Daratumumab monotherapy for patients with relapsed or refractory natural killer/T-cell lymphoma, nasal type: an open-label, single-arm, multicenter, phase 2 study

Background Natural killer/T-cell lymphoma (NKTCL) is a disease with limited treatment options and poor outcomes. Daratumumab monotherapy demonstrated clinical activity in a single-patient case report. We present data from the primary analysis of a phase 2 study of daratumumab monotherapy in relapsed or refractory (R/R) NKTCL. Methods This phase 2 study with Simon's two-stage design evaluated daratumumab in patients with histologically confirmed extranodal NKTCL, nasal type, per WHO classification that was refractory to or relapsed after >= 1 line of chemotherapy, who were not candidates for other treatment modalities. All patients received daratumumab 16 mg/kg intravenously once weekly for Cycles 1 and 2, every other week for Cycles 3 through 6, and every 4 weeks thereafter until progression or unacceptable toxicity; all cycles were 28 days. The primary end point was objective response rate (ORR) based on blinded independent central review per Revised Criteria for Response Assessment of Hodgkin and non-Hodgkin Lymphoma (Lugano classification). Results In total, 32 Asian patients received daratumumab. The ORR was 25.0% (95% confidence interval [CI] 11.5-43.4); all 8 responders had a partial response; and the median duration of response was 55.0 days (95% CI 29-339). At 10.2 months of median follow-up, median progression-free survival (PFS) was 53.0 days (95% CI 43-106); the 4-month PFS rate was 13.0%. Median overall survival (OS) was 141.0 days (95% CI 94-438); the 6-month OS rate was 42.9%. Nineteen (59.4%) patients had grade 3/4 treatment-emergent adverse events (TEAEs); the most common was thrombocytopenia (25.0%; n = 8). TEAEs leading to death occurred in 4 patients (death, respiratory failure, septic shock, and pneumonia); all were unrelated to daratumumab. Conclusions In patients with R/R NKTCL, daratumumab monotherapy was well tolerated with no new safety concerns and achieved an ORR of 25.0%. However, no patients achieved complete response, and duration of response was short. Trial registration ClinicalTrials.gov, NCT02927925. Registered 7 October 2016.

Automated summary

In this study, daratumumab monotherapy showed an overall response rate of 25.0% in patients with relapsed or refractory NKTCL. However, no patients achieved complete response, and the duration of response was short. Adverse events were manageable and there were no new safety concerns identified.