Mansfield, Aaron S.

9520 Background: Capmatinib (INC280) has shown promising efficacy in patients (pts) with MET exon 14 ( METex14)–mutated NSCLC who were pretreated (cohort 4) or treatment (tx)-naïve (cohort 5b) in the ongoing, multicohort, phase 2 GEOMETRY mono-1 study. We report the results for pts enrolled in the expansion cohort 6 with either high-level MET amplification (gene copy number [GCN] ≥10) or METex14 mutation (any MET GCN) whose disease progressed on 1 prior line of systemic therapy. Methods: Adult pts (≥18 years), ECOG PS 0–1 who had ALK and EGFR wt, stage IIIB/IV NSCLC (any histology) received capmatinib tablets 400 mg twice daily (with or without food). Key efficacy endpoints were overall response rate (ORR) and duration of response (DOR) by blinded independent review committee (BIRC) per RECIST v1.1. Other secondary endpoints included investigator-assessed ORR, DOR, disease control rate (DCR), progression-free survival (PFS; BIRC and investigator assessment) and safety. Results: As of Jan 6, 2020, 34 NSCLC pts with METex14 mutation (n = 31) or high-level MET amplification (n = 3) were included in this analysis. Tx was ongoing for 38.2% of pts. In METex14-mutated NSCLC pts, per BIRC assessment: ORR was 48.4%, median DOR was 6.93 months (mo, not yet mature, 95% CI: 4.17–NE) and median PFS was 8.11 mo (not yet mature, 95% CI: 4.17–9.86). Investigator-assessed responses were similar to BIRC assessment (Table). Only 3 pts with high-level MET amplification were included in this cohort due to challenges in enrollment. All 3 pts had stable disease per BIRC assessment and were on treatment for 48, 85 and 97 days. Most common AEs (≥25%, all grades, N = 34) were peripheral edema (64.7%), nausea (35.3%), fatigue (29.4%), back pain (26.5%) and vomiting (26.5%). Data for pts with brain metastasis will be presented at the ASCO 2020 meeting. Conclusions: Capmatinib was confirmed to be efficacious in 2nd line, METex14-mutated NSCLC pts. This is the first cohort where capmatinib has been administered without fasting restriction and data confirm the favorable safety profile. Clinical trial information: NCT02414139 . [Table: see text]

3552 Background: Delta-like 3 (DLL3) is highly and specifically expressed in solid tumors, such as neuroendocrine carcinomas (NECs), malignant melanoma (MM), and medullary thyroid carcinoma (MTC). Rovalpituzumab tesirine (Rova-T) is a DLL3-targeting antibody-drug conjugate. Methods: This Phase 1/2 study (NCT02709889) enrolled patients with relapsed/refractory DLL3+ (>1% by IHC) advanced solid tumors and ECOG performance status of 0-1. Rova-T was given IV at 0.2, 0.3, or 0.4 mg/kg on d 1 of each 6-wk cycle (q6wk) for dose escalation (3+3 design) in disease-specific cohorts in Phase I. The recommended Phase 2 dose (RP2D) was tested in Phase II. Safety and dose-limiting toxicities (DLTs) were primary endpoints; efficacy outcomes were secondary endpoints. Results: The study enrolled 200 patients; 101 had NECs (large cell NEC [n=13], neuroendocrine prostate cancer [n=21], high-grade gastroenteropancreatic NEC [n=36], other [n=31]) and 99 had other solid tumors (MM [n=20], MTC [n=13], glioblastoma [GBM; n=23], other [n=43]). The median age was 61 y (range, 28-84); 63% were male. The RP2D was 0.3 mg/kg q6wk for 2 cycles in all cohorts. There were 7 DLTs in 5 patients: 2 with 0.2 mg/kg (Grade [Gr] 3 photosensitivity reaction, Gr 3 dyspnea), 2 with 0.3 mg/kg (1 with Gr 2 effusion, Gr 3 tumor lysis syndrome, and Gr 3 rhabdomyolysis; 1 with Gr 4 kidney injury), and 1 with 0.4 mg/kg (Gr 4 thrombocytopenia). Despite only 1 DLT identified with 0.4 mg/kg, the totality of the safety data suggested that this dose is not well tolerated. Common adverse events (AEs) in patients given 0.3 mg/kg (n=145) are shown (Table). Serious AEs occurred in 77/145 patients (53%), most commonly (≥3%) malignant neoplasm progression (n=18; 12%), pleural effusion (n=7; 5%), pericardial effusion (n=6; 4%), and dyspnea (n=5; 3%). The objective response rate (ORR) was 11% (21/200): 14 had NEC, 2 had MM, 2 had MTC, 2 had small cell carcinoma (SCC) not of lung origin (all partial responses), and 1 had GBM (complete response). In patients with NECs given 0.3 mg/kg, ORR, clinical benefit rate, and progression-free survival trended in favor of those with high DLL3-expressing tumors (≥50% by IHC) which represented 51% of NECs. Conclusions: Rova-T was tolerable in patients with advanced solid tumors at 0.3 mg/kg q6wk for 2 cycles. Antitumor activity was observed in patients with NEC, MM, MTC, SCC, and GBM. Clinical trial information: NCT02709889 . [Table: see text]

3011 Background: Antibody blockade of semaphorin 4D (SEMA4D, CD100) promotes tumoral dendritic cell and CD8+ T cell infiltration and reduces function and recruitment of immunosuppressive myeloid cells. Importantly, these mechanisms to overcome immune exclusion and suppression have been shown to complement immune checkpoint therapies in preclinical models. Pepinemab is an IgG4 humanized monoclonal antibody targeting semaphorin 4D. The CLASSICAL-Lung clinical trial tests the combination of pepinemab with avelumab to couple T cell activation via checkpoint inhibition with beneficial modifications of the immune microenvironment via pepinemab. Methods: This phase 1b/2, single arm, first-in-human study is designed to evaluate the safety, tolerability and efficacy of pepinemab with avelumab in 62 patients (pts) with advanced (stage IIIB/IV) non-small cell lung cancer (NSCLC), including immunotherapy-naïve (ION) pts and pts whose tumors progressed following immunotherapy (IOF). Results: Among 21 evaluable ION pts, 5 experienced partial response (PR), 3 pts had clinical benefit ≥ 1 year, and the disease control rate (DCR) is 81%. Pts enrolled in this study were observed to have lower PD-L1 expression relative to prior single agent studies (likely due to approval of pembrolizumab for first line therapy). We, therefore, performed subgroup analysis for response by PD-L1 status. The objective tumor response (ORR) in the PD-L1 negative and low population ( < 80% TPS by Dako 73-10 assay) appears to be approximately 2-2.5 fold greater with combination therapy than with historical single agent immune checkpoint controls. Notably, 97% of pts who experienced PR or SD were reported to have tumors with negative or low PD-L1 expression. Among 29 evaluable IOF pts, the combination resulted in 59% DCR, including 2 PR and 7 patients with durable clinical benefit of ≥ 23 weeks. Biomarker analysis of pre- and on-treatment biopsies confirmed increased CD8+ T cell density correlating with response. Surprisingly, analysis of myeloid-derived suppressor cells (MDSCs) revealed a relative paucity of these cells in pretreatment NSCLC biopsies as compared to other cancer indications such as HNSCC. Conclusions: This trial is nearing completion with only 5 of 62 subjects remaining on study. Preliminary data suggest the combination is well tolerated and shows signs of increased antitumor activity, particularly in PD-L1 negative or low tumors. Updated clinical response data and immunophenotypic analyses will be presented. Clinical trial information: NCT03268057 .

109 Background: RET gene fusions are targetable oncogenic drivers in multiple tumor types, including up to 20% of papillary thyroid cancers (PTC). Pralsetinib is an investigational, highly potent, selective inhibitor of oncogenic RET alterations. In the registration-enabling Phase 1/2 ARROW study (NCT03037385), pralsetinib demonstrated an overall response rate (ORR; response-evaluable patients [REP], central review) of 73% (19/26) in treatment-naïve patients and 61% (49/80; 2 pending confirmation) in platinum-exposed patients with RET fusion+ non-small cell lung cancer (NSCLC) and was well tolerated (data cut-off November 18, 2019). We provide an update on the clinical activity of pralsetinib in other RET fusion+ solid tumor types. Methods: ARROW consists of a phase 1 dose escalation (30–600 mg once [QD] or twice daily) followed by a phase 2 expansion (400 mg QD) in patients with advanced RET-altered solid tumors. Primary objectives were ORR and safety. Results: As of November 18, 2019, 29 patients with metastatic solid tumor types other than NSCLC (16 PTC, 1 undifferentiated thyroid, 3 pancreatic, 3 colon, 6 other) bearing a RET fusion have received pralsetinib. Efficacy data are presented for REP enrolled by July 11, 2019. In patients with thyroid cancer that is RET fusion+, ORR (investigator assessment) was 75% (9/12; all confirmed). Median (range) duration of response (DOR) was 14.5 (3.7+, 16.8) months (mo), with 67% of responding patients continuing treatment. Two patients with stable disease were continuing treatment at 11.5+ and 19.3+ mo. In other RET fusion+ cancers, ORR was 60% (3/5; all confirmed) with partial responses in 2/2 patients with pancreatic cancer (DOR 5.5, 7.4+ mo) and 1 patient with intrahepatic bile duct carcinoma (DOR 7.5 mo). Two patients with colon cancer had stable disease for 7.3 and 9.3 mo. Responses were observed across multiple fusion genotypes. In the entire safety population (all patients treated with 400 mg QD pralsetinib, regardless of diagnosis; n = 354), most treatment-related adverse events (TRAEs) were grade 1-2, and included increased aspartate aminotransferase (31%), anemia (22%), increased alanine aminotransferase (21%), constipation (21%) and hypertension (20%). Only 4% of patients in the safety population discontinued due to TRAEs. Conclusions: Pralsetinib demonstrated broad and durable antitumor activity across multiple advanced solid tumor types, regardless of RET fusion genotype, and was well tolerated. The study is ongoing and still enrolling patients in this cohort. Clinical trial information: NCT03037385.

Abstract Purpose Delta-like protein 3 (DLL3) is being developed as a predictive biomarker for DLL3-targeting antibody-drug conjugate and other therapies. Given the neuroendocrine features of Merkel cell carcinoma (MCC), we sought to evaluate DLL3 expression and its role in MCC. Experimental Design Formalin-fixed and paraffin-embedded MCC cases were consecutively selected. Immunohistochemistry was performed for DLL3 (SC16.65 antibody) and polyomavirus large T-antigen (sc-136172 antibody). Slides were read out for percentage of positive tumor cells. Cox proportional hazards model was applied to assess the association between DLL3 expression and overall survival (OS). A patient with a DLL3-expressing MCC was treated with rovalpituzumab tesirine (Rova-T) in the “other tumor” cohort of NCT02709889 and assessed for response. Results The median H-score of DLL3 expression of 65 patients included was 60 (interquartile range, 30–100). Fifty-eight cases (89%) had ≥1% tumor cells positive for DLL3 expression with any intensity, of which the median DLL3 expression was 50% (interquartile range, 25%–70%). Thirty-four cases (52%) had ≥50% tumor cells positive for DLL3 expression with any intensity. Higher H-score of DLL3 expression was associated with higher polyomavirus nuclear expression (p = .003) when it was dichotomized to negative versus positive. H-score of DLL3 expression did not predict OS of patients with MCC (p = .4) after being adjusted for common clinicopathological factors. A patient treated with Rova-T for refractory metastatic MCC achieved partial response. Conclusions DLL3 overexpression is very common in MCC by immunohistochemistry. The response to treatment suggests that DLL3 expression may have predictive relevance for DLL3-targeting therapies in MCC. Implications for Practice Delta-like protein 3 (DLL3) is being developed as a predictive biomarker to identify patients for treatment with DLL3-targeting agents. Merkel cell carcinoma (MCC) is an aggressive neuroendocrine carcinoma of the skin. It was found that DLL3 overexpression is very common in MCC by immunohistochemistry and significantly associated with Merkel cell polyomavirus expression. Despite the lack of prognostic significance in this cohort, DLL3 expression may have predictive relevance for DLL3-targeting therapies in MCC. The high levels of DLL3 expression in a subset of MCC may potentially be used to select patients to receive DLL3-targeting therapies.

e20077 Background: Small cell lung cancer (SCLC) accounts for about 10% to 15% of lung cancers among women and men. Though heavily associated with smoking, its incidence in women is rapidly increasing despite a decline in cigarette exposure. Given the changing demographics of SCLC and hormonal factors associated with other forms of lung cancer, we studied differences between sexes in SCLC. Methods: Utilizing the National Cancer Database, we identified all incident SCLC cases from 2004 to 2014. Patients were classified as limited stage (LS) or extensive stage (ES). Women were stratified by menopausal status (≥55 years = postmenopausal). Kaplan-Meier method and Cox regression were used for overall survival (OS) and multivariable analysis. Results: 161,978 patients were identified. No significant sociodemographic differences were observed between sexes. The majority of patients were non-Hispanic whites (89.1%), followed by non-Hispanic blacks (7.5%). Men were more likely to be diagnosed with ES disease than women (63% vs. 56%). Both sexes initiated treatment within a similar time frame from diagnosis (chemotherapy, median: 18 days, IQR 8-32). Women had better median OS compared to men in both LS (15.2 vs. 12.7 months, HR: 0.85, 95% CI 0.83-0.86, p < 0.0001) and ES (6.4 vs. 5.7 months, HR: 0.88, 95% CI 0.87-0.90, p < 0.0001). No racial or ethnic disparities in OS were observed, overall and when examined within sex and disease stage groups. Differences between sexes in OS were also observed when comparing patients within the same racial/ethnic group (women having better OS). When divided by menopausal status, postmenopausal women with LS and ES had worse OS than premenopausal women (14.7 vs. 22 months, HR: 1.50, 95% CI 1.44-1.56; 6.1 vs. 9.8 months, HR: 1.41, 95% CI: 1.37-1.46, respectively). We also observed worse OS in older men when divided by age ( < 55 years and ≥55 years). In multivariable analysis, older age, postmenopausal status, and Medicaid as primary insurance were associated with worse OS for both LS and ES. Conclusions: In this large cohort, women with SCLC had better OS compared to men. Post-menopausal women had worse OS compared to pre-menopausal women. Since older men had a similar trend of worse survival compared to younger men, age might exert a more significant influence on survival than hormonal status in SCLC. Further studies with data on sexual hormone levels are necessary to better understand their role in women with SCLC.

2551 Background: Protein kinase C iota (PKCi) is overexpressed in non-small cell lung (NSCLC), ovarian and pancreatic cancers and promotes tumorigenesis. The gold compound aurothiomalate (ATM) inhibits downstream activation of Rac1 by PKCi. We sought to determine the maximum tolerated dose (MTD) of ATM. Methods: We conducted a phase I dose escalation trial of ATM in patients with NSCLC, ovarian or pancreatic cancer. In the dose escalation cohort patients received ATM IM weekly for three cycles (cycle duration 4 weeks) at 25 mg, 50 mg or 75 mg in a 3+3 design. The dose was not escalated for individual patients. Up to 9 subjects were allowed to enroll in the expansion cohort at the MTD. Blood samples were analyzed for elemental gold levels. Patients were evaluated for response every eight weeks with computed tomography using modified response evaluation criteria in solid tumors. Results: Fifteen patients, all pretreated, enrolled in this study. There were ten patients with NSCLC, four with ovarian cancer and one with pancreatic cancer. Six patients were treated at the 25 mg dose, 6 patients at 50 mg, and 2 at 75 mg. There was 1 dose limiting toxicity (DLT) at 25 mg (hypokalemia), 1 DLT at 50 mg (urinary tract infection), and none at 75 mg. There were 3 grade 3 hematologic toxicities in the dose escalation cohort. The recommended MTD of ATM is 50 mg, and 1 subject was treated in the expansion cohort at 50 mg. Patients received treatment for a median of 2 cycles (range 1-3). The best response observed was stable disease in 2 subjects. There appeared to be a dose-related accumulation of steady-state plasma concentrations of gold with concentrations exceeding 20 µM after one month of therapy with 75 mg of ATM and after 2 months of therapy with 50 mg of ATM, consistent with linear pharmacokinetics. Conclusions: In summary, this phase I study was successful in identifying ATM 50 mg IM weekly as the MTD. In this heavily pre-treated group of patients in who we observed at best stable disease, it remains unclear whether future investigations that target PKCi should focus on single agent ATM, combination therapy with ATM, or other PKCi inhibitors that are currently in development. Clinical trial information: NCT00575393.