Long-term survival in dogs with localized histiocytic sarcoma treated with CCNU as an adjuvant to local therapy

Characterization of expression and prognostic implications of GD2 and GD3 synthase in canine histiocytic sarcoma

GD2 and GD3 are disialoganglioside oncofetal antigens important in oncogenesis. GD2 synthase (GD2S) and GD3 synthase (GD3S) are needed for GD2 and GD3 production. The objectives of this study are to validate the use of RNA in situ hybridization (RNAscope®) in the detection of GD2S and GD3S in canine histiocytic sarcoma (HS) in vitro and optimize this technique in canine formalin-fixed paraffin-embedded (FFPE) tissues. A secondary objective is to evaluate the prognostic significance of GD2S and GD3S on survival. Quantitative RT-PCR compared GD2S and GD3S mRNA expression between three HS cell lines followed by RNAscope® in fixed cell pellets from the DH82 cell line and FFPE tissues. Variables prognostic for survival were determined with Cox proportional hazard model. RNAscope® was validated for detection of GD2S and GD3S and optimized in FFPE tissues. GD2S and GD3S mRNA expression was variable between cell lines. GD2S and GD3S mRNA expression was detected and measured in all tumor tissues; there was no association with prognosis. GD2S and GD3S are expressed in canine HS and successfully detected using the high throughput technique of RNAscope® in FFPE samples. This study provides the foundation for future prospective research of GD2S and GD3S utilizing RNAscope®.

Characterization of expression and prognostic implications of transforming growth factor beta, programmed death-ligand 1, and T regulatory cells in canine histiocytic sarcoma

Histiocytic sarcoma (HS) is an aggressive malignant neoplasm in dogs. Expression and prognostic significance of transforming growth factor beta (TGF-β), programmed death-ligand 1 (PD-L1), and T regulatory cells (Tregs) in HS is unknown. The goal of this study was to investigate the expression and prognostic significance of TGF-β, PD-L1, and FoxP3/CD25 in canine HS utilizing RNA in situ hybridization (RNAscope®). After validation was performed, RNAscope® on formalin-fixed paraffin-embedded (FFPE) patient HS tissue samples was performed for all targets and expression quantified with HALO® software image analysis. Cox proportional hazard model was conducted to investigate the association between survival time and each variable. Additionally, for categorical data, the Kaplan-Meier product-limit method was used to generate survival curves. TGF-β and PD-L1 mRNA expression was confirmed in the DH82 cell line by reverse transcription polymerase chain reaction (RT-PCR) and CD25 + FoxP3 + cells were detected by flow cytometry in peripheral blood. Once the RNAscope® method was validated, TGF-β H-score and dots/cell and FoxP3 dots/cell were assessed in HS samples and found to be significantly correlated with survival. Moderate positive correlations were found between FoxP3 and PD-L1 H-score, percent staining area, and dots/cell, and FoxP3 and TGF-β dots/cell. In summary, RNAscope® is a valid technique to detect TGF-β and PD-L1 expression and identify Tregs in canine HS FFPE tissues. Furthermore, canine HS expresses TGF-β and PD-L1. Increased TGF-β and FoxP3 correlated with worse prognosis. Prospective studies are warranted to further investigate TGF-β, PD-L1, and Tregs effect on prognosis.

Comparison of the Clinical Characteristics of Histiocytic Sarcoma in Bernese Mountain Dogs and Flat-Coated Retrievers

Simple Summary

Histiocytic sarcoma (HS) is a malignant hematopoietic tumor. It can affect any organ in the body and, therefore, can have a broad spectrum of clinical presentations. So far, no complete overview exists of the array of clinical aspects of HS in specific dog breeds in large groups. Therefore, we investigated the clinical characteristics of HS in a population of Bernese Mountain Dogs (BMD; n = 365) and Flat-Coated Retrievers (FCR; n = 289), which are two of the most affected dog breeds. The dogs were selected from veterinary pathology services, and each dog’s clinical and diagnostic characteristics were retrospectively collected. Localized HS was reported significantly more frequently in the FCR (60.6%) than in the BMD (39.2%), and disseminated HS was recorded significantly more frequently in the BMD (60.8%) than in the FCR (39.4%). Lameness as a clinical symptom was observed more frequently in the FCR, predominant in the front legs. With blood examination, the BMD had significantly more often leukocytosis and thrombocytopenia, while no difference in the occurrence of anemia was observed. Strikingly hypercalcemia was only observed in 15 BMD and in none of the FCR in which blood examination was performed. The new information provided in this study can aid the diagnostic process and allow for prompt treatment recommendations.

Abstract

Histiocytic sarcoma (HS) is an aggressive malignant tumor of histiocytes, which can affect almost any organ in the body and is characterized by a broad array of tumor locations and clinical presentations. So far, no complete overview exists of the array of clinical aspects of HS in specific dog breeds in large groups. Therefore, we investigated the clinical characteristics of HS in a population of Bernese Mountain Dogs (BMD; n = 365) and Flat-Coated Retrievers (FCR; n = 289), which are two of the most affected dog breeds. Cases were selected from databases from different pathology services, and clinical information was retrospectively collected for each case. Localized HS was reported significantly more frequently in the FCR (60.6%) than in the BMD (39.2%), and disseminated HS was recorded significantly more frequently in the BMD (60.8%) than in the FCR (39.4%). Lameness was seen more often in FCR than in BMD, and the vast majority (78.1%) of LHS leading to lameness was located in the front legs in the FCR, while in the BMD, there was a more even distribution. BMD had significantly more often leukocytosis and thrombocytopenia, even corrected for the type of HS, than FCR. No significant difference in the frequency of anemia was recorded between BMD and FCR. In those dogs in which blood examination was performed, hypercalcemia was diagnosed in 15 BMD, while none of the FCR had hypercalcemia. The new information provided in this study can aid the diagnostic process and allow for prompt treatment recommendations.

mRNA sequencing analysis and growth inhibitory effects of palbociclib on cell lines from canine histiocytic proliferative disorders

Canine histiocytic proliferative disorders include aggressive and fatal diseases, such as histiocytic sarcoma (HS) and histiocytosis (SyH). The molecular mechanisms underlying cell proliferation need to be elucidated for the development of effective treatments. In the present study, mRNA expression levels were comprehensively analysed in cell lines derived from localized HS, disseminated HS, SyH and Langerhans cell histiocytosis (LCH) in dogs. Based on the results obtained, the growth inhibitory effects of palbociclib, a CDK4/6 inhibitor, were verified with the cell lines in vitro and in xenograft mouse model. Hierarchical clustering and principal component analysis plots of mRNA expression profiles divided the cell lines into three groups: a localized HS group, disseminated HS/SyH group, and LCH. The results of an ingenuity pathway analysis suggested that the MAPK signalling pathway was activated in the localized HS and LCH cell lines, and the PI3K signalling pathway in the disseminated and localized HS cell lines. In all cell lines, the expression of the tumour suppressor genes TP53, CDKN2A and CDKN1A was down-regulated, whereas that of Rb was preserved. In vitro assessments revealed the growth inhibitory effects of palbociclib in all cell lines examined. In a xenograft mouse model using a cell line from disseminated HS, palbociclib exerted significant growth inhibitory effects. These results suggest the potential of palbociclib as a therapeutic drug candidate for the treatment of malignant histiocytic proliferative disorders of the dog.

Doxorubicin for treatment of histiocytic sarcoma in dogs: 31 cases (2003-2017)

OBJECTIVE

To evaluate the efficacy of doxorubicin for treatment of histiocytic sarcoma (HS) in dogs, whether administered as the sole treatment or as an adjunct to surgery or radiation therapy.

ANIMALS

31 client-owned dogs with localized or disseminated HS examined between 2003 and 2017.

PROCEDURES

Medical records were reviewed retrospectively, and data were collected. The Kaplan-Meier method was used to estimate time-to-progression from the date of first doxorubicin administration and survival time from initial diagnosis. Factors that could be associated with poorer outcomes with doxorubicin treatment were analyzed with log-rank tests.

RESULTS

The objective response rate (ORR) was 26%. When stratified by disease status, dogs with localized and disseminated forms experienced 43% and 21% ORRs, respectively. Median time to progression after initiating doxorubicin treatment (n = 30 dogs) was 42 days. Median survival time from initial diagnosis to death (n = 29 dogs) was 169 days. Complete responses were obtained in only 2 dogs that had localized disease and received multimodality therapy.

CLINICAL RELEVANCE

Benefits of doxorubicin administration in canine HS are modest, with a limited ORR and delay in tumor progression, and are comparable to effects attained with other single-agent regimens.

Establishment and characterisation of cell lines and xenograft mouse models of canine systemic histiocytosis and disseminated histiocytic sarcoma

Canine histiocytic proliferative disorders include reactive diseases (histiocytosis) and neoplastic diseases (histiocytic sarcoma [HS]), however discrimination is challenging due to their overlapping pathological features. In the present study, novel cell lines and xenograft mouse models of systemic histiocytosis (SyH) and disseminated HS were established, and examined together with cell lines previously established from localized HS and Langerhans cell histiocytosis (LCH). The chromosomal numbers of the SyH and HS cell lines were abnormal, and their population doubling time and morphological features were comparable. Immunophenotypically, SyH and HS cells were CD204+/E-cadherin+ in vitro and in vivo, like their original tissues. Western blot analysis for E-cadherin revealed an immunopositive band of full-length E-cadherin (120 kDa) in cultured cells of localized HS and LCH but not in disseminated HS and SyH; expression level was weaker in localized HS than in LCH. An immunopositive band of fragmented E-cadherin (45 kDa) was detected in cell lines of disseminated HS and SyH. These results suggest that cultured SyH cells have features that are similar to disseminated HS, including chromosomal aberration, high proliferation activity, weak cell adhesion, and expression of fragmented E-cadherin. Fragmentation of the E-cadherin cell adhesion molecule may be associated with the loss of cell adhesion and increased abilities of invasion and migration of neoplastic cells. The established cell lines and xenograft mouse models will aid in understanding the pathogenesis and developing novel treatments of canine histiocytic proliferative disorders.

Persistent Infection of a Canine Histiocytic Sarcoma Cell Line with Attenuated Canine Distemper Virus Expressing Vasostatin or Granulocyte-Macrophage Colony-Stimulating Factor

Canine histiocytic sarcoma (HS) represents a neoplasia with poor prognosis. Due to the high metastatic rate of HS, there is urgency to improve treatment options and to prevent tumor metastases. Canine distemper virus (CDV) is a single-stranded negative-sense RNA (ssRNA (-)) virus with potentially oncolytic properties. Moreover, vasostatin and granulocyte-macrophage colony-stimulating factor (GM-CSF) are attractive molecules in cancer therapy research because of their anti-angiogenetic properties and potential modulation of the tumor microenvironment. In the present study, an in vitro characterization of two genetically engineered viruses based on the CDV strain Onderstepoort (CDV-Ond), CDV-Ondneon-vasostatin and CDV-Ondneon-GM-CSF was performed. Canine histiocytic sarcoma cells (DH82 cells) were persistently infected with CDV-Ond, CDV-Ondneon, CDV-Ondneon-vasostatin and CDV-Ondneon-GM-CSF and characterized on a molecular and protein level regarding their vasostatin and GM-CSF production. Interestingly, DH82 cells persistently infected with CDV-Ondneon-vasostatin showed a significantly increased number of vasostatin mRNA transcripts. Similarly, DH82 cells persistently infected with CDV-Ondneon-GM-CSF displayed an increased number of GM-CSF mRNA transcripts mirrored on the protein level as confirmed by immunofluorescence and Western blot. In summary, modified CDV-Ond strains expressed GM-CSF and vasostatin, rendering them promising candidates for the improvement of oncolytic virotherapies, which should be further detailed in future in vivo studies.

Prolonged Survival Following Treatment of Histiocytic Sarcoma of the Canine Urinary Bladder

A 9 yr old castrated male miniature schnauzer was diagnosed histopathologically with a mucosal histiocytic sarcoma of the urinary bladder apex, biopsied at the time of surgical cystotomy. Sequential adjuvant chemotherapy, including both lomustine (discontinued because of adverse effects) and then doxorubicin, were employed. A response to both agents was documented. Ultimately, a complete response was achieved following completion of the doxorubicin protocol. A complete response persisted 768 days following diagnosis at last follow-up. Histiocytic sarcoma of the urinary bladder remains a rare diagnosis in veterinary medicine. Only one previous case report is currently published. This case contrasts with the previous case report, which reported a survival of only 2 mo.

Increased tumor-infiltrating lymphocyte density is associated with favorable outcomes in a comparative study of canine histiocytic sarcoma

Histiocytic sarcoma (HS) is a rare and aggressive tumor in humans with no universally agreed standard of care therapy. Spontaneous canine HS exhibits increased prevalence in specific breeds, shares key genetic and biologic similarities with the human disease, and occurs in an immunocompetent setting. Previous data allude to the immunogenicity of this disease in both species, highlighting the potential for their successful treatment with immunotherapy. Quantification of CD3 tumor-infiltrating lymphocytes (TIL) in five cases of human HS revealed variable intra-tumoral T cell infiltration. Due to the paucity of human cases and lack of current model systems in which to appraise associations between anti-tumor immunity and treatment-outcome in HS, we analyzed clinical data and quantified TIL in 18 dogs that were previously diagnosed with localized HS and treated with curative-intent tumor resection with or without adjuvant chemotherapy. As in humans, assessment of TIL in biopsy tissues taken at diagnosis reveal a spectrum of immunologically "cold" to "hot" tumors. Importantly, we show that increased CD3 and granzyme B TIL are positively associated with favorable outcomes in dogs following surgical resection. NanoString transcriptional analyses revealed increased T cell and antigen presentation transcripts associated with prolonged survival in canine pulmonary HS and a decreased tumor immunogenicity profile associated with shorter survivals in splenic HS. Based on these findings, we propose that spontaneous canine HS is an accessible and powerful novel model to study tumor immunology and will provide a unique platform to preclinically appraise the efficacy and tolerability of anti-cancer immunotherapies for HS.

A bitesize introduction to canine hematologic malignancies

Hematologic malignancies are frequently diagnosed in dogs and result in a spectrum of clinical signs associated with specific disease types. The most frequently encountered hematologic tumors in dogs include lymphoma, lymphoid and myeloid leukemias, and mast cell, plasma cell, and histiocytic neoplasias. Coupled with the heterogeneous presentations of the different categories and subtypes of canine hematologic malignancies, outcomes for these tumors are also variable. Considering this, appropriate treatment options range from active surveillance to curative intent approaches harnessing surgical, chemotherapeutic, and radiation-based modalities. The underlying pathology of many of these diseases bears remarkable resemblance to that of the corresponding diagnosis made in human patients. We introduce some of the pathogenic drivers of canine hematologic cancers alongside their clinical presentations. An overview of standard-of-care therapies for each of these diseases is also provided. As comparative oncology gains recognition as a valuable setting in which to investigate the pathogenesis of neoplasia and provide powerful, clinically relevant, immunocompetent models for the evaluation of novel therapies, the number of clinicians and scientists participating in cancer research involving dogs is expected to increase. This review aims at providing an introductory overview of canine hematologic malignancies.

Outcome in dogs with curative-intent treatment of localized primary pulmonary histiocytic sarcoma

Primary pulmonary histiocytic sarcoma (PHS) is a rare form of dendritic cell or macrophage neoplasia originating within the pulmonary parenchyma. There is limited literature describing prognosis in dogs with PHS receiving curative-intent treatment consisting of surgical excision and adjuvant chemotherapy. The primary objective of this study was to report outcomes in dogs with localized PHS treated with standardized local and systemic therapy. A secondary objective was to identify prognostic factors in this population. A multi-institutional retrospective study was performed and medical records including all surgical and histopathologic reports were retrospectively reviewed. For inclusion, dogs were required to have confirmed localized PHS and they must have undergone curative-intent surgery with resection of all gross primary tumour and enlarged tracheobronchial lymph nodes; additionally, they must have received curative-intent treatment with adjuvant single-agent CCNU chemotherapy. Twenty-seven dogs from six veterinary teaching hospitals and five private practices treated from 2008-2019 were included. The overall median survival time was 432 days. Higher CCNU dose was demonstrated to have a negative impact on survival on univariate, but not multivariable, analysis. Factors that were not found to be associated with survival on univariate analysis included body weight, breed, clinical signs at the time of diagnosis, hypoalbuminaemia, tumour size, lung lobe affected, lymph node metastasis, surgical margins and CCNU dose reductions. This study supports a favourable prognosis for dogs diagnosed with localized PHS treated with curative-intent surgery in addition to adjuvant CCNU chemotherapy and suggests that multimodal treatment may be advisable to attempt to prolong survival.

Periarticular histiocytic sarcoma with heart metastasis in a cat

A 4-year-old intact female domestic short-haired cat was referred for recommendations about adjuvant medical treatment 1 month after left forelimb amputation due to periarticular histiocytic sarcoma (HS). At presentation, physical abnormalities were limited to enlarged ipsilateral superficial cervical and axillary lymph nodes. Routine blood analysis, abdominal ultrasound, and thoracic radiology were unremarkable. The cat initially received lomustine without any adverse events. Four weeks later, the cat developed severe acute respiratory distress. Results of thoracic radiographs and transthoracic echocardiographic analysis were suggestive of pulmonary and heart metastasis. Due to the cat's poor clinical condition and prognosis, the owner elected euthanasia, and a necropsy was performed. Based on gross pathology, histopathology, and immunohistochemistry, an HS with nodal, renal, pulmonary, and heart (right auricular and right ventricular) metastases was diagnosed. This case represents the first description of HS with a heart metastasis in a cat, providing further insight into the clinical course and metastatic behavior of this rare malignant neoplasm. Clinicians should be aware of this site of metastasis and consider HS in the list of differential diagnoses for secondary heart tumors in cats.

Diagnosis and treatment of hemophagocytic histiocytic sarcoma in a cat

Case summary

A 7-year-old spayed female domestic shorthair cat was presented for persistent anemia of unknown origin. Splenomegaly was diagnosed through physical examination and abdominal radiographs, and an abdominal ultrasound was performed. The ultrasound showed splenomegaly, as well as one discrete mass in the body of the spleen. A splenectomy was performed and histopathology along with immunohistochemistry for CD18 and CD204 confirmed a diagnosis of hemophagocytic histiocytic sarcoma (HS). Two courses of lomustine (CCNU) chemotherapy were used in this cat along with adjuvant oral prednisolone and iron dextran injections, but the cat eventually succumbed to hepatic failure, presumed to be secondary to metastatic disease.

Relevance and novel information

The clinical pathology results and ultrasonographic studies performed before and after treatment in this cat provide useful preliminary information about the biologic behavior and response to treatment for this rare cancer. This is also the first reported case where both CD18 and CD204 were strongly positive, confirming hemophagocytic HS in a cat.

Immunophenotyping of Nonneoplastic and Neoplastic Histiocytes in Cats and Characterization of a Novel Cell Line Derived From Feline Progressive Histiocytosis

Histiocytic proliferative diseases are rare in cats, and their pathogenesis is poorly understood. In the present study, 25 cases of histiocytic sarcoma (HS) and 6 of feline progressive histiocytosis (FPH) were examined, and survival times were recorded in 19 cases. The immunophenotypes of tumor cells in these cases as well as of nonneoplastic feline histiocytes were characterized using formalin-fixed, paraffin-embedded tissues. An FPH cell line (AS-FPH01) and xenotransplant mouse model of FPH were also established. The median survival time of HS (150 days) was significantly shorter than that of FPH (470 days). Immunohistochemically, nonneoplastic histiocytes were immunopositive for various combinations of Iba-1, HLA-DR, E-cadherin, CD204, CD163, CD208, and MAC387. By immunohistochemistry, dermal interstitial dendritic cells (iDCs) and macrophages were CD204+/E-cadherin-, while epidermal Langerhans cells (LCs) were CD204-/E-cadherin+. Neoplastic cells of 4 FPH and 18 HS were CD204+/E-cadherin- (iDC/macrophage immunophenotype), while 2 FPH and 2 HS were CD204-/E-cadherin+ (LC immunophenotype), and 5 HS were CD204+/E-cadherin+ (LC-like cell immunophenotype). Furthermore, immunohistochemical and western blot analyses of AS-FPH01 cells derived from E-cadherin-negative FPH revealed that cultured cells were immunopositive for both CD204 and E-cadherin in vitro and in vivo. These results indicate that the neoplastic cells of feline HS and FPH were variably positive for iDC/macrophage and LC markers, and their immunophenotype changed in different microenvironments. The novel cell line established in the present study may serve as an experimental model of FPH that will enable further molecular and therapeutic studies on this disease.

Oral histiocytic sarcoma in a cat

CASE SUMMARY

A 15-year-old neutered male domestic shorthair cat presented with a 4-week history of dysphonia and reluctance to chew hard food. Oral examination revealed a mass lesion on the caudal soft palate. Biopsy was performed and histopathology with immunohistochemistry was most consistent with histiocytic sarcoma. CT of the head identified a discrete, left-sided, soft tissue mass lesion cranial to the tonsil with bilaterally symmetrical regional lymph nodes. CT of the thorax was unremarkable. Surgical removal achieved cytoreduction but not complete removal. Adjuvant chemotherapy with lomustine 10 mg (30 mg/m2) was initiated. The patient developed suspected pancreatitis 2-3 weeks postoperatively, so further chemotherapy treatment was discontinued, but supportive treatment with pain relief and appetite stimulants was provided. Three months postoperatively, the patient developed recurrent dysphonia, and oral examination revealed a suspicion of local recurrence. Confirmation of diagnosis (cytopathology or histopathology) was not obtained. Supportive treatment to maintain a good quality of life was continued and the patient was euthanased 6 months after diagnosis owing to progressive disease.

RELEVANCE AND NOVEL INFORMATION

Only a few reports have been published describing histiocytic diseases of cats. To our knowledge, this is the first report of a feline histiocytic sarcoma of the oral cavity. Therefore, histiocytic sarcoma should be considered as a differential diagnosis in feline patients with an oral mass, especially if histopathology suggests a pleomorphic and poorly differentiated sarcoma. Immunohistochemistry for the confirmation of cell line origin would be strongly recommended.

Histiocytic sarcoma in miniature schnauzers: 30 cases

OBJECTIVES

To summarise the clinical presentation and outcomes in a series of miniature schnauzers diagnosed with histiocytic sarcoma.

MATERIALS AND METHODS

Retrospective review of medical records of miniature schnauzers diagnosed with histiocytic sarcoma between 2008 and 2019 at two referral centres in the UK. Signalment, clinical signs at initial presentation, imaging results and clinico- and histopathological findings, treatment type and outcome were recorded. Progression-free survival and overall survival time were calculated.

RESULTS

Thirty dogs were included. Twenty-four of 29 dogs undergoing imaging of the thorax had lung and/or mediastinal involvement. The median overall survival time for dogs that were not euthanased within 3 days of diagnosis was 117 days (range 10 to 790). Three dogs underwent surgery; 13 received treatment with lomustine as a sole therapy - with partial responses documented on imaging in five of six dogs and 11 of 13 showing clinical improvement.

CLINICAL SIGNIFICANCE

Histiocytic sarcoma should be considered as a differential diagnosis for miniature schnauzers with pulmonary masses. Although responses to treatment were common, they were usually short-lived because of the aggressive nature of the disease.

Nimustine Treatment of 11 Cases of Canine Histiocytic Sarcoma

The objective of this retrospective study was to report treatment outcomes in dogs with histiocytic sarcoma (HS) that were treated with nimustine (ACNU). This study evaluated data from 11 dogs including 5 with macroscopic tumors that were treated in the primary setting and 6 that underwent aggressive local therapy while being treated in the adjuvant setting. The median ACNU starting dose was 25 mg/m² (range, 20-30 mg/m²; 3- to 5-wk intervals, 1-8 administrations). The median overall survival in the primary and adjuvant settings was 120 days (median progression-free survival [PFS], 63 days) and 400 days (median PFS, 212 days), respectively. Neutropenia was observed in eight cases (grade 1, n = 1; grade 2, n = 2; grade 3, n = 2; grade 4, n = 3) with nadir neutrophil count at 1 wk after ACNU administration. Mild gastrointestinal toxicity (grade 1-2) was observed in three cases. ACNU was well tolerated and showed a similar outcome to that seen for lomustine, which is a drug commonly used to treat canine HS, in terms of overall survival and PFS in the current study population. Further investigations will need to be undertaken to definitively determine if ACNU is an appropriate alternative to lomustine for the treatment of HS.

Histiocytic Sarcoma and Hemangiosarcoma Update

Histiocytic sarcoma (HS) and hemangiosarcoma (HSA) are uncommon and aggressive neoplasms that develop much more frequently in dogs than in cats. Breed-specific predispositions have been identified for both cancers. The development of novel diagnostics is underway and may aid in earlier diagnosis. Therapeutic approaches to HS and HSA depend on the stage of disease and may include surgery, radiation therapy, and chemotherapy. Such interventions improve outcome; however, aside from a small number of clinical circumstances, both diseases are considered largely incurable. Continued efforts toward the identification of driver mutations and subsequent druggable targets may lead to improvements in long-term prognosis.

Hemipelvic and proximal femoral limb salvage endoprosthesis with tendon ongrowth in a dog

OBJECTIVE

To report the clinical application of a hemipelvic and proximal femoral endoprosthesis for limb salvage.

STUDY DESIGN

Retrospective case report.

ANIMAL

One 5-year-old, neutered female, flat coated retriever with a malignant neoplasia of the left coxofemoral joint.

METHODS

An invasive soft tissue mass (histiocytic sarcoma) with bone lysis of the femoral head and acetabulum was noted on radiographs, computed tomography (CT), and MRI. Custom-designed hemipelvic and proximal femoral endoprostheses were produced from CT images and manufactured with hydroxyapatite coated surfaces to allow tissue integration. The proximal femoral implant allowed tendon ongrowth and muscle attachment. The pelvic implant was anchored to the ilium and ischium with screws, and the femoral implant was cemented. Chemotherapy consisted of lomustine (CCNU).

RESULTS

No evidence of implant loosening or local/thoracic metastases was noted on radiographs or CT at 6 weeks and at 3, 6, 9, and 12 months after surgery. A neurapraxia resolved 14 weeks postoperatively. Intensive rehabilitation was performed. At 12 months, activity was unrestricted with minimal residual lameness. The dog was euthanized at 14 months for metastatic disease.

CONCLUSION

Limb salvage with a hemipelvic and proximal femoral endoprosthesis resulted in limb function and survival for 14 months.

CLINICAL SIGNIFICANCE

Neoplasia involving the bones of the coxofemoral joint traditionally requires hemipelvic resection and pelvic limb amputation. This report provides evidence that limb salvage can result in satisfactory levels of activity.

Primary pulmonary histiocytic sarcoma in dogs: A retrospective analysis of 37 cases (2000-2015)

Primary pulmonary histiocytic sarcoma (PHS) has been reported, but is not well characterized. The aim of this retrospective study was to describe clinical characteristics, characterize prognostic factors and report the outcome of a larger group of dogs with primary PHS. Medical records of dogs diagnosed with primary PHS at 11 institutions were retrospectively reviewed. Thirty-seven dogs were included; 13 received CCNU-based chemotherapy alone, 18 received surgery and adjuvant CCNU-based chemotherapy, 3 received medical management alone and 3 dogs received surgery alone. The overall median progression free survival (PFS) and the median survival (overall survival [OS]) were 197 and 237 days, respectively. Measurable responses were noted in dogs receiving only chemotherapy; however, responses were not durable with PFS (91 days) and OS times (131 days) shorter than overall medians. Dogs that received surgery and chemotherapy had significantly prolonged PFS (276 days, P = 0.001) and OS (374 days, P = 0.001), compared with dogs not receiving surgery. As only three dogs undergoing surgery did not receive chemotherapy, it is not possible to determine the contribution of chemotherapy as an adjuvant to surgery. Dogs without evidence of intra-thoracic metastatic disease were much more likely to undergo surgery (odds ratio = 7.04; P = 0.018). While the presence of metastasis or clinical signs at diagnosis negatively impacted PFS, only the former negatively impacted OS. These data imply that dogs presenting with PHS amenable to surgery (ie, no clinical evidence of metastasis) benefit from surgical intervention; however, the lack of a comparable surgery alone group precludes assessment of the efficacy of post-surgical adjuvant chemotherapy.

Canine sarcomas as a surrogate for the human disease

Pet dogs are becoming increasingly recognized as a population with the potential to inform medical research through their treatment for a variety of maladies by veterinary health professionals. This is the basis of the One Health initiative, supporting the idea of collaboration between human and animal health researchers and clinicians to study spontaneous disease processes and treatment in animals to inform human health. Cancer is a major health burden in pet dogs, accounting for approximately 30% of deaths across breeds. As such, pet dogs with cancer are becoming increasingly recognized as a resource for studying the pharmacology and therapeutic potential of anticancer drugs and therapies under development. This was recently highlighted by a National Academy of Medicine Workshop on Comparative Oncology that took place in mid-2015 (http://www.nap.edu/21830). One component of cancer burden in dogs is their significantly higher incidence of sarcomas as compared to humans. This increased incidence led to canine osteosarcoma being an important component in the development of surgical approaches for osteosarcoma in children. Included in this review of sarcomas in dogs is a description of the incidence, pathology, molecular characteristics and previous translational therapeutic studies associated with these tumors. An understanding of the patho-physiological and molecular characteristics of these naturally occurring canine sarcomas holds great promise for effective incorporation into drug development schemas, for evaluation of target modulation or other pharmacodynamic measures associated with therapeutic response. These data could serve to supplement other preclinical data and bolster clinical investigations in tumor types for which there is a paucity of human patients for clinical trials.

Prior joint disease is associated with increased risk of periarticular histiocytic sarcoma in dogs

Periarticular histiocytic sarcoma (PAHS) is the most common synovial tumour in dogs and is characterized by aggressive local disease with a high rate of distant metastasis. Previously, an association between PAHS and prior joint disease has been demonstrated in the Bernese Mountain Dog breed and suggested in the Rottweiler. We hypothesized that this association would be present in other breeds and investigated this via a retrospective, case-controlled analysis. Cases were dogs diagnosed with PAHS of the stifle or elbow. Controls were age, breed and sex-matched dogs without a diagnosis of histiocytic sarcoma. Diagnosis of prior joint disease was determined based on review of medical records and direct veterinarian and owner communications. Data were evaluated using logistic regression, 2-sampled t tests, and chi-squared analysis. Our study population consisted of 28 cases and 46 controls, including Flat-Coated, Golden and Labrador Retrievers, Rottweilers, English Bulldogs, Shih Tzus, Australian Shepherds, Staffordshire Terriers and mixed breed dogs. Dogs with PAHS were more likely to have prior joint disease in the tumour-affected joint compared with the control population (odds ratio [OR] = 13.42, P < .0001, 95% confidence interval [CI] = 4.33-48.63). A total of 88.2% of dogs with stifle PAHS had prior joint disease in their tumour-affected joint, most commonly cranial cruciate ligament rupture. This study confirms that the previously noted association between prior joint disease and PAHS in Bernese Mountain Dogs also applies to other breeds. Additional studies are needed to further investigate for a causal relationship.

Histiocytic sarcoma in 14 miniature schnauzers - a new breed predisposition?

OBJECTIVES

To describe a series of miniature schnauzers diagnosed with histiocytic sarcoma and assess for possible breed predisposition.

MATERIALS AND METHODS

Medical records of miniature schnauzers with a diagnosis of histiocytic sarcoma between January 2008 and April 2015 were reviewed. Data collected included signalment, body weight, presenting complaint, date of diagnosis, clinicopathologic and diagnostic imaging findings, treatment, therapeutic response, date of death or last follow-up and necropsy findings. Breed predisposition was assessed with odds ratios, using breed-matched dogs without histiocytic sarcoma admitted during the study period as controls. Pedigree analysis was performed for dogs with available registration information.

RESULTS

Fourteen miniature schnauzers were diagnosed with histiocytic sarcoma during the study period, making them over-represented among the hospital population (odds ratio=4·8, P=0·0009). Disease was considered localised in ten dogs and disseminated in four. Of the dogs with localised disease, nine were diagnosed with primary pulmonary histiocytic sarcoma based on the presence of a large pulmonary mass with (n=7) or without (n=2) evidence of intra-thoracic metastasis, and one had gastric histiocytic sarcoma with nodal metastasis. Treatments varied, but an aggressive clinical course was found in most patients. Pedigree analysis revealed a recent common ancestor for a subset of the dogs assessed.

CLINICAL SIGNIFICANCE

Miniature schnauzers were over-represented among dogs with histiocytic sarcoma in this patient population. Pedigree analysis supports an inherited risk factor, which has not previously been suggested in the breed. Primary pulmonary involvement with or without intra-thoracic metastasis was common in this cohort.

Efficacy of dacarbazine as a rescue agent for histiocytic sarcoma in dogs

BACKGROUND

Canine histiocytic sarcoma (HS) is an aggressive neoplasm that is generally associated with a poor prognosis. CCNU is considered first-line medical therapy, although the majority of dogs ultimately develop progressive disease. The objective of this study was to evaluate the efficacy of dacarbazine as a rescue agent for HS.

MATERIALS AND METHODS

Medical records of dogs diagnosed with HS that received at least one dose of dacarbazine were reviewed. Information collected and analyzed included signalment, disease distribution, treatment history, dacarbazine treatments (including dose, interval and total number of cycles), adverse events, and response to treatment.

RESULTS

Seventeen dogs were included, all of which had disseminated or metastatic disease and had received prior treatment with CCNU. Three dogs achieved partial remission for an overall response rate of 17.6%. The overall median event-free survival (EFS) was 21 days. For dogs that experienced an objective response, the EFS was 70 days. Toxicity secondary to dacarbazine was generally mild and self-limiting.

CONCLUSION

In the setting of advanced disease, dacarbazine appears to have modest activity against HS and warrants further investigation.

Chemotherapy for dogs with lymph node metastasis from histiocytic sarcomas

BACKGROUND

Histiocytic sarcomas (HS) frequently metastasise, most commonly to visceral sites, but also to regional lymph nodes. Nodal metastases are associated with a poorer prognosis. This retrospective study aimed to evaluate prognostic factors, including the effect of adjuvant chemotherapy, on survival in dogs with nodal, but not systemic, metastases from HS.

METHODS

Retrospective case series of 12 dogs with histologically diagnosed HS metastatic to lymph nodes treated with surgery with and without adjuvant chemotherapy.

RESULTS

All dogs had histological evidence of metastasis to lymph nodes, with no clinical evidence for metastasis to viscera. Eight dogs that received chemotherapy had a median estimated survival of 219 days (range 77-1638 days); 1- and 2-year estimated survival rates were 37.7%. Median survival time for 4 dogs with nodal metastases that did not receive chemotherapy was 57 days (range 39-136 days) with none alive 1 year after surgery CONCLUSION: Survival for dogs with only regional nodal metastases from HS appeared to be improved by adjuvant chemotherapy.

T Lymphocytes in Histiocytic Sarcomas of Flat-Coated Retriever Dogs

Flat-Coated Retriever dogs are predisposed to the development of histiocytic sarcoma (HS), a poorly differentiated, highly malignant neoplasm. The authors have previously documented a significant lymphocytic infiltrate in such tumors. The objective of this study was to examine the presence and expression of regulatory T cells in HS tumor samples. Forty tumors were included in this study. All tumors were immunolabeled for CD3, CD79a, CD25, CD45RA, and FOXP3. The proportion of positive cells was compared between tumors presenting as a localized primary soft tissue mass (soft tissue origin HS) and disseminated HS affecting viscera, especially the spleen (splenic origin HS). By immunohistochemistry, 95% of infiltrating T cells were positive for Foxp3 in all sections, suggesting the presence of regulatory T cells. The proportion of cells positive for FOXP3 was higher in the tumors arising in soft tissues, whereas the proportion of CD45RA-positive cells was higher in the splenic origin HS. Canine HS has an aggressive clinical behavior and is uniformly fatal. The difference in the proportion of tumor-infiltrating lymphocytes positive for these 2 markers in the 2 locations may represent differences in tumor microenvironment between the 2 sites.

Canine Histiocytic Malignancies-Challenges and Opportunities

Canine histiocytic malignancies (HM) are aggressive tumors that occur with particularly high frequency in certain breeds including Bernese mountain dogs and flat-coated retrievers. Robust diagnosis of HM commonly utilizes immunohistochemical stains that are broadly ineffective on formalin-fixed tissues; thus the diagnosis is often one of exclusion. Clinical outcomes are generally poor, with frequent metastasis and therapeutic failure lowering overall survival at time of diagnosis to an average of less than two months in the majority of published work. The limited understanding of the molecular mechanisms underlying HM has hindered the development of more effective diagnostic modalities and the identification of therapeutic targets. A potential avenue exists for advancing clinical management of canine cancers through extrapolation from a close counterpart in human medicine. Historically, HM have been compared to the rare and understudied subset of human cancers involving the dendritic lineage, such as dendritic cell sarcoma or Langerhans cell sarcoma. Recent data have now thrown into question the cellular origin of HM, suggesting that the disease may originate from the macrophage lineage. This review summarizes existing knowledge of HM from the clinical, histologic and molecular perspectives, and highlights avenues for future research that may aid the development of novel diagnostic and therapeutic approaches. In turn, a more advanced appreciation of the mechanisms underlying HM should clarify their cellular origin and identify appropriate opportunities for synergistic extrapolation between related canine and human cancers.

Clinical effects of vinorelbine administration in the management of various malignant tumor types in dogs: 58 cases (1997-2012)

OBJECTIVE

To evaluate the effectiveness of vinorelbine in the management of various malignant tumor types in dogs.

DESIGN

Retrospective case series.

ANIMALS

58 dogs with malignant tumors, including pulmonary carcinoma (n = 31), histiocytic sarcoma (9), mast cell tumor (5), lymphoma (4), melanoma (2), and 7 other tumor types (1 each).

PROCEDURES

Medical records of dogs treated with vinorelbine from December 1997 to December 2012 were reviewed for data regarding signalment, clinical signs, physical examination findings, clinicopathologic test results, diagnostic imaging results, vinorelbine doses and dose frequency, surgery and radiotherapy details when applicable, other chemotherapeutics administered, and outcomes. Descriptive, comparative, and survival statistics were computed for all dogs and for dogs by histologic subgroup of tumors.

RESULTS

Vinorelbine was administered palliatively to 44 (76%) dogs. One (2%) dog had a complete response for 162 days, 5 (11%) dogs had a partial response for a median duration of 91 days, 19 (43%) dogs had stable disease for a median duration of 68 days, and 19 (43%) dogs developed progressive disease after a median duration of 21 days. Clinical benefit was more difficult to assess in the remaining 14 (24%) dogs that received vinorelbine as an adjuvant treatment. Overall median time to tumor progression was 103 days (range, 5 to 1,533 days).

CONCLUSIONS AND CLINICAL RELEVANCE

Vinorelbine appeared to be effective in the treatment of several tumor types in dogs. Follow-up prospective studies of the clinical benefit of the drug in specific clinical scenarios will be necessary to support this conclusion.

Evaluation of a combination chemotherapy protocol including lomustine and doxorubicin in canine histiocytic sarcoma

OBJECTIVES

To describe a chemotherapy protocol combining lomustine and doxorubicin in canine histiocytic sarcoma, including outcomes and toxicity.

MATERIALS AND METHODS

Retrospective review of case records for dogs with histiocytic sarcoma treated with lomustine and doxorubicin (± cyclophosphamide) alternating every 2 weeks. Data collected included signalment, clinical signs, clinicopathological abnormalities, extent of disease, response, toxicity, time to tumour progression and survival time.

RESULTS

Of 17 dogs, 15 had disseminated or metastatic disease. The median number of chemotherapy cycles (one dose of each drug) received was three; most dogs discontinued therapy due to progressive disease. Dose reductions or delays occurred in 18% of cycles. The overall response rate was 58%, with a median time to tumour progression of 185 (range, 59 to 268) days for responders. The overall median survival time was 185 (18 to 402) days. No significant prognostic factors were identified.

CLINICAL SIGNIFICANCE

The protocol appeared well-tolerated, had some efficacy against canine histiocytic sarcoma in the study population and could be considered as an alternative to single-agent protocols; prospective comparison may be warranted.

The two main forms of histiocytic sarcoma in the predisposed Flatcoated retriever dog display variation in gene expression

Examination of gene functions in specific tumor types improves insight in tumorigenesis and helps design better treatments. Due to the rarity of histiocytic/dendritic cell sarcoma in humans, it is difficult to accrue such knowledge. Therefore, comparative research of these cancers in predisposed dog breeds, such as the Flatcoated retriever, can be of value. Histiocytic sarcoma in the dog can be grouped into a soft tissue- and visceral form. The soft tissue form at first is localized, while the visceral form progresses more quickly to a terminal state, which might be related to variations in gene expression. Microarray analyses were performed on fresh-frozen tissue from Flatcoated retrievers with either soft tissue- or visceral histiocytic sarcoma. Expression differences of ten most significantly differentially expressed genes were validated with quantitative real-time PCR (q PCR) analyses. Q PCR analyses confirmed the significantly aberrant expression of three of the selected genes: C6 was up-regulated; CLEC12A and CCL5 were down-regulated in the visceral histiocytic sarcoma compared to the soft tissue form. The findings of our study indicate that these two forms of histiocytic sarcoma in the dog display a variation in gene expression and warrant analysis of functional changes in the expression of those genes in these rare sarcomas in man.

Phase I dose-escalation study of nimustine in tumor-bearing dogs

Nimustine (ACNU) is an alkylating agent of the nitrosourea and can be an antineoplastic agent in dogs. But, there has been no report on its dose-limiting toxicity (DLT) in dogs. This study was a phase I dose-escalation clinical trial to determine the maximum tolerated dose (MTD) and DLT of ACNU in tumor-bearing dogs. The starting dosage was 25 mg/m(2), and subsequent dosages were administered in increments of 5 mg/m(2) in cohort of 3 dogs. Eight dogs were included, the MTD was determined to be 25 mg/m(2), DLT was neutropenia, and the optimal interval was considered to be 21 days. The data herein provide a basis for the subsequent phase II trial of ACNU in dogs.

Clinical characteristics and prognostic factors in dogs with histiocytic sarcomas in Japan

Canine histiocytic sarcoma (HS) is a rare neoplasm that originates from dendritic cells or macrophages, and there have been a number of cases experienced in Japan. To identify the characteristics and prognostic variables that determine outcome in dogs with HS in Japan, medical records of 73 dogs with HS were retrospectively analyzed. Signalment, clinical signs, complete blood count (CBC), blood chemistry profiles, treatment, response to treatment and overall survival (OS) were analyzed. Diagnosis of HS was determined histologically in 44 cases and cytologically in 29 cases. The most frequently diagnosed breeds were Flat-Coated Retrievers (n=16, odds ratio [OR] 62.0), Pembroke Welsh corgis (n=15, OR 9.7) and Bernese Mountain dogs (n=14, OR 45.0). Median survival time for all dogs in this study was 43 days. In the dogs that received no treatment or only symptomatic treatment, the median OS was 12 days (range 2–254 days) compared with that of dogs that received surgical treatment and/or chemotherapy (85 days, range 4–360 days). Univariate analysis identified anemia, thrombocytopenia, hypoalbuminemia, hypoproteinemia and not receiving antitumor treatment (chemotherapy and/or surgery) as factors significantly associated with shorter OS. Multivariate analysis confirmed that platelet counts, localized/disseminated lesional pattern and whether the dog received antitumor treatment were significantly predictive of survival.

Pulmonary histiocytic sarcoma in a rabbit

An approximately 8-year-old male castrated Dutch rabbit was evaluated for a 6-day history of respiratory signs, which began as sneezing and progressed to tachypnea with anorexia. On physical examination, tachypnea and pale mucous membranes were noted. Thoracic radiographs revealed a soft tissue pulmonary mass, fine-needle aspirates of which confirmed a neoplasia with malignant features suspicious for a histiocytic sarcoma. The rabbit was discharged and due to a rapidly deteriorating condition, the owner declined chemotherapy with Lomustine and elected euthanasia of the rabbit. The affected lung was submitted for histopathology. Histologic sections of the lung were characterized by clusters of histiocytic cells and multinucleated giant cells with occasional invasion of blood and lymphatic vessels. The histologic diagnosis was histiocytic sarcoma. To the authors' knowledge, this is the first case report of histiocytic sarcoma in a rabbit. Based on the clinical and radiologic findings in this case, histiocytic sarcoma should be included in the list of differentials for rabbits presenting with respiratory signs and evidence of a pulmonary mass.

Histologic and immunohistochemical review of splenic fibrohistiocytic nodules in dogs

BACKGROUND

Splenic fibrohistiocytic nodules (SFHN) are commonly diagnosed. It is suspected that these represent a heterogeneous group of malignant and nonmalignant diseases, separation of which could improve the ability of clinicians to prognosticate for dogs.

HYPOTHESIS/OBJECTIVES

Immunohistochemistry will differentiate histologic diagnoses within the group of SFHN; survival after splenectomy is associated with those histologic types.

ANIMALS

Thirty-two dogs with SFHN treated by or under direction from veterinary oncologists.

METHODS

Retrospective case record analysis from dogs followed from splenectomy until death. Clinical, histopathologic, and immunohistochemistry data analyzed for an association with survival time.

RESULTS

Thirty-two dogs had SFHN; grade 1 (2 dogs), grade 2 (9 dogs), and grade 3 (lymphoid percentage <40%; 21 dogs). Twenty-two dogs died, 10 were censored (9 alive median of 883 days after splenectomy). Median overall survival was 387 days, and grade 3 SFHN was negatively [corrected] associated with survival time as previously reported (P < .001). Of 31 available samples, dogs had diseases reclassified as nodular hyperplasia (13; 8 complex, 5 lymphoid including 2 marginal zone), lymphoma (4; 2 marginal zone lymphoma, 1 high grade B-cell lymphoma, and 1 marginal zone transitional to high grade B-cell lymphoma), 8 stromal sarcomas, and 6 histiocytic sarcomas. Dogs with histiocytic sarcoma had worse survival (median 74 days) than dogs with other diseases.

CONCLUSIONS AND CLINICAL IMPORTANCE

Splenic histiocytic sarcoma is an aggressive disease; however, some dogs with stromal sarcomas had long survival times. The term SFHN is no longer warranted for this group of disorders.

Evaluation and comparison of outcomes in dogs with periarticular and nonperiarticular histiocytic sarcoma

OBJECTIVE

To evaluate and compare the outcomes of dogs with periarticular histiocytic sarcoma (PAHS) and histiocytic sarcoma of other anatomic locations (non-PAHS) and identify factors associated with outcome for dogs with PAHS.

DESIGN

Retrospective cohort study.

ANIMALS

19 dogs with PAHS and 31 dogs with non-PAHS.

PROCEDURES

Medical records of dogs with histiocytic sarcoma that underwent definitive local treatment (surgery or radiation), chemotherapy, or a combination of these were reviewed. Patient signalment, clinical signs, staging test results, clinicopathologic data, type of treatment, response, and outcome were collected, and potential risk factors in dogs with PAHS were identified and analyzed for an association with outcome.

RESULTS

Dogs with PAHS lived significantly longer than did dogs with non-PAHS, with an overall median survival times of 391 (range, 48 to 980) and 128 (range, 14 to 918) days, respectively, despite the presence of suspected metastasis at diagnosis in 13 of 19 dogs with PAHS. Dogs with PAHS without evidence of metastasis at diagnosis lived significantly longer than did dogs with PAHS with evidence of metastasis, with median survival times of 980 (range, 83 to 980) and 253 (range, 48 to 441) days, respectively. Administration of prednisone in dogs with PAHS was associated with a significantly shorter time to tumor progression (TTP) and increased risk of tumor progression and death.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that dogs with PAHS may have a favorable outcome independent of metastatic status when treated with chemotherapy or aggressive multimodal treatment. The concurrent administration of prednisone may be a negative predictive factor for survival time and TTP in dogs with PAHS.

Phase II clinical evaluation of lomustine chemotherapy for feline vaccine-associated sarcoma

Treatment of feline vaccine-associated sarcoma (VAS) is challenging, in part due to the high likelihood of tumour recurrence despite aggressive local therapy. Lomustine is potentially an attractive agent to add to the current treatment armamentarium. In this de-escalating phase I/II prospective trial, 28 cats with measurable VAS were treated at target dosages of 38-60 mg m(-2) every 3 weeks until disease progression. The overall response rate was 25%, with a median progression-free survival and median duration of response of 60.5 and 82.5 days, respectively. Haematologic toxicity, specifically cumulative neutropenia, was significant, and dose reductions and treatment delays were common. Although these data support further investigation of lomustine for the treatment of VAS, safe, multidosing protocols must first be determined.

Bisphosphonates significantly increase the activity of doxorubicin or vincristine against canine malignant histiocytosis cells

Canine malignant histiocytosis (MH) is an aggressive neoplasm of macrophages and dendritic cells. It carries a poor prognosis because of the development of widespread metastasis and poor sensitivity to chemotherapy. Thus, there is a large need for new treatments for MH. We hypothesized that bisphosphonates might be useful to increase the effectiveness of cytotoxic chemotherapy against MH. To address this question, we conducted in vitro screening studies using MH cell lines and a panel of 6 chemotherapy and 5 bisphosphonate drugs. The combination of clodronate with vincristine was found to elicit synergistic killing which was associated with a significant increase in cell cycle arrest. Second, zoledronate combined with doxorubicin also significantly increased cell killing. Zoledronate significantly increased the uptake of doxorubicin by MH cells. On the basis of these findings, we conclude that certain bisphosphonate drugs may increase the overall effectiveness of chemotherapy for MH in dogs.

Evaluation of serum ferritin as a tumor marker for canine histiocytic sarcoma

BACKGROUND

Canine histiocytic sarcoma (HS) is an aggressive malignancy. Hyperferritinemia has been documented in dogs with HS and could serve as a tumor marker aiding in diagnosis and treatment. In people, hyperferritinemia is found in inflammatory diseases, liver disease, and hemolysis, and thus may occur in dogs with these conditions.

OBJECTIVE

To determine if serum ferritin concentration is a tumor marker for canine HS.

ANIMALS

Dogs with HS (18), inflammatory diseases (20), liver disease (24), immune-mediated hemolytic anemia (IMHA) (15), and lymphoma (23).

METHODS

Prospective, observational, cohort study: Serum ferritin concentration was measured at initial diagnosis. Parametric methods were used to compare mean log ferritin concentrations among disease categories. Receiver-operating characteristic curves and likelihood ratios were used to evaluate serum ferritin concentration as a tumor marker.

RESULTS

Varying proportions of dogs with IMHA (94%), HS (89%), liver disease (79%), lymphoma (65%), and inflammatory diseases (40%) had hyperferritinemia. Dogs with IMHA had significantly higher mean ferritin concentration than dogs in all other categories. Dogs with HS had significantly higher mean ferritin concentration than those in the inflammatory disease and lymphoma categories. Mean serum ferritin concentration was not significantly different between dogs with HS and those with liver disease. Decision thresholds were determined to distinguish IMHA and HS from the other diseases associated with hyperferritinemia.

CONCLUSION

Hyperferritinemia is common in dogs with HS and, after IMHA is ruled out, the degree of hyperferritinemia may be useful in differentiating dogs with HS from dogs with inflammatory diseases, liver disease, and lymphoma.