Early Data Show Ongoing Benefit of Bria-IMT in Small Breast Cancer Population

Targeted immunotherapy agent Bria-IMT (SV-BR-1-GM) continued to yield clinical survival benefit in combination with retifanlimab (MGA012) in 11 patients with advanced, metastatic breast cancer who were enrolled in a phase 1/2 trial (NCT03328026) in 2021 or 2022, according to data published in a press release from BriaCell Therapeutics.

"This survival update bodes well for our upcoming pivotal trial, since the FDA has agreed to survival benefits as the primary endpoint," according to the manufacturers of Bria-IMT.

Investigators reported a median progression-free survival (PFS) of 3.5 months, with 1 patient who continued to be progression free. Moreover, 9 patients (82%) remain alive and 7 (64%) experienced either disease control or PFS benefit following treatment with Bria-IMT compared with their most recent prior therapy; this suggests clinical benefit such as improved survival and delayed disease progression.

Patients in this cohort had progressed on a median of 5 prior treatments. Additionally, 4 of 5 patients with grade I/II disease and 6 of 8 patients with hormone receptor–positive disease experienced either disease control or improved PFS.

Moreover, the experimental regimen has so far produced no dose-limiting toxicities.

“This is working, and it’s working well. We had high hopes going into this clinical read-out, and the survival numbers have even exceeded our expectations. …This has a material impact for the patients and their loved ones, especially since some patients may have had only weeks or months to live prior to [this] treatment,” William V. Williams, MD, president and chief executive officer of BriaCell, said in the press release. “This survival update bodes well for our upcoming pivotal trial, since the FDA has agreed to survival benefits as the primary endpoint.”

This ongoing, open-label, double-arm phase 1/2 trial included a total of 12 patients in 2021 and 2022, and this year has enrolled a further 9 for expanded analysis. Patients received the Bria-IMT regimen with combination immunotherapy and underwent an evaluation every 3 weeks.

If Bria-IMT plus retifanlimab proves to be safe with dose-limiting toxicities in less than 30% of patients, an expansion cohort of up to 24 patients will receive treatment. Patients will be randomly assigned to 1 of 2 regimens, each administering the checkpoint inhibitor therapy at different time points.

Investigators seek to assess the safety of the regimen, with the study’s 3 primary end points being incidence of adverse effects (AEs), incidence of laboratory abnormalities, and changes in electrocardiogram QT intervals. Secondary end points include the objective response rate, the incidence of non-progression, and duration of response.

The trial included patients with HER2-positive and estrogen receptor (ER)– or progesterone receptor (PR)­–positive tumors tht were refractory to prior hormonal therapy. Moreover, patients needed to have been treated with at least 2 prior regimens including at least 2 anti-HER2 agents. Patients with HER2-negative and either ER- or PR-positive tumors, meanwhile, needed to have refractory disease and undergone prior treatment with at least 2 chemotherapy-containing regimens.

Patients with HER2-positive and ER- or PR-positive tumors needed to have experienced treatment failure with at least 2 prior regimens including at least 2 anti-HER2 agents. Patients with triple-negative tumors must have exhausted all other available therapies. Patients also needed to have an expected survival of at least 4 months to be eligible for enrollment.

Reference

BriaCell reports positive survival data in advanced metastatic breast cancer. News Release. BriaCell Therapeutics Corp. February 23, 2023. Accessed February 24, 2023. https://yhoo.it/3XZv3wI