TANOVEA®-CA1 (rabacfosadine for injection) is a novel double prodrug that targets cancerous lymphoma cells and is the first FDA conditionally approved drug for the treatment of lymphoma in dogs. Previous studies have suggested that administration of rabacfosadine every 3 weeks can achieve responses in B-and T-cell lymphoma in dogs both naive to, or no longer responding to prior chemotherapy treatment, with acceptable toxicity. A new study sought to assess rabacfosadine’s safety and efficacy specifically in dogs with relapsed B-cell lymphoma following initial conventional chemotherapy treatment (first-line rescue setting).
The study, recently published in Veterinary and Comparative Oncology, involved 50 dogs that had previously failed one doxorubicin (DOX)-containing chemotherapy protocol — a common, but unapproved approach for treating multicentric lymphoma in dogs. Dogs were randomized to receive rabacfosadine at either 0.82 mg/kg or 1.0 mg/kg as a 30-minute IV infusion every 3 weeks for up to five treatments. Of the 50 dogs enrolled, 16 were treated at 0.82 mg/kg and 34 were treated at 1.0 mg/kg. The overall response rate across both groups was 74%, with a median response duration of approximately six months in all responders.
Full details of the study are available online.
The results indicate that rabacfosadine is a promising first-line rescue treatment option for dogs with B-cell lymphoma following a DOX-containing chemotherapy protocol. The overall response rate across both groups was 74%, with 45% of dogs experiencing a complete response (CR). The median progression-free intervals (PFIs) were 108 days, 172 days, and 203 days for all dogs, all responders, and all complete responders, respectively. There were no significant differences between the two dosages in terms of response rate, PFI, response duration, or Adverse Events (AEs), however, differences in sample sizes may have limited the ability to detect differences between groups.
Importantly, the authors of the study support rabacfosadine treatment at the 1.0 mg/kg (currently labeled dose) as it appears reasonably well tolerated, especially when supportive medications and drug holidays are used to minimize adverse events. Across both dose groups, side effects were similar and included hematologic, gastrointestinal, dermatologic and pulmonary AEs. Other than one dog that developed signs consistent with grade 5 pulmonary fibrosis at the 0.82 mg/kg dose, other adverse events were mostly self-limiting and resolved with supportive care and/or dosage modification.
In summary, TANOVEA-CA1 (rabacfosadine for injection) used at a dosage of 1.0 mg/kg every 3 weeks for up to five doses is a generally well tolerated and viable first-line rescue option for dogs with relapsed B-cell lymphoma. Reducing the dose from 1.0 mg/kg to 0.82 mg/kg, as needed to address adverse events, does not appear to adversely affect TANOVEA’s efficacy. Careful monitoring for the unique dermatologic and pulmonary toxicities is warranted in dogs receiving this novel lymphoma treatment.