Abstract
2622 Background: Immunotherapy (ICI) has shown limited survival benefit in patients (pts) with advanced HCC and intrahepatic cholangiocarcinoma (ICC). Nelitolimod (SD-101), a Class C toll-like receptor-9 (TLR-9 agonist), depletes MDSCs while broadly stimulating the tumor microenvironment. Given safety challenges with IV infusion and distribution limitations of needle injection, we studied hepatic arterial infusion (HAI) of nelitolimod with Pressure-Enabled Drug Delivery (PEDD) to enhance ICI responsiveness. Methods: Pts with advanced HCC or ICC were enrolled. Nelitolimod was dose-escalated without ICI (Cohort A), with pembrolizumab (Cohort B), or with nivolumab + ipilimumab (Cohort C). Nelitolimod administered with HAI for 2 cycles, with 3 weekly doses per cycle using the TriNav device. Primary endpoints included safety and optimal dose determination. Immune cells were examined in blood and tumor tissue using multiplex IF, flow cytometry, and Nanostring. Results: At data cutoff, 29 pts [70% ICC, 30% HCC] were enrolled, 23 received at least one dose of nelitolimod: 3 in Cohort A (4 mg), 8 in Cohort B (2 and 4 mg) and 12 in Cohort C (2 and 4 mg). Median age was 64.5. Only 1 pt was treatment-naïve; 4, 2L (17%); 5, 3L (22%); 14, > 4L (61%). 26% pts had > 10 liver tumors. 3 pts (13%) experienced serious treatment-related adverse events (AE); 1 pt dose-limiting toxicity. Five pts experienced LFT elevations, most G1 with 2 reported as G3. In cohort A, 1 of 3 evaluable pts had SD as best on-treatment response. In cohort B, 1 of 4 evaluable pts had SD as best on-treatment response, others experienced PD by RECIST 1.1. In cohort C 2 mg, 2 of 5 had SD reported at Day 53. At 4 mg dose in cohort C, 3 of 3 pts had disease control, with one CR in the liver (5L ICC) and 2 SD. Decreases were noted in the target liver lesion (31.3 to 17.5 mm), non-target liver lesion, and extra-hepatic lymph nodes on days 53 and 84 with complete response of target liver lesions and stability of extra hepatic nodal lesions reported on Day 154. Median PFS in the Cohort C 4 mg dose level is >120 days. Median OS for this group has not reached (range 120-170 days). Immune effects in cohort C 4 mg pts included increases in liver tumor CD4+ and CD8+ T cells, along with a decrease in the MDSC:CD8+ T cell ratio. Gene expression changes in cohort C 4 mg pts revealed increased Th1 programming in tumor tissue, with increased interferon, cytokine, TLR, Th1, and lymphocyte activation signals in surrounding normal liver. Changes among blood immune cells included increased IFNg and IL2-R expression, with decreased IL17A and VEGFA. Conclusions: HAI of nelitolimod has been well tolerated and associated with encouraging immunologic activity in HCC and ICC. Clinical and biologic activity in cohort C at 4mg is supportive of further enrollment in this cohort. Clinical trial information: NCT05220722 .
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