Background: This is an update of an ongoing Phase 1 multicenter combination trial of targeted photoimmunotherapy for patients with recurrent head and neck squamous cell carcinoma that cannot be satisfactorily treated with surgery, radiation or platinum chemotherapy. Photoimmunotherapy uses an antibody (cetuximab) conjugated to a dye (IR700) that can be activated by visible light illumination to induce death of cells expressing the antigen (EGFR) after antibody-antigen binding.
Methods: Five patients with recurrent head and neck SCC who had failed previous definitive treatment were enrolled and underwent treatment with RM-1929, a combination of low dose cetuximab (100mg flat dose IV) and IR700. Infusion of RM-1929 was performed 24 hours prior to light treatment. In the operating room, high intensity visible light was applied to the tumors either on the surface for mucosal/skin disease, or within the tumor via needle-catheter placed fiberoptic light diffuser fibers for submucosal and nodal disease. The treatment time was calculated based on size of treatment area and varied from 4-6 minutes for each lesion treated. Comparisons were made between pre-treatment and 4-week post-treatment cross sectional imaging as well as between pre-treatment and 1, 2, and 4 week post-treatment photodocumentation. A second treatment was performed at 6 weeks for persistent lesions where deemed appropriate.
Results: All five patients tolerated the treatment well with less than 24-hour post-treatment in hospital observations required. Four out of 5 (80%) patients had objective regression of tumor. Three patients showed no progression at one month and two patients had progression at the periphery of the tumor at one month. Four patients underwent a second treatment within 4-6 weeks after the first treatment, while one patient had progression of disease to his spine and is on treatment with palliative chemotherapy. Three patients noted mild rashes, which resolved over the course of 4 weeks without intervention. No other adverse events occurred and no patients reported photosensitivity. Patients noted subjective improvement in dysphagia, otalgia, and pain. No patients had progression of ECOG score.
Conclusion: At this early stage in a phase 1 multicenter clinical trial, targeted photoimmunotherapy with RM-1929 appears to be a safe, well-tolerated option for patients with recurrent head and neck squamous cell carcinoma. Four out of 5 (80%) patients have demonstrated objective clinical response to the treatment.