Phase I study of NEROFE and doxorubicin in KRAS-mutated ST2-positive solid tumors.

TPS2667 Background: KRAS-mutated tumors are notoriously difficult to treat clinically with targeted therapies. Recent advances targeting KRAS G12C with sotorasib and adagrasib are encouraging but limited to a small subset of patients. NEROFE is a 14 amino acid peptide which inhibits suppression of tumorigenicity 2 (ST2; member of the interleukin 1 [IL-1] receptor family and IL-33 receptor), a novel immune checkpoint present on tumor cells and tumor-associated macrophages. ST2 blockade with NEROFE has been shown to transform an immunosuppressive tumor microenvironment into an immune-stimulatory microenvironment. NEROFE also has been shown to induce microRNA miR-217 which downregulates KRAS and MAPK1/2 gene expression in preclinical models. When combined with low-dose doxorubicin, NEROFE has a synergistic effect on inducing apoptosis in KRAS-mutated, ST2-positive cell lines and xenograft models. Methods: This is a phase I trial of NEROFE given at 48 mg/m 2 (dose level [DL] -1), 96 mg/m 2 (DL1), 192 mg/m 2 (DL2), or 288 mg/m 2 (DL3) IV weekly with doxorubicin 8 mg/m 2 IV weekly. A standard 3+3 dose escalation/de-escalation is used. The primary objective is to determine the recommended phase II dose. Patients are eligible if they have an advanced solid tumor with a KRAS mutation and ST2-positivity (via immunohistochemistry [IHC], centrally confirmed with pre-screening allowed). Patients must have measurable disease amenable to serial biopsy. Patients must have had progression or intolerance to all standard therapies or must decline available standard therapy. Pharmacokinetic profiles will be analyzed from serial blood draws pre- and 1, 2, 4, 6, and 24 hours post-infusion on cycle 1 day and cycle 2 day 1. Pre- and on-treatment tumor biopsies are mandatory. Correlative studies include IHC for ST2 expression, immune cell infiltration and blood-based analyses of KRAS mRNA, miR-217, and cytokines. Enrollment to DL1 began in Q1 2023 (NCT05661201). Clinical trial information: NCT05661201 .