A first-in-human phase dose-escalation study of YH002, a recombinant humanized agonistic anti-OX40 IgG1 monoclonal antibody, in patients with advanced solid tumors.

Abstract

e14501 Background: YH002 is a recombinant humanized IgG1 antibody that targets the human OX40 receptor. Preclinical studies have demonstrated the specificity, potency, and anti-cancer efficacy of YH002 in a comprehensive panel. The totality of nonclinical data supports progression of YH002 into clinical studies in adult patients (pts) with advanced solid tumors. Methods: This is an ongoing phase 1 dose-escalation study. Patients with advanced or metastatic refractory solid tumors received YH002 as single agent by IV administration at 0.01 to12.0 mg/kg dose levels every 21 days (Q3W), to evaluate the safety, tolerability and preliminary efficacy. An accelerated titration dose escalation design followed by a traditional 3+3 dose algorithm were utilized to assess dose-limiting toxicity (DLT) and identify MTD and/or RP2D. Tumor assessments were performed per RECIST v1.1 every 9 weeks. Results: By December 31 2020, six patients were enrolled and treated at escalating dose levels of 0.01 (n=1), 0.03 (n=1), 0.1 (n=1) and 0.3mg/kg (n=3), with tumor types including colon cancer, thymic cancer, prostate cancer, colorectal cancer, breast cancer and bladder cancer. Median treatment duration was 10.2 weeks (range 2 – 18). The median age of patients was 67 years old (range 47-78). These patients had progressed after a median of 2 prior lines of available standard therapy. As of data cutoff, no dose limiting toxicities (DLTs), no Grade (G) 3 or above adverse events (AE) or AEs leading to treatment discontinuation were reported. Drug-related adverse events (AEs) were all G1/2 events and occurred in 4 patients, including 8 G1 AEs (pneumonitis, rash, pruritus, arthralgia, myalgia, fatigue, lethargy, rash pruritic) and 3 G2 AEs (1 pneumonitis and 2 fatigue). Out of 5 patients having tumor assessment by RECIST, one pt with Thymic SCC at 0.3 mg/kg had best response of stable disease at week 9, one pt with prostate cancer at 0.1 mg/kg experienced Non-CR/Non-PD, and rest of 3 pts experienced progressive disease. Conclusions: These preliminary results demonstrate that YH002 was safe and tolerable up to 0.3mg/kg. Updated safety and antitumor activity will be presented. Clinical trial information: NCT04353102.