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An Urban Experience
In 2011, vinblastine was evaluated in 28 dogs with tumor responses of 36% partial response, 50% stable disease and 14% progressive disease. Treatment was well tolerated in in 27 of 28 dogs. Median survival time (MST) was 147 from 1st vinblastine to death and 299 days from diagnosis to death. Vinorelbine has also been evaluated as rescue therapy in 13 dogs. Two dogs (14%) had partial response and 8 (57%) had stable disease. Subjective improvement was noted in 11 dogs (78%). Median progression free interval was 93 days (20-239 d). MST was 187 days and MST of pre-treated dogs was 207 days.
In 2013, metronomic (low dose oral) administration of chlorambucil has also been evaluated (4 mg/m2 PO q 24 hours). 29 of 31 dogs had failed previous treatment. Of 30 dogs, 1 dog (3%) had partial response, 20 (67%) had stable disease, and 9 (30%) had progressive disease. Median progression free interval was 119 days (7-728 d). MST was 221 days (7-747 d) from start of chlorambucil. Treatment was well tolerated and only discontinued due to toxicity in one dog. 70% had partial response or stable disease.
In 2015, a study compared piroxicam in combination with mitoxantrone or carboplatin in 50 dogs, and the response was not different between the groups. None of the dogs showed complete response. In the mitoxantrone group, there were 2 (8%) partial responses (PR) and 18 (69%) dogs with stable disease (SD). In
the carboplatin group, there were 3 PR (13%) and
13 (54%) dogs with SD. The PFI was not significantly different between groups (mitoxantrone = 106
days; carboplatin = 73.5 days). Dogs with prostatic involvement experienced a shorter survival (median, 109 days) compared to dogs with urethral, trigonal, or apically located tumors; this difference was significant (median 300, 190, and 645 days, respectively).
In 2016, a pilot study evaluated 5 dogs receiving vinblastine at 1.6 mg/m2 every 2 weeks and toceranib (Palladia) at 2.5-2.75 mg/kg on Monday/Wednesday/ Friday. Tumor monitoring was achieved through CT and abdominal ultrasound (AUS). Both imaging modalities were found to provide repeatable measurements between operators, however agreement between operator measurements was greater when CT images were used to assess tumor size. The combination of toceranib and vinblastine did not result in improved response rates but there were only 5 dogs. While agreement in tumor volume assessments between both AUS and CT were excellent between operators, this
did not extend to assessment of tumor response. The higher rate of concordance between operators when assessing response to treatment with CT suggests that CT should be considered for future clinical trials involving canine bladder TCC to improve the accuracy and repeatability of tumor measurement. The data suggest
that response to therapy as assessed by AUS or CT do not predict duration of clinical response.
References and Additional Reading
1. Knapp DW, McMillan SK. Tumors of the Urinary System. In: Small Animal Clinical Oncology. 5th ed. St. Louis Missouri: Elsevier Saunders; 2013: 572-582.
2. Bryan JN. Transitional Cell Carcinoma. In Clinical Veterinary Advisor Dogs and Cats. 3rd edition. St. Louis Missouri: Elsevier Mosby; 2015: 1015-1016
3. Henry CJ. Bladder and Urethral Tumors. In Cancer Management in Small Animal Practice. Saunders 2010. 290-295
4. Allstadt SD, et al, Randomized phase III trial of piroxicam in combination with mitoxantrone or carboplatin for first-line treatment of urogenital tract transitional cell carcinoma in dogs. J Vet Intern Med. 2015 Jan;29(1):261-7.
5. Arnold EJ, et al. Clinical trial of vinblastine in dogs with transitional cell carcinoma of the urinary bladder. J Vet Intern Med. 2011 Nov-Dec;25(6):1385-90.
6. Fulkerson CM, Knapp DW. Management of transitional cell carcinoma of the urinary bladder in dogs: a review. Vet J. 2015 Aug;205(2):217-25.
7. Kaye ME, et al. Vinorelbine rescue therapy for dogs with primary urinary bladder carcinoma. Vet Comp Oncol. 2015 Dec;13(4):443-51.
8. Knapp DW, et al. Detection of herbicides in the urine of pet dogs following home lawn chemical application. Sci Total Environ. 2013 Jul 1;456-457:34-41.
9. McMillan SK, et al. Antitumor effects of deracoxib treatment in 26 dogs with transitional cell carcinoma of the urinary bladder. J Am Vet Med Assoc. 2011 Oct 15;239(8):1084-9.
10. Rippy SB, et al. A pilot study of toceranib/vinblastine therapy for canine transitional cell carcinoma. BMC Vet Res. 2016 Nov 17;12(1):257.
11. Schrempp DR, et al. Metronomic administration of chlorambucil for treatment of dogs with urinary bladder transitional cell carcinoma. J Am Vet Med Assoc. 2013 Jun 1;242(11):1534-8.

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