Veliparib with temozolomide or carboplatin/paclitaxel versus placebo with carboplatin/paclitaxel in patients with BRCA1/2 locally recurrent/metastatic breast cancer: randomized phase II study

Talazoparib for the Treatment of Metastatic Castration-resistant Prostate Cancer: A Narrative Review

Breast and prostate cancer are among the most commonly diagnosed cancers worldwide. Recent advances in tumor sequencing and gene studies have led to a paradigm shift from treatment centered on the type of tumor to therapy more focused on specific immune phenotype markers and molecular alterations. In this review, we discuss the utility and function of talazoparib concerning prostate cancer treatment and summarize recent and planned clinical trials on talazoparib. We searched medical databases for articles relating to the use of talazoparib in prostate cancer from inception. Poly ADP ribose polymerase (PARP) is a family of 17 necessary DNA repair enzymes responsible for base excision repair, single-strand break repair, and double-strand break repair. PARP inhibitors are a class of oral targeted therapies that compete for the NAD + binding site on PARP molecules. Talazoparib, a potent PARP inhibitor, has emerged as a significant therapeutic option in the treatment of metastatic castration-resistant prostate cancer (mCRPC), particularly for patients with specific genetic alterations. Its role as a PARP inhibitor makes it a targeted therapy, focusing on cancer cells with DNA repair deficiencies. Talazoparib's role as a biomarker-directed therapy in advanced prostate cancer has been increasingly recognized. The TALAPRO-1 demonstrated durable antitumor activity in mCRPC patients. TALAPRO-2 is a notable clinical trial, specifically examining the effectiveness of Talazoparib when used in combination therapies. Current investigations demonstrate a significant improvement in survival outcomes for the patients of mCRPC, making Talazoparib a promising intervention.

Combination strategies with PARP inhibitors in BRCA-mutated triple-negative breast cancer: overcoming resistance mechanisms

Triple-negative breast cancer (TNBC) is a particularly aggressive breast cancer subtype, characterised by a higher incidence in younger women, rapid metastasis, and a generally poor prognosis. Patients with TNBC and BRCA mutations face additional therapeutic challenges due to the cancer's intrinsic resistance to conventional therapies. Poly (ADP-ribose) polymerase inhibitors (PARPis) have emerged as a promising targeted treatment for BRCA-mutated TNBC, exploiting vulnerabilities in the homologous recombination repair (HRR) pathway. However, despite initial success, the efficacy of PARPis is often compromised by the development of resistance mechanisms, including HRR restoration, stabilisation of replication forks, reduced PARP1 trapping, and drug efflux. This review explores latest breakthroughs in overcoming PARPi resistance through combination therapies. These strategies include the integration of PARPis with chemotherapy, immunotherapy, antibody-drug conjugates, and PI3K/AKT pathway inhibitors. These combinations aim to enhance the therapeutic efficacy of PARPis by targeting multiple cancer progression pathways. The review also discusses the evolving role of PARPis within the broader treatment paradigm for BRCA-mutated TNBC, emphasising the need for ongoing research and clinical trials to optimise combination strategies. By tackling the challenges associated with PARPi resistance and exploring novel combination therapies, this review sheds light on the future possibilities for improving outcomes for patients with BRCA-mutated TNBC.

Incidence and risk of endocrine and metabolic abnormalities linked to PARP inhibitors in solid tumors: a meta-analysis

BACKGROUND

Poly (ADP-ribose) polymerase inhibitors (PARPi) serve as crucial therapeutic agents in solid tumor treatment. Preclinical investigations suggest a potential protective function of PARPi against endocrine and metabolic impairments. Nevertheless, the existing body of evidence remains inconclusive on this aspect.

PURPOSE

Our aim was to evaluate the potential impact of PARPi on endocrine and metabolic disruptions in clinical trials.

DATA SOURCES

We conducted a comprehensive search across the Medline, EMBASE, PubMed, and Web of Science databases, along with the ClinicalTrials.gov registry.

STUDY SELECTION

Phase II/III randomized controlled trials (RCTs) investigating the effects of PARPi in metabolic and endocrine processes were selected for inclusion in patients with solid tumors.

DATA EXTRACTION

The primary outcomes of interest encompassed metabolic and endocrine dysfunctions.

DATA SYNTHESIS

A total of 26 trials (n = 9,590 patients) were included in our meta-analysis. Niraparib demonstrated an increased risk of any-grade hyperglycemia (OR = 2.15, 95% CI 1.28-3.62), with patients receiving PARPi for metastatic pancreatic cancer showing a higher susceptibility to any-grade hyperglycemia (OR = 1.78, 95% CI 1.04-3.04). Conversely, rucaparib exhibited a potential ameliorative effect on hyperglycemia (OR = 0.54, 95% CI 0.30-0.97). No statistically significant disparities were observed for other outcomes associated with PARPi utilization.

LIMITATIONS

Among these RCTs included, 50% were assessed as low qualities due to high risk of bias.

CONCLUSIONS

Our meta-analysis demonstrated that PARPi may exert adverse effects on endocrine and metabolic pathways. Close monitoring of hyperglycemia is recommended for patients undergoing niraparib therapy, especially those with pancreatic cancer.

TRIAL REGISTRATION

This meta-Analysis was prospectively registered in the PROSPERO database with ID CRD42023457959.

A potent Bioorganic azapodophyllotoxin derivative Suppresses tumor Progression in Triple negative breast Cancer: An Insight into its Inhibitory effect on tubulin polymerization and Disruptive effect on microtubule assembly

Triple negative breast cancer (TNBC) has long been a challenging disease owing to its high aggressive behaviour, poor prognosis and its limited treatment options. The growing demand of new therapeutics against TNBC enables us to examine the therapeutic efficiency of an emerging class of anticancer compounds, azapodophyllotoxin derivative (HTDQ), a nitrogen analogue of podophyllotoxin, using different biochemical, spectroscopic and computational approaches. The anticancer activities of HTDQ are studied by performing MTT assay in a dose depended manner on Triple negative breast cancer cells using MDA-MB-468 and MDA-MB-231 cell lines with IC50 value 937 nM and 1.13 µM respectively while demonstrating minimal effect on normal epithelial cells. The efficacy of HTDQ was further tested in 3D tumour spheroids formed by the human TNBC cell line MDA-MB468 and also the murine MMTV positive TNBC cell line 4 T1. The shrinkage that observed in the tumor spheroid clearly indicates that HTDQ remarkably decreases the growth of tumor spheroid thereby affirming its cytotoxicity. The 2D cell viability assay shows significant morphological alteration that possibly caused by the cytoskeleton disturbances. Hence the binding interaction of HTDQ with cytoskeleton protein tubulin, its effect on tubulin polymerisation as well as depolymerisation of preformed microtubules along with the conformational alternation in the protein itself have been investigated in detail. Moreover, the apoptotic effects of HTDQ have been examined using a range of apoptotic markers. HTDQ-treated cancer cells showed increased expression of cleaved PARP-1 and pro-caspase-3, suggesting activation of the apoptosis process. HTDQ also upregulated pro-apoptotic Bax expression while inhibiting anti-apoptotic Bcl2 expression, supporting its ability to induce apoptosis in cancer cells. Hence the consolidated biochemical and spectroscopic research described herein may provide enormous information to use azapodophyllotoxin as promising anticancer therapeutics for TNBC cells.

Efficacy of Adding Veliparib to Temozolomide for Patients With MGMT-Methylated Glioblastoma: A Randomized Clinical Trial

Importance

The prognosis for patients with glioblastoma is poor following standard therapy with surgical resection, radiation, temozolomide, and tumor-treating fields.

Objectives

To evaluate the combination of veliparib and temozolomide in glioblastoma based on preclinical data demonstrating significant chemosensitizing effects of the polyadenosine diphosphate-ribose polymerase 1/2 inhibitor veliparib when combined with temozolomide.

Design, Setting, and Participants

Patients with newly diagnosed glioblastoma with MGMT promoter hypermethylation who had completed concomitant radiation and temozolomide were enrolled between December 15, 2014, and December 15, 2018, in this Alliance for Clinical Trials in Oncology trial. The data for this analysis were locked on April 21, 2023.

Interventions

Patients were randomized and treated with standard adjuvant temozolomide (150-200 mg/m2 orally, days 1-5) combined with either placebo or veliparib (40 mg orally, twice daily, days 1-7) for 6 cycles.

Main Outcomes and Measures

The primary end point for the phase 3 portion of the trial was overall survival (OS).

Results

There were 322 patients randomized during the phase 2 accrual period and an additional 125 patients randomized to complete the phase 3 accrual, for a total of 447 patients in the final phase 3 analysis. The median (range) age for patients was 60 (20-85) years and 190 patients (42.5%) were female. The median OS was 24.8 months (90% CI, 22.6-27.7) for the placebo arm and 28.1 months (90% CI, 24.3-33.3) for the veliparib arm (P = .17). The difference in survival did not meet the prespecified efficacy end point. However, there was a separation of the survival curves that favored the veliparib arm over 24 to 48 months of follow-up. The experimental combination was well tolerated with an acceptable elevation in grade 3 or 4 hematologic toxic effects.

Conclusions and Relevance

This trial found that adding veliparib to adjuvant temozolomide did not significantly extend OS in patients with newly diagnosed, MGMT-hypermethylated glioblastoma.

Trial Registration

ClinicalTrials.gov Identifier: NCT02152982.

Efficacy and Safety of BRCA-targeted Therapy (Polyadenosine Diphosphate-ribose Polymerase Inhibitors) in Treatment of BRCA-mutated Breast Cancer: A Systematic Review and Meta-analysis

Breast cancer is the second leading cause of women's cancer deaths after lung cancer. Risk factors such as environment, lifestyle, and genetics contribute to its development, including mutation in the breast cancer (BRCA) gene. Polyadenosine diphosphate-ribose polymerase inhibitors (PARPi) target these mutations, benefiting patients with advanced cancers. This review summarizes PARPi' safety and efficacy in the treatment of BRCA-mutated breast cancer. PubMed, The Cochrane Library for Clinical Trials, and Science Direct, were searched for articles from inception to April 2024. Eligible articles were analyzed, and data were extracted for meta-analysis using RevMan 5.4 software with a random-effect model. Out of 430 articles identified from online databases, only 6 randomized control trials including 3610 patients were included in the analysis. PARPi therapy improved progression-free survival (hazard ratio: 0.64; 95% CI: 0.56, 0.73; P < 0.00001) and overall survival (hazard ratio: 0.84; 95% CI: 0.73, 0.98 P = 0.02), according to the analysis. In our safety analysis, the risk of adverse events was not statistically different between PARPi versus chemotherapy (relative risk [RR]: 1.08; 95% CI: 0.44, 2.68; P = 0.86), and combined PARPi and standard chemotherapy (RR: 1.00; 95% CI: 0.93, 1.07; P = 0.80). The only statistically significant difference was observed in anemia, where PARPi increased the risk of developing anemia compared with standard chemotherapy (RR: 6.17; 95% CI: 2.44, 15.58; P = 0.0001). In BRCA-mutated breast cancer, PARPi treatment shows better overall survival and progression-free survival compared with standard chemotherapy or placebo. Furthermore, PARPi, either alone or in combination therapy, does not increase the risk of adverse events in these patients, as per the meta-analysis.

Efficacy and safety of veliparib in the treatment of advanced/metastatic breast cancer: a meta-analysis of phase II and III randomized controlled trials

We conducted a meta-analysis to evaluate the efficacy and safety of veliparib in the treatment of advanced/metastatic breast cancer. Databases were searched for relevant studies till June 2023. Six RCTs involving 1912 patients were included. The pooled analysis provided evidence that veliparib-containing regimens could significantly improve the PFS (HR: 0.71; 95% CI: 0.61-0.83; p < 0.0001), OS (HR: 0.87; 95% CI: 0.76-0.99; p = 0.03), and ORR (RR: 1.52; 95% CI:1.06-2.18; p = 0.02) than those of controls for treating advanced/metastatic breast cancer. Breast cancer patients with BRCA-mutation tended to have a better PFS than the BRCA-wildtype group, and patients with TNBC tended to associated with a longer PFS than the non-TNBC group. Veliparib could significantly increase the risk of anemia, leukopenia, neutropenia, diarrhea, stomatitis, fatigue, and peripheral neuropathy. Anemia and neutropenia should be well concerned. The veliparib-containing regimen was efficacious in treating advanced/metastatic breast cancer with a controllable safety factor.

DNA damage response in breast cancer and its significant role in guiding novel precise therapies

DNA damage response (DDR) deficiency has been one of the emerging targets in treating breast cancer in recent years. On the one hand, DDR coordinates cell cycle and signal transduction, whose dysfunction may lead to cell apoptosis, genomic instability, and tumor development. Conversely, DDR deficiency is an intrinsic feature of tumors that underlies their response to treatments that inflict DNA damage. In this review, we systematically explore various mechanisms of DDR, the rationale and research advances in DDR-targeted drugs in breast cancer, and discuss the challenges in its clinical applications. Notably, poly (ADP-ribose) polymerase (PARP) inhibitors have demonstrated favorable efficacy and safety in breast cancer with high homogenous recombination deficiency (HRD) status in a series of clinical trials. Moreover, several studies on novel DDR-related molecules are actively exploring to target tumors that become resistant to PARP inhibition. Before further clinical application of new regimens or drugs, novel and standardized biomarkers are needed to develop for accurately characterizing the benefit population and predicting efficacy. Despite the promising efficacy of DDR-related treatments, challenges of off-target toxicity and drug resistance need to be addressed. Strategies to overcome drug resistance await further exploration on DDR mechanisms, and combined targeted drugs or immunotherapy will hopefully provide more precise or combined strategies and expand potential responsive populations.

Neurological toxicities with poly (ADP-ribose) polymerase inhibitors in cancer patients: a systematic review and meta-analysis

We conducted this meta-analysis to investigate neurological toxicities with poly (ADP-ribose) polymerase inhibitors (PARPis) in cancer patients. Databases were searched for randomized controlled trials (RCTs) from 1 January 2000 to 1 November 2023. Forty-six RCTs and 9529 patients were included. PARPis could increase the risk of all-grade headache [risk ratio (RR), 1.22; 95% confidence intervals (CI), 1.14-1.30; P < 0.00001], dizziness (RR, 1.40; 95% CI, 1.28-1.53; P < 0.00001), dysgeusia (RR, 1.93; 95% CI, 1.44-2.60; P < 0.0001) and insomnia (RR, 1.32; 95% CI, 1.09-1.60; P < 0.0001) in cancer patients. Headache was the most common neurological toxicity. Niraparib was associated with a higher risk of headache and insomnia, talazoparib with a higher risk of dizziness and rucaparib with a higher risk of dysgeusia. Breast cancer patients receiving PARPis have a higher risk of dysgeusia, while ovarian cancer patients are at an increased risk of insomnia. PARPis may increase the risk of mild to moderate neurological toxicities, but not severe ones.

Cisplatin in the era of PARP inhibitors and immunotherapy

Platinum compounds such as cisplatin, carboplatin and oxaliplatin are widely used in chemotherapy. Cisplatin induces cytotoxic DNA damage that blocks DNA replication and gene transcription, leading to arrest of cell proliferation. Although platinum therapy alone is effective against many tumors, cancer cells can adapt to the treatment and gain resistance. The mechanisms for cisplatin resistance are complex, including low DNA damage formation, high DNA repair capacity, changes in apoptosis signaling pathways, rewired cell metabolisms, and others. Drug resistance compromises the clinical efficacy and calls for new strategies by combining cisplatin with other therapies. Exciting progress in cancer treatment, particularly development of poly (ADP-ribose) polymerase (PARP) inhibitors and immune checkpoint inhibitors, opened a new chapter to combine cisplatin with these new cancer therapies. In this Review, we discuss how platinum synergizes with PARP inhibitors and immunotherapy to bring new hope to cancer patients.

PARP Inhibitors for Breast Cancer Treatment: A Review

Importance

Poly(adenosine diphosphate-ribose) polymerase (PARP) inhibitors have revolutionized the treatment of patients with germline BRCA1/2-associated breast cancer, representing the first targeted therapy capable of improving outcomes in patients with hereditary tumors. However, resistance to PARP inhibitors occurs in almost all patients.

Observations

This narrative review summarizes the biological rationale behind the use of PARP inhibitors in breast cancer, as well as the available evidence, recent progress, and potential future applications of these agents. Recent studies have shown that the benefit of PARP inhibitors extends beyond patients with germline BRCA1/2-associated metastatic breast cancer to patients with somatic BRCA1/2 variants and to those with germline PALB2 alterations. Moreover, these agents proved to be effective both in the metastatic and adjuvant settings. However, patients with metastatic breast cancer usually do not achieve the long-term benefit from PARP inhibitors observed in other tumor types. Mechanisms of resistance have been identified, but how to effectively target them is largely unknown. Ongoing research is investigating both novel therapeutics and new combination strategies to overcome resistance. PARP1-selective inhibitors, by sparing the hematological toxic effects induced by the PARP2 blockade, are promising agents to be combined with chemotherapy, antibody-drug conjugates, and other targeted therapies.

Conclusions and Relevance

Although the efficacy of PARP inhibitors is well established, many questions persist. Future research should focus on identifying predictive biomarkers and therapeutic strategies to overcome resistance. Integrating well-designed translational efforts into all clinical studies is thereby crucial to laying the groundwork for future insights from ongoing research.

Survival outcomes of patients with HER2/neu-positive breast cancer with germline BRCA mutations

BACKGROUND

Breast cancer (BC) with germline BRCA1/2 mutations and their association with triple-negative BC has been thoroughly investigated. However, some carriers of BRCA1/2 mutations have human epidermal growth factor receptor 2 (HER2/neu)-positive BC, which has a different targeted therapy approach, and data are scarce for this patient population. The authors sought to characterize the clinical characteristics and outcomes of patients with HER2/neu-positive BC who had germline BRCA1/2 mutations.

METHODS

This was a retrospective analysis of data from 1099 patients diagnosed with HER2/neu-positive BC who were screened for germline BRCA mutations between 1996 and 2022. Clinicopathologic features and survival rates were analyzed by BRCA mutation status. Univariate and multivariable Cox proportional hazards regression models were used to analyze the association between clinical variables and outcomes.

RESULTS

Of 1099 patients with HER2/neu-positive BC, 73 (6.6%) tested positive for BRCA1/2 mutations. Age, race, and tumor characteristics did not differ between BRCA noncarriers and carriers. At a median follow-up of 78.6 months, the 5-year recurrence-free survival rate was 85% in BRCA carriers and 87% in noncarriers (p = .79), and the 5-year overall survival rate was 94% in BRCA carriers and 94% in noncarriers (p = .78). In a multivariable model, BRCA was not associated with recurrence-free survival (hazard ratio, 0.99; 95% confidence interval, 0.51-1.90; p = .96) or overall survival (hazard ratio, 0.83; 95% confidence interval, 0.33-2.07; p = .69).

CONCLUSIONS

BRCA1/2 mutations occurred in 6.6% of patients with HER2/neu-positive BC and did not affect survival outcomes. Assessing the potential benefits of new treatment strategies, such as combining anti-HER2/neu therapies with poly(ADP-ribose) polymerase inhibitors, may lead to enhanced outcomes for these patients.

A multi-site phase I trial of Veliparib with standard radiation and temozolomide in patients with newly diagnosed glioblastoma multiforme (GBM)

PURPOSE

A multi-site Phase I trial was conducted to determine the safety, maximum tolerated dose, and pharmacokinetics (PK) of Veliparib, a Poly (ADP-ribose) polymerase [PARP] enzyme inhibitor, when administered with temozolomide (TMZ) alone and then with temozolomide and radiation (RT) in patients with newly diagnosed glioblastoma.

METHODS

Given the potential for myelosuppression when a PARP inhibitor is combined with chemotherapy, the first 6 patients accrued were given Veliparib 10 mg bid and TMZ 75 mg/m2/d daily for six weeks. If this was well tolerated, the same doses of Veliparib and TMZ would be tested along with standard radiation with plans to dose escalate the Veliparib in subsequent patient cohorts. Once a maximal tolerated dose was determined, a 78 patient phase II study was planned. Peripheral blood pharmacokinetics were assessed.

RESULTS

Twenty-four patients were enrolled. In the first 6 patients who received 6 weeks of TMZ with Veliparib only one dose limiting toxicity (DLT) occurred. The next 12 patients received 6 weeks of RT + TMZ + veliparib and 4/12 (33%) had dose limiting hematologic toxicities. As a result, Veliparib was reduced by 50% to 10 mg BID every other week, but again 3/3 patients had dose limiting hematologic toxicities. The trial was then terminated. The mean clearance (± SD) CL/F of Veliparib for the initial dose (27.0 ± 9.0 L/h, n = 16) and at steady-state for 10 mg BID (23.5 ± 10.4 L/h, n = 18) were similar. Accumulation for BID dosing was 56% (± 33%).

CONCLUSIONS

Although Veliparib 10 mg BID administered with TMZ 75 mg/m2 for six weeks was well tolerated, when this regimen was combined with standard partial brain irradiation it was severely myelosuppressive even when the dose was reduced by 50%. This study again highlights the potential of localized cranial radiotherapy to significantly increase hematologic toxicity of marginally myelosuppressive systemic therapies.

Small molecule tractable PARP inhibitors: Scaffold construction approaches, mechanistic insights and structure activity relationship

Diverse drug design strategies viz. molecular hybridization, substituent installation, scaffold hopping, isosteric replacement, high-throughput screening, induction and separation of chirality, structure modifications of phytoconstituents and use of structural templates have been exhaustively leveraged in the last decade to load the chemical toolbox of PARP inhibitors. Resultantly, numerous promising scaffolds have been pinpointed that in turn have led to the resuscitation of the credence to PARP inhibitors as cancer therapeutics. This review briefly presents the physiological functions of PARPs, the pharmacokinetics, and pharmacodynamics, and the interaction profiles of FDA-approved PARP inhibitors. Comprehensively covered is the section on the drug design strategies employed by drug discovery enthusiasts for furnishing PARP inhibitors. The impact of structural variations in the template of designed scaffolds on enzymatic and cellular activity (structure-activity relationship studies) has been discussed. The insights gained through the biological evaluation such as profiling of physicochemical properties andin vitroADME properties, PK assessments, and high-dose pharmacology are covered.

A Multi-Site Phase I Trial of Veliparib with Standard Radiation and Temozolomide in Patients with Newly Diagnosed Glioblastoma Multiforme (GBM)

Purpose

A multi-site Phase I trial was conducted to determine the safety, maximum tolerated dose, and pharmacokinetics (PK) of Veliparib, a Poly (ADP-ribose) polymerase [PARP] enzyme inhibitor, when administered with temozolomide (TMZ) alone and then with temozolomide and radiation (RT) in patients with newly diagnosed glioblastoma.

Methods

Given the potential for myelosuppression when a PARP inhibitor is combined with chemotherapy, the first 6 patients accrued were given Veliparib 10 mg bid and TMZ 75 mg/m2/d daily for six weeks. If this was well tolerated, the same doses of Veliparib and TMZ would be tested along with standard radiation with plans to dose escalate the Veliparib in subsequent patient cohorts. Once a maximal tolerated dose was determined, a 78 patient phase II study was planned. Peripheral blood pharmacokinetics were assessed.

Results

Twenty-four patients were enrolled. In the first 6 patients who received 6 weeks of TMZ with Veliparib only one dose limiting toxicity (DLT) occurred. The next 12 patients received 6 weeks of RT + TMZ + veliparib and 4/12 (33%) had dose limiting hematologic toxicities. As a result, Veliparib was reduced by 50% to 10 mg BID every other week, but again 3/3 patients had dose limiting hematologic toxicities. The trial was then terminated. The mean clearance (± SD) CL/F of Veliparib for the initial dose (27.0 ± 9.0 L/h, n = 16) and at steady-state for 10 mg BID (23.5 ± 10.4 L/h, n = 18) were similar. Accumulation for BID dosing was 56% (± 33%).

Conclusions

Although Veliparib 10 mg BID administered with TMZ 75 mg/m2 for six weeks was well tolerated, when this regimen was combined with standard partial brain irradiation it was severely myelosuppressive even when the dose was reduced by 50%. This study again highlights the potential of localized cranial radiotherapy to significantly increase hematologic toxicity of marginally myelosuppressive systemic therapies.

DNA repair biomarkers to guide usage of combined PARP inhibitors and chemotherapy: A meta-analysis and systematic review

PURPOSE

The addition of PARP inhibitors to chemotherapy has been assessed in > 80 clinical trials across multiple malignancies, on the premise that PARP inhibitors will increase chemotherapy effectiveness regardless of whether cancers have underlying disruption of DNA repair pathways. Consequently, the majority of combination therapy trials have been performed on patients without biomarker selection, despite the use of homologous recombination deficiency to dictate use of PARP inhibitors in the maintenance setting. An unresolved question is whether biomarkers are needed to identify patients who respond to combination PARP inhibitors and chemotherapy.

METHODS

A systematic literature review identified studies using PARP inhibitors in combination with chemotherapy versus chemotherapy alone, where the study included a biomarker of DNA repair function (BRCA1, BRCA2, homologous recombination deficiency test, ATM, ERCC1, SLFN11). Hazard ratios (HR) were pooled in a meta-analysis using generic inverse-variance, and fixed or random effects modelling. Subgroup analyses were conducted on biomarker selection and type of malignancy.

RESULTS

Nine studies comprising 2547 patients met the inclusion criteria. Progression-free survival (PFS) was significantly better in patients with a DNA repair biomarker (HR: 0.57, 95% CI: 0.48-0.68, p < 0.00001), but there was no benefit in patients who lacked a biomarker (HR: 0.94, 95% CI: 0.82-1.08, p = 0.38). Subgroup analysis showed that BRCA status and SLFN11 biomarkers could predict benefit, and biomarker-driven benefit occurred in ovarian, breast and small cell lung cancers. The addition of PARP inhibitors to chemotherapy was associated with increased grade 3/4 side effects, and particularly neutropenia.

CONCLUSIONS

Combination therapy only improves PFS in patients with identifiable DNA repair biomarkers. This indicates that PARP inhibitors do not sensitise patients to chemotherapy treatment, except where their cancer has a homologous recombination defect, or an alternative biomarker of altered DNA repair. While effective in patients with DNA repair biomarkers, there is a risk of high-grade haematological side-effects with the use of combination therapy. Thus, the benefit in PFS from combination therapy must be weighed against potential adverse effects, as individual arms of treatment can also confer benefit.

Enhancing the anti-tumor response by combining DNA damage repair inhibitors in the treatment of solid tumors

The anti-cancer efficacy of anti-malignancy therapies is related to DNA damage. However, DNA damage-response mechanisms can repair DNA damage, failing anti-tumor therapy. The resistance to chemotherapy, radiotherapy, and immunotherapy remains a clinical challenge. Thus, new strategies to overcome these therapeutic resistance mechanisms are needed. DNA damage repair inhibitors (DDRis) continue to be investigated, with polyadenosine diphosphate ribose polymerase inhibitors being the most studied inhibitors. Evidence of their clinical benefits and therapeutic potential in preclinical studies is growing. In addition to their potential as a monotherapy, DDRis may play an important synergistic role with other anti-cancer therapies or in reversing acquired treatment resistance. Here we review the impact of DDRis on solid tumors and the potential value of combinations of different treatment modalities with DDRis for solid tumors.

An overview of the research progress of BRCA gene mutations in breast cancer

The breast cancer susceptibility gene (BRCA) is an important tumor suppressor gene, including BRCA1 and BRCA2, a biomarker that assesses the risk of breast cancer and influences a patient's individualized treatment options. BRCA1/2 mutation (BRCAm) increases the risk of breast cancer. However, breast-conserving surgery is still an option for BRCAm, and prophylactic mastectomy and nipple-sparing mastectomy may also reduce the risk of breast cancer. BRCAm is sensitive to Poly (ADP-ribose) polymerase inhibitor (PARPi) therapy due to specific types of DNA repair defects, and its combination with other DNA damage pathway inhibitors and endocrine therapy and immunotherapy are also used for the treatment of BRCAm breast cancer. The current treatment and research progress of BRCA1/2 mutant breast cancer in this review provides a basis for the individualized treatment of patients with this type of breast cancer.

Targeting DNA damage repair precision medicine strategies in cancer

DNA repair targeted therapeutics is a promising precision medicine strategy in cancer. The development and clinical use of PARP inhibitors has transformed lives for many patients with BRCA germline deficient breast and ovarian cancer as well as platinum sensitive epithelial ovarian cancers. However, lessons learnt from the clinical use of PARP inhibitors also confirm that not all patients respond either due to intrinsic or acquired resistance. Therefore, the search for additional synthetic lethality approaches is an active area of translational and clinical research. Here, we review the current clinical state of PARP inhibitors and other evolving DNA repair targets including ATM, ATR, WEE1 inhibitors and others in cancer.

A phase 1 study of veliparib (ABT-888) plus weekly carboplatin and paclitaxel in advanced solid malignancies, with an expansion cohort in triple negative breast cancer (TNBC) (ETCTN 8620)

BACKGROUND

Veliparib is a poly-ADP-ribose polymerase (PARP) inhibitor, and it has clinical activity with every 3 weeks carboplatin and paclitaxel. In breast cancer, weekly paclitaxel is associated with improved overall survival. We aimed to determine the maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D) of veliparib with weekly carboplatin and paclitaxel as well as safety, pharmacokinetics, and preliminary clinical activity in triple negative breast cancer (TNBC).

METHODS

Patients with locally advanced/metastatic solid tumors and adequate organ function were eligible. A standard 3 + 3 dose-escalation design was followed by a TNBC expansion cohort. Veliparib doses ranging from 50 to 200 mg orally bid were tested with carboplatin (AUC 2) and paclitaxel (80 mg/m2) given weekly in a 21-day cycle. Adverse events (AE) were evaluated by CTCAE v4.0, and objective response rate (ORR) was determined by RECIST 1.1.

RESULTS

Thirty patients were enrolled, of whom 22 had TNBC. Two dose-limiting toxicities were observed. The RP2D was determined to be 150 mg PO bid veliparib with weekly carboplatin and paclitaxel 2 weeks on, 1 week off, based on hematologic toxicity requiring dose reduction in the first 5 cycles of treatment. The most common grade 3/4 AEs included neutropenia, anemia, and thrombocytopenia. PK parameters of veliparib were comparable to single-agent veliparib. In 23 patients with evaluable disease, the ORR was 65%. In 19 patients with TNBC with evaluable disease, the ORR was 63%.

CONCLUSION

Veliparib can be safely combined with weekly paclitaxel and carboplatin, and this triplet combination has promising clinical activity.

Efficacy and safety of PARP inhibitors in the treatment of BRCA-mutated breast cancer: an updated systematic review and meta-analysis of randomized controlled trials

INTRODUCTION

Poly-ADP-ribose polymerase inhibitors (PARPis) have emerged as a new class of therapeutic agents for breast cancer patients with breast cancer susceptibility gene (BRCA) mutations. However, the efficacy and toxicity of PARPis have not been clearly established.

METHODS

This study comprehensively evaluated the efficacy and safety of PARPis in patients with BRCA-mutated breast cancer. Online databases were systematically searched, and six clinical trials were included. The primary endpoint of efficacy was progression-free survival (PFS), whereas the secondary endpoints were overall survival (OS) and objective response rate (ORR). Additionally, we assessed the safety of PARPis.

RESULTS

The results of the meta-analysis showed that PARPis can effectively improve the PFS and OS in patients compared with the control group. The pooled HR (PARPi vs control groups) was 0.63 (95% CI, 0.55 - 0.73) and 0.83 (95% CI, 0.73 to -0.95) for PFS and OS, respectively. In safety, PARPis demonstrated controllable adverse reactions. There were no significant differences in overall AEs or grade ≥3 AEs between the PARP inhibitor and control arms.

CONCLUSIONS

Our results confirm the efficacy and safety of PARPis in patients with BRCA-mutated breast cancer, and more specifically clarify the efficacy of PARPis alone or in combination with other chemotherapy drugs. [Figure: see text].

Efficacy of PARP Inhibitor, Platinum, and Immunotherapy in BRCA-Mutated HER2-Negative Breast Cancer Patients: A Systematic Review and Network Meta-Analysis

The optimal treatment regimen for breast cancer patients with gBRCA mutations remains controversial given the availability of numerous options, such as platinum-based agents, polymerase inhibitors (PARPis), and other agents. We included phase II or III RCTs and estimated the HR with 95% CI for OS, PFS, and DFS, in addition to the OR with 95% CI for ORR and pCR. We determined the treatment arm rankings by P-scores. Furthermore, we carried out a subgroup analysis in TNBC and HR-positive patients. We conducted this network meta-analysis using R 4.2.0 and a random-effects model. A total of 22 RCTs were eligible, involving 4253 patients. In the pairwise comparisons, PARPi + Platinum + Chemo was better than PARPi + Chemo for OS (in whole study group and in both subgroups) as well as PFS. The ranking tests demonstrated that PARPi + Platinum + Chemo ranked first in PFS, DFS, and ORR. Platinum + Chemo showed higher OS than PARPi + Chemo. The ranking tests for PFS, DFS, and pCR indicated that, except for the best treatment (PARPi + Platinum + Chemo) containing PARPi, the second and third treatments were platinum monotherapy or platinum-based chemotherapy. In conclusion, PARPi + Platinum + Chemo might be the best regime for gBRCA-mutated BC. Platinum drugs showed more favorable efficacy than PARPi in both combination and monotherapy.

Efficacy and safety of treatment regimens for patients with metastatic, locally advanced, or recurrent breast cancer carrying BRCA1/BRCA2 pathogenic variants: A network meta-analysis

Objective

Patients with breast cancer carrying BRCA1 and BRCA2 genetic alterations show poor prognoses. However, the efficacy of pharmacotherapies for patients with advanced breast cancer carrying BRCA1/2 pathogenic variants remains unclear. This study aimed to conduct a network meta-analysis to assess the efficacy and safety of various pharmacotherapies for patients with metastatic, locally advanced, or recurrent breast cancer carrying BRCA1/BRCA2 pathogenic variants.

Methods

A literature search was conducted using Embase, PubMed, and Cochrane Library (CENTRAL), from inception to 11^th May 2022. The references of included articles were screened to identify relevant literature. This network meta-analysis included patients with metastatic locally advanced or recurrent breast cancer who received pharmacotherapy and carried deleterious variants of BRCA1/2. The Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines were followed for conducting and reporting this systematic meta-analysis. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) method was employed to evaluate evidential certainty. Frequentist random-effect model was applied. Results of objective response rate (ORR), progression-free survival (PFS), overall survival (OS), and rates of any-grade adverse events were presented.

Results

Nine randomized controlled trials were obtained comprising six treatment regimens, including 1912 patients with pathogenic variants of BRCA1 and BRCA2. The orchestration of PARP inhibitors with platinum-based chemotherapy was found to be the most effective with a pooled odds ratio (OR) of 3.52 (95% CI 2.14, 5.78) for ORR; 1.53 (1.34,1.76), 3.05 (1.79, 5.19), and 5.80 (1.42, 23.77) for 3-, 12-, and 24-month PFS, respectively, and 1.04 (1.00, 1.07), 1.76 (1.25, 2.49) and 2.31 (1.41, 3.77) for 3-, 12-, and 36-month OS, respectively compared to those receiving non-platinum-based chemotherapy. However, it posed an elevated risk of some adverse events. Platinum-based chemotherapy alone or PARP inhibitors markedly improved ORR, PFS, and OS compared to non-platinum-based chemotherapy. Interestingly, platinum-based chemotherapy surpassed PARP inhibitors in terms of efficacy. Evidence on programmed death-ligand 1(PD-L1) inhibitors and sacituzumab govitecan (SG) suggested low quality and insignificant results.

Conclusions

Among all treatment regimens, PARP inhibitors with platinum exhibited the best efficacy, although with a trade-off of elevated risk of some types of adverse events. Future research on direct comparisons between different treatment regimens specifically targeting patients with breast cancer carrying BRCA1/2 pathogenic variants with a pre-specified adequate sample size is warranted.

Cisplatin with veliparib or placebo in metastatic triple-negative breast cancer and BRCA mutation-associated breast cancer (S1416): a randomised, double-blind, placebo-controlled, phase 2 trial

BACKGROUND

Poly(ADP-ribose) polymerase (PARP) inhibitors are effective in germline BRCA1 or BRCA2 (BRCA1/2) mutation-associated metastatic breast cancer. However, studies evaluating PARP inhibitors plus platinum-based chemotherapy in germline BRCA1/2-wildtype triple-negative breast cancer are scarce. A large proportion of germline BRCA1/2-wildtype triple-negative breast cancer shows homologous recombination deficiency (HRD), resulting in a BRCA-like phenotype that might render sensitivity to PARP inhibitors. The S1416 trial assessed the efficacy of cisplatin combined with the PARP inhibitor veliparib in three predefined groups of metastatic breast cancer: germline BRCA1/2-mutated, BRCA-like, and non-BRCA-like.

METHODS

S1416 was a randomised, double-blind, placebo-controlled, phase 2 trial conducted at 154 community and academic clinical sites across the USA. Eligible patients aged 18 years or older had metastatic or recurrent triple-negative breast cancer or germline BRCA1/2-associated metastatic or recurrent breast cancer, an Eastern Cooperative Oncology Group performance status of 0-2, and had received up to one line of chemotherapy for metastatic disease. Patients were randomly assigned (1:1) via the National Clinical Trials Network open interactive system with dynamic balancing on number of previous cytotoxic regimens for metastatic disease to receive intravenous cisplatin (75 mg/m2, day 1) combined with either veliparib or matching placebo (300 mg orally twice a day, days 1-14) on a 21-day cycle. Investigators, patients, and the sponsors were masked to treatment assignment; the study statisticians were unmasked. Central testing after ran domisation classified patients as having mutated or wildtype germline BRCA1/2. A biomarker panel established a priori was used to classify patients with wildtype germline BRCA1/2 into BRCA-like and non-BRCA-like phenotype groups, with BRCA-like status based on at least one of the biomarkers: genomic instability score (≥42), somatic BRCA1/2 mutations, BRCA1 promoter methylation, or non-BRCA1/2 homologous recombination repair germline mutations. The primary endpoint was investigator-assessed progression-free survival, analysed separately for the three predefined biomarker groups with a prespecified α value for each analysis. Efficacy analyses were done by intention to treat and included all eligible patients. Safety analyses of toxicities attributed to treatment included all patients who received at least one dose of veliparib or placebo. The study is ongoing and registered with ClinicalTrials.gov, NCT02595905.

FINDINGS

Between July 7, 2016, and June 15, 2019, 335 patients were enrolled and randomly assigned. 320 patients (n=162 to cisplatin plus veliparib, all women; and n=158 to cisplatin plus placebo, 157 women and one man) were eligible for efficacy evaluation. 247 patients were classified into the three biomarker groups: germline BRCA1/2-mutated (n=37), BRCA-like (n=101), and non-BRCA-like (n=109). 73 patients could not be classified due to missing biomarker information. Median follow-up was 11·1 months (IQR 5·6-20·8). In the germline BRCA1/2-mutated group, median progression-free survival was 6·2 months (95% CI 2·3-9·2) in the cisplatin plus veliparib group and 6·4 months (4·3-8·2) in the cisplatin plus placebo group (HR 0·79 [95% CI 0·38-1·67]; log-rank p=0·54). In the BRCA-like group, median progression-free survival was 5·9 months (95% CI 4·3-7·8) in the cisplatin plus veliparib group versus 4·2 months (2·3-5·0) in the cisplatin plus placebo group (HR 0·57 [95% CI 0·37-0·88]; p=0·010). In the non-BRCA-like group, median progression-free survival was 4·0 months (95% CI 2·5-4·7) in the cisplatin plus veliparib group versus 3·0 months (2·2-4·4) in the cisplatin plus placebo group (HR 0·89 [95% CI 0·60-1·33]; p=0·57). The most common grade 3 or worse adverse events attributed to treatment were neutropenia (71 [46%] of 155 patients in the cisplatin plus veliparib group vs 29 [20%] of 147 in the cisplatin plus placebo group), leukopenia (42 [27%] vs 11 [7%]), anaemia (35 [23%] vs 12 [8%]), and thrombocytopenia (29 [19%] vs four [3%]). Serious adverse events attributed to treatment occurred in 48 (31%) patients in the cisplatin plus veliparib group and 53 (36%) patients in the cisplatin plus placebo group. Treatment-related adverse events led to death in one patient in the cisplatin plus veliparib group (sepsis) and one patient in the cisplatin plus placebo group (acute kidney injury due to cisplatin plus heart failure from previous doxorubicin exposure).

INTERPRETATION

The addition of veliparib to cisplatin significantly improved progression-free survival in patients with BRCA-like metastatic triple-negative breast cancer, but not in patients with non-BRCA-like metastatic breast cancer. PARP inhibitors combined with platinum-based chemotherapy should be explored further in BRCA-like triple-negative breast cancer.

FUNDING

National Cancer Institute and National Institute of General Medical Sciences (US National Institutes of Health); AbbVie; Myriad Genetics; the Biomarker, Imaging, and Quality of Life Studies Funding Program (awarded by the National Cancer Institute); and The University of Kansas Cancer Center.

Systemic Therapy for Hereditary Breast Cancers

Approximately 5% to 10% of all breast cancers are hereditary; many of which are caused by pathogenic variants in genes required for homologous recombination, including BRCA1 and BRCA2. Here we discuss systemic treatment for such breast cancers, including approved chemotherapeutic approaches and also targeted treatment approaches using poly-(ADP ribose) polymerase inhibitors. We also discuss experimental approaches to treating hereditary breast cancer, including new small molecule DNA repair inhibitors and also immunomodulatory agents. Finally, we discuss how drug resistance emerges in patients with hereditary breast cancer, how this might be delayed or prevented, and how biomarker-adapted treatment is molding the future management of hereditary breast cancer.

Incidence and risk of hypertension associated with PARP inhibitors in cancer patients: a systematic review and meta-analysis

OBJECTIVE

To analyze the incidence and risk of hypertension associated with poly(adenosine diphosphate-ribose) polymerase (PARP) inhibitors in cancer patients and provide reference for clinicians.

METHODS

We used R software to conduct a meta-analysis of phase II/III randomized controlled trials (RCT) on PARP inhibitors for cancer treatment published in PubMed, Embase, Clinical Trials, Cochrane Library and Web of Science from inception to July 29th, 2022.

RESULTS

We included 32 RCTs with 10,654 participants for this meta-analysis. For total PARP inhibitors, the incidence and risk ratio of all-grade hypertension were 12% and 1.22 (95% CI: 0.91-1.65, P = 0.19, I² = 81%), and the incidence and risk ratio of grade 3-4 hypertension were 4% and 1.24 (95% CI: 0.74-2.08, P = 0.42, I² = 68%). Compared with the control group, the niraparib group, olaparib 800 mg/day group, and olaparib plus cediranib group increased the risk of any grade and grade 3-4 hypertension, while the veliparib group and rucaparib group did not increase the risk of any grade and grade 3-4 hypertension, and olaparib 200 mg-600 mg/day group (exclude olaparib plus cediranib regime) reduced the risk of any grade and grade 3-4 hypertension.

CONCLUSION

Olaparib 200-600 mg/day (excluding olaparib plus cediranib regimen) may be the most suitable PARP inhibitor for cancer patients with high risk of hypertension, followed by veliparib and rucaparib. Niraparib, olaparib 800 mg/day and olaparib combined with cediranib may increase the risk of developing hypertension in cancer patients, clinicians should strengthen the monitoring of blood pressure in cancer patients and give medication in severe cases.

Combining Poly (ADP-Ribose) Polymerase (PARP) Inhibitors with Chemotherapeutic Agents: Promise and Challenges

Better understanding of molecular drivers and dysregulated pathways has furthered the concept of precision oncology and rational drug development. The role of DNA damage response (DDR) pathways has been extensively studied in carcinogenesis and as potential therapeutic targets to improve response to chemotherapy or overcome resistance. Treatment with small molecule inhibitors of PARP has resulted in clinical response and conferred survival benefit to patients with ovarian cancer, BRCA-mutant breast cancer, HRD-deficient prostate cancer and BRCA-mutant pancreatic cancer, leading to US Food and Drug Administration (FDA) approvals. However, the observed clinical benefit with single agent PARP inhibitors is limited to few tumor types within the relevant genetic context. Since DDR pathways are essential for repair of damage caused by cytotoxic agents, PARP inhibitors have been evaluated in combination with various chemotherapeutic agents to broaden the therapeutic application of this class of drugs. In this chapter, we discuss the combination of PARP inhibitors with different chemotherapeutics agents, clinical experience to date, lessons learnt, and future directions for this approach.

Evolving DNA repair synthetic lethality targets in cancer

DNA damage signaling response and repair (DDR) is a critical defense mechanism against genomic instability. Impaired DNA repair capacity is an important risk factor for cancer development. On the other hand, up-regulation of DDR mechanisms is a feature of cancer chemotherapy and radiotherapy resistance. Advances in our understanding of DDR and its complex role in cancer has led to several translational DNA repair-targeted investigations culminating in clinically viable precision oncology strategy using poly(ADP-ribose) polymerase (PARP) inhibitors in breast, ovarian, pancreatic, and prostate cancers. While PARP directed synthetic lethality has improved outcomes for many patients, the lack of sustained clinical response and the development of resistance pose significant clinical challenges. Therefore, the search for additional DDR-directed drug targets and novel synthetic lethality approaches is highly desirable and is an area of intense preclinical and clinical investigation. Here, we provide an overview of the mammalian DNA repair pathways and then focus on current state of PARP inhibitors (PARPi) and other emerging DNA repair inhibitors for synthetic lethality in cancer.

NAD+ metabolism in peripheral neuropathic pain

Nicotinamide adenine dinucleotide (NAD⁺) is an omnipresent metabolite that participates in redox reactions. Multiple NAD⁺-consuming enzymes are implicated in numerous biological processes, including transcription, signaling, and cell survival. Multiple pieces of evidence have demonstrated that NAD⁺-consuming enzymes, including poly(ADP-ribose) polymerases (PARPs), sirtuins (SIRTs), and sterile alpha and TIR motif-containing 1 (SARM1), play major roles in peripheral neuropathic pain of various etiologies. These NAD⁺ consumers primarily participate in peripheral neuropathic pain via mechanisms such as mitochondrial dysfunction, oxidative stress, and inflammation. Furthermore, NAD⁺ synthase and nicotinamide phosphoribosyltransferase (NAMPT) have recently been found to contribute to the regulation of pain. Here, we review the evidence indicating the involvement of NAD⁺ metabolism in the pathological mechanisms of peripheral neuropathic pain. Advanced understanding of the molecular and cellular mechanisms associated with NAD⁺ in peripheral neuropathic pain will facilitate the development of novel treatment options for diverse types of peripheral neuropathic pain.

The triple negative breast cancer drugs graveyard: a review of failed clinical trials 2017-2022

INTRODUCTION

Triple-negative breast cancer (TNBC) accounts for 15-20% of breast cancers (BC) and has the worst prognosis. It is characterized by the absence of both hormone receptor (HR) and human epidermal growth factor receptor 2 (HER2). TNBC has more limited therapeutic options compared to other subtypes, meaning that there is still a long way to go to discover target treatments.

AREAS COVERED

Our review aims to summarize phase II/III clinical trials enrolling patients with TNBC that have been published between 2017 and 2022 but failed to reach their primary endpoint. We here try to emphasize the limitations and weaknesses noted in negative studies and to point out unexpected results which might be useful to enhance the therapeutic approach to TNBC disease.

EXPERT OPINION

A deeper understanding of the mechanisms behind TNBC heterogeneity allowed to enhance the knowledge of new prognostic and predictive biomarkers of response. However, it is also through several failed clinical trials that we were able to define new therapeutic approaches which improved TNBC patients' clinical outcomes. Nowadays, we still need to overcome several difficulties to fully recognize different intracellular and extracellular pathways that crosstalk in TNBC and the mechanisms of resistance to identify novel tailored-patients' therapies.

PARP Inhibitors for Breast Cancer: Germline BRCA1/2 and Beyond

Simple Summary

Poly-adenosine diphosphate ribose polymerase (PARP) inhibitors (PARPi) are effective against tumors with mutations in DNA repair genes, most commonly in the BRCA1 and BRCA2 genes. Because these tumors are unable to repair their DNA, PARPi have been used to target DNA repair pathways and are useful in the treatment of breast cancers with some of these alterations. There are two FDA-approved PARPi for patients with breast cancer—olaparib and talazoparib. The data on olaparib and talazoparib in the treatment of breast cancer are summarized in this review, and we also explore potential future applications of PARPi beyond inherited BRCA mutations.

Abstract

Poly-adenosine diphosphate ribose polymerase (PARP) inhibitors (PARPi) are approved for BRCA1/2 carriers with HER2-negative breast cancer in the adjuvant setting with a high risk of recurrence as well as the metastatic setting. However, the indications for PARPi are broader for patients with other cancer types (e.g., prostate and ovarian cancer), involving additional biomarkers (e.g., ATM, PALB2, and CHEK) and genomic instability scores. Herein, we summarize the data on PARPi and breast cancer and discuss their use beyond BRCA carriers.

Case Report: Fluzoparib for multiple lines of chemotherapy refractory in metastatic cutaneous squamous cell carcinoma with BRCA2 pathogenic mutation

Background: Poly ADP-ribose polymerase inhibitors (PARPis) are widely used for patients with BRCA1/2 mutations. However, until now, there is no available evidence reported for the efficiency of PARPis in cutaneous squamous cell carcinoma (cSCC).

Case presentation: We presented a case of a 40-year-old man diagnosed with metastatic cSCC, relapsing after multiple lines of chemotherapy. Liquid biopsy detected a BRCA2 pathogenic germline mutation (c.3109C > T), indicating PARPis might be effective for this patient. The patient achieved tumor stability, and progression-free survival was five months without severe adverse effects after taking fluzoparib.

Conclusion: This result confirmed that PARPis were effective for metastatic cSCC patients with germline BRCA2 pathogenic mutations and provided a new treatment option for this group of patients.

Does Molecular Profiling of KRAS-Mutant Non-Squamous Non-Small Cell Lung Cancer (NSCLC) Help in Treatment Strategy Planning?

Background: Several studies suggest that patients with KRAS-mutant NSCLC fail to benefit from standard systemic therapies and do not respond to EGFR inhibitors. Most recently, KRAS 12c data suggest specific treatment for improving ORR and OS. There is a clear need for therapies specifically developed for these patients. Moreover, data that might be suggestive of a response to specific therapies, such as BRCA1, are needed, and two mutations that were studied in other malignancies show more response to PARP inhibitors. Molecular profiling has the potential to identify other potential targets that may provide better treatment and novel targeted therapy for KRAS-mutated NSCLC. Methods: We purified RNA from archived tissues of patients with stage I and II NSCLC with wild-type (wt) and mutant (mt) KRAS tumors; paired normal tissue adjacent to the tumor from 20 and 17 patients, respectively, and assessed, using real-time reverse transcriptase−polymerase chain reaction (RT-PCR), the expression of four genes involved in DNA synthesis and repair, including thymidylate synthase (TS), BRCA1, ECCR1, RAP80, and the proto-oncogene SRC. Additionally, we assessed the expression of PD-L1 in mt KRAS tumors with immunohistochemistry using an antibody against PD-L1. Results: Our results show that in mtKRAS tumors, the level of expression of ERCC1, TS, and SRC was significantly increased in comparison to paired normal lung tissue (p ≤ 0.04). The expression of BRCA1 and RAP80 was similar in both mt KRAS tumors and paired normal tissue. Furthermore, the expression of BRCA1, TS, and SRC was significantly increased in wt KRAS tumors relative to their expression in the normal lung tissue (p < 0.044). The expression of ERCC1 and RAP80 was similar in wt KRAS tumors and paired normal tissue. Interestingly, SRC expression in mtKRAS tumors was decreased in comparison to wt KRAS tumors. Notably, there was an expression of PD-L1 in the tumor and stromal cells in a few (5 out of 20) mtKRAS tumors. Our results suggest that a greater ERCC1 expression in mt KRAS tumors might increase platinum resistance in this group of patients, whereas the greater expression of BRCA1 in wt KRAS tumor might be suggestive of the sensitivity of taxanes. Our data also suggest that the combination of an SRC inhibitor with a TS inhibitor, such as pemetrexed, might improve the outcome of patients with NSCLC and in particular, patients with wt KRAS tumors. PD-L1 expression in tumors, and especially stromal cells, suggests a better outcome. Conclusion: mt KRAS NSCLC patients might benefit from a treatment strategy that targets KRAS in combination with therapeutic agents based on pharmacogenomic markers, such as SRC and BRCA1. mtKRAS tumors are likely to be platinum-, taxane-, and pemetrexed-resistant, as well as having a low level of PD-L1 expression; thus, they are less likely to receive single-agent immunotherapy, such as pembrolizumab, as the first-line therapy. wt KRAS tumors with BRCA1 positivity tend to be sensitive to taxane therapy and, potentially, platinum. Our results suggest the need to develop targeted therapies for KRAS-mutant NSCLC or combine the targeting of oncogenic KRAS in addition to other therapeutic agents specific to the molecular profile of the tumor.

Functions of Breast Cancer Predisposition Genes: Implications for Clinical Management

Approximately 5–10% of all breast cancer (BC) cases are caused by germline pathogenic variants (GPVs) in various cancer predisposition genes (CPGs). The most common contributors to hereditary BC are BRCA1 and BRCA2, which are associated with hereditary breast and ovarian cancer (HBOC). ATM, BARD1, CHEK2, PALB2, RAD51C, and RAD51D have also been recognized as CPGs with a high to moderate risk of BC. Primary and secondary cancer prevention strategies have been established for HBOC patients; however, optimal preventive strategies for most hereditary BCs have not yet been established. Most BC-associated CPGs participate in DNA damage repair pathways and cell cycle checkpoint mechanisms, and function jointly in such cascades; therefore, a fundamental understanding of the disease drivers in such cascades can facilitate the accurate estimation of the genetic risk of developing BC and the selection of appropriate preventive and therapeutic strategies to manage hereditary BCs. Herein, we review the functions of key BC-associated CPGs and strategies for the clinical management in individuals harboring the GPVs of such genes.

Opinion: PARP inhibitors in cancer-what do we still need to know?

PARP inhibitors (PARPi) have been demonstrated to exhibit profound anti-tumour activity in individuals whose cancers have a defect in the homologous recombination DNA repair pathway. Here, we describe the current consensus as to how PARPi work and how drug resistance to these agents emerges. We discuss the need to refine the current repertoire of clinical-grade companion biomarkers to be used with PARPi, so that patient stratification can be improved, the early emergence of drug resistance can be detected and dose-limiting toxicity can be predicted. We also highlight current thoughts about how PARPi resistance might be treated.

Analysis of the Clinical Advancements for BRCA-Related Malignancies Highlights the Lack of Treatment Evidence for BRCA-Positive Male Breast Cancer

Male breast cancer (MBC) is a rare disease that accounts for less than 1% of all breast cancers and male malignancies. Despite recognised clinico-pathological and molecular differences to female breast cancer (FBC), the clinical management of MBC follows established FBC treatment strategies. Loss of function mutations in the DNA damage response genes BRCA1 and BRCA2, have been strongly implicated in the pathogenesis of MBC. While there have been extensive clinical advancements in other BRCA-related malignancies, including FBC, improvements in MBC remain stagnant. Here we present a review that highlights the lack of treatment evidence for BRCA-related MBC and the required national and global collaborative effort to address this unmet need. In doing so, we summarise the transformative clinical advancements with poly(ADP-ribose) polymerase (PARP) inhibitors in other BRCA-related cancers namely, FBC and prostate cancer.

Heterogeneity of triple-negative breast cancer: understanding the Daedalian labyrinth and how it could reveal new drug targets

INTRODUCTION

Triple-negative breast cancer (TNBC) is considered the most aggressive breast cancer subtype with the least favorable outcomes. However, recent research efforts have generated an enhanced knowledge of the biology of the disease and have provided a new, more comprehensive understanding of the multifaceted ecosystem that underpins TNBC.

AREAS COVERED

In this review, the authors illustrate the principal biological characteristics of TNBC, the molecular driver alterations, targetable genes, and the biomarkers of immune engagement that have been identified across the subgroups of TNBC. Accordingly, the authors summarize the landscape of the innovative and investigative biomarker-driven therapeutic options in TNBC that emerge from the unique biological basis of the disease.

EXPERT OPINION

The therapeutic setting of TNBC is rapidly evolving. An enriched understanding of the tumor spatial and temporal heterogeneity and the surrounding microenvironment of this complex disease can effectively support the development of novel and tailored opportunities of treatment.

Associations with response to Poly(ADP-ribose) Polymerase (PARP) inhibitors in patients with metastatic breast cancer

PARP inhibitors (PARPi) have modest antitumor activity in patients with advanced breast cancer and mutation in BRCA. It is unclear whether some subgroups derive greater benefit from treatment. MEDLINE and EMBASE were searched from inception to March 2021 to identify trials of PARPi in patients with metastatic breast cancer. Objective response rate (ORR) and clinical benefit rate (CBR) to PARPi were extracted and pooled in a meta-analysis using the Mantel Haenszel random effects model. Meta-regression explored the influence of patient and tumor characteristics on ORR and CBR. For randomized trials, hazard ratio comparing PARPi to control therapy were pooled using inverse variance and random effects. Analysis included 43 studies comprising 2409 patients. Among these, 1798 (75%) patients had BRCA mutations and 1146 (48%) were triple negative. In 10 studies (28%; n = 680 patients), the PARPi was given in combination with platinum-based chemotherapy. Weighted mean ORR was 45%; 64% when combined with platinum vs 37% with PARPi monotherapy (p < 0.001). Previous platinum-based chemotherapy was associated with lower ORR (p = 0.02). Compared to standard chemotherapy, progression-free survival was improved (HR 0.64, p < 0.001), but there was no difference in overall survival (HR 0.87, p = 0.06). There were no differences in ORR or CBR between BRCA1 and BRCA2 mutations. PARPi are more active in combination with platinum than as monotherapy, with lower response if given as monotherapy after platinum exposure. Significant improvements in ORR translated to modest improvement in progression-free, but not overall survival. There was no association between ORR and BRCA mutations.

Benefit-risk trade-offs in treatment choice in advanced HER2 negative breast cancer: patient and oncologist perspectives

Objective: To evaluate which treatment attributes US patients and oncologists prioritize in HER2 negative advanced breast cancer (ABC). Methods: Preferences were assessed via a discrete choice experiment. Also, treatment goal statements were rated on an agreement scale. Results: Patients (n = 169) most valued improving overall survival (OS), followed by improving nausea and neuropathy. Oncologists (n = 117) most valued improving OS, followed by neuropathy and progression-free survival. Regarding treatment goals, oncologists (67%) perceived that patients are more focused on efficacy than quality of life; fewer patients (29%) agreed with this statement; 81% of oncologists and 51% of patients agreed that patients prefer oral treatment. Conclusion: Patients and oncologists were willing to accept increases in toxicities in exchange for efficacy improvements in HER2 negative ABC.

Curcumin sensitizes carboplatin treatment in triple negative breast cancer through reactive oxygen species induced DNA repair pathway

BACKGROUND

As patients with triple-negative breast cancer (TNBC) have a very weak response to hormone inhibition or anti-HER2 therapy, traditional chemotherapy is commonly used in these patients. Recently, carboplatin has been approved for the clinical treatment of TNBC. However, several patients exhibit resistance to carboplatin treatment. Therefore, strategies to enhance the antitumor effect of carboplatin need to be explored. In our study, we investigated the function of curcumin in increasing the response to carboplatin.

METHODS AND RESULTS

MTT and colony formation assays were used to evaluate cell viability after carboplatin and curcumin treatment. In addition, we conducted flow cytometric and Western blot analyses to examine cellular apoptosis. Subsequently, molecular and biochemical experiments were used to explore the mechanism by which curcumin sensitized TNBC to carboplatin treatment. We demonstrated that different TNBC cells responded differently to carboplatin. Low-dose carboplatin killed CAL-51 cells but barely influenced CAL-51-R and MDA-MB-231 cells. To improve the sensitivity of resistant TNBC cells to carboplatin, combined treatment with curcumin was applied and was found to inhibit proliferation and induce apoptosis. Mechanistically, curcumin exerted its anticancer effect by increasing reactive oxygen species (ROS) production, which downregulated the DNA repair protein RAD51, leading to upregulation of γH2AX. As expected, ROS scavenger NAC reversed the inhibitory effect on growth and DNA repair pathway activity mediated by curcumin.

CONCLUSION

Collectively, our data demonstrate that curcumin sensitizes TNBC to the anticancer effect of carboplatin by increasing ROS-induced DNA damage, thus providing an effective combination treatment strategy for TNBC.

Perspectives on the role of breast cancer susceptibility gene in breast cancer

PURPOSE

Breast cancer susceptibility gene 1/2 can repair damaged DNA through homologous recombination. Besides, the local immune microenvironment of breast cancer is closely linked to the prognosis of patients. But the relationship of breast cancer susceptibility gene 1/2 expression and local immunosuppressive microenvironment in breast cancer is not clear. The aim of this study was to discuss the correlation between them.

METHODS

The fresh primary breast tumors and paired normal tissues of 156 cases of breast cancer patients as well as peripheral blood of 156 cases among them in Tianjin Medical University Cancer Institute and Hospital from January 2014 to October 2018 were collected. The association between breast cancer susceptibility gene 1/2 germline mutation and immune status of microenvironment in situ was analyzed.

RESULTS

The results indicated that the germline mutation of breast cancer susceptibility gene 1/2 was inconsistent with the breast cancer susceptibility gene 1/2 protein expression, and the proportion of immune cells in patients with negative expression of breast cancer susceptibility gene 1/2 protein was higher than patients with positive expression of breast cancer susceptibility gene 1/2 protein (p < 0.05). And the expression of programmed cell death protein 1, cytotoxic T-Lymphocyte Antigen 4, programmed death ligand-1 of CD3⁺ T cells in patients with negative expression of breast cancer susceptibility gene 1/2 protein was higher than patients with positive expression of breast cancer susceptibility gene 1/2 protein (p < 0.05). The breast cancer susceptibility gene 1 protein expression was significantly correlated with family history of breast cancer patients (p = 0.006), local lymph node metastases (p = 0.001), and TNM staging (p ≤ 0.001). The breast cancer susceptibility gene 2 protein expression was significantly related to local lymph node metastases (p ≤ 0.001), III stage rate(p = 0.003) and molecular subtyping (p ≤ 0.001). Besides, the 5 years disease free survival was worse for G1 group and pathological III stage patients than other groups and other TNM stage patients.

CONCLUSION

In short, the immune therapy may be a potential therapy method for breast cancer patients with negative expression of breast cancer susceptibility gene 1/2 protein.

Veliparib for the treatment of solid malignancies

OBJECTIVE

Veliparib is a poly adenosine diphosphate ribose polymerase (PARP) -1 and -2 inhibitor with chemo-sensitizing and anticancer activities that has shown promising results in early-phase trials. The aim of this comprehensive review is to summarise the profile of veliparib and to provide an overview of its early clinical investigations.

DATA SOURCES

Details of all the completed trials evaluating the profile of veliparib were identified from ClinicalTrials.gov with the relevant keywords. Furthermore, databases such as Google Scholar and PubMed were searched using the National Clinical Trial (NCT) number to retrieve publications of results not listed in the trial registry.

DATA SUMMARY

A total of 25 completed clinical trials indicating the use of veliparib in solid malignancies were identified. The results showed that veliparib is well tolerated, both as a single agent and in combination with standard chemotherapy doses. Being a broad-spectrum potentiator of DNA-damaging agents and radiation, it has shown to improve the clinical outcomes, particularly in solid tumors like ovarian cancer, breast cancer and lung cancer.

CONCLUSIONS

The results from clinical trials indicate that veliparib can be an excellent therapeutic strategy for BRCA mutation associated cancers and tumors bearing deficiencies in the HR pathway as well. Further studies establishing the dosing, sequence of therapy, extended use and compatibility with various anti-cancer drugs are warranted to define its exact role in cancer therapy.

Platinum and Taxane Based Adjuvant and Neoadjuvant Chemotherapy in Early Triple-Negative Breast Cancer: A Narrative Review

Platinum (Pt) derivatives such as cisplatin and carboplatin are the class of drugs with proven activity against triple-negative breast cancer (TNBC). This is due to the ability of Pt compounds to interfere with the DNA repair mechanisms of the neoplastic cells. Taxanes have been efficacious against estrogen receptor-negative tumors and act by disruption of microtubule function. Due to their distinct mechanisms of action and routes of metabolism, the combination of the Pt agents and taxanes results in reduced systemic toxicity, which is ideal for treating TNBC. Also, the sensitivity of BRCA1-mutated cells to taxanes remains unsolved as in vitro evidence indicates resistance against taxanes due to BRCA1 mutations. Recent evidence suggests that the combination of carboplatin and paclitaxel resulted in better pathological complete response (pCR) in patients with TNBC, both in neoadjuvant and adjuvant settings. In vitro studies showed sequential dependency and optimal time scheduling of Pt- and taxane-based chemotherapy. Also, combining carboplatin with docetaxel in the NAC regimen yields an excellent pCR in patients with BRCA-associated and wild-type TNBC. TNBC is a therapeutic challenge that can be tackled by identifying new therapeutic sub-targets and specific cross-sections that can be benefitted from the addition of Pt- and taxane-based chemotherapy. This review summarizes the merits as well as the mechanism of Pt- and taxane-based adjuvant and neoadjuvant chemotherapies in early TNBC from the available and ongoing clinical studies.

Safety and efficacy of veliparib plus carboplatin/paclitaxel in patients with HER2-negative metastatic or locally advanced breast cancer: subgroup analyses by germline BRCA1/2 mutations and hormone receptor status from the phase-3 BROCADE3 trial

Purpose

To evaluate efficacy and safety of veliparib combined with carboplatin/paclitaxel in patients with advanced human epidermal growth factor receptor 2 (HER2)-negative, germline BRCA (gBRCA)-associated breast cancer defined by hormone receptor (HR) and gBRCA1/2 mutation status.

Patients and Methods

In this phase-3, double-blind, placebo-controlled trial, patients (N = 509) with advanced HER2-negative breast cancer and gBRCA1/2 mutations were randomized 2:1 to receive veliparib plus carboplatin/paclitaxel or placebo plus carboplatin/paclitaxel. Patients who discontinued chemotherapy prior to disease progression continued receiving blinded veliparib/placebo monotherapy. The primary endpoint was investigator-assessed progression-free survival (PFS). Subgroup analyses of PFS stratified by HR and gBRCA1/2 mutation status were prespecified.

Results

In the intention-to-treat population, there were similar proportions of patients with gBRCA1 versus gBRCA2 mutations (51% vs 49%) and HR+ disease versus triple-negative breast cancer (TNBC) (52% vs 48%). Median PFS was longer in the veliparib arm compared with the placebo arm for all subgroups (HR+: 13.0 vs 12.5 months, hazard ratio (95% confidence interval (CI)): 0.69 (0.52, 0.93), p = 0.013; TNBC: 16.6 vs 14.1 months, hazard ratio (95% CI): 0.72 (0.52, 1.00), p = 0.052; gBRCA1: 14.2 vs 12.6 months, hazard ratio (95% CI): 0.75 (0.55, 1.03), p = 0.073; gBRCA2: 14.6 vs 12.6 months, hazard ratio (95% CI): 0.69 (0.50, 0.95); p = 0.021). Benefit was durable, with improved PFS rates at 2 years (HR+, 27.5% vs 15.3%; TNBC, 40.4% vs 25.0%) and 3 years (HR+, 17.5% vs 8.6%; TNBC, 35.3% vs 13.0%) in all subgroups. gBRCA status (BRCA1 vs BRCA2) did not substantially affect the carboplatin/paclitaxel ± veliparib toxicity profile.

Conclusion

Veliparib plus carboplatin/paclitaxel resulted in durable benefit in subgroups defined by HR status or by gBRCA1 versus gBRCA2 mutation. Overall, addition of veliparib to carboplatin/paclitaxel was tolerable, and there were no clinically meaningful differences in adverse events between the gBRCA1 versus gBRCA2 and HR+ versus TNBC subgroups.

Trial Registration

NCT02163694, https://clinicaltrials.gov/ct2/show/NCT02163694.

New Roles of Poly(ADP-Ribose) Polymerase Inhibitors in the Treatment of Breast Cancer

ABSTRACT

Since the proof of concept of synthetic lethality between poly(ADP-ribose) polymerase inhibition and loss of BRCA1/2 homologous recombination (HR) function in preclinical models and early phase clinical trials, poly(ADP-ribose) polymerase inhibitors (PARPi) are increasing part of standard-of-care treatment for advanced breast cancers with BRCA gene mutations. The field has also recently seen benefits for PARPi in early breast cancer in those with germline BRCA1 and BRCA2 pathogenic mutations, and signals that synthetic lethal affects may occur in tumors with deficiencies in HR caused by germline, somatic, or epigenetic dysregulation of a number of HR genes. Despite the evidence of the synthetic lethal effects of PARPi, they are not always effective in HR defective cancers, and as they become part of standard of care in breast cancer, the study of prevalence of distinct mechanisms of resistance to PARPi and cross-resistance with other DNA-damaging agents such as platinum in breast cancer will be important and may inform therapy choices.

Expanding the Use of PARP Inhibitors as Monotherapy and in Combination in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer, and is known to be associated with a poor prognosis and limited therapeutic options. Poly (ADP-ribose) polymerase inhibitors (PARPi) are targeted therapeutics that have demonstrated efficacy as monotherapy in metastatic BRCA-mutant (BRCAMUT) TNBC patients. Improved efficacy of PARPi has been demonstrated in BRCAMUT breast cancer patients who have either received fewer lines of chemotherapy or in chemotherapy-naïve patients in the metastatic, adjuvant, and neoadjuvant settings. Moreover, recent trials in smaller cohorts have identified anti-tumor activity of PARPi in TNBC patients, regardless of BRCA-mutation status. While there have been concerns regarding the efficacy and toxicity of the use of PARPi in combination with chemotherapy, these challenges can be mitigated with careful attention to PARPi dosing strategies. To better identify a patient subpopulation that will best respond to PARPi, several genomic biomarkers of homologous recombination deficiency have been tested. However, gene expression signatures associated with PARPi response can integrate different pathways in addition to homologous recombination deficiency and can be implemented in the clinic more readily. Taken together, PARPi have great potential for use in TNBC patients beyond BRCAMUT status, both as a single-agent and in combination.

Veliparib monotherapy following carboplatin/paclitaxel plus veliparib combination therapy in patients with germline BRCA-associated advanced breast cancer: results of exploratory analyses from the phase III BROCADE3 trial

BACKGROUND

In the BROCADE3 trial (NCT02163694), addition of the poly(ADP-ribose) polymerase (PARP) inhibitor, veliparib, to carboplatin/paclitaxel improved progression-free survival (PFS) (hazard ratio [HR] 0.71, 95% confidence interval 0.57-0.88; P=0.002) in patients with advanced HER2-negative, germline BRCA1/2-mutated breast cancer. A subset of patients discontinued both carboplatin and paclitaxel prior to progression and continued on veliparib/placebo maintenance monotherapy until progression. Analyses in this patient subgroup are reported.

PATIENTS AND METHODS

Patients were randomized 2:1 to veliparib plus carboplatin/paclitaxel or placebo plus carboplatin/paclitaxel. Veliparib (120 mg twice daily [BID]) or placebo was given on days -2 to 5, carboplatin (AUC 6 mg/mL) on day 1, and paclitaxel (80 mg/m²) on days 1, 8, and 15 of 21-day cycles. Patients who discontinued both carboplatin and paclitaxel prior to progression received blinded study drug monotherapy at an increased dose of 300-400 mg BID continuously. PFS was the primary endpoint. Exploratory analyses were performed in the subgroup of patients who received blinded study drug as monotherapy. A time-varying Cox model including data from all patients was also used to evaluate treatment effect in the combination and monotherapy phases.

RESULTS

136 of 337 patients randomized to veliparib plus carboplatin/paclitaxel and 58/172 patients randomized to placebo plus carboplatin/paclitaxel discontinued both carboplatin and paclitaxel prior to progression and continued on blinded veliparib or placebo monotherapy. In this blinded monotherapy subgroup, investigator-assessed median PFS from randomization was 25.7 months with veliparib versus 14.6 months with placebo. HRs from a time-varying Cox model favored veliparib during both combination therapy and monotherapy. Any-grade adverse events (AEs) occurring in the monotherapy phase were primarily gastrointestinal. The most common grade ≥3 AEs were neutropenia and anemia (4% each with veliparib; 5% and 2%, respectively, with placebo).

CONCLUSIONS

Veliparib maintenance monotherapy had a tolerable safety profile and may extend PFS following combination chemotherapy.