143P Molecular profiling and treatmentrelated outcomes with chemo-immunotherapy in patients with mucosal melanoma: A 10-year single-centre retrospective study

Primary mucosal melanomas are rare and aggressive malignancies with limited available information as they are excluded from melanoma trials. They are unique as they exhibit a different molecular profile and mutational burden, when compared to cutaneous melanoma. Activity of commonly used regimens is not well defined, and therefore, there is no consensus on the optimal first-line treatment. The study was conducted at the Christian Medical College, Vellore, India, between January 01, 2012, and January 01, 2022. The hospital information system was used to retrieve data which was then analysed using SPSS software. The primary outcome was progression free survival and overall survival. 50 patients with mucosal melanoma were included. The mean age was 52, with 25 (50%) being males. Anatomically, Anorectal melanomas were 39 (78%), 07 (14%) were of the head and neck and 04 (8%) melanomas were of the genital tract. 19 (38%) had no distant metastasis, while 28 (56%) had distant metastasis. Mutation testing done on 31 patients revealed only 1 (3.2%) patient each with Exon 9 of cKIT, Exon 2 of N-RAS and cKIT. 23 patients in the entire cohort underwent surgery and 10 patients adjuvant radiation. Median OS for 23 patients who had surgery was 39 months (7.7 to 70.2 months). The median overall survival for the entire cohort was 26.6 months (12.8 to 40.3 months). Overall survival in 25 patients with metastasis was 14 months (9.8 to 18.1 months), P value=0.01. Toxicity observed were mainly related to chemotherapy and no Immune related adverse events were noted probably due to small sample size. Details of treatment delivered will be presented. Swimmers plot, indicating survival data will be presented. Surgery can achieve cure in patients with non-metastatic mucosal melanoma. Targetable mutations are uncommon, however molecular testing can help differentiate clear cell sarcoma from mucosal melanoma. Duration of response to checkpoint inhibitor is modest and inferior when compared to cutaneous melanoma. Chemo-immunotherapy or Immunotherapy with TKI combination therapy may achieve better outcomes.