BACKGROUND

Until the advent of T cell check point inhibitors standard second-line therapy for patients with metastatic urothelial cancer (mUC) was undefined. Histone deacetylase inhibitors (HDACi) have anti-cancer activity in a variety of tumor models including modulation of apoptosis in bladder cancer cell lines. We evaluated the efficacy and toxicity of the HDACi vorinostat in patients with mUC failing first-line platinum-based therapy either in the adjuvant/neoadjuvant setting or for recurrent/advanced disease.

METHODS

Vorinostat was given orally 200 mg twice daily continuously until progression or unacceptable toxicity. The primary end point was RECIST response rate (RR); a RR > 20% was deemed interesting in a 2-stage design requiring one response in the first 12 patients to proceed to 2nd stage for a total of 37 subjects. CT or MRI scan imaging occurred every 6 weeks.

RESULTS

Fourteen patients were accrued characterized by: median age 66 years (43-84); Caucasian (79%); males (86%); and Karnofsky performance status ≥90 (50%). Accrual was terminated in the first stage as no responses were observed. Best response was stable disease (3 patients). Progression was observed in 8 patients. Two patients came off therapy prior to re-imaging and a 3rd patient died while on treatment and was not assessed for response. Median number of cycles was 2 (range 1-11). Median disease-free survival and overall survival times were 1.1 (0.8, 2.1) & 3.2 (2.1, 14.5) months, respectively. Toxicities were predominantly cytopenias and thrombocytopenic bleeding. Two pts. had grade 5 toxicity unlikely related to treatment. Two pts. had grade 4 and 6 had grade 3 toxicities observed. Two patients with stable disease remained on therapy for 6+ cycles.

CONCLUSIONS

Vorinostat on this dose-schedule had limited efficacy and significant toxicity resulting in a unfavorable risk:benefit ratio in patients with mUC. NCT00363883.