On August 12, 2023 Bio-Thera Solutions, Ltd (688177:SH), a commercial-stage biopharmaceutical company developing a pipeline of innovative assets and biosimilars, reported positive Phase 1 clinical data for BAT8006 (Folate-Receptor-α-ADC) as part of a presentation of the clinical results of a Phase 1 dose escalation study evaluating the safety and efficacy of BAT8006 at the Bethune Obstetrics and Gynecology Forum in China (Press release, BioThera Solutions, AUG 12, 2023, View Source;adc-and-presents-phase-1-dose-escalation-study-at-the-bethune-obstetrics-and-gynecology-forum-301899142.html [SID1234634299]). BAT8006 is an antibody-drug conjugate (ADC) that is composed of an anti-FRα antibody and an ADC linker-payload combination that is composed of a proprietary cleavable linker that is highly systemically stable and a small molecule topoisomerase I inhibitor.
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As a co-principal investigator of the BAT8006 Phase 1 study that was performed at First Bethune Hospital of Jilin University, Professor Songling Zhang presented dose-escalation results from the study at the Bethune Obstetrics and Gynecology Forum. July 6, 2023 served as the cut-off date for the data presented at the conference. At that time twenty-nine (29) subjects with advanced solid tumors were recruited into four (4) dose cohorts (1.2 mg/kg, 1.8 mg/kg, 2.1 mg/kg and 2.4 mg/kg) in the dose-escalation study. FRα expression was not an eligibility criterion in the study and patients with multiple tumor types, such as ovarian cancer, breast cancer, non-small cell lung cancer (NSCLC) and cervical cancer, were include in the study. Ovarian cancer patients accounted for approximately 60% of the subjects in the study.
All twenty-nine (29) subjects enrolled in the study (regardless of tumor type) had at least one tumor assessment with an Overall Objective Response Rate (ORR) of 31.0% and a Disease Control Rate (DCR) of 86.2%. For the ovarian cancer subgroup fifteen (15) subjects were recruited in the 2.1 mg/kg and 2.4 mg/kg cohorts. Among the twelve (12) ovarian cancer subjects with TPS >25%, the ORR was 58.3% and the DCR was 91.7%. Based on FRα expression epidemiological studies, it is estimated that approximately 75% of ovarian cancer patients have FRα expression >25%. To be noted, most of these ovarian cancer patients had received ＞3 prior anti-tumor therapies that included bevacizumab and PARPi. In addition, two (2) subjects with non-ovarian tumors, including breast cancer and endometrial carcinoma, experienced partial responses.
BAT8006 demonstrated a manageable safety profile with the main treatment related adverse events (TRAEs) being hematological toxicity such as neutropenia, thrombocytopenia, anemia, and gastrointestinal toxicity, including nausea and vomiting. Safety issues such as interstitial lung disease, ocular toxicity and severe hepatotoxicity were not observed in the study and no subjects were withdrawn from the study due to TRAEs.
BAT8006 is currently being evaluated in a Phase 1b study in China with four dose expansion cohorts. Two different patient subgroups are being examined in the Phase 1b study. One patient subgroup consists of FRα-positive ovarian cancer patients while the second patient subgroup consists of FRα-positive patients with non-ovarian cancers. Two different doses of BAT8006 are being evaluated with each patient subgroup. Bio-Thera is also working to expand the BAT8006 clinical program to the United States and Europe.
About BAT8006
FRα is a folic acid-binding protein located on cell membranes that is overexpressed in a variety of solid tumors such as ovarian, lung, breast cancer, etc., but has a limited distribution and a lower level of expression in normal human tissues. Differences in expression levels make FRα an attractive target for ADC drug development. BAT8006 was developed using Bio-Thera’s anti-FRα antibody and Bio-Thera’s proprietary ADC linker-payload combination that includes a systemically stable and cleavable linker and a small molecule topoisomerase I inhibitor. The small molecule topoisomerase I inhibitor payload carried by BAT8006 has a strong cell membrane penetration ability, so when the target cancer cells are killed, the payload can be released and further kill nearby cancer cells, producing a bystander effect which may effectively overcome the heterogeneity of the tumor.
BAT8006 is in the dose optimization and dose expansion studies. More subjects with ovarian cancer, endometrial cancer, NSCLC and breast cancers will be enrolled in the study to further evaluate the exposure-safety and exposure-efficacy response, which will support the final determination of recommended dose in Phase 2.