In vitro Cytotoxic Activities of the Oral Platinum(IV) Prodrug Oxoplatin and HSP90 Inhibitor Ganetespib against a Panel of Gastric Cancer Cell Lines

An update on the status of HSP90 inhibitors in cancer clinical trials

The evolutionary conserved molecular chaperone heat shock protein 90 (HSP90) plays an indispensable role in tumorigenesis by stabilizing client oncoproteins. Although the functionality of HSP90 is tightly regulated, cancer cells exhibit a unique dependence on this chaperone, leading to its overexpression, which has been associated with poor prognosis in certain malignancies. While various strategies targeting heat shock proteins (HSPs) involved in carcinogenesis have been explored, only inhibition of HSP90 has consistently and effectively resulted in proteasomal degradation of its client proteins. To date, a total of 22 HSP90 inhibitors (HSP90i) have been tested in 186 cancer clinical trials, as reported by clinicaltrials.gov. Among these trials, 60 % have been completed, 10 % are currently active, and 30 % have been suspended, terminated, or withdrawn. HSP90 inhibitors (HSP90i) have been used as single agents or in combination with other drugs for the treatment of various cancer types in clinical trials. Notably, improved clinical outcomes have been observed when HSP90i are used in combination therapies, as they exhibit a synergistic antitumor effect. However, as single agents, HSP90i have shown limited clinical activity due to drug-related toxicity or therapy resistance. Recently, active trials conducted in Japan evaluating TAS-116 (pimitespib) have demonstrated promising results with low toxicity as monotherapy and in combination with the immune checkpoint inhibitor nivolumab. Exploratory biomarker analyses performed in various trials have demonstrated target engagement that suggests the potential for identifying patient populations that may respond favorably to the therapy. In this review, we discuss the advances made in the past 5 years regarding HSP90i and their implications in anticancer therapeutics. Our focus lies in evaluating drug efficacy, prognosis forecast, pharmacodynamic biomarkers, and clinical outcomes reported in published trials. Through this comprehensive review, we aim to shed light on the progress and potential of HSP90i as promising therapeutic agents in cancer treatment.

Diagnostic, clinicopathologic, therapeutic and prognostic value of Plasma Heat Shock Protein 90 levels in patients with advanced Gastrointestinal Carcinoma

Purpose: Heat shock protein 90 (HSP90) is a critical molecular chaperone for protein folding, intracellular disposition and regulation of tumor biological behavior in the extracellular space. HSP90 has received much attention due to its specific effect in gastrointestinal cancer. This clinical study sought to determine whether HSP90 in plasma may serve as a biomarker in patients with advanced gastrointestinal carcinoma.

Methods: Using human plasma samples of advanced gastrointestinal carcinoma, we investigated the specific value of HSP90 in gastrointestinal cancer from a clinical perspective.

Results: In summary, plasma levels of HSP90 were shown to be higher in patients with gastric cancer (GC) or colorectal cancer (CRC) than in controls with benign gastrointestinal diseases. In both GC and CRC patients, HSP90 was significantly associated with live metastasis. Higher HSP90 levels were more frequent in CRC patients with hazardous or harmful alcohol consumption habits. Patients with RAS mutations had higher HSP90 levels in CRC. Compared with Carcinoembryonic Antigen (CEA) and Carbohydrate Antigen 19-9 (CA19-9), HSP90 benefited patients by enhancing diagnostic sensitivity and the Youden index. The levels of HSP90 were inversely associated with short-term efficacy in GC patients who had received fluorouracil/platinum-based advanced first-line treatment. When first-line therapy failed, plasma HSP90 levels in patients with GC were significantly increased. In terms of progression-free survival (PFS), patients with GC or CRC who had low levels of HSP90 were not significantly different from those with high levels of HSP90. Univariate and multivariate analyses demonstrated that HSP90 was not an independent prognostic predictor for GC and CRC patients with PFS. However, RAS mutation was an independent prognostic factor for poor PFS in CRC patients.

Conclusions: Plasma HSP90 levels have potential diagnostic value in advanced gastrointestinal carcinoma and therapeutic predictive value in GC.