Safety and efficacy of trifluridine/tipiracil +/− bevacizumab plus XB2001 (anti-IL-1α antibody): a single-center phase 1 trial

In the tumour microenvironment, IL-1α promotes neoangiogenesis, matrix remodelling, tumour proliferation, chemoresistance, and metastases. Highly expressed in human colorectal cancers, IL-1α is associated with poor prognosis. XB2001, a fully human monoclonal antibody neutralizing IL-1α, was evaluated for safety and preliminary efficacy with trifluridine/tipiracil (FTD/TPI) and bevacizumab in metastatic colorectal cancer patients previously treated with oxaliplatin- and irinotecan-based chemotherapies. This single institution, phase 1 study used a 3 + 3 design to assess XB2001 at doses of 250 mg, 500 mg and 1000 mg every 14 days, associated with FTD/TPI 35 mg/m² (days 1-5 and 8-12, every 28 days) (NCT05201352). The Maximum Tolerated Dose of XB2001 + FTD/TPI was then associated in combination with bevacizumab (5 mg/kg, days 1 and 15). Safety, efficacy, pharmacokinetics and pharmacodynamics were assessed. Seventeen patients (median age: 67.4 years) were enroled. No patient exhibited dose-limiting toxicity at any dose. The most common treatment-related adverse events (TRAE) of any grade (G) were diarrhoea (35.3%), nausea (47.1%) and anaemia (35.3%). G3-4 TRAE were neutropenia (17.6%) hypertension and infection (5.9% each). The RP2D (recommended phase 2 dose) of XB2001 was 1000 mg. The disease control rate was 76%, with 23% of patients achieving an objective response, including one complete response. Response and longer progression-free survival were associated with a decrease in serum IL-6 levels during therapy. High intratumoral IL-1α expression at baseline and CD8/PD-L1 infiltration are associated with a better progression-free survival. The combination of XB2001 with FTD/TPI and bevacizumab is feasible and safe, and showed encouraging clinical activity in chemotherapy-resistant mCRC.