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The goal of this study is to assess efficacy of Palladia and Vinblastine combined for treatment of canine transitional cell carcinoma and to compare computerized tomography and ultrasound for measurement of tumor response.
Canine transitional cell carcinoma (TCC) of the urinary bladder makes up for 2% of all cancers diagnosed in dogs, and is a common cancer found in certain breeds of dogs – Scottish Terrier, West Highland White terrier, Beagles and Shelties. The location of the cancer within the bladder makes surgery often not an option, and the chance of chemotherapy working in this disease is low – only about 30% of dogs respond to treatment and most only experience stable disease for a period of time. Therefore, new treatments are desperately needed for this disease. Another problem encountered in the treatment of this disease is the fact that because the urinary bladder is an organ that can stretch and contract, measuring bladder tumors accurately and assessing whether treatment is working can be difficult. Ultrasound is currently the method most commonly used to measure TCC although it is very difficult to do so accurately using this technique and measurements are often subjective rather than objective. In human cancer therapy, a CT scan is used to measure human bladder tumors and is the standard practice for determining a response to therapy. Therefore, it is likely that CT scan would be more accurate to measure bladder tumors in dogs. The purpose of this clinical trial is to first determine whether a new combination of drugs to treat TCC is more effective than the currently available therapies, and to also determine whether CT will be more accurate in measuring the TCC before and after treatment.
The two drugs to be combined in this clinical trial are vinblastine, a chemotherapy agent used to treat several different cancers in dogs, and Palladia, an oral drug that works by blocking the signaling of several receptors, including VEGFR2 and PDGFR. Both VEGFR2 and PDGFR are important in permitting the growth of new blood vessels, so Palladia works to slow down or block the growth a blood supply into tumors and prevent them from continuing to grow. There is preliminary evidence that both vinblastine and Palladia may each have some activity against TCC in dogs. A recent pilot study demonstrated that 36% of dogs with TCC given vinblastine had their tumor shrink partially following treatment and another 50% had their tumors stop growing for a period of time. In previous work with Palladia, 3 of 4 dogs treated with drug had their tumors stop growing for a period of time. Vinblastine and Palladia have recently been combined together in a clinical trial to determine how best to use these drugs together in the setting of mast cell cancer. This study identified the dose of vinblastine and Palladia that could be safely combined over multiple treatments. These doses will be used in the current study.
To qualify for enrollment in this study, dogs must have:
A total of 10 dogs will be enrolled on this study. Dogs with a diagnosis of TCC of the urinary bladder will have initial tests performed to determine whether he/she is eligible for the study including bloodwork and chest x-rays. If so, then a baseline ultrasound scan, CT scan and cystoscopy will be performed. Once these have been completed, patients will receive vinblastine once every 2 weeks for a total of 8 treatments, and Palladia orally every Monday, Wednesday and Friday for a total of 16 weeks. All dogs will need to return to the Veterinary Medical Center 1 week following the first treatment, then every 2 weeks for a total of 16 weeks for physical examination, bloodwork and to receive the vinblastine treatments. The abdominal ultrasound will be repeated at weeks 4, 8, 12, and 16 of the study (this does not require anesthesia) and the CT scan will be repeated at weeks 8 and 16 of the study (this does require general anesthesia).