2515 Background: AK112 is a tetrameric bispecific antibody targeting PD-1 and VEGF-A. Published data suggests that the combination of anti-VEGF-A with immune checkpoint inhibitor (ICI) therapy produces complementary and synergistic antitumor effects. Given the strong correlation between VEGF-A and PD-1 expression in the tumor microenvironment, it is postulated that the simultaneous blockade of these 2 targets by AK112 as a single agent might achieve higher target binding specificity and produce enhanced antitumor activity, with an improved safety profile, compared to the co-administration of anti-PD-(L)1 and anti-VEGF therapies. Here, we present preliminary safety and efficacy data from a dose escalation study of AK112. Methods: A multicenter, phase I, open-label dose escalation and expansion study in advanced solid tumors that are resistant/refractory to standard therapies, began in December 2019 to determine the safety and efficacy of AK112 (0.3 mg/kg to 30 mg/kg) administered IV every 2 weeks (Q2W) using an accelerated titration followed by 3+3+3 dose escalation design. Selected dose escalation cohorts were expanded to a maximum of 18 subjects with selected solid tumor types for further evaluation of safety, pharmacokinetics (PK), pharmacodynamics (PD), immunogenicity, and anti-tumor activity. Pts with prior exposure to ICI were eligible. PD studies examined serum VEGF levels and PD-1 receptor occupancy (RO) on circulating T-cells as an indication of target engagement. Results: As of 13 Jan 2021, 29 pts, median age 60 years [30-76], have received AK112 at doses of 0.3 mg/kg (n = 1), 1.0 mg/kg (n = 3), 3.0 mg/kg (n = 3), 10.0 mg/kg (n = 13), 20.0 mg/kg (n = 8), and 30.0 mg/kg (n = 1) Q2W. Treatment-related adverse events (TRAEs) occurred in 55.2% of pts. G3 TRAEs occurred in 10.3% [3/29] and treatment-related SAEs occurred in 3.4% [1/29] of pts. There was no G4 TRAE. No DLT occurred. TRAEs leading to treatment discontinuation occurred in 6.9% of pts [2/29]. Most frequent TRAEs were arthralgia (17%), diarrhea (14%), rash (10%), and fatigue (10.3%). Of the 17 evaluable pts treated at doses ≥ 3 mg/kg Q2W, the ORR was 23.5% (4/17) and disease control rate (DCR) was 64.7% (11/17). Among the 4 responders, a responder (endometrial ca) had not received prior ICI or bevacizumab, 2 responders (ovarian ca, mesothelioma) had received prior ICI therapy; and a responder (microsatellite stable colorectal ca) was previously treated with bevacizumab. Conclusions: AK112, up to 20 mg/kg Q2W (inclusive), can be given safely to pts and demonstrated encouraging anti-tumor activity with an ORR of 23.5% when dosed ≥ 3 mg/kg Q2W in a pt population with various solid tumors resistant/relapsed to standard therapies. Enrolment is currently ongoing at 30.0 mg/kg Q2W and in dose escalation cohorts selected for expansion. Updated data, including PK, serum VEGF, and RO will be presented. Clinical trial information: NCT04047290.
136P Phase I dose escalation study of MCLA-145, a bispecific antibody targeting CD137 and PD-L1 in solid tumors
