Toripalimab Combination Therapy Without Concurrent Cisplatin for Nasopharyngeal Carcinoma: The DIAMOND Randomized Clinical Trial.

Importance: With the programmed cell death protein 1 (PD-1) blockade toripalimab, omitting highly toxic concurrent cisplatin may be feasible for nasopharyngeal carcinoma (NPC) without compromising survival.

Objective: To evaluate the efficacy and safety of toripalimab incorporated into induction chemotherapy and radiotherapy, without concurrent cisplatin, for locoregionally advanced NPC.

Design, setting, and participants: Open-label, multicenter, randomized phase 3 clinical trial conducted from August 2021 to July 2022 at 13 hospitals in China, enrolling 532 patients with T4N1M0 or T1-4N2-3M0 NPC; 400 (75.2%) completed the trial per protocol. The final date of follow-up was March 21, 2025.

Interventions: Patients were randomly assigned to either the standard therapy group (n = 266), receiving toripalimab with gemcitabine-cisplatin induction chemotherapy and concurrent cisplatin-radiotherapy (100 mg/m2 triweekly for 2 cycles), or the concurrent cisplatin-sparing group (n = 266), receiving the same regimen without concurrent cisplatin. The 17 cycles of toripalimab (240 mg triweekly) were distributed across the induction, radiotherapy, and adjuvant phases as 3, 3, and 11 cycles, respectively.

Main outcomes and measures: Coprimary end points were failure-free survival (noninferiority margin, 8%) and incidence of all-grade vomiting (superiority design). Secondary end points included overall survival, locoregional recurrence-free survival, distant metastasis-free survival, safety, tumor response, quality of life, and tolerability.

Results: In the 532 patients in the intention-to-treat population (median [IQR] age, 47 [39-54] years; 25.2% women), after a median follow-up of 37.0 (range, 4.0-50.0) months, the concurrent cisplatin-sparing group had a 3-year failure-free survival rate of 88.3% vs 87.6% in the standard therapy group, a difference of 0.7% (lower limit of the 1-sided 95% CI, -3.9%; P = .002 for noninferiority; stratified hazard ratio, 0.92 [95% CI, 0.66-1.79]; log-rank P = .73). In the safety analysis, the incidence of all-grade vomiting was significantly lower in the concurrent cisplatin-sparing group vs the standard therapy group (26.2% [68/260] vs 59.8% [156/261]; difference, 33.6% [1-sided 95% CI, 26.9%-∞]; P < .001). Patient-reported quality of life (participation rate, 87.5%) and tolerability (participation rate, 94.7%) were better in the concurrent cisplatin-sparing group, primarily in gastrointestinal, functional, and global health status.

Conclusions and relevance: In this phase 3 randomized clinical trial, among patients with locoregionally advanced NPC, toripalimab combination therapy without concurrent cisplatin was a feasible treatment with high efficacy in failure-free survival and low toxicity.

Trial registration: ClinicalTrials.gov Identifier: NCT04907370.