Molecular Profiling And Clinical Characteristic Of Malignant Melanoma In Younger Patients.

e22087 Background: Combination of clinical and molecular data has not yet been well established in adolescent and younger adult patients with melanoma Methods: We performed a retrospective analysis of the molecular profiles and clinical outcome of patients diagnosed at the age younger than 40 treated at UCLA during 2010 to 2019. Patient’s molecular profile, characteristics, and treatment outcome were described using descriptive statistic. Kaplan-Meier curve was used for disease-free survival (DFS) and overall survival (OS). Results: 150 patients with a median age of 29 year (12-39) were analyzed. 101 (67.3%) patients had cutaneous melanoma, 49 (32.7%) had localized uveal melanoma. Of those 101, 23.8% had pre-existing benign or congenital nevus. 70/101 (69.3%) was stage I-II, 26/101 (25.7%) stage III and 5/101 (4.9%) stage IV. Of those 37 patients with molecularly characterized tissue, 23 (62%) had BRAF mutation including 17 V600E, 4 V600 unknown codon, 2 G469A, 2 NRAS and 1 NF-1 mutation. 11/37 were BRAF negative. 79.6% of patients who were not tested were stage I. For patients with stage III, 16/26 (61%) received adjuvant immunotherapy, none of adjuvant targeted therapy. At 35.1 months follow-up time, 27/96 (28%) localized cutaneous melanoma experienced relapse. 1-year DFS was 73% in adjuvant vs. 90% in no adjuvant immunotherapy group. Among 49 uveal melanoma patients, the median age was 27 years old. 23/49 (49%) had a T1 tumor, 18/49 (36.7%) T2, 6/49(12.2%) T3, 1/49(2%) T4. At 45 months follow-up time, three (6.1%) patients developed metastasis. 5-year DFS and OS was 90% and 100%, respectively. 45 patients had tissue for gene expression profiling and/or FISH testing. 15/45 (33%) had class IA, 13/45 (28%) had class IB, and 8/45 (17.7%) had class 2. 24 samples were analyzed by FISH: 14 with disomy 3, 5 with complex disomy 3 with gain of chromosome 6 or 8, and 5 with monosomy 3. Conclusions: Similarly to general population, most of younger patients with melanoma are diagnosed with stage I disease. Among patients with stage III melanoma treated with adjuvant immunotherapy 1-year DFS was comparable to the general population. Patients with stage III who did not receive adjuvant therapy had an excellent DFS which confirms that the decision on selecting patients for treatment was appropriate. The prognosis of younger patients with uveal melanoma was much better than predicted by molecular testing, and much better than expected regardless of gene expression profile or cytogenetic testing.