January 3, 2017
The U.S. Food and Drug Administration today announced the conditional approval of Tanovea-CA1 (rabacfosadine for injection), the first new animal drug intended to treat canine lymphoma. Also called lymphosarcoma, lymphoma is a type of cancer in dogs. The active ingredient in Tanovea-CA1 is rabacfosadine, a substance that kills rapidly growing cancer cells.
Lymphoma originates from white blood cells called lymphocytes. These cells are a normal part of the immune system and protect the body from infection, but in lymphoma, they grow abnormally. Although lymphoma can affect virtually any organ in the body, it most commonly starts in organs that function as part of the immune system, such as the lymph nodes, spleen, and bone marrow. The signs of lymphoma in dogs vary depending on which organs are affected. The cause of canine lymphoma is unknown.
Tanovea-CA1 must be prescribed by a licensed veterinarian because professional expertise is needed to correctly diagnose lymphoma in dogs, determine the best treatment, and manage potential side effects. Tanovea-CA1, which comes in a concentrated form, is diluted and given into a vein over 30 minutes. The infusion should be given by or under the supervision of a veterinarian experienced in chemotherapy.
The most common side effects seen in dogs treated with Tanovea-CA1 include decreased white blood cell count, diarrhea, vomiting, decreased or loss of appetite, weight loss, decreased activity level, and skin problems (hair loss, sores, and scabs). Other side effects may occur as well. Veterinarians should advise owners about the possible side effects before using the drug.
Because Tanovea-CA1 is an anti-cancer drug, owners should take extra care when handling and cleaning up after their dog for 5 days after treatment. Veterinarians should discuss these precautions with owners. Tanovea-CA1 has an accompanying client information sheet that veterinarians should review with owners each time their dog is treated with the drug. The client information sheet is for owners to take home with them and summarizes important safety information about Tanovea-CA1.
The “CA1” in Tanovea-CA1 means the drug is conditionally approved. Only animal drugs intended for minor species, such as ferrets or fish, or for minor uses in a major species, such as to treat certain types of cancer in dogs, are eligible for conditional approval. Tanovea-CA1’s conditional approval means that when used according to the label, the drug is safe and has a “reasonable expectation of effectiveness” for treating lymphoma in dogs. The conditional approval allows the drug manufacturer, VetDC, Inc., to legally sell Tanovea-CA1 before proving it meets the “substantial evidence” standard of effectiveness for full approval.
The conditional approval is valid for one year. VetDC, Inc. may ask the FDA to renew the conditional approval annually for up to four more years, for a total of five years of conditional approval. To receive a renewal from the FDA, the company must show active progress toward proving “substantial evidence of effectiveness” for full approval. After collecting the remaining effectiveness data, VetDC, Inc. can submit an application to the agency for possible full approval of Tanovea-CA1.
Tanovea-CA1 must be used as directed on the labeling. Federal law prohibits extra-label (also called “off-label”) use of a conditionally approved animal drug.
The FDA encourages dog owners to work with their veterinarian to report all side effects potentially related to Tanovea-CA1. VetDC, Inc. is required to submit to the FDA all reports of side effects—called adverse drug experience reports—that the company receives. The FDA reviews the reports to identify potential safety and effectiveness concerns that may not have been apparent at the time of conditional approval. The agency conducts this post-marketing monitoring to make sure Tanovea-CA1 continues to meet the required standard of safety and “reasonable expectation of effectiveness” established during the conditional approval process.