Is CCNU (lomustine) valuable for treatment of cutaneous epitheliotropic lymphoma in dogs? A critically appraised topic
© The Author(s). 2017
Received: 12 November 2016
Accepted: 15 February 2017
Published: 21 February 2017
CCNU and other treatment protocols are commonly offered to owners for the treatment of dogs diagnosed with cutaneous (epitheliotropic) T-cell lymphoma (CTCL). Chemotherapy protocols provide variable benefits; they have different side-effects, and they typically require monitoring to detect drug toxicity at a non-negligible cost to the owner. At this time, even though CCNU is most often recommended to treat dogs with CTCL, there is no clear consensus on the benefit of this drug. Knowing which chemotherapy protocol yields the highest rate of complete remission and longest survival times would help veterinarians and pet owners select treatment options based on the best evidence available. Our objective was to review the literature to compare the complete remission rates and survival times of CCNU-based protocols to those of other interventions. We critically assessed the data included in articles reporting treatment outcome in at least five dogs with CTCL. Single case reports and case series with less than five patients were not reviewed to avoid anecdotal evidence of lower quality.
The search for, and review and analysis of, the best evidence available as of February 8, 2017, suggests that CCNU and pegylated liposomal doxorubicin appear to yield the highest rate of complete remission in approximately one-third of dogs with CTCL. Other treatment protocols did not report usable information on remission rates. Without any treatment, the mean/median survival time in dogs with CTCL varied between 3 and 5 months. With CCNU protocols, the median survival time was 6 months and the one with retinoids (isotretinoin and/or etretinate), PEG L-asparaginase or prednisolone monotherapy was 11, 9 and 4 months, respectively; all these durations were obtained from small numbers of dogs, however.
CCNU leads to a complete remission of signs in approximately one-third of dogs with CTCL, but such remissions are of short duration. The median survival time after CCNU appears longer than that without treatment, but other drugs appear to provide a better long-term prognosis. Further studies are required to investigate the effect of CCNU, alone or in combination, on remission rates, survival times and impact on quality of life.
KeywordsCanine Chemotherapy Dog Epitheliotropic Lomustine Lymphosarcoma Mycosis fungoides Neoplasia
Lomustine (CCNU) or other chemotherapy protocols are commonly offered to owners for the treatment of their dogs diagnosed with cutaneous (epitheliotropic) T-cell lymphoma (CTCL). Although these regimens are expected to lead to a temporary partial or complete remission (CR) of skin lesions, monitoring for the detection of common severe adverse events requires regular laboratory monitoring that might represent a significant financial burden to the clients . At this time, there is no clear consensus on the benefit of the various treatment regimens for dogs with CTCL.
Knowing which chemotherapy protocol has the strongest evidence for yielding the best complete remission rates and longest survival times would help veterinarians and pet owners select treatment options based on the best evidence available. Our objective was to review the literature to compare the complete remission rates and survival times of CCNU-based protocols to those of other interventions.
You have two patients: The first one is a 5-year-old female Labrador retriever crossbred dog. The owners report that the lesions started 2.5 months beforehand and that they consisted, at first, of generalized scaling and pruritus. They evolved into multifocal areas of truncal alopecia and erythema along with an ulcer on the caudal abdomen. The dog was placed on a tapering course of prednisone that led to a reduction in clinical signs. After discontinuing the steroids, the dog developed alopecic erythematous macules, patches and plaques, and she became more pruritic than before.
Your second patient is a 12-year-old male golden retriever presenting with multifocal large patchy areas of hypopigmentation and depigmentation along with multifocal erythematous plaques and nodules. The owner reports that the dog may have had depigmented muzzle lesions for the past 2 years.
In both cases, skin biopsies confirmed your suspicion of CTCL. You wonder which chemotherapeutic option would be most beneficial for these two dogs.
In a dog with CTCL, which chemotherapeutic treatment protocol would be most effective to induce the CR of clinical signs and to lead to the longest survival?
The CAB Abstracts and Web of Science (WoS) Science Citation Index Expanded databases were searched on April 26, 2016 for relevant articles using the following string: (dog or dogs or canine) and (cutaneous or epitheliotropic or epidermotropic) and (lymphoma or lymphosarcoma) and (CCNU or lomustine or vincristine or cyclophosphamide or chlorambucil or predniso* or chemotherap*). The search was limited to the period 1980–2016. We then screened the bibliographies of identified articles for additional relevant reports. At the time of revision of this manuscript (Febuary 08, 2017), a second broad literature search was done to identify papers published since the first search.
Results and discussion
Our literature search found 63 and 65 articles in the CAB Abstract and Web of Science (WoS) databases, respectively. Citations were initially examined for the identification of articles reporting the outcome of treatment in dogs with CTCL diagnosed via histopathology. We then evaluated abstracts, and articles with potentially relevant information were read in full. The bibliography of these papers was analyzed further for additional pertinent reports.
We only selected articles that provided definite information on the rate of CR /or survival times after diagnosis or treatment of at least five dogs with CTCL; articles and information on partial remission were not reviewed further.
Two retrospective [2, 3] and one prospective studies  providing clear information on CR rates in dogs with CTCL were found in both CAB and WoS databases. One preclinical trial  and one pilot study  were subsequently added following the review of the bibliographies of articles identified in the electronic searches. Finally, we added one last article that had been published after the performance of our initial literature search .
For survival times after diagnosis or treatment, one retrospective study  and one prospective study  were identified in the CAB abstracts, one of which was also found in the WoS . A prospective  and a retrospective study  were added following the review of bibliographies of articles found in the electronic search.
Evaluation of evidence
Complete remission rates
Rates of complete remission in dogs with CTCL
Pegylated liposomal doxorubicin
VDC-1101 and prednisone
CR (N, %)
CR (N, %)
CR (N, %)
CR (N, %)
Morges, 2014 
Risbon, 2006 
Williams, 2006 
Graham, 1999 
Vail, 1997 
Holtermann, 2016 
Altogether, CCNU, alone or in conjunction with other concurrent medications, yielded a combined rate of CR of 30% of the 87 dogs reported [2, 3, 6]. The median duration of CR, estimated from only 15 dogs in one article , was 132 days (range: 26–258 days). The time to achieve CR was not identified in any article. In one report of 46 dogs , the overall median number of treatments needed to observe a response (type not specified) was one (range: one to six cycles).
A similar rate of CR occurred with pegylated liposomal doxorubicin, but the number of dogs treated (nine) was low . The median duration of CR was shorter (90 days, range: 21–340) than with CCNU; the time to CR was not reported either.
The prednisone and VDC-1101 combination did not lead to CR in any of the ten dogs to which it was administered .
Finally, masitinib induced a CR of signs of CTCL in 2/10 treated dogs (20%); this remission lasted for 126 days in one dog and over 3 years in the other .
Survival times after diagnosis or treatment initiation
The median/mean survival times were, in order of decreasing durations, 11 months after treatment with the retinoids isotretinoin and/or etretinate , 9 months after PEG L-asparaginase , 6 months after CCNU protocols  and 4 months after prednisolone alone .
The main limitation of this compilation is that any confounding effect of the dog’s age, CTCL severity, CTCL stage or time before the diagnosis was made or treatment initiated were not evaluated for their possible impact on CR or survival times in any of these studies. Another limitation is that CCNU was used alone in only one-third of dogs in the largest case series [2, 3], and the rates of CR were not compared between dogs receiving CCNU monotherapy and those treated with combination regimens. Furthermore, the survival times provided were likely to have been influenced by euthanasia decisions by the owner, thereby not reflecting disease-induced death. Finally, many of the estimates provided herein were only assembled from a small number of patients.
Implications for practitioners
In spite of the limitations raised above, and taking into consideration the best evidence available, CCNU protocols, when used alone or in combination with other drugs, appear to lead to CR rates of 30%, but the median duration of such CRs remains unclear. The median survival time of CTCL after CCNU protocols is 6 months following diagnosis. Retinoids or PEG L-asparaginase appear to offer longer median survival times, but these drugs are not routinely available.
At the time of this writing, CCNU—alone or in combination with other drugs—appears to be a valuable option to treat dogs with CTCL; unfortunately, the common occurrence of myelopoietic and/or gastrointestinal side effects requires frequent blood test monitoring that increases the cost of treatment.
Implication for research
Additional studies are needed to compare the rates of CR and survival times using glucocorticoids, CCNU or retinoids (e.g. bexarotene), either alone or in various combinations thereof. Because of the potential toxicity and side effects of CCNU, the quality of life in dogs receiving CCNU protocols should be compared to that without any treatment or with other medications. Future studies should also attempt to compare CR rates and survival times in dogs of various age groups as well as in those with variable duration of clinical signs, stages or severities of CTCL.
1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (i.e. lomustine)
cutaneous T-cell lymphoma
Availability of data and materials
The data analyzed during the current study are available from the corresponding author on reasonable request.
The two authors selected the topic of this CAT; AFL performed the literature search, extracted and summarized the evidence; TO verified the evidence and both authors contributed to the writing of this article.
The authors declare that they have no competing interests.
Consent for publication
Not needed or relevant.
Ethics approval and consent to participate
Not needed or relevant.
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
- Heading KL, Brockley LK, Bennett PF. CCNU (lomustine) toxicity in dogs: a retrospective study (2002-07). Aust Vet J. 2011;89:109–16.View ArticlePubMedGoogle Scholar
- Risbon RE, de Lorimier LP, Skorupski K, Burgess KE, Bergman PJ, Carreras J, Hahn K, Leblanc A, Turek M, Impellizeri J, Fred 3rd R, Wojcieszyn JW, Drobatz K, Clifford CA. Response of canine cutaneous epitheliotropic lymphoma to lomustine (CCNU): a retrospective study of 46 cases (1999-2004). J Vet Intern Med. 2006;20:1389–97.PubMedGoogle Scholar
- Williams LE, Rassnick KM, Power HT, Lana SE, Morrison-Collister KE, Hansen K, Johnson JL. CCNU in the treatment of canine epitheliotropic lymphoma. J Vet Intern Med. 2006;20:136–43.View ArticlePubMedGoogle Scholar
- Morges MA, Burton JH, Saba CF, Vail DM, Burgess KE, Thamm DH. Phase II evaluation of VDC-1101 in canine cutaneous T-cell lymphoma. J Vet Intern Med. 2014;28:1569–74.View ArticlePubMedPubMed CentralGoogle Scholar
- Vail DM, Kravis LD, Cooley AJ, Chun R, MacEwen EG. Preclinical trial of doxorubicin entrapped in sterically stabilized liposomes in dogs with spontaneously arising malignant tumors. Cancer Chemother Pharmacol. 1997;39:410–6.View ArticlePubMedGoogle Scholar
- Graham JC, Myers RK. Pilot study on the use of lomustine (CCNU) for the treatment of cutaneous lymphoma in dogs [abstract 125]. Proceedings of the Proceedings of the 17th Annual Forum of the College of Veterinary Internal Medicine. Chicago: American College of Veterinary Internal Medicine; 1999.
- Holtermann N, Kiupel M, Kessler M, Teske E, Betz D, Hirschberger J. Masitinib monotherapy in canine epitheliotropic lymphoma. Vet Comp Oncol. 2016;14 Suppl 1:127–35.View ArticlePubMedGoogle Scholar
- Fontaine J, Heimann M, Day MJ. Canine cutaneous epitheliotropic T-cell lymphoma: a review of 30 cases. Vet Dermatol. 2010;21:267–75.View ArticlePubMedGoogle Scholar
- White SD, Rosychuk RA, Scott KV, Trettien AL, Jonas L, Denerolle P. Use of isotretinoin and etretinate for the treatment of benign cutaneous neoplasia and cutaneous lymphoma in dogs. J Am Vet Med Assoc. 1993;202:387–91.PubMedGoogle Scholar
- Moriello KA, Macewen G, Schultz KT. Peg L-asparaginase in the treatment of canine epitheliotropic lymphoma and histiocytic proliferative dermatitis. In: Ihrke PJ, Mason IS, White SD, editors. Advances in veterinary dermatology, vol. 2. 1993. p. 293–9.Google Scholar
- Beale KM, Bolon B. Canine cutaneous lymphosarcoma: epitheliotropic and non-epitheliotropic, a retrospective study. In: Ihrke PJ, Mason IS, White SD, editors. Advances in veterinary dermatology, vol. 2. New York: Pergamon Press; 1993. p. 273–84.Google Scholar