Boehringer Ingelheim and OSE Immunotherapeutics Present Phase 1 Results with First-in-Class SIRPα Inhibitor BI 765063 in Advanced Solid Tumors at ESMO 2021

Regulatory News:

OSE Immunotherapeutics SA (Paris:OSE) (ISIN: FR0012127173; Mnemo: OSE) today announces that promising data from dose escalation Phase 1 of selective SIRPα inhibitor BI 765063 in patients with advanced solid tumors (Poster 983P) have been presented ⁽¹⁾ at the 2021 European Society for Medical Oncology (ESMO) Virtual Conference held on September 16 – 21, 2021.

Alexis Peyroles, CEO of OSE Immunotherapeutics commented: “ The data presented at ASCO in June and now at ESMO are very interesting as they show early evidence of clinical efficacy of BI 765063 combined with anti-PD-1 BI 754091 in patients with MSS tumors for which anti-PD-1 in monotherapy have shown limited activity and whose medical need is very strong. Based on these Phase 1 escalation dose promising results, we look forward advancing the trial’s expansion phase to confirm the potential of a combination approach as a relevant therapeutic strategy in solid tumors.”

The dose escalation part (Step 1) of the Phase 1 trial evaluating BI 765063 alone and in combination with BI 754091 (ezabenlimab) in advanced solid tumors has been completed.

As of June 2021, a total of 18 patients have been treated (with 16 evaluable for efficacy).

Presentation Highlights:

• The combination of anti-SIRPα BI 765063 with BI745091 was well tolerated with no dose-limiting toxicities (DLTs) and the maximum tolerated dose (MTD) not reached.
• Promising early efficacy was observed with three partial responses (PR) in patients with microsatellite stable (MSS) advanced endometrium or colorectal cancer.
• The recommended Phase 2 dose and dosing schedule of BI 765063 was determined as 24 mg/kg with full receptor occupancy using a once every three weeks dosing schedule.

The trial is currently recruiting MSS advanced colorectal and advanced endometrium cancer patients in the expansion Phase 1 trial (Step 2).

Micro Satellite Instable (MSI) tumors can be effectively treated with immune checkpoint inhibitors alone. However, Micro Satellite Stable (MSS) colorectal and endometrial cancers represent the majority of these cancer patients where monotherapy with immune checkpoint inhibitors has limited benefit ⁽²⁾, highlighting the need for effective newcombination therapies such as BI 765063 and BI 754091 for these patients.

The previous data presented at the 2021 ASCO meeting indicated that BI 765063 was well tolerated and showed monotherapy activity in heavily pre-treated solid tumor patients. In particular, a durable partial response was observed in an advanced hepatocellular carcinoma (HCC) patient (data presented at the ASCO 2021).