Data from Phase II window study of olaparib alone or with cisplatin or durvalumab in operable Head and Neck Cancer

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Abstract Purpose:We conducted a phase II randomized non-comparative window of opportunity trial to evaluate the inhibition of cellular proliferation and the modulation of immune microenvironment after treatment with Olaparib alone or in combination with Cisplatin or Durvalumab in operable Head and Neck Squamous Cell Carcinoma (HNSCC) patients. Patients and Methods:Forty-one HNSCC patients were randomized to Cisplatin plus Olaparib (Arm A), Olaparib alone (Arm B), no treatment (Arm C) or Durvalumab plus Olaparib (Arm D). The primary endpoint was to evaluate the percentage of patients in each arm that achieved a reduction of at least 25% in Ki67. Secondary endpoints included objective response rate (ORR), safety and pathologic complete response rate (pCR). Paired baseline and resection tumor biopsies and blood samples were evaluated for pre-specified biomarkers. Results:A decrease in Ki67 of at least 25% was observed in 44.8% of treated patients, as measured by quantitative immunofluorescence (QIF). The ORR among treated patients was 12.1%. pCR was observed in 2 patients. Two serious adverse events occurred in 2 patients. PD-L1 levels were significantly higher after treatment in arms (A) and (D). Expression of CD163 and Colony Stimulating Factor 1 Receptor (CSF1R) genes, markers of M2 macrophages, increased significantly posttreatment whereas the expression of CD80 a marker of M1 macrophages decreased. Conclusions:Preoperative Olaparib with Cisplatin or alone or with Durvalumab was safe in the preoperative setting and led to decrease in Ki67 in 44.8% of treated patients. Olaparib-based treatment modulates the tumor microenvironment leading to PD-L1 upregulation and induction of pro-tumor features of macrophages.