M4 - International Multi-Center Experience of Isolated Limb Infusion for In-Transit Melanoma Metastases in Octogenarian and Nonagenarian Patients

Background: Isolated limb infusion (ILI) is used to treat in-transit melanoma metastases (ITMs) confined to an extremity. Little is known about its safety and efficacy in octogenarian and nonagenarians (ONs; ≥80years old). Patients and

Methods: ONs who underwent ILI for Stage IIIB/IIIC melanoma between 1992-2018 at 9 international centers were included and compared to a younger cohort (<80 years). The cytotoxic drug combination of melphalan +/- actinomycin-D was used.

Results: Of 687 patients, 160 ONs were identified (median age 84; range 80-100). Compared to the younger (n=527; median age 67; range 29-79), ONs were more frequently female (70.0 vs. 56.9%; p=0.003), had more stage IIIB disease (36.3 vs. 46.7%; p=0.02) and underwent upper limb ILIs more frequently (16.9% vs. 9.5%; p=0.009). ONs experienced similar Wieberdink toxicity grades III/IV (25.0% vs. 29.2%; p=0.45); no toxicity-related limb amputations were performed in either group. Overall response rate for ONs was 67.3%, vs. 64.6% for younger (p=0.53). Median in-field progression-free survival was 9 months for both groups (p=0.88). Median distant progression-free survival was 36 vs. 23 months (p=0.16), overall survival was 29 vs. 40 months (p<0.0001), and melanoma-specific survival was 46 vs. 78 months (p=0.0007) for ONs versus younger, respectively.

Conclusion: This first international multi-center study shows that ILI in ONs old is safe and effective with similar response and regional control rates compared to younger patients. Overall and melanoma-specific survival were shorter in ONs, likely reflective of a difference in age-related comorbidity risk and differences in immunological and melanoma biology.