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PURPOSE The open-label, phase III POSEIDON study evaluated tremelimumab plus durvalumab and chemotherapy (T + D + CT) and durvalumab plus chemotherapy (D + CT) versus chemotherapy alone (CT) in first-line metastatic non–small-cell lung cancer (mNSCLC). METHODS Patients (n = 1,013) with EGFR/ ALK wild-type mNSCLC were randomly assigned (1:1:1) to tremelimumab 75 mg plus durvalumab 1,500 mg and platinum-based chemotherapy for up to four 21-day cycles, followed by durvalumab once every 4 weeks until progression and one additional tremelimumab dose; durvalumab plus chemotherapy for up to four 21-day cycles, followed by durvalumab once every 4 weeks until progression; or chemotherapy for up to six 21-day cycles (with or without maintenance pemetrexed; all arms). Primary end points were progression-free survival (PFS) and overall survival (OS) for D + CT versus CT. Key alpha-controlled secondary end points were PFS and OS for T + D + CT versus CT. RESULTS PFS was significantly improved with D + CT versus CT (hazard ratio [HR], 0.74; 95% CI, 0.62 to 0.89; P = .0009; median, 5.5 v 4.8 months); a trend for improved OS did not reach statistical significance (HR, 0.86; 95% CI, 0.72 to 1.02; P = .0758; median, 13.3 v 11.7 months; 24-month OS, 29.6% v 22.1%). PFS (HR, 0.72; 95% CI, 0.60 to 0.86; P = .0003; median, 6.2 v 4.8 months) and OS (HR, 0.77; 95% CI, 0.65 to 0.92; P = .0030; median, 14.0 v 11.7 months; 24-month OS, 32.9% v 22.1%) were significantly improved with T + D + CT versus CT. Treatment-related adverse events were maximum grade 3/4 in 51.8%, 44.6%, and 44.4% of patients receiving T + D + CT, D + CT, and CT, respectively; 15.5%, 14.1%, and 9.9%, respectively, discontinued treatment because of treatment-related adverse events. CONCLUSION D + CT significantly improved PFS versus CT. A limited course of tremelimumab added to durvalumab and chemotherapy significantly improved OS and PFS versus CT, without meaningful additional tolerability burden, representing a potential new option in first-line mNSCLC.

PURPOSE: IMpower133 (ClinicalTrials.gov identifier: NCT02763579 ), a randomized, double-blind, phase I/III study, demonstrated that adding atezolizumab (anti-programmed death-ligand 1 [PD-L1]) to carboplatin plus etoposide (CP/ET) for first-line (1L) treatment of extensive-stage small-cell lung cancer (ES-SCLC) resulted in significant improvement in overall survival (OS) and progression-free survival (PFS) versus placebo plus CP/ET. Updated OS, disease progression patterns, safety, and exploratory biomarkers (PD-L1, blood-based tumor mutational burden [bTMB]) are reported. PATIENTS AND METHODS: Patients with untreated ES-SCLC were randomly assigned 1:1 to receive four 21-day cycles of CP (area under the curve 5 mg per mL/min intravenously [IV], day 1) plus ET (100 mg/m2 IV, days 1-3) with atezolizumab (1,200 mg IV, day 1) or placebo, and then maintenance atezolizumab or placebo until unacceptable toxicity, disease progression, or loss of clinical benefit. Tumor specimens were collected; PD-L1 testing was not required for enrollment. The two primary end points, investigator-assessed PFS and OS, were statistically significant at the interim analysis. Updated OS and PFS and exploratory biomarker analyses were conducted. RESULTS: Patients received atezolizumab plus CP/ET (n = 201) or placebo plus CP/ET (n = 202). At the updated analysis, median follow-up for OS was 22.9 months; 302 deaths had occurred. Median OS was 12.3 and 10.3 months with atezolizumab plus CP/ET and placebo plus CP/ET, respectively (hazard ratio, 0.76; 95% CI, 0.60 to 0.95; descriptive P = .0154). At 18 months, 34.0% and 21.0% of patients were alive in atezolizumab plus CP/ET and placebo plus CP/ET arms, respectively. Patients derived benefit from the addition of atezolizumab, regardless of PD-L1 immunohistochemistry or bTMB status. CONCLUSION: Adding atezolizumab to CP/ET as 1L treatment for ES-SCLC continued to demonstrate improved OS and a tolerable safety profile at the updated analysis, confirming the regimen as a new standard of care. Exploratory analyses demonstrated treatment benefit independent of biomarker status.

e20578 Background: To investigate the impact of treatment patterns in inoperable stage III NSCLC following concurrent chemoradiotherapy with or without immune checkpoint inhibition (cCRT±ICI). Methods: Patients were stratified by treatment year and divided into three subgroups: A (2011–2014), B (2015–2017) and C (2018–2020). Patient- and treatment-related characteristics regarding to PFS and OS were analyzed. Survival parameters were calculated from the last day of thoracic radiotherapy (TRT). Results: 136 consecutive enrolled patients were included. Median follow-up (FU) was 35.7 months; median age was 66.9 years. All patients completed TRT to a total dose ≥60.0 Gy; Median radiotherapy planning target volume (PTV) was 700 cc (range: 172.5–2293.2). Thirty-six (26%) patients received ICI. Median PFS in subgroups A, B and C was 8.0, 8.2 and 26.3 months (p = 0.007). Median OS was 19.9 months, 23.4 months and not reached in subgroups A, B and C (p < 0.05). In subgroup C, median PFS was 14.2 vs. 26.3 months in patients treated with and without ICI. On multivariate analysis for the entire cohort, PTV > 700cc was a negative prognosticator of PFS (HR: 1.522; p = 0.042) and OS (HR: 2.671; p = 0.001); ICI was a predictor of improved PFS (HR: 0.571; p = 0.071) and longer OS (HR: 0.401; p = 0.062). In the Non-ICI cohort, multivariate analyses revealed PTV > 700cc (HR: 1.630; p = 0.047) and SUVmax > 13.75 (HR: 1.859; p = 0.012) were predictors of reduced PFS; PTV > 700cc (HR: 1.958; p = 0.017), SUVmax > 13.75 (HR: 2.405; p = 0.002) and total lung V20 > 30 (HR: 3.357; p < 0.05) were predictors of longer OS. Conclusions: Regardless of ICI, patients receiving multimodal therapy after 2018 demonstrated improved survival compared to patients treated earlier. Both PTV > 700cc and ICI were predictive for PFS and OS in the entire cohort.

e20589 Background: Durvalumab maintenance treatment after completion of concurrent chemoradiotherapy (CRT) in patients with inoperable stage III NSCLC is the international standard. In this propensity-matched analysis, we prospectively evaluated the role of concurrent/sequential versus sequential immune checkpoint inhibition. Methods: Between 10/1/2016 and 12/31/2020, 39 NSCLC patients in stage IIIA/B/C were analyzed. 11 (28%) patients received concurrent/sequential PD-1 inhibition (nivolumab) and 28 (72%) patients received sequential PD-L1 inhibition (durvalumab) up to one year after the end of CRT. A 1:2 propensity score matching (PSM) using age, gender, T category and histology was performed to reduce selection bias and address for confounding factors (n = 33, 11 patients receiving nivolumab (SIM-cohort), 22 patients receiving durvalumab (SEQ-cohort). Treatment-related adverse events were assessed weekly during the CRT and at 6 weeks, 3,6,9, and 12 months after the end of CRT. Results: The median follow-up time of the overall cohort, SIM-I cohort, and SEQ-I cohort was 27.6, 33.3, and 26.5 months after CRT, respectively. For the entire cohort median survival (OS) was not reached; median progression-free survival (PFS) achieved 26.3 months. In the SIM-cohort, median PFS was 22.8 months and median OS was not reached. In the SEQ-cohort, neither median PFS nor OS was reached. PFS at 12/24 months was 82/44% in the SIM-cohort and 57/57% in the SEQ-cohort (p = 0.714), respectively. In the SIM-cohort, 18.2% of patients showed grade III pneumonitis; in the SEQ-cohort 13.6% (p = 0.735). Grade 4 and 5 toxicities were not observed. Conclusions: Both concurrent/sequential and sequential immune checkpoint inhibition shows a favorable side effect profile and promising survival in terated patients. Concurrent immunotherapy did not result in an improved outcome (PFS, OS) compared to sequential approach. However, our propensity-matched analysis found that concurrent immunotherapy was associated with a non-significant moderate increase in grade III pneumonitis.

9035 Background: In the Phase 3 POSEIDON study in 1L mNSCLC, adding T to D+CT resulted in statistically significant improvements in PFS and OS vs CT. No new safety signals were identified and treatment discontinuations due to treatment-related AEs (TRAEs) were similar for the T+D+CT and D+CT arms (15.5% and 14.1%). Here we present details of AEs and their management. Methods: 1013 pts with EGFR/ ALK wild-type mNSCLC were randomized 1:1:1 to 1L T+D+CT, D+CT or CT. Safety was assessed in all treated pts. Results: 330, 334 and 333 pts received T+D+CT, D+CT and CT; 78%, 82% and 74% received at least 4 cycles of platinum-based CT. The most common grade 3/4 TRAEs were hematologic (anemia in 17%, 15% and 20% of pts in the T+D+CT, D+CT and CT arms and neutropenia in 16%, 13% and 12%) and most were managed using standard approaches per local practice; 22%, 18% and 16% of pts received colony stimulating factors and 22%, 21% and 26% received blood transfusions. All grade immune-mediated AEs (imAEs) occurred in 34%, 19% and 5% of pts in the T+D+CT, D+CT and CT arms; a higher incidence of diarrhea/colitis, dermatitis/rash and endocrinopathies was seen with the addition of T to D+CT (Table). Grade 3/4 imAEs occurred in 10%, 7% and 2% of pts in the T+D+CT, D+CT and CT arms, and serious imAEs in 10%, 6% and 1%; imAEs led to discontinuation of any study treatment in 6%, 4% and 0.6%, and led to death in 0.6%, 0.3% and 0%. Most imAEs were low grade and manageable with systemic corticosteroids (received by 26%, 13% and 4% of pts in the T+D+CT, D+CT and CT arms) or endocrine therapy (12%, 8% and 1%). Median time from first dose to onset of imAEs (TTO) was generally > 60 days and the majority of non-endocrine imAEs resolved (Table). Conclusions: In POSEIDON, the safety profile of all regimens was manageable per standard guidelines and in line with the known profiles of D, T+D and CT; the most common grade 3/4 TRAEs were those typically associated with CT. As expected, more imAEs occurred with T+D+CT than D+CT, but the incidence of grade 3 or 4 imAEs, imAE-related deaths and treatment discontinuations due to imAEs was generally similar in the IO arms. T+D did not compromise the ability to administer planned CT. Clinical trial information: NCT03164616. [Table: see text]

e20570 Background: We compared pattern of failure in patients treated with chemoradiotherapy (CRT) with concurrent and/or sequential Programmed Cell Death 1 (PD-1) or Ligand 1 (PD-L1) immune checkpoint inhibition (IO, immuno-oncology therapy) and CRT alone for inoperable stage III NSCLC. Methods: Prospective data of thirty nine consecutive patients who completed CRT-IO with sequential durvalumab (72%, 28 patients) or concurrent and sequential nivolumab (28%, 11 patients) and a sensitive propensity score matched (PSM adjusted for patients age, gender, T- and N-status, PTV, histology) cohort of 39 patients treated with CRT alone were analyzed. First site of failure was compared between the CRT-IO and the CRT alone subgroup. Results: All patients were treated with conventionally fractionated thoracic irradiation to a total dose of at least 60Gy (range: 60-66Gy), all patients received either sequential or simultaneous chemotherapy while 95% (74 patients; CRT-IO: 38/39; CRT alone: 36/39) received two cycles of concurrent platinum-based chemotherapy. Median follow-up for the entire cohort was 33.3 (range: 1.5-102.9) months; median overall survival (OS) was 34.9 (95%CI: 10.7-59.1) months (CRT-IO: not reached; CRT alone: 24.4, p = 0.003); median progression-free survival (PFS) was 13.6 (95% CI: 10.5-6.7) months (CRT-IO: 26.3; CRT alone: 8.3; p < 0.001). At the time of evaluation 21 (53.8%) vs. 7 (17.9%) patients of the CRT-IO vs. CRT alone subgroup were progression free and alive (p = 0.003); 4 (10.3%) vs. 3 (7.7%) had brain metastases as first site of failure; 7 (17.9%) vs. 6 (15.4%) had ≤ 3 extracranial metastasis and 3 (7.7%) vs. 4 (10.3%) had multi-organ progression. Local-regional recurrence (LRR) as first site of failure was significantly less frequent in patients treated with CRT-IO vs. CRT alone, namely 3 (7.7%) vs. 12 (30.8%) patients (p = 0.001); median time to LRR was not reached vs. 15.0 (95%CI: 0.9-33.7) months. Conclusions: Pattern of failure differ significantly in patients treated with CRT-IO vs. CRT alone; CRT-IO patients are significantly less likely to develop a LRR. No differences in the prevalence of brain metastases as first site of failure could be detected.

e20558 Background: PET-derived metabolic-tumor-volume (MTV) has shown to be an independent prognosticator in non-small cell lung cancer (NSCLC) patients treated with chemoradiotherapy (CRT). We analysed the prognostic value of residual MTV after completion of thoracic irradiation (TRT) in inoperable stage III NSCLC patients treated with CRT with and without immune check-point inhibition (ICI). Methods: Fifty-six inoperable stage III NSCLC patients (16 female, median age: 65 years) underwent 18F-FDG PET/CT at the same institution before and after completion of CRT. MTV was delineated on 18F-FDG PET/CT using a standard threshold (hepatic SUVmean + 2 x standard-deviation). Patients were divided in volumetric subgroups using median split dichotomization (residual MTV ≤4.0 ml & > 4.0 ml). Residual MTV, clinical features and ICI maintenance (RCT-IO; 21/56 (37.5%) patients) were correlated with clinical outcome (progression-free survival (PFS), local PFS (LPFS), metastasis-free survival (MFS), and overall survival (OS). Results: Median follow-up was 52.0 months. 52 (93%) patients were treated with CRT, 12 (21%) patients with CRT followed by durvalumab, and 9 (16%) patients treated with CRT plus nivolumab (concurrent and sequential). In the entire cohort, smaller residual MTV was associated with longer PFS (median 29.3 vs. 10.5 months, p = 0.015); PFS in patients treated with CRT and ICI was also significantly longer compared to the CRT-only subgroup (median 29.3 vs. 11.2 months, p = 0.010). However, residual MTV was predictive for longer PFS in CRT-only (median 33.5 vs. 8.6 months, p = 0.001), but not in the CRT-ICI patients (p = 0.909). Analogously, patients with smaller MTV had a longer LPFS (median 49.9 vs. 16.3 months, p = 0.002); CRT-ICI patients showed a significantly longer LPFS compared to CRT-only patients (median not reached vs. 16.9 months, p = 0.016). Residual MTV remained a significant prognosticator for LPFS in the CRT-only (median 49.9 vs. 10.1 months, p = 0.01), but not in CRT-ICI patients (p = 0.291). Again, smaller residual MTV remained a significant prognosticator for OS in the CRT-only subgroup (median 63.0 vs. 16.3 months, p = 0.004), but not in CRT-ICI patients (p = 0.720). Even in patients with larger residual MTV, the application of ICI significantly improved OS compared to CRT-only subgroup (median not reached vs. 22.9 months, p = 0.004). Conclusions: Smaller residual MTV is associated with superior clinical outcome in inoperable stage III NSCLC, especially in patients undergoing CRT-only. In contrast, in patients undergoing concurrent or sequential consolidation clinical outcome was independent of residual MTV. Hence, even patients with extensive residual MTV might significantly profit from ICI consolidation.

e20503 Background: Acute lymphocytopenia is associated with poor survival in solid cancers treated with multimodal therapy. A prospective analysis of peripheral blood mononuclear cells (PBMCs) during multimodal treatment in inoperable stage III NSCLC patients was performed to assess a correlation of T-lymphocytes changes with 6-months progression-free survival rates (PFS6M). Methods: Twenty patients at median age of 65.5 years (range 33-77), 85% male, 55% with adenocarcinoma and 40% with squamous cell carcinoma, were prospectively enrolled in this study. Eighteen (90%) patients received platinum-based concurrent chemo-radiotherapy (cCRT); seven (35%) patients additional concurrent and/or sequential immune check-point inhibition (four patients nivolumab and three durvalumab); patients treated with nivolumab received induction chemotherapy. Thoracic irradiation (TRT) was applied in all patients with median cumulative dose in equivalent 2Gy fractions (EQD2) of 64Gy (range: 52-65Gy). Peripheral blood was collected 5-10 days before treatment begin (A1), on the last day of TRT (RTend), and during follow-up. Samples were analyzed using polychromatic flow cytometry. Results are reported for three time-points: A1, RTend, and 6 months after TRT (C3) or the last sample available before that time-point. Results: From A1 to RTend, 16 (80%) patients experienced severe T-cell (CD3+, CD3+CD4+, CD3+CD8+) depletion, including 3 (15%) patients who received two doses of concurrent nivolumab. T-lymphocyte nadir was independent of the absolute numbers of PBMCs before treatment begin. In two patients, T-cell count remained stable, and increased in two other patients. No correlation of dynamic changes from A1 to RTend with PFS6M was observed. From RTend to C3, T-lymphocytes recovered in 11 (55%) patients; in 6 (30%) T-cell count further decreased or remained at very low levels. For total CD3 T-cells, CD3+CD4+ and CD3+CD8+ subsets, progressive disease in the first six months after TRT was associated with a decrease of median values (P = 0.03 for total CD3+ and CD3+CD4+, P = 0.08 for CD3+CD8+ T-cells). In contrast, an increase of all medians was associated with PFS6M (P = 0.007 for total CD3+, P = 0.002 for CD3+CD4+, P = 0.06 for CD3+CD8+ T-cells). Conclusions: There is a significant difference between patients with regards to T-lymphocytes recovery after the end of TRT, which is predictive for PFS6M, with poor median recovery observed in patients with early progress.

9012 Background: In the VISION study, tepotinib in METex14 skipping NSCLC pts (Cohort A) had robust and durable clinical activity. Serial LBx samples were collected for biomarker analyses, presented herein. Methods: LBx samples taken at baseline (BL), Week 6, 12, & end of treatment (EOT) were analyzed using Guardant360® CDx (73 genes). Investigator (INV)-assessed clinical outcome was evaluated per BL biomarker profiles and by molecular response (MR; defined as > 75% depletion from BL in METex14 variant allele frequency [VAF] ctDNA confirmed in 2 consecutive samples) or molecular progression (MP; defined as VAF increase > 0 from BL). Acquired resistance was investigated in EOT samples, following progression per INV. Results: LBx pts (n = 99) had a median age of 72 yrs (range 49–88), 53% were male, 44% never smokers, 85% had adenocarcinoma. INV ORR was 53% (95% CI 42, 63); ORR in 1L (n = 44) was 59% (43, 74) & ≥2L (n = 55) was 47% (33, 61). 94 pts had BL biomarker profiles; these were similar in 1L and ≥2L pts, except EGFR amp: 1/43 1L [2%] vs 8/51 ≥2L [16%]. Outcomes were not impacted by location/type of METex14 alteration. 1 pt with concomitant MET M1250T mutation had a PFS of 17.3 months. A trend towards better efficacy was seen in pts with concomitant MET amp (6 responses in 8 pts). Response to tepotinib occurred both in pts with wt or mutant TP53; however, there was a trend for longer mDOR in pts with wt TP53 (18.3 [95% CI 9.7, ne] vs 7.1 [4.7, 10.9] months) and mPFS (9.5 [6.7, 19.7] vs 5.1 [2.8, 6.9] months). Concomitant oncogenic mutations were rare, with no responses in 3 pts with KRAS, NRAS alterations and 3 responses in 5 pts with PI3K/AKT alterations. 65 pts had 2 consecutive on-treatment samples: 46 (71%) had confirmed MR, 5 (8%) had confirmed MP, 14 (22%) had no change in VAF or lacked confirmation. MR was associated with clinical response and MP was associated with no response/short PFS (Table). 52 pts with progression had EOT LBx samples. Emerging MET resistance mutations (Y1230H/C & D1228H/N) occurred in 7 (13%) pts, all responders and 5/7 had PFS > 10 months. Analyses on non-MET-driven resistance mechanisms will be presented. Conclusions: LBx biomarker analysis from the largest on-treatment data set for a MET inhibitor in METex14 skipping NSCLC, showed that ctDNA depletion in METex14 VAF is associated with improved clinical response in pts treated with tepotinib. This suggests serial LBx could help us to monitor response/non-response, understand resistance, and guide trials that test escalation/de-escalation strategies to improve outcomes and maximize QOL. Clinical trial information: NCT02864992. [Table: see text]

9068 Background: In the Phase 3, randomized, open-label CASPIAN study, first-line durvalumab (D) added to etoposide plus either cisplatin or carboplatin (EP) significantly improved OS vs EP alone (HR 0.73 [95% CI 0.59–0.91]; p = 0.0047) in pts with ES-SCLC at the planned interim analysis. Here we describe treatment patterns and outcomes for pts according to brain metastases. Methods: Treatment-naïve pts (WHO PS 0/1) with ES-SCLC received 4 cycles of D 1500 mg + EP q3w followed by maintenance D 1500 mg q4w until disease progression (PD) or up to 6 cycles of EP q3w and optional prophylactic cranial irradiation (PCI; investigator’s discretion). Pts with either asymptomatic or treated and stable brain metastases were eligible. Brain imaging was suggested for pts with suspected brain metastases, but was not mandated at screening or during treatment. The primary endpoint was OS. Analysis of OS and PFS in pt subgroups with and without brain metastases was prespecified. Other analyses in these subgroups were post hoc. Data cutoff: Mar 11, 2019. Results: At baseline, 28 (10.4%) of 268 pts in the D + EP arm and 27 (10.0%) of 269 pts in the EP arm had known brain metastases; of these, only 3 pts (~11% of those with baseline brain metastases) in each arm received radiotherapy (RT) to the brain prior to study entry. D + EP consistently improved OS vs EP in pts with or without known brain metastases at baseline (HR 0.69 [95% CI 0.35–1.31] and 0.74 [0.59–0.93], respectively); PFS was also consistently improved with D + EP regardless of the presence or not of baseline brain metastases (HR 0.73 [0.42–1.29] and 0.78 [0.64–0.95]). Among pts without known brain metastases at baseline, similar proportions developed new brain metastases at first PD in the D + EP (20/240; 8.3%) and EP arms (23/242; 9.5%), despite 19 (7.9%) pts in the EP arm having received PCI. Overall, 48 of 268 (17.9%) and 49 of 269 (18.2%) pts in the D + EP and EP arms received RT to the brain subsequent to study treatment; rates remained similar across the D + EP and EP arms regardless of baseline brain metastases (11 of 28 [39.3%] and 11 of 27 [40.7%] pts with known baseline brain metastases, compared to 37 of 240 [15.4%] and 38 of 242 [15.7%] pts without known baseline brain metastases). Conclusions: In CASPIAN, OS and PFS outcomes were improved with D + EP vs EP regardless of baseline brain metastases, consistent with the ITT analyses. Rates of new brain metastases at first PD were similar between arms, although PCI was permitted only in the control arm. Rates of subsequent RT to the brain were also similar in both arms. Clinical trial information: NCT03043872.

9002 Background: CASPIAN is an open-label, Phase 3 study of durvalumab (D) ± tremelimumab (T) + etoposide and either cisplatin or carboplatin (EP) for pts with 1L ES-SCLC. At the planned interim analysis (data cutoff Mar 11, 2019; 63% maturity), D + EP demonstrated a statistically significant improvement in OS compared with EP alone (HR 0.73 [95% CI 0.59–0.91]; p=0.0047). Here we present a planned updated analysis of OS for D + EP vs EP and the first results for D + T + EP vs EP. Methods: Treatment-naïve pts with ES-SCLC (WHO PS 0/1) were randomized 1:1:1 to D 1500 mg + EP q3w, D 1500 mg + T 75 mg + EP q3w, or EP q3w. In the IO arms, pts received 4 cycles of EP + D ± T, followed by maintenance D 1500 mg q4w until disease progression. Pts received one additional dose of T 75 mg post EP in the D + T + EP arm. In the EP arm, pts received up to 6 cycles of EP and optional PCI (investigator’s discretion). The two primary endpoints were OS for D + EP vs EP and for D + T + EP vs EP. Results: 268, 268 and 269 pts were randomized to D + EP, D + T + EP and EP, respectively; baseline characteristics were generally well balanced across arms. As of Jan 27, 2020, the median follow-up was 25.1 mo, 82% maturity. D + EP continued to demonstrate improvement in OS vs EP, with a HR of 0.75 (95% CI 0.62–0.91; nominal p=0.0032); median OS 12.9 vs 10.5 mo, respectively. 22.2% of pts were alive at 2 y with D + EP vs 14.4% of pts with EP. D + T + EP numerically improved OS vs EP, however this did not reach statistical significance per the prespecified statistical plan: HR 0.82 (95% CI 0.68–1.00; p=0.0451 [p≤0.0418 required for stat sig]); the median OS was 10.4 mo and 23.4% of pts were alive at 2 y. Secondary endpoints of PFS and ORR remained improved with D + EP vs EP and will be presented. Confirmed investigator-assessed ORR was similar for D + T + EP vs EP (58.4% vs 58.0%). Median PFS was similar for D + T + EP vs EP (4.9 mo vs 5.4 mo), but the 12-mo PFS rate was numerically higher (16.9% vs 5.3%); PFS HR 0.84 (95% CI 0.70–1.01). In the D + EP, D + T + EP and EP arms, respectively, incidences of all-cause AEs of Grade 3/4 were 62.3%, 70.3% and 62.8%; AEs leading to discontinuation 10.2%, 21.4% and 9.4%; and AEs leading to death 4.9%, 10.2% and 5.6%. Conclusions: The addition of durvalumab to EP continued to demonstrate improvement in OS compared with a robust control arm, further supporting this regimen as a new standard of care for 1L ES-SCLC offering the flexibility of platinum choice. No additional benefit was observed when T was combined with D + EP in this pt population. Safety findings in all arms remained consistent with the known safety profiles of all agents. Clinical trial information: NCT03043872.

9556 Background: Preliminary tepotinib data showed durable activity in pts with NSCLC with METex14 skipping prospectively identified by liquid (L+) or tissue (T+) biopsy. Having met target enrollment of ≥60 L+ pts & ≥60 T+ pts, we report primary data. Methods: VISION Cohort A enrolled pts with advanced EGFR/ALK wt, METex14 skipping NSCLC (asymptomatic brain metastases [BM] allowed), who received oral tepotinib 500 mg QD. On-study treatment decisions were based on investigator assessment (INV) of response. Primary endpoint was objective response rate (ORR) by independent review committee (IRC) analyzed in 3 primary ITT sets: L+ and/or T+, L+, T+. 2ary endpoints included ORR by INV, duration of response (DOR), disease control rate (DCR), PFS, OS, & safety. Preplanned analyses were performed in pts with BM at baseline (BL). BL/on-treatment ctDNA plasma samples (L+) were analyzed using a 73-gene NGS panel (Guardant360). Deep molecular responses (MR), defined as > 75% depletion of METex14, were compared with objective responses (OR). Results: By data cut-off (1 Oct 19) 151 pts received tepotinib (safety set); 99 L+/T+, 66 L+, 60 T+ pts comprised the 3 ITT sets with ≥6-month [m] follow-up. Across treatment lines (n = 44 1L, n = 55 ≥2L), primary ORR & mPFS [95% CI] in 99 L+/T+ pts were 43% [34–54] & 8.6 m [6.9–11.0] by IRC and 56% [45–66] & 9.5 m [6.7–13.5] by INV. ORR was similar in L+ or T+ pts (table) or in T+L− pts (n = 25): 40% [21–61] by IRC and 48% [28–69] by INV. Only 2 pts were T−L+. Outcomes were also comparable in pts with BM (n = 11): IRC ORR 55% [23–83] & mPFS 10.9 m [8.0–ne]. 34/51 pts (67%) with matched BL/on-treatment L+ samples had deep MR strongly associated with clinical response: 32/34 pts (94%) with MR had disease control (INV), including 29/34 pts (85%) with OR; 2/34 pts had progressive disease. Further biomarker data will be presented. Grade ≥3 treatment-related adverse events (TRAEs) were reported by 37/151 pts (25%). 13 pts (9%) discontinued due to TRAEs. Conclusions: Tepotinib is a promising targeted therapy with durable clinical activity and manageable toxicity in pts with METex14 skipping NSCLC L+ or T+, including pts with BM. High ORR & DCR in pts with ctDNA molecular responses support that MET inhibition in METex14+ tumor cells can lead to clinical benefit. Clinical trial information: NCT02864992 . [Table: see text]

9016 Background: MYSTIC, an open-label, Ph3 trial of first-line D (anti-PD-L1) ± T (anti-CTLA-4) vs platinum-based CT, showed an improvement in OS with D vs CT in pts with tumor cell PD-L1 expression ≥25% (PD-L1 TC ≥25%; HR 0.76 [97.54% CI 0.56–1.02], p = 0.036). Exploratory analyses showed bTMB was a predictive biomarker for OS with D±T vs CT. We report further exploratory analyses of OS according to PD-L1 and bTMB. Methods: Immunotherapy/CT-naïve pts with mNSCLC were randomized (1:1:1) to D, D+T or CT. bTMB levels (mut/Mb) were evaluated with the GuardantOMNI platform (Guardant Health), and PD-L1 TC expression with the VENTANA PD-L1 (SP263) IHC assay. Results: D improved OS vs CT in pts with PD-L1 TC ≥25% across bTMB levels (PD-L1 TC ≥25%/bTMB≥20 HR 0.79 [95% CI 0.45, 1.39]; PD-L1 TC ≥25%/bTMB < 20 HR 0.64 [95% CI 0.45, 0.90]). In contrast, D+T improved OS vs CT in pts with bTMB≥20 across different PD-L1 TC expression levels (Table; PD-L1 TC ≥25%/bTMB≥20 HR 0.44 [95% CI 0.23, 0.84]; PD-L1 TC < 1%/bTMB≥20 HR 0.42 [95% CI 0.17, 0.97]). Additional cutoffs and outcomes in subgroups defined by both biomarkers will be presented. Conclusions: These exploratory analyses from MYSTIC support PD-L1 TC expression as an appropriate predictive biomarker for OS with D vs CT, while suggesting bTMB as a predictive biomarker for OS with D+T in mNSCLC. These biomarkers appear to be independent and both may be important for mNSCLC treatment decisions. Interpretation of these data may be limited by small sample sizes; further investigations are warranted. Clinical trial information: NCT02453282. [Table: see text]

9048 Background: MYSTIC, an open-label, Phase 3 trial of first-line D (anti-PD-L1) ± T (anti-CTLA-4) vs platinum CT in mNSCLC, showed an improvement in overall survival (OS) with D vs CT in pts with tumor cell PD-L1 expression ≥25% (TC ≥25% [primary analysis population]; D vs CT, HR 0.76 [97.54% CI 0.56–1.02], p = 0.036; D+T vs CT, HR 0.85 [98.77% CI 0.61–1.17], p = 0.202). Here we summarize PROs from MYSTIC. Methods: Immunotherapy/CT-naïve mNSCLC pts were randomized (1:1:1) to D, D+T, or CT. Symptoms, function, and global health status/quality of life (QoL) were assessed using the EORTC QLQ-C30 v3 questionnaire and its lung cancer module, QLQ-LC13. A change in score from baseline ≥10 points was predefined as clinically meaningful (CM). Mean changes from baseline (over 12 mos) for prespecified symptoms were analyzed using a mixed model for repeated measures (MMRM). Time from randomization to the first CM deterioration (TTD) was analyzed. Results: Among pts with PD-L1 TC ≥25% (n = 488), there were no differences between arms in symptoms, function, or global health status/QoL at baseline. Compliance with completing the questionnaires was ≥60% to wk 120 in the D±T arms, and to wk 40 (C30) and wk 44 (LC13) in the CT arm. MMRM analysis showed significant between-arm differences in changes from baseline in favor of D for fatigue (difference vs CT −9.5) and appetite loss (−11.9; CM), and D+T for fatigue (−11.7; CM). Significantly longer TTD (median, mos) was seen with D and D+T vs CT for appetite loss (12.8 and 5.6 vs 4.5), constipation (14.6 and 9.0 vs 5.5), nausea/vomiting (16.7 and 9.7 vs 4.5), and dyspnea (10.6 and 7.4 vs 5.6); D vs CT for diarrhea (16.3 vs 9.0), insomnia (9.3 vs 6.2), and hemoptysis (not reached vs 10.3); and D+T vs CT for fatigue (5.6 vs 2.0). Significantly longer TTD (median, mos) was also seen with D and D+T vs CT for function (cognitive [9.1 and 6.6 vs 5.2], physical [9.0 and 7.4 vs 4.2], role [D vs CT only; 7.3 vs 3.7], social [12.9 and 5.4 vs 5.2]), and global health status/QoL (5.9 and 6.8 vs 5.5). Conclusions: Pts with PD-L1 TC ≥25% treated with D±T had a reduced symptom burden over time and longer TTD for symptoms, function, and global health status/QoL compared to pts receiving CT. Clinical trial information: NCT02453282.

9005 Background: MET exon 14 skipping ( METex14) mutations - reported in 3~4% of NSCLC patients (pts) - are activating, sensitive to MET inhibition and can be conveniently detected using liquid biopsy (LBx). We report data from an ongoing single-arm phase II study of tepotinib, a highly selective MET inhibitor, in NSCLC pts with METex14 mutations identified by LBx or tumor biopsy (TBx) (NCT02864992). Methods: Pts with advanced WT EGFR/ALK NSCLC, prospectively enrolled via either LBx (≥60 pts) or TBx (≥60 pts, overlap anticipated) central RNA-based METex14 mutation testing, receive tepotinib 500 mg QD until progression, intolerable toxicity or withdrawal. Primary endpoint: objective response rate (ORR) by independent review (IRC). Secondary endpoints: ORR by investigator assessment (INV) and safety. Results: To date, 85 pts have been enrolled (55 LBx pts and 52 TBx pts). At data cut-off (16 Oct 2018), in 35 evaluable LBx pts (≥2 post-baseline assessments or discontinuation for any reason), ORR was 51.4% by IRC and 63.9% by INV. In 41 evaluable TBx pts, ORR was 41.5% by IRC and 58.5% by INV. Median duration of response (mDoR) and ORR by line of treatment are shown in the table. Any grade treatment-related adverse events (TRAEs) reported by ≥10% of 69 pts evaluable for safety were peripheral edema (47.8%), diarrhea (18.8%), nausea (15.9%), asthenia (10.1%). No TRAEs were grade 4 or led to death. TRAEs led to permanent discontinuation in 2 (2.9%) pts (1 ILD, 1 diarrhea & nausea). Conclusions: Tepotinib has promising activity with a long DoR across treatment lines in NSCLC pts with METex14 mutations detected by LBx or TBx. The safety profile was favorable. Recruitment is ongoing. Clinical trial information: NCT02864992. [Table: see text]

7504 Background: Combining EGFR kinase inhibition (E) with an anti-VEGF strategy (B) showed promising activity (RR 20%; PFS 6.2 months) in recurrent NS-NSCLC (J Clin Oncol (2005) 23: 2544). To asse...

e18096 Background: Only sparse data are known to characterize lung cancer patients with previous malignancies. The aim of this study was to identify risk profiles for patient subgroups that could finally lead to adapted screening procedures. Methods: All patients with small cell lung cancer (SCLC) or non-SCLC (NSCLC) that were treated in our clinic between 2004 and 2006 were screened for further malignancies in their history. Data of identified patients were collected after obtaining an ethical approval. NSCLC patients without a previously treated malignancy (PrevMal) and updated follow-up served as a control group. Results: In a preliminary analysis, 436 lung cancer patients with a PrevMal were identified (Table). The previous tumors included the following: 69 breast cancers, 67 prostate cancers, 35 kidney cancers, 32 colorectal cancers, and 27 bladder cancers. 2,241 patients served as controls (con). Median age (67 vs. 64.6 years) and sex distribution (PrevMal 67% male, 33% female; Con 71% male, 29% fem...