256 Single-agent zalifrelimab (anti-CTLA-4) shows clinical benefit in rare tumors – case report from phase 2 study (NCT03104699)

BackgroundZalifrelimab is a fully human monoclonal antibody against cytotoxic T-lymphocyte -associated protein 4 (CTLA-4). Preliminary data demonstrated clinical benefit and tolerability, as monotherapy, in patients with recurrent solid tumors including rare tumor types. Previously presented Phase I data reported one durable complete response in recurrent cutaneous angiosarcoma (cAS).1 Here we report additional clinical responses from an ongoing Phase 2 study of zalifrelimab monotherapy including clinical benefit in rare solid tumors.MethodsIn an ongoing, phase 2 study (NCT03104699), the safety and efficacy of zalifrelimab, as monotherapy, was evaluated in patients who progressed on prior anti-PD-1/L1 treatment. All patients were treated intravenously (IV) with zalifrelimab at 1 mg/kg every 3 weeks until disease progression or up to 2 years.ResultsOverall, 44 patients were treated and 29 patients were response-evaluable at the time of report. In patients with refractory solid tumors treated with zalifrelimab, we report a disease control rate (CR, PR, and SD) of 51.7%, objective response rate (ORR) of 10.3% (3/29), disease stabilization of 41.3% (12/29). Clinical activity was observed in five solid tumors considered rare, including; cAS (N=1), glucagonoma (N=1), chondrosarcoma (N=1), spindle-cell sarcoma (N=1) and fibroblastic sarcoma (N=1). In these rare tumors, durable partial responses of 45 and 30 weeks were observed in cAS of the scalp with lymph node metastases and glucagonoma, respectively. Both patients remain on zalifrelimab with no evidence of disease progression. Additionally, durable disease stabilization was observed in a patient with spindle-cell sarcoma. Patients with chondrosarcoma and fibroblastic sarcoma progressed on therapy. Zalifrelimab was well tolerated with the most commonly reported treatment-related adverse events including fatigue, nausea, anemia, diarrhea and vomiting, consistent with the drug class. Most events were mild or moderate and resolved with standard treatments.ConclusionsOur data demonstrates the potential for Zalifrelimab to promote meaningful clinical benefit in difficult to treat tumors, including patients that progress on prior PD-1/PD-L1 therapy or chemotherapy. Notably, responses were observed in rare tumor types such as recurrent cutaneous angiosarcoma and glucagonoma. Treatment with zalifrelimab is safe and well tolerated in patients with advanced malignancies.Trial RegistrationNCT03104699.ReferenceVaia Florou, Andrew E Rosenberg, Eric Wieder, Krishna V. Komanduri, Despina Kolonias, Mohamed Uduman, John C Castle, Jennifer S. Buell, Jonathan C. Trent and Breelyn A. Wilky Journal for Immunotherapy of Cancer 2019 7:213

RaPiDS (GOG-3028): randomized Phase II study of balstilimab alone or in combination with zalifrelimab in cervical cancer.

Balstilimab (anti-programmed death 1) and zalifrelimab (anti-CTLA-4) are two new checkpoint inhibitors that have emerged as promising investigational agents for the treatment of cervical cancer, particularly in the setting of previously-treated, recurrent/metastatic disease. Here we describe the rationale and design of RaPiDS (NCT03894215), a two-arm Phase II study evaluating the safety, tolerability and efficacy of balstilimab administered alone or in combination with zalifrelimab in patients with advanced cervical cancer who progressed after first-line, platinum-based chemotherapy. Patients will be randomized in a 1:1 ratio. The primary end point is objective response rate, and key secondary objectives include safety, duration of response, progression-free survival, overall survival and quality of life outcomes

Results from a phase 1a/1b study of botensilimab (BOT), a novel innate/adaptive immune activator, plus balstilimab (BAL; anti-PD-1 antibody) in metastatic heavily pretreated microsatellite stable colorectal cancer (MSS CRC)

LBA8 Background: BOT promotes optimized T cell priming, activation and memory formation by strengthening antigen presenting cell/T cell co-engagement. As an Fc-enhanced next-generation anti–CTLA-4 antibody, BOT also promotes intratumoral regulatory T cell depletion and reduces complement fixation. We present results from patients with MSS CRC treated with BOT + BAL in an expanded phase 1a/1b study; NCT03860272. Methods: Patients (pts) with metastatic MSS CRC received BOT 1 or 2 mg/kg every 6 weeks (Q6W) + BAL 3 mg/kg every 2 weeks. Crossover from monotherapy to combination therapy was permitted (rescue) as well as fixed-dosing (150 mg BOT Q6W + 450 mg BAL every 3 weeks). Results: Fifty-nine combination pts were evaluable for efficacy/safety (treated as of 19 May 2022 with ≥1 Q6W imaging assessment), including one rescue and one fixed-dose pt. Median pt age was 57 (range, 25-83), 58% were female, and 76% received at least three prior lines of therapy including prior immunotherapy (34%). Median follow-up was 6.4 months (range, 1.6-29.5). In all pts, objective response rate (ORR) was 22% (95% CI, 12-35), disease control rate (DCR) was 73% (95% CI, 60-84), and median duration of response (DOR) was not reached (NR), with 9/13 responses ongoing. The 12-month overall survival (OS) rate was 61% (95% CI, 42-75), with median OS NR. Of the 13 responders, 9 had RAS mutations (7 KRAS, 2 NRAS), 0 had BRAF mutations, 0/10 had a TMB of ≥10 mutations/Mb, and 1/7 was PD-L1 positive (≥1% combined positive score). A subgroup analysis was conducted by the dose of BOT received . In 1 mg/kg pts (n=8), ORR was 38% (3/8; 95% CI, 9-76) and DCR was 100% (8/8; 95% CI, 63-100); in 2 mg/kg pts (n=50), ORR was 20% (10/50; 95% CI, 10-34) and DCR was 70% (35/50; 95% CI, 55-82). All grade treatment-related adverse events (TRAEs) occurred in 88% of pts, including grade 3 in 32%, and grade 4 in 2% of pts. Diarrhea/colitis was the only grade 3/4 TRAE occurring in more than three pts (15% grade 3, 2% grade 4). The most common grade 3 TRAEs outside of diarrhea/colitis were fatigue (5%) and pyrexia (5%). There were no grade 5 TRAEs reported. Fifteen percent of pts had a TRAE leading to discontinuation of BOT alone and 12% had a TRAE leading to discontinuation of both BOT + BAL. Conclusions: In heavily pretreated metastatic MSS CRC pts, BOT + BAL continues to demonstrate promising clinical activity with durable responses and was well tolerated with no new immune-mediated safety signals. A larger pt set, analyses by subgroup, and additional translational data will be presented at the meeting. A randomized phase 2 trial in MSS CRC pts is enrolling (NCT05608044). Clinical trial information: NCT03860272