CHOP protocol for stage IIIa canine B-cell lymphoma — dos...

Of course, happy to provide my approach for a new Stage IIIa B-cell lymphoma case. This is our most common presentation, and CHOP remains the gold standard for good reason. The key is consistent monitoring and proactive management of side effects to maintain that crucial quality of life.

Here is the 25-week induction protocol I typically use, followed by monitoring and rescue considerations.

CHOP Protocol (UW-Madison Protocol)

The goal is to achieve a rapid and durable first remission. The first remission is always the best one, so we hit it hard from the start.

* Week 1: Vincristine 0.7 mg/m² IV
* Week 2: Cyclophosphamide 250 mg/m² PO
* Week 3: Vincristine 0.7 mg/m² IV
* Week 4: Doxorubicin 30 mg/m² IV (slow infusion)
* Week 5: Rest Week

This 5-week block is one cycle. We repeat for a total of 5 cycles (25 weeks). I also start Prednisone at 2 mg/kg PO daily for the first week, then taper down by 25% each week for 4 weeks and discontinue.

Key Monitoring & Clinical Pearls

Pre-Doxorubicin: For any predisposed breed (Doberman, Boxer, etc.) or any patient with a murmur, I require a baseline echocardiogram before the first doxorubicin dose.

Cyclophosphamide: Always dispense with furosemide (2 mg/kg PO) to be given at the same time. Instruct the owner to administer the cyclophosphamide in the morning to encourage urination throughout the day, minimizing bladder contact time and the risk of sterile hemorrhagic cystitis.

Bloodwork: I check a CBC before every single chemotherapy administration. My general rule is to proceed if the absolute neutrophil count (ANC) is >1,500/µL and platelets are >50,000/µL. If below, we delay for 3-7 days and recheck. A chemistry panel is warranted at baseline and then every 1-2 cycles.

Remission Check: We expect a dramatic reduction in lymph node size after Week 1. I document lymph node measurements at every visit. A formal restaging (thoracic rads, abdominal US) is done after the first cycle and at the end of the protocol.

With this protocol, you can tell the owner to expect an 85-90% first remission rate, with a median survival time of 12-14 months of excellent quality life.

Rescue Protocol Options

When relapse occurs (typically 2-3 months after finishing CHOP), a second remission is often achievable, though it will be shorter. My go-to options are:

* Lomustine (CCNU): A good single-agent option. Dose is 70-90 mg/m² PO every 3-4 weeks. The critical watch-out here is cumulative hepatotoxicity; monitor liver enzymes before every dose.
* LAP (Lomustine, L-Asparaginase, Prednisone): A common multi-agent rescue.
* Rabacfosadine (Tanovea): A newer, effective option specifically labeled for canine lymphoma. Dose is 1 mg/kg IV every 3 weeks for up to 5 doses. Watch for dermatologic side effects.

The choice of rescue depends on the duration of the first remission, prior toxicities, and owner finances. Let me know if you have any questions as you get started.