Phase I study of AZD0530, an oral potent inhibitor of Src kinase: First demonstration of inhibition of Src activity in human cancers

3520 Background: Agents that specifically inhibit the invasive phenotype of cancers are urgently required. AZD0530 is a potent, orally administered inhibitor of Src that has been shown preclinically to prevent phosphorylation of downstream mediators of motility and invasion, paxillin (Pax) and focal adhesion kinase (FAK), with inhibition of metastasis in vivo. Although Src activation is associated with poor prognosis, inhibition of Src activity in human cancers has never been demonstrated. Methods: Patients with cancer received AZD0530 in dose cohorts of 50 mg to 250 mg daily in this 2-part Phase I study. Paired tumor biopsies were acquired for investigation of Src inhibition. Part A defined MTD, toxicity profile and PK. Part B expanded the 50 mg, 125 mg and 175 mg cohorts to characterize changes in phosphorylation of the Src substrates Pax and FAK by evaluating intensity and localization of staining by IHC. Biopsy samples were assigned as pre- or post-AZD0530 treatment by an independent pathology panel blinded to treatment status, and tested for 80% concordance at a 10% alpha. Markers of bone turnover were collected. Results: There were 81 patients evaluable for safety assessment. The median number of prior therapies was 5 (1–27). Part A: DLTs occurred in 3 patients at 250 mg (leukopenia; septic shock (grd5) with renal failure; asthenia) and in 2 patients at 200 mg (febrile neutropenia; dyspnea). Part B confirmed the 50, 125 and 175 mg doses to be tolerable. The mean duration of AZD0530 treatment was 44 days (6–217); 11 patients were treated for longer than 3 months. The pathology panel found consistent modulation of phosphorylation and/or cellular localization of tumor Pax (P=0.067) and FAK (P=0.002) consequent to AZD0530 therapy. There was a dose response trend for reductions in Pax phosphorylation. Bone biomarker and PK data will be presented. Conclusion: For the first time, biomarkers have confirmed inhibition of Src in human cancers. AZD0530 is well tolerated at doses that demonstrate significant inhibition of Src activity. The trend for dose response changes in biomarkers of Src inhibition indicates that the MTD should be taken forward in further development. AZD0530 has a potential role in the prevention of metastases and invasion. No significant financial relationships to disclose.