Mastocytoma Drug Gets Conditional OK

Kinavet-CA1, marketed as mastinib, has been granted conditional approval from the USDA.

Suggested Veterinary Products

Veterinarians treating dogs suffering from mast cell tumors now have a new drug in their arsenal: Kinavet-CA1 (masitinib).

The U.S. Food and Drug Administration granted conditional approval to AB Science USA’s product in mid-December. The company began shipping orders in January.

“[Kinavet-CA1] gives clinicians a new treatment option which we believe is going to help address a very serious disease,” said Albert Ahn, DVM, president of AB Science USA.

Mast cell tumor, also known as mastocytoma, is the most common cutaneous malignant neoplasm in dogs, accounting for 16 to 21 percent of all skin tumors, Dr. Ahn said.

Specifically, the approved indication is “for the treatment of recurrent or nonresectable Grade II and III cutaneous mast cell tumors in dogs that have not previously received radiotherapy and/or chemotherapy except corticosteroids,” the company reported.

The product is administered orally once a day.

Masitinib has been available through AB Science S.A. in Europe for the treatment of canine mast cell tumors since 2009 under the brand name Masivet. The drug has proven very successful, Ahn said.

“Our European colleagues continue to be amazed at the strong interest and the excellent results with the use of Masivet,” he said, adding that Masivet is identical the U.S. version.
Ahn said he is confident that AB Science can establish masitinib as the reference treatment for canine mast cell tumors in the United States.

Competing Products

Kinavet-CA1 joins Pfizer Animal Health’s Palladia (toceranib phosphate), the first FDA-approved drug specifically for the treatment of cancer in dogs. Palladia, approved in 2009, also belongs to the tyrosine kinase inhibitor class of compounds.

While both drugs are targeted therapies, the mechanisms of action are different, Ahn noted.

AB Science describes Kinavet-CA1 as a tyrosine kinase inhibitor that targets mast cells, important cells for immunity, as well as a limited number of kinases that play key roles in various cancers.

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“This drug is a targeted therapy,” Ahn said. “What this means is that it is specifically targeting receptors on the mast cell tumor in an effort to combat this disease.”

Older generation products or chemotherapeutic agents not only can damage the tumor, they may injure healthy tissue because they are nonspecific, he said. Tyrosine kinase inhibitors, on the other hand, are intended to be very specific in the mode of action.

The move to bring Kinavet-CA1 to market began around 2004 and 2005, according to Ahn.
“A long process, but it certainly reflects the commitment and dedication the AB Science team has had for bringing this type of innovation to animal health,” he said.

Now with the FDA’s conditional approval, veterinarians have a powerful new tool for treating canine mast cell tumors, Ahn said.

More Research Ahead

Conditional approval, as defined by the FDA, means the sponsor can make the drug available before collecting all necessary effectiveness data, but after proving that the drug is safe in accordance with the full FDA approval standard and that a reasonable expectation of effectiveness exists.

During the five-year period of conditional approval, AB Science will continue to gather data to further support the safety and efficacy of masitinib in designated indication.

Kinavet-CA1 is available to all U.S. veterinarians. The registration issued by the FDA does not restrict the sale of the drug, Ahn said when asked whether the drug would be limited to veterinary oncologists.

Masitinib may be made available soon to doctors in human medicine.

“Masitinib is being developed in human medicine for a number of different cancers and also inflammatory diseases,” Ahn said. “We have a number of stage two and stage three clinical trials that are under way.”

Ahn noted that this is one example where a drug was first introduced in veterinary medicine. In most cases, drugs start in the human field and then enter the veterinary sector, he said.

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“[This demonstrates AB Science’s] philosophy of recognizing that cancer is a comparative disease phenomenon,” Ahn said. “Here is a specific example where we are able to utilize a technological breakthrough in veterinary medicine to also help human patients.”

Ahn said the company hopes to see the human regulatory process moving along within the next couple of years.

Long-Term Prospects

As for the future in general?

“We are looking forward to initially making the drug available for pets that are suffering from mast cell tumors,” he said. “We are also committed to performing more clinical studies because we have reason to believe that there may be other cancer and other inflammatory diseases that may benefit from this particular drug.”

In essence, AB Science wants to identify the full therapeutic range and potential for masitinib, he said. The company’s research and development labs are developing additional targeted therapies for other diseases.

This is an exciting time in veterinary medicine, Ahn said.

“As a veterinarian, I am truly proud of the commitment and hard work that the AB Science team has invested into bringing Kinavet-CA1 to the marketplace,” he said. “I’ll be working closely with the oncology community to continue to explore ways to expand the clinical utilities of Kinavet-CA1.”


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