Tan, Daniel Shao-Weng

9089 Background: RET fusions are targetable oncogenic drivers in 1–2% of non-small cell lung cancer (NSCLC). ARROW (NCT03037385) supported the US FDA approval of pralsetinib, a highly potent oral selective RET inhibitor for RET-altered NSCLC and thyroid cancer. Here, we present updated results for a larger population of patients with RET fusion–positive NSCLC enrolled in ARROW. Methods: ARROW is a phase 1/2 open-label study conducted at 84 sites in 13 countries. Phase 2 expansion cohorts included patients with RET fusion–positive NSCLC. Initially, all treatment-naïve patients were not candidates for platinum-based therapy, a requirement removed by protocol amendment in July 2019. Primary objectives are overall response rate (ORR; blinded independent central review [BICR] per RECIST v1.1), assessed for patients with baseline measurable disease, and safety. Results: Updated analyses were completed as of Nov 6, 2020 (data cut-off), for patients who initiated pralsetinib 400 mg QD by May 22, 2020 (enrollment cut-off). Efficacy results, including analyses for treatment-naïve patients enrolled after eligibility criteria were revised to allow candidates for platinum-based therapy, are shown in the Table. Conclusions: Pralsetinib showed rapid, potent, and durable clinical activity in patients with RET fusion-positive NSCLC (regardless of prior therapies), including poor prognosis patients not eligible for platinum-based therapy. Overall, pralsetinib was well-tolerated. These data highlight the need for RET testing early in the course of disease to identify candidates who may benefit from treatment with pralsetinib. Clinical trial information: NCT03037385. [Table: see text]

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]

3594 Background: Selpercatinib (LOXO-292) is a highly selective and potent small molecule RET kinase inhibitor. Here we report an update on the efficacy and safety of selpercatinib in RET-mutant medullary thyroid cancer (MTC). Methods: Patients with RET-mutant MTC were enrolled to the Phase 1/2 LIBRETTO-001 trial (NCT03157128), a global, multicenter trial (16 countries, 89 sites). Following the Phase 1 dose escalation portion of the trial, patients received the recommended dose of 160 mg orally twice daily. Each cycle was 28 days. The primary endpoint was objective response rate (ORR) per RECIST 1.1. Secondary endpoints included duration of response (DoR) and safety. Per health authority agreement, the primary analysis set was defined as the first 55 consecutively enrolled patients previously treated with multikinase inhibitors cabozantinib and/or vandetanib. Patients naïve to cabozantinib and vandetanib treatment were analyzed separately. All analyses were based on a 16-Dec-2019 data cutoff date. Results: In the primary analysis set of prior cabozantinib and/or vandetanib-treated patients with MTC (n = 55), the ORR by investigator assessment was 62% (95% CI 47.7–74.6, n = 34/55) and the median DoR was not reached (95% CI 18.4 months–not estimable) despite a median follow-up of 14.8 months. In cabozantinib/vandetanib treatment-naïve patients (n = 88), the ORR by investigator assessment was 69% (95% CI 58.6–78.7, n = 61/88, including 2 responses pending confirmation). Of the 59 confirmed responding patients, with a median follow-up of 8 months, responses were ongoing for 57 responders at the time of the analysis. In the safety analysis set consisting of all selpercatinib dosed patients (N = 702), the most common treatment-related adverse events (TRAEs) that occurred in ≥15% of patients were dry mouth (33.3%), increased AST (24.5%), increased ALT (23.8%), hypertension (23.2%), diarrhea (19.7%), and fatigue (16.8%). Only 2% (14 of 702) of patients discontinued selpercatinib for TRAEs. Conclusions: Selpercatinib use was associated with marked and durable antitumor activity in prior cabozantinib and/or vandetanib-treated patients and in cabozantinib/vandetanib-naïve patients with RET-mutant MTC, with the majority of responses ongoing in both cohorts. Selpercatinib was well tolerated. Efficacy data assessed by independent review committee based on the 16-Dec-2019 data cutoff date will be presented. Clinical trial information: NCT03157128 .