Pembrolizumab in Combination With Olaparib in Advanced BRCA-mutated or HDR-defect Breast Cancer

Inclusion Criteria

• Be willing and able to provide written informed consent/assent for the trial
• Be ≥18 years of age on day of signing informed consent
• Advanced BRCA-mutated and/or HDR-defect breast cancer progressing on or after prior therapy for metastatic disease or locally advanced disease; Prior therapy is defined as follows: for triple negative breast cancer - progressing after at least 1 line of any prior chemotherapy; for HER2 positive disease must have progressed after at least two HER2 directed therapies in the metastatic setting including ado-trastuzumab emtansine (T-DM1); for hormone receptor positive disease (ER, PR, or both) must have progressed after a CDK4/CDK6 inhibitor plus hormonal therapy. Patients with progression within 12 months from previous neoadjuvant or adjuvant treatment could be enrolled in the study as 1st line therapy in metastatic setting.
• Measurable disease by RECIST 1.1, with at least one lesion, not previously irradiated, that can be accurately measured at baseline as ≥ 10 mm in the longest diameter (except lymph nodes which must have short axis ≥ 15 mm) with computed tomography (CT) or magnetic resonance imaging (MRI) and which is suitable for accurate repeated measurements. Patients with non-measurable bone metastases in addition to measurable disease are eligible; however patients with non-measurable bone disease as the only site(s) of disease are not eligible.
• ECOG 0 or 1
• Documented BRCA deleterious germline or somatic mutation and/or HDR-defect.
• FFPE tumor tissue available for analysis
• Adequate organ function
• Female subjects: Postmenopausal or evidence of non-childbearing status for women of childbearing potential: negative urine or serum pregnancy test within 28 days of study treatment and confirmed prior to treatment on day 1. Postmenopausal is defined as:
• Amenorrheic for 1 year or more following cessation of exogenous hormonal treatments Luteinizing hormone (LH) and Follicle stimulating hormone (FSH) levels in the post menopausal range for women under 50
• radiation-induced oophorectomy with last menses >1 year ago
• chemotherapy-induced menopause with >1 year interval since last menses
• surgical sterilization (bilateral oophorectomy or hysterectomy)
• Women of childbearing potential and their partners, who are sexually active, must agree to the use of TWO highly effective forms of contraception in combination. This should be started from the signing of the informed consent and continue throughout the period of taking study treatment and for at least 1 month after last dose of study drug(s), or they must totally/truly abstain from any form of sexual intercourse.
• Male patients must use a condom during treatment and for 3 months after the last dose of olaparib when having sexual intercourse with a pregnant woman or with a woman of childbearing potential. Female partners of male patients should also use a highly effective form of contraception if they are of childbearing potential
• Patients must have a life expectancy ≥ 16 weeks

Exclusion Criteria

• Is currently participating or has participated in a study of investigational agent or using an investigational device with 30 days of the first dose of pembrolizumab.
• Has had prior chemotherapy, targeted small molecule therapy, or radiation therapy within 3 weeks prior to study Day 1.
• Subjects must have recovered (i.e., ≤ Grade 1 or at baseline) from any adverse events due to a previously administered agent. Subjects with ≤ Grade 2 neuropathy are an exception to this criterion and may qualify for the study.
• If subject received major surgery, they must have recovered adequately from the toxicity and/or complications from the intervention prior to starting therapy.
• Is receiving systemic steroid therapy within three days prior to the first dose of pembrolizumab or receiving any other form of immunosuppressive medication
• Is expected to require any other form of systemic or localized antineoplastic th