Elanco’s Varenzin-CA1 is the first drug for the control of nonregenerative anemia associated with chronic kidney disease (CKD) in cats for which the Food and Drug Administration (FDA) has granted conditional approval, the agency announced May 1. Varenzin-CA1 is available only by prescription from a licensed veterinarian.
CKD is a disease that requires day-to-day management in cats, and nonregenerative anemia is a complication that often contributes to death or euthanasia of affected cats because of poor quality of life. Cats with CKD develop nonregenerative anemia when their kidneys produce less of a hormone called erythropoietin, which helps the bone marrow produce red blood cells.
Current treatments available for nonregenerative anemia in cats with CKD include blood transfusion, supplemental iron therapy, and erythropoietin replacement. However, there are no erythropoietin treatments approved for use in cats. Varenzin-CA1 works by helping to increase production of erythropoietin in the kidney, which in turn stimulates the bone marrow to produce more red blood cells.
Tracey Forfa, director of the FDA’s Center for Veterinary Medicine (CVM), said in a statement that this is the first drug for cats under expanded conditional approval, “a pathway to the marketplace that encourages development of innovative treatments and increases the options for treating animals with uncommon conditions, serious or life-threatening diseases, or diseases without existing or adequate therapies.”
Under conditional approval, the FDA has concluded that the drug is safe for its intended purpose and has a reasonable expectation of being effective. This allows cats suffering from the disease to receive the treatment while full effectiveness data is being collected.
The initial conditional approval is valid for one year with the potential for four annual renewals. During this time, the animal drug sponsor must demonstrate active progress toward proving substantial evidence of effectiveness for full approval. If a sponsor does not meet the requirements for substantial evidence of effectiveness at the five-year mark, the product can no longer be marketed.
Expanded conditional approval authority was granted to the FDA in the Animal Drug User Fee Act of 2018 and is intended for drugs that address a serious or life-threatening disease or condition, or an unmet animal or human health need, and for which demonstrating effectiveness would require a complex or particularly difficult study or studies. The expanded conditional approval program will sunset in 2028.
Varenzin-CA1 is a liquid given orally to the cat once daily for up to 28 days. The treatment may be repeated as needed after a minimum seven-day pause.
Before prescribing the drug, the FDA says veterinarians should advise cat owners about possible side effects, which include vomiting, increases in systolic blood pressure and thromboembolism. The agency also encourages cat owners to work with veterinarians to report adverse events or side effects potentially related to the use of any drug, including Varenzin-CA1.
A version of this story appears in the July 2023 print issue of JAVMA.