Induction Nivolumab Misses Feasibility Goal in Oropharyngeal Cancer

Administering induction immunotherapy before standard chemoradiation (CRT) in patients with high-risk HPV-positive oropharyngeal cancer proved effective for the majority of patients but narrowly missed the trial’s prespecified feasibility threshold due to cisplatin dosing challenges, according to results from the phase 2 IMMUNEBOOST-HPV trial (NCT03838263).

Investigators reported that the 36-month overall survival rate was 95% (95% CI, 76.4%-99.1%) in the control arm and 90.1% (95% CI, 77.1%-96.1%) in the experimental arm. The stratified HR for death was 2.53 (95% CI, 0.29-21.64).

The study evaluated patients with HPV-positive oropharyngeal cancer who faced an elevated risk of relapse due to either advanced stage disease with T4 or N2/N3 classification or a significant smoking history exceeding 10 pack-years. A total of 62 patients were randomly assigned 1:2 to receive either standard chemoradiation with 70 Gy and cisplatin as the control arm (n = 20) or 2 infusions of nivolumab (Opdivo), followed by the same chemoradiation regimen in the experimental arm (n = 41).

The primary end point focused on feasibility, measured by a composite end point. This required patients to successfully receive both nivolumab infusions on schedule, initiate chemoradiation within a specific window, avoid prolonged radiotherapy breaks, achieve adequate radiotherapy dose delivery, and receive at least 200 mg/m² of cisplatin.

Secondary end points were objective response rate, from 12 to 17 days after the second dose of nivolumab and 3 months post CRT, progression-free survival, and toxicity.

Overall, patients were a median of 61 years old (range, 54-69), and the majority (77%) were male, with an ECOG performance status of 0 (92%) or 1 (8%).

End Points

According to findings published in the Journal of Clinical Oncology, the strategy did not meet its predefined feasibility threshold. The primary end point was not met because 4 of the 41 patients in the experimental arm received less than 200 mg/m² of cisplatin. In the experimental arm, tumor response at 12 to 17 days after the second nivolumab administration was evaluated in 35 of 41 patients. Among them, 2 (6%) had partial response, 28 (80%) had stable disease, and 5 (14%) had disease progression.

Additionally, grade 4/5 acute adverse events (AEs) occurred exclusively in the experimental arm. There were 2 nivolumab-related grade 4 adverse events (hepatic cytolysis and diabetic ketoacidosis), 3 grade 4 AEs related to radiotherapy and/or cisplatin, 2 cancer-related grade 4 AEs, and 1 grade 5 AE (septic shock occurring 2.5 months after random assignment), for which it could not be determined if this was due to nivolumab, cisplatin, or radiotherapy.

Further Exploration

Despite the feasibility challenges, the efficacy data suggested the need for further exploration. With a median follow-up of 37.5 months, the 2-year cumulative incidence of relapse was 7.3% (95% CI, 1.9-18.0) in the experimental arm compared with 15.0% (95% CI, 3.6-34.0) in the control arm. The authors noted that these findings should be interpreted cautiously, as the study was not powered for efficacy.

The authors noted that although induction nivolumab proved deliverable for most patients, the increased rate of high-grade acute toxicities and the specific challenge of delivering full cisplatin dosing underscore the need for careful patient selection and toxicity management if this approach moves forward.

The authors concluded that induction nivolumab before chemoradiation did not meet the feasibility threshold due to reduced cisplatin dosing after toxicity in 10% of patients, though the lower relapse incidence in the experimental arm warrants confirmation in future studies. For community oncologists treating this high-risk population, the trial reinforces the delicate balance between efficacy and tolerability when incorporating novel agents into established curative regimens.

REFERENCE

Mirghani H, Aupérin A, Even C, et al. Induction nivolumab before chemoradiation in high-risk human papillomavirus-driven oropharynx cancers: IMMUNEBOOST-HPV, a multicenter randomized phase II trial. J Clin Oncol. Published online January 22, 2026. doi:10.1200/JCO-25-00835