Concurrent treatment with transarterial immunoembolization of hepatic metastases and systemic immune checkpoint inhibitors to overcome immune evasion in patients with metastatic uveal melanoma.

BACKGROUND

Metastatic uveal melanoma (mUM) is an uncommon melanoma subtype, poorly immunogenic with low objective response rates (ORR) to immune checkpoint inhibitors (ICI). Liver-directed therapies (LDT) are commonly used given the strong predilection for hepatic metastases. Transarterial immunoembolization (TAIE) with granulocyte-macrophage colony stimulating factor (GM-CSF) can potentially synergize with concurrent systemic ICI to overcome immune evasion.

METHODS

This single-center, retrospective study includes mUM patients with liver-predominant metastases who received TAIE, with/without concurrent systemic ICI (≤ 3 months before/during TAIE). Endpoints included ORR, progression-free survival (PFS), overall survival (OS), and adverse events (AEs).

RESULTS

Between 2016 and 2023, 18 mUM patients (median age 64 years) received TAIE (median 4 procedures/patient). Fourteen patients (78%) received concurrent ICI. ORR was 17% (3/18), all in patients receiving ICI, with partial responses lasting 4.2, 35 + and 46 months. Disease control rate (stable disease or better) was 56% (10/18). Median time to next systemic therapy or death was 19.5 months (range 1.6- 46). Median PFS and OS from first TAIE treatment were 4.9 months (range 0.7-46) and 35 months (range 1.7- 46). Immune-related AEs (IRAE) during concurrent therapy occurred in seven of 10 patients receiving anti-CTLA-4/PD-1 combination, including hepatitis (n = 5; grade 2 in 1, grade 3 in 4). Four of seven patients resumed anti-PD-1 monotherapy without recurrent IRAE.

CONCLUSIONS

Concurrent LDT with GM-CSF TAIE and ICI, including anti-CTLA-4/PD-1 combination, is feasible, safe, and can lead to sustained clinical benefit in a subset of mUM patients. OS with this combination compares favorably to published outcomes for systemic therapy or LDT alone.