Metaplastic breast cancers (MBCs) are characterized by complex genomes, which seem to vary according to their histologic subtype. TERT promoter hotspot mutations and gene amplification are rare in common forms of breast cancer, but present in a subset of phyllodes tumors. Here, we sought to determine the frequency of genetic alterations affecting TERT in a cohort of 60 MBCs with distinct predominant metaplastic components (squamous, 23%; spindle, 27%; osseous, 8%; chondroid, 42%), and to compare the repertoire of genetic alterations of MBCs according to the presence of TERT promoter hotspot mutations or gene amplification. Forty-four MBCs were subjected to: whole-exome sequencing (WES; n = 27) or targeted sequencing of 341-468 cancer-related genes (n = 17); 16 MBCs were subjected to Sanger sequencing of the TERT promoter, TP53 and selected exons of PIK3CA, HRAS, and BRAF. TERT promoter hotspot mutations (n = 9) and TERT gene amplification (n = 1) were found in 10 of the 60 MBCs analyzed, respectively. These TERT alterations were less frequently found in MBCs with predominant chondroid differentiation than in other MBC subtypes (p = 0.01, Fisher’s exact test) and were mutually exclusive with TP53 mutations (p < 0.001, CoMEt). In addition, a comparative analysis of the MBCs subjected to WES or targeted cancer gene sequencing (n = 44) revealed that MBCs harboring TERT promoter hotspot mutations or gene amplification (n = 6) more frequently harbored PIK3CA than TERT wild-type MBCs (n = 38; p = 0.001; Fisher’s exact test). In conclusion, TERT somatic genetic alterations are found in a subset of TP53 wild-type MBCs with squamous/spindle differentiation, highlighting the genetic diversity of these cancers.

Purpose: Lynch syndrome is defined by germline pathogenic mutations involving DNA mismatch repair (MMR) genes and linked with the development of MMR-deficient colon and endometrial cancers. Whether breast cancers developing in the context of Lynch syndrome are causally related to MMR deficiency (MMRd), remains controversial. Thus, we explored the morphologic and genomic characteristics of breast cancers occurring in Lynch syndrome individuals. Experimental Design: A retrospective analysis of 20,110 patients with cancer who underwent multigene panel genetic testing was performed to identify individuals with a likely pathogenic/pathogenic germline variant in MLH1, MSH2, MSH6, or PMS2 who developed breast cancers. The histologic characteristics and IHC assessment of breast cancers for MMR proteins and programmed death-ligand 1 (PD-L1) expression were assessed on cases with available materials. DNA samples from paired tumors and blood were sequenced with Memorial Sloan Kettering–Integrated Mutation Profiling of Actionable Cancer Targets (≥468 key cancer genes). Microsatellite instability (MSI) status was assessed utilizing MSISensor. Mutational signatures were defined using SigMA. Results: A total of 272 individuals with Lynch syndrome were identified, 13 (5%) of whom had primary breast cancers. The majority of breast cancers (92%) were hormone receptor–positive tumors. Five (42%) of 12 breast cancers displayed loss of MMR proteins by IHC. Four (36%) of 11 breast cancers subjected to tumor-normal sequencing showed dominant MSI mutational signatures, high tumor mutational burden, and indeterminate (27%) or high MSISensor scores (9%). One patient with metastatic MMRd breast cancer received anti-PD1 therapy and achieved a robust and durable response. Conclusions: A subset of breast cancers developing in individuals with Lynch syndrome are etiologically linked to MMRd and may benefit from anti-PD1/PD-L1 immunotherapy.

To evaluate the incidence of cMET proto-oncogene aberration in a cohort of triple negative breast cancers using immunohistochemistry and fluorescence in situ hybridization (FISH) methods and correlated with patient outcome. One hundred and six female patients with diagnosis of triple negative invasive breast carcinoma at The University of Texas-M D Anderson Cancer Center from 1983 to 2009 were included in the study. Expression of cMET was assessed by IHC using rabbit monoclonal anti-total cMET antibody (SP44 from Ventana). Staining intensity was scored on a scale of 0, 1+, 2+ and 3+. cMET overexpression was defined as at least moderate membranous/cytoplasmic staining in ≥50% of tumor cells (score ≥ 2+). FISH analysis was performed using MET (7q31) specific probe (BAC clone RP11-95i20, Abbott Molecular Inc.) and the centromere probe (CEP7/D7Z1, Abbott Molecular Inc.) as internal control. cMET amplification was defined as gene copy numbers ≥4 per cell or cMET/CEP7 ratio ≥ 2. cMET status was tested for correlation using Fisher's exact test with other clinicopathological parameters. The Kaplan-Meier product limit method was used to estimate the survival outcomes. Cox proportional hazards models were fit to determine the association of cMET status by IHC, or by FISH, or by copy number with survival outcomes after adjustment for other patient and disease characteristics. Medium follow up is 69.4 months (range 9-317 months). cMET was successfully evaluated by both IHC and FISH methods in ninety-six patients. There were 13 patients whose tumors overexpressed cMET was by IHC. Two patients had cMET amplification by FISH using definitive of cMET/CEP7 ratio of ≥2 and four patients had cMET copy number >4. Only one patient showed cMET/CEP7 ratio of 2.53 and one was positive for cMET overexpression by IHC. No significant association between cMET overexpression by IHC and by FISH using cut-off of with either cMET/CEP7 ratio of ≥2 or cMET copy number of >4 (P = 1.0). There was no significant correlation between the cMET overexpression and other clinicopathological characteristics, such as patient demographics, tumor grade, stage, or chemotherapy treatment history. cMET overexpression and gene amplification did not correlate with the prognosis of TNBC regarding OS or DFS. MET amplification is a rare incidence in TNBCs. cMET overexpression is infrequent in TNBCs and may not be driven by gene amplification. Neither have significant prognostic value nor do they correlate with other clinicopathological characteristics in this TNBC cohort.

Novel proteasome inhibitor delanzomib sensitizes cervical cancer cells to doxorubicin-induced apoptosis via stabilizing tumor suppressor proteins in the p53 pathway Novel proteasome inhibitor delanzomib sensitizes cervical cancer cells to doxorubicin-induced apoptosis via stabilizing tumor suppressor proteins in the p53 pathway

Background: Delanzomib, a novel proteasome inhibitor, has demonstrated promising efficacy and antitumor ability in human multiple myeloma cell lines and patient‐derived cells. However, the potential therapeutic effects of delanzomib on breast cancer remain unknown. In this study, we show that delanzomib has antitumor effects and synergizes with doxorubicin (Dox) in human breast cancer cell lines. Methods: Cell proliferation assay and flow cytometry were used to evaluate cell viability and apoptosis in eight human breast cancer cell lines after treatment with delanzomib or Dox. Essential molecules of the p53, MAPK, and apoptosis signaling pathways were analyzed by Western blotting. Results: Delanzomib induced cell death and demonstrated synergism with Dox in all tested breast cancer cell lines. In addition, delanzomib enhanced the Dox‐induced phosphorylation of p38/JNK and the expression of transcriptional target proteins of p53, such as p21, p27, NOXA, and PUMA. Conclusion: The combined regimen of the proteasome inhibitor delanzomib with Dox chemotherapy may become an effective strategy for breast cancer therapy.