FDA accepts HBM investee Immunomedics’ breast cancer drug filing
US biotech Immunomedics (Nasdaq:IMMU), a top 10 holding for Swiss-listed HBM Healthcare (2.5% of NAV), has reported that the US FDA has accepted its regulatory application for the antibody-drug conjugate sacituzumab govitecan and granted priority review with an action date of 18 January 2019. The application seeks approval for treatment of metastatic triple-negative breast cancer (mTNBC) in patients who have received at least two prior lines of therapy (third line or later).
The filing is based on data from a single-arm Phase II trial, which showed a 32% response rate based on independent central review, with a median duration of response of 6.7 months and progression-free survival of 5.5 months. As part of the accelerated approval requirement, Immunomedics is conducting a confirmatory Phase III trial called Ascent, in the same setting. Immunomedics plans to start a single-arm Phase II study in second-and first-line TNBC with sacituzumab govitecan as a single agent and, as part of a clinical collaboration with Clovis Oncology, a Phase I/II study of the drug with Clovis’ approved PARP inhibitor Rubraca in mTNBC.
The company is also developing sacituzumab govitecan in metastatic urothelial cancer (mUC), where a pivotal Phase II study, TROPHY U-01, is underway in patients after platinum-based regimen and/or immune checkpoint inhibitor (CPI) therapy and in estrogen receptor-positive metastatic breast cancer (ER+ mBC), where it is discussing potential registration paths with regulators. Sacituzumab govitecan showed an overall response rate of 31% in ER+/HER2– mBC patients with a median duration of response of 7.4 months and progression-free survival of 6.8 months.
Immunomedics has subsequently announced a clinical collaboration with AstraZeneca to evaluate sacituzumab govitecan combined with Imfinzi, AZ’s anti-PD-L1 antibody, in TNBC and urothelial cancer. The two companies will co fund a two-part Phase I/II studies, which will be conducted by AstraZeneca using study drug provided by Immunomedics. If the first part of the study is successful, the trial design allows for rapid transition into randomised Phase II stage.