Phase (Ph) I study of pazopanib (P) in combination with vinorelbine (V) in patients with metastatic non-small cell lung cancer (mNSCLC) and breast cancer (mBC).
e13568 Background: V is an established treatment for mNSCLC and mBC, but combination 2nd line chemotherapy has not shown clear benefit for either disease. The anti-VEGF agent bevacizumab improves response rate and progression free survival (PFS) for mNSCLC and mBC. P is a tyrosine kinase inhibitor targeting the VEGF receptors. We hypothesize that because CYP3A4 is inhibited by P and responsible for metabolism of V, there may be synergy between P + V. This is a ph I study testing the combination of P + V in previously treated pts with mNSCLC and mBC. Methods: Pts with Stage IIIB/IV NSCLC or Stage IV mBC with ≤ 2 (lung) or ≤ 3 (breast) prior chemotherapies, no prior VEGF inhibitors, and PS 0-2 were treated with P + V. The objective was to determine the maximum tolerated dose (MTD) of P + V. Dose escalations followed a standard 3+3 design. After 6 pts, the protocol was amended to add an intermittent dosing cohort (2a) to improve tolerability. Response assessment (RA) occurred q 42 days (d) while on study. Pts had weekly toxicity assessments, and PK data was collected on d 1-2 of the first 2 cycles. Results: Eight pts (7 mNSCLC, 1 mBC) were enrolled in 3 of 9 planned cohorts. Pts received a median of 2 cycles. All pts experienced at least 1 grade (gr) 3/4 toxicity. Six dose-limiting toxicities occurred in 4 pts in cohort 2/2a. Five severe adverse events were reported in 4 pts and included thrombocytopenia, neutropenia, abdominal (abd) pain, pneumonia, and hepatotoxicity. Gr 3/4 toxicities were: neutropenia (6), fatigue (2), thrombocytopenia (1), hyperbilirubinemia (1), transaminitis (1), hypertension (1), abd pain (1), and pneumonia (1). 1 pt refused treatment after 1 cycle and had no RA. 5 of 8 pts expired due to progressive disease. No partial responses were noted. Median PFS was 66 d (95% CI 35 to 384 d). Conclusions: Combination of P + V in pre-treated mNSCLC and mBC results in high rates of gr 3/4 toxicities at all dose levels. The trial was suspended due to significant drug-drug interactions before the MTD could be determined. No further study of P in combination with V is warranted in either pt population. Clinical trial information: NCT01060514. [Table: see text]