Clinical trial of vinblastine in dogs with transitional cell carcinoma of the urinary bladder

Transitional cell carcinoma (TCC) of the urinary bladder of dogs can be a difficult cancer to treat, and effective therapies are limited. Vinblastine has been used in humans with TCC and has potent anti-proliferative effects against canine TCC cells in vitro.

To determine the antitumor activity and toxicoses of vinblastine in dogs with urinary bladder TCC.

Animals selected were 28 privately owned dogs that presented to the Purdue University Veterinary Teaching Hospital (PUVTH) with measurable, histologically confirmed TCC.

Prospective clinical trial: The starting vinblastine dosage was 3.0 mg/m(2) i.v. every 2 weeks. Treatment continued until cancer progression or unacceptable toxicoses occurred. Complete evaluations (physical exam, complete blood count [CBC], serum biochemical profile, urinalysis, thoracic radiography, abdominal ultrasound [US]) were performed at 8-week intervals. Urinary tract US with bladder tumor mapping was performed monthly. Toxicoses were graded according to Veterinary Co-Operative Oncology Group (VCOG) criteria.

Tumor responses included 10 (36%) partial remission, 14 (50%) stable disease, and 4 (14%) progressive disease. The median progression free interval was 122 days (range, 28-399 days). The median survival time was 147 days (range, 28-476 days) from 1st vinblastine treatment to death and 299 days (range, 43-921 days) from diagnosis to death. The majority of dogs (27 of 28) did not have clinically relevant adverse effects. Seventeen of 28 (61%) dogs required dosage reductions because of neutropenia.

Vinblastine has antitumor activity against TCC in dogs and can be considered another treatment option for this cancer.