Lymphoma in dogs: rabacfosadine (Tanovea) vs placebo — PROBABLE

In dogs with naïve or relapsed multicentric lymphoma, does rabacfosadine improve response and progression-free interval vs placebo?

Shelf #103 · gate-verified and displayed under the developer's blinded-trial rule

PROBABLE: Rabacfosadine has real antitumour activity in canine multicentric lymphoma. In the single decisive licensure trial — a multicenter, randomized, double-blinded, placebo-controlled study of 158 client-owned dogs with naïve or relapsed multicentric lymphoma, randomised 3:1 to rabacfosadine or placebo every 21 days for up to 5 treatments — median progression-free survival was 82 days on rabacfosadine vs 21 days on placebo (P < .0001), and best overall response rate was 73.2% (50.9% complete, 22.3% partial) vs 5.6% (0% complete, 5.6% partial) on placebo (P < .0001), an absolute difference of about 68 percentage points (Weishaar 2022). This is a progression/response claim, not a lifespan claim: the trial reported progression-free survival and response, not overall survival, and no life-lengthening benefit is carded here. The cost was frequent, generally low-grade and reversible gastrointestinal adverse events. This shelf rests on that one trial, stated on its face; it clears the VetMed single-trial bar because the trial is large, blinded, placebo-controlled and decisive on its endpoints. Drafted Nov 10, 2026 (VetMed build, topic #103); all figures from abstracts fetched and verified at drafting.

Weishaar 2022: rabacfosadine median progression-free survival 82 vs 21 days on placebo, best response 73.2% vs 5.6% (both P < .0001)

Multicenter, randomized, double-blinded, placebo-controlled study (record's own title wording); indexed as Randomized Controlled Trial, Veterinary

Who: Dogs: 158 client-owned dogs with naïve or relapsed multicentric lymphoma, prospectively enrolled from January to October 2019 in a multicenter study; dogs were randomized to receive rabacfosadine (Tanovea-CA1) or placebo at a 3:1 ratio, given every 21 days for up to 5 treatments.

Result: The median progression-free survival (PFS) was significantly longer in the rabacfosadine group compared to placebo (82 vs 21 days; P < .0001, relative hazard ratio 6.265 [95% CI 3.947–9.945], as printed in the record). The best overall response rate (BORR) for rabacfosadine-treated dogs was 73.2% (50.9% complete response, 22.3% partial response) and 5.6% (0% complete response, 5.6% partial response) for placebo-treated dogs (P < .0001) — an absolute difference of about 68 percentage points. One month after the last treatment, 37 rabacfosadine-treated dogs (33%) were progression free compared with no placebo-treated dogs (P < .0001). The most common adverse events in the rabacfosadine group were diarrhea (87.5%), decreased appetite (68.3%), and vomiting (68.3%), and were generally low grade and reversible. Serious adverse events were reported in 24 rabacfosadine-treated dogs (20%) and 5 placebo-treated dogs (13%).

Watch out: Single trial carries this shelf (stated on its face). Progression-free survival is time to progression, not overall survival — the record reports no overall-survival result, so no lifespan claim should be read into this stamp. The record prints the hazard ratio of 6.265 alongside the longer median PFS on rabacfosadine but does not state the reference group for that ratio in the abstract; it is reproduced here exactly as printed, and the absolute medians (82 vs 21 days) carry the clinical meaning. Gastrointestinal adverse events were very common on rabacfosadine, even if generally low grade. The trial's title establishes the double-blinded design; the MeSH list itself carries no Double-Blind Method or Random Allocation term.

Weishaar KM, Wright ZM, Rosenberg MP et al. Multicenter, randomized, double-blinded, placebo-controlled study of rabacfosadine in dogs with lymphoma. J Vet Intern Med. 2022;36(1):215-226. PMID: 34952995. Registry ID: none in the record. MeSH: Alanine · Animals · Antineoplastic Combined Chemotherapy Protocols · Dog Diseases · Dogs · Lymphoma · Purines · Treatment Outcome

Synthesis: one decisive blinded licensure trial — progression delayed and responses real, survival not asked

Synthesis

Who: Synthesis of the card above: Weishaar 2022 (multicenter, randomized, double-blinded, placebo-controlled study; 158 dogs with naïve or relapsed multicentric lymphoma, randomised 3:1, rabacfosadine or placebo every 21 days for up to 5 treatments).

Result: A 61-day absolute gain in median progression-free survival (82 vs 21 days) and a roughly 68-percentage-point absolute gain in best overall response (73.2% vs 5.6%), both at P < .0001 in a blinded placebo-controlled trial of 158 dogs, is a decisive single-trial antitumour result, which is why this single-trial shelf carries PROBABLE under the VetMed charter's one-trial exception. What the trial does not show is longer overall survival, and the median progression-free interval on treatment was still under 3 months — real activity, measured in weeks to a few months, at the price of very common gastrointestinal adverse events.

Watch out: Trial dogs were monitored under licensure-trial conditions; the serious adverse event rate was 20% on rabacfosadine vs 13% on placebo in the record, alongside the very high rates of diarrhoea, decreased appetite and vomiting, so case selection and owner counselling matter in practice.

Synthesis of Weishaar KM et al. PMID: 34952995. Registry ID as on the individual card.

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