Injecting Immunotherapy Directly Into Mouth Precancers Shrinks Lesions and Spares Surgery
A small phase I trial found nivolumab injected into oral precancers shrank lesions in 85% of patients, offering a non-surgical alternative.
Summary
Researchers at MD Anderson Cancer Center tested injecting a low dose of the immunotherapy drug nivolumab directly into high-risk precancerous oral lesions. In a phase I trial of 29 patients, 85% showed a clinical response, with two-thirds seeing their lesion shrink by at least half. About 21% achieved complete pathologic response, and 82% of treated lesions remained cancer-free at one year. No serious toxicities occurred. This approach could spare patients from repeated oral surgeries that often impair speech and swallowing. A placebo-controlled phase II trial is now underway to confirm these findings.
Detailed Summary
Oral precancerous lesions affect roughly 5% of the general population and carry up to a 36% risk of progressing to cancer. Standard treatment is surgery, but recurrences are common, often requiring multiple procedures that can permanently impair speech, swallowing, and feeding. Researchers are now testing whether immunotherapy injected directly into these lesions can eliminate the need for surgery altogether.
In a phase I trial presented at the American Association for Cancer Research annual meeting, 29 patients with high-risk premalignant oral lesions received intralesional injections of nivolumab, a PD-1 checkpoint inhibitor, every three weeks for four cycles. Doses were just 10 or 20 mg — roughly 2–4% of a standard systemic dose — minimizing exposure while targeting the lesion directly.
Results were striking for an early-phase study. Eighty-five percent of patients experienced a clinical response, and the median lesion area shrank by 60%. About 41% showed histologic downgrading of their lesion, and 21% achieved complete pathologic response. Cancer-free survival at one year was 76% among complete responders, and 82% of all treated lesions remained cancer-free at the one-year mark. Six patients progressed to cancer, but all were caught early and surgically resected.
Safety was favorable. No dose-limiting toxicities occurred, and side effects — fatigue, diarrhea, and rash — were consistent with known immunotherapy profiles at low doses. Notably, only one lesion per patient was treated, yet responses appeared in some untreated lesions, hinting at possible systemic immune activation.
This is an early-phase study with a small sample size, and results must be validated in the ongoing placebo-controlled phase II trial before clinical adoption. Still, for the millions living with oral precancers, this non-surgical immunotherapy approach represents a meaningful potential advance in cancer prevention and quality-of-life preservation.
Key Findings
- 85% of patients with oral precancers responded to direct nivolumab injections in a phase I trial
- Median lesion area shrank by 60%; 21% of patients achieved complete pathologic response
- 82% of treated lesions remained cancer-free at one year with no dose-limiting toxicities
- Doses used were only 2–4% of standard systemic nivolumab, reducing systemic exposure risk
- A placebo-controlled phase II trial is now underway to validate these early findings
Methodology
This is a meeting coverage news report from MedPage Today summarizing a phase I clinical trial presented at AACR 2026. The study enrolled 29 patients at MD Anderson Cancer Center with a median follow-up of 14.5 months. Evidence is preliminary and peer-reviewed publication has not yet been confirmed.
Study Limitations
The trial enrolled only 29 patients, limiting statistical power and generalizability. Results are from a conference presentation and have not yet been peer-reviewed or published in full. Long-term durability of responses and comparative efficacy versus surgery remain unknown pending phase II data.
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