Combination chemotherapy with vincristine, cyclophosphamide, and prednisone producing long-term remission of a transplanted canine lymphoma.

Lymphoma developed in 6 neonatal pups inoculated with 1.0 to 2.06 X 10(9) cells of the 2nd in vivo passage of a canine lymphoma. Three to 4 weeks later (or 8 weeks after the pups had been inoculated), 3 of the 6 pups were started on a chemotherapeutic regimen consisting of vincristine, prednisone, and cyclophosphamide. Twelve to 19 days after combination chemotherapy was started, clinically efident lymphoma disappeared in the 3 pups. Period of treatment was 49 to 84 days. The dogs remained healthy and lymphoma was in complete remission approximately 2 years later. The 3 nontreated pups, used as controls, died of generalized lymphoma 45 to 86 days after inoculation. Seemingly, chemotherapy eradicated the bulk of the tumor, and the host immune response was capable of eliminating residual neoplastic cells. Also, transplanted canine lymphoma seems amenable to treatment and may be curable with combination chemotherapy--thus possibly serving as an experimental therapeutic model.