Rintatolimod, Celecoxib and Interferon Alpha 2b With Pembrolizumab For the Treatment of Patients With Metastatic or Unresectable Triple Negative Breast Cancer

PRIMARY OBJECTIVE: I. To evaluate the safety profile of modified CKM (celecoxib, rintatolimod and interferon alpha-2b) regimen (replacement of INTRON \[registered trademark\] A, using alternative source of interferon alpha-2b \[IFNalpha2b\]) combined with pembrolizumab therapy in metastatic triple negative breast cancer patients. SECONDARY OBJECTIVES: I. To evaluate the efficacy of the CKM in combination with pembrolizumab in patients with metastatic triple negative breast cancer (mTNBC) as compared to historic outcomes of pembrolizumab and other anti-PD1/PD-L1 therapies alone, as determined by secondary measures of efficacy including: Ia. Progression-free survival (PFS); Ib. Overall survival (OS); Ic. Overall response rate (ORR) to the combination therapy using Immune Modulated Response Evaluation Criteria in Solid Tumors (iRECIST); Id. Disease control rate (DCR) using iRECIST. EXPLORATORY OBJECTIVES: I. Examine the immune analysis profile of CKM and pembrolizumab combination: Ia. Examine the relationship of infiltrating CD4+ and CD8+ T cells and other immune and genetic markers, and their associated PD-1, CD45RA or CD45RO levels; Ib. Correlate PD-L1 expression within both neoplastic and nonneoplastic stromal elements of the tumor microenvironment to PFS, OS, ORR and adverse events (AEs); Ic. Correlate immune panel results with ORR, PFS, OS and AEs. II. Comparison of response assessment criteria for a prospective analysis: IIa. Response evaluation criteria in solid tumors (RECIST) 1.1 response assessment; IIb. iRECIST response assessment. OUTLINE: This is a phase I dose escalation study of interferon alpha-2b followed by a phase II study. Patients are assigned to 1 of 2 cohorts. COHORT I: Patients receive rintatolimod intravenously (IV), celecoxib orally (PO), interferon alpha-2b IV on days 0, 1, and 2 of week 1 and days 7, 8, and 9 of week 2 on study. Patients receive pembrolizumab IV on day 9 and then every 3 weeks after that for up to 4 doses on study. Patients also undergo computed tomography (CT) scan or magnetic resonance imaging (MRI) at screening and follow-up and undergo blood sample collection during screening and on study. COHORT II: Patients receive rintatolimod IV, celecoxib PO, and interferon alpha-2b IV on days 0, 1, and 2 of week 1 and days 7, 8, and 9 of week 2 on study. Patients receive pembrolizumab IV on day 2 of week 1 and then every 3 weeks beginning in week 4 on study. Patients also undergo CT scan or MRI at screening and follow-up, undergo blood sample collection during screening and on study, and may undergo tumor biopsy at screening and follow-up.