Neoadjuvant cytoreductive treatment with BRAF/MEK inhibition of prior unresectable regionally advanced melanoma to allow complete surgical resection: REDUCTOR trial.

Abstract

9587 Background: The aim of this study is to evaluate the potency of short-term neoadjuvant cytoreductive therapy with dabrafenib and trametinib (BRAF and MEK inhibitor respectively) to allow radical surgical resection in patients with unresectable BRAF-mutated, locally advanced stage III or oligometastatic stage IV melanoma. Methods: A total of 25 patients with BRAF-mutated, unresectable locally advanced stage III or oligometastatic stage IV (≤3 metastases) melanoma will be treated with dabrafenib and trametinib for 8 weeks. Response evaluation by positron emission tomography/computed tomography (PET/CT) will occur at 2 and 8 weeks. If sufficient downsizing occurs, surgical resection will be performed. Biopsies for translational research will be taken at baseline and 2 weeks. The dissection specimen will be stored at 8 weeks. Results: Currently 20 patients have been included. Of these, 2 patients showed PD upon treatment and did not proceed to surgery. In 17/18 (94%) patients resection was possible after neoadjuvant treatment, of which 16 (94%) were R0 resections. Median follow-up time is 28 months with a median recurrence free survival of 9 months in patients undergoing surgery. The 1-year overall survival (OS) was 94% and 2-year OS 82%. Median OS was not reached. Metabolic response rates (RR) on PET/CT at 8 weeks were: 4 (20%) CR, 14 (70%) PR, 0 (0%) SD, 2 (10%) PD. Pathologic RR differed: 7 (35%) CR, 7 (35%) PR, 3 (15%) SD, 0 (0%) PD and in 3 patients (15%) no pathologic response was measured, since no resection was performed. Most patients (85%) experienced any toxicity, of which 50% was grade 1, 20% grade 2 and 3 patients (15%) experienced grade 3 toxicity. The most common reported toxicity was fever. Conclusions: Neoadjuvant dabrafenib and trametinib shows to be a potent cytoreductive treatment, allowing radical resection of metastases in 16/20 (80%) patients with prior unresectable locally advanced melanoma. Patients with no recurrence remained disease-free for a prolonged period of time. If there was recurrent disease, this usually occurred within months after surgery and this may present an opportunity for further tailored adjuvant therapy. Clinical trial information: NTR4654.