at-13387 and Urinary-Bladder-Neoplasms

AT13387 is a potent second-generation, fragment-derived HSP90 inhibitor. This phase I study investigated the maximum tolerated dose (MTD)/recommended phase II dose (RP2D) and safety, pharmacokinetic, and pharmacodynamic profiles of two AT13387 regimens in a refractory solid tumor population.. Standard 3+3 dose escalation was used. MTD and RP2D determinations were based on the occurrence of dose-limiting toxicities (DLT) and overall toxicity, respectively. Pharmacokinetic parameters were measured after single and multiple doses. AT13387-mediated induction of HSP70 was evaluated in plasma, peripheral blood mononuclear cells, and paired tumor biopsies.. Sixty-two patients were treated with doses ranging from 10 to 120 mg/m(2) twice weekly and 150 to 310 mg/m(2) once weekly (both for 3 weeks every 28 days). One DLT of visual disturbance occurred at 120 mg/m(2), which was considered the MTD and RP2D for the twice-weekly regimen. No formal DLTs occurred in the once-weekly regimen, but multiple moderately severe toxicities, including diarrhea, nausea, vomiting, fatigue, and systemic infusion reactions, led to selection of 260 mg/m(2) as the RP2D. Exposures of AT13387 increased proportionally with dose. Target engagement as measured by HSP70 induction occurred in plasma and tumor biopsy samples. One patient with gastrointestinal stromal tumor (GIST) who had progressive disease on imatinib had a partial response and remained on treatment for 10 months. Twenty-one patients (34%) had stable disease, which lasted >120 days in 7 patients.. AT13387 administered once or twice weekly has an acceptable safety profile and demonstrated evidence of target engagement and preliminary antitumor activity.

Topics: Adult; Aged; Benzamides; Drug-Related Side Effects and Adverse Reactions; Female; Gastrointestinal Stromal Tumors; HSP90 Heat-Shock Proteins; Humans; Imatinib Mesylate; Isoindoles; Leukocytes, Mononuclear; Male; Maximum Tolerated Dose; Middle Aged; Neoplasm Staging; Piperazines; Pyrimidines; Urinary Bladder Neoplasms

Heat shock protein 90 (HSP90) inhibition is an attractive strategy for cancer treatment. Several HSP90 inhibitors have shown promising effects in clinical oncology trials. However, little is known about HSP90 inhibition-mediated bladder cancer therapy. Here, we report a quantitative proteomic study that evaluates alterations in protein expression and histone post-translational modifications (PTMs) in bladder carcinoma in response to HSP90 inhibition. We show that 5 HSP90 inhibitors (AUY922, ganetespib, SNX2112, AT13387, and CUDC305) potently inhibited the proliferation of bladder cancer 5637 cells in a dose- and time-dependent manner. Our proteomic study quantified 518 twofold up-regulated and 811 twofold down-regulated proteins common to both AUY922 and ganetespib treatment. Bioinformatic analyses revealed that those differentially expressed proteins were involved in multiple cellular processes and enzyme-regulated signaling pathways, including chromatin modifications and cell death-associated pathways. Furthermore, quantitative proteome studies identified 14 types of PTMs with 93 marks on the core histones, including 34 novel histone marks of butyrylation, citrullination, 2-hydroxyisobutyrylation, methylation, O-GlcNAcylation, propionylation, and succinylation in AUY922- and ganetespib-treated 5637 cells. Together, this study outlines the association between proteomic changes and histone PTMs in response to HSP90 inhibitor treatment in bladder carcinoma cells, and thus intensifies the understanding of HSP90 inhibition-mediated bladder cancer therapeutics.

Topics: Antineoplastic Agents; Benzamides; Benzodioxoles; Cell Line, Tumor; Cell Proliferation; Cell Survival; Dose-Response Relationship, Drug; Gene Expression Regulation, Neoplastic; Heterocyclic Compounds, 4 or More Rings; Histones; HSP90 Heat-Shock Proteins; Humans; Imidazoles; Isoindoles; Isoxazoles; Protein Processing, Post-Translational; Proteomics; Resorcinols; Triazoles; Urinary Bladder Neoplasms