NEW YORK – Angle on Friday said it is seeking to engage with BlissBio Biopharmaceutical to develop the antibody-drug conjugate BB-1701 alongside its circulating tumor cell (CTC) assay, following Eisai's decision not to exercise its option for the drug.
In a 2018 deal, Eisai granted BlissBio the exclusive global rights to use the microtubule targeting agent Halaven (eribulin), which Eisai had developed in-house, as a cytotoxic payload in several antibody-drug conjugates. Then, in 2023, the two companies inked a deal to codevelop the ADC BB-1701, comprising Halaven and an anti-HER2 antibody.
Under the terms of that agreement, Eisai was responsible for conducting a Phase II trial of the drug in HER2-mutant or -amplified breast cancer, while BlissBio was eligible for upfront and development milestone payments. In the deal, valued at up to $2 billion, Eisai also gained an option to develop and commercialize BB-1701 globally, except for in greater China.
If Eisai had exercised its option, BlissBio would have received an additional upfront payment plus development and regulatory milestone payments, sales milestone payments, and royalties on revenues. However, in a report to investors on its Q4 2024 earnings, Eisai said it will not exercise this option.
Meanwhile, Angle had a contract with Eisai to test the ability of its Parsortix-based assay to measure HER2 CTCs in a Phase II study of BB-1701. In a statement, Angle said that it has shown that the assay can identify "significant differences in HER2 CTC status and numbers of CTCs and CTC clusters" in a patient at different time points before and after treatment. Although Eisai has decided not to exercise its option to this drug, Angle said it has discussed the possibility of using its Parsortix-based CTC assay in other projects with the company.
In September 2024, BlissBio reported initial results from that Phase II trial showing that among 24 patients with advanced or metastatic HER2-mutant or -amplified cancer previously treated with one or more lines of anti-tumor therapy, 12 patients who received BB-1701 had a partial response and 10 had stable disease. The best overall response rate was 50 percent, and the disease control rate was around 92 percent.
This trial testing the efficacy of BB-1701 is still ongoing, according to Angle. In a statement, the Guildford, UK-based firm said it "is now seeking to engage with BlissBio in order to work with them on the next stage of development of BB-1701," but did not provide further specifics.