Intralesional Immunotherapy Effective Against Precancerous Oral Lesions, Suggests Study
USA: Researchers have found in a new study that direct injection of immunotherapy into precancerous oral lesions led to an average 60% reduction in lesion size, with over 80% remaining cancer-free at one year. Importantly, no dose-limiting or systemic immune-related toxicities were observed. This approach may reduce the risk of progression to cancer and help some patients avoid major, potentially debilitating surgery.
The findings were presented at the American Association for Cancer Research Annual Meeting 2026, where investigators explored a localized treatment strategy using nivolumab, an immune checkpoint inhibitor. Precancerous oral lesions are relatively common and can carry a substantial risk of transforming into malignancy, yet current management often relies on repeated surgical excision. As noted by lead researcher Moran Amit from The University of Texas MD Anderson Cancer Center, such procedures can significantly impair speech, swallowing, and overall quality of life, particularly in patients with recurrent or multiple lesions.
To address this challenge, the study evaluated intralesional administration of nivolumab at a fraction of the standard systemic dose. A total of 29 patients with high-risk premalignant oral lesions received injections every three weeks for four cycles. Only one lesion per patient was treated to assess whether the effect remained localized. After a median follow-up of 14.5 months, 85% of participants showed a clinical response, defined as a reduction in lesion size, with nearly two-thirds experiencing reductions greater than 50%.
The following were the key findings:
- Histological improvement was seen in 41% of patients with downgraded disease severity.
- Some patients achieved a complete pathological response with no detectable dysplasia.
- Patients without lesion progression did not require surgical removal during follow-up.
- Cases that progressed to cancer were identified early and managed surgically.
- Treatment was generally well tolerated.
- Most adverse events were mild and transient, including fatigue, diarrhea, and injection-site reactions.
- Systemic drug exposure was significantly lower than with intravenous administration.
- Reduced systemic exposure lowered the risk of severe immune-related side effects.
- Immune activation was confined to treated lesions.
- Increased infiltration of key immune cells supported a localized, targeted mechanism.
The researchers emphasized that these findings highlight the potential of localized immunotherapy to preserve organ function while effectively managing disease.
However, the authors acknowledged limitations, including the small sample size, short follow-up duration, and single-arm design, which limit definitive conclusions about long-term outcomes. Larger randomized trials will be necessary to validate these results.
Overall, the study suggests that intralesional immunotherapy could represent a promising, less invasive strategy for managing precancerous oral lesions, with potential applications in other early-stage or premalignant conditions.
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