Phase II study of enlonstobart (SG001), a novel PD-1 inhibitor in patients with PD-L1 positive recurrent/metastatic cervical cancer

Abstract

Background

Platinum-based chemotherapy with or without bevacizumab is the first-line treatment for patients with recurrent or metastatic cervical cancer (r/mCC), and the treatment options are limited for r/mCC after first-line treatment. Enlonstobart (SG001) is a fully humanized and high-affinity anti-PD-1 immunoglobulin G4 monoclonal antibody. Previous phase Ib study demonstrated that SG001 had a promising efficacy in patients with PD-L1 positive r/mCC.

Methods

In this multicenter, single-arm, open-label, phase II study, eligible patients were ≥ 18 years with PD-L1-positive cervical cancer who had progression on or intolerance to the first-line platinum-based chemotherapy. Patients received SG001 240 mg every two weeks for 24 months or until disease progression, intolerable toxicities, or other study discontinuation criteria were met. The primary endpoint was confirmed objective response rate (ORR) assessed by RECIST version 1.1 by independent review committee.

Results

107 patients were enrolled with median age of 53 years (range 26–72). 64.5 % of patients had a ECOG of 1. After a median follow-up of 14.0 months (range 0.4–21.9), confirmed ORR was 29.0 %, with two complete responses and twenty-nine partial responses. The disease control rate was 54.2 %. Median duration of response was 16.6 months (95 % CI 10.8-NA), median progression free survival was 3.1 months (95 % CI 2.2–6.9). Median overall survival was not reached. 104 patients (97.2 %) experienced at least one treatment emergent adverse events TEAEs, of which 38 patients (35.5 %) had grade 3 or higher TEAEs. The most common treatment-related adverse events were leukopenia (19.6 %), increased aspartate aminotransferase (18.7 %), anemia (17.8 %), increased alanine aminotransferase (15.9 %), hypothyroidism (15.0 %), neutropenia (15.0 %), and hyperthyroidism (11.2 %).

Conclusion

SG001 monotherapy demonstrated durable anti-tumor activity with acceptable safety in patients with PD-L1 positive r/mCC with progression on or intolerance to the first-line platinum-based chemotherapy.

Trial registration

ClinicalTrials.gov (NCT04886700).