Abstract CT508: Safety and efficacy of vibostolimab (vibo) plus pembrolizumab (pembro) in patients (pts) with cervical cancer naive to PD-1/PD-L1 inhibitors
Authors: Shapira-Frommer Ronnie , Perets Ruth , Voskoboynik Mark , Mileham Kathryn , Nagrial Adnan , Stein Brian , Chung Vincent , Gutierrez Martin , Chen Diana , Keenan Tanya , Rajasagi Mohini , Healy Jane , Rha Sun Young 
Published: June 2022

Background: The anti-TIGIT antibody vibo in combination with pembro was well tolerated across all doses in the dose-escalation phase of the ongoing phase 1 study in pts with advanced solid tumors (NCT02964013); promising antitumor activity of vibo + pembro was observed in anti-PD-1/PD-L1-naive NSCLC. We present initial results of the dose-expansion phase in pts with advanced cervical cancer naive to PD-1/PD-L1 inhibitors.

Methods: Pts with histologically confirmed, locally advanced, or metastatic cervical cancer who failed prior standard-of-care chemotherapy or who experienced early progression on definitive chemoradiation and were naive to PD-1/PD-L1 inhibitors were randomly assigned 1:1 to receive 1 of 2 doses of vibo (200 or 700 mg) + pembro (200 mg) Q3W for ≤35 cycles (~2 y) or until PD, toxicity, or pt withdrawal. Primary end points were safety and tolerability. Secondary and exploratory end points included ORR, DOR, and PFS by investigator review per RECIST v1.1.

Results: Median age of the 80 pts with cervical cancer was 49 y; 58% had an ECOG PS of 1; 53% received ≥2 prior lines of therapy; and 61% had PD-L1-positive tumors. 41 pts received vibo 200 mg, and 39 received vibo 700 mg. Median follow-up was 12 mo (range, 5-26). Treatment-related AEs (TRAEs) occurred in 27 pts in each treatment group (66%, vibo 200 mg; 69%, vibo 700 mg). The most frequent TRAEs (≥15%) were rash (22%), increased lipase (17%), and pruritus (17%) with vibo 200 mg + pembro and pruritus (28%), pyrexia (21%), rash (15%), and fatigue (15%) with vibo 700 mg + pembro. Grade 3 or 4 TRAEs occurred in 29% (vibo 200 mg + pembro) and 18% (vibo 700 mg + pembro). No deaths due to TRAEs were reported. Efficacy is reported in the Table.

Conclusions: Vibo + pembro was safe in pts with advanced cervical cancer. Antitumor activity was comparable between the 2 doses of vibo studied and responses were observed irrespective of PD-L1 status. Based on these data, the RP2D for vibo remains 200 mg Q3W.

Efficacy By Treatment Group By PD-L1 Statusa Vibo 200 mg + Pembro n = 41 Vibo 700 mg + Pembro n = 39 PD-L1-positive n = 49 PD-L1-negative n = 21 Confirmed ORR, % (95% CI) 15 (6-29) 23 (11-39) 20 (10-34) 14 (3-36) CR, n (%) 2 (5) 5 (13) 6 (12) 1 (5) PR, n (%) 4 (10) 4 (10) 4 (8) 2 (10) SD, n (%) 12 (29) 7 (18) 14 (29) 3 (14) PD, n (%) 18 (44) 19 (49) 20 (41) 12 (57) Median DOR, months (range)b Not reached (10 to 31+) Not reached (4+ to 35+) Not reached (4+ to 35+) Not reached (21 to 27+) Median PFS, months (95% CI) 2 (2-4) 2 (2-4) 4 (2-4) 2 (1-4) CR, complete response; DOR, duration of response; PD, progressive disease; ORR, objective response rate; PFS, progression-free survival; PR, partial response; SD, stable disease. aPD-L1 status was unknown in 10 patients; data were pooled across treatment groups. PD-L1 positivity was defined as combined positive score (CPS) ≥1 or when CPS was missing, as tumor proportion score ≥1% or mononuclear immune cell density score ≥2. b“+” indicates no PD present at the time of the last disease assessment.

Citation Format: Ronnie Shapira-Frommer, Ruth Perets, Mark Voskoboynik, Kathryn Mileham, Adnan Nagrial, Brian Stein, Vincent Chung, Martin Gutierrez, Diana Chen, Tanya Keenan, Mohini Rajasagi, Jane Healy, Sun Young Rha. Safety and efficacy of vibostolimab (vibo) plus pembrolizumab (pembro) in patients (pts) with cervical cancer naive to PD-1/PD-L1 inhibitors [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 CT508.