1341PRe-introduction of T-VEC monotherapy in recurrent stage IIIB/C-IVM1a melanoma is effective

Abstract Background Talimogene laherparepvec (T-VEC) is a modified herpes simplex virus, type 1 (HSV-1), which can be administered intralesionally in patients with stage IIIB/C-IVM1a unresectable melanoma. Methods 5 patients with recurrent disease recommenced treatment with T-VEC monotherapy at the Netherlands Cancer Institute after a prior achieved CR. We collected data on response, adverse events (AE) and baseline characteristics. For response evaluation, we used clinical evaluation with photography, 3-monthly PET-CT’s and histological biopsies. Results All 5 patients had in-transit metastases on the lower limb. Median age at baseline was 72.1 years with a median follow-up time of 24.5 months. Histologically proven CR (pCR) was achieved after a median of 8 T-VEC courses on the initial exposure. Of 5 patients, 3 (60%) achieved a histologically and/or PET-CT proven CR again after re-introduction of T-VEC with a median of 3 T-VEC courses and 2 (40%) are still currently on treatment. Duration of response (time between first CR and recurrence) varied between 3.8-14.2 months. No patients developed distant metastases. Grade 1 AE’s occurred in all patients. Mostly, these consisted of fatigue, influenza-like symptoms and injection site pain. PET-CT and histological biopsies proved to be a clinically useful tool to evaluate treatment response for T-VEC monotherapy. Conclusions Response to re-introduction of T-VEC monotherapy in this select patient population is promising. This real world data on re-introduction of T-VEC monotherapy in stage IIIB/C-IVM1a melanoma suggests T-VEC could be a treatment option for chronic disease control in this group of patients. Legal entity responsible for the study The authors. Funding Has not received any funding. Disclosure V. Franke: Advisory / Consultancy, Research grant / Funding (institution): Amgen. M.W.J.M. Wouters: Research grant / Funding (institution): Novartis. W. Van Houdt: Advisory / Consultancy, Research grant / Funding (institution): Amgen. A.C.J. van Akkooi: Advisory / Consultancy, Research grant / Funding (institution): Amgen; Research grant / Funding (institution): novartis; Research grant / Funding (institution): BMS-Merck; Research grant / Funding (institution): Merck-Pfizer. All other authors have declared no conflicts of interest.