Hypofractionated Radiation Therapy Plus Palladia for unresectable Canine Mast Cell Tumors


The goal of this study is to determine whether the addition of radiation therapy to Palladia will result in a higher likelihood of tumor shrinkage, and/or a longer duration of improvement.


Mast cell tumor is a common skin tumor of dogs. Current treatment options available for mast cell tumor include various combinations of surgery, chemotherapy drugs such as vinblastine or lomustine, radiation therapy, and the new oral mast cell tumor drug Palladia (toceranib). Palladia is an oral drug which works by inhibiting the function of a protein important for mast cell survival called KIT. Large studies have demonstrated that Palladia can be effective for some canine mast cell tumors. However, most mast cell tumors treated with Palladia do not go away completely, and improvement with Palladia is not permanent. Through this clinical trial, we hypothesize that the combination of Palladia and hypofractionated radiation therapy will be well tolerated and efficacious.

Major Inclusion Criteria

To qualify for enrollment in this study, dogs must:

  • Have histologically or cytologically confirmed, cutaneous/subcutaneous MCT
  • Weigh >5 kgs
  • Have adequate organ function
  • Have not been treated within 2 weeks with chemotherapy
  • Have not received radiation therapy to target lesions

Study Design

Initially your dog will undergo a series of diagnostic tests, which may include blood tests, urinalysis, a fine needle aspirate of the lymph node draining the tumor area, and ultrasound examination of the abdomen. The results of these initial staging tests will determine if your dog is eligible to enter this clinical trial. These tests are part of the routine testing done in mast cell tumor patients, and may be performed even if you decide that your dog will not participate. Blood will be collected for study-related testing. Your dog will be sent home with medications to prevent side effects (Benadryl, pepcid/omeprazole, and prednisone), and Palladia, which will be started 3 days later on a M-W-F schedule. One week following the start of Palladia, your dog will return for a series of 3 or 4 weekly radiation treatments that will be delivered 6-8 hours post Palladia dosing. Regular rechecks will be performed after the completion of radiation therapy.

Client Compensation

  • The study will partially cover the cost of blood work and radiation therapy (up to $1500)
  • Palladia® will be provided free of cost for duration of study and beyond

Client Cost

  • Client is responsible for the cost of initial staging of their dog’s mast cell tumor prior to entering the study
  • The client costs for the entire 16 week treatment period are expected to be approximately $950
  • If your dogs continues on with Palladia at the completion of 16 weeks you are responsible for all blood tests to ensure the Palladia is being tolerated, recheck examinations, and the cost of ancillary medications


Dr. Cheryl London, clinicaltrials [at] cvm [dot] osu [dot] edu, for further information.