Phase I Study of Veliparib (ABT-888) Combined with Cisplatin and Vinorelbine in Advanced Triple-Negative Breast Cancer and/or BRCA Mutation-Associated Breast Cancer

PARP inhibitors in breast cancer: Bringing synthetic lethality to the bedside

Individuals with breast and ovarian cancer susceptibility gene 1 (BRCA1) or BRCA2 germline mutations have a significantly increased lifetime risk for breast and ovarian cancers. BRCA-mutant cancer cells have abnormal homologous recombination (HR) repair of DNA. In these tumors, the base excision repair (BER) pathway is important for cell survival. The poly(adenosine diphosphate-ribose) polymerase (PARP) enzymes play a key role in BER, and PARP inhibitors are effective in causing cell death in BRCA-mutant cells while sparing normal cells-a concept called synthetic lethality. PARP inhibitors are the first cancer therapeutics designed to exploit synthetic lethality. Recent clinical trials in BRCA-mutant, metastatic breast cancer demonstrated improved outcomes with single-agent PARP inhibitors (olaparib and talazoparib) over chemotherapy. However, resistance to PARP inhibitors remains a challenge. Primarily due to myelosuppression, the combination of PARP inhibitors with chemotherapy has been difficult. Novel combinations with chemotherapy, immunotherapy, and other targeted therapies are being pursued. In this review, the authors discuss current knowledge of PARP inhibitors in BRCA-mutant breast cancer and potential future directions for these agents. Cancer 2018;124:2498-506. © 2018 American Cancer Society.

Synthetic Lethality of PARP Inhibition and Ionizing Radiation is p53-dependent

PARP inhibitors (PARPi) are potentially effective therapeutic agents capable of inducing synthetic lethality in tumors with deficiencies in homologous recombination (HR)-mediated DNA repair such as those carrying BRCA1 mutations. However, BRCA mutations are rare, the majority of tumors are proficient in HR repair, and thus most tumors are resistant to PARPi. Previously, we observed that ionizing radiation (IR) initiates cytoplasmic translocation of BRCA1 leading to suppression of HR-mediated DNA repair and induction of synthetic PARPi lethality in wild-type BRCA1 and HR-proficient tumor cells. The tumor suppressor p53 was identified as a key factor that regulates DNA damage-induced BRCA1 cytoplasmic sequestration following IR. However, the role of p53 in IR-induced PARPi sensitization remains unclear. This study elucidates the role of p53 in IR-induced PARPi cytotoxicity in HR-proficient cancer cells and suggests p53 status may help define a patient population that might benefit from this treatment strategy. Sensitization to PARPi following IR was determined in vitro and in vivo utilizing human breast and glioma tumor cells carrying wild-type BRCA1 and p53, and in associated cells in which p53 function was modified by knockdown or mutation. In breast and glioma cells with proficient HR repair, IR-induced BRCA1 cytoplasmic sequestration, HR repair inhibition, and subsequent PARPi sensitization in vitro and in vivo was dependent upon functional p53.Implications: Implications: p53 status determines PARP inhibitor sensitization by ionizing radiation in multiple BRCA1 and HR-proficient tumor types and may predict which patients are most likely to benefit from combination therapy. Mol Cancer Res; 16(7); 1092-102. ©2018 AACR.

A phase I trial of paclitaxel, cisplatin, and veliparib in the treatment of persistent or recurrent carcinoma of the cervix: an NRG Oncology Study (NCT#01281852)

Background

Preclinical studies demonstrate poly(ADP-ribose) polymerase (PARP) inhibition augments apoptotic response and sensitizes cervical cancer cells to the effects of cisplatin. Given the use of cisplatin and paclitaxel as first-line treatment for persistent or recurrent cervical cancer, we aimed to estimate the maximum tolerated dose (MTD) of the PARP inhibitor veliparib when added to chemotherapy.

Patients and methods

Women with persistent or recurrent cervical carcinoma not amenable to curative therapy were enrolled. Patients had to have received concurrent chemotherapy and radiation as well as possible consolidation chemotherapy; have adequate organ function. The trial utilized a standard 3 + 3 phase I dose escalation with patients receiving paclitaxel 175 mg/m2 on day 1, cisplatin 50 mg/m2 on day 2, and escalating doses of veliparib ranging from 50 to 400 mg orally two times daily on days 1-7. Cycles occurred every 21 days until progression. Dose-limiting toxicities (DLTs) were assessed at first cycle. Fanconi anemia complementation group D2 (FANCD2) foci was evaluated in tissue specimens as a biomarker of response.

Results

Thirty-four patients received treatment. DLTs (n = 1) were a grade 4 dyspnea, a grade 3 neutropenia lasting ≥3 weeks, and febrile neutropenia. At 400 mg dose level (DL), one of the six patients had a DLT, so the MTD was not reached. Across DLs, the objective response rate (RR) for 29 patients with measurable disease was 34% [95% confidence interval (CI), 20%-53%]; at 400 mg DL, the RR was 60% (n = 3/5; 95% CI, 23%-88%). Median progression-free survival was 6.2 months (95% CI, 2.9-10.1), and overall survival was 14.5 months (95% CI, 8.2-19.4). FANCD2 foci was negative or heterogeneous in 31% of patients and present in 69%. Objective RR were not associated with FANCD2 foci (P = 0.53).

Conclusions

Combining veliparib with paclitaxel and cisplatin as first-line treatment for persistent or recurrent cervical cancer patients is safe and feasible.

Clinical trial information

NCT01281852.

Improved pharmacodynamic (PD) assessment of low dose PARP inhibitor PD activity for radiotherapy and chemotherapy combination trials

BACKGROUND

PARP inhibitors are currently evaluated in combination with radiotherapy and/or chemotherapy. As sensitizers, PARP inhibitors are active at very low concentrations therefore requiring highly sensitive pharmacodynamic (PD) assays. Current clinical PD-assays partly fail to provide such sensitivities. The aim of our study was to enable sensitive PD evaluation of PARP inhibitors for clinical sensitizer development.

MATERIAL AND METHODS

PBMCs of healthy individuals and of olaparib and radiotherapy treated lung cancer patients were collected for ELISA-based PD-assays.

RESULTS

PAR-signal amplification by ex vivo irradiation enabled an extended quantification range for PARP inhibitory activities after ex vivo treatment with inhibitors. This "radiation-enhanced-PAR" (REP) assay provided accurate IC50 values thereby also revealing differences among healthy individuals. Implemented in clinical radiotherapy combination Phase I trials, the REP-assay showed sensitive detection of PARP inhibition in patients treated with olaparib and establishes strong PARP inhibitory activities at low daily doses.

CONCLUSIONS

Combination trials of radiotherapy and novel targeted agent(s) often require different and more sensitive PD assessments than in the monotherapy setting. This study shows the benefit and relevance of sensitive and adapted PD-assays for such combination purposes and provides proof of clinically relevant cellular PARP inhibitory activities at low daily olaparib doses.

Practical Approach to Triple-Negative Breast Cancer

Triple negative is a term applied to breast cancers that do not meaningfully express the estrogen or progesterone hormone receptors or overexpress the human epidermal growth factor receptor 2 tyrosine kinase. At present, the only proven method for systemic management of triple-negative breast cancer for both early-stage and metastatic settings is cytotoxic chemotherapy. Here, we provide a comprehensive review of management strategies that are best supported by available data. We also review recent advances most likely to affect treatment of triple-negative breast cancer in the coming years with particular emphasis on targeted agents, biologics, and immunotherapy.

Efficacy of the PARP Inhibitor Veliparib with Carboplatin or as a Single Agent in Patients with Germline BRCA1- or BRCA2-Associated Metastatic Breast Cancer: California Cancer Consortium Trial NCT01149083

Purpose: We aimed to establish the MTD of the poly (ADP-ribose) (PAR) polymerase inhibitor, veliparib, in combination with carboplatin in germline BRCA1- and BRCA2- (BRCA)-associated metastatic breast cancer (MBC), to assess the efficacy of single-agent veliparib, and of the combination treatment after progression, and to correlate PAR levels with clinical outcome.Experimental Design: Phase I patients received carboplatin (AUC of 5-6, every 21 days), with escalating doses (50-20 mg) of oral twice-daily (BID) veliparib. In a companion phase II trial, patients received single-agent veliparib (400 mg BID), and upon progression, received the combination at MTD. Peripheral blood mononuclear cell PAR and serum veliparib levels were assessed and correlated with outcome.Results: Twenty-seven phase I trial patients were evaluable. Dose-limiting toxicities were nausea, dehydration, and thrombocytopenia [MTD: veliparib 150 mg po BID and carboplatin (AUC of 5)]. Response rate (RR) was 56%; 3 patients remain in complete response (CR) beyond 3 years. Progression-free survival (PFS) and overall survival (OS) were 8.7 and 18.8 months. The PFS and OS were 5.2 and 14.5 months in the 44 patients in the phase II trial, with a 14% RR in BRCA1 (n = 22) and 36% in BRCA2 (n = 22). One of 30 patients responded to the combination therapy after progression on veliparib. Higher baseline PAR was associated with clinical benefit.Conclusions: Safety and efficacy are encouraging with veliparib alone and in combination with carboplatin in BRCA-associated MBC. Lasting CRs were observed when the combination was administered first in the phase I trial. Further investigation of PAR level association with clinical outcomes is warranted. Clin Cancer Res; 23(15); 4066-76. ©2017 AACR.

Current guidelines for BRCA testing of breast cancer patients are insufficient to detect all mutation carriers

Background

Identification of BRCA mutations in breast cancer (BC) patients influences treatment and survival and may be of importance for their relatives. Testing is often restricted to women fulfilling high-risk criteria. However, there is limited knowledge of the sensitivity of such a strategy, and of the clinical aspects of BC caused by BRCA mutations in less selected BC cohorts. The aim of this report was to address these issues by evaluating the results of BRCA testing of BC patients in South-Eastern Norway.

Methods

1371 newly diagnosed BC patients were tested with sequencing and Multi Ligation Probe Amplification (MLPA). Prevalence of mutations was calculated, and BC characteristics among carriers and non-carriers compared. Sensitivity and specificity of common guidelines for BRCA testing to identify carriers was analyzed. Number of identified female mutation positive relatives was evaluated.

Results

A pathogenic BRCA mutation was identified in 3.1%. Carriers differed from non-carriers in terms of age at diagnosis, family history, grade, ER/PR-status, triple negativity (TNBC) and Ki67, but not in HER2 and TNM status. One mutation positive female relative was identified per mutation positive BC patient. Using age of onset below 40 or TNBC as criteria for testing identified 32-34% of carriers. Common guidelines for testing identified 45-90%, and testing all below 60 years identified 90%. Thirty-seven percent of carriers had a family history of cancer that would have qualified for predictive BRCA testing. A Variant of Uncertain Significance (VUS) was identified in 4.9%.

Conclusions

Mutation positive BC patients differed as a group from mutation negative. However, the commonly used guidelines for testing were insufficient to detect all mutation carriers in the BC cohort. Thirty-seven percent had a family history of cancer that would have qualified for predictive testing before they were diagnosed with BC. Based on our combined observations, we suggest it is time to discuss whether all BC patients should be offered BRCA testing, both to optimize treatment and improve survival for these women, but also to enable identification of healthy mutation carriers within their families. Health services need to be aware of referral possibility for healthy women with cancer in their family.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-017-3422-2) contains supplementary material, which is available to authorized users.

Low expression of PinX1 is associated with malignant behavior in basal-like breast cancer

Human Pinx1 protein, associated with shelterin proteins, is widely revealed as a haploinsufficient tumor suppressor. Growing evidence has manifested the deregulation of PinX1 in distinct cancers. Nonetheless, the loss status of PinX1 and its diagnostic, prognostic and clinicopathological significance in Basal-like breast cancer are still unclear. In the present study, the PinX1 expression levels of breast cancer tissues were investigated by qRT-PCR and immunoblotting assays. Then immunohistochemistry (IHC) was performed to detect PinX1 expression on a tissue microarray. The optimal threshold for PinX1 positivity was determined by receiver operating characteristic (ROC) curve analysis. To clarify the probable role of PinX1 in BLBC, the PinX1 knockout and stably over-expressed MDA-MB-231 cell lines were constructed by the CRISPR-Cas9 system and gene transfection. The association of PinX1 expression with cell proliferation, migration and apoptosis of MDA-MB-231 cells were observed by CCK-8 assay, wound healing assay, Transwell assay, flow cytometric analysis and immunoblotting of the cleaved caspase-3 protein level. Our results showed that both PinX1 mRNA and protein expression were downregulated in breast cancer tissues (P<0.05). In IHC analysis, the optimal cut-off parameter for PinX1 positive expression was 62.5% (the AUC was 0.749, P<0.01). PinX1 positivity was 76.9% (10/14) in luminal subtypes, 50% (5/10) in Her2-enriched breast cancer and 27.3% (9/33) in basal-like subtypes. Besides, in 59 invasive ductal breast carcinomas, PinX1 expression was inversely related to histology grade (P<0.05) while it was positively associated with PR status (P<0.05) and ER status (P<0.05). These results indicated that low expression of PinX1 correlated with aggressive clinicopathological significance of breast cancer, especially in the basal-like subtype. Besides, we identified that overexpression of PinX1 inhibited the proliferation rates and migration ability and increased the apoptosis rates of BLBC. Our findings demonstrated that low expression of PinX1 was associated with malignant behaviors in basal-like subtype of breast cancer. PinX1 is likely a feasible biomarker and molecular target of BLBC.

PARP1 expression drives the synergistic antitumor activity of trabectedin and PARP1 inhibitors in sarcoma preclinical models

Background

Enhancing the antitumor activity of the DNA-damaging drugs is an attractive strategy to improve current treatment options. Trabectedin is an isoquinoline alkylating agent with a peculiar mechanism of action. It binds to minor groove of DNA inducing single- and double-strand-breaks. These kinds of damage lead to the activation of PARP1, a first-line enzyme in DNA-damage response pathways. We hypothesized that PARP1 targeting could perpetuate trabectedin-induced DNA damage in tumor cells leading finally to cell death.

Methods

We investigated trabectedin and PARP1 inhibitor synergism in several tumor histotypes both in vitro and in vivo (subcutaneous and orthotopic tumor xenografts in mice). We searched for key determinants of drug synergism by comparative genomic hybridization (aCGH) and gene expression profiling (GEP) and validated their functional role.

Results

Trabectedin activated PARP1 enzyme and the combination with PARP1 inhibitors potentiated DNA damage, cell cycle arrest at G2/M checkpoint and apoptosis, if compared to single agents. Olaparib was the most active PARP1 inhibitor to combine with trabectedin and we confirmed the antitumor and antimetastatic activity of trabectedin/olaparib combination in mice models. However, we observed different degree of trabectedin/olaparib synergism among different cell lines. Namely, in DMR leiomyosarcoma models the combination was significantly more active than single agents, while in SJSA-1 osteosarcoma models no further advantage was obtained if compared to trabectedin alone. aCGH and GEP revealed that key components of DNA-repair pathways were involved in trabectedin/olaparib synergism. In particular, PARP1 expression dictated the degree of the synergism. Indeed, trabectedin/olaparib synergism was increased after PARP1 overexpression and reduced after PARP1 silencing.

Conclusions

PARP1 inhibition potentiated trabectedin activity in a PARP1-dependent manner and PARP1 expression in tumor cells might be a useful predictive biomarker that deserves clinical evaluation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-017-0652-5) contains supplementary material, which is available to authorized users.

A Phase I Study of Topotecan, Carboplatin and the PARP Inhibitor Veliparib in Acute Leukemias, Aggressive Myeloproliferative Neoplasms, and Chronic Myelomonocytic Leukemia

Purpose: The PARP inhibitor veliparib delays DNA repair and potentiates cytotoxicity of multiple classes of chemotherapy drugs, including topoisomerase I inhibitors and platinating agents. This study evaluated veliparib incorporation into leukemia induction therapy using a previously described topotecan/carboplatin backbone.Experimental Design: Employing a 3+3 trial design, we administered escalating doses of veliparib combined with topotecan + carboplatin in relapsed or refractory acute leukemias, aggressive myeloproliferative neoplasms (MPN), and chronic myelomonocytic leukemia (CMML).Results: A total of 99 patients received veliparib 10-100 mg orally twice daily on days 1-8, 1-14, or 1-21 along with continuous infusion topotecan 1.0-1.2 mg/m2/d + carboplatin 120-150 mg/m2/d on days 3-7. The MTD was veliparib 80 mg twice daily for up to 21 days with topotecan 1.2 mg/m2/d + carboplatin 150 mg/m2/d. Mucositis was dose limiting and correlated with high veliparib concentrations. The response rate was 33% overall (33/99: 14 CR, 11 CRi, 8 PR) but was 64% (14/22) for patients with antecedent or associated aggressive MPNs or CMML. Leukemias with baseline DNA repair defects, as evidenced by impaired DNA damage-induced FANCD2 monoubiquitination, had improved survival [HR = 0.56 (95% confidence interval, 0.27-0.92)]. A single 80-mg dose of veliparib, as well as veliparib in combination with topotecan + carboplatin, induced DNA damage as manifested by histone H2AX phosphorylation in CD34+ leukemia cells, with greater phosphorylation in cells from responders.Conclusions: The veliparib/topotecan/carboplatin combination warrants further investigation, particularly in patients with aggressive MPNs, CMML, and MPN- or CMML-related acute leukemias. Clin Cancer Res; 23(4); 899-907. ©2016 AACR.

PARP inhibitor increases chemosensitivity by upregulating miR-664b-5p in BRCA1-mutated triple-negative breast cancer

Emerging evidence has shown that adding poly(ADP-ribose) polymerase (PARP) inhibitors to chemotherapy regimens is superior to the control regimens alone in BRCA1-mutated triple-negative breast cancer (TNBC) patients, but their underlying mechanisms have not been fully elucidated. In this study, using miRNA microarray analysis of two BRCA1-mutated TNBC cell lines, we found that miR-664b-5p expression was increased after adding a PARP inhibitor, olaparib, to a carboplatin (CBP) plus gemcitabine (GEM) therapy regimen. Functional assays showed miR-664b-5p overexpression inhibited proliferation, migration and invasion in BRCA1-mutated TNBC cells. CCNE2 was identified as a novel functional target of miR-664b-5p, and CCNE2 knockdown revealed effects similar to those observed with miR-664b-5p overexpression. Both CCNE2 knockdown and miR-664b-5p overexpression significantly increased the chemosensitivity of BRCA1-mutated TNBC cells. In addition, in vivo studies indicated that miR-664b-5p inhibited tumour growth compared with the control in tumour xenograft models, and we also found that CCNE2 expression was inversely correlated with miR-664b-5p expression in 90 TNBC patient samples. In conclusion, miR-664b-5p functions as a tumour suppressor and has an important role in the regulation of PARP inhibitors to increase chemosensitivity by targeting CCNE2. This may be one of the possible mechanisms by which PARP inhibitors increase chemosensitivity in BRCA1-mutated TNBC.

The Landscape of Somatic Genetic Alterations in Metaplastic Breast Carcinomas

Purpose: Metaplastic breast carcinoma (MBC) is a rare and aggressive histologic type of breast cancer, predominantly of triple-negative phenotype, and characterized by the presence of malignant cells showing squamous and/or mesenchymal differentiation. We sought to define the repertoire of somatic genetic alterations and the mutational signatures of MBCs.Experimental Design: Whole-exome sequencing was performed in 35 MBCs, with 16, 10, and 9 classified as harboring chondroid, spindle, and squamous metaplasia as the predominant metaplastic component. The genomic landscape of MBCs was compared with that of triple-negative invasive ductal carcinomas of no special type (IDC-NST) from The Cancer Genome Atlas. Wnt and PI3K/AKT/mTOR pathway activity was assessed using a qPCR assay.Results: MBCs harbored complex genomes with frequent TP53 (69%) mutations. In contrast to triple-negative IDC-NSTs, MBCs more frequently harbored mutations in PIK3CA (29%), PIK3R1 (11%), ARID1A (11%), FAT1 (11%), and PTEN (11%). PIK3CA mutations were not found in MBCs with chondroid metaplasia. Compared with triple-negative IDC-NSTs, MBCs significantly more frequently harbored mutations in PI3K/AKT/mTOR pathway-related (57% vs. 22%) and canonical Wnt pathway-related (51% vs. 28%) genes. MBCs with somatic mutations in PI3K/AKT/mTOR or Wnt pathway-related genes displayed increased activity of the respective pathway.Conclusions: MBCs are genetically complex and heterogeneous, and are driven by a repertoire of somatic mutations distinct from that of triple-negative IDC-NSTs. Our study highlights the genetic basis and the importance of PI3K/AKT/mTOR and Wnt pathway dysregulation in MBCs and provides a rationale for the metaplastic phenotype and the reported responses to PI3K/AKT/mTOR inhibitors in these tumors. Clin Cancer Res; 23(14); 3859-70. ©2017 AACR.

Advances in chemical pharmacotherapy to manage advanced breast cancer

INTRODUCTION

Advanced breast cancer is still incurable. However, patients diagnosed with this fatal disease live longer. The selection of systemic therapy is mainly based on molecular subtype. The aim of management in these patients is to not only improve outcome, but also to maintain quality of life. Areas covered: In this paper we focus on available treatments and drugs under late development in the three main subtypes of breast cancer: luminal (hormone receptor positive), HER2 positive and triple negative disease. Main advances during the last years have been made in the treatment of HER2 positive breast cancer with the approval of several new targeted agents. Luminal breast cancer is also a field of active clinical research. So far triple negative breast cancer remains the subtype with the worse prognosis, even though new discoveries have been made to better understand the huge heterogeneity of this type of breast cancer. Expert opinion: Several new treatment options have recently been established in metastatic breast cancer. Side effects are sometimes cumbersome for the patient and are difficult to manage easily. Thus, identification of patients who derive the most benefit is needed. In addition, collaborative efforts should integrate the genotypic fragmentation in the management and future clinical research strategies of metastatic breast cancer patients.

The PARP inhibitor ABT-888 potentiates dacarbazine-induced cell death in carcinoids

Monoagent DNA-alkylating chemotherapies like dacarbazine are among a paucity of medical treatments for advanced carcinoid tumors, but are limited by host toxicity and intrinsic chemoresistance through the base excision repair (BER) pathway via poly (ADP-ribose) polymerase (PARP). Hence, inhibitors of PARP may potentiate DNA-damaging agents by blocking BER and DNA restoration. We show that the PARP inhibitor ABT-888 (Veliparib) enhances the cytotoxic effects of dacarbazine in carcinoids. Two human carcinoid cell lines (BON and H727) treated with a combination of ABT-888 and dacarbazine resulted in synergistic growth inhibition signified by combination indices <1 on the Chou-Talalay scale. ABT-888 administered prior to varying dacarbazine doses promoted the suppression of neuroendocrine biomarkers of malignancy ASCL1 and CgA, shown by Western analysis. ATM phosphorylation and p21^Waf1/Cip1 activation, indicative of DNA damage, were increased by ABT-888 when combined with dacarbazine treatment, suggesting BER pathway attenuation by ABT-888. PE Annexin V/7-AAD staining and sorting revealed a profound induction of apoptosis following combination treatment, which was further confirmed by increased PARP cleavage. These results demonstrate that ABT-888 synergizes dacarbazine treatment in carcinoids. Therefore, ABT-888 may help treat carcinoids unresponsive or refractory to mainstay therapies.

Randomized Trial of Oral Cyclophosphamide and Veliparib in High-Grade Serous Ovarian, Primary Peritoneal, or Fallopian Tube Cancers, or BRCA-Mutant Ovarian Cancer

PURPOSE

Veliparib, a PARP inhibitor, demonstrated clinical activity in combination with oral cyclophosphamide in patients with BRCA-mutant solid tumors in a phase I trial. To define the relative contribution of PARP inhibition to the observed clinical activity, we conducted a randomized phase II trial to determine the response rate of veliparib in combination with cyclophosphamide compared with cyclophosphamide alone in patients with pretreated BRCA-mutant ovarian cancer or in patients with pretreated primary peritoneal, fallopian tube, or high-grade serous ovarian cancers (HGSOC).

EXPERIMENTAL DESIGN

Adult patients were randomized to receive cyclophosphamide alone (50 mg orally once daily) or with veliparib (60 mg orally once daily) in 21-day cycles. Crossover to the combination was allowed at disease progression.

RESULTS

Seventy-five patients were enrolled and 72 were evaluable for response; 38 received cyclophosphamide alone and 37 the combination as their initial treatment regimen. Treatment was well tolerated. One complete response was observed in each arm, with three partial responses (PR) in the combination arm and six PRs in the cyclophosphamide alone arm. Genetic sequence and expression analyses were performed for 211 genes involved in DNA repair; none of the detected genetic alterations were significantly associated with treatment benefit.

CONCLUSION

This is the first trial that evaluated single-agent, low-dose cyclophosphamide in HGSOC, peritoneal, fallopian tube, and BRCA-mutant ovarian cancers. It was well tolerated and clinical activity was observed; the addition of veliparib at 60 mg daily did not improve either the response rate or the median progression-free survival.