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The phase 3 RATIONALE-303 trial (NCT03358875) investigated the efficacy and safety of tislelizumab versus docetaxel in pretreated patients with advanced NSCLC. Here, we report the efficacy and safety results and describe the exploratory biomarker analyses.A total of 805 patients aged more than or equal to 18 years with locally advanced or metastatic squamous or nonsquamous NSCLC were randomized 2:1 to intravenous tislelizumab 200 mg or docetaxel 75 mg/mAt the prespecified interim analysis (August 10, 2020), the co-primary end point of OS in the ITT population was met, with a statistically significant and clinically meaningful improvement in OS with tislelizumab versus docetaxel (median 17.2 versus 11.9 mo, respectively; hazard ratio [HR] = 0.64, p0.0001). At the final analysis (July 15, 2021), the other co-primary end point of OS in the PD-L1 tumor cell greater than or equal to 25% population was further met (median 19.3 versus 11.5 mo, respectively; HR = 0.53, p0.0001), and OS continued to improve in the ITT population (median 16.9 versus 11.9 mo, respectively, HR = 0.66). Exploratory biomarker analyses revealed the potential association of NOTCH1-4 mutations with improved tislelizumab efficacy for both OS and progression-free survival, whereas tissue tumor mutation burden correlated with progression-free survival benefit, but not OS benefit. No new safety signals were identified.Tislelizumab was found to have a significantly improved and long-term clinical benefit in OS versus docetaxel in pretreated patients with advanced NSCLC, regardless of PD-L1 expression.

First-line cemiplimab (anti-programmed cell death-1 (PD-1)) monotherapy has previously shown significant improvement in overall survival (OS) and progression-free survival (PFS) versus chemotherapy in patients with advanced non-small cell lung cancer (aNSCLC) and PD-ligand 1 (PD-L1) expression ≥50%. EMPOWER-Lung 3 (NCT03409614), a double-blind, placebo-controlled, phase 3 study, examined cemiplimab plus platinum-doublet chemotherapy as first-line treatment for aNSCLC, irrespective of PD-L1 expression or histology. In this study, 466 patients with stage III/IV aNSCLC without EGFR, ALK or ROS1 genomic tumor aberrations were randomized (2:1) to receive cemiplimab 350 mg (n = 312) or placebo (n = 154) every 3 weeks for up to 108 weeks in combination with four cycles of platinum-doublet chemotherapy (followed by pemetrexed maintenance as indicated). In total, 57.1% (266/466 patients) had non-squamous NSCLC, and 85.2% (397/466 patients) had stage IV disease. The primary endpoint was OS. The trial was stopped early per recommendation of the independent data monitoring committee, based on meeting preset OS efficacy criteria: median OS was 21.9 months (95% confidence interval (CI), 15.5–not evaluable) with cemiplimab plus chemotherapy versus 13.0 months (95% CI, 11.9–16.1) with placebo plus chemotherapy (hazard ratio (HR) = 0.71; 95% CI, 0.53–0.93; P = 0.014). Grade ≥3 adverse events occurred with cemiplimab plus chemotherapy (43.6%, 136/312 patients) and placebo plus chemotherapy (31.4%, 48/153 patients). Cemiplimab is only the second anti-PD-1/PD-L1 agent to show efficacy in aNSCLC as both monotherapy and in combination with chemotherapy for both squamous and non-squamous histologies.

Programmed cell death ligand 1 inhibitors combined with chemotherapy has changed the approach to first-line treatment in patients with extensive-stage small cell lung cancer (SCLC). It remained unknown whether adding a programmed cell death 1 (PD-1) inhibitor to chemotherapy provided similar or better benefits in patients with extensive-stage SCLC, which would add evidence on the efficacy of checkpoint inhibitors in the treatment of extensive-stage SCLC.To evaluate the efficacy and adverse event profile of the PD-1 inhibitor serplulimab plus chemotherapy compared with placebo plus chemotherapy as first-line treatment in patients with extensive-stage SCLC.This international, double-blind, phase 3 randomized clinical trial (ASTRUM-005) enrolled patients at 114 hospital sites in 6 countries between September 12, 2019, and April 27, 2021. Of 894 patients who were screened, 585 with extensive-stage SCLC who had not previously received systemic therapy were randomized. Patients were followed up through October 22, 2021.Patients were randomized 2:1 to receive either 4.5 mg/kg of serplulimab (n = 389) or placebo (n = 196) intravenously every 3 weeks. All patients received intravenous carboplatin and etoposide every 3 weeks for up to 12 weeks.The primary outcome was overall survival (prespecified significance threshold at the interim analysis, 2-sided P .012). There were 13 secondary outcomes, including progression-free survival and adverse events.Among the 585 patients who were randomized (mean age, 61.1 [SD, 8.67] years; 104 [17.8%] women), 246 (42.1%) completed the trial and 465 (79.5%) discontinued study treatment. All patients received study treatment and were included in the primary analyses. As of the data cutoff (October 22, 2021) for this interim analysis, the median duration of follow-up was 12.3 months (range, 0.2-24.8 months). The median overall survival was significantly longer in the serplulimab group (15.4 months [95% CI, 13.3 months-not evaluable]) than in the placebo group (10.9 months [95% CI, 10.0-14.3 months]) (hazard ratio, 0.63 [95% CI, 0.49-0.82]; P .001). The median progression-free survival (assessed by an independent radiology review committee) also was longer in the serplulimab group (5.7 months [95% CI, 5.5-6.9 months]) than in the placebo group (4.3 months [95% CI, 4.2-4.5 months]) (hazard ratio, 0.48 [95% CI, 0.38-0.59]). Treatment-related adverse events that were grade 3 or higher occurred in 129 patients (33.2%) in the serplulimab group and in 54 patients (27.6%) in the placebo group.Among patients with previously untreated extensive-stage SCLC, serplulimab plus chemotherapy significantly improved overall survival compared with chemotherapy alone, supporting the use of serplulimab plus chemotherapy as the first-line treatment for this patient population.ClinicalTrials.gov Identifier: NCT04063163.

Background: SB3 (trastuzumab-dttb) is a biosimilar approved globally based on its similarity with reference trastuzumab (TRZ) demonstrated by thorough comparability exercises in analytical, biological, and clinical studies. In a randomized, double-blind, multicenter Phase 3 study of 875 patients with HER2-positive early or locally advanced breast cancer in the neoadjuvant setting, equivalent efficacy, similar safety, pharmacokinetics, and immunogenicity between SB3 and TRZ were shown. However, when quality attributes of TRZ were examined, downward drifts in antibody-dependent cell-mediated cytotoxicity activities (ADCC) were observed in the TRZ lots with expiry dates ranging from Aug 2018 to Dec 2019. Some of these lots of the reference product were found to be used in the Phase 3 study. After completing the Phase 3 study, patients from select countries were included in a follow-up observational study to monitor cardiac safety and survival. Here, we report the final survival results, including post-hoc subgroup analysis based on ADCC status, at a median follow-up of 68 months. Methods: During the follow-up observational study, the protocol was amended to include additional patients who originally were enrolled in the Phase 3 study but had not been followed in the observational study, in order to collect a larger sample of survival data. For these additional patients, medical records from the last assessment in the Phase 3 study through the date of enrollment in the follow-up study were collected retrospectively. As post-hoc analysis, patients in the TRZ arm were stratified into two subgroups: patients who received during neoadjuvant treatment at least one vial of TRZ with downward drift in ADCC as “Drifted TRZ”, and the others as “Non-drifted TRZ”. Event-free survival (EFS) and overall survival (OS) were assessed. Results: Of 875 patients randomized in the Phase 3 study, 538 patients (SB3, N=267; TRZ, N=271) were enrolled in the follow-up observational study: 367 patients were initially enrolled in the follow-up study, and 171 patients were additionally enrolled following the protocol amendment. The median follow-up duration was 68 months from randomization in the Phase 3 study. 54 events (20.2%) in the SB3 arm, and 67 events (24.7%) in the TRZ arm were reported (HR 0.84 [0.58, 1.20], p=0.335). 22 deaths (8.2%) and 38 deaths (14%) were reported in SB3 and TRZ arms, respectively (HR 0.61 [0.36, 1.05], p=0.073). In post-hoc analysis, of 271 patients in TRZ arm, 107 patients were grouped as “Non-drifted TRZ”, and 164 patients as “Drifted TRZ”. 19 events (17.8%) in the Non-drifted TRZ group and 48 (29.3%) events in the Drifted TRZ group occurred (HR 2.57 [1.28, 5.14], p=0.008). 9 deaths (8.4%) in the Non-drifted TRZ group and 29 deaths (17.7%) in the Drifted TRZ group were reported (HR 3.87 [1.37, 10.93], p=0.011). No difference was observed between SB3 arm and Non-drifted TRZ group in terms of EFS (HR 1.28 [0.73, 2.22], p=0.391) and OS (HR 0.99 [0.42, 2.31], p=0.975). Conclusions: Comparable long-term efficacy results in EFS and OS were shown at 68 months of follow-up, further supporting biosimilarity of SB3 to the reference product. Currently, these follow-up results represent the longest monitoring data of patients treated with a trastuzumab biosimilar for HER2-positive early or locally advanced breast cancer. Citation Format: Xavier Pivot, Mark D Pegram, Javier Cortes, Diana Lüftner, Gary H Lyman, Giuseppe Curigliano, Igor M Bondarenko, Mikhail Dvorkin, Jin Hee Ahn, Seock-Ah Im, Maria Litwiniuk, Yaroslav V Shparyk, Gwo Fuang Ho, Nikolay V Kislov, Marek Wojtukiewicz, Tomasz Sarosiek, Yee Soo Chae, Jin Seok Ahn, Hyerin Jang, Sujung Kim, Jiwon Lee, Soo Young Lee, Ye Chan Yoon. Final survival analysis of a phase 3 study comparing SB3 (trastuzumab biosimilar) and reference trastuzumab in HER2-positive early or locally advanced breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-13-04.

Background Bevacizumab is an antiangiogenic recombinant humanized monoclonal antibody that inhibits tumor growth. FKB238, a bevacizumab biosimilar, has analytical pharmacokinetic and safety profiles similar to those of bevacizumab. Objective This phase III trial (NCT02810457) compared the efficacy and safety of FKB238 with that of bevacizumab in patients with advanced/recurrent non-squamous non-small-cell lung cancer (non-sq-NSCLC). Methods This global, multicenter, double-blind, parallel, randomized, comparative clinical trial enrolled and randomized patients with advanced/recurrent non-sq-NSCLC to receive intravenous infusions of either FKB238 15 mg/kg or bevacizumab 15 mg/kg. All patients received intravenous infusions of paclitaxel 200 mg/m2 and carboplatin (area under the curve 6.0) immediately prior to investigational products for 4–6 cycles. FKB238 and bevacizumab were administered on day 1 of each 21-day cycle until objective progressive disease by RECIST version 1.1 or other discontinuation criteria were met. The primary efficacy endpoint was overall response rate (ORR), including complete and partial response and based on blinded independent central review assessment. Other efficacy determinations included progression-free survival (PFS), overall survival (OS), and immunogenicity. Adverse events and severity were reported. Results The ORR for the intent-to-treat (ITT) population (N = 731) was 51.6% in the FKB238 arm (N = 364) and 53.7% in the bevacizumab arm (N = 367). The FKB238:bevacizumab ORR ratio (ITT population) was 0.96 (90% confidence interval [CI] 0.86–1.08), and the difference in ORR (per-protocol set) between FKB238 and bevacizumab was − 0.02 (95% CI − 0.09 to 0.06). Both CIs fell within the prespecified equivalence margins. Estimated median PFS was 7.72 and 7.62 months in the FKB238 and bevacizumab arms, respectively (hazard ratio 0.97; 95% CI 0.82–1.16). Treatment-emergent adverse events (TEAEs) were reported for 94.2% and 95.1% of patients in the FKB238 and bevacizumab arms, respectively. Grade 3 or higher TEAEs were reported for 53.6% and 55.5% of patients in the FKB238 and bevacizumab arms, respectively. Serious TEAEs were reported for 25.1% and 26.0% of patients treated with FKB238 and bevacizumab, respectively. Conclusions Efficacy equivalence was demonstrated between the two drugs, and safety profiles were similar. There were no meaningful differences in efficacy and safety between FKB238 or bevacizumab in patients with non-sq-NSCLC. Trial registration number NCT02810457.

Small cell lung cancer (SCLC) is an aggressive form of lung cancer with a 5-year survival rate of less than 7%. In contrast to non–small cell lung cancer, SCLC has long been treated as a homogeneous disease without personalized treatment options. In recent years, the incorporation of immunotherapy into the treatment paradigm has brought moderate benefit to patients with SCLC; however, more effective therapies are urgently needed. In this article, we describe the current treatment standards and emerging therapeutic approaches for the treatment of SCLC. We also discuss promising biomarkers in SCLC and the recently discovered four subtypes of SCLC, each with its unique therapeutic vulnerability. Lastly, we discuss the advances in radiation therapy for the treatment of SCLC.

Background: First-line durvalumab plus etoposide with either cisplatin or carboplatin (platinum–etoposide) showed a significant improvement in overall survival versus platinum–etoposide alone in patients with extensive-stage small-cell lung cancer (ES-SCLC) in the CASPIAN study. Here we report updated results, including the primary analysis for overall survival with durvalumab plus tremelimumab plus platinum–etoposide versus platinum–etoposide alone. Methods: CASPIAN is an ongoing, open-label, sponsor-blind, randomised, controlled phase 3 trial at 209 cancer treatment centres in 23 countries worldwide. Eligible patients were aged 18 years or older (20 years in Japan) and had treatment-naive, histologically or cytologically documented ES-SCLC, with a WHO performance status of 0 or 1. Patients were randomly assigned (1:1:1) in blocks of six, stratified by planned platinum, using an interactive voice-response or web-response system to receive intravenous durvalumab plus tremelimumab plus platinum–etoposide, durvalumab plus platinum–etoposide, or platinum–etoposide alone. In all groups, patients received etoposide 80–100 mg/m2 on days 1–3 of each cycle with investigator's choice of either carboplatin area under the curve 5–6 mg/mL/min or cisplatin 75–80 mg/m2 on day 1 of each cycle. Patients in the platinum–etoposide group received up to six cycles of platinum–etoposide every 3 weeks and optional prophylactic cranial irradiation (investigator's discretion). Patients in the immunotherapy groups received four cycles of platinum–etoposide plus durvalumab 1500 mg with or without tremelimumab 75 mg every 3 weeks followed by maintenance durvalumab 1500 mg every 4 weeks. The two primary endpoints were overall survival for durvalumab plus platinum–etoposide versus platinum–etoposide and for durvalumab plus tremelimumab plus platinum–etoposide versus platinum–etoposide in the intention-to-treat population. Safety was assessed in all patients who received at least one dose of study treatment. This study is registered at ClinicalTrials.gov, NCT03043872. Findings: Between March 27, 2017, and May 29, 2018, 972 patients were screened and 805 were randomly assigned (268 to durvalumab plus tremelimumab plus platinum–etoposide, 268 to durvalumab plus platinum–etoposide, and 269 to platinum–etoposide). As of Jan 27, 2020, the median follow-up was 25·1 months (IQR 22·3–27·9). Durvalumab plus tremelimumab plus platinum–etoposide was not associated with a significant improvement in overall survival versus platinum–etoposide (hazard ratio [HR] 0·82 [95% CI 0·68–1·00]; p=0·045); median overall survival was 10·4 months (95% CI 9·6–12·0) versus 10·5 months (9·3–11·2). Durvalumab plus platinum–etoposide showed sustained improvement in overall survival versus platinum–etoposide (HR 0·75 [95% CI 0·62–0·91]; nominal p=0·0032); median overall survival was 12·9 months (95% CI 11·3–14·7) versus 10·5 months (9·3–11·2). The most common any-cause grade 3 or worse adverse events were neutropenia (85 [32%] of 266 patients in the durvalumab plus tremelimumab plus platinum–etoposide group, 64 [24%] of 265 patients in the durvalumab plus platinum–etoposide group, and 88 [33%] of 266 patients in the platinum–etoposide group) and anaemia (34 [13%], 24 [9%], and 48 [18%]). Any-cause serious adverse events were reported in 121 (45%) patients in the durvalumab plus tremelimumab plus platinum–etoposide group, 85 (32%) in the durvalumab plus platinum–etoposide group, and 97 (36%) in the platinum–etoposide group. Treatment-related deaths occurred in 12 (5%) patients in the durvalumab plus tremelimumab plus platinum–etoposide group (death, febrile neutropenia, and pulmonary embolism [n=2 each]; enterocolitis, general physical health deterioration and multiple organ dysfunction syndrome, pneumonia, pneumonitis and hepatitis, respiratory failure, and sudden death [n=1 each]), six (2%) patients in the durvalumab plus platinum–etoposide group (cardiac arrest, dehydration, hepatotoxicity, interstitial lung disease, pancytopenia, and sepsis [n=1 each]), and two (1%) in the platinum–etoposide group (pancytopenia and thrombocytopenia [n=1 each]). Interpretation: First-line durvalumab plus platinum–etoposide showed sustained overall survival improvement versus platinum–etoposide but the addition of tremelimumab to durvalumab plus platinum–etoposide did not significantly improve outcomes versus platinum–etoposide. These results support the use of durvalumab plus platinum–etoposide as a new standard of care for the first-line treatment of ES-SCLC. Funding: AstraZeneca.

Background In TAGS, an international, double-blind, phase 3 trial, trifluridine/tipiracil significantly improved overall survival and progression-free survival compared with placebo in heavily pretreated metastatic gastric cancer patients. This paper reports pre-specified quality of life (QoL) outcomes for TAGS. Methods Patients were randomized 2:1 to trifluridine/tipiracil (35 mg/m2 twice daily on days 1–5 and 8–12 of each 28-day cycle) plus best supportive care (BSC) or placebo plus BSC. QoL was evaluated at baseline and at each treatment cycle, using the EORTC QLQ-C30 and EORTC QLQ-STO22 questionnaires; results were considered valid for analysis only if ≥ 10% of patients completed the questionnaires. Key QoL outcomes were mean changes from baseline and time to deterioration in QoL. A post hoc analysis assessed the association between QoL and time to deterioration of Eastern Cooperative Oncology Group performance score (ECOG PS) to ≥ 2. Results Of 507 randomized patients, 496 had baseline QoL data available. The analysis cut-off was 6 cycles for trifluridine/tipiracil and 3 cycles for placebo. In both treatment groups, there were no clinically significant deteriorations in the mean QLQ-C30 Global Health Status (GHS) score, or in most subscale scores. In a sensitivity analysis including death and disease progression as events, there was a trend towards trifluridine/tipiracil reducing the risk of deterioration of QoL scores compared with placebo. Deterioration in the GHS score was associated with deterioration in ECOG PS. Conclusion QoL was maintained in TAGS, and there was a trend towards trifluridine/tipiracil reducing the risk of QoL deterioration compared with placebo. Trial registration ClinicalTrials.gov number: NCT02500043

Background: Few prospective studies have compared poly(adenosine diphosphate-ribose) polymerase (PARP) inhibitors to chemotherapy for the treatment of BRCA1-mutated or BRCA2-mutated ovarian carcinoma. We aimed to assess rucaparib versus platinum-based and non-platinum-based chemotherapy in this setting. Methods: In this open-label, randomised, controlled, phase 3 study (ARIEL4), conducted in 64 hospitals and cancer centres across 12 countries (Brazil, Canada, Czech Republic, Hungary, Israel, Italy, Poland, Russia, Spain, Ukraine, the UK, and the USA), we recruited patients aged 18 years and older with BRCA1-mutated or BRCA2-mutated ovarian carcinoma, with an Eastern Cooperative Oncology Group performance status of 0 or 1, and who had received two or more previous chemotherapy regimens. Eligible patients were randomly assigned (2:1), using an interactive response technology and block randomisation (block size of six) and stratified by progression-free interval after the most recent platinum-containing therapy, to oral rucaparib (600 mg twice daily) or chemotherapy (administered per institutional guidelines). Patients assigned to the chemotherapy group with platinum-resistant or partially platinum-sensitive disease were given paclitaxel (starting dose 60–80 mg/m2 on days 1, 8, and 15); those with fully platinum-sensitive disease received platinum-based chemotherapy (single-agent cisplatin or carboplatin, or platinum-doublet chemotherapy). Patients were treated in 21-day or 28-day cycles. The primary endpoint was investigator-assessed progression-free survival, assessed in the efficacy population (all randomly assigned patients with deleterious BRCA1 or BRCA2 mutations without reversion mutations), and then in the intention-to-treat population (all randomly assigned patients). Safety was assessed in all patients who received at least one dose of assigned study treatment. This study is registered with ClinicalTrials.gov, NCT02855944; enrolment is complete, and the study is ongoing. Findings: Between March 1, 2017, and Sept 24, 2020, 930 patients were screened, of whom 349 eligible patients were randomly assigned to rucaparib (n=233) or chemotherapy (n=116). Median age was 58 years (IQR 52–64) and 332 (95%) patients were White. As of data cutoff (Sept 30, 2020), median follow-up was 25·0 months (IQR 13·8–32·5). In the efficacy population (220 patients in the rucaparib group; 105 in the chemotherapy group), median progression-free survival was 7·4 months (95% CI 7·3–9·1) in the rucaparib group versus 5·7 months (5·5–7·3) in the chemotherapy group (hazard ratio [HR] 0·64 [95% CI 0·49–0·84]; p=0·0010). In the intention-to-treat population (233 in the rucaparib group; 116 in the chemotherapy group), median progression-free survival was 7·4 months (95% CI 6·7–7·9) in the rucaparib group versus 5·7 months (5·5–6·7) in the chemotherapy group (HR 0·67 [95% CI 0·52–0·86]; p=0·0017). Most treatment-emergent adverse events were grade 1 or 2. The most common grade 3 or worse treatment-emergent adverse event was anaemia or decreased haemoglobin (in 52 [22%] of 232 patients in the rucaparib group vs six [5%] of 113 in the chemotherapy group). Serious treatment-emergent adverse events occurred in 62 (27%) patients in the rucaparib group versus 13 (12%) in the chemotherapy group; serious adverse events considered related to treatment by the investigator occurred in 32 (14%) patients in the rucaparib group and six (5%) in the chemotherapy group. Three deaths were considered to be potentially related to rucaparib (one due to cardiac disorder, one due to myelodysplastic syndrome, and one with an unconfirmed cause). Interpretation: Results from the ARIEL4 study support rucaparib as an alternative treatment option to chemotherapy for patients with relapsed, BRCA1-mutated or BRCA2-mutated ovarian carcinoma. Funding: Clovis Oncology.

Topotecan is approved as second-line treatment for small cell lung cancer (SCLC). Irinotecan is also frequently used given its more convenient schedule and superior tolerability. Preclinical studies support disialoganglioside (GD2) as an SCLC target and the combination of dinutuximab, an anti-GD2 antibody, plus irinotecan in this setting. We tested dinutuximab/irinotecan versus irinotecan or topotecan as second-line therapy in relapsed/refractory (RR) SCLC.Patients with RR SCLC and Eastern Cooperative Oncology Group performance status 0-1 were randomized 2:2:1 to receive dinutuximab 16-17.5 mg/mA total of 471 patients were randomized to dinutuximab/irinotecan (n = 187), irinotecan (n = 190), or topotecan (n = 94). Age, sex, performance status, prior therapies, and metastatic disease sites were similar between groups. Survival and response rates were not improved for patients receiving dinutuximab/irinotecan versus those receiving irinotecan or topotecan (median OS 6.9 vs 7.0 vs 7.4 months [p = 0.3132]; median PFS 3.5 vs 3.0 vs 3.4 months [p = 0.3482]; ORR confirmed 17.1% vs 18.9% vs 20.2% [p = 0.8043]; and CBR 67.4% vs 58.9% vs 68.1% [p = 0.0989]), respectively. Grade 3/4 adverse events (≥5% receiving dinutuximab/irinotecan) included neutropenia, anemia, diarrhea, and asthenia.Dinutuximab/irinotecan treatment did not result in improved OS in RR SCLC versus irinotecan alone. Irinotecan administered every 21 days demonstrated comparable activity to topotecan administered daily × 5 every 21 days.gov Identifier. NCT03098030.

Background: Avelumab, a human IgG1 anti–PD-L1 monoclonal antibody, has shown antitumor activity and a manageable safety profile in several tumor types. Talazoparib, an orally available PARP inhibitor, is approved for the treatment of patients with deleterious or suspected deleterious germline BRCA1/2-mutated HER2− locally advanced (LA) or metastatic (M) breast cancer (BC). Preclinical data suggest that PARP inhibitors may have synergistic activity when administered in combination with immune checkpoint inhibitors. We report results from patients with LA/MBC enrolled in the phase 1b/2, multicohort JAVELIN PARP Medley study (NCT03330405). Methods: In phase 1b (cohort 1), patients with advanced solid tumors who had received ≥1 prior standard of care chemotherapy (CT) regimen were treated with avelumab 800 mg IV every 2 weeks (Q2W) in combination with talazoparib 1.0 mg orally once daily (QD) (dose de-escalation to 0.75 or 0.5 mg permitted following toxicity). In 2 phase 2 cohorts, eligible patients had either LA/M triple-negative BC (TNBC, cohort 2A) or LA/M hormone receptor positive (HR+), HER2−, DNA damage repair defect-positive BC (cohort 2B). Patients in cohort 2A had received 0 to 2 prior CT regimens (no progression on prior platinum-based CT) and patients in cohort 2B had received prior standard of care hormone therapy in either the adjuvant and/or LA/M setting followed by 0 to 2 prior CT regimens (no progression on prior platinum-based CT). The primary endpoint for phase 1b was first-cycle dose-limiting toxicities (DLTs) and for phase 2 was objective response (investigator assessed per RECIST v1.1). Adverse events (AEs) were characterized using National Cancer Institute Common Terminology Criteria for AEs v4.03. Results: By the data cutoff on December 24, 2018, 34 patients had been treated in cohorts 1 and 2. Twelve patients with advanced solid tumors were treated in cohort 1 (including 2 patients with TNBC); 3 patients (25.0%) had a first-cycle DLT: grade 3 neutropenia, (n=1) and grade 3 thrombocytopenia, (n=2). Best overall response (BOR) was partial response (PR) in 1 patient, stable disease (SD) in 3, progressive disease (PD) in 6, and non-complete response/non-PD in 1 patient with metastatic castration-resistant prostate cancer and non-measurable disease at baseline; 1 patient was not evaluable for response. Both patients with TNBC had a BOR of SD and remained on treatment for ≥9 months. Objective response rate in this pre-treated and heterogenous population was 8.3% (95% CI, 0.2, 38.5). Based on the phase 1b data, the recommended phase 2 dose was avelumab 800 mg Q2W and talazoparib 1 mg QD. By data cutoff, 22 patients had been treated in cohorts 2A (n=19) and 2B (n=3); median age was 56 and 50 years, respectively. In cohort 2A, 12 patients were evaluable for disease assessment; BOR was PR in 1, SD in 6, and PD in 5. All 3 patients in cohort 2B were non-evaluable for response at data cutoff. Treatment-related AEs (TRAEs) of any grade occurred in 11 patients (91.7%) in cohort 1, and 18 (94.7%) patients in cohort 2A. In cohort 2A, the most common TRAEs were anemia (57.9%), nausea (26.3%), fatigue (21.1%) and thrombocytopenia (21.1%); 9 patients (47.4%) had grade ≥3 TRAEs. There were no treatment-related deaths. Safety data from cohort 2B are not reported owing to low patient numbers. Observed pharmacokinetic (PK) data for avelumab 800 mg Q2W were similar to simulated data derived from a population PK model developed using 10 mg/kg dosing. Conclusions: Avelumab 800 mg Q2W administered in combination with talazoparib 1 mg QD in patients with advanced solid tumors, showed preliminary antitumor activity and a manageable safety profile, which was comparable to the safety profiles of the single agents. The study is ongoing; updated safety and efficacy data, and biomarker data will be presented. Citation Format: Timothy A Yap, Panagiotis Konstantinopoulos, Melinda L. Telli, Smita Saraykar, J Thaddeus Beck, Matthew D. Galsky, Jame Abraham, David R. Wise, Mustafa Khasraw, Gabor Rubovszky, Mikhail Dvorkin, Anil A Joy, Mateusz Opyrchal, Daria Stypinski, Colombe Chappey, Ross Stewart, Rossano Cesari, Anita Scheuber, Aditya Bardia. JAVELIN PARP Medley, a phase 1b/2 study of avelumab plus talazoparib: Results from advanced breast cancer cohorts [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P1-19-03.

Background: Most patients with small-cell lung cancer (SCLC) have extensive-stage disease at presentation, and prognosis remains poor. Recently, immunotherapy has demonstrated clinical activity in extensive-stage SCLC (ES-SCLC). The CASPIAN trial assessed durvalumab, with or without tremelimumab, in combination with etoposide plus either cisplatin or carboplatin (platinum–etoposide) in treatment-naive patients with ES-SCLC. Methods: This randomised, open-label, phase 3 trial was done at 209 sites across 23 countries. Eligible patients were adults with untreated ES-SCLC, with WHO performance status 0 or 1 and measurable disease as per Response Evaluation Criteria in Solid Tumors, version 1.1. Patients were randomly assigned (in a 1:1:1 ratio) to durvalumab plus platinum–etoposide; durvalumab plus tremelimumab plus platinum–etoposide; or platinum–etoposide alone. All drugs were administered intravenously. Platinum–etoposide consisted of etoposide 80–100 mg/m2 on days 1–3 of each cycle with investigator's choice of either carboplatin area under the curve 5–6 mg/mL per min or cisplatin 75–80 mg/m2 (administered on day 1 of each cycle). Patients received up to four cycles of platinum–etoposide plus durvalumab 1500 mg with or without tremelimumab 75 mg every 3 weeks followed by maintenance durvalumab 1500 mg every 4 weeks in the immunotherapy groups and up to six cycles of platinum–etoposide every 3 weeks plus prophylactic cranial irradiation (investigator's discretion) in the platinum–etoposide group. The primary endpoint was overall survival in the intention-to-treat population. We report results for the durvalumab plus platinum–etoposide group versus the platinum–etoposide group from a planned interim analysis. Safety was assessed in all patients who received at least one dose of their assigned study treatment. This study is registered at ClinicalTrials.gov, NCT03043872, and is ongoing. Findings: Patients were enrolled between March 27, 2017, and May 29, 2018. 268 patients were allocated to the durvalumab plus platinum–etoposide group and 269 to the platinum–etoposide group. Durvalumab plus platinum–etoposide was associated with a significant improvement in overall survival, with a hazard ratio of 0·73 (95% CI 0·59–0·91; p=0·0047]); median overall survival was 13·0 months (95% CI 11·5–14·8) in the durvalumab plus platinum–etoposide group versus 10·3 months (9·3–11·2) in the platinum–etoposide group, with 34% (26·9–41·0) versus 25% (18·4–31·6) of patients alive at 18 months. Any-cause adverse events of grade 3 or 4 occurred in 163 (62%) of 265 treated patients in the durvalumab plus platinum–etoposide group and 166 (62%) of 266 in the platinum–etoposide group; adverse events leading to death occurred in 13 (5%) and 15 (6%) patients. Interpretation: First-line durvalumab plus platinum–etoposide significantly improved overall survival in patients with ES-SCLC versus a clinically relevant control group. Safety findings were consistent with the known safety profiles of all drugs received. Funding: AstraZeneca.

Background: At a predefined interim analysis (IA), RATIONALE-303 (NCT03358875) demonstrated improved overall survival (OS) for TIS vs D in the intent-to-treat (ITT), with a manageable safety profile. Disease characteristics, standard of care and treatment/prognosis differ between histologic types of NSCLC. Here, we report on the non-sq population. Methods: 805 patients with histologically confirmed, advanced NSCLC with progressive disease during or after ≥ 1 platinum (Pt)-containing chemotherapy regimen were randomized (2:1) to TIS 200 mg or D 75 mg/m2 every 3 weeks until disease progression, intolerable toxicity, or withdrawal. Histology (sq vs non-sq) was a randomization stratification factor. Dual primary endpoints were OS in the ITT and PD-L1 ≥ 25% populations. A prespecified IA was conducted after ~426 deaths (76% of planned events). Efficacy and safety were assessed in 435 randomized patients with non-sq histology. Results: Baseline characteristics of non-sq patients were balanced between treatment arms and similar to the ITT population. As of August 10, 2020, at median follow-up of 20 and 17 months (mo), respectively, median (95% CI) OS was longer with TIS (18.6 mo [15.41, 23.16]) vs D (13.8 mo [9.43, 17.94]) in the non-sq ITT population, and objective response rate (ORR) and duration of response (DoR) were also improved for TIS vs D (Table). 95.5% (TIS) and 97.9% (D) of patients had ≥ 1 treatment-emergent adverse event (TEAE) and 39.0% (TIS) and 70.9% (D) of patients had ≥ Grade 3 TEAEs. The most common TEAEs were anemia, aspartate aminotransferase increased and alanine aminotransferase increased (TIS arm), and alopecia, anemia and neutrophil count decreased (D arm). Conclusions: TIS prolonged OS, consistent with the overall ITT population, with a favorable safety profile in patients with advanced non-sq NSCLC who progressed after a Pt-containing regimen. Table Efficacy* TIS (n=287) D (n=148) Median OS, mo (95% CI) 18.6 (15.41, 23.16) 13.8 (9.43, 17.94) OS HR (95% CI)† 0.71 (0.538, 0.929) P=0.0064‡,§ Median PFS, mo (95% CI) 2.5 (2.14, 4.01) 3.6 (2.17, 4.14) PFS HR (95% CI)† 0.84 (0.660, 1.062) P=0.0686‡,§ ORR, n (%) 60 (20.9) 14 (9.5) Median DoR, mo (95% CI) 11.7 (6.80, 14.65) 6.2 (2.10, 7.16) Safety** TIS (n=287) D (n=141) TEAEs ≥ 15% of patients in either arm, n (%) All grades ≥ Grade 3 All grades ≥ Grade 3 Anemia 76 (26.5) 11 (3.8) 56 (39.7) 6 (4.3) AST increased 64 (22.3) 5 (1.7) 18 (12.8) 0 (0.0) ALT increased 63 (22.0) 4 (1.4) 24 (17.0) 0 (0.0) Cough 59 (20.6) 4 (1.4) 25 (17.7) 0 (0.0) Weight decreased 44 (15.3) 2 (0.7) 13 (9.2) 0 (0.0) Decreased appetite 41 (14.3) 3 (1.0) 26 (18.4) 0 (0.0) Hypoalbuminemia 37 (12.9) 0 (0.0) 23 (16.3) 0 (0.0) Nausea 37 (12.9) 0 (0.0) 22 (15.6) 0 (0.0) Constipation 31 (10.8) 0 (0.0) 22 (15.6) 0 (0.0) Asthenia 29 (10.1) 1 (0.3) 29 (20.6) 8 (5.7) Neutrophil count decreased 8 (2.8) 1 (0.3) 53 (37.6) 36 (25.5) White blood cell count decreased 8 (2.8) 0 (0.0) 42 (29.8) 26 (18.4) Neutropenia 7 (2.4) 3 (1.0) 44 (31.2) 38 (27.0) Leukopenia 6 (2.1) 0 (0.0) 38 (27.0) 22 (15.6) Alopecia 0 (0.0) 0 (0.0) 70 (49.6) 2 (1.4) *Efficacy analysis set - non-sq patients; †Stratified; ‡One-sided stratified log-rank test; §Descriptive P-value; **Safety analysis set - non-squamous patients ALT, alanine aminotransferase; AST, aspartate aminotransferase; CI; confidence interval; DoR, duration of response; HR, hazard ratio; mo, months; NE, not evaluable; ORR, objective response rate; PFS, progression-free survival; TEAE, treatment-emergent adverse event Data cut-off: August 10, 2020 Citation Format: Ying Cheng, Dingzhi Huang, Zhiyong Ma, Yun Fan, Jie Wang, Xinmin Yu, Mikhail Dvorkin, Gareth Rivalland, Yiyuan Ma, Yan Wang, Yan Ma, Caicun Zhou. Tislelizumab (TIS) versus docetaxel (D) in patients with previously treated advanced non-squamous (non-sq) non-small-cell lung cancer (NSCLC): Subanalysis from the RATIONALE-303 phase 3 randomized clinical study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT553.

Background: Lorlatinib improved progression-free survival (PFS) and demonstrated intracranial (IC) activity in patients (pts) with untreated advanced ALK+ NSCLC in the interim analysis of the randomized, Phase 3, CROWN study of lorlatinib vs crizotinib. We report updated 36-month follow-up data. Methods: 296 pts with previously untreated advanced ALK+ NSCLC were randomized 1:1 to oral lorlatinib (100 mg QD; n=149) or crizotinib (250 mg BID; n=147), stratified by presence of CNS metastases (mets) and ethnicity. Primary endpoint: PFS by blinded independent central review (BICR). Secondary endpoints included overall survival, PFS by investigator, and objective response (OR), IC-OR, IC time to progression (IC-TTP), duration of response (DR), IC-DR (all by BICR), and safety. Results: At data cutoff (Sep 20, 2021), median duration of follow-up for PFS was 36.7 months for lorlatinib and 29.3 months for crizotinib. Median PFS by BICR was NR (95% CI, NR-NR) for lorlatinib and 9.3 months (95% CI, 7.6-11.1) for crizotinib (HR, 0.27; 95% CI, 0.18-0.39). PFS by investigator results were similar (Table). For pts with brain mets at baseline (n=37 lorlatinib/n=39 crizotinib), the HR for IC-TTP for lorlatinib vs crizotinib was 0.10 (95% CI, 0.04-0.27), and for pts without brain mets (n=112/n=108) was 0.02 (95% CI, 0.002-0.14). OR, IC-OR, DR, and IC-DR were all improved with lorlatinib vs crizotinib (Table). All-cause grade 3-4 adverse events (AEs) and AEs leading to treatment discontinuation were reported in 76% and 7% of pts with lorlatinib and 57% and 10% of pts with crizotinib, respectively. No new safety signals emerged. Conclusions: These updated long-term data from CROWN confirm the efficacy of lorlatinib over crizotinib in pts with treatment-naïve ALK+ NSCLC, with no new safety signals detected, and support the use of lorlatinib in pts with untreated ALK+ NSCLC with and without brain mets. Summary of other efficacy resultsa Clinical trial information: NCT03052608 Funding: Pfizer Inc. ITT population Lorlatinib(n=149) Crizotinib(n=147) % alive without progression at:12 mo (95% CI) 78 (70–84) 38 (29–47) 24 68 (60–75) 22 (14–30) 36 64 (55–71) 19 (12–27) Median PFS by investigator, mo (95% CI) NR (NR–NR) 9.1 (7.4–10.9) HR (95% CI) 0.19 (0.13–0.27) Confirmed OR, n (%) [95% CI] 115 (77) [70–84] 86 (59) [50–67] Median DR,b mo (95% CI) NR (NR–NR) 9.6 (9.0–12.9) Patients with measurable or nonmeasurable brain metastases at baseline (n=37) (n=39) Median PFS, mo (95% CI) NR (18.2–NR) 7.2 (3.7–9.2) HR (95% CI) 0.21 (0.10–0.44) Confirmed IC-OR, n (%) [95% CI] 24 (65) [48–80] 7 (18) [8–34] Complete response, n (%) 22 (60) 5 (13) Median IC-DR,b mo (95% CI) NR (NR–NR) 9.4 (6.0–11.1) Patients without brain metastases at baseline (n=112) (n=108) Median PFS, mo (95% CI) NR (NR–NR) 11.0 (9.0–14.6) HR (95% CI) 0.29 (0.19–0.44) aBy blinded independent central review unless stated otherwise. bIn patients with a confirmed complete or partial response. CI, confidence interval; DR, duration of response; HR, hazard ratio; ITT, intention- to-treat; NR, not reached; IC, intracranial; OR, objective response; PFS, progression-free survival. Citation Format: Benjamin Solomon, Todd Bauer, Tony Mok, Geoffrey Liu, Julien Mazieres, Filippo de Marinis, Yasushi Goto, Dong-Wan Kim, Yi-Long Wu, Mikhail Dvorkin, Jacek Jassem, Froylán López-López, Ross Soo, Anna Polli, Elisa Dall'O, Laura Iadeluca, Francesca Toffalorio, Enriqueta Felip. Updated efficacy and safety from the phase 3 CROWN study of first-line lorlatinib vs crizotinib in advanced anaplastic lymphoma kinase (ALK)-positive non-small cell lung cancer (NSCLC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT223.

PURPOSE The role of maintenance therapy for gastric (GC) or gastroesophageal junction cancer (GEJC) is unclear. We investigated avelumab (anti–programmed death ligand-1 [PD-L1]) maintenance after first-line induction chemotherapy for GC/GEJC. PATIENTS AND METHODS JAVELIN Gastric 100 was a global, open-label, phase III trial. Eligible patients had untreated, unresectable, human epidermal growth factor receptor 2–negative, locally advanced or metastatic GC or GEJC. Patients without progressive disease after 12 weeks of first-line chemotherapy with oxaliplatin plus a fluoropyrimidine were randomly assigned 1:1 to avelumab 10 mg/kg every 2 weeks or continued chemotherapy, stratified by region (Asia v non-Asia). The primary end point was overall survival (OS) after induction chemotherapy in all randomly assigned patients or the PD-L1–positive randomly assigned population (≥ 1% of tumor cells; 73-10 assay). RESULTS A total of 805 patients received induction; 499 were randomly assigned to avelumab (n = 249) or continued chemotherapy (n = 250). Median OS was 10.4 months (95% CI, 9.1 to 12.0 months) versus 10.9 months (95% CI, 9.6 to 12.4 months) and 24-month OS rate was 22.1% versus 15.5% with avelumab versus chemotherapy, respectively (hazard ratio [HR], 0.91; 95% CI, 0.74 to 1.11; P = .1779). In the PD-L1–positive population (n = 54), the HR for OS was 1.13 (95% CI, 0.57 to 2.23; P = .6352). In an exploratory analysis of the PD-L1–positive population, defined as combined positive score ≥ 1 (22C3 assay; n = 137), median OS was 14.9 months (95% CI, 8.7 to 17.3 months) with avelumab versus 11.6 months (95% CI, 8.4 to 12.6 months) with chemotherapy (unstratified HR, 0.72; 95% CI, 0.49 to 1.05). With avelumab and chemotherapy, treatment-related adverse events (TRAEs) occurred in 149 (61.3%) and 184 (77.3%) patients, including grade ≥ 3 TRAEs in 31 (12.8%) and 78 (32.8%) patients, respectively. CONCLUSION JAVELIN Gastric 100 did not demonstrate superior OS with avelumab maintenance versus continued chemotherapy in patients with advanced GC or GEJC overall or in a prespecified PD-L1–positive population.

OZGUROGLU, MUSTAFA/0000-0002-8417-8628 WOS:000579504300008 PubMed ID: 32961445 Objectives: In the phase III CASPIAN study, first-line durvalumab plus etoposide in combination with either cisplatin or carboplatin (EP) significantly improved overall survival (primary endpoint) versus EP alone in patients with extensive-stage small-cell lung cancer (ES-SCLC) at the interim analysis. Here we report patient-reported outcomes (PROs). Materials and methods: Treatment-naive patients with ES-SCLC received 4 cycles of durvalumab plus EP every 3 weeks followed by maintenance durvalumab every 4 weeks until progression, or up to 6 cycles of EP every 3 weeks. PROs, assessed with the European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire-Core 30 (QLQ-C30) version 3 and its lung cancer module, the Quality of Life Questionnaire-Lung Cancer 13 (QLQ-LC13), were prespecified secondary endpoints. Changes from baseline to disease progression or 12 months in prespecified key disease-related symptoms (cough, dyspnea, chest pain, fatigue, appetite loss) were analyzed with a mixed model for repeated measures. Time to deterioration (TTD) of symptoms, functioning, and global health status/quality of life (QoL) from randomization was analyzed. Results: In the durvalumab plus EP and EP arms, 261 and 260 patients were PRO-evaluable. Patients in both arms experienced numerically reduced symptom burden over 12 months or until progression for key symptoms. For the improvements from baseline in appetite loss, the between-arm difference was statistically significant, favoring durvalumab plus EP (difference, 4.5; 99% CI: 9.04, 0.04; nominal p = 0.009). Patients experienced longer TTD with durvalumab plus EP versus EP for all symptoms (hazard ratio [95% CI] for key symptoms: cough 0.78 [0.600-1.026]; dyspnea 0.79 [0.625-1.006]; chest pain 0.76 [0.575-0.996]; fatigue 0.82 [0.653-1.027]; appetite loss 0.70 [0.542-0.899]), functioning, and global health status/QoL. Conclusion: Addition of durvalumab to first-line EP maintained QoL and delayed worsening of patient-reported symptoms, functioning, and global health status/QoL compared with EP. AstraZenecaAstraZeneca The study was funded by AstraZeneca.

Objectives: Prospective studies comparing poly(adenosine diphosphate-ribose) polymerase (PARP) inhibitors with standard-of-care (SOC) chemotherapy (CT) in patients (pts) with relapsed ovarian cancer (OC) are currently limited. ARIEL4 (NCT02855944) is a phase III, randomized, open-label, international, multicenter study of the efficacy and safety of rucaparib vs SOC CT as treatment for PARP-inhibitor naive pts with relapsed high-grade epithelial ovarian, fallopian tube or primary peritoneal cancer, who had a deleterious BRCA1/2 (BRCA) mutation and had received ≥2 prior CT regimens. Methods: Pts were randomized 2:1 to oral rucaparib 600 mg twice daily or SOC CT and stratified based on progression-free interval (≥1 to Results: A total of 233 pts were randomized to rucaparib and 116 to CT (visit cutoff Sep 30, 2020); 179 (51.3%) had platinum-resistant, 96 (27.5%) had partially platinum-sensitive, and 74 (21.2%) had fully platinum-sensitive disease. A total of 23 pts (6.6%) with BRCA reversion mutations and 1 pt without a BRCA mutation were excluded from the efficacy population. Median PFS was significantly longer with rucaparib vs CT in both the efficacy and ITT populations (Table). In an exploratory analysis of pts with BRCA reversion mutations, median PFS was shorter with rucaparib (n=13) vs CT (n=10); 2.9 vs 5.5 months, hazard ratio 2.769 (95% CI, 0.989–7.755). ORR was not significantly different between the rucaparib and CT arms in both populations (Table). Adverse events were consistent with the known safety profiles of rucaparib and CT. Download : Download high-res image (119KB) Download : Download full-size image Conclusions: Patients with BRCA-mutated advanced, relapsed OC who received rucaparib had a significant improvement in PFS vs SOC CT. No new safety signals were identified. This is the first prospective report from a randomized trial demonstrating that the presence of a BRCA reversion mutation predicts for primary resistance to rucaparib.

Results From RATIONALE 303: A Global Phase 3 Study of Tislelizumab (TIS) vs Docetaxel (TAX) as Second- or Third-Line Therapy for Patients With Locally Advanced or Metastatic NSCLC Background: Anti-PD-1/L1 therapies have improved OS by 2-4 mo vs TAX in patients (pts) with advanced NSCLC who progressed after platinum regimens. TIS is an anti-PD-1 antibody engineered to minimize FcγR binding on macrophages, a mechanism of T-cell clearance and potential anti-PD-1 resistance. Methods: RATIONALE 303 (BGB-A317-303; NCT03358875) compared efficacy and safety of TIS vs TAX as 2 or 3L therapy for pts with advanced NSCLC. Patients without oncogenic driver mutation who failed at least 1 prior systemic therapy including a platinum regimen were randomized 2:1 to receive TIS 200 mg IV Q3W (Arm A) or TAX 75 mg/m2 IV Q3W (Arm B). Dual primary endpoints were OS in the ITT analysis set and OS in the PD-L1 high (≥25% TC) analysis set. A prespecified interim analysis (IA) was conducted after ≈426 deaths (76% of planned events); in the IA, formal OS superiority testing was conducted only in the ITT. The IA results are presented. Results: Overall, 805 pts were randomized (n=535, TIS; n=270, TAX); demographics were generally balanced between arms. With a 19-mo median follow-up (441 OS events), median OSITT was significantly longer in Arm A vs B (17.2 vs 11.9 mo; HR=0.64 [95% CI: 0.53, 0.78]; P Conclusions: RATIONALE 303 demonstrated that, as 2 or 3L therapy in pts with advanced NSCLC, TIS was tolerable and prolonged OS by 5-7 mo with improved PFS and ORR vs TAX regardless of histology or PD-L1 expression. ITT Analysis Set (N=805)Arm A Tislelizumab (n=535)Arm B Docetaxel (n=270)EfficacyMedian OS, mo17.211.9OS difference, mo5.3HR (95% CI)a0.64 (0.53, 0.78)P-valuea,b Citation Format: Caicun Zhou, Dingzhi Huang, Xinmin Yu, Yunpeng Liu, Yun Fan, Yongqian Shu, Zhiyong Ma, Ziping Wang, Ying Cheng, Jie Wang, Sheng Hu, Zhihua Liu, Mikhail Dvorkin, Elena Poddubskaya, Umut Disel, Andrey Akopov, Yiyuan Ma, Yan Wang, Zhenyu Pan, Cunjing Yu, Gareth Rivalland. Results from RATIONALE 303: A global phase 3 study of tislelizumab (TIS) vs docetaxel (TAX) as second- or third-line therapy for patients with locally advanced or metastatic NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT039.

3109 Background: A subset of gastric cancers exhibits platinum sensitivity and genomic instability that is characteristic of homologous recombination deficiency (HRD). Cells with HRD are sensitive to poly (ADP-ribose) polymerase (PARP) inhibition. PARP inhibitor maintenance therapy following platinum-based chemotherapy has been a successful treatment strategy in pts with ovarian cancer. Pamiparib is an orally administered selective PARP protein 1 and 2 (PARP1/2) inhibitor that has shown potent DNA-PARP trapping activity and crosses the blood brain barrier in preclinical studies. In early phase clinical studies (NCT02361723; NCT03333915), pamiparib showed an acceptable safety profile and promising antitumor activity. PARALLEL 303 compared the efficacy and safety of pamiparib vs placebo as maintenance therapy in pts with inoperable locally advanced or metastatic gastric cancer that responded to platinum-based 1L chemotherapy. Methods: The primary endpoint of this double-blind, randomized, global phase 2 study (NCT03427814) was progression-free survival (PFS) as determined by the investigator per RECIST Version 1.1. Key secondary endpoints included time to subsequent treatment, objective response rate, duration of response, time to response, overall survival (OS) and safety. At the time of this analysis, OS data were immature due to the short duration of study. Data presented here will focus on PFS and safety. Results: 136 pts were randomized 1:1 to receive pamiparib 60 mg orally (PO) twice daily (BID) (n=71) or placebo PO BID (n=65) in 28-day cycles. The median PFS was longer with pamiparib vs placebo, but did not reach statistical significance (3.7 months; 95% CI, 1.94–5.26 vs 2.1 months; 95% CI, 1.87–3.75 months); hazard ratio 0.799 (95% CI, 0.534–1.193; P=0.1428). Treatment-emergent adverse events (TEAEs) of ≥ Grade 3 were experienced by 29 pts (40.8%) in the pamiparib arm, and 20 pts (30.8%) in the placebo arm. The most common TEAEs of ≥ Grade 3 were blood and lymphatic system disorders in the pamiparib arm, and gastrointestinal disorders in the placebo arm. TEAEs leading to treatment discontinuation were: 8 pts (11.3%) in the pamiparib arm and 2 pts (3.1%) in the placebo arm. TEAEs leading to death were: 2 pts (2.8%; 1 pneumonia, 1 unexplained) in the pamiparib arm, and 2 pts (3.1%; 1 hepatic rupture, 1 sepsis) in the placebo arm. Conclusions: Although pamiparib did not meet statistical significance for superiority vs placebo for its primary endpoint, it was generally well tolerated with few treatment discontinuations due to TEAEs. No new safety signals were identified with pamiparib, and its safety profile was consistent with that of other PARP inhibitors. Clinical trial information: NCT03427814.

5517 Background: In ARIEL4 (NCT02855944), rucaparib significantly improved the primary endpoint of progression-free survival (PFS) vs chemotherapy (CT) in patients with advanced, relapsed ovarian carcinoma (OC) harboring a deleterious BRCA1/2 (BRCA) mutation (median PFS 7.4 [95% CI 7.3–9.1] vs 5.7 [5.5–7.3] months; hazard ratio (HR) 0.64 [95% CI 0.49–0.84]; P=0.001). This prespecified exploratory analysis investigated the effect of platinum sensitivity on the efficacy of rucaparib vs CT in ARIEL4. Methods: Patients were randomized 2:1 to oral rucaparib 600 mg twice daily or CT and stratified based on progression-free interval (≥1 to 2; patients with fully platinum-sensitive disease received investigator’s choice of platinum-based CT (single-agent carboplatin or cisplatin, or platinum doublet). Patients could crossover from CT to rucaparib following radiologic disease progression. Efficacy endpoints were explored in patients with a confirmed BRCA mutation (patients with a reversion mutation were excluded), based on the randomization strata of platinum sensitivity. Results: The visit cutoff date was September 30, 2020. PFS and objective response rates (ORR) per RECIST v1.1 for rucaparib vs CT across subgroups are presented in the Table. The most common treatment-emergent adverse events in the rucaparib group were anemia/decreased hemoglobin (platinum-resistant patients: rucaparib 47% vs CT 40%; partially platinum-sensitive patients: 63% vs 27%; fully platinum-sensitive patients: 58% vs 20%) and nausea (52% vs 21%; 51% vs 23%; 60% vs 68%). In the intent-to-treat population, 74/116 (64%) patients in the CT group crossed over to receive rucaparib: 39/59 (66%) with platinum-resistant, 25/31 (81%) with partially platinum-sensitive, and 10/26 (38%) with fully platinum-sensitive disease. Conclusions: Results from this exploratory subgroup analysis suggest that rucaparib is a reasonable treatment option for heavily pretreated patients across all platinum sensitivity subgroups. Safety was consistent with prior rucaparib studies. Clinical trial information: NCT02855944. [Table: see text]

9017 Background: Although SCLC is highly responsive to initial therapy, most pts relapse < 1 y. Topotecan (T) and irinotecan (I) are used in 2LT of SCLC; however, treatment response is low: ≤10-25% and median survival is ~4-5 months. Preclinical studies support GD2 as an SCLC target. This study evaluated the combination of D+I vs. I alone or T alone in 2LT of SCLC pts. Methods: Pts with RR SCLC, Eastern Cooperative Oncology Group 0-1, were randomized 2:2:1 to receive D 16-17.5 mg/m2 intravenously (IV) plus I 350 mg/m2 IV (Day 1 q21d), I 350 mg/m2 IV (Day 1 q21d), or T 1.5 mg/m2 IV (Days 1-5 q21d). Randomization was stratified by duration of response to prior platinum therapy. Primary endpoint was overall survival (OS) in pts treated with D+I vs. I alone and was analyzed using stratified log-rank test and COX regression. Secondary endpoints included progression-free survival (PFS), objective response rate (ORR), and clinical benefit rate, ORR + stable disease (CBR). Safety was assessed. Results: 471 pts were randomized to D+I (n = 187), I (n = 190), or T (n = 94). Baseline characteristics were balanced (24.2% women; mean ± SD age 61.6 ± 8.7 y). Median OS was similar in pts receiving D+I (6.9 [3.5,10.9] months) vs. I alone (7 [3.6,13.1] months) (HR [95% CI]: 1.12 [0.9,1.4]; P = 0.3132) or T alone (7.4 [3.8,12.8] months) (HR [95% CI]: 1.05 [0.8,1.37]; P = 0.7233). Median PFS was similar in pts receiving D+I (3.5 [1.5,6.2] months) vs. I (3 [1.4,5.7] months) or T (3.4 [1.6, 6.1] months) alone. ORR was similar in pts receiving D+I (17.1%) vs. I (18.9%) or T (20.1%) alone. CBR was similar in pts receiving D+I (67.4%) vs. I (58.9%) or T (68.1%) alone. Grade 3 or higher adverse events were experienced by 77% D+I, 69.5% I, and 86.4% T pts. Conclusions: Treatment with D+I was not superior to established 2LT for RR SCLC. Exploratory analyses are ongoing to evaluate GD2 expression in circulating tumor cells, select protein biomarkers, and any correlative impact on observed response. Clinical trial information: NCT03098030.

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.

578 Background: SB3 was approved in the US and EU as a biosimilar of reference trastuzumab (TRZ). Here, we report 4-year cardiac safety and survival outcomes. Methods: After completing neoadjuvant-adjuvant therapy in patients with HER2 positive early breast cancer, patients from selected countries participated in a 5-year follow-up study of a phase III trial (Pivot et al. Eur J Cancer 2019). The aim was to observe long-term cardiac safety and survival. EFS and OS were analyzed in subgroups by ADCC status within TRZ in ad-hoc analyses. Results: Of 875 patients randomized in the phase III trial, 367 patients (SB3, N=186; TRZ, N=181) were enrolled in the follow-up study. The median follow-up was 53 months. During the follow-up, the incidence of asymptomatic significant left ventricular ejection fraction (LVEF) decrease was low (SB3, n=1; TRZ, n=2), with all patients recovering with LVEF ≥ 50%. No cases of symptomatic congestive heart failure, cardiac death, or other significant cardiac condition were reported. 4-year EFS rates were 83.4% for SB3 and 80.7% for TRZ with a HR of 0.77 [95% CI 0.47, 1.27]. 4-year OS rates were 94.3% for SB3 and 89.6% for TRZ with a HR of 0.53 [95% CI 0.24, 1.16]. From ad-hoc analysis, a difference in EFS and OS was seen between Non-drifted TRZ and Drifted TRZ; Difference between SB3 and Non-drifted TRZ was not statistically significant. Conclusions: In a subset of patients from the phase III trial, comparable long-term cardiac safety and survival at 4-year supports biosimilarity between SB3 and TRZ. Ad-hoc analysis results by ADCC status suggest a possible correlation between ADCC and clinical efficacy. Further follow-up is needed. Clinical trial information: NCT02771795 . [Table: see text]

Avelumab is a human anti-PD-L1 IgG1 monoclonal antibody that has shown antitumor activity in early phase studies in advanced/metastatic gastric/gastroesophageal junction cancer, including as first-line maintenance therapy. Here, we describe the design of JAVELIN Gastric 100 (NCT02625610), an open-label, Phase III trial. A total of 499 patients with locally advanced/metastatic HER2- gastric/gastroesophageal junction cancer adenocarcinoma, who had achieved at least stable disease following 12 weeks of first-line oxaliplatin/fluoropyrimidine chemotherapy, have been randomized 1:1 to receive avelumab maintenance therapy or continue chemotherapy. The primary objective is to demonstrate superior overall survival in all randomized patients or in the PD-L1+ population. Secondary objectives are to demonstrate superiority for progression-free survival and objective response rate, compare quality of life measures, and determine safety.

Purpose This phase III study compared SB3, a trastuzumab (TRZ) biosimilar, with reference TRZ in patients with human epidermal growth factor receptor 2–positive early breast cancer in the neoadjuvant setting ( ClinicalTrials.gov identifier: NCT02149524). Patients and Methods Patients were randomly assigned to receive neoadjuvant SB3 or TRZ for eight cycles concurrently with chemotherapy (four cycles of docetaxel followed by four cycles of fluorouracil, epirubicin, and cyclophosphamide) followed by surgery, and then 10 cycles of adjuvant SB3 or TRZ. The primary objective was comparison of breast pathologic complete response (bpCR) rate in the per-protocol set; equivalence was declared if the 95% CI of the ratio was within 0.785 to 1.546 or the 95% CI of the difference was within ± 13%. Secondary end points included comparisons of total pathologic complete response rate, overall response rate, event-free survival, overall survival, safety, pharmacokinetics, and immunogenicity. Results Eight hundred patients were included in the per-protocol set (SB3, n = 402; TRZ, n = 398). The bpCR rates were 51.7% and 42.0% with SB3 and TRZ, respectively. The adjusted ratio of bpCR was 1.259 (95% CI, 1.085 to 1.460), which was within the predefined equivalence margins. The adjusted difference was 10.70% (95% CI, 4.13% to 17.26%), with the lower limit contained within and the upper limit outside the equivalence margin. The total pathologic complete response rates were 45.8% and 35.8% and the overall response rates were 96.3% and 91.2% with SB3 and TRZ, respectively. Overall, 96.6% and 95.2% of patients experienced one or more adverse event, 10.5% and 10.7% had a serious adverse event, and 0.7% and 0.0% had antidrug antibodies (up to cycle 9) with SB3 and TRZ, respectively. Conclusion Equivalence for efficacy was demonstrated between SB3 and TRZ on the basis of the ratio of bpCR rates. Safety and immunogenicity were comparable.

There are two approaches for de novo protein sequencing: Edman degradation and mass spectrometry (MS). Existing MS-based methods characterize a novel protein by assembling tandem mass spectra of overlapping peptides generated from multiple proteolytic digestions of the protein. Because each tandem mass spectrum covers only a short peptide of the target protein, the key to high coverage protein sequencing is to find spectral pairs from overlapping peptides in order to assemble tandem mass spectra to long ones. However, overlapping regions of peptides may be too short to be confidently identified. High-resolution mass spectrometers have become accessible to many laboratories. These mass spectrometers are capable of analyzing molecules of large mass values, boosting the development of top-down MS. Top-down tandem mass spectra cover whole proteins. However, top-down tandem mass spectra, even combined, rarely provide full ion fragmentation coverage of a protein. We propose an algorithm, TBNovo, for de novo protein sequencing by combining top-down and bottom-up MS. In TBNovo, a top-down tandem mass spectrum is utilized as a scaffold, and bottom-up tandem mass spectra are aligned to the scaffold to increase sequence coverage. Experiments on data sets of two proteins showed that TBNovo achieved high sequence coverage and high sequence accuracy.

4038 Background: The incidence of GEJC is increasing in North America and Europe, especially among white men. Many pts present with metastatic disease or relapse locally or systemically after resection of early-stage disease. The global phase 3 study TAGS (NCT02500043) demonstrated the efficacy and safety of FTD/TPI in previously treated pts with metastatic gastric cancer (mGC)/mGEJC. Here we report results in the mGEJC subgroup from TAGS. Methods: Pts with mGC/mGEJC treated with ≥2 prior chemotherapy regimens were randomized (2:1) to receive FTD/TPI (35 mg/m2 BID on days 1–5 and 8–12 of each 28-day cycle) or placebo, plus best supportive care. A preplanned efficacy and safety analysis was performed in pts with mGEJC. Results: Of 507 randomized pts, 145 (29%) had GEJC as the sole primary disease site (FTD/TPI, 98/337; placebo, 47/170). Of pts with mGEJC, 85% were male and 83% were white (overall population, 73% and 70%). Baseline characteristics were generally balanced for pts with mGEJC across treatment groups, except for fewer pts having prior gastrectomy (40% vs 55%) and more pts having received ≥3 prior regimens (74% vs 66%) in the FTD/TPI group than in the placebo group. FTD/TPI had an efficacy benefit in pts with mGEJC, and the FTD/TPI safety profile was similar in this subgroup and the overall population (table). Conclusions: FTD/TPI showed a manageable safety profile and efficacy benefit in pts with mGEJC in the TAGS trial, despite heavier pretreatment of the FTD/TPI than the placebo group. Clinical trial information: NCT02500043. [Table: see text]

4043 Background: The phase 3, randomized, double-blind, placebo-controlled study (TAGS) evaluated the efficacy and safety of FTD/TPI (35 mg/m² given orally twice a day on days 1–5 and 8–12 of a 28-day cycle) in mGC patients who had previously received≥2 prior regimens for advanced disease and demonstrated a clinically relevant and statistically significant benefit in OS and PFS with a predictable and manageable safety profile. HRQoL data and association between QoL and time to ECOG status deterioration (2 or more) are reported here. Methods: HRQoL was evaluated using EORTC QLQ-C30 and the gastric-specific module (QLQ-STO22) questionnaires at baseline and at every 4 weeks thereafter until treatment discontinuation. Prespecified key HRQoL were changes from baseline and time to deterioration. Changes ≥10 points were deemed clinically relevant. A time-dependent Cox-regression analysis was performed to evaluate the association of 10-point Global Health Status deterioration with worsening ECOG status. Results: Of 507 patients randomized, 332/337 (98.5%) of FTD/TPI and 164/170 (96.5%) of placebo had baseline QoL data. Overall compliance was 84% for both questionnaires. Demographic and disease were generally balanced between the two groups; QoL scores were also similar between groups. HRQoL was largely maintained during treatment in both arms for most items; mean changes from baseline remained under the 10-point threshold. Clinically relevant changes from baseline were observed only for pain relief at cycle 2 (favouring FTD/TPI); and improved role functioning at cycle 3 (favouring placebo). In a sensitivity analysis including death or progression as an event, FTD/TPI was associated with a positive trend suggesting a reduced risk of QoL deterioration across all scales compared to placebo (HRs ranged from 0.57 to 0.74. A 10-point Global Health Status deterioration was associated with a worsening ECOG status (HR, 95% CI, 1.5, 1.2 to 1.86). Conclusions: During the treatment period, HRQoL remained stable for most functional and symptom scales in both arms, suggesting that HRQoL is largely maintained with FTD/TPI. Treatment with FTD/TPI was associated with a positive trend toward a lower risk of QoL deterioration than placebo across all scales. Changes in QoL were informative for patients ‘expected ECOG status. Clinical trial information: NCT02500043.

e12631Background: SB3 was approved by the European Commission as a trastuzumab (TRZ) biosimilar. Here, we report safety and survival data with a follow-up of at least 12 treatment-free months after...

De novo sequencing of proteins and peptides is one of the most important problems in mass spectrometry-driven proteomics. A variety of methods have been developed to accomplish this task from a set of bottom-up tandem (MS/MS) mass spectra. However, a more recently emerged top-down technology, now gaining more and more popularity, opens new perspectives for protein analysis and characterization, implying a need for efficient algorithms to process this kind of MS/MS data. Here, we describe a method that allows for the retrieval, from a set of top-down MS/MS spectra, of long and accurate sequence fragments of the proteins contained in the sample. To this end, we outline a strategy for generating high-quality sequence tags from top-down spectra, and introduce the concept of a T-Bruijn graph by adapting to the case of tags the notion of an A-Bruijn graph widely used in genomics. The output of the proposed approach represents the set of amino acid strings spelled out by optimal paths in the connected components of a T-Bruijn graph. We illustrate its performance on top-down data sets acquired from carbonic anhydrase 2 (CAH2) and the Fab region of alemtuzumab.

509 Background: SB3, a proposed biosimilar to the originator trastuzumab (TRZ), demonstrated similarity to its originator in terms of biological activities and pharmacokinetic (PK) equivalence. This study compared SB3 to TRZ in terms of efficacy, safety, PK, and immunogenicity in patients treated by neoadjuvant therapy for HER2 positive early breast cancer (NCT02149524). Methods: Phase III, randomized, double blind, multicenter study compared neoadjuvant SB3 or TRZ for 8 cycles concurrently given with chemotherapy (docetaxel followed by 5-fluorouracil/epirubicin/cyclophosphamide). Then patients underwent surgery followed by 10 cycles of SB3 or TRZ. The primary endpoint was breast pathologic complete response (bpCR) rate. Equivalence was declared if the 90% confidence interval (CI) of the ratio or the 95% CI of the difference of the bpCR rates in the per-protocol set (PPS) were contained within the pre-defined equivalence margins (0.785, 1.546) and (-13%, 13%), respectively. Secondary endpoints were total pathologic complete response (tpCR), overall response rate (ORR), event-free survival, PK, immunogenicity, and safety. Results: 800 patients were included in PPS. The bpCR rates were 51.7% for SB3 and 42.0% for TRZ. The ratio of bpCR rate was 1.259 and its 90% CI was 1.112-1.426, within the pre-defined equivalence margin. The difference of bpCR rate was 10.70% and its 95% CI was 4.13-17.26; the lower margin was contained within, the upper margin was outside the pre-defined equivalence margin. Secondary endpoints were comparable between SB3 vs TRZ: tpCR rate (45.8% vs 35.8%); ORR (96.3% vs 91.2%). Safety was comparable between SB3 vs TRZ during neoadjuvant period: incidence of treatment-emergent adverse events (96.6% vs 95.2%), most commonly neutropenia, alopecia, and nausea; incidence of serious adverse events (10.5% vs 10.7%). PK equivalence was demonstrated and immunogenicity between SB3 vs TRZ was comparable (0.7% vs 0.0%). Conclusions: Equivalence was demonstrated between SB3 and TRZ based on the ratio of bpCR rates. Safety, PK, and immunogenicity were similar. Complete safety and survival data will follow. Clinical trial information: NCT02149524.

278 Background: We report the primary analysis of JAVELIN Gastric 100, which compared avelumab (anti–PD-L1) maintenance after 1L CTx vs continued CTx in patients (pts) with GC/GEJC. Methods: In this global, open-label, phase 3 trial (NCT02625610), eligible pts had previously untreated, unresectable, locally advanced/metastatic (LA/M) HER2− GC/GEJC. Pts without progressive disease (PD) after 12 weeks of 1L oxaliplatin/fluoropyrimidine induction were randomized 1:1 to avelumab 10 mg/kg Q2W switch maintenance or continued CTx, stratified by region (Asia vs non-Asia). Primary endpoint was overall survival (OS) post induction in all randomized or PD-L1+ (≥1% of tumor cells, 73-10 assay) pts. Results: 805 pts received induction CTx and 499 pts were randomized (avelumab, n = 249; CTx, n = 250). At data cutoff (Sep 13, 2019), minimum follow-up was 18 months. In the avelumab and CTx arms, median OS post induction/randomization was 10.4 months (95% CI 9.1-12.0) vs 10.9 months (95% CI 9.6-12.4), hazard ratio (HR) 0.91 (95% CI 0.74-1.11; p = 0.1779); 24-month OS rates were 22.1% (95% CI 16.8-28.0) vs 15.5% (95% CI 10.8-20.9), respectively. The HR for OS in PD-L1+ pts (n = 54) was 1.13 (95% CI 0.57-2.23). No OS trend was seen in Asian pts (n = 114; HR 0.90 [95% CI 0.59-1.36]) or other subgroups, except for a potential benefit with avelumab in pts with no metastatic sites at randomization (n = 60; HR 0.52 [95% CI 0.28-0.98]). Progression-free survival was similar between arms (HR 1.04 [95% CI 0.85-1.28]). In the avelumab vs CTx arms, objective response rates (post randomization only) were 13.3% (95% CI 9.3-18.1) vs 14.4% (95% CI 10.3-19.4), and 12-month rates for duration of response were 62.3% (95% CI 40.9-77.9) vs 28.4% (95% CI 13.2-45.7), respectively. Treatment-related adverse event rates (all grades/grade ≥3) were 61.3%/12.8% with avelumab and 77.3%/32.8% with CTx. Conclusions: Avelumab maintenance showed clinical activity and favorable safety vs continued CTx in pts with LA/M GE/GEJC; however, JAVELIN Gastric 100 did not meet its primary objective of demonstrating superior OS in the randomized or PD-L1+ population. Clinical trial information: NCT02625610.