A phase 2 trial shows that sugemalimab has deep, durable antitumor activity and good tolerability among patients with relapsed or refractory (R/R) extranodal natural killer/T-cell lymphoma (ENKTL), according to results of the primary analysis presented at the 2022 ASCO Annual Meeting.

R/R ENKTL is a rare, aggressive non-Hodgkin lymphoma, and after asparaginase-based treatment regimens fail, patients are left with few treatment options. Sugemalimab is an immunoglobulin (Ig)G4 monoclonal antibody targeting programmed death ligand 1 (PD-L1). About 80% of ENKTL tumor cells express PD-L1, making blockade of this ligand an attractive treatment strategy.

The GEMSTONE-201 trial (ClinicalTrials.gov Identifier: NCT03595657) is a multicenter, single-arm, phase 2 trial that recruited 80 patients with histologically confirmed ENKTL who had experienced failure of an asparaginase-based regimen. Patients were treated with 1200 mg intravenous sugemalimab every 3 weeks for up to 24 months. The primary efficacy endpoint was the objective response rate.


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The patients had a median age of 48.0 years (range, 29.0-74.0), 63.8% were male, 67.5% had stage IV disease, and 51.3% had received only 1 previous line of therapy. They were about evenly split between relapsed disease (53.8%) and refractory disease (46.3%).

The median follow-up duration was 13.4 months, and as of the data cutoff, treatment was ongoing in 23 patients.

The objective response rate was 46.2% (P <.0001), with 37.2% of patients having a complete response and 9.0% a partial response. An additional 10.3% of patients had stable disease. At 6 months, 90.8% of patients maintained response and at 12 months, 86.0%.

The overall survival rate at 6, 12, and 24 months was 79.2%, 68.6%, and 54.6%, respectively.

Most patients (96.3%) experienced treatment-emergent adverse events (TEAEs), and 38.8% had grade 3 to 5 events. Overall, 16.3% of patients had treatment-related adverse events of grade 3 to 5, and 6.3% were treatment-related serious adverse events. TEAEs led to treatment discontinuation (12.5%), treatment infusion interruption (5.0%), treatment delay (16.3%), and death (6.3%).

The most common TEAEs were pyrexia (30.0%), white blood cell count decrease (30.0%), aspartate aminotransferase increase (23.8%), neutrophil count decrease (23.8%), and hypothyroidism (21.3%).

“GEMSTONE-201 is the largest registrational study reported to date to evaluate an anti-PD-1/L1 monoclonal antibody in patients with R/R ENKTL,” noted presenting author Huiqiang Huang, MD, PhD, of Sun Yat-sen University Cancer Center in Guangzhou, China. “Sugemalimab has demonstrated deep and durable antitumor activity in R/R ENKTL… Sugemalimab monotherapy was well tolerated and consistent with the long safety profile of sugemalimab in other studies.”

Based on preliminary data from this study, sugemalimab was granted breakthrough therapy designation for adult patients with R/R enktl in 2021. “Sugemalimab could potentially provide a new and effective treatment option for R/R ENKTL,” Dr Huang concluded.

Disclosure: This research was supported by CStone Pharmaceuticals Co., Ltd. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.

Reference

Huang H, Tao R, Yang Y, et al. GEMSTONE-201: Preplanned primary analysis of a multicenter, single-arm, phase 2 study of sugemalimab (suge) in patients (pts) with relapsed or refractory extranodal natural killer/T cell lymphoma (R/R ENKTL). Presented at ASCO 2022; June 3-7, 2022. Abstract 7501.