Neoadjuvant immunotherapy for clinical stage III melanoma: A community cancer center’s experience.

e21561 Background: Several randomized clinical trials have demonstrated enhanced oncologic outcomes with neoadjuvant immunotherapy (IO) for resectable, clinical stage III cutaneous melanoma. Here we report our community cancer center’s experience with neoadjuvant IO in this patient population. Methods: We used our hospital-based cancer registry to retrospectively analyze cutaneous melanoma patients presenting with resectable, macroscopic clinical stage III disease diagnosed between the years 2018 – 2024. Patients had at least one biopsy proven lymph node metastasis +/- up to 3 in-transit lesions. Those with prior systemic treatment or radiation were excluded. Inclusion criteria required patients to be treated with neoadjuvant IO followed by surgery with lymph node resection. Standardized pathological assessment of metastatic melanoma specimens following neoadjuvant IO was utilized. Adjuvant therapy was at physician discretion. Primary endpoints were event-free survival, pathological response and recurrence-free survival rates based on the pathological response. Results: A total of 44 patients met the inclusion criteria. Two cycles of ipilimumab 1 mg/kg and nivolumab 3 mg/kg were given in 68% of patients. Event-free survival of all patients was 84% and median follow-up was 16 months. Percent of patients with a major pathological response (mPR; ≤10% viable tumor) was 67%, partial pathological response (pPR; >10 to ≤50% viable tumor) was 5% and pathological non-response (pNR; >50% viable tumor) was 29%. Two patients did not proceed to surgery: one progressed on neoadjuvant therapy and the other died due to treatment toxicity. Recurrence-free survival was 96% in the patients with a mPR, 100% with a pPR and 67% for patients with a pNR. Grade 3-4 adverse events within the first 3 months of initiating neoadjuvant IO occurred in 16%. Conclusions: Neoadjuvant IO for resectable, macroscopic clinical stage III melanoma can be safely performed in the community with similar outcomes to published trials. Sequence of therapy and oncologic outcomes. Patients who started neoadjuvant treatment 44 / 44 Neoadjuvant agents Ipilimumab 1 mg/kg + Nivolumab 3 mg/kg: 30 / 44 (68%)Ipilimumab 3 mg/kg + Nivolumab 1 mg/kg: 12 (27%)Pembrolizumab: 2 (5%) Grade 3-4 adverse events during neoadjuvant IO 7 / 44 (16%) Surgery 42 / 44 (95%) 27 lymph node dissection (61%) 15 lymph node excision (34%) 2 no surgery (5%) Median time from initiation of therapy to surgery 2 months (range 1-9 months) Pathological response 28 mPR (67%)2 pPR (5%)12 pNR (29%) Adjuvant treatment 24 / 42 (57%) 18 / 24 Nivolumab (75%) 4 / 24 Pembrolizumab (17%) 2 / 24 BRAF inhibitors (8%) Recurrence-free survival based on pathological response 27 / 28 for mPR (96%) 2 / 2 for pPR (100%) 8 / 12 for pNR (67%) Event-free survival 37 / 44 (84%) Median follow-up 16 months