• Asparagine;
  • CCNU;
  • Dog;
  • Lymphosarcoma;
  • Rescue protocol

Background: The combination of lomustine, l-asparaginase, and prednisone (LAP) is an effective rescue treatment for canine lymphoma (LSA). In a previous study, we reported that remission was typically lost around the time l-asparaginase was discontinued.

Hypothesis: Use of l-asparaginase with each lomustine treatment will be well tolerated and efficacious as a rescue therapy for canine LSA.

Animals: Forty-eight client-owned dogs with cytologically confirmed multicentric LSA whose disease had relapsed after a cyclophosphamide, doxorubicin, vincristine, and prednisone-based chemotherapy protocol were included.

Methods: Lomustine was administered orally at 3-week intervals, concurrently with subcutaneous or intramuscular l-asparaginase for a total of 5 doses or until disease progression. Prednisone was administered at a tapering dose for the duration of the protocol.

Results: The overall response rate (ORR) for dogs treated with this protocol was 77%, with 65% achieving a complete response (CR). The median time to progression (TTP) was 70 days. Based on loose comparison, these findings are not significantly different from our previously reported historical control. The actual CCNU dosage administered did not affect response rate or remission duration.

Conclusions/Clinical Importance: These findings support previous data concluding that the LAP protocol is a viable rescue treatment option for dogs with LSA. However, results from this study suggest that continued use of l-asparaginase with each lomustine treatment does not significantly increase remission duration and toxicity appears greater.