Integrating poly(ADP-ribose) polymerase (PARP) inhibitors in the treatment of early breast cancer

Poly (ADP-ribose) polymerase (PARP) inhibition in cancer: Potential impact in cancer stem cells and therapeutic implications

Inhibitors of poly(ADP-ribose) polymerase (PARP) are used in mono- or combination therapies for several malignancies. They are also used as maintenance therapy for some cancers after initial treatment. While the focus of this therapeutic approach is on the effect of PARP inhibition on the bulk tumour cells, in this review, we discuss their effect on the cancer stem cells. We identify key mediators and pathways in cancer stem cells whose response to PARP inhibition is not necessarily the same as the rest of the tumour cells. Since the cancer stem cells are known drivers of growth of tumours and their resistance to therapy, the clinical outcome might be drastically different than what is expected, if the effect of PARP inhibition on the cancer stem cells is not taken into account.

Reproductive issues in carriers of germline pathogenic variants in the BRCA1/2 genes: an expert meeting

BACKGROUND

Healthy individuals and patients with cancer who are carriers of germline pathogenic variants in the BRCA1/2 genes face multiple reproductive challenges that require appropriate counseling and specific expertise.

MAIN BODY

On December 5th-7th, 2019, patient advocates and physicians with expertise in the field of reproductive medicine, fertility preservation, and oncology were invited to "San Giuseppe Moscati" Hospital in Avellino (Italy) for a workshop on reproductive management of women with germline pathogenic variants in the BRCA1/2 genes. From the discussion regarding the current evidence and future prospective in the field, eight main research questions were formulated and eight recommendations were developed regarding fertility, fertility preservation, preimplantation genetic testing, and pregnancy in healthy carriers and patients with cancer.

CONCLUSION

Several misconceptions about the topic persist among health care providers and patients often resulting in a discontinuous and suboptimal management. With the aim to offer patient-tailored counseling about reproductive issues, both awareness of current evidences and research should be promoted.

Advances in Therapeutic Approaches for Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC), defined as breast cancer lacking expression of estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 (HER2), accounts for up to 20% of all breast cancer, and it occurs at a higher frequency in younger, African American, and Hispanic women. Compared to breast cancers that are hormone receptor and/or HER2 positive, TNBC has an aggressive clinical course and worse prognosis. Because TNBC is by definition unresponsive to endocrine therapy (eg, tamoxifen, aromatase inhibitors) and HER2-directed therapies (eg, trastuzumab), chemotherapy continues to play an important role. TNBC constitutes a molecularly heterogeneous group of tumors that can vary in response to treatment, and clinical management can be challenging, particularly for the practicing community oncologist, for whom breast cancer may be only one of many tumor types encountered. In January 2020, the Breast Cancer Therapy Expert Group (BCTEG) convened a roundtable discussion on the topic of advances in the treatment of TNBC. Topics discussed included histopathologic classification/definition of TNBC, neoadjuvant strategies, adjuvant chemotherapy (with special emphasis on management of patients who do not experience a pathologic complete response), and treatment of metastatic disease. Also reviewed was the wide range of emerging pathways and therapies currently under investigation to expand TNBC treatment options, including immunotherapies and poly(ADP-ribose) polymerase (PARP) inhibitors. This article summarizes the BCTEG discussion and highlights the key opinions relating to the treatment of patients with TNBC.

Burning Questions in the Oncofertility Counseling of Young Breast Cancer Patients

The improved prognosis of breast cancer patients makes survivorship issues an area of crucial importance. In this regard, an increased attention is needed toward the development of potential anticancer treatment-related long-term side-effects, including gonadal failure and infertility in young women. Therefore, fertility preservation and family planning are crucial issues to be addressed in all young women of reproductive age with newly diagnosed cancer. Despite a growing availability of data on the efficacy and safety of fertility preservation options and the fact that conceiving after prior history of breast cancer has become more accepted over time, there are still several gray zones in this field so that many physicians remain uncomfortable to deal with these topics. The purpose of this review is to answer some of the most controversial questions frequently asked by patients during their oncofertility counseling, in order to provide a detailed and up-to-date overview on the evidence available in this field to physicians involved in the care of young women with breast cancer.

Phase I dose-escalation and expansion study of PARP inhibitor, fluzoparib (SHR3162), in patients with advanced solid tumors

Objective

Fluzoparib (SHR3162) is a novel, potent poly(ADP-ribose) polymerases (PARP)1, 2 inhibitor that showed anti-tumor activity in xenograft models. We conducted a phase I, first-in-human, dose-escalation and expansion (D-Esc and D-Ex) trial in patients with advanced solid cancer.

Methods

This was a 3+3 phase I D-Esc trial with a 3-level D-Ex at 5 hospitals in China. Eligible patients for D-Esc had advanced solid tumors refractory to standard therapies, and D-Ex enrolled patients with ovarian cancer (OC). Fluzoparib was administered orally once or twice daily (bid) at 11 dose levels from 10 to 400 mg/d. Endpoints included dose-finding, safety, pharmacokinetics, and antitumor activity.

Results

Seventy-nine patients were enrolled from March, 2015 to January, 2018 [OC (47, 59.5%); breast cancer (BC) (16, 20.3%); colorectal cancer (8, 10.1%), other tumors (8, 10.1%)]; 48 patients were treated in the D-Esc arm and 31 in the D-Ex arm. The maximum tolerated dose (MTD) was 150 mg bid, with a half-life of 9.14 h. Grade 3/4 adverse events included anemia (7.6%) and neutropenia (5.1%). The objective response rate (ORR) was 30% (3/10) in patients with platinum-sensitive OC and 7.7% (1/13) in patients with BC. Among patients treated with fluzoparib ≥120 mg/d, median progression-free survival (mPFS) was 7.2 [95% confidence interval (95% CI), 1.8−9.3] months in OC, 9.3 (95% CI, 7.2−9.3) months in platinum-sensitive OC, and 3.5 (range, 2.0−28.0) months in BC. In patients with germline BC susceptibility gene mutation (gBRCA^Mut) (11/43 OC; 2/16 BC), mPFS was 8.9 months for OC (range, 1.0−23.2; 95% CI, 1.0−16.8) and 14 and 28 months for BC (those two patients both also had somaticBRCA^Mut).

Conclusions

The MTD of fluzoparib was 150 mg bid in advanced solid malignancies. Fluzoparib demonstrated single-agent antitumor activity in BC and OC, particularly in BRCA^Mut and platinum-sensitive OC.

An update on genetic risk assessment and prevention: the role of genetic testing panels in breast cancer

Introduction: In the past 5 years, multi-gene panels have replaced the practice of BRCA1 and BRCA2 genetic testing in cases of suspected inherited breast cancer susceptibility. A variety of genes have been included on these panels without certainty of their clinical utility. Pertinent current and historical literature was reviewed to provide an up-to-date snapshot of the changing landscape of the use of gene panel tests in the context of breast cancer. Areas covered: Following a recent review of the evidence, 10 genes have been found to have definitive evidence of increased breast cancer risk with variable penetrance. Here, we review the recent changes to the practice of multi-gene panel use in breast cancer diagnoses, including an update on next generation sequencing, alternative models of genetic testing, considerations when ordering these panel tests, and recommendations for management in identified carriers for a variety of genes. A comparison of screening recommendations and carrier frequencies from recent studies is also explored. Lastly, we consider what the future of hereditary oncologic genetic testing holds. Expert opinion: The transition to multi-gene panels in breast cancer patients has improved the likelihood of capturing a rare variant in a well-established gene associated with hereditary breast cancer (e.g. BRCA1 and BRCA2, TP53). There is also an increase in the likelihood of uncovering an uncertain result. This could be in the form of a variant of uncertain significance, or a pathogenic variant in a gene with questionable breast cancer risk-association. Concurrently, a changing landscape of who orders genetic tests will improve access to genetic testing. This pervasiveness of genetic testing must be accompanied with increased genetic literacy in all health-care providers, and access to support from genetics professionals for management of patients and at-risk family members.