In a Phase 3 trial involving 383 patients, Bristol Myers Squibb and SystImmune announced that izalontamab brengitecan reduced the risk of disease progression or death by 59% in advanced HR+/HER2- breast cancer compared to standard chemotherapy. Patients on the bispecific antibody-drug conjugate achieved median progression-free survival of 8.2 months versus 4.0 months for chemotherapy. The therapy, co-developed under an $8.4 billion agreement, also showed manageable safety across multiple trial indications.
Phase 3 trial efficacy results
- ▪In the PANKU-Breast01 trial, izalontamab brengitecan achieved a confirmed objective response rate of 40.5% with a 6.9-month median duration of response, versus 20.2% and 4.2 months for chemotherapy.
- ▪Overall survival data for izalontamab brengitecan in the PANKU-Breast01 trial was immature at the time of the prespecified interim analysis.
- ▪In the Phase 3 PANKU-Breast01 trial, izalontamab brengitecan reduced the risk of disease progression or death by 59% compared to chemotherapy in patients with advanced HR+/HER2- breast cancer.
- ▪In the 383-patient PANKU-Breast01 study, patients treated with izalontamab brengitecan achieved median progression-free survival of 8.2 months compared to 4.0 months for standard chemotherapy.
PANKU-Breast01 trial details
- ▪The Phase 3 PANKU-Breast01 trial evaluated izalontamab brengitecan in patients with unresectable, advanced HR+/HER2- breast cancer who had failed at least one prior line of chemotherapy.
- ▪In the Phase 3 PANKU-Breast01 trial, the median follow-up duration for progression-free survival was 15.2 months.
Safety and adverse events
- ▪Grade 3 or higher treatment-related adverse events associated with izalontamab brengitecan in the PANKU-Breast01 trial were predominantly hematologic.
- ▪In the PANKU-Breast01 study, 1.6% of patients discontinued izalontamab brengitecan due to adverse events, while two patients developed mild-to-moderate interstitial lung disease.
Mechanism of action
- ▪Upon binding and internalization into tumor cells, izalontamab brengitecan releases its Topo1i payload while simultaneously blocking EGFR and HER3 proliferation and survival signaling.
- ▪Izalontamab brengitecan is an antibody-drug conjugate designed to target both EGFR and HER3 surface proteins to deliver a cytotoxic Topo1i payload directly to cancer cells.
Corporate partnerships and trial sponsorship
- ▪Sichuan Biokin Pharmaceutical sponsors the PANKU-Breast01 trial in Mainland China, while SystImmune and Bristol Myers Squibb co-develop izalontamab brengitecan internationally.
- ▪Bristol Myers Squibb partnered with SystImmune, a subsidiary of Sichuan Biokin Pharmaceutical, in an up to $8.4 billion deal in 2023 to commercialize izalontamab brengitecan outside mainland China.
Broader oncology applications and designations
- ▪The U.S. Food and Drug Administration granted Breakthrough Therapy Designation to izalontamab brengitecan for treating previously treated advanced EGFR-mutated non-small cell lung cancer.
- ▪Izalontamab brengitecan has demonstrated clinical benefit across five distinct tumor indications, including triple-negative breast, EGFR-mutated non-small cell lung, nasopharyngeal, and esophageal cancers.
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