Treatment of T cell lymphoma in dogs

Free circulating versus extracellular vesicle-associated microRNA expression in canine T-cell lymphoma

Introduction

Canine lymphoma (cL) is one of the most frequent cancers in dogs. The T-cell lymphoma (TcL) is not the most common phenotype but presents an aggressive behavior. MicroRNAs (miRNAs), are small, single-stranded, non-coding RNA molecules which can circulate freely in blood or be associated with extracellular vesicles (EVs). The dysregulation of certain miRNAs has been identified in numerous types of human cancers and they have been largely investigated as possible tumors biomarkers in human medicine, while research in veterinary oncology is still scarce. The aim of this study was to compare the expression patterns of free circulating and EV-associated miRNAs in dogs with T-cell lymhoma (TcL) and healthy dogs.

Methods

Eight dogs with TcL were selected as the lymphoma group (LG) and eight dogs were included as controls (Ctrl). Plasma samples were collected at the time of the diagnosis and EVs isolated with ultracentrifugation. miRNAs were extracted from both the circulating EVs and the plasma supernatant, obtaining EV-associated and free-miRNAs. Quantitative real-time PCR was performed to analyze the expression of 88 target miRNAs.

Results

Ten and seven differentially expressed miRNAs between LG and Ctrl were detected in EV-associated and free-miRNAs, respectively. Among EV-associated and free-miRNAs, only has-miR-222-3p was overexpressed in both conditions.

Discussion

All the differentially expressed miRNAs detected in this study, have been already described as dysregulated in other human or canine cancers. The EV-associated miRNAs, which appear to be more stable and better conserved than free-miRNAs, could be investigated in further larger studies to better assess their use as possible biomarkers for TcL.

Characterization of CD3+/CD20+ canine large-cell lymphoma

Immunophenotyping of canine large-cell lymphoma (LCL) for B-cell and T-cell surface antigens is commonly performed to better predict the clinical outcome. Expression of surface antigen CD3 is associated with T-cell malignancies; surface antigen CD20 is expressed on B cells. However, a small subset of canine LCLs expresses both CD3 and CD20 (CD3+/CD20+); this form of lymphoma remains poorly defined at the molecular level. In a retrospective study, we aimed to better characterize immunophenotypic properties and antigen receptor clonality of CD3+/CD20+ LCL. We selected formalin-fixed, paraffin-embedded tissues from 10 cases of CD3+/CD20+ LCL and breed-matched controls of peripheral large T-cell lymphoma (PTCL) and diffuse large B-cell lymphoma (DLBCL). Using PCR for antigen receptor rearrangement (PARR), we identified monoclonal T-cell receptor gamma (TCRγ) rearrangements in all CD3+/CD20+ cases. Three of 10 cases had monoclonal rearrangements in the immunoglobulin heavy chain (IgH), supportive of cross-lineage rearrangement. There was no significant difference in the frequency of antigen receptor rearrangement between CD3+/CD20+ and PTCL cases. In comparison with DLBCL, CD3+/CD20+ LCL had TCRγ rearrangement more frequently and IgH rearrangement less frequently, respectively. Immunolabeling of the B-cell marker PAX5 occurred less frequently in all CD3+/CD20+ LCL cases compared to the DLBCL controls. Immunolabeling for BCL-2 was robust, regardless of immunophenotype. Nuclear Ki67 positivity was variable in CD3+/CD20+ cases, indicating a heterogeneity in proliferation. Overall, cases of canine CD3+/CD20+ LCL had properties similar to PTCL, suggesting a similar histogenesis of these 2 subsets.

T-cell lymphoma involving the rectum of a dog

A mediastinal mass was diagnosed in a 7-year-4-month-old neutered female mixed breed dog following a 3-week history of lethargy, hyporexia and pyrexia. Bi-cavitary imaging, needle aspirate cytology and flow cytometry confirmed WHO clinical stage IVb, intermediate to large T-cell lymphoma involving the mediastinum, liver and spleen. The dog initially responded to a multidrug chemotherapy protocol but clinical deterioration occurred 3 months later. The dog presented with anorexia, vomiting and diarrhoea, associated with marked faecal tenesmus and haematochezia, initially believed by the primary care practitioner to be related to chemotherapy toxicity. However, rectal examination revealed multiple sessile and pedunculated masses. Further diagnostic imaging, cytology and flow cytometry confirmed progressive disease, including T-cell lymphoma of the rectum. Histology and immunohistochemistry confirmed an infiltrate of intermediate-sized CD3-positive neoplastic cells that expanded the rectal mucosa. Rectal lymphoma is uncommon in dogs and previous cases have been B cell in origin. In this report we describe the clinical presentation and macro- and microscopic findings of a case of canine T-cell lymphoma involving the rectum.

Significant increase in MIC-A and MIC-B and soluble MIC-A and MIC-B in canine lymphomas

Non-Hodkin's lymphoma (NHL) is the most frequent hematologic malignancy in humans and dogs. NKG2D is one of the most critical receptors on NK cells, recognizing their natural ligands on malignant cells such as A and B major histocompatibility complex-related proteins (MIC-A and MIC-B). Soluble molecules (sMIC-A and sMIC-B) can interfere with immune synapsis between NK cells and tumor cells, impeding NK cytotoxicity. The main objectives of this study were to analyze, in dogs with diffuse large B cell lymphoma, NK cell lymphoma, and reactive lymphadenopathies, the role of NK cells, their activating receptors NKG2D and NKp46, and their ligands MIC-A and MIC-B, as well as soluble molecules sMIC-A and sMIC-B. Thirty-six dogs with a possible diagnosis of NHL and eight healthy dogs were studied. NHL was diagnosed in 28 (78 %) dogs; in the other 8 (22 %), reactive lymphadenopathies were present. Most of the lymphomas corresponded to B cell NHL (82 %). The most predominant subtype was diffuse large B cell lymphoma (21, 71.5 %), followed by five cases (18 %) that were Non-B Non-T lymphomas (presumably NK cell lymphomas) and other B cell lymphomas (3, 10.5%). There were no cases of T cell NHL. MIC-A was positive in 7 of 27 (26 %) cases of NHL, and MIC-B in 20 of 27 (74 %) NHL. In non-malignant lymphadenopathies, three (37.5 %) dogs were positive for MIC-A, and five (62.5 %) expressed MIC-B. Dogs with lymphoma had higher numbers of NK cells than eight healthy dogs. In 15 dogs (12 cases with NHL and three cases with reactive adenopathies) and eight controls, there were no differences in the number of NK cells expressing NKP46 and NKG2D. NHL dogs had higher values of sMIC-A and sMIC-B. B-cell and NK cell lymphomas correspond to 86 % and 14 % of all canine lymphomas. MIC-A, MIC-B, and sMIC-A and sMIC-B were increased in canine lymphomas.

MUM-1 in canine lymphoma: A pilot study

Expression of interferon regulatory factor 4 (IRF4)/multiple myeloma oncogene-1 (MUM1) in peripheral T-cell lymphoma (PTCL) in people is associated with a poorer survival outcome compared to cases of PTCL lacking MUM1 expression. The aim of this study was to determine whether MUM1 is expressed in canine peripheral T-cell lymphoma not otherwise specified (PTCL-NOS). For comparison, the presence of MUM1 antigen was also investigated in canine diffuse large B cell lymphoma (DLBCL). Nine cases of PTCL-NOS and 9 cases of DLBCL diagnosed by a commercial veterinary diagnostic laboratory were selected. Positive immunohistochemical labeling for MUM1 was observed in PTCL-NOS (2 out of 9 cases) and DLBCL (3 out of 9 cases). These findings suggest that a subset of neoplastic T and B lymphocytes can express MUM1. The role of MUM1 in the biological behavior and outcome of canine lymphoma (CL) requires further investigation on a larger number of cases.

Epigenetic Alterations in Canine Malignant Lymphoma: Future and Clinical Outcomes

Canine malignant lymphoma is a common neoplasia in dogs, and some studies have used dogs as a research model for molecular mechanisms of lymphomas in humans. In two species, chemotherapy is the treatment of choice, but the resistance to conventional anticancer drugs is frequent. The knowledge of molecular mechanisms of development and progression of neoplasia has expanded in recent years, and the underlying epigenetic mechanisms are increasingly well known. These studies open up new ways of discovering therapeutic biomarkers. Histone deacetylases and demethylase inhibitors could be a future treatment for canine lymphoma, and the use of microRNAs as diagnosis and prognosis biomarkers is getting closer. This review summarises the epigenetic mechanisms underlying canine lymphoma and their possible application as treatment and biomarkers, both prognostic and diagnostic.

T-cell lymphoma in a Himalayan black bear in China

A 12-y-old Himalayan black bear suddenly developed depression, anorexia, cough, and dyspnea and died at the Ordos Zoo, China. At autopsy, the mesenteric and cranial mediastinal lymph nodes (LNs) were enlarged; the largest cranial mediastinal LN was ~13 cm in diameter. Scattered-to-diffuse, rounded-or-oval, gray, firm 1-6-mm nodules were observed on the surfaces of the spleen, liver, lungs, and small intestine. Histologically, the enlarged cranial mediastinal and mesenteric LNs, spleen, small intestine, lungs, and liver contained dense populations of neoplastic lymphoid cells (NLCs). The NLCs were round-or-oval with small amounts of mildly eosinophilic cytoplasm and round-or-oval hyperchromatic nuclei with indistinct nucleoli; the mitotic count was 55 in 2.37 mm2. Immunohistochemically, cell membranes and the cytoplasm of NLCs were CD3+, CD79a-, CD20-, CD15-, CD30-, and CD45RA-; hence, the NLCs were derived from T lymphocytes. To our knowledge, T-cell lymphoma has not been reported previously in a Himalayan black bear.

Randomised trial evaluating chemotherapy alone or chemotherapy and a novel monoclonal antibody for canine T-cell lymphoma: A multicentre US study

Background

Canine peripheral nodal T-cell lymphoma is considered chemotherapy resistant and carries a relatively poor prognosis. Prospective evaluations reporting the impact of chemotherapy on progression-free survival (PFS) and overall survival time for dogs with T-cell lymphoma are lacking. This study examined the impact of L-CHOP (L-asparaginase, doxorubicin, cyclophosphamide, vincristine, prednisone) chemotherapy or L-CHOP in combination with AT-005, a US Department of Agriculture-licensed caninised monoclonal antibody, on PFS and response rates in dogs with clinical intermediate- and high-grade peripheral nodal T-cell lymphoma.

Methods

A prospective, randomised, placebo-controlled, investigator- and owner-blinded, multicentre study was completed. All dogs received a 19-week L-CHOP chemotherapy protocol with randomisation (1:1) into placebo or AT-005 groups. Response was evaluated via the Veterinary Cooperative Oncology Group criteria for canine lymphoma.

Results

Forty-nine dogs were enrolled (25 received placebo and 24 received AT-005). Most demographic factors were similar between the two groups, with the exception that more dogs with stage IV and V disease were treated with AT-005 (34% vs. 8%; p = 0.03). Median PFS was 103 days (95% confidence interval [CI], 56-118) in the placebo group versus 64 days (95% CI, 36-118) in the AT-005 group. The overall response rate (ORR) for all dogs was 98% (48 of 49); complete response rate in the placebo group (64%) was not different from the AT-005 group (67%).

Conclusions

To the best of the authors' knowledge, this is the first prospective study to document that treatment with L-CHOP chemotherapy, with or without AT-005, may result in a high ORR, but relatively brief PFS in dogs with clinical intermediate- and high-grade T-cell lymphoma.

Do socioeconomic factors impact management of suspected canine multicentric lymphoma in UK first opinion practice?

BACKGROUND

This study aimed to describe the management of cases of suspected and confirmed canine multicentric lymphoma (ML) in first opinion practice (FOP) and investigate whether socioeconomic factors are associated with initial management.

METHODS

Clinical narratives from electronic health records collected by the Small Animal Veterinary Surveillance Network (SAVSNET) were searched to identify dogs with peripheral lymphadenomegaly in which ML was the major differential. Cases were grouped as either ML confirmed (ML-C) or ML suspected but not confirmed (ML-S). Associations between initial management and socioeconomic factors were assessed via multivariable logistic regression.

RESULTS

Two hundred and sixty-four cases with ML-C and 410 with ML-S were identified. There was an increased probability that owners of ML-C cases resided in less deprived areas. Moreover, a diagnosis was made more commonly in insured dogs. Only insured pets were more likely to be treated with chemotherapy following diagnosis. The majority of dogs in both groups were treated with corticosteroids alone (ML-S, n = 256/410; ML-C, n = 123/264). A small minority were referred (n = 30/674).

CONCLUSION

Socioeconomic inequalities appear to be associated with the diagnosis and management of dogs with suspected or confirmed ML in FOP. Most dogs with suspected multicentric lymphoma (in the UK) are managed in FOP (n = 644/674). Consequently, expanding the knowledge base relevant to this setting offers an opportunity to improve the management of canine lymphoma.

Prognostic indicators for naïve canine non-indolent T-cell lymphoma treated with combination lomustine, vincristine, procarbazine and prednisolone chemotherapy

Lomustine, vincristine, procarbazine and prednisolone (LOPP) chemotherapy has been suggested to be an effective treatment for dogs with naïve non-indolent T-cell lymphoma (TCL). Studies evaluating prognostic factors for dogs with TCL treated with LOPP chemotherapy are lacking. The aim of this retrospective study was to assess potential prognostic factors for canine naïve non-indolent TCL treated with the LOPP protocol. This was a retrospective cohort study of naïve non-indolent TCL treated with the LOPP chemotherapy protocol at a single specialty veterinary oncology clinic. Sixty-seven dogs met the inclusion criteria. The outcomes assessed included progression free survival (PFS), overall survival time (OST) and duration of complete response (DCR). The overall median PFS was 118 days (range 7-2302 days). The median OST was 202 days (range 8-2302 days). The overall median DCR was 316 days (range 38-2261 days). Number of treatments administered (p < .0001), multicentric disease (p = .044) and the presence of hypercalcaemia (p = .006) were prognostic indicators for PFS. Increasing number of treatments (p < .0001) and age (p = .0088) were prognostic indicators for OST. To our knowledge, this is the first study to describe hypercalcaemia as a positive prognostic indicator of PFS for TCL treated with LOPP chemotherapy. LOPP chemotherapy can be considered as a first-line treatment protocol against naïve hypercalcaemic non-indolent TCL.

Histopathological and immunohistochemical characterization of testicular T-cell lymphoma in a dog

Canine lymphoma is the most common neoplasm of the hematopoietic system with the most frequently diagnosed malignancy. Also, dogs affected by T-cell lymphoma displayed a lower rate of complete chemotherapy response and have a high risk of death in the early stage of the disease. A 5-year-old male mixed dog was presented to the Small Animal Hospital, School of Veterinary Medicine, Shiraz University, Shiraz, Iran with a history of left testicle swelling for four months. The testicle had approximately 13.00×10.00 cm size with a greyish-white cut surface. Histopathologically, the testicular tissue was infiltrated by neoplastic cells as only a few degenerated seminiferous tubules have remained. The neoplastic cells were round to oval with pleomorphic nuclei and single or multiple prominent nucleoli. Immunohistochemical analysis revealed positive and negative immunoreactivity for CD3 and CD20, respectively. According to histopathological and immunohistochemical features, the tumor was concluded as a testicular T-cell lymphoma. It seems that recognition of lymphoma type could be helpful for clinicians therapeutic protocols.

Toxicity of cytarabine constant rate infusion in dogs with high-grade non-Hodgkin lymphoma with bone marrow or central nervous system involvement

OBJECTIVE

Cytarabine, a cell-cycle phase-specific antimetabolite, has been reported to improve outcomes in dogs with bone marrow (BM) or central nervous system (CNS) lymphoma involvement receiving combination chemotherapy. The objective of this study was to evaluate the incidence and severity of toxicity of cytarabine constant rate infusion (CRI) in dogs with high-grade non-Hodgkin lymphoma.

METHODS

Medical records of canine lymphoma patients with confirmed or suspected BM (group 1) or CNS (group 2) involvement, treated with a modified cyclophosphamide, epirubicin, vincristine and prednisolone protocol, including a single dose of cytarabine given as CRI, were reviewed and adverse events graded.

RESULTS

Twenty-six dogs were included. Gastrointestinal toxicity occurred in 17 dogs (65.3%), with 5 (19.2%) experiencing grade III or IV toxicity. Neutropenia occurred in nine dogs (34.6%), but was grade I or II in most cases. Three dogs (11.5%) had thrombocytopenia: one grade III and two grade IV. Four dogs (15.3%) experienced increases in alanine amino transferase: one each grade I and II and two grade III. Five dogs (19.2%) required hospitalisation to manage toxicity after completing cytarabine CRI, and haematological toxicity resulted in treatment delays in five dogs (median delay of 4 days, range: 3-7 days).

CONCLUSION

Our findings suggest that gastrointestinal toxicity should be expected in lymphoma patients undergoing cytarabine CRI.

A Retrospective Study of Multi-agent Chemotherapy including either Cyclophosphamide or Lomustine as Initial Therapy for Canine High-grade T-cell Lymphoma (2011-2017)

Multi-agent chemotherapy (vincristine, epirubicin and prednisolone) including either cyclophosphamide (CEOP) or lomustine (LEOP) was given as first-line chemotherapy to treatment-naïve canine lymphoma patients with measurable, high grade T-cell lymphoma (HGTCL). All patients responded to either CEOP or LEOP. Toxicity was typical of multi-agent chemotherapy protocols and 25% of dogs receiving lomustine exhibited mild-to-moderate ALT elevation and 29% grade 3 or 4 neutropenia. Median progression-free survival (100 versus 269 days) and overall survival (155 versus 327 days) were significantly higher in patients receiving LEOP compared to CEOP. Overall survival was improved for patients receiving LEOP compared to those receiving CEOP followed by lomustine-based rescue therapy. The results of this retrospective study support further evaluation of lomustine as part of first-line, multi-agent therapy for patients with HGTCL.

T cell-lymphoma in the eyelid of a 9-year-old English Setter

BACKGROUND

Eyelid tumours are frequently found in dogs, most of these being benign. In case of an ulcerating eyelid tumour, malignancy must be considered. We report a unique case of a low-grade peripheral T-cell lymphoma in the eyelid of a 9-year-old English Setter.

CASE PRESENTATION

A 9-year-old Setter presented with a 6-month history of an eyelid ulcer. A malignant eyelid neoplasm was suspected, and the lesion was surgically excised. No other treatment was applied, and 19 months after excision the dog was still well. Histopathology revealed a diffuse lymphocytic infiltrate in the eyelid skin. Ulceration of the epithelium was seen, and the underlying tumour was composed of round and poorly demarcated pleomorphic tumour cells. The cytoplasm was pale and the nuclei heterogeneous. Numerous mitoses were present. The tumour cells stained strongly for CD3. The final diagnosis was a peripheral T-cell lymphoma not otherwise specified (NOS).

CONCLUSIONS

This is the first described case of a solitary T-cell lymphoma NOS in the haired eyelid skin in a dog. Lymphoma should be considered in case of a persistent eyelid ulcer and a biopsy should be performed. T-cell lymphoma is generally an aggressive disease; however, indolent cases are well known, and as this case shows, complete excision of a solitary T-cell lymphoma can be curable. Canine cutaneous epitheliotropic T-cell lymphoma is an important differential diagnosis, which must be recognized as the prognosis is very poor and systemic treatment is mandatory. The sub-classification of canine lymphoma is not complete, and further studies are needed to identify lymphoma subgroups and provide treatment guidelines.

Evaluation of a multi-agent chemotherapy protocol combining lomustine, procarbazine and prednisolone (LPP) for the treatment of relapsed canine non-Hodgkin high-grade lymphomas

The standard of care treatment for canine lymphoma is multi-agent chemotherapy containing prednisolone, cyclophosphamide, vincristine and an anthracycline such as doxorubicin (CHOP) or epirubicin (CEOP). Lomustine, vincristine, procarbazine, and prednisone (LOPP) has been evaluated as a rescue, with encouraging results; however, resistance to vincristine is likely in patients relapsing on CHOP/CEOP, and this agent may enhance LOPP toxicity without improving efficacy. The aim of this study was to evaluate responses to a modified-LOPP protocol that does not include vincristine (LPP) and is administered on a 21-day cycle. Medical records of dogs with high-grade multicentric lymphoma from 2012 to 2017 were reviewed. Dogs with relapsed lymphoma that received LPP as a rescue protocol were enrolled. Response, time from initiation to discontinuation (TTD) and toxicity of LPP were assessed. Forty-one dogs were included. Twenty-five dogs (61%) responded to LPP including 12 complete responses (CR) and 13 partial responses (PR). Responders had a significantly longer TTD (P < .001) compared to non-responders with 84 days for CR and 58 days for PR. Neutropenia was documented in 20 dogs (57%): 12 grade I to II, 8 grade III to IV. Thrombocytopenia was infrequent (20%): 5 grade I to II, 2 grade III to IV. Twelve dogs developed gastrointestinal toxicity (30%): 10 grade I to II and 2 grade III. Nineteen dogs had elevated ALT (59%): 9 grade I to II, 10 grade III to IV. Treatment was discontinued due to toxicity in 8 dogs (19%). The LPP protocol shows acceptable efficacy and toxicity-profile and minimizes in-hospital procedures.