BRCAness digitalMLPA profiling predicts benefit of intensified platinum-based chemotherapy in triple-negative and luminal-type breast cancer

Long-term outcomes of young, node-negative, chemotherapy-naïve, triple-negative breast cancer patients according to BRCA1 status

BACKGROUND

Due to the abundant usage of chemotherapy in young triple-negative breast cancer (TNBC) patients, the unbiased prognostic value of BRCA1-related biomarkers in this population remains unclear. In addition, whether BRCA1-related biomarkers modify the well-established prognostic value of stromal tumor-infiltrating lymphocytes (sTILs) is unknown. This study aimed to compare the outcomes of young, node-negative, chemotherapy-naïve TNBC patients according to BRCA1 status, taking sTILs into account.

METHODS

We included 485 Dutch women diagnosed with node-negative TNBC under age 40 between 1989 and 2000. During this period, these women were considered low-risk and did not receive chemotherapy. BRCA1 status, including pathogenic germline BRCA1 mutation (gBRCA1m), somatic BRCA1 mutation (sBRCA1m), and tumor BRCA1 promoter methylation (BRCA1-PM), was assessed using DNA from formalin-fixed paraffin-embedded tissue. sTILs were assessed according to the international guideline. Patients' outcomes were compared using Cox regression and competing risk models.

RESULTS

Among the 399 patients with BRCA1 status, 26.3% had a gBRCA1m, 5.3% had a sBRCA1m, 36.6% had tumor BRCA1-PM, and 31.8% had BRCA1-non-altered tumors. Compared to BRCA1-non-alteration, gBRCA1m was associated with worse overall survival (OS) from the fourth year after diagnosis (adjusted HR, 2.11; 95% CI, 1.18-3.75), and this association attenuated after adjustment for second primary tumors. Every 10% sTIL increment was associated with 16% higher OS (adjusted HR, 0.84; 95% CI, 0.78-0.90) in gBRCA1m, sBRCA1m, or BRCA1-non-altered patients and 31% higher OS in tumor BRCA1-PM patients. Among the 66 patients with tumor BRCA1-PM and ≥ 50% sTILs, we observed excellent 15-year OS (97.0%; 95% CI, 92.9-100%). Conversely, among the 61 patients with gBRCA1m and < 50% sTILs, we observed poor 15-year OS (50.8%; 95% CI, 39.7-65.0%). Furthermore, gBRCA1m was associated with higher (adjusted subdistribution HR, 4.04; 95% CI, 2.29-7.13) and tumor BRCA1-PM with lower (adjusted subdistribution HR, 0.42; 95% CI, 0.19-0.95) incidence of second primary tumors, compared to BRCA1-non-alteration.

CONCLUSIONS

Although both gBRCA1m and tumor BRCA1-PM alter BRCA1 gene transcription, they are associated with different outcomes in young, node-negative, chemotherapy-naïve TNBC patients. By combining sTILs and BRCA1 status for risk classification, we were able to identify potential subgroups in this population to intensify and optimize adjuvant treatment.

Rates of Variants of Uncertain Significance Among Patients With Breast Cancer Undergoing Genetic Testing: Regional Perspectives

Purpose

Contrary to BRCA pathogenic variants, recommendations for management of variants of uncertain significance (VUS) are not clear and focus more on the patient’s family and personal history of cancer. Local and regional data on VUS are scarce. In this paper, we study patterns and frequency of VUS among breast cancer patients undergoing genetic testing.

Patients and Methods

Patients with breast cancer at high risk for pathogenic variants, as per the National Comprehensive Cancer Network (NCCN) guidelines, were tested at reference laboratories. Related surgical interventions were reviewed.

Results

Among a group of 1,197 patients with breast cancer who underwent genetic testing and counseling, 110 (9.2%) had VUS; most (n = 79, 71.8%) were in BRCA2. Median age (range) was 39 (25–66) years with 65 (59.1%) patients who were 40 years or younger at diagnosis. Among 103 patients with non-metastatic disease, 48 (46.6%) had breast-conserving surgery (BCS) while only 5 (4.9%) had bilateral mastectomies; all were due to bilateral disease and not prophylactic. VUS diagnosis was known prior to initial surgery in 34 (33.0%) patients; 11 (32.4%) of them had BCS only. Over the study period, only one VUS variant was upgraded to “likely positive.” The recent introduction of multiple-gene panel testing had resulted in a surge in VUS rate (22.2%) in genes other than BRCA1 or BRCA2, like PALB2, CHEK2, and ATM.

Conclusions

Rates of VUS are relatively high and increasing, mostly in non-BRCA1 or BRCA2, and this had no impact on the therapeutic or prophylactic surgical decisions. Adherence to guidelines is extremely important to avoid unnecessary procedures.

PARP Inhibitors: A Major Therapeutic Option in Endocrine-Receptor Positive Breast Cancers

Recently, OlympiAD and EMBRACA trials demonstrated the favorable efficacy/toxicity ratio of PARPi, compared to chemotherapy, in patients with HER2-negative metastatic breast cancers (mBC) carrying a germline BRCA mutation. PARPi have been largely adopted in triple-negative metastatic breast cancer, but their place has been less clearly defined in endocrine-receptor positive, HER2 negative (ER+/ HER2-) mBC. The present narrative review aims at addressing this question by identifying the patients that are more likely benefit from PARPi. Frequencies of BRCA pathogenic variant (PV) carriers among ER+/HER2- breast cancer patients have been underestimated, and many experts assume than 50% of all BRCA1/2 mutated breast cancers are of ER+/HER2- subtype. Patients with ER+/HER2- BRCA-mutated mBC seemed to have a higher risk of early disease progression while on CDK4/6 inhibitors and PARPi are effective especially when prescribed before exposure to chemotherapy. The OLYMPIA trial also highlighted the utility of PARPi in patients with early breast cancers at high risk of relapse and carrying PV of BRCA. PARPi might also be effective in patients with HRD diseases, representing up to 20% of ER+/HER2- breast cancers. Consequently, the future implementation of early genotyping strategies for identifying the patients with high-risk ER+/HER2- HRD breast cancers likely to benefit from PARPi is of high importance.

Predictive and prognostic significance of BRCAness in HER2-negative breast cancer

BACKGROUND

BRCAness is characterized as the phenotypes shared between some sporadic tumors and BRCA1/2 mutation cancers resulting in defective homologous recombination. The predictive or prognostic value of BRCAness in HER2-negative breast cancer patients who have received neoadjuvant chemotherapy (NAC) is not fully elucidated.

METHODS

We retrospectively selected 101 high-risk HER2-negative patients diagnosed with stage I-III breast cancer who underwent NAC treatment and evaluated BRCA1-like phenotype using multiplex ligation-dependent probe amplification assay. In an analysis of BRCAness, 95 out of 101 patients were analyzed.

RESULTS

In total, 70 (74%) patients had sporadic-type tumors and 25 (26%) had BRCA1-like tumors according to pre-treatment samples. The BRCA1-like phenotype was not associated with pathological complete response (pCR) rate in the entire cohort. In survival analysis, pre-treatment BRCA1-like phenotype was not associated with survival. On the other hand, post-treatment BRCA1-like patients apparently showed shorter relapse-free survival (log-rank P = 0.016) and breast cancer-specific survival (P < 0.001) compared with sporadic features. In multivariate analysis, only the post-treatment BRCA1-phenotype was significant prognostic factors (HR 5.67, 95% CI 1.19-29.3). Furthermore, we found phenotype change between BRCA1-like and sporadic type through NAC in 19% of non-pCR patients. Post-treatment Ki67 significantly decreased in the persistent sporadic tumors during treatment or sporadic tumors changed after NAC (P < 0.0001, P = 0.0078, respectively).

CONCLUSIONS

BRCAness may be useful biomarkers to predict prognosis for HER2-negative breast cancer refractory to standard chemotherapy. Our results pave the way for identifying patients who require alternative therapies.

RAD51 as a functional biomarker for homologous recombination deficiency in cancer: a promising addition to the HRD toolbox?

INTRODUCTION

Carcinomas with defects in the homologous recombination (HR) pathway are sensitive to PARP inhibitors (PARPi). A robust method to identify HR-deficient (HRD) carcinomas is therefore of utmost clinical importance. Currently available DNA-based HRD tests either scan HR-related genes such as BRCA1 and BRCA2 for the presence of pathogenic variants or identify HRD-related genomic scars or mutational signatures by using whole-exome or whole-genome sequencing data. As an alternative to DNA-based tests, functional HRD tests have been developed that assess the actual ability of tumors to accumulate RAD51 protein at DNA double strand breaks as a proxy for HR proficiency.

AREAS COVERED

This review presents an overview of currently available HRD tests and discuss the pros and cons of the different methodologies including their sensitivity for the identification of HRD tumors, their concordance with other HRD tests, and their capacity to predict therapy response.

EXPERT OPINION

With the increasing use of PARP inhibitors in the treatment of several cancers there is an urgent need to implement HRD testing in routine clinical practice. To this end, calibration of HRD thresholds and clinical validation of both DNA-based and RAD51-based HRD tests should have top-priority in the coming years.

The rediscovery of platinum-based cancer therapy

Platinum (Pt) compounds entered the clinic as anticancer agents when cisplatin was approved in 1978. More than 40 years later, even in the era of precision medicine and immunotherapy, Pt drugs remain among the most widely used anticancer drugs. As Pt drugs mainly target DNA, it is not surprising that recent insights into alterations of DNA repair mechanisms provide a useful explanation for their success. Many cancers have defective DNA repair, a feature that also sheds new light on the mechanisms of secondary drug resistance, such as the restoration of DNA repair pathways. In addition, genome-wide functional screening approaches have revealed interesting insights into Pt drug uptake. About half of cisplatin and carboplatin but not oxaliplatin may enter cells through the widely expressed volume-regulated anion channel (VRAC). The analysis of this heteromeric channel in tumour biopsies may therefore be a useful biomarker to stratify patients for initial Pt treatments. Moreover, Pt-based approaches may be improved in the future by the optimization of combinations with immunotherapy, management of side effects and use of nanodelivery devices. Hence, Pt drugs may still be part of the standard of care for several cancers in the coming years.