Platinum-based neoadjuvant chemotherapy for triple-negative breast cancer: a systematic review and meta-analysis

FOXO4 suppresses cisplatin resistance of triple-negative breast cancer by inhibiting autophagy

BACKGROUND

Resistance to chemotherapy containing cisplatin (DDP) is a main challenge in the treatment of triple-negative breast cancer (TNBC). Forkhead box O4 (FOXO4) is frequently downregulated in DDP-resistant cells. However, it is unclear whether FOXO4 down-regulation is related to DDP resistance. Here, we investigated the relationship between FOXO4 and DDP resistance in TNBC.

METHODS

We established the DDP-resistant cell lines MDA-MB-231/DDP and BT-549/DDP through in vitro selection. CCK-8 and colony formation assays analyzed cell growth. The resistance index was calculated. Cell autophagy was evaluated. Western blotting and qRT-PCR measured protein and gene expression. The binding between FOXO4 and TGF-β1 was determined by the dual-luciferase reporter assay.

RESULTS

FOXO4 expression was significantly lower in MDA-MB-231/DDP and BT-549/DDP cells. FOXO4 overexpression increased the sensitivity of TNBC cells to DDP. The PI3K class Ⅲ and Beclin-1 levels and LC3-II/LC3-I ratio elevated significantly in DDP-resistant cells. Moreover, the autophagic flux was enhanced in DDP-resistant cells. 3-MA enhanced the sensitivity of TNBC cells to DDP by inhibiting autophagy. Overexpression of FOXO4, treatment with 3-MA, and their combination significantly reduced the drug resistance index. FOXO4 directly targeted TGF-β1. Additionally, TGF-β1 knockdown inhibited autophagy and restored the sensitivity of DDP-resistant cells to DDP. Mechanistically, FOXO4 affected TNBC resistance to DDP by regulating autophagy and TGF-β1.

CONCLUSION

FOXO4 overexpression, in combination with autophagy inhibitors, can significantly improve the sensitivity of TNBC-resistant cells to DDP. These findings reveal the role and mechanism of FOXO4 in DDP sensitivity and may provide evidence for the development of TNBC therapies.

STIL facilitates the development and malignant progression of triple-negative breast cancer through activation of Fanconi anemia pathway via interacting with KLF16

BACKGROUND

STIL is an important cell cycle-regulating protein specifically recruited to the mitotic centrosome to promote the replication of centrioles in dividing cells. However, the potential role of STIL in the regulation of the biological functions of triple-negative breast cancer remains still unclear.

METHODS

We screened for differentially expressed STIL in the Cancer Genome Atlas database. The expression of STIL protein in 10 pairs of breast cancer tissues and adjacent normal tissues was further assessed by western blotting. Functionally, the knockdown and overexpression of STIL have been used to explore the effects of STIL on breast cancer cell proliferation, migration, and invasion. Mechanistically, RNA-seq, dual-luciferase reporter assay, chromatin immunoprecipitation assay, mass spectrometry, immunoprecipitation assay, and DNA pull-down assay were performed.

RESULTS

Breast cancer tissues and cells have higher STIL expression than normal tissues and cells. STIL knockdown impairs breast cancer cell growth, migration, and invasion, whereas STIL overexpression accelerates these processes. STIL promotes breast cancer progression by regulating FANCD2 expression, and exploration of its molecular mechanism demonstrated that STIL interacts with KLF16 to regulate the expression of FANCD2.

CONCLUSIONS

Collectively, our findings identified STIL as a critical promoter of breast cancer progression that interacts with KLF16 to regulate Fanconi anemia pathway protein FANCD2. In summary, STIL is a potential novel biomarker and therapeutic target for breast cancer.

Comparison of the efficacy of taxanes with carboplatin and anthracyclines with taxanes in neoadjuvant chemotherapy for stage II-III triple negative breast cancer: a retrospective analysis

PURPOSE

The neoadjuvant chemotherapy (NACT) regimen for triple negative breast cancer (TNBC) primarily consists of anthracyclines and taxanes, and the addition of platinum-based drugs can further enhance the efficacy. However, it is also accompanied by more adverse events, and considering the potential severe and irreversible toxicity of anthracyclines, an increasing number of studies are exploring nonanthracycline regimens that combine taxanes and platinum-based drugs.

METHODS

The retrospective study included 273 stage II-III TNBC patients who received NACT. The AT group, consisting of 195 (71.4%) patients, received a combination of anthracyclines and taxanes, while the TCb group, consisting of 78 (28.6%) patients, received a combination of taxanes and carboplatin. Logistic regression analysis was performed to evaluate the factors influencing pathological complete response (pCR) and residual cancer burden (RCB). The log-rank test was used to assess the differences in event-free survival (EFS) and overall survival (OS) among the different treatment groups. Cox regression analysis was conducted to evaluate the factors influencing EFS and OS.

RESULTS

After NACT and surgery, the TCb group had a higher rate of pCR at 44.9%, as compared to the AT group at 31.3%. The difference between the two groups was 13.6% (OR = 0.559, 95% CI 0.326-0.959, P = 0.035). The TCb group had a 57.7% rate of RCB 0-1, which was higher than the AT group's rate of 42.6%. The difference between the two groups was 15.1% (OR = 0.543, 95% CI 0.319-0.925, P = 0.024), With a median follow-up time of 40 months, the TCb group had better EFS (log-rank, P = 0.014) and OS (log-rank, P = 0.040) as compared to the AT group. Clinical TNM stage and RCB grade were identified as independent factors influencing EFS and OS, while treatment group was identified as an independent factor influencing EFS, with a close-to-significant impact on OS.

CONCLUSION

In stage II-III triple TNBC patients, the NACT regimen combining taxanes and carboplatin yields higher rates of pCR and significant improvements in EFS and OS as compared to the regimen combining anthracyclines and taxanes.

Long-term survival after neoadjuvant therapy for triple-negative breast cancer under different treatment regimens: a systematic review and network meta-analysis

BACKGROUND

Triple-negative breast cancer (TNBC) is a life-threatening subtype of breast cancer with limited treatment options. Therefore, this network meta-analysis (NMA) aimed to evaluate and compare the effect of various neoadjuvant chemotherapy (NCT) options on the long-term survival of patients with TNBC.

METHODS

PubMed, Embase, Medline, Cochrane Library, Web of Science, and major international conference databases were systematically searched for randomized controlled trials (RCTs) on the efficacy of various NCT options in patients with TNBC. Searches were performed from January 2000 to June 2023. Study heterogeneity was assessed using the I2 statistic. Hazard ratios (HRs) and 95% confidence intervals (CIs) were used to evaluate disease-free survival (DFS) and overall survival (OS). Odds ratios (ORs) and 95% CIs were used to evaluate the pathologic complete response (pCR). The primary outcome was DFS.

RESULTS

We conducted an NMA of 21 RCTs involving 8873 patients with TNBC. Our study defined the combination of anthracyclines and taxanes as the preferred treatment option. On this basis, the addition of any of the following new drugs is considered a new treatment option: bevacizumab (B), platinum (P), poly-ADP-ribose polymerase inhibitors (PARPi), and immune checkpoint inhibitor (ICI). Based on the surface under the cumulative ranking curve (SUCRA) values, the top three SUCRA area values of DFS were taxanes, anthracycline, and cyclophosphamide (TAC; 89.23%); CT (84.53%); and B (81.06%). The top three SUCRA area values of OS were CT (83.70%), TAC (62.02%), and B-containing regimens (60.06%). The top three SUCRA area values of pCR were B + P-containing regimens (82.7%), ICI + P-containing regimens (80.2%), and ICI-containing regimens (61.8%).

CONCLUSIONS

This NMA showed that standard chemotherapy is a good choice with respect to long-term survival. Moreover, B associated with P-containing regimens is likely to be the optimal treatment option for neoadjuvant TNBC in terms of pCR.

Neoadjuvant Chemotherapy in Patients with HER2-Negative Breast Cancer: A Report from Clinical Breast Cancer Registry of Iran

BACKGROUND

Neoadjuvant chemotherapy (NCT) has become an increasingly popular approach in management of breast cancer (BC). This study was conducted to evaluate the pathologic response and 36-month recurrence and survival rates of patients with human epidermal growth factor receptor 2 (HER2)-negative BC treated with different NCT regimens.

METHODS

A total of 163 female patients with HER2-negative BC who received NCT during 2017-2020 were identified from the Clinical Breast Cancer Registry of Iran and entered the study. The prescribed NCT regimens included 4 cycles of doxorubicin plus cyclophosphamide, 4 cycles of doxorubicin plus cyclophosphamide followed by 4 cycles of paclitaxel, 4 cycles of doxorubicin plus cyclophosphamide followed by 4 cycles of docetaxel or 6 cycles of doxorubicin plus cyclophosphamide plus docetaxel (TAC).

RESULTS

Thirty-two patients (19.6%) experienced pathologic complete response (pCR). TAC regimen, triple negative-BC and ki67>10% were significantly associated with increased pCR. The recurrence, overall survival (OS) and disease-free survival (DFS) rate at 36 months for all patients were 16.6%, 84.7% and 79.8%, respectively. Type of neoadjuvant regimen as well as age, hormone receptor status, Ki67, grade, clinical stage, type of surgery and pathologic response to chemotherapy did not significantly influence the survival and recurrence; however, TAC results in improved recurrence, OS and DFS rates.

CONCLUSION

This study provides further evidence that NCT is a viable treatment option for patients with HER2-negative BC. The TAC regimen resulted in a significantly higher pCR rate compared to other regimens, but did not result in a significant improvement in recurrence, OS and DFS and rates.

TRPML1 as a potential therapeutic target for triple-negative breast cancer: a review

Triple-negative breast cancer (TNBC) is the most refractory subtype of breast cancer, and effective treatments are urgently needed owing to its poor prognosis. Surgery, radiotherapy, and chemotherapy, alone or in combination, are the leading choices for TNBC therapy. Although promising approaches and procedures have emerged, several challenges, such as off-target effects, drug resistance, and severe side effects, remain to be addressed. Recently, transient receptor potential channel mucolipin 1 (TRPML1) has attracted the attention of researchers because its expression has been implicated in numerous diseases, including cancer. TRPML1 regulates biological events and signaling pathways, including autophagic flux, exocytosis, ionic homeostasis, and lysosomal biogenesis, all contributing to tumorigenesis and cancer progression. TRPML1 also functions as a building block for cancer cell growth, mitogenic signaling, priming tissues for metastasis, and activation of transcriptional programs, processes involved in several malignant tumors. This review provides an overview of breast cancer epidemiology and diagnostic techniques and then discusses the existing therapeutics. Additionally, we elaborate on the development of, and associated challenges to, TNBC diagnostics and treatment and the feasibility of TRPML1 as a therapeutic target for TNBC.

A meta-analysis of application of PD-1/PD-L1 inhibitor-based immunotherapy in unresectable locally advanced triple-negative breast cancer

Aims: The purpose of this study was to explore the efficacy of immunotherapy for patients with triple-negative breast cancer (TNBC). Materials & methods: Randomized clinical trials comparing immunotherapy with chemotherapy for advanced TNBC patients were included. Results: A total of six articles (3183 patients) were eligible for this meta-analysis. PD-1/PD-L1 inhibitor-based immunotherapy combined with chemotherapy can significantly increase the progression-free survival (hazard ratio [HR] = 0.82; 95% CI = 0.76-1.14; p < 0.001) of unresectable locally advanced or metastatic TNBC patients without effect on overall survival, compared with chemotherapy. Conclusion: PD-1/PD-L1 inhibitors-based immunotherapy can safely improve progression-free survival in patients with unresectable locally advanced or metastatic TNBC, but has no effect on overall survival.

Breast cancer: miRNAs monitoring chemoresistance and systemic therapy

With a high mortality rate that accounts for millions of cancer-related deaths each year, breast cancer is the second most common malignancy in women. Chemotherapy has significant potential in the prevention and spreading of breast cancer; however, drug resistance often hinders therapy in breast cancer patients. The identification and the use of novel molecular biomarkers, which can predict response to chemotherapy, might lead to tailoring breast cancer treatment. In this context, accumulating research has reported microRNAs (miRNAs) as potential biomarkers for early cancer detection, and are conducive to designing a more specific treatment plan by helping analyze drug resistance and sensitivity in breast cancer treatment. In this review, miRNAs are discussed in two alternative ways-as tumor suppressors to be used in miRNA replacement therapy to reduce oncogenesis and as oncomirs to lessen the translation of the target miRNA. Different miRNAs like miR-638, miR-17, miR-20b, miR-342, miR-484, miR-21, miR-24, miR-27, miR-23 and miR-200 are involved in the regulation of chemoresistance through diverse genetic targets. For instance, tumor-suppressing miRNAs like miR-342, miR-16, miR-214, and miR-128 and tumor-promoting miRNAs like miR101 and miR-106-25 cluster regulate the cell cycle, apoptosis, epithelial to mesenchymal transition and other pathways to impart breast cancer drug resistance. Hence, in this review, we have discussed the significance of miRNA biomarkers that could assist in providing novel therapeutic targets to overcome potential chemotherapy resistance to systemic therapy and further facilitate the design of tailored therapy for enhanced efficacy against breast cancer.

Pathological complete response to neoadjuvant chemotherapy in triple negative breast cancer - single hospital experience

BACKGROUND

Triple-negative breast cancer is a heterogeneous molecular subtype of BC. Pathological complete response (pCR) is an important surrogate marker for recurrence-free and overall survival.

AIM OF STUDY

The aim of this study was to evaluate clinical and pathological factors that are associated with complete pathological response status in triple-negative breast cancer patients receiving neoadjuvant chemotherapy.

MATERIALS AND METHODS

Eighty triple-negative breast cancer patients who underwent neoadjuvant chemotherapy followed by surgery at Pauls Stradins Clinical University Hospital between January 2018 and January 2020 were retrospectively analysed. Twenty-six patients (32.5%) were BRCA1/2 pathogenic variant carriers.

RESULTS

A total of 32.5% (n = 26) of patients in all study groups and 57.7% (n = 15) of patients with BRCA1/2 pathogenic variants achieved pCR. Forty-seven patients received platinum-based neoadjuvant chemotherapy, and 19 patients (40.4%) achieved complete pathological response. Patients in the pCR group presented with significantly higher Ki-67 scores (p = 0.007), BRCA1/2 pathogenic variants (p = 0.001) and younger age (p = 0.02) than those in the non-pCR group. pCR did not significantly impact recurrence-free survival (RFS) or overall survival (OS). Multivariate analysis revealed that pretreatment N stage (clinical nodal status) was an independent prognostic factor for RFS and OS.

CONCLUSIONS

BRCA1 pathogenic variants, high Ki67 score and young age were predictors of pathological complete response, while clinical nodal status predicted survival outcomes in triple-negative breast cancer.

Breast-Conserving Surgery in Triple-Negative Breast Cancer: A Retrospective Cohort Study

Objectives

The aim of the study is to evaluate the efficacy and prognosis of neoadjuvant chemotherapy (NAC) combined with breast-conserving surgery (BCS) in treating triple-negative breast cancer (TNBC) and analyze the influencing factors and predictors of the efficiency and prognosis of NAC.

Methods

A retrospective cohort study was conducted by dividing patients into two groups according to two different therapy methods. With BCS as the exposure factor, 46 cases were assigned to the exposed group and 80 cases to the nonexposed group. We compare the difference in operation-related indicators, postoperative complications, local recurrence rate, distant metastasis rate, and overall survival (OS) rate between the two groups. The factors affecting the efficiency and prognosis of NAC were analyzed by binary logistic regression, and the optimal cutoff value was determined by the area under the ROC curve (AUC). The survival curve was plotted, and the univariate log-rank test was performed to analyze the difference in OS between the two groups. The influencing factors of OS were analyzed by the Cox risk regression model.

Results

NAC + BCS resulted in significantly less intraoperative blood loss, lower incidence of postoperative complications, and shorter operative time and length of hospital stay than that in NAC (P < 0.05). There was no significant difference in local recurrence, distant metastasis, or OS between the two groups (P > 0.05). Multivariate analysis showed that the clinical stage I and Ki-67 high expression were independent protective factors of the efficacy of NAC. The high expression of Ki-67 and nondecline expression of Ki-67 were independent risk factors of prognosis. Ki-67 high expression was an independent risk factor of OS (P < 0.05). The ROC curve showed that the AUC of Ki-67 for NAC efficacy, prognosis, and OS were 0.706, 0.820, and 0.687, respectively, with optimal cutoff values of 25.5%, 29.0%, and 32.5%, respectively. Survival analysis showed that the OS of patients with NAC + BCS was 73.9% and NAC + MRM was 70.0% (P > 0.05). In the low expression subgroup of Ki-67, the OS of the two groups were 100.0% and 77.8%, respectively (P=0.060). In the high expression subgroup of Ki-67, the OS of the two groups were 53.8% and 63.6%, respectively (P=0.419).

Conclusions

NAC + BCS is a good method for treating TNBC, which has an obvious short-term effect and a good long-term prognosis. Clinical stage I and the high expression of Ki-67 are independent protective factors for the efficacy of NAC. The high expression of Ki-67 and nondecline expression of Ki-67 are independent risk factors of prognosis. Ki-67 is a potential predictor for the efficacy, prognosis, and OS of NAC in TNBC patients. The high expression of Ki-67 indicates better NAC efficacy, a poorer prognosis, and a lower OS.

Polymeric Micelles for Breast Cancer Therapy: Recent Updates, Clinical Translation and Regulatory Considerations

With the growing burden of cancer, parallel advancements in anticancer nanotechnological solutions have been witnessed. Among the different types of cancers, breast cancer accounts for approximately 25% and leads to 15% of deaths. Nanomedicine and its allied fields of material science have revolutionized the science of medicine in the 21st century. Novel treatments have paved the way for improved drug delivery systems that have better efficacy and reduced adverse effects. A variety of nanoformulations using lipids, polymers, inorganic, and peptide-based nanomedicines with various functionalities are being synthesized. Thus, elaborate knowledge of these intelligent nanomedicines for highly promising drug delivery systems is of prime importance. Polymeric micelles (PMs) are generally easy to prepare with good solubilization properties; hence, they appear to be an attractive alternative over the other nanosystems. Although an overall perspective of PM systems has been presented in recent reviews, a brief discussion has been provided on PMs for breast cancer. This review provides a discussion of the state-of-the-art PMs together with the most recent advances in this field. Furthermore, special emphasis is placed on regulatory guidelines, clinical translation potential, and future aspects of the use of PMs in breast cancer treatment. The recent developments in micelle formulations look promising, with regulatory guidelines that are now more clearly defined; hence, we anticipate early clinical translation in the near future.

Treatment for Triple-Negative Breast Cancer: An Umbrella Review of Meta-Analyses

Purpose

In recent years, many meta-analyses of triple-negative breast cancer (TNBC) treatment have been published; however, these studies still lack systematic summary. Therefore, the aim of this study is to summarize and evaluate the evidence level and efficacy of treatment for TNBC.

Materials and Methods

Retrospective and prospective studies on treatment of TNBC were searched in the PubMed, Embase, and Cochrane Library databases. The literature search deadline was June 30, 2021. Two investigators independently screened the literature and extracted the data. In addition, the joint World Health Organization–United Nations Food and Agriculture Organization expert consultation was used to evaluate the validity of the evidence.

Results

A total of 28 meta-analyses were included in this study. The treatment interventions for TNBC mainly included surgery, chemotherapy (CT), radiotherapy, molecular targeted therapy, immunotherapy, zoledronic acid, and gonadotropin-releasing hormone (GnRH) analog. Platinum improves the pathological complete response (PCR) rate of patients treated with neoadjuvant chemotherapy (NACT), the objective remission rate (ORR) and overall survival (OS) in patients with metastatic triple-negative breast cancer. Capecitabine improves disease-free survival (DFS) and OS in patients treated with adjuvant CT. Bevacizumab was added to NACT to improve the PCR rate in patients. Immunotherapy improves the PCR rate in patients treated with NACT. The improvement in PCR rate in patients with high Ki67 expression treated with neoadjuvant therapy is highly suggestive. Other interventions had suggestive or weak evidence.

Conclusion

Among the strategies for treating TNBC, platinum, bevacizumab, and immunotherapy can lead to better PCR rates as part of a NACT regimen. Capecitabine as adjuvant CT and platinum in the treatment of metastatic TNBC can benefit patients’ survival. However, the effectiveness of other interventions for TNBC is not yet clear. Further research is needed in the future to obtain more reliable clinical evidence.

Evolving Evidence for the Optimization of Neoadjuvant Therapy in Triple-Negative Breast Cancer

Representing 15% to 20% of all invasive breast cancers, adjuvant systemic treatment for early-stage, high-risk triple-negative breast cancer (TNBC) is preferentially done in the neoadjuvant setting based on a chemotherapy backbone of anthracyclines and taxanes. Pathological complete response to neoadjuvant treatment constitutes the main objective, regarding its correlation with oncological outcomes. The optimal neoadjuvant regimen to achieve the highest rates of pathological complete response is still under investigation, with the increasing knowledge on the molecular pathways, genomic sequencing, and immunological profile of TNBC allowing for the development of a wide array of new therapeutic options. This review aims to summarize the current evidence and ongoing clinical trials of new therapeutic options for the neoadjuvant treatment of TNBC patients.

A Canadian national guideline on the neoadjuvant treatment of invasive breast cancer, including patient assessment, systemic therapy, and local management principles

Purpose

The neoadjuvant treatment of breast cancer (NABC) is a rapidly changing area that benefits from guidelines integrating evidence with expert consensus to help direct practice. This can optimize patient outcomes by ensuring the appropriate use of evolving neoadjuvant principles.

Methods

An expert panel formulated evidence-based practice recommendations spanning the entire neoadjuvant breast cancer treatment journey. These were sent for practice-based consensus across Canada using the modified Delphi methodology, through a secure online survey. Final recommendations were graded using the GRADE criteria for guidelines. The evidence was reviewed over the course of guideline development to ensure recommendations remained aligned with current relevant data.

Results

Response rate to the online survey was almost 30%; representation was achieved from various medical specialties from both community and academic centres in various Canadian provinces. Two rounds of consensus were required to achieve 80% or higher consensus on 59 final statements. Five additional statements were added to reflect updated evidence but not sent for consensus.

Conclusions

Key highlights of this comprehensive Canadian guideline on NABC include the use of neoadjuvant therapy for early stage triple negative and HER2 positive breast cancer, with subsequent adjuvant treatments for patients with residual disease. The use of molecular signatures, other targeted adjuvant therapies, and optimal response-based local regional management remain actively evolving areas. Many statements had evolving or limited data but still achieved high consensus, demonstrating the utility of such a guideline in helping to unify practice while further evidence evolves in this important area of breast cancer management.

Survival benefit of platinum-based regimen in early stage triple negative breast cancer: A meta-analysis of randomized controlled trials

Platinum (Pt)-based chemo-regimens have been proved effective in neoadjuvant and salvage chemotherapy of triple negative breast cancer (TNBC). However, the survival benefit of Pt-based regimens in early stage TNBC(eTNBC) treatment has remained unclear. We conducted a meta-analysis to explore its role in improving the clinical outcomes of eTNBC. We carried out a comprehensive literature search on 15 March 2021 for randomized controlled trials (RCTs) comparing ajuvant/neoadjuvant Pt-based and Pt-free chemo-regimens in eTNBC patients, according to PRISMA 2020. We extracted the survival data and utilized the STATA software to calculate the summarized hazard ratios (HRs) and 95% confidence interval (95% CI) for overall survival (OS) and disease-free survival (DFS). Seven eligible RCTs enrolling a total of 2,027 eTNBC patients were identified in this meta-analysis, with 1,007 receiving Pt-free regimens, and the other 1,020 patients receiving Pt-based regimens, respectively. Patients in Pt-based regimens arm were associated with significant improved DFS (HR = 0.70, 95% CI: 0.58–0.84), and OS (HR = 0.78, 95% CI: 0.61–1.00). The survival benefits of DFS remained consistent in both the two strategies of Pt usage, either adding Pt to standard anthracyclines&taxanes based regimens (A&T + Pt), or combination of Pt and taxanes alone (TPt). The survival benefits also remained consistent in either neoadjuvant or adjuvant use of Pt. The present meta-analysis of RCTs revealed that Pt-based chemo-regimens could significantly improve both DFS and OS for eTNBC patients. Based on efficiency and toxicity, we recommend Pt-based regimens for eTNBC, especially the “A&T + Pt” mode if the toxicities are tolerable, which may lead TNBC therapy into a new era.

Establishment of a New Cell Line of Canine Mammary Tumor CMT-1026

Canine mammary tumors (CMTs) have histopathological, epidemiologic and clinical characteristics similar to those in humans and are known to be one of the best models for human breast cancer (HBC). This research aimed to describe a newly established canine cell line, CMT-1026. Tumor samples were collected from a female dog exhibiting clinical mammary neoplasm, and the adherent cells were cultured. Both the histology and immunohistochemistry (IHC) of tumor samples were estimated. Cell growth, ultrastructural, cytological and immunocytochemistry (ICC) features of CMT-1026 were examined. CMT-1026 cells were inoculated into 10 female BALB/c nude mice to evaluate oncogenicity and metastatic ability. Hematoxylin-eosin (H.E.) staining of the tumors revealed an epithelial morphology. Electron microscopy was used to detect histological and cytological of smears, and ultrathin sections showed that CMT-1026 cells were polygonal and characterized by atypia and high mitotic index in the tumor, with prominent nucleoli and multinucleated cells. IHC characterization of CMT-1026 indicated ER-, PR-, HER-2, p63+, CK5/6+, and α-SMA+ epithelial cells. ICC characterization of CMT-1026 showed high expression of Claudin-1, Delta-catenin, SOX-2, and KI-67. At 2 weeks after inoculation of the CMT-1026 cells, phyma was found in 100% of the mice. The xenograft cancers showed conservation of the original H.E. features of the female dog cancer. In conclusion, CMT-1026 may be a model of canine mammary cancer that can be used in research on the pathogenesis of both CMT and HBC.