Dose Escalation Of Pol6326 In Combination With Eribulin In Her2-Negative Relapsed Metastatic Breast Cancer (Mbca) Patients (Pts).

2548Background: POL6326 is a cyclic peptide and a potent, selective antagonist of the chemokine receptor CXCR4. Evidence suggests that CXCR4 inhibition interferes with the tumor-protective microenvironment and therefore sensitizes tumor cells to chemotherapy. Consequently, POL6326 may enhance the effects of cytoreductive therapy and is being developed as adjunctive cancer treatment. Methods: This open label dose escalation study was conducted in pts with relapsed mBC and with positive CXCR4 expression at tumor site to establish the Maximum Tolerated Dose (MTD) of the combination of POL6326 and eribulin. MTD was defined as the highest dose at which DLT occurs in no more than 1 of 6 pts. Cohorts received eribulin on days 2 and 9, flanked by POL6326 on days 1-3, and 8-10 of 21-day cycles. Pts were treated until disease progression or DLT. Results: 24 pts (median age 53 [38-74]; ECOG PS 1) wereenrolled in 8 cohorts. Eribulin mesilate was administered at 1.4 mg/m2 apart from two cohorts receiving 1.1 mg/m2. PO...