Somatic Mutational Profile of High-Grade Serous Ovarian Carcinoma and Triple-Negative Breast Carcinoma in Young and Elderly Patients: Similarities and Divergences

Background: Triple-negative breast cancer (TNBC) and High-Grade Serous Ovarian Cancer (HGSOC) are aggressive malignancies that share similarities; however, different ages of onset may reflect distinct tumor behaviors. Thus, our aim was to compare somatic mutations in potential driver genes in 109 TNBC and 81 HGSOC from young (Y ≤ 40 years) and elderly (E ≥ 75 years) patients. Methods: Open access mutational data (WGS or WES) were collected for TNBC and HGSOC patients. Potential driver genes were those that were present in the Cancer Gene Census—CGC, the Candidate Cancer Gene Database—CCGD, or OncoKB and those that were considered pathogenic in variant effect prediction tools. Results: Mutational signature 3 (homologous repair defects) was the only gene that was represented in all four subgroups. The median number of mutated CGCs per sample was similar in HGSOC (Y:3 vs. E:4), but it was higher in elderly TNBC than it was in young TNBC (Y:3 vs. E:6). At least 90% of the samples from TNBC and HGSOC from Y and E patients presented at least one known affected TSG. Besides TP53, which was mutated in 67–83% of the samples, the affected TSG in TP53 wild-type samples were NF1 (yHGSOC and yTNBC), PHF6 (eHGSOC and yTNBC), PTEN, PIK3R1 and ZHFX3 (yTNBC), KMT2C, ARID1B, TBX3, and ATM (eTNBC). A few samples only presented one affected oncogene (but no TSG): KRAS and TSHR in eHGSOC and RAC1 and PREX2 (a regulator of RAC1) in yTNBC. At least ⅔ of the tumors presented mutated oncogenes associated with tumor suppressor genes; the Ras and/or PIK3CA signaling pathways were altered in 15% HGSOC and 20–35% TNBC (Y vs. E); DNA repair genes were mutated in 19–33% of the HGSOC tumors but were more frequently mutated in E-TNBC (56%). However, in HGSOC, 9.5% and 3.3% of the young and elderly patients, respectively, did not present any tumors with an affected CGC nor did 4.65% and none of the young and elderly TNBC patients. Conclusion: Most HGSOC and TNBC from young and elderly patients present an affected TSG, mainly TP53, as well as mutational signature 3; however, a few tumors only present an affected oncogene or no affected cancer-causing genes.

Targeting triple-negative breast cancer: optimising therapeutic outcomes

BACKGROUND

Triple-negative breast cancer (TNBC) is a distinct subset of breast cancer (BC) defined by the lack of immunohistochemical expression of the estrogen and progesterone receptors and human epidermal growth factor receptor 2. It is highly heterogeneous and displays overlapping characteristics with both basal-like and BC susceptibility gene 1 and 2 mutant BCs. This review evaluates the activity of emerging targeted agents in TNBC.

DESIGN

A systematic review of PubMed and conference databases was carried out to identify randomised clinical trials reporting outcomes in women with TNBC treated with targeted and platinum-based therapies.

RESULTS AND DISCUSSION

Our review identified TNBC studies of agents with different mechanisms of action, including induction of synthetic lethality and inhibition of angiogenesis, growth, and survival pathways. Combining targeted agents with chemotherapy in TNBC produced only modest gains in progression-free survival, and had little impact on survival. Six TNBC subgroups have been identified and found to differentially respond to specific targeted agents. The use of biological preselection to guide therapy will improve therapeutic indices in target-bearing populations.

CONCLUSION

Ongoing clinical trials of targeted agents in unselected TNBC populations have yet to produce substantial improvements in outcomes, and advancements will depend on their development in target-selected populations.

Novel targeted therapeutics: inhibitors of MDM2, ALK and PARP

We reviewed preclinical data and clinical development of MDM2 (murine double minute 2), ALK (anaplastic lymphoma kinase) and PARP (poly [ADP-ribose] polymerase) inhibitors. MDM2 binds to p53, and promotes degradation of p53 through ubiquitin-proteasome degradation. JNJ-26854165 and RO5045337 are 2 small-molecule inhibitors of MDM2 in clinical development. ALK is a transmembrane protein and a member of the insulin receptor tyrosine kinases. EML4-ALK fusion gene is identified in approximately 3-13% of non-small cell lung cancer (NSCLC). Early-phase clinical studies with Crizotinib, an ALK inhibitor, in NSCLC harboring EML4-ALK have demonstrated promising activity with high response rate and prolonged progression-free survival. PARPs are a family of nuclear enzymes that regulates the repair of DNA single-strand breaks through the base excision repair pathway. Randomized phase II study has shown adding PARP-1 inhibitor BSI-201 to cytotoxic chemotherapy improves clinical outcome in patients with triple-negative breast cancer. Olaparib, another oral small-molecule PARP inhibitor, demonstrated encouraging single-agent activity in patients with advanced breast or ovarian cancer. There are 5 other PARP inhibitors currently under active clinical investigation.

Poly ADP-ribose polymerase inhibitors: science and current clinical development

PURPOSE OF REVIEW

Poly ADP-ribose polymerase inhibitors are a promising new area in cancer therapeutics. This review summarizes the current understanding of their mechanism of action, their state of clinical development, and possible mechanisms of resistance.

RECENT FINDINGS

Poly ADP-ribose polymerase inhibitors were predicted to cause lethality in cells with lesions in homologous recombination, as well as to be synergistic with cytotoxic chemotherapy. Recent clinical trial results have validated both of these hypotheses. In addition, studies have begun to examine possible mechanisms of resistance.

SUMMARY

Poly ADP-ribose polymerase inhibitors were developed with the idea of synthetic lethality in mind, a concept from classical genetics that may be a general approach to finding new targets for cancer therapy. They show activity as monotherapy in cancers with defective homologous recombination, and they may potentiate the action of conventional cytotoxic chemotherapy.

Survival in epithelial ovarian cancer: a multivariate analysis incorporating BRCA mutation status and platinum sensitivity

BACKGROUND

Patients with BRCA-associated ovarian cancer (OC) have a survival advantage over those with sporadic OC. To further explore this, we examined the impact of prognostic factors on disease-free survival (DFS) and overall survival (OS) in patients with known BRCA mutation status.

PATIENTS AND METHODS

We reviewed stage III-IV OC patients treated at our institution between 1 December 1996 and 30 September 2006 and also tested on protocol for BRCA mutations. Impact on DFS and OS was determined by Kaplan-Meier analysis and a Cox proportional hazards model.

RESULTS

Of the 110 patients, 36 had deleterious BRCA mutations [BRCA (+)] and 74 were BRCA wild type [BRCA(-)]. Thirty-one of 36 (86%) BRCA (+) and 60 of 74 (81%) BRCA (-) patients were platinum sensitive (P = 0.60). Median OS was longer for BRCA (+) patients (not reached versus 67.8 months; P = 0.02), but DFS was similar (26.9 versus 24.0, P = 0.3). On multivariate analysis, OS correlated with primary platinum sensitivity [HR = 0.15; 95% CI (confidence interval) 0.06-0.34] and BRCA (+) mutation status (HR = 0.33; 95% CI 0.12-0.86).

CONCLUSIONS

BRCA mutation status predicted OS independent of primary platinum sensitivity, suggesting that underlying tumor biology contributes to disease outcome and may be worthy of consideration in future clinical trial design.

A review of triple-negative breast cancer

BACKGROUND

An estimated 1 million cases of breast cancer are diagnosed annually worldwide. Of these, more than 170,000 are described as triple-negative. Triple-negative breast cancer (TNBC) is defined by the lack of protein expression of estrogen receptor (ER) and progesterone receptor (PR) and the absence of HER2 protein overexpression. TNBC is a subtype of breast cancer that overlaps with the "basal-like" breast cancer. TNBC has significant clinical implications.

METHODS

The epidemiology, diagnosis, clinical course, prognosis, and pathology of this subtype of breast cancer are reviewed. The authors compare the "triple-negative" and "basal-like" definitions of breast cancer. A discussion of both standard and experimental treatments for TNBC is included.

RESULTS

The poor prognosis of high-grade TNBC relates to poor disease-free interval in the adjuvant setting, shortened progression-free survival in the metastatic setting, and the lack of targeted therapy. However, not all TNBCs are associated with a poor prognosis.

CONCLUSIONS

Although chemotherapy is the main current treatment of this subtype of breast cancer, new agents such as PARP inhibitors, which show promise in the treatment of TNBC, are currently in clinical trials.

Indicators of homologous recombination deficiency in breast cancer and association with response to neoadjuvant chemotherapy

BACKGROUND

Tumors with homologous recombination deficiency (HRD), such as BRCA1-associated breast cancers, are not able to reliably repair DNA double-strand breaks (DSBs) and are therefore highly sensitive to both DSB-inducing chemotherapy and poly (ADP-ribose) polymerase inhibitors. We have studied markers that may indicate the presence of HRD in HER2-negative breast cancers and related them to neoadjuvant chemotherapy response.

PATIENTS AND METHODS

Array comparative genomic hybridization (aCGH), BRCA1 promoter methylation, BRCA1 messenger RNA (mRNA) expression and EMSY amplification were assessed in 163 HER2-negative pretreatment biopsies from patients scheduled for neoadjuvant chemotherapy.

RESULTS

Features of BRCA1 dysfunction were frequent in triple-negative (TN) tumors: a BRCA1-like aCGH pattern, promoter methylation and reduced mRNA expression were observed in, respectively, 57%, 25% and 36% of the TN tumors. In ER+ tumors, a BRCA2-like aCGH pattern and the amplification of the BRCA2 inhibiting gene EMSY were frequently observed (43% and 13%, respectively) and this BRCA2-like profile was associated with a better response to neoadjuvant chemotherapy.

CONCLUSIONS

Abnormalities associated with BRCA1 inactivation are present in about half of the TN breast cancers but were not predictive of chemotherapy response. In ER+/HER2- tumors, a BRCA2-like aCGH pattern was predictive of chemotherapy response. These findings should be confirmed in independent series.

A review of PARP inhibitors: from bench to bedside

BACKGROUND

Poly(adenosine diphosphate [ADP]-ribose) polymerase (PARP) inhibitors, with novel and selective mechanisms of action, have moved from the laboratory to the clinic in just the last few years.

DESIGN

We conducted an extensive review of PARP inhibitors using a Medline search. We also searched abstracts in databases of major international oncology meetings from the last 4 years.

RESULTS

To understand the mechanisms of action of PARP inhibitors requires a basic understanding of DNA repair mechanisms and the critical role of the PARP enzyme. We briefly review these DNA repair mechanisms, the concept of 'synthetic lethality', and how PARP inhibitors play a role to selectively disrupt DNA repair in cells with absent or dysfunctional BRCA genes. We review the preclinical data highlighting this unique and selective mechanism of action and we discuss early but highly promising clinical data and ongoing studies.

CONCLUSION

PARP inhibitors show promise as a powerful therapeutic tool, especially in the management of BRCA-associated breast and ovarian cancers but also in tumours where BRCA genes may be dysfunctional. Clinical studies are ongoing and many translational questions remain unanswered that will help clarify how to determine the best way to use PARP inhibitors.

Does Race Affect Outcomes in Triple Negative Breast Cancer?

Background

There is discordance among studies assessing the impact of race on outcome of patients with Triple Negative Breast Cancer (TNBC). We assessed survival outcomes for African American (AA) versus Caucasian (CA) women with TNBC treated at an urban cancer center in Memphis, TN with a predominant AA patient population.

Methods

Patients with Stage I-III TNBC were identified from our breast database. Event free survival (EFS) and Breast cancer specific survival (BCSS) were the primary outcome measures. Cox proportional hazards models were fitted for EFS and BCSS.

Results

Of the 124 patients, 71% were AA. No significant association between race and stage ( P = 0.21) or menopausal status ( P = 0.15) was observed. Median age at diagnosis was significantly lower for AA versus CA women (49.5 vs. 55 years, P = 0.024). 92% of the patients received standard neo/adjuvant chemotherapy, with no significant difference in duration and type of chemotherapy between the races. With a median follow up of 23 months, 28% of AA vs. 19% of CA women had an event ( P = 0.37). 3 year EFS and BCSS trended favorably towards CA race (77% vs. 64%, log rank P = 0.20 and 92% vs. 76%, P = 0.13 respectively) with a similar trend noted on multiple variable modeling (EFS: HR 0.62, P = 0.29; BCSS: HR 0.36, P = 0.18). AA women ≥50 years at diagnosis had a significantly worse BCSS than the CA women in that age group ( P = 0.012).

Conclusion

Older AA women with TNBC have a significantly worse breast cancer specific survival than their CA counterparts. Overall, there is a trend towards lower survival for AA women compared to Caucasians despite uniformity of tumor phenotype and treatment. The high early event rate, irrespective of race, underscores the need for effective therapies for women with TNBC.

HUNK suppresses metastasis of basal type breast cancers by disrupting the interaction between PP2A and cofilin-1

Metastasis leads to the death of most cancer patients, and basal breast cancer is the most aggressive breast tumor type. Metastasis involves a complex cell migration process dependent on cytoskeletal remodeling such that targeting such remodeling in tumor cells could be clinically beneficial. Here we show that Hormonally Up-regulated Neu-associated Kinase (HUNK) is dramatically down-regulated in tumor samples and cell lines derived from basal breast cancers. Reconstitution of HUNK expression in basal breast cancer cell lines blocked actin polymerization and reduced cell motility, resulting in decreased metastases in two in vivo murine cancer models. Mechanistically, HUNK overexpression sustained the constitutive phosphorylation and inactivation of cofilin-1 (CFL-1), thereby blocking the incorporation of new actin monomers into actin filaments. HUNK reconstitution in basal breast cancer cell lines prevented protein phosphatase 2-A (PP2A), a phosphatase putatively acting on CFL-1, from binding to CFL-1. Our investigation of HUNK suggests that the interaction between PP2A and CFL-1 may be a target for antimetastasis therapy, particularly for basal breast cancers.