Phase III TrilynX Trial Shows Xevinapant Worsens Outcomes in Head and Neck Cancer Patients
核心洞察
The TrilynX phase III trial found that adding xevinapant to standard chemoradiotherapy significantly worsened event-free survival in patients with unresected locally advanced head and neck squamous cell carcinoma.
Patients receiving xevinapant had a median event-free survival of 19.4 months compared to 33.1 months in the placebo group, with higher rates of serious adverse events and treatment discontinuation.
The unexpected poor tolerability and safety profile led to more frequent cisplatin dose reductions, potentially contributing to the inferior efficacy outcomes.
A large international phase III clinical trial has delivered disappointing results for xevinapant, an inhibitor of apoptosis proteins (IAP) inhibitor, showing that adding the experimental drug to standard chemoradiotherapy actually worsened outcomes for patients with unresected locally advanced squamous cell carcinoma of the head and neck.
The TrilynX study, published in the Journal of Clinical Oncology, enrolled 730 patients between September 2020 and February 2023 across multiple international sites. Patients were randomly assigned to receive either xevinapant at 200 mg once daily (n=364) or placebo (n=366) for six cycles, combined with standard chemoradiotherapy consisting of cisplatin at 100 mg/m² every three weeks and intensity-modulated radiation therapy at 70 Gy in 35 fractions.
Primary Endpoint Shows Detrimental Effect
The trial's primary endpoint of event-free survival revealed concerning results. Patients in the xevinapant group had a median event-free survival of just 19.4 months (95% CI: 14.5 months to not estimable) compared to 33.1 months (95% CI: 21.0 months to not estimable) in the control group. This represented a hazard ratio of 1.33 (95% CI: 1.05-1.67, P = 0.9919), indicating significantly worse outcomes with the addition of xevinapant.
Secondary efficacy endpoints similarly favored the control group. Median progression-free survival was 26.8 months in the xevinapant arm versus 33.1 months in the placebo arm (HR = 1.24, 95% CI: 0.97-1.57). Overall survival data showed a concerning trend, with 106 deaths in the xevinapant group compared to 81 in the control group (HR = 1.39, 95% CI: 1.04-1.86), though median overall survival was not reached in either arm at the time of analysis.
Safety Profile Raises Concerns
The safety analysis revealed substantial tolerability issues with xevinapant. Grade ≥3 adverse events occurred in 87.9% of patients receiving xevinapant compared to 80.3% in the placebo group. The most common severe adverse events included anemia (21.4% vs 14.3%) and neutropenia (19.5% vs 19.4%). Notably, grade ≥3 pneumonia occurred more than twice as frequently in the xevinapant group (8.0% vs 3.1%).
Serious adverse events were substantially more common with xevinapant, affecting 53.3% of patients compared to 36.2% in the control group. The poor tolerability led to higher discontinuation rates, with 38.2% of xevinapant patients stopping treatment due to adverse events versus 24.4% in the placebo group. Treatment-emergent adverse events leading to death occurred in 22 patients (6.0%) in the xevinapant group compared to 13 patients (3.7%) in the placebo group.
Treatment Delivery Compromised
The toxicity profile of xevinapant appeared to compromise the delivery of standard therapy components. More patients in the xevinapant arm received suboptimal radiation doses, with 15 patients (4.1%) receiving 50 to <70 Gy compared to 5 patients (1.4%) in the placebo group, and 26 patients (7.1%) receiving ≤50 Gy versus 15 patients (4.2%) in the control arm.
The median cumulative cisplatin dose was also lower in the xevinapant group at 200 mg/m² compared to 275 mg/m² in the placebo group, suggesting that the additional toxicity from xevinapant led to more frequent dose reductions of the backbone chemotherapy agent.
Study Population and Design
The study enrolled patients with a median age of 61 years in the xevinapant group and 60 years in the placebo group. Primary tumor sites included the oropharynx (39.3% vs 43.7%), larynx (31.9% vs 30.9%), and hypopharynx (28.8% vs 25.4%) in the xevinapant and placebo groups, respectively. Disease staging was predominantly stage IVA (53.8% vs 55.7%), with stage III (28.0% vs 24.0%) and stage IVB (18.1% vs 20.2%) patients also enrolled.
Mechanistic Insights and Trial Termination
The investigators noted that TrilynX represented the first randomized phase III study of an IAP inhibitor in any tumor type. They hypothesized that xevinapant's mechanism of predominantly rewiring cell death toward apoptosis, rather than more immunogenic forms like necroptosis or pyroptosis, might have inadvertently reduced the immune-activating effects of chemoradiotherapy.
"Given the outcomes of this interim analysis, it was determined that xevinapant cannot be recommended for use in this indication," the study authors concluded. The TrilynX trial was terminated on June 24, 2024, following the interim analysis results.
The study's corresponding author, Jean Bourhis, MD, of the Radiation Oncology Department at CHUV in Lausanne, Switzerland, emphasized that the unexpected toxicity and detrimental effects observed with xevinapant addition to standard chemoradiotherapy represent a significant setback for this therapeutic approach in head and neck cancer.