides hope for a cure for some patients. The mechanisms underlying durable CR require further investigation.

Summary Naturally stalled replication forks are considered to cause structurally abnormal chromosomes in tumor cells. However, underlying mechanisms remain speculative, as capturing naturally stalled forks has been a challenge. Here, we captured naturally stalled forks in tumor cells and delineated molecular processes underlying the structural evolution of circular mini-chromosomes (double-minute chromosomes; DMs). Replication forks stalled on the DM by the co-directional collision with the transcription machinery for long non-coding RNA. RPA, BRCA2, and DNA polymerase eta (Polη) were recruited to the stalled forks. The recruitment of Polη was critical for replication to continue, as Polη knockdown resulted in DM loss. Rescued stalled forks were error-prone and switched replication templates repeatedly to create complex fusions of multiple short genomic segments. In mice, such complex fusions circularized the genomic region surrounding MYC to create a DM during tumorigenesis. Our results define a molecular path that guides stalled replication forks to complex chromosomal rearrangements.

Background: Both pembrolizumab (PEMBRO) and ipilimumab + nivolumab (IPI + NIVO) are FDA-approved immunotherapy regimens for advanced melanoma (AM). Each regimen has different toxicity profiles pote...

BACKGROUND NF1-related PN can cause substantial morbidity, with no currently approved drug treatment available for PN treatment. Although surgery is the standard of care, complete resection of PN is often difficult due to encasement of vital structures and invasive and extensive PN growth. With limited real-world data among children with NF1-related PN, the study objectives were to describe the demographic, clinical characteristics, and treatment of these children. METHODS A cross-sectional analysis of existing CTF web-based, patient-entered, registry data collected between 2012–2018 was conducted. To be included in analysis, patients had to complete at least one registry survey, and be ≤ 19 years of age at the time of first survey completion, with patient- or parent/ guardian reported diagnosis of NF1 and at least 1 PN. Descriptive statistical analysis was conducted on data collected from the first survey for each patient, to describe patient characteristics and treatment patterns. Results were stratified by region (US, ex-US). RESULTS The sample included 943 pediatric patients (n=750 US, n=193 ex-US). The majority (85.9%) were less than 5 years of age at NF1 diagnosis (US: 87.6%; ex-US: 79.3%). Approximately half were male, and half reported more than 1 PN. The most common PN site include head (15.1%) and neck (12.6%). More than half of patients received no treatment (53.1%) for their PN. The most common treatments reported for PN were surgery (27.0%) and chemotherapy or drug therapy (10.0%). These results were generally consistent across regions. A malignant peripheral nerve sheath tumor (MPNST) and optic glioma (OG) were diagnosed in 21 (2.2%) and 308 (32.7%) patients, respectively; a large proportion of OG patients remained untreated (57.5%). Too few ex-US patients were available for detailed regional analysis. CONCLUSIONS This study demonstrated that a large proportion of children diagnosed with NF1-related PN remain untreated, highlighting a substantial unmet need.

Summary Background Immunotherapy combination treatments can improve patient outcomes. Epacadostat, an IDO1 selective inhibitor, and pembrolizumab, a PD-1 inhibitor, showed promising antitumour activity in the phase 1–2 ECHO-202/KEYNOTE-037 study in advanced melanoma. In this trial, we aimed to compare progression-free survival and overall survival in patients with unresectable stage III or IV melanoma receiving epacadostat plus pembrolizumab versus placebo plus pembrolizumab. Methods In this international, randomised, placebo-controlled, double-blind, parallel-group, phase 3 trial, eligible participants were aged 18 years or older, with unresectable stage III or IV melanoma previously untreated with PD-1 or PD-L1 checkpoint inhibitors, an ECOG performance status of 0 or 1, and had a known BRAFV600 mutant status or consented to BRAFV600 mutation testing during screening. Patients were stratified by PD-L1 expression and BRAFV600 mutation status and randomly assigned (1:1) through a central interactive voice and integrated web response system to receive epacadostat 100 mg orally twice daily plus pembrolizumab 200 mg intravenously every 3 weeks or placebo plus pembrolizumab for up to 2 years. We used block randomisation with a block size of four in each stratum. Primary endpoints were progression-free survival and overall survival in the intention-to-treat population. The safety analysis population included randomly assigned patients who received at least one dose of study treatment. The study was stopped after the second interim analysis; follow-up for safety is ongoing. This study is registered with ClinicalTrials.gov , number NCT02752074 . Findings Between June 21, 2016, and Aug 7, 2017, 928 patients were screened and 706 patients were randomly assigned to receive epacadostat plus pembrolizumab (n=354) or placebo plus pembrolizumab (n=352). Median follow-up was 12·4 months (IQR 10·3–14·5). No significant differences were found between the treatment groups for progression-free survival (median 4·7 months, 95% CI 2·9–6·8, for epacadostat plus pembrolizumab vs 4·9 months, 2·9–6·8, for placebo plus pembrolizumab; hazard ratio [HR] 1·00, 95% CI 0·83–1·21; one-sided p=0·52) or overall survival (median not reached in either group; epacadostat plus pembrolizumab vs placebo plus pembrolizumab: HR 1·13, 0·86–1·49; one-sided p=0·81). The most common grade 3 or worse treatment-related adverse event was lipase increase, which occurred in 14 (4%) of 353 patients receiving epacadostat plus pembrolizumab and 11 (3%) of 352 patients receiving placebo plus pembrolizumab. Treatment-related serious adverse events were reported in 37 (10%) of 353 patients receiving epacadostat plus pembrolizumab and 32 (9%) of 352 patients receiving placebo plus pembrolizumab. There were no treatment-related deaths in either treatment group. Interpretation Epacadostat 100 mg twice daily plus pembrolizumab did not improve progression-free survival or overall survival compared with placebo plus pembrolizumab in patients with unresectable or metastatic melanoma. The usefulness of IDO1 inhibition as a strategy to enhance anti-PD-1 therapy activity in cancer remains uncertain. Funding Incyte Corporation, in collaboration with Merck Sharp & Dohme.

Background: Immunotherapy combination treatments may improve patient outcomes. Epacadostat, an indoleamine 2,3-dioxygenase 1 (IDO1) selective inhibitor, and pembrolizumab, a programmed death protein (PD)-1 inhibitor, showed promising antitumour activity in the phase 1/2 ECHO-202/KEYNOTE-037 advanced melanoma study. Methods: In the phase 3 ECHO-301/KEYNOTE-252 (NCT02752074) study, patients with unresectable stage III or IV melanoma previously untreated with checkpoint inhibitors were stratified by PD-ligand-1 expression and BRAF mutation status, and randomised (1:1) to epacadostat 100 mg twice-daily (BID) plus pembrolizumab 200 mg every 3 weeks (Q3W) or placebo plus pembrolizumab 200 mg Q3W for up to 2 years. Primary endpoints were progression-free survival (PFS) per modified Response Evaluation Criteria In Solid Tumors (RECIST) v1.1 and overall survival (OS). Secondary endpoints included objective response rate (ORR) per modified RECIST v1.1, duration of response (DOR), and safety. We report PFS final and OS interim analyses. Findings: 706 patients were randomised (n=354 epacadostat plus pembrolizumab, n=352 placebo plus pembrolizumab). Median follow-up was 12·4 months. No significant difference was found between epacadostat plus pembrolizumab versus placebo plus pembrolizumab for PFS (median 4·7 vs 4·9 months, respectively; HR=1·00; CI, 0·83-1.21; one-sided p=0·517) or OS (HR=1·13; 95% CI 0·86 1·49; one-sided p=0·807). Twelve-month OS rate was 74% (both groups). ORR was 34·2% (epacadostat plus pembrolizumab) and 31·5% (placebo plus pembrolizumab). Median DOR was not reached (both groups). Grade ≥3 treatment-related adverse events were reported in 21·8% of patients receiving epacadostat plus pembrolizumab; 17·0% receiving placebo plus pembrolizumab. Interpretation: Epacadostat 100 mg BID plus pembrolizumab did not improve PFS or OS versus pembrolizumab alone in unresectable or metastatic melanoma patients. Utility of IDO1 inhibition as a strategy to enhance anti-PD-1 therapy activity in cancer remains uncertain. Funding: Incyte Corporation (Wilmington, DE, USA) in collaboration with Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA. Declaration of Interest: GVL has served as a consultant/advisor for Amgen, Array, Bristol-Myers Squibb, Incyte, Merck Sharp and Dhome, Novartis, Pierre Fabre, and Roche; has received honoraria from Bristol-Myers Squibb, Incyte, Merck Sharp and Dhome, Novartis, and Roche; and personal fees for travel to conferences from Merck Sharp and Dhome and Roche. RD has served as a consultant/advisor for Amgen, Bristol-Myers Squibb, Merck Sharp and Dhome, Novartis, Pierre Fabre, Roche, Sanofi, Sun Pharma, and Takeda. OH has served as a consultant/advisor for and/or received honoraria from Amgen, Bristol-Myers Squibb, Incyte, Merck, Novartis, and Roche; served on speakers bureau for Amgen, Array, Bristol-Myers Squibb, Genentech, Novartis, and Sanofi; and his institution has received research funding from AstraZeneca, Bristol-Myers Squibb, Celldex, Genentech, Immunocore, Incyte, Merck, Merck Serono, Medimmune, Novartis, Pfizer, and Rinat. TFG has served on advisory boards for Merck and his institution has received research grants from Merck and Incyte. CC has served as a consultant for AstraZeneca, Bayer, Bristol-Myers Squibb, and Merck Sharp and Dhome; served on speakers bureau for Bayer, Bristol-Myers Squibb, Eli Lilly, and Merck Sharp and Dhome; received personal fees and for travel and non-financial support from Boehringer Ingelheim and Bristol-Myers Squibb; and has received research grants from Astellas Pharma, AstraZeneca, Bayer, Boehringer Ingelheim, Bristol-Myers Squibb, Medivation, Merck Sharp and Dhome, and Roche. SD received personal fees from Sanofi; non-financial support for travel and research from Bristol-Myers Squibb and Merck Sharp and Dhome; and research grant from Bristol-Myers Squibb. AA has served as a consultant and on speakers bureau for Bristol-Myers Squibb, Merck Sharp and Dhome, Novartis, and Roche. MSC has served as a consultant for Amgen, Bristol-Myers Squibb, Merck Sharp and Dhome, Novartis, and Pierre Fabre. J-JG has served as a consultant/advisor for and/or received honoraria from Amgen, Bristol-Myers Squibb, Incyte, Merck/Pfizer, Merck Sharp and Dhome, Novartis, Pierre Fabre, Roche, Sanofi, and Sun Pharma; has served on speakers bureau for Novartis; and received other support for travel from Amgen, Bristol-Myers Squibb, Merck Sharp and Dhome, Pierre Fabre, and Roche. TMK declares no competing interests. LD has served as a consultant for and received honoraria and research grants from Bristol-Myers Squibb, Merck Sharp and Dhome, Novartis, and Roche. CR has served as a consultant/advisor for and received honoraria from Amgen, Bristol-Myers Squibb, Merck, Novartis, Pierre Fabre, and Roche. JL has served as a consultant for Achilles, AstraZeneca, Boston Biomedical, Bristol-Myers Squibb, Eisai, EUSA Pharma, GlaxoSmithKline, Ipsen, Imugene, Incyte, iOnctura, Kymab, Merck Serono, Merck Sharp and Dhome, Nektar Therapeutics, Novartis, Pierre Fabre, Pfizer, Roche/Genentech, Secarna, and Vitaccess; his institute has received grants from Achilles Therapeutics, Aveo, Bristol-Myers Squibb, Covance, Immunocore, Merck Sharp and Dhome, Nektar Therapeutics, Novartis, Pfizer, Pharmacyclics, and Roche; and has received non-financial support from NIHR RM/ICR Biomedical Research Centre for Cancer. JRA is an employee of Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA. JM and MJ are employees and stockholders of Incyte. SJD is an employee of Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA and stockholder of Merck & Co., Inc., Kenilworth, NJ, USA. TCM has served as a consultant/advisor for Bristol-Myers Squibb, Incyte, Merck, and Novartis. Ethical Approval: The study was conducted in accordance with the protocol, Declaration of Helsinki, and International Council for Harmonisation guidelines for Good Clinical Practice. The protocol and amendments were approved by the institutional review boards or independent ethics committees of participating institutions. All patients provided written informed consent.

Key Points Question Does duration of response (DOR), a rigorous metric combining both tumor responses and duration, better inform decisions about continuing or discontinuing before starting phase 3 immuno-oncology clinical trials? Findings This simulated modeling study, which was based on simulated randomized phase 2 trials that resampled patients from completed randomized phase 3 trials of immune checkpoint inhibitors, found that restricted mean DOR consistently outperformed progression-free survival and objective response rate in correctly estimating positive overall survival benefits without inflating type I errors. Meaning These findings suggest that restricted mean DOR may be a sensitive and informative early efficacy end point in randomized phase 2 trials in immuno-oncology., This simulated modeling study examines whether using restricted mean duration of response in phase 2 trials can better inform decisions about continuing or discontinuing before starting phase 3 immuno-oncology clinical trials compared with progression-free survival and objective response rate., Importance Phase 2 trials and early efficacy end points play a crucial role in informing decisions about whether to continue to phase 3 trials. Conventional end points, such as objective response rate (ORR) and progression-free survival (PFS), have demonstrated inconsistent associations with overall survival (OS) benefits in immune checkpoint inhibitor (ICI) trials. Restricted mean duration of response (DOR) is a rigorous metric that combines both response status and duration information. However, its utility in clinical development has not been comprehensively explored. Objective To determine whether using restricted mean DOR in phase 2 trials can advance promising regimens to phase 3 trials sooner and eliminate unfavorable regimens earlier and with a higher degree of confidence compared with PFS and ORR. Design, Setting, and Participants This simulated modeling study randomized phase 2 screening trials by resampling 1376 patients from 2 completed randomized phase 3 trials of ICIs. Data were analyzed from August 2019 to July 2020. Exposures Use of ICIs. Main Outcomes and Measures Restricted mean DOR, PFS, ORR, and OS were estimated and compared between groups. Three scenarios were considered: (1) significant differences in OS, PFS, and ORR; (2) significant differences in OS and noticeable differences in ORR but not PFS; and (3) no differences in OS, PFS, or ORR. For each setting, 5000 randomized phase 2 trials with different sample sizes were simulated, with additional censoring applied to mimic staggered accruals and ensure fair comparisons between different analysis methods. Probabilities of concluding positive phase 2 trials using PFS, ORR, and DOR were summarized and compared. Results The restricted mean DOR difference correctly estimated a positive OS benefit more frequently than did the ORR or PFS tests, across different sample sizes, significance levels, and censoring levels evaluated. When both OS and PFS differed, the ranges of true-positive or power rates were 79.2% to 98.7% for DOR, 56.3% to 93.2% for PFS, and 67.0% to 96.0% for ORR. When OS differed but PFS did not, the ranges of power rates were 24.0% to 76.0% for DOR, 3.0% to 19.0% for PFS, and 10.5% to 38.0% for ORR. When OS was similar, the false-positive rate of restricted mean DOR test was close to the chosen significance level. Conclusions and Relevance These findings suggest that restricted mean DOR in randomized phase 2 trials is potentially more sensitive and useful than PFS and ORR in estimating the subsequent phase 3 conclusions and, thus, may be considered to complementarily facilitate decision-making in future clinical development.

e21511 Background: Pembro as 2L therapy was well tolerated and had clinically meaningful antitumor activity in Chinese pts with advanced melanoma at first analysis of the phase 1b KEYNOTE-151 study. At median FU of 7.9 mo, ORR was 16.7% (1 complete response [CR]; 16 partial response [PR]), DCR was 38.2%, median DOR was 8.4 mo, median PFS was 2.8 mo, and median OS was 12.1 mo. Any grade and grade 3/4 treatment-related adverse events (TRAEs) occurred in 84.5% and 8.7% of pts, respectively. However, long-term efficacy and safety of 2L pembro in Chinese pts with advanced melanoma are unknown. Results from 3 y of FU are presented. Methods: Eligible pts were ≥18 y, of Chinese descent, had histologically confirmed locally advanced or metastatic melanoma, and had disease progression on or after first line therapy. Pts received pembro 2 mg/kg IV Q3W for ≤35 cycles. Eligible pts who discontinued pembro with stable disease or better could receive ≤17 additional cycles of pembro (second course) upon disease progression. Primary endpoints were safety and ORR per RECIST 1.1 by blinded independent central review (BICR). Secondary endpoints included DOR and PFS per RECIST 1.1 by BICR; ORR, DOR, and PFS per irRECIST by BICR; and OS. ORR was based on the exact binomial method; DOR, PFS, and OS analyses used the Kaplan-Meier method. The full analysis set (FAS) comprised all allocated pts who received ≥1 pembro dose and had baseline data for relevant analyses. Results: Of 103 enrolled pts, 43% were male, 51% had PD-L1 positive tumors, and 80% had BRAF wild-type tumors; median age was 52 y (range, 22-77). The FAS had 102 pts. Median time from first dose to database cutoff was 44.6 mo (IQR, 39.1-46.2). At database cutoff (July 13, 2020), 14 pts (13.5%) had completed treatment, 89 pts (86.4%) had discontinued. Any grade TRAEs occurred in 88 pts (85.4%); most commonly hypothyroidism (n = 27; 26.2%), increased ALT (n = 24; 23.3%), and hypertriglyceridemia (n = 23; 22.3%), all grade 1/2. Grade 3-5 TRAEs occurred in 13 pts (12.6%). Immune-mediated AEs and infusion reactions occurred in 35 pts (34.0%); most commonly grade 1/2 hypothyroidism (n = 27; 26.2%). 3 pts discontinued pembro because of a TRAE; none died because of a TRAE. ORR per RECIST 1.1 was 17.6% (95% CI 10.8-26.4; 1 CR/17 PR); DCR was 38.2% (95% CI 28.8-48.4). Median DOR per RECIST 1.1 was 13.8 mo (range, 2.7-37.4+); 1 pt had response duration ≥36 mo. Median PFS per RECIST 1.1 was 2.8 mo (95% CI 2.7-3.5); 36-mo PFS rate was 5.0%. ORR, DOR, and PFS were similar per RECIST 1.1 and irRECIST. Median OS was 13.2 mo (95% CI 10.4-16.5); 36-mo OS rate, 22.3%.1 pt completed the first and second courses of pembro and had investigator-confirmed CR. Conclusions: 2L pembro was well tolerated and continued to provide durable responses and clinically meaningful antitumor activity in Chinese pts with advanced melanoma. These results further support use of 2L pembro in Chinese pts with advanced melanoma. Clinical trial information: NCT02821000.

9504 Background: Initial results of the open-label, single-arm, phase 2 LEAP-004 study (NCT03776136) showed that len and pembro in combination had promising efficacy and manageable safety in pts with unresectable stage III-IV melanoma and confirmed PD on a PD-(L)1 inhibitor given alone or in combination. ORR was 21.4% with a 6.3-mo median DOR; ORR was 31.0% in patients with PD on prior anti–PD-1 + anti–CTLA-4. We present updated data from LEAP-004 and additional ORR subgroup analyses. Methods: Eligible pts with PD confirmed per iRECIST within 12 wk of the last dose of a PD-(L)1 inhibitor given alone or with anti–CTLA-4 or other therapies for ≥2 doses received len 20 mg/d once daily plus ≤35 doses of pembro 200 mg Q3W until PD or unacceptable toxicity. Primary end point is ORR per RECIST v1.1 by blinded independent central review (BICR). Secondary end points are PFS and DOR per RECIST v1.1 by BICR, OS, and safety. ORR was calculated for pts with PD on prior anti–PD-1 + anti–CTLA-4, pts whose only prior anti–PD-(L)1 was in the adjuvant setting, pts with primary resistance (ie, best response of SD or PD to prior anti–PD-(L)1 in the advanced setting) and pts with secondary resistance (ie, PD following best response of CR or PR on prior anti–PD-(L)1 in the advanced setting). Results: 103 pts were enrolled. Median age was 63 y, 68.0% of pts had stage M1c/M1d disease, 55.3% had LDH > ULN (20.4% ≥2 × ULN), 58.3% received ≥2 prior treatments, 94.2% received therapy for advanced disease, and 32.0% received BRAF ± MEK inhibition. With median study follow-up of 15.3 mo (range 12.1-19.0), 17.5% of pts were still receiving study drug. ORR by BICR remained 21.4% (95% CI 13.9-30.5), although the number of CRs increased from 2 to 3. DCR was 66.0%. Median DOR increased to 8.2 mo, and the KM estimate of DOR ≥9 mo was 37.2%. ORR was 33.3% in pts with PD on prior anti–PD-1 + anti–CTLA-4 (n = 30), 18.2% in pts whose only prior anti–PD-1/L1 was in the adjuvant setting (n = 11), 22.6% in pts with primary resistance (n = 62), and 22.7% in pts with secondary resistance (n = 22). Median (95% CI) PFS and OS in the total population were 4.2 mo (3.8-7.1) and 14.0 mo (95% CI 10.8-NR); 12-mo PFS and OS estimates were 17.8% and 54.5%. Incidence of treatment-related AEs was as follows: 96.1% any grade, 45.6% grade 3-4, 1.0% grade 5 (decreased platelet count), 7.8% led to discontinuation of len and/or pembro, and 56.3% led to len dose reduction. Conclusions: The combination of len and pembro continues to show clinically meaningful, durable responses in pts with advanced MEL with confirmed progression on a prior PD-(L)1 inhibitor, including those with PD on anti–PD-1 + anti–CTLA-4 therapy, and regardless of primary or secondary resistance to prior anti–PD-(L)1 therapy. The safety profile was consistent with prior studies of len + pembro. These data support len + pembro as a potential regimen for this population of high unmet need. Clinical trial information: NCT03776136.

Aim: To explore factors associated with pembrolizumab (PEMBRO) versus ipilimumab + nivolumab (IPI+NIVO) selection in advanced melanoma. Materials & methods: Total of 12 academic and satellite clinics contributed to this study. Descriptive and logistic regression analyses were conducted to explore associations between clinical characteristics and treatment choice. Results: Total of 400 patients were included: 200 PEMBRO and 200 IPI+NIVO. Patients were significantly more likely to receive PEMBRO versus IPI+NIVO if they had poorer Eastern Cooperative Oncology Group score, 2–4 versus 0–1 (odds ratio [OR]: 6.6; 95% CI: 3.0–14.7), if they were PD-L1 positive (OR: 4.5; 95% CI: 1.9–10.4) or had BRAF wild-type tumor (OR: 2.2; 95% CI: 1.4–3.6). Conclusion: Patient factors are significantly associated with treatment selection in advanced melanoma. Outcomes comparisons should take this into consideration.

Background Vorinostat combined with retinoids produces additive antitumor effects in preclinical studies of neuroblastoma. Higher systemic exposures of vorinostat than achieved in pediatric phase I trials with continuous daily dosing are necessary for in vivo increased histone acetylation and cytotoxic activity. We conducted a phase I trial in children with relapsed/refractory neuroblastoma to determine the maximum tolerated dose (MTD) of vorinostat on an interrupted schedule, escalating beyond the previously identified pediatric MTD. Methods Isotretinoin (cis-13-retinoic acid) 80 mg/m2 /dose was administered by mouth twice daily on days 1-14 in combination with escalating doses of daily vorinostat up to 430 mg/m2 /dose (days 1-4; 8-11) in each 28-day cycle using the standard 3 + 3 design. Vorinostat pharmacokinetic testing and histone acetylation assays were performed. Results Twenty-nine patients with refractory or relapsed neuroblastoma were enrolled and 28 were evaluable for dose escalation decisions. Median number of cycles completed was two (range 1-15); 11 patients received four or more cycles. Three patients experienced cycle 1 dose-limiting toxicities. A total of 18 patients experienced grade 3/4 toxicities related to study therapy. The maximum intended dose of vorinostat (430 mg/m2 /day, days 1-4; 8-11) was tolerable and led to increased histone acetylation in surrogate tissues when compared to lower doses of vorinostat (P = 0.009). No objective responses were seen. Conclusions Increased dose vorinostat (430 mg/m2 /day) on an interrupted schedule is tolerable in combination with isotretinoin. This dose led to increased vorinostat exposures and demonstrated increased histone acetylation. Prolonged stable disease in patients with minimal residual disease warrants further investigation.

Summary Background Pembrolizumab is approved for the treatment of advanced cancer in adults; however, no information is available on safety and efficacy in paediatric patients. We aimed to establish the recommended phase 2 dose of pembrolizumab and its safety and antitumour activity in advanced paediatric cancer. Methods KEYNOTE-051 is an ongoing phase 1–2 open-label trial. In this interim analysis, children aged 6 months to 17 years were recruited at 30 hospitals located in Australia, Brazil, Canada, France, Germany, Israel, Italy, South Korea, Sweden, the UK, and the USA. Patients with melanoma or a centrally confirmed, PD-L1-positive, relapsed or refractory solid tumour or lymphoma, and a Lansky Play/Karnofsky Performance status score of 50 or higher, received intravenous pembrolizumab at an initial dose of 2 mg/kg every 3 weeks. Pharmacokinetics and dose-limiting toxicities were used to establish the recommended phase 2 dose, and the safety and antitumour activity of this dose were assessed. Primary endpoints were determination of dose-limiting toxicities at the maximum administered dose, safety and tolerability, and the proportion of patients with objective response to pembrolizumab for each tumour type according to the Response Evaluation Criteria in Solid Tumours version 1.1 or the International Neuroblastoma Response Criteria. Safety and efficacy were assessed in all treated patients who received at least one dose of pembrolizumab. Separate reporting of the cohort of patients with relapsed or refractory classical Hodgkin lymphoma was a post-hoc decision. The data cutoff for this interim analysis was Sept 3, 2018. This trial is still enrolling patients and is registered with ClinicalTrials.gov , number NCT02332668 . Findings Of 863 patients screened between March 23, 2015, and Sept 3, 2018, 796 had tumours that were evaluable for PD-L1 expression (278 [35%] were PD-L1-positive); 155 eligible patients were enrolled and 154 had at least one dose of pembrolizumab. The median age of the enrolled patients was 13 years (IQR 8–15). Median follow-up was 8·6 months (IQR 2·5–16·4). No dose-limiting toxicities were reported in phase 1, and pembrolizumab plasma concentrations were consistent with those previously reported in adults; the recommended phase 2 dose was therefore established as 2 mg/kg every 3 weeks. Of the 154 patients treated, 69 (45%) experienced grade 3–5 adverse events, most commonly anaemia in 14 (9%) patients and decreased lymphocyte count in nine (6%) patients. 13 (8%) of the 154 patients had grade 3–5 treatment-related adverse events, most commonly decreased lymphocyte count in three (2%) patients and anaemia in two (1%) patients. 14 (9%) patients had serious treatment-related adverse events, most commonly pyrexia (four [3%]), and hypertension and pleural effusion (two [1%] each). Four patients (3%) discontinued treatment because of treatment-related adverse events, and two (1%) died (one due to pulmonary oedema and one due to pleural effusion and pneumonitis). Of 15 patients with relapsed or refractory Hodgkin lymphoma, two had complete and seven had partial responses; thus, nine patients achieved an objective response (60·0%; 95% CI 32·3–83·7). Of 136 patients with solid tumours and other lymphomas, eight had partial responses (two patients each with adrenocortical carcinoma and mesothelioma, and one patient each with malignant ganglioglioma, epithelioid sarcoma, lymphoepithelial carcinoma, and malignant rhabdoid tumour); the proportion of patients with an objective response was 5·9% (95% CI 2·6–11·3). Interpretation Pembrolizumab was well tolerated and showed encouraging antitumour activity in paediatric patients with relapsed or refractory Hodgkin lymphoma, consistent with experience in adult patients. Pembrolizumab had low antitumour activity in the majority of paediatric tumour types, and responses were observed in only a few rare PD-L1-positive tumour types, suggesting that PD-L1 expression alone is not sufficient as a biomarker for the selection of paediatric patients who are likely to respond to PD-1 checkpoint inhibitors. Final results of KEYNOTE-051, expected by September, 2022, with the possibility for extension, will report further on the activity of pembrolizumab in Hodgkin lymphoma, microsatellite instability-high tumours, and melanoma. Funding Merck Sharp & Dohme, a subsidiary of Merck & Co.

Here we report a phase 1b clinical trial testing the impact of oncolytic virotherapy with talimogene laherparepvec on cytotoxic Tcell infiltration and therapeutic efficacy of the anti-PD-1 antibody pembrolizumab. Twenty-one patients with advanced melanoma were treated with talimogene laherparepvec followed by combination therapy with pembrolizumab. Therapy was generally well tolerated, with fatigue, fevers, and chills as the most common adverse events. No dose-limiting toxicities occurred. Confirmed objective response rate was 62%, with a complete response rate of 33% per immune-related response criteria. Patients who responded to combination therapy had increased CD8+ Tcells, elevated PD-L1 protein expression, as well as IFN-γ gene expression on several cell subsets in tumors after talimogene laherparepvec treatment. Response tocombination therapy did not appear to be associated with baseline CD8+ Tcell infiltration or baseline IFN-γ signature. These findings suggest that oncolytic virotherapy may improve the efficacy of anti-PD-1 therapy by changing the tumor microenvironment. VIDEO ABSTRACT.

Background Pembro, a PD-1 inhibitor, has shown effective antitumor activity, durable responses, and survival benefit in pts with advanced melanoma. Len—a potent inhibitor of VEGF receptors 1-3, FGF receptors 1-4, PDGF receptor α, RET, and KIT—plus a PD-1 inhibitor showed superior antitumor efficacy to either agent alone in a murine tumor model. Len + pembro showed antitumor activity and was well tolerated in pts with advanced melanoma in the phase Ib/II KEYNOTE-146 trial. LEAP-003 will compare the efficacy and safety of pembro ± len in advanced melanoma (NCT03820986). Trial design Eligibility criteria include ≥18 y, histologically/cytologically confirmed unresectable untreated stage III-IV melanoma, documented BRAFV600 status, ECOG performance status 0/1, toxicity resolution from most recent therapy, and provision of baseline tumor sample. Prior first-line standard of care targeted therapy allowed only if pt has BRAFV600-mutant disease. Prior targeted therapy or immunotherapy (as adjuvant/neoadjuvant) allowed if relapse did not occur during treatment or ≤ 6 mo after discontinuation. Pts will be randomized 1:1 to pembro 200 mg every 3 weeks (Q3W) IV plus len 20 mg or placebo QD PO. Randomization will be stratified by BRAF status (mutant/WT), prior adjuvant therapy (PD-1 inhibitor, yes/no), geographic region (China, yes/no). Pembro will continue for up to ∼2 y; len or placebo may continue beyond 2 y in cases of clinical benefit, until progression, unacceptable toxicity, or investigator/pt decision. Response will be assessed per RECIST v1.1 Q9W until wk 54, Q12W until wk 102, and Q24W thereafter. Pts with a CR can discontinue treatment after ≥24 wk of pembro and ≥2 pembro doses after initial CR. Eligible pts can continue treatment beyond initial RECIST-defined PD. AEs will be assessed for ≤90 d and graded per NCI CTCAE v4.0. Survival follow-up will be Q12W. Primary end points are PFS by blinded independent central review (BICR) per modified RECIST v1.1 (max target lesions: 10; 5 per organ) and OS. Secondary end points are ORR and DOR (by BICR per modified RECIST v1.1), safety, and pt-reported health outcomes. Exploratory biomarker and PK analyses of len plus pembro are planned. Clinical trial identification NCT03820986; release date: January 29, 2019. Editorial acknowledgement Doyel Mitra, PhD, CMPP, and Harleigh E. Willmott, PhD, CMPP, of the ApotheCom pembrolizumab team (Yardley, PA, USA). Legal entity responsible for the study Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA. Funding Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA. Disclosure A.M.M. Eggermont: Honoraria (self): Actelion, BMS, GSK, Ellipses, Incyte, IO Biotech, IsaPhamaceuticals, MSD, Novartis, Pfizer, Sanofi, Sellas, SkylineDx; Advisory / Consultancy: Actelion, BMS, GSK, Ellipses, Incyte, IO Biotech, IsaPhamaceuticals, MSD, Novartis, Pfizer, Sanofi, Sellas, SkylineDx; Speaker Bureau / Expert testimony: MSD. M.S. Carlino: Honoraria (self): MSD, BMS; Advisory / Consultancy: MSD, BMS, Novartis, Roche, Merck, Pierre Fabre. A. Hauschild: Honoraria (self): Amgen, BMS, MSD/Merck, Novartis, Pierre Fabre, Provectus, Regeneron, Roche, Sanofi-Genzyme; Honoraria (institution), Support for clinical trials: Amgen, BMS, MerckSerono, MSD/Merck, Novartis, Philogen, Pierre Fabre, Provectus, Regeneron, Roche, Sanofi-Genzyme; Advisory / Consultancy: Amgen, BMS, MerckSerono, MSD/Merck, Novartis, Philogen, Pierre Fabre, Provectus, Regeneron, Roche, OncoSec, Sanofi-Genzyme, Sun Pharma. P.A. Ascierto: Advisory / Consultancy: BMS, Roche-Genentech, MSD, Array, Novartis, Merck Serono, Pierre Fabre, Incyte, Genmab, Newlink Genetics, MedImmune, AstraZeneca, Syndax, Sun Pharma, Sanofi, Idera, Ultimovacs, Sandoz, Immunocore, 4SC; Research grant / Funding (self): BMS, Roche-Genentech, Array; Travel / Accommodation / Expenses: MSD. A. Arance: Advisory / Consultancy: BMS, MSD, Roche, Novartis, Merck; Travel / Accommodation / Expenses: BMS, MSD, Roche, Novartis, Merck. A. Daud: Advisory / Consultancy: Merck, Pfizer, BMS, Genentech, Incyte, Novartis; Shareholder / Stockholder / Stock options: SQZ; Research grant / Funding (self): BMS, Pfizer, Incyte, Checkmate, Merck. S.J. O’Day: Advisory / Consultancy: Biothera, BMS, Merck, RadImmune, ImaginAB; Speaker Bureau / Expert testimony: BMS; Travel / Accommodation / Expenses: Biothera, BMS, Merck, RadImmune, ImaginAB; Research grant / Funding (institution): Amgen, Biothera, Exicure, Genocea, Incyte, Oncothereapeutics, Ultimovacs, Viralytics. M.H. Taylor: Honoraria (self): BMS, Eisai Inc, Array Biopharma, Arqule, Blueprint Medicines, Bayer, Loxo Oncology, Novartis; Advisory / Consultancy: BMS, Eisai Inc, Array Biopharma, Arqule, Blueprint Medicines, Bayer, Loxo Oncology, Novartis; Speaker Bureau / Expert testimony: BMS, Eisai Inc. A. Smith: Full / Part-time employment: Eisai. A. Rodgers: Full / Part-time employment: Merck & Co., Inc. B. Homet Moreno: Shareholder / Stockholder / Stock options, Full / Part-time employment: Merck & Co., Inc. S.J. Diede: Shareholder / Stockholder / Stock options, Full / Part-time employment: Merck & Co., Inc. H. Kluger: Research grant / Funding (institution): Merck, BMS, Apexigen; Honoraria (self): Regeneron, Alexion, Prometheus, Corvus, Nektar, Biodesix, Roche/Genentech, Pfizer, Iovance, Immunocore, Celldex, Array BioPharma.

Introduction: Pembro significantly improved OS vs ipi in advanced melanoma in the KEYNOTE-006 study (NCT01866319). We present outcomes from the 5-year follow-up of this study−the longest to date in a randomized phase 3 trial of pembro in advanced cancer. Long-term follow-up for pts completing 2 years of pembro and data for pts treated with a second course (2nd course) of pembro are also reported. Methods: Eligible pts (N=834) were randomly assigned (1:1:1) to pembro 10 mg/kg Q2W or Q3W for up to 2 years or ipi 3 mg/kg Q3W for 4 doses. Eligible pts who completed pembro or stopped for CR and then progressed could receive an additional 12 mo of pembro if they met inclusion criteria. End points included OS and ORR per irRC by investigator review. Pembro completion was defined as discontinuation with CR, PR, or SD after ≥94 weeks of pembro. Results were pooled from the 2 pembro arms. Results: At data cutoff (Dec 3, 2018), median follow-up of surviving pts was 57.7 mo (range, 0.03-62.1). Median OS (95% CI) was 32.7 mo (24.5-41.6) in the combined pembro arms (n=556) and 15.9 mo (13.3-22.0) in the ipi arm (n=278) (HR, 0.73). Five-year OS rates (95% CI) were estimated to be 38.7% (34.2-43.1) and 31.0% (25.3-36.9), respectively. For pts receiving first-line pembro, median OS (95% CI) was 38.7 mo (27.3-50.7) in the combined pembro arms (n=368) and 17.1 mo (13.8-26.2) in the ipi arm (n=181) (HR, 0.73); 5-year OS rates (95% CI) were estimated to be 43.2% (38.0-48.3) and 33.0% (25.8-40.3), respectively. A total of 103 (18.5%) pts completed 2 years of pembro; median survival follow-up from pembro completion was 34.5 mo; OS rate at 36 mo was 93.8%. Of the 103 pts, 76 were progression-free and 27 had PD. Median time from pembro end to progression was 16.8 mo (range, 0.99-33.9). Thirteen pts received 2nd course pembro; best overall response (BOR) in 1st course was 6 CR, 6 PR, and 1 SD. Median duration of 2nd-course pembro was 9.7 mo; BOR on 2nd course was 3 CR, 4 PR, 3 SD, and 1 PD (response assessment was pending for 2 pts). All 3 pts with 2nd-course CR and 2 of 4 with PR had ongoing response; the remaining 2 pts who had 2nd-course PR subsequently progressed. Four pts discontinued 2nd-course treatment before 12 mo (2 due to PD, 1 due to G2 interstitial pneumonia, and 1 due to physician decision). Six pts had grade1/2 TRAEs during 2nd-course pembro; there were no grade 3/4 TRAEs or deaths. Conclusions: Pembro continued to show improved OS vs ipi in 5-year follow-up of pts with advanced melanoma with 43.2% estimated to be alive at 5 years versus 33.0% with ipi. Almost one-fifth of pts completed 2 years of pembro, and 93.8% are estimated to be alive 3 years after pembro completion. Second-course pembro treatment was generally well tolerated and provided additional antitumor activity. These results confirm that 2-year pembro is an effective treatment for pts with advanced melanoma. Citation Format: Caroline Robert, Jacob Schachter, Georgina V. Long, Ana Arance, Jean-Jacques Grob, Laurent Mortier, Adil Daud, Matteo S. Carlino, Catriona McNeil, Michal Lotem, James Larkin, Paul Lorigan, Bart Neyns, Christian U. Blank, Omid Hamid, Teresa M. Petrella, James Anderson, Clemens Krepler, Scott J. Diede, Antoni Ribas. 5-year survival and other long-term outcomes from KEYNOTE-006 study of pembrolizumab (pembro) for ipilimumab (ipi)-naive advanced melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT188.

Pembrolizumab has been approved in the United States for treating advanced melanoma for >4 years. We examined real-world pembrolizumab use and associated outcomes in US oncology clinical practices, including patients who would not be eligible for clinical trials.Flatiron Health longitudinal

9532 Background: Both pembrolizumab (PEMBRO) and combination ipilimumab + nivolumab (IPI+NIVO) are FDA-approved immunotherapies for advanced melanoma (AM). These two treatment regimens have different toxicity profiles which may impact health care resource utilization (HCRU). Our aim was to compare real-world risk of hospitalization and emergency department (ED) visits within 12 months of starting the two treatment regimens. Methods: A retrospective cohort study was conducted in patients ≥18 years old with AM initiating PEMBRO or IPI+NIVO between Jan 1, 2016 – Dec 30, 2017. Patients were identified from 12 US academic medical centers and affiliated satellite clinics. Data were abstracted through chart review. All-cause hospitalizations or ED visits and the rates per patient per month (PPPM) through 12 months of follow-up were calculated. Utilization was compared between PEMRBO and IPI+NIVO using multivariate logistic regression analysis. Results: 400 patients were included, 200 each PEMBRO and IPI+NIVO with mean (SD) follow-up time of 10 (3) and 10 (4) months, respectively. The PEMBRO cohort had poorer Eastern Cooperative Group (ECOG) performance status at treatment start, 71% ECOG 0 or 1 vs 88% (p < .001); more diabetes, 21% vs 13% (p = .045); a trend towards more heart disease, 18% vs 12% (p = .067); were more likely to be PD-L1 expression positive, 77% vs 63% (p = .011); and less likely to harbor a BRAF mutation, 35% vs 50% (p = .003). The proportion with at least one hospitalization through 12 months was 17% PEMBRO vs 24% IPI+NIVO. Less than 2% of patients had more than one admission and none had more than two, regardless of cohort. Unadjusted mean (SD) PPPM hospitalizations were .016 (.037) for PEMBRO and .020 (.038) for IPI+NIVO. The adjusted odds ratio for any hospitalization with PEMBRO was 0.55 (95% CI .31, .97; p = .039) vs. IPI+NIVO. ED visits occurred in 18% vs 21% in PEMBRO and IPI+NIVO respectively, with no difference in covariate-adjusted analysis (p = .147). Conclusions: Patients receiving PEMBRO had a significantly lower probability of hospitalization and similar probability of ER visits compared with IPI+NIVO in the real world through 12 months.

e21031 Background: Pembrolizumab (PEM), a humanized antibody targeting programmed death-1 receptor, has been approved by FDA for the treatment of patients (pts) with advanced melanoma (AM) in the US since 2014. Real-world (RW) data supports the clinical effectiveness of 1L use of PEM, but there is limited information of PEM later line use. The study examined the RW outcomes of pts treated with PEM who have failed prior lines of therapy in US oncology clinical practices. Methods: Flatiron Health longitudinal database was used to identify adult pts with AM who received ≥1 dose of PEM in second line (2L) or later (3L+) between September 4, 2014 and May 31, 2017. Pts were followed up to May 31, 2018. Pts in clinical trials were excluded. Pt demographic, treatment, and clinical characteristics were described. Time on treatment (ToT) and overall survival (OS) were analyzed using the Kaplan Meier (KM) method, with the first dose of PEM as the starting point. Results: Two hundred thirty-six pts were included in the analysis, of which there were 171 2L and 65 3L+. Overall, median age at PEM initiation was 66 years; most were male (66.1%) and Caucasian (95.4%). 41.1% of pts’ tumors were confirmed BRAF mutant; 49.6% of pts’ tumors were confirmed BRAF wildtype; the rest was not tested or indeterminate. When data were available, 26.2% had an elevated lactate dehydrogenase (> ULN), 24.6% had brain metastases, and 25.5% had an ECOG performance status of > 1. At the time of analysis, pts were followed for a median of 12.5 months (mo, range, 0.1-44.6). Overall median ToT was 4.4 mo (95% CI, 3.5-5.3), with 4.7 and 4.4 mo in 2L and 3L+, respectively. Overall median OS was 16.8 mo (95% CI, 12.2-25.9), with 16.8 and 18.9 mo for 2L and 3L+ respectively. 1-year and 2-year survival, using the KM method, was 58.0% (95% CI, 51.2-64.1; 2L, 57.4%; 3L+, 59.6%) and 44.7% (95% CI, 37.9-51.3; 2L, 44.3%; 3L+, 46.1%) respectively. Conclusions: The study reports RW use of PEM in a large cohort of pts with AM who have failed initial therapy in US oncology clinical practices, with a heterogeneous study population compared to clinical trials. The findings of OS based on RW use suggest PEM is an effective treatment option for patients in later lines of therapy.

TPS9594 Background: Pembro, a PD-1 inhibitor, has shown effective antitumor activity, deep and durable responses, and survival benefit in treatment-naive pts and those with previously treated metastatic melanoma. Len, a potent inhibitor of VEGF receptors 1-3, FGF receptors 1-4, PDGF receptor α, RET, and KIT, combined with a PD-1 inhibitor showed antitumor activity superior to either agent alone in preclinical models of colorectal and lung cancer. Additionally, len plus pembro showed anti-tumor activity and was well-tolerated (24-wk ORR, 47.6%; TRAE: gr 3/4, 67%; gr 5, 0%) in pts with advanced melanoma previously treated with 0-2 therapies in the phase 1b/2 KEYNOTE-146 trial. The efficacy and safety of len plus pembro combination therapy will be evaluated in an open-label, phase 2 trial of pts with advanced melanoma that progressed on PD-1/PD-L1 inhibitor therapy (NCT03776136). Methods: Key inclusion criteria: age ≥18 years, histologically/cytologically confirmed unresectable stage III-IV melanoma that progressed (per iRECIST) within 12 weeks of last dose of an approved PD-1/PD-L1 inhibitor therapy (≥2 doses as monotherapy or combined with other therapies), measurable disease, ECOG PS 0/1, no active autoimmune disease, and adequate organ function. Pts must provide a baseline tumor sample. Pts will receive len 20 mg/day orally plus pembro 200 mg IV Q3W for approximately 2 years (35 doses of pembro), after which they may receive len alone until PD or unacceptable toxicity. Response will be assessed per RECIST v1.1 based on blinded independent central review (BICR) Q9W until week 54, Q12W until week 102, and Q24W thereafter. Pts with CR may discontinue treatment after ≥24 weeks of therapy; eligible pts may continue treatment beyond initial RECIST- or iRECIST-defined PD. AEs will be assessed throughout treatment and for 90 days (120 days for serious AEs) after last dose and graded per NCI CTCAE v4.0. Pts will be followed-up for survival status Q12W. The primary efficacy end point is ORR per modified RECIST v1.1 (BICR). Key secondary end points are PFS and DOR per modified RECIST v1.1 (BICR), OS, and safety; an exploratory biomarker analysis is planned. Clinical trial information: NCT03776136.

e21004 Background: Pembrolizumab (PEMBRO) and combination ipilimumab + nivolumab (IPI+NIVO) are FDA-approved immunotherapies for advanced melanoma (AM). HRQoL was better maintained with PEMBRO vs IPI in KEYNOTE-006. CheckMate-067 reported no clinically meaningful HRQoL differences with IPI+NIVO vs IPI. As randomized trial data are lacking, we compared HRQoL outcomes in AM between PEMBRO and IPI+NIVO in real-world clinical settings. Methods: A prospective, observational study was conducted with sponsor blinded to sites, and sites blinded to sponsor; nine oncologists from 9 US academic centers and affiliated satellite clinics enrolled AM patients (pts) age ≥18 years initiating first-line PEMBRO or IPI+NIVO between June 2017 – March 2018. The European Organization for the Treatment of Cancer Quality of Life Questionnaire Core-30 (EORTC QLQ C30) and EQ-5D-5L were administered at baseline and weeks 6, 12, 18, and 24 following therapy. Least squared (LS) mean changes in HRQoL scores from baseline were compared using mixed-effects models for repeated measures, adjusting for baseline covariates. Results: A total of 225 PEMBRO and 187 IPI+NIVO pts were enrolled, with > 95% questionnaire completion rates through week 24. At baseline, PEMBRO pts were more likely > age 65 (49% vs 37%, p = .011), stage IV disease (92% vs 85%; p = .002), and higher comorbidity index (1.0 vs 0.6; p < .001) compared with IPI+NIVO pts. Adjusted EORTC global health status/quality of life (GHS) LS mean changes from baseline showed greater improvement with PEMBRO vs. IPI+NIVO at 12, 18 and 24 weeks. At week 24, PEMBRO pts achieved a 3.3-point improvement (95% CI = 0.8, 5.7) and IPI+NIVO pts had no significant change (1.0, 95% CI = -1.6, 3.5), with a LS mean difference of 2.3 points (p = .037; 95% CI = 0.14, 4.51). At week 24, the EQ-5D visual analogue scale increased 1.0 (95% CI, -1.2, 3.2) for PEMBRO vs IPI+NIVO which decreased 0.9 (95% CI = -3.2, 1.3), with a statistically significant LS mean difference of 2.0 (95% CI = 0.4, 3.9; p = .045). Conclusions: Results from 2 measures suggest HRQoL was maintained vs. baseline in both PEMBRO and IPI+NIVO pts, with a significant between-group difference favoring PEMBRO in GHS over 24 weeks.

Genetic and epigenetic alterations are essential for the initiation and progression of human cancer. We previously reported that primary human medulloblastomas showed extensive cancer-specific CpG island DNA hypermethylation in critical developmental pathways. To determine whether genetically engineered mouse models (GEMMs) of medulloblastoma have comparable epigenetic changes, we assessed genome-wide DNA methylation in three mouse models of medulloblastoma. In contrast to human samples, very few loci with cancer-specific DNA hypermethylation were detected, and in almost all cases the degree of methylation was relatively modest compared with the dense hypermethylation in the human cancers. To determine if this finding was common to other GEMMs, we examined a Burkitt lymphoma and breast cancer model and did not detect promoter CpG island DNA hypermethylation, suggesting that human cancers and at least some GEMMs are fundamentally different with respect to this epigenetic modification. These findings provide an opportunity to both better understand the mechanism of aberrant DNA methylation in human cancer and construct better GEMMs to serve as preclinical platforms for therapy development.

Rhabdomyosarcoma is a pediatric tumor of skeletal muscle that expresses the myogenic basic helix-loop-helix protein MyoD but fails to undergo terminal differentiation. Prior work has determined that DNA binding by MyoD occurs in the tumor cells, but myogenic targets fail to activate. Using MyoD chromatin immunoprecipitation coupled to high-throughput sequencing and gene expression analysis in both primary human muscle cells and RD rhabdomyosarcoma cells, we demonstrate that MyoD binds in a similar genome-wide pattern in both tumor and normal cells but binds poorly at a subset of myogenic genes that fail to activate in the tumor cells. Binding differences are found both across genomic regions and locally at specific sites that are associated with binding motifs for RUNX1, MEF2C, JDP2, and NFIC. These factors are expressed at lower levels in RD cells than muscle cells and rescue myogenesis when expressed in RD cells. MEF2C is located in a genomic region that exhibits poor MyoD binding in RD cells, whereas JDP2 exhibits local DNA hypermethylation in its promoter in both RD cells and primary tumor samples. These results demonstrate that regional and local silencing of differentiation factors contributes to the differentiation defect in rhabdomyosarcomas.

O1 IL-15 primes an mTOR-regulated gene-expression program to prolong anti-tumor capacity of human natural killer cells #### Andreas Lundqvist1, Vincent van Hoef1, Xiaonan Zhang1, Erik Wennerberg2, Julie Lorent1, Kristina Witt1, Laia Masvidal Sanz1, Shuo Liang1, Shannon Murray3, Ola Larsson1

Rhabdomyosarcoma is the most common soft-tissue sarcoma in children. While cytogenetic abnormalities have been well characterized in this disease, aberrant epigenetic events such as DNA hypermethylation have not been described in genome-wide studies. We have analyzed the methylation status of 25,500 promoters in normal skeletal muscle, and in cell lines and tumor samples of embryonal and alveolar rhabdomyosarcoma from pediatric patients. We identified over 1,900 CpG islands that are hypermethylated in rhabdomyosarcomas relative to skeletal muscle. Genes involved in tissue development, differentiation, and oncogenesis such as DNAJA4, HES5, IRX1, BMP8A, GATA4, GATA6, ALX3, and P4HTM were hypermethylated in both RMS cell lines and primary samples, implicating aberrant DNA methylation in the pathogenesis of rhabdomyosarcoma. Furthermore, cluster analysis revealed embryonal and alveolar subtypes had distinct DNA methylation patterns, with the alveolar subtype being enriched in DNA hypermethylation of polycomb target genes. These results suggest that DNA methylation signatures may aid in the diagnosis and risk stratification of pediatric rhabdomyosarcoma and help identify new targets for therapy.

Introduction Le pembrolizumab est approuve dans plus de 50 pays pour le traitement des patients ayant un melanome avance. Nous presentons les donnees de survie a 3 ans pour les patients inclus dans l’essai de phase 1, Keynote-001 ( NCT01295827 ). De plus, nous avons etudie precisement les cinetiques de reponse et le devenir des patients ayant repondu completement au traitement. Patients et methodes Des patients pretraites ou non par ipilimumab ont ete inclus dans cet essai dans plusieurs cohortes explorant differentes doses de pembrolizumab : 2 ou 10 mg/kg toutes les 3 semaines ou 10 mg/kg toutes les 2 semaines. Les patients cliniquement stables pouvaient rester dans l’etude malgre une progression radiologique jusqu’a ce que cette progression soit confirmee. Les reponses ont ete evaluees selon les criteres Recist v1.1 toutes les 12 semaines. Resultats Six cent cinquante-cinq patients ont ete inclus, dont 24 % presentant une mutation de BRAFV600, 78 % de stade M1c, 75 % ayant recu plus d’une ligne de traitement systemique auparavant et 52 % ayant ete pretraites par ipilimumab. Apres un suivi median de 32 mois, le taux de survie estime a 3 ans etait de 40 % et la survie mediane de 23,8 mo (95 % CI, 20,2–29,0), avec des resultats similaires pour toutes les doses de pembrolizumab. Le taux de reponse objective etait stable a 33 % et 95 patients ont atteint une reponse complete qui persistait chez 89 % d’entre eux. Chez les 61 patients qui ont arrete le traitement pour reponse complete, seuls deux patients ont recidive apres une duree mediane sans traitement de 10 mois. Conclusion Le pembrolizumab confirme son benefice therapeutique chez les patients atteints de melanome metastatique avec une survie chez 40 % des patients apres 3 ans, et permet des reponses completes prolongees meme apres arret du traitement.