BioInvent International AB (publ) announced promising Phase 1 data for BI-1206 in combination with MSD's (Merck & Co. Inc., Rahway, NJ, USA) anti-PD-1 therapy KEYTRUDA (pembrolizumab) in heavily pre-treated patients with solid tumors. The data show promising and durable responses in patients who previously failed on anti-PD-1/L1 therapy.

The combination was well-tolerated in this heavily pre-treated population of patients. The data will be presented in a poster at the 2024 ASCO Annual Meeting (ASCO 2024) held in Chicago, Illinois from May 31 to June 4, 2024. The data announced also show that the subcutaneous (SC) administration of BI-1206, being developed in parallel to the IV administration, was well tolerated with no notable injection reactions.

SC administration led to extended target coverage and shows great promise to provide a further extended duration of receptor occupancy with increased tolerability. SC dose escalation is still ongoing. The Phase 1/2a trial is performed in previously treated patients with advanced solid tumors to assess the safety and tolerability of BI-1206 in combination with pembrolizumab at ascending intravenous (IV) and subcutaneous (SC) doses.Dose escalation with IV was completed with no formal maximally tolerated dose, MTD, defined.

The most frequent treatment-emergent adverse events (TEAEs) were infusion-related reactions, thrombocytopenia, and elevated liver enzymes. The events were transient without any clinical consequences and corticosteroid pre-medication, or split dosing reduced the risk and/or intensity of these events. Dose escalation with SC is ongoing, and to date 7 patients have been dosed with no notable safety events related to the combination, including no IRR, thrombocytopenia, or elevated liver enzymes of any grade.

Good target coverage was demonstrated already at entry dose level. In 24 evaluable patients, the combination demonstrated one CR (metastatic melanoma, 3 prior anti-PD-1 treatments including one anti-CTLA-4), one long-lasting PR (uveal melanoma, >24 months) and seven cases of stable disease, including one long-lasting (metastatic melanoma, >24 months). An IV dose level (RP2D) has been selected for signal seeking in the subsequent Phase 2a study, while appropriate dose for use of SC in Phase 2a will be determined after completion of dose escalation.

The Phase 2a part will include three expansion cohorts at the RP2D, each comprising a specific subset of subjects with advanced solid tumors (e.g., NSCLC, melanoma, and other tumors responsive to PD-1/PD-L1 inhibition).