Florou, Vaia

Abstract Purpose: The addition of MEK inhibition (MEKi) to programmed cell death ligand 1 (PD-L1) blockade improves progression-free survival (PFS) in patients with advanced biliary tract cancer. Although MEK inhibitors may increase tumor cell immunogenicity, they can impair T-cell priming/effector function, limiting combination efficacy. We hypothesized that the addition of a CD27 agonist could restore T-cell function and enhance antitumor immunity in this combination. Patients and Methods: We conducted a randomized, phase II trial evaluating atezolizumab (840 mg, intravenously, days 1 and 15) in combination with the CD27 costimulatory monoclonal antibody [CDX-1127/varlilumab (3 mg/kg, intravenously, days 1 and 15)], with/without the addition of an MEK inhibitor [cobimetinib (60 mg, orally, daily, days 1–21, off days 22–28)] in unresectable biliary tract cancer following at least one metastatic therapy. Overall response rate (ORR) and PFS were coprimary endpoints. Treatment-related changes in CD8+ tumor-infiltrating lymphocytes (TIL) were the primary correlative outcomes. Results: The trial was closed early following interim preplanned ORR analysis. At closure, 57 patients had been enrolled [n = 29 in the cobimetinib + atezolizumab + varlilumab (CAV) arm; n = 28 in the atezolizumab + varlilumab (AV) arm]. A majority (67%) had intrahepatic cholangiocarcinoma, and 32% were immunotherapy experienced. Both regimens were well tolerated without new safety signals. Objective responses were rare [0% (CAV); 3.8% (AV)]. The median PFS (mPFS) was 2.40 (CAV) and 1.84 (AV) months [hazard ratio (HR), 0.67; 95% confidence interval (CI), 0.38–1.18]. Among immunotherapy-experienced patients, the mPFS was 3.62 (CAV) and 1.84 (AV) months (HR, 0.54; 95% CI, 0.18–1.62). Treatment with CAV increased intratumoral CD8+ T-cell density compared with treatment with AV. Conclusions: The combinations of atezolizumab and varlilumab with/without cobimetinib were safe, but neither meaningfully improved outcomes in biliary tract cancer treated in the later lines. Correlative tissue studies validated preclinical work that MEKi increases CD8+ TILs.

4017 Background: Combined MEK inhibition (MEKi) and PD-L1 blockade significantly improved progression-free survival (PFS) versus PD-L1 monotherapy in patients with advanced biliary tract cancer (BTC) following first-line chemotherapy (NCT03201458). Further study has shown MEKi enhances tumor immunogenicity but impairs host T cell activation/priming. The addition of immune agonists, e.g. a CD27 agonist, can rescue T cell function in the setting of systemic MEKi in vivo and may be an effective strategy to optimize MEKi’s immunomodulatory potential when used in combination with checkpoint blockade. Methods: We conducted a randomized ph 2 trial (NCT04941287) evaluating Atezolizumab in combination with the CD27 immune agonist (CDX-1127 [Varlilumab]) with or without the addition of a MEKi (Cobimetinib) in patients with unresectable, previously treated, BTC. Adults with pathologically-confirmed BTC, s/p at least 1 prior line (no more than 2) of systemic therapy, measurable disease, and ECOG PS ≤1 were enrolled. Patients who had received previous PD-[L]1 were eligible. The study was planned for 64 evaluable subjects randomized in a 1:1 ratio, stratified by BTC site, to either AV (Atezolizumab [840mg IV days 1,15])+ Varlilumab [3mg/kg IV days 1, 15]) or CAV (Cobimetinib [60mg oral daily days 1-21, off 22-28] + Atezolizumab + Varlilumab). Overall response rate (ORR) and PFS were co-primary endpoints. The primary correlative outcome was treatment-related changes in CD8+ infiltrating T cells. Results: A preplanned interim analysis based on objective response rates did not meet the threshold for continuance in either treatment arm, so the trial was closed early for futility. In total, 57 patients were enrolled (n = 29 [CAV], n = 28 [AV], 67% had intrahepatic cholangiocarcinoma, and 33% had received previous PD-[L]1. Both CAV and AV regimens were well-tolerated without new safety signals. Adding CDX-1127 did not appear to meaningful increase immunotoxicity beyond established PD-L1 toxicity profiles. ORR was 0% (CAV) and 4% (AV). With a median follow up time of 6.2 months, median PFS was 2.2 (CAV) and 1.8 (AV) months (HR 0.71 [0.40,1.25]). In PD[L]1-experienced patients, median PFS was 3.6 (CAV) and 1.7 (AV) months (HR 0.44 [0.14,1.33]). Median OS was 10.2 (CAV) and 6.1 (AV) months (HR 0.76 [0.37,1.55]). In PD[L]1-experienced patients, median OS was 6.4 (CAV) and 4.4 (AV) months for CAV and AV (HR 0.68 [0.19,2.42]). Primary correlative endpoint and updated survival will be reported at time of meeting. Conclusions: The combination of Atezolizumab and Varlilumab with or without Cobimetinib was safe but did not improve clinical outcomes in advanced stage BTC patients treated in later lines. Though not statistically significant, treatment with CAV demonstrated numerically favorable PFS/OS compared AV among immunotherapy-experienced patients. Clinical trial information: NCT03201458 .

4009 Background: Oncogenic FGFR2 alterations (fusions/rearrangements (f/r), amplifications, mutations) represent a broad therapeutic opportunity as they drive multiple solid tumors, particularly cholangiocarcinoma (CCA). However, off-isoform toxicity and on-target resistance limit the benefit of approved pan-FGFR inhibitors (FGFRi). RLY-4008 is the first potent, highly selective, oral FGFR2 inhibitor designed to overcome these limitations by targeting FGFR2 driver alterations and resistance mutations. Here, we present updated dose escalation results from ReFocus (NCT04526106), a seamless Phase I/II, open label study evaluating the safety and preliminary efficacy of RLY-4008 in patients (pts) with advanced, FGFR2-altered solid tumors. Methods: Adult pts received RLY-4008 BID, QD, QD discontinuous on a 4-week (wk) cycle following a Bayesian Optimal Interval design. Treatment-related adverse events (TRAEs), PK, ctDNA and anti-tumor activity (RECIST v1.1) were assessed. Results: As of 30 Jan 23, 116 pts (82 f/r, 27 mutation, 6 amplification) received RLY-4008 at doses of 20-200 mg/day, including 91 with CCA. 50% had prior FGFRi, and median lines of prior therapies was 3 (1-15). 28/46 ct-DNA-evaluable pts with CCA with prior FGFRi had ≥1 baseline resistance mutation, most commonly at FGFR2 N549X (23/46) or V564X (17/46). RLY-4008 had favorable PK with doses ≥40 mg QD providing FGFR2 occupancy ≥90%. 70 mg QD was the RP2D based on PK, safety, anti-tumor activity and exposure-dependent tumor regressions in FGFRi-naïve CCA f/r pts. Anti-tumor activity was observed in CCA and solid tumors across doses and FGFR2 alterations with radiographic tumor reductions in 74 (64%), SD/PR in 83 (72%), including 4/4 (100%) FGFRi-naïve CCA f/r pts at RP2D achieving confirmed PR. Clinically meaningful disease control and durable responses were observed in pts with FGFR2 f/r CCA. Overall, median treatment duration was 24 wks (range <1-108 wks). 105 pts discontinued (PD (81%), AE (3%), other (7%)). Across doses, most common TRAEs were low-grade PPE (57%), stomatitis (56%), dry mouth (38%), alopecia (28%), and dry eye (22%). No grade 4/5 TRAEs were observed. Conclusions: These encouraging dose escalation data confirm the broad therapeutic potential of highly selective FGFR2 targeting with RLY-4008 by demonstrating encouraging initial efficacy across FGFR2-altered solid tumors and genomic alterations, with a differentiated safety profile that avoids FGFR1- and FGFR4-related toxicity. Phase 2 of ReFocus continues across solid tumors and with registrational intent in FGFRi-naïve, FGFR2 f/r CCA. Clinical trial information: NCT04526106 . [Table: see text]

PURPOSE Compared with people living without HIV (PWOH), people living with HIV (PWH) and cancer have traditionally been excluded from immune checkpoint inhibitor (ICI) trials. Furthermore, there is a paucity of real-world data on the use of ICIs in PWH and cancer. METHODS This retrospective study included PWH treated with anti–PD-1- or anti–PD-L1-based therapies for advanced cancers. Kaplan-Meier method was used to estimate overall survival (OS) and progression-free survival (PFS). Objective response rates (ORRs) were measured per RECIST 1.1 or other tumor-specific criteria, whenever feasible. Restricted mean survival time (RMST) was used to compare OS and PFS between matched PWH and PWOH with metastatic NSCLC (mNSCLC). RESULTS Among 390 PWH, median age was 58 years, 85% (n = 331) were males, 36% (n = 138) were Black; 70% (n = 274) received anti–PD-1/anti–PD-L1 monotherapy. Most common cancers were NSCLC (28%, n = 111), hepatocellular carcinoma ([HCC]; 11%, n = 44), and head and neck squamous cell carcinoma (HNSCC; 10%, n = 39). Seventy percent (152/216) had CD4+ T cell counts ≥200 cells/µL, and 94% (179/190) had HIV viral load <400 copies/mL. Twenty percent (79/390) had any grade immune-related adverse events (irAEs) and 7.7% (30/390) had grade ≥3 irAEs. ORRs were 69% (nonmelanoma skin cancer), 31% (NSCLC), 16% (HCC), and 11% (HNSCC). In the matched mNSCLC cohort (61 PWH v 110 PWOH), 20% (12/61) PWH and 22% (24/110) PWOH had irAEs. Adjusted 42-month RMST difference was –0.06 months (95% CI, –5.49 to 5.37; P = .98) for PFS and 2.23 months (95% CI, –4.02 to 8.48; P = .48) for OS. CONCLUSION Among PWH, ICIs demonstrated differential activity across cancer types with no excess toxicity. Safety and activity of ICIs were similar between matched cohorts of PWH and PWOH with mNSCLC.