Phase l study assessing a two-consecutive-day (QD x 2) dosing schedule of the HSP90 inhibitor, AT13387, in patients with advanced solid tumors.

3087 Background: AT13387, a synthetic, non-ansamycin, small molecule inhibitor of HSP90 (Kd 0.71 nM), binds to the N-terminal ATP-binding site resulting in down-regulation of key oncoproteins (HER2 and ERK). In xenograft models AT13387 produced tumor growth inhibition on a QD x 2 dosing schedule. Objectives: To determine toxicity, MTD, PK, and pharmacodynamic (PD) effect of AT13387 given IV QD x 2, 3 weeks out of 4. Methods: Adult patients (pts) with advanced cancers progressing following standard therapy; ECOG ≤ 2; adequate organ function. One pt cohorts for first three dose levels (DLs, 20, 40, 80 mg/m2), planned 3+3 design at DL 4 (120 mg/m2). PK evaluations on C1D1 and C1D15. Mandatory tumor biopsies in expansion cohort at MTD for HER2+ tumors (baseline, C1D17) to evaluate HSP70 and HSP27 mRNA by RT-PCR; and client protein by IHC and immunoassay. HSP70 in PBMCs as a PD marker (pre-dose, D2, D15, D16) assessed by Western blot; serum markers of cell death, M30 and M65 (baseline and pre-dose C1D16), asse...