Assessment of biomarkers influencing treatment success on small intestinal lymphoma in dogs

Comparison of chemotherapy outcomes between normal and high serum cortisol concentration in dogs with lymphoma

BACKGROUND

Increased serum cortisol (COR) concentrations may induce glucocorticoid resistance by down-regulation of glucocorticoid receptor (GCR), resulting in decreased chemotherapy efficacy in dogs with lymphoma.

HYPOTHESIS

Investigate the relationship between serum COR concentrations and chemotherapy outcomes in dogs with lymphoma.

ANIMALS

Thirty client-owned dogs with lymphoma, with serum COR concentration measured using serum samples collected at diagnosis.

METHODS

Retrospective study. Dogs were divided into 2 groups based on serum COR concentrations: a normal group (n = 16) with COR concentrations <6 μg/dL and a high group (14) with COR concentrations ≥6 μg/dL. We compared signalment, clinical signs, stage, type of lymphoma, adrenal gland size, alkaline phosphatase (ALP) activity, response to chemotherapy, progression-free survival (PFS), overall survival (OS), and rate of P-glycoprotein (P-gp)- and GCR-positive cells between the 2 groups.

RESULTS

No significant differences were found in the demographic characteristics between the 2 groups. However, the high COR group exhibited a significantly lower response to chemotherapy, PFS, and OS compared with the normal COR group. Serum ALP activity was significantly higher in the high COR group than in the normal COR group. Adrenal gland size was also significantly larger in the high COR group. Although no significant differences were found in the rate of P-gp-positive cells between the 2 groups, the rate of GCR-positive cells was significantly lower in the high COR group.

CONCLUSIONS AND CLINICAL IMPORTANCE

Our data suggests that measurement of serum COR concentrations may serve as a potential prognostic factor and evaluation index.

Mitotic activity: A systematic literature review of the assessment methodology and prognostic value in canine tumors

One of the most relevant prognostic indices for tumors is cellular proliferation, which is most commonly measured by the mitotic activity in routine tumor sections. The goal of this systematic review was to analyze the methods and prognostic relevance of histologically measuring mitotic activity that have been reported for canine tumors in the literature. A total of 137 articles that correlated the mitotic activity in canine tumors with patient outcome were identified through a systematic (PubMed and Scopus) and nonsystematic (Google Scholar) literature search and eligibility screening process. Mitotic activity methods encompassed the mitotic count (MC, number of mitotic figures per tumor area) in 126 studies, presumably the MC (method not specified) in 6 studies, and the mitotic index (MI, number of mitotic figures per number of tumor cells) in 5 studies. A particularly high risk of bias was identified based on the available details of the MC methods and statistical analyses, which often did not quantify the prognostic discriminative ability of the MC and only reported P values. A significant association of the MC with survival was found in 72 of 109 (66%) studies. However, survival was evaluated by at least 3 studies in only 7 tumor types/groups, of which a prognostic relevance is apparent for mast cell tumors of the skin, cutaneous melanoma, and soft tissue tumor of the skin and subcutis. None of the studies using the MI found a prognostic relevance. This review highlights the need for more studies with standardized methods and appropriate analysis of the discriminative ability to prove the prognostic value of the MC and MI in various tumor types. Future studies are needed to evaluate the influence of the performance of individual pathologists on the appropriateness of prognostic thresholds and investigate methods to improve interobserver reproducibility.

Hypoxia-targeting therapy for intestinal T-cell lymphoma in dogs: Preclinical study using 3D in vitro models

The transcription factor hypoxia-inducible factor 1α (HIF-1α) is activated in response to oxygen deficiency, and is expressed in several cancers under intratumoral hypoxic stress that arises during pathogenic processes. Hypoxic stimulation enhanced the growth potential of canine lymphoma cells by activating the HIF-1α signalling pathway in a previously reported study. The aim of this study was to establish a molecular design strategy for a novel hypoxia-targeting therapy for intestinal T-cell lymphoma (ITL) in dogs. We assessed the relationship between immunohistochemistry-based HIF-1α expression and clinical information, including signalment, tumour area, clinical signs, systemic diseases, treatment protocol, follow-up information, chemotherapy response and overall survivals (OS), using 48 tissue samples from dogs with ITL. We investigated the effects of hypoxic stimulation on the biological behaviour of cell lines from three different types of canine ITL. We assessed the effects of evofosfamide (Evo; hypoxia-activated prodrug) on cell lines cultured under hypoxic conditions. Our data showed that treatment response and overall survival might be significantly decreased in dogs with higher HIF-1α expression than in those with lower HIF-1α expression. Hypoxic culture (1% O₂ , 72 h) enhanced the invasiveness of cell lines and decreased their sensitivity to CCNU, resulting in hypoxia-dependent aggressive behaviour. Sensitivity to Evo significantly increased in cell lines cultured under hypoxia compared with those cultured under normoxia, which exhibited hypoxia-dependent apoptosis. Additionally, Evo downregulated HIF-1α expression in cell lines cultured under hypoxia, suggesting that Evo might inhibit cell growth by inactivating HIF-1α-dependent cell signalling. Our results revealed the preclinical antitumor activity of Evo and provide a rationale for treatment strategies for dogs with ITL.