Introduction

CHOP chemotherapy remains the standard treatment for canine multicentric lymphoma but is rarely curative. In contrast, CHOP cures approximately 30–40% of humans with diffuse large B-cell lymphoma. This difference in outcomes may be partially explained by the greater dose intensity of human CHOP protocols.

Methods

To increase the dose intensity of canine CHOP protocol without significantly augmenting toxicity, we used the principle of summation dose intensity (SDI) to derive a novel combination CHOP chemotherapy protocol that models human dosing schedules. Our hypothesis was that the new protocol would be well tolerated when given to healthy mixed-breed laboratory dogs. Three dogs >1 year of age and weighing >20 kg were enrolled in a 42-day pilot trial. All dogs received cyclophosphamide (62.5 mg/m² PO), vincristine (0.35 mg/m² IV), and doxorubicin (7.5 mg/m² IV) on day 1, and prednisone (50 mg/m² PO) on days 1–5. On day 22, all dogs received escalated dosages of cyclophosphamide 83.3 mg/m² PO, vincristine 0.47 mg/m² IV, and doxorubicin 10 mg/m² IV. Prednisone was given at 50 mg/m² PO on days 22–26. Antiemetic and antimicrobial prophylaxis was provided to all dogs.

Results

Treatment-related adverse events were mild and responsive to supportive care. All dogs developed grade 2 (2) or 3 (1) neutropenia 10 days after the second treatment, all of which resolved within 72 hours.

Conclusion

The excellent tolerability of this novel CHOP chemotherapy regimen in laboratory dogs supports efficacy testing in cancer-bearing dogs.

Funding Information

Purdue University Center for Cancer Research