Pet company Aratana Therapeutics Inc (NASDAQ:PETX) reported on Wednesday the receipt of the US Department of Agriculture's (USDA) Center for Veterinary Biologics conditional licensure for Canine Osteosarcoma Vaccine, Live Listeria Vector (AT-014) for the treatment of dogs diagnosed with osteosarcoma, one year of age or older.

The company has developed Canine Osteosarcoma Vaccine, a novel immunotherapy, using a listeria based antigen delivery system licensed from Advaxis Inc (NASDAQ:ADXS).

Canine Osteosarcoma Vaccine is a lyophilized formulation of a modified live, attenuated strain of listeria that activates cytotoxic T-cells. It directs the T-cells to fight cancer cells, even after the bacteria are cleared. The therapeutic capitalises on the dog's immune system and attacks bacterial infections, thus redirecting it to fight cancer cells.

In conjunction, the data from the company's clinical study in 18 client-owned dogs with osteosarcoma suggests that the immunotherapy may be able to delay or prevent metastatic disease and prolong overall survival in dogs. The single-arm study evaluated dogs that had primary tumour removal and four doses of carboplatin chemotherapy, followed by the therapeutic vaccine every three weeks for three doses. Median survival time was 956 days compared to 423 days for a historical control group.

To progress from conditional licensure to full licensure, the company intends to launch an extended field study in a clinical setting and anticipates initiating the study in early 2018 under the USDA regulations. The therapeutic will be made available for purchase at two dozen veterinary oncology practice groups across the US.