FDA Conditionally Approves First Drug for Anemia in Cats

WASHINGTON — The Food and Drug Administration on Monday conditionally approved Varenzin-CA1, the first drug for the control of nonregenerative anemia associated with chronic kidney disease in cats. 

Nonregenerative anemia is a potentially fatal condition in which a cat’s bone marrow is not able to produce enough red blood cells to replace the older or damaged cells.

This inability prevents oxygen from being carried from the lungs to other parts of the body.

Once cats are affiliated with chronic kidney disease, the condition requires day-to-day management, and nonregenerative anemia is a complication that often contributes to death or euthanasia of affected cats due to poor quality of life. 

Cats can develop chronic kidney disease at any age, but it is frequently diagnosed in older cats. It can be triggered by other diseases or malformation of the kidneys, bacterial or viral infections, kidney inflammation, cancers or a build-up of protein in the kidneys. 

Cats with chronic kidney disease develop nonregenerative anemia when their kidneys produce less of a hormone called erythropoietin, which helps the bone marrow produce red blood cells. 

The current treatments available for nonregenerative anemia in cats with chronic kidney disease include blood transfusion, supplemental iron therapy and erythropoietin replacement. However, there are no erythropoietin treatments approved for use in cats. 

Varenzin-CA1 (molidustat oral suspension), developed by Elanco US Inc., is a liquid given by mouth to the cat once daily for up to 28 days. 

It works by helping to increase production of erythropoietin in the kidney, which in turn stimulates the bone marrow to produce more red blood cells.

“Varenzin-CA1 is the first drug to receive conditional approval for use in cats, providing access to a novel medicine for our feline companions suffering from nonregenerative anemia due to CKD,” said Tracey Forfa, director of the FDA’s Center for Veterinary Medicine.

“Additionally, 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,” Forfa said.

The treatment may be repeated as needed after a minimum seven-day pause. Varenzin-CA1 is available only by prescription from a licensed veterinarian, given that professional expertise is required to properly diagnose chronic kidney disease and nonregenerative anemia in cats.

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.

Before prescribing the drug, veterinarians should advise cat owners about possible side effects, which include vomiting, increases in systolic blood pressure and thromboembolism (blood clots). 

The FDA is also encouraging cat owners to work with veterinarians to report adverse events or side effects potentially related to the use of any drug, including Varenzin-CA1.

Dan can be reached at [email protected] and @DanMcCue