A Study to Assess CLBR001+ABBV-461 in Subjects With Locally Advanced or Metastatic Breast Cancer

A Phase 1, Open-Label, Dose-Escalation Study Evaluating the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of the Combination of CLBR001, an Engineered Autologous T Cell Product, and ABBV-461, an Antibody-Based Biologic, in Subjects With Locally Advanced or Metastatic Breast Cancer

The goal of this clinical trial is to evaluate CLBR001 and ABBV-461 as a treatment for patients with locally advanced or metastatic breast cancer. The goals are to establish the safety and efficacy of the combination therapy while establishing the optimal biologic doses.

Patients will be administered a single infusion of CLBR001 cells followed by cycles of ABBV-461 with regular assessments of safety and disease response to treatment.

CLBR001 + ABBV-461 is novel switchable CAR-T cell combination therapy comprised of an autologous CAR-T product (CLBR001, the switchable CAR-T cell [sCAR-T]) and ABBV-461 (the "switch" biologic molecule). ABBV-461 acts as an adapter molecule that controls the activity of the CLBR001 CAR-T cell product.

Inclusion Criteria:

• Refractory or relapsed locally advanced or metastatic breast cancer
• Exhaused all standard of care therapy options
• Measurable disease at time of screening in accordance with RECIST v1.1 criteria
• Women or men age ≥18 years of age at time of consent
• ECOG performance status 0 or 1
• Must provide a biopsy sample obtained during the screening period, following the end of the most recent prior line of therapy
• Adequate hematological, renal, and liver function

Exclusion Criteria:

• History of a clinically significant infection within 4 weeks prior to consent
• Active bacterial, viral, and/or fungal infection
• Prior allogeneic stem cell transplant
• Prior lentiviral- or retroviral-based therapy including CAR-T cell therapy
• Prior lymphodepleting or T-cell cytotoxic therapy within 3 months of enrollment
• Subjects receiving attenuated vaccines within 4 weeks of consent or need for live vaccine within 12 months of starting study therapy
• History of significant cardiovascular conditions within the past 6 months
• Subjects with a prior history of or concurrent malignancy whose natural history or treatment has the potential to interfere with either the safety or efficacy assessment of the investigational regimen