Combination chemotherapy with L-asparaginase, lomustine, and prednisone for relapsed or refractory canine lymphoma

Canine lymphoma (LSA) is responsive to initial treatment, however, it then becomes resistant to drugs in the initial protocol. New rescue protocols are needed.

A combination of L-asparaginase, lomustine, and prednisone will be well tolerated and efficacious as a rescue therapy for dogs with LSA.

Thirty-one client owned dogs with cytologically confirmed multicentric LSA who were refractory or whose disease had relapsed after a CHOP (cyclophosphamide/doxorubicin/vincristine/prednisone)-based chemotherapy protocol.

Prospective clinical trial. Lomustine (target dose, 70 mg/m2) was administered orally at 3-week intervals for a total of 5 doses or until disease progression. L-asparaginase (400 U/kg) was administered subcutaneously concurrently with the first 2 lomustine treatments. Prednisone was administered at a tapering dose for the duration of the protocol.

Overall response rate for dogs treated with this protocol was 87% (27/31), with 52% (16/31) of dogs achieving a complete response. Median time to response was 21 days. Median time to progression was 63 days (111 days for dogs achieving a complete response and 42 days for dogs achieving a partial response). There were no significant differences in response rates and times to progression between dogs who had received L-asparaginase before beginning this rescue protocol and those who had not. Toxicoses were mild and self-limiting in 29 of 31 cases.

This is a well-tolerated rescue therapy for relapsing LSA in dogs. Response rates and remission durations compare favorably to other rescue protocols. Therefore, this protocol is a viable rescue option.