Mast cell tumour in dogs: toceranib (Palladia) vs placebo — PROBABLE

In dogs with unresectable/recurrent grade II–III mast cell tumours, does toceranib increase objective response rate vs placebo?

Shelf #107 · gate-verified and displayed under the developer's blinded-trial rule

PROBABLE: Toceranib has real antitumour activity against recurrent canine mast cell tumours after surgical excision. In the single decisive trial — a multi-center, placebo-controlled, double-blind, randomized study — the blinded-phase objective response rate was 37.2% on toceranib (7 complete and 25 partial responses, n = 86) versus 7.9% on placebo (5 partial responses, n = 63; P = 0.0004), an absolute difference of about 29 percentage points. Dogs that crossed over from placebo to open-label toceranib responded at 41.4%, consistent with the blinded result. This is a response-rate claim, not a survival claim: the trial was not built to show that toceranib lengthens life, and no survival benefit is carded here. 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 endpoint. Drafted Nov 10, 2026 (VetMed build, topic #107); all figures from abstracts fetched and verified at drafting.

London 2009: toceranib objective response 37.2% vs 7.9% on placebo in the blinded phase (P = 0.0004)

Multi-center, placebo-controlled, double-blind, randomized study (record's own title wording)

Who: Dogs: dogs with recurrent (local or distant) mast cell tumour following surgical excision, in a multi-center trial — blinded phase: 86 dogs randomised to oral toceranib phosphate (Palladia, SU11654) 3.25 mg/kg every other day for 6 weeks and 63 to placebo; eligible dogs then received open-label toceranib.

Result: Blinded-phase objective response rate was 37.2% on toceranib (7 complete response, 25 partial response) versus 7.9% on placebo (5 partial response) (P = 0.0004). Of 58 dogs that received toceranib following placebo-escape, 41.4% (8 complete, 16 partial) had an objective response. The objective response rate for all 145 dogs receiving toceranib was 42.8% (21 complete, 41 partial); among the 62 responders, median duration of objective response was 12.0 weeks and median time to tumour progression 18.1 weeks. Toceranib-treated responders scored higher on health-related quality of life than toceranib-treated nonresponders (P = 0.030). There was no significant difference in the number of dogs with grade 3/4 adverse events, and adverse events were generally manageable with dose modification and/or supportive care.

Watch out: Single trial carries this shelf (stated on its face). The endpoint is objective tumour response, not survival — no life-lengthening claim is made. The 145-dog figure is all dogs that ever received toceranib (blinded plus open-label crossover), not the blinded-phase denominator. The record's publication type is indexed only as Journal Article; the randomised, double-blind, placebo-controlled design is established by the article title and abstract, and by the MeSH term Random Allocation.

London CA, Malpas PB, Wood-Follis SL et al. Multi-center, placebo-controlled, double-blind, randomized study of oral toceranib phosphate (SU11654), a receptor tyrosine kinase inhibitor, for the treatment of dogs with recurrent (either local or distant) mast cell tumor following surgical excision. Clin Cancer Res. 2009;15(11):3856-65. PMID: 19470739. Registry ID: none in the record. MeSH: Animals · Anorexia · Diarrhea · Disease Progression · Dog Diseases · Dogs · Female · Indoles · Male · Mast-Cell Sarcoma · Neoplasm Recurrence, Local · Pyrroles · Random Allocation · Receptor Protein-Tyrosine Kinases · Treatment Outcome · Vomiting

Synthesis: one decisive blinded trial — response is proven, survival is not asked

Synthesis

Who: Synthesis of the card above: London 2009 (multi-center, placebo-controlled, double-blind, randomized study; blinded phase 86 toceranib vs 63 placebo dogs with recurrent mast cell tumour after excision).

Result: A roughly 29-percentage-point absolute gain in objective response (37.2% vs 7.9%, P = 0.0004), reproduced at 41.4% when placebo dogs crossed over to the drug, is as decisive a single-trial response result as veterinary oncology offers, 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 survival, and clinicians should not let a response-rate stamp harden into a prognosis claim; median time to progression among responders was 18.1 weeks, a reminder that responses are real but usually measured in months.

Watch out: Toceranib's adverse events (the record's MeSH flags anorexia, diarrhoea and vomiting) were manageable in the trial with dose modification and supportive care, with no significant excess of grade 3/4 events — but trial dogs are monitored more closely than most patients.

Synthesis of London CA et al. PMID: 19470739. Registry ID as on the individual card.

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