Dose escalation and expansion (phase Ia/Ib) study of GLS-010, a recombinant fully human antiprogrammed death-1 monoclonal antibody for advanced solid tumors or lymphoma.

Background: GLS-010, a novel engineered fully human immunoglobin G4 monoclonal antibody, can specially block the PD-1/PD-L1/2 axis and reactivate the antitumor immunity.

Aim: This phase Ia/Ib study was carried out to evaluate the safety, recommended phase II dose (R2PD), and primary antitumor effects of GLS-010 in patients with advanced, refractory lymphoma and solid tumors.

Methods: In phase Ia study, patients with refractory solid tumors and lymphoma enrolled and received GLS-010 at a dose of 1, 4, or 10 mg/kg Q2W; 240 mg Q3W or Q2W. The primary objective was to assess the dose-limiting toxicity (DLT). In phase Ib study, doses were expanded in 9 specific tumors to ensure the R2PD and explore the efficacy. Tumor mutation burden level and PD-L1 expression were also assessed with whole-exome sequencing and immunohistochemistry (SP263), respectively.

Results: Up to April 18, 2020, a total of 289 patients (n = 24, phase Ia; n = 265, phase Ib) were enrolled. DLT was not observed in phase Ia part. The T, CL, and V were similar among all dose groups and different tumors. The most common treatment-emergent adverse events (TEAEs) were anemia, leukopenia, elevated alanine aminotransaminase/asparate aminotransferase (ALT/AST), and elevated bilirubin. And hypothyroidism was the most common immune-related adverse event (irAE). The incidence of grade ≥3 TEAE was 39.8%, while grade ≥3 irAE was only 4.5%. Based on safety studies, pharmacokinetics/pharmacodynamics, and preclinical data, 240-mg Q2W was recommended as the expansion dose. The overall objective response rate was 23.6%, with 10 patients achieving complete response. Patients with a high PD-L1 expression level (31.3% Versus. 13.7%, p = 0.012) or t-issue tumor mutation burden level (31.3% Versus. 5.6%, p = 0.009) showed a significantly better response.

Conclusion: GLS-010 showed acceptable safety profile and favorable clinical response. The dose of 240 mg Q2W was an optimal recommended dose as monotherapy.