A phase 2 clinical trial of the heat shock protein 90 (HSP 90) inhibitor ganetespib in patients with refractory advanced esophagogastric cancer

Subsets of esophagogastric (EG) cancers harbor genetic abnormalities, including amplification of HER2, MET, or FGFR2 or mutations in PIK3CA, EGFR, or BRAF. Ganetespib which is a novel triazolone heterocyclic inhibitor of HSP90, is a potentially biologically rational treatment strategy for advanced EG cancers with these gene amplification. This multicenter, single-arm phase 2 trial enrolled patients with histologically confirmed advanced EG cancer with progression on at least one line of systemic therapy. Patients received Ganetespib 200 mg/m2 IV on Days 1, 8, and 15 of a 28-day cycle. The primary endpoint was overall response rate (ORR). Secondary endpoints included: Progression Free Survival (PFS); to correlate the presence of HSP clients with ORR and PFS; evaluating the safety, tolerability and adverse events profile. In this study 26 eligible patients mainly: male 77%, median age 64 years were enrolled. The most common drug-related adverse events were diarrhea (77%), fatigue (65%), elevated ALKP (42%), and elevated AST (38%). The most common grade 3/4 AEs included: leucopenia (12%), fatigue (12%), diarrhea (8%), and elevated ALKP (8%). The ORR of 4% reflects the single patient of 26 who had a complete response and stayed on treatment for more than seventy (70) months. Median PFS and OS was 61 days (2.0 months), 94 days (3.1 months) respectively. Ganetespib showed manageable toxicity. While the study was terminated early due to insufficient evidence of single-agent activity, the durable CR and 2 minor responses suggest that there may be a subset of EG patients who could benefit from this drug.