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3536 Background: Polo-like kinase-1 (Plk1), part of a family of highly conserved serine-threonine kinases, has multiple roles in mitotic progression, is over-expressed and also associated with poor prognosis in some tumor types. GSK461364 is a potent and selective ATP-competitive inhibitor of Plk1 (Ki 2.2nM) with demonstrated antiproliferative activity in vitro and in vivo. METHODS: Adult patients (pts) with relapsed/refractory advanced solid tumors with performance status of 0-2 and adequate organ function were eligible. Sequential cohorts of 2-6 patients each received escalating doses of GSK461364 administered as a 4h intravenous infusion (Schedule [Sch] 1: D1,8,15 q28 or Sch 2: D1,2,8,9,15,16 q28). Primary objectives were to determine the maximum tolerated dose (MTD) and pharmacokinetics (PK) of GSK461364. Secondary objectives included preliminary evaluation of anti-tumor activity. RESULTS: 27 pts (20 male, 7 female) were evaluated. Four dose levels, 50mg (n = 2), 100 mg (n = 3), 150 mg (n = 3) and 225 mg (n = 8) were evaluated in Sch 1. Three dose levels, 25 mg (n = 2), 50 mg (n = 2) and 100 mg (n = 7) were evaluated in Sch 2. Dose-limiting toxicities (DLTs) observed were Gr 4 sepsis, in Sch 1 at 225 mg dose, Gr 4 pulmonary embolism (PE) and Gr 4 neutropenia >7d in Sch 2, both at 100 mg dose. Other Sch 1 adverse events (AEs) with a maximum grade ≥3 were fatigue and anemia (both, n = 2), pleuritic pain, pelvic pain, abdominal discomfort, constipation, vomiting, neutropenia, and deep vein thrombosis (all, n = 1). Other Sch 2 AEs with a maximum grade ≥3 were PE, renal failure, thrombocytopenia, and catheter-related infection (all n = 1). The most common adverse events (AEs) regardless of attribution, Sch and dose level were phlebitis (n = 9), fatigue (n = 9), nausea (n = 7), anemia (n = 6), anorexia (n = 6), diarrhea (n = 6), and infusion site reaction (n = 5). Preliminary PK data indicate that AUC and Cmax were proportional across doses; mean values were CLs ∼72-85L/hr, Vss ∼550-1200L and t1/2 ∼11.5hr. Phospho-histone H3, a marker of mitotic arrest, was detected, in circulating tumor cells, 24 hrs after first dose. Stable disease >5m has been observed in 2 esophageal cancer pts. CONCLUSIONS: Dose escalation continues in Sch1, Sch2 has been expanded at 75mg. An MTD has not yet been defined. [Table: see text].


Journal article


J Clin Oncol

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