What question did this study set out to answer?

This research aims to evaluate the safety and efficacy of BC1, an immunotherapy for metastatic breast cancer.

May 30, 2026

Cell-based second-generation immunotherapy BC1 in metastatic breast cancer.

Key Points

This research aims to evaluate the safety and efficacy of BC1, an immunotherapy for metastatic breast cancer.
Phase 1/2a trial at a single site targeting metastatic breast cancer patients.
Intradermal administration of BC1 in escalating doses of 20, 40, or 60 million cells every two weeks, with combination therapy in Phase 1 Part 2.
Expanded access program with patient monitoring for adverse events and survival.
Median follow-up of 3 months with no dose-limiting toxicities reported among participants.
One patient achieved 12 months of disease control after treatment with BC1 and other supportive therapies.
29% of patients experienced adverse events, with none classified as serious.

Abstract

e13083 Background: BC1 (BC-OTS-001; BriaCell Inc) is an allogeneic cancer cell line derived from invasive ductal carcinoma, engineered to secrete GM-CSF; part of the personalized off-the-shelf platform technology currently under development, which builds on the clinical and scientific observations from Bria-IMT (Bria-ABC trial). Intradermal administration of BC1 targets dendritic cell uptake and lymph node trafficking for T-cell priming against tumor antigens. Methods: Descriptive analysis of a single-site Phase 1/2a and expanded access program in metastatic, locally recurrent unresectable, or refractory MBC (HER2+, HR+, TNBC), ECOG ≤2 and brain metastases allowed. Primary endpoint: safety/tolerability dose optimization. Secondary and exploratory endpoints: tumor response, PFS, OS, HLA match, delayed-type hypersensitivity (DTH), time to subsequent therapy, and PFS2. Phase 1/Part 1: intradermal monotherapy dose escalation of 20, 40, or 60 x10 6 cells q2wk x3 at 4 injection sites (upper back and thighs). Escalation proceeds if ≤1 of 3 patients experiences a dose limiting toxicity (DLT) (≥ grade 3 possibly related AE within 4 wks); Phase 1/Part 2: combination with tislelizumab (BeOne Medicines Ltd.) ± adjuncts. Phase 2 expansion: up to 9 subjects at optimal regimen. Expanded access program (EAP) allowed protocol-similar treatment. Adverse events per CTCAE v5.0. Subjects followed for PFS2 and survival q3mo up to 2 years. Results: As of abstract submission, there are 5 Phase 1/2a and 3 EAP participants. Using evaluable subjects with available data; median age 64; 43% HER2-/HR+, 43% TNBC, 14% HER2+; median prior lines 4; 43% DTH+, 29% DTH-, and 29% not yet reported. 4 patients received BC1 monotherapy @20 x10 6 cells (one Phase 1 pt @20M received 17 cycles/12 mo with CR of lung lesion, stable bony lesions and no new lesions reported); one @40M ×4 cycles; 1@60M ×1 cycle; another @60M ×3 cycles. Phase 1 Part 2: one patient received BC1 @20M + tislelizumab with cyclophosphamide 300 mg/m² day −2/−3 and peginterferon 18 μg day 0 q3wk. EAP exposure: @20M ×4 cycles (N = 2), one patient unknown. TEAEs overall and ≥ grade 3 both reported at 29%; there were no DLTs. Median follow up 3 mo. Conclusions: Dose escalation from 20M to 60M and combination with CPI showed tolerable intradermal BC1 and potential clinical benefit in refractory MBC. One patient received 17 cycles with 12 mo of disease control. Expansion cohorts will assess HLA match, DTH, dose optimization, and combination activity. Based on very early preliminary data, BC1 is a potential new option for late stage cancer patients with minimal toxicity and potential home administration as a single agent. The current optimal induction schedule for further evaluation is: BC1 @20M q2wk ×3 + CPI C1D1, then BC1 + CPI q3wk without adjuncts until progression/toxicity. Clinical trial information: NCT06471673 .

Bookmark

Cell-based second-generation immunotherapy BC1 in metastatic breast cancer.

Key Points

Abstract

Cite This Study