826O - A single-arm, multicenter clinical study of radiotherapy combined with toripalimab in stage I/II extranodal NK/T cell lymphoma

Background

The current standard of care for extranodal NK/T cell lymphoma (ENKTL) is L-asparaginase or pegaspargase-based multiagent chemotherapy combined with radiotherapy. However, overall survival was significantly lower in those patients with inadequate response to L-asparaginase-based multiagent chemotherapy.

Methods

In this prospective, single-arm, multicenter, phase II clinical study, patients with stage I/II ENKTL who did not achieve CR after 2-3 cycles of multiagent chemotherapy containing L-asparaginase or pegaspargase were enrolled. Patients received toripalimab (240 mg, d1, Q3w) plus radiotherapy (95% PTV 56 Gy/28f, d1-d5/w), sequentially with or without 2 to 4 cycles chemotherapy. Then patients received toripalimab for 1 year or until disease progression or intolerable toxicity. The primary endpoint was CR rate.

Results

From February 2019 to present, 22 patients were enrolled who have received the response assessment at least once after radiotherapy. All were originated from the upper aerodigestive tract with a median age of 45 years (range 26-64). 14 were male. 17 (77.3%) and 5 (22.7%) patients were Lugano stage I and II, respectively; 81% were primary tumor invasion (PTI). 8/22 patients (36.4%) had PR, 8/22 had (36.4%) SD, 6/22 (27.2) had PD after previous 2-3 cycles chemotherapy. All patients completed the radiotherapy. The ORR was 90.9%, including 17 CR (77.3%), 3 PR (13.6%), 2 PD (9.1%). 8 patients who responded to previous chemotherapy continued 2 cycles of chemotherapy after completion of radiotherapy. Others received toripalimab alone (median dose: 11; range 3-17). Up to date, the median follow-up time was 23 months (range 3-78), the 2-year PFS rate was 81.6%, and all patients survived. The main adverse events during and after radiotherapy were oral mucositis and hypothyroidism. No grade 3 or higher toxicity occurred.

Conclusions

Toripalimab combined with radiotherapy is safe and have promising efficacy for stage I/II ENKTL who have poor response after previous standard chemotherapy.

Clinical trial identification

ChiCTR2100045147.

Editorial acknowledgement

We acknowledge Shanghai Junshi Bioscience for supplying the study drug.

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.