A Phase 2 Trial of BDC-1001 as Single Agent and in Combination with Pertuzumab in Subjects with Human Epidermal Growth Factor Receptor 2–Positive Metastatic Breast Cancer Previously Treated with Trastuzumab Deruxtecan

Prior treatment

• Central nervous system metastases with the exception of disease that is asymptomatic, clinically stable (without evidence of progression for at least 4 weeks by repeating imaging during study Screening), and has not required steroids for at least 28 days before starting study treatment.
• Any medical condition requiring corticosteroids (> 10 mg daily oral prednisone or equivalent) or other systemic immunosuppressive therapy within 28 days before starting study treatment. Exceptions include inhaled or topical steroids
• Residual toxicity from previous treatment as described in the protocol
• Prior anticancer therapies as described in protocol.
• Received live/attenuated virus vaccine within 28 days before starting study treatment
• Major surgery within 28 days of starting study treatment
• Radiation therapy within 2 weeks of C1D1
• Subject is a lactating mother or pregnant as confirmed by pregnancy tests within 7 days prior to start of study treatment
• Pulmonary disease including idiopathic pulmonary fibrosis, interstitial lung disease, pneumonitis requiring steroids, or symptomatic pleural effusion within 6 months before starting study treatment OR ongoing requirement for supplemental oxygen
• Arterial thrombotic event, stroke, or transient ischemia attack within 6 months before starting study treatment
• Bleeding diathesis or uncontrolled bleeding within 7 days before starting study treatment
• Bone marrow transplant or solid organ transplant

Other illness

• Malignancy within 2 years before starting study treatment other than the disease under study. Exceptions include indolent or definitively treated disease not expected to require treatment during the study, affect the safety of subjects, or affect the endpoints of the trial
• History of severe hypersensitivity to any ingredient of BDC-1001 or pertuzumab
• Cardiac disease as described in the protocol.
• Any condition that, in the opinion of the Investigator, would interfere with evaluation of BDC-1001 and pertuzumab or interpretation of the subject’s safety or study results
• Hepatic disease resulting in symptomatic ascites, encephalopathy, coagulopathy, esophageal/gastric varices, or persistent jaundice
• Infection included in the protocol.
• Autoimmune disease requiring systemic disease-modifying or immunosuppressive therapy within 2 years before starting study treatment. Exceptions include disease managed with only replacement therapies (eg, thyroxine, etc.)

Other

• Actively enrolled in another clinical study, unless it is an observational (noninterventional) clinical study or the follow-up component of an interventional study
• Subject is unwilling or unable to follow protocol requirements.
• Uncontrolled pleural effusion, pericardial effusion, or recurrent ascites drainage.

• Be able to understand and sign the informed consent form.
• Adequate organ function defined as per protocol.
• Women of childbearing potential should agree not to donate eggs and must use a highly effective contraceptive measure (a method that can achieve a failure rate of less than 1% per year) during treatment and until 7 months after the end treatment. Highly effective, alternative non-hormonal contraceptive measures are preferred.
• Potent men that are partners of women of childbearing potential must be willing to use condoms in combination with a second highly effective method of female contraception (as above) during the study and agree not to donate sperm from Screening through 7 months after completion of study. A male partner will be considered as potent unless surgically sterilized (with documentation of sterility).
• Be age 18 years or older at the time of informed consent.
• All subjects must agree to have a biopsy prior to enrollment. If, in the judgement of the Investigator, a biopsy is not safely accessible or clinically feasible an archival tumor tissue must be submitted in lieu of a freshly collected specimen.
• Histologically confirmed adenocarcinoma of the breast that is HER2+ (per 2018 ASCO/CAP HER2 testing guidelines) by Clinical Laboratory Improvement Amendments (CLIA) certified laboratory assessment
• Have received 2 or more prior lines of anti- human epidermal growth factor receptor 2 (HER2)-directed therapies, at least 1 of them is in the metastatic setting and 1 of the prior therapies needs to be trastuzumab deruxtecan (ENHERTU®). Prior neo-adjuvant or adjuvant therapy that resulted in relapse within 12 months of completion of therapy will be considered a line of treatment for metastatic disease
• Have experienced disease progression on or been otherwise unsuitable for (eg, did not tolerate) the most recent therapy
• Have measurable disease according to Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST v1.1) criteria
• Have Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0 or 1
• Have expected life expectancy of greater than 12 weeks per the Investigator