Abstract
PURPOSE: Rhenium-skin cancer therapy (SCT) is an innovative, noninvasive radionuclide treatment for nonmelanoma skin cancer (NMSC), which is administered in a single outpatient treatment session. A global, multicenter, single-arm, phase 4 post-marketing clinical study was established to evaluate efficacy, safety, cosmesis, and patient-reported outcomes of OncoBeta rhenium-SCT for NMSC. This report details scheduled 12-month interim results, including toxicity, cosmesis, and patient-reported outcomes. METHODS AND MATERIALS: Eligible patients had biopsy-proven stage I or II basal cell carcinoma or squamous cell carcinoma (SCC) lesions ≤3 mm deep and ≤8 cm(2) in area. Patients were administered rhenium-SCT as a resin applied to adhesive foil affixed to the lesion/s, with a dose of 50 Gy to the deepest point. As per the treatment protocol, efficacy was assessed using modified Response Evaluation Criteria in Solid Tumors criteria after 12 months, with planned primary endpoint measuring complete response scheduled for 24 months. Secondary endpoints included patient-reported quality of life (Skin Cancer Index) treatment comfort, cosmesis (visual assessment scale; 1: poor -10: not visible), and toxicity (CTCAE v5.0). RESULTS: Response rates for 185 treated lesions from 140 patients were 94.1% (174/185) complete response, and 3.2% (6/185) partial response. The remaining lesions were classified as progressive or stable disease in 2.2% (4/185) and 0.5% (1/185), respectively. Quality of life improved by a mean 10.55 (95% CI, 3.79, 17.31) points (100-point scale) from baseline. No patients reported pain or discomfort during treatment. Most patients (88%, 129/147) developed radiation dermatitis as expected, which was predominantly grade 1 or 2 in severity and resolved rapidly. The most common 12-month toxicity in patients was grade 1 hypopigmentation (60.4%; 78/129), while there was no incidence of grade 3 or 4 toxicities at this time. Patient- and clinician-reported cosmesis visual assessment scale outcomes were broadly favorable at 8.1 and 7.7, respectively (10-point scale). CONCLUSIONS: This 12-month interim analysis of EPIC-Skin indicates rhenium-SCT is an effective and well-tolerated treatment for shallow basal cell carcinoma and SCC lesions, yielding favorable safety, cosmesis, and patient-satisfaction outcomes. These outcomes underscore the utility of rhenium-SCT as a single-session, noninvasive treatment for NMSC, offering a safe, effective, and efficient alternative to surgery for patients with functional or cosmetic considerations, and/or comorbidities.