Exploring and comparing adverse events between PARP inhibitors

Preclinical Assessment of the Combination of PSMA-Targeting Radionuclide Therapy with PARP Inhibitors for Prostate Cancer Treatment

Prostate specific membrane antigen targeted radionuclide therapy (PSMA-TRT) is a promising novel treatment for prostate cancer (PCa) patients. However, PSMA-TRT cannot be used for curative intent yet, thus additional research on how to improve the therapeutic efficacy is warranted. A potential way of achieving this, is combining TRT with poly ADP-ribosylation inhibitors (PARPi), which has shown promising results for TRT of neuroendocrine tumor cells. Currently, several clinical trials have been initiated for this combination for PCa, however so far, no evidence of synergism is available for PCa. Therefore, we evaluated the combination of PSMA-TRT with three classes of PARPi in preclinical PCa models. In vitro viability and survival assays were performed using PSMA-expressing PCa cell lines PC3-PIP and LNCaP to assess the effect of increasing concentrations of PARPi veliparib, olaparib or talazoparib in combination with PSMA-TRT compared to single PARPi treatment. Next, DNA damage analyses were performed by quantifying the number of DNA breaks by immunofluorescent stainings. Lastly, the potential of the combination treatments was studied in vivo in mice bearing PC3-PIP xenografts. Our results show that combining PSMA-TRT with PARPi did not synergistically affect the in vitro clonogenic survival or cell viability. DNA-damage analysis revealed only a significant increase in DNA breaks when combining PSMA-TRT with veliparib and not in the other combination treatments. Moreover, PSMA-TRT with PARPi treatment did not improve tumor control compared to PSMA-TRT monotherapy. Overall, the data presented do not support the assumption that combining PSMA-TRT with PARPi leads to a synergistic antitumor effect in PCa. These results underline that extensive preclinical research using various PCa models is imperative to validate the applicability of the combination strategy for PCa, as it is for other cancer types.

A Novel PARP Inhibitor YHP-836 For the Treatment of BRCA-Deficiency Cancers

PARP inhibitors have clinically demonstrated good antitumor activity in patients with BRCA mutations. Here, we described YHP-836, a novel PARP inhibitor, YHP-836 demonstrated excellent inhibitory activity for both PARP1 and PARP2 enzymes. It also allosterically regulated PARP1 and PARP2 via DNA trapping. YHP-836 showed cytotoxicity in tumor cell lines with BRCA mutations and induced cell cycle arrest in the G2/M phase. YHP-836 also sensitized tumor cells to chemotherapy agents in vitro. Oral administration of YHP-836 elicited remarkable antitumor activity either as a single agent or in combination with chemotherapy agents in vivo. These results indicated that YHP-836 is a well-defined PARP inhibitor.

A Pan-Canadian Consensus Statement on First-Line PARP Inhibitor Maintenance for Advanced, High-Grade Serous and Endometrioid Tubal, Ovarian, and Primary Peritoneal Cancers

The majority of patients with advanced, high-grade epithelial-tubo ovarian cancer (EOC) respond well to initial treatment with platinum-based chemotherapy; however, up to 80% of patients will experience a recurrence. Poly(ADP-ribose) Polymerase (PARP) inhibitors have been established as a standard of care maintenance therapy to prolong remission and prevent relapse following a response to first-line platinum-chemotherapy. Olaparib and niraparib are the PARP inhibitors currently approved for use in the first-line maintenance setting in Canada. Selection of maintenance therapy requires consideration of patient and tumour factors, presence of germline and somatic mutations, expected drug toxicity profile, and treatment access. This paper discusses the current clinical evidence for first-line PARP inhibitor maintenance therapy in patients with advanced, high-grade EOC and presents consensus statements and a treatment algorithm to aid Canadian oncologists on the selection and use of PARP inhibitors within the Canadian EOC treatment landscape.

Myelodysplastic Syndrome/Acute Myeloid Leukemia Following the Use of Poly-ADP Ribose Polymerase (PARP) Inhibitors: A Real-World Analysis of Postmarketing Surveillance Data

Background and purpose: poly-ADP ribose polymerase (PARP) inhibitors show impressive efficacy in a range of tumors. However, concerns about rare and fatal adverse events, including myelodysplastic syndrome (MDS) and acute myelogenous leukemia (AML) have arisen. The aim of this study was to excavate and evaluate the risk of PARP inhibitors causing MDS and AML based on real-world data from two international pharmacovigilance databases.

Methods: We analyzed adverse event (AE) reports of four PARP inhibitors (olaparib, niraparib, rucaparib and talazoparib) associated with MDS and AML from the United States Food and Drug Administration (FDA) Adverse Event Reporting System (FAERS) and EudraVigilance (EV) databases between 1 October 2014, and 30 September 2021, including demographic characteristics, fatality and times to onset. Three different data mining algorithms were used to detect the signals of PARP inhibitors associated with MDS and AML.

Results: In total, 16,710 and 11,937 PARP inhibitor AE reports were found in the FAERS and EV databases, of which 332 and 349 were associated with MDS and AML, respectively. The median latencies of MDS and AML associated with PARP inhibitors were 211 [interquartile range (IQR) 93.5–491.25] days and 355 (IQR 72.00–483.50) days, respectively. The average fatality rates of MDS and AML caused by the four PARP inhibitors were 39.23 and 45.39%, respectively, in the FAERS database, while those in the EV database were 32.32 and 34.94%, respectively. Based on the criteria used for the three algorithms, a significant disproportionate association was found between PARP inhibitors as a drug class and MDS/AML. Notably, the risk of MDS was much higher than that of AML. Olaparib appeared to have a stronger association with MDS and AML than did other PARP inhibitors.

Conclusion: In the real world, PARP inhibitors increase the risk of MDS and AML, which can result in high mortality and tend to occur during long-term use. Our findings provide objective evidence for the postmarketing safety of PARP inhibitors.

Cost comparison of adverse event management among breast and ovarian cancer patients treated with poly (ADP-ribose) polymerase inhibitors: analysis based on phase 3 clinical trials

BACKGROUND

The economic impact of adverse events (AEs) for poly (ADP-ribose) polymerase inhibitors (PARPis) in ovarian or breast cancer has not been widely evaluated.

OBJECTIVE

Compare PARPi-related AE management costs from a US payer perspective.

METHODS

The frequency of treatment-related grade 3-4 AEs was obtained from published clinical trials of PARPis for the treatment of advanced ovarian cancer (AOC), platinum-sensitive recurrent ovarian cancer (PSROC), and metastatic breast cancer (MBC). AE management costs per patient (2020 USD) per treatment course were calculated by multiplying the AE unit costs by the frequency of AEs for each arm of each trial. Sensitivity analyses were conducted according to the lower and upper limits of the 95% confidence interval for AE rates and unit costs, respectively. Scenarios were also performed to explore the uncertainty of outcomes.

RESULTS

Total AE management costs in AOC were: $3,904, olaparib; $5,595, olaparib plus bevacizumab; and $12,215, niraparib. In PSROC, total costs were: $3,894, olaparib; $6,001, rucaparib; and $11,492, niraparib, and in MBC: $3,574, olaparib; and $9,489, talazoparib. Hematological toxicities were the key drivers of AE management costs for PARPis.

CONCLUSIONS

The main AEs among PARPis were hematological. Olaparib was associated with lower AE costs compared to other PARPis.

Radioresistance of Non-Small Cell Lung Cancers and Therapeutic Perspectives

Survival in unresectable locally advanced stage non-small cell lung cancer (NSCLC) patients remains poor despite chemoradiotherapy. Recently, adjuvant immunotherapy improved survival for these patients but we are still far from curing most of the patients with only a 57% survival remaining at 3 years. This poor survival is due to the resistance to chemoradiotherapy, local relapses, and distant relapses. Several biological mechanisms have been found to be involved in the chemoradioresistance such as cancer stem cells, cancer mutation status, or the immune system. New drugs to overcome this radioresistance in NSCLCs have been investigated such as radiosensitizer treatments or immunotherapies. Different modalities of radiotherapy have also been investigated to improve efficacity such as dose escalation or proton irradiations. In this review, we focused on biological mechanisms such as the cancer stem cells, the cancer mutations, the antitumor immune response in the first part, then we explored some strategies to overcome this radioresistance in stage III NSCLCs with new drugs or radiotherapy modalities.

Olaparib Maintenance Monotherapy in Asian Patients with Platinum-Sensitive Relapsed Ovarian Cancer: Phase III Trial (L-MOCA)

PURPOSE

In patients with platinum-sensitive relapsed (PSR) ovarian cancer, olaparib maintenance monotherapy significantly improves progression-free survival (PFS) versus placebo. However, evidence in the Asian population is lacking. This is the first study to evaluate olaparib efficacy and tolerability exclusively in Asian patients with PSR ovarian cancer.

PATIENTS AND METHODS

Considering the limited placebo effect and significant clinical benefit of olaparib in previous trials, and the rapid approval of olaparib in China, this phase III study was designed as an open-label, single-arm trial. Patients with high-grade epithelial PSR ovarian cancer were enrolled from country-wide clinical centers across China and Malaysia. Patients received oral olaparib (300 mg) twice daily until disease progression or unacceptable toxicity. Primary endpoint was median PFS (mPFS). Primary analysis of PFS using the Kaplan-Meier method was performed when data reached 60% maturity (clinicaltrials.gov NCT03534453).

RESULTS

Between 2018 and 2020, 225 patients were enrolled, and 224 received olaparib; 35.7% had received ≥3 lines of chemotherapy, 35.3% had achieved complete response to their last line of platinum-based chemotherapy, and 41.1% had a platinum-free interval ≤12 months. At primary data cut-off (December 25, 2020), overall mPFS was 16.1 months; mPFS was 21.2 and 11.0 months in BRCA-mutated and wild-type BRCA subgroups, respectively. Adverse events (AE) occurred in 99.1% of patients (grade ≥3, 48.7%); 9.4% discontinued therapy due to treatment-related AEs.

CONCLUSIONS

Olaparib maintenance therapy was highly effective and well tolerated in Asian patients with PSR ovarian cancer, regardless of BRCA status. This study highlights the promising efficacy of olaparib in this Asian population. See related commentary by Nicum and Blagden, p. 2201.

Using GPCRs as Molecular Beacons to Target Ovarian Cancer with Nanomedicines

The five-year survival rate for women with ovarian cancer is very poor despite radical cytoreductive surgery and chemotherapy. Although most patients initially respond to platinum-based chemotherapy, the majority experience recurrence and ultimately develop chemoresistance, resulting in fatal outcomes. The current administration of cytotoxic compounds is hampered by dose-limiting severe adverse effects. There is an unmet clinical need for targeted drug delivery systems that transport chemotherapeutics selectively to tumor cells while minimizing off-target toxicity. G protein-coupled receptors (GPCRs) are the largest family of membrane receptors, and many are overexpressed in solid tumors, including ovarian cancer. This review summarizes the progress in engineered nanoparticle research for drug delivery for ovarian cancer and discusses the potential use of GPCRs as molecular entry points to deliver anti-cancer compounds into ovarian cancer cells. A newly emerging treatment paradigm could be the personalized design of nanomedicines on a case-by-case basis.

Joining the PARty: PARP Regulation of KDM5A during DNA Repair (and Transcription?)

The lysine demethylase KDM5A collaborates with PARP1 and the histone variant macroH2A1.2 to modulate chromatin to promote DNA repair. Indeed, KDM5A engages poly(ADP-ribose) (PAR) chains at damage sites through a previously uncharacterized coiled-coil domain, a novel binding mode for PAR interactions. While KDM5A is a well-known transcriptional regulator, its function in DNA repair is only now emerging. Here we review the molecular mechanisms that regulate this PARP1-macroH2A1.2-KDM5A axis in DNA damage and consider the potential involvement of this pathway in transcription regulation and cancer. Using KDM5A as an example, we discuss how multifunctional chromatin proteins transition between several DNA-based processes, which must be coordinated to protect the integrity of the genome and epigenome. The dysregulation of chromatin and loss of genome integrity that is prevalent in human diseases including cancer may be related and could provide opportunities to target multitasking proteins with these pathways as therapeutic strategies.

GCIG-Consensus guideline for Long-term survivorship in gynecologic Cancer: A position paper from the gynecologic cancer Intergroup (GCIG) symptom benefit committee

INTRODUCTION

Long-term survivors of gynecological cancers may be cured but still have ongoing health concerns and long-term side effects following cancer treatment. The aim of this brainstorming meeting was to develop recommendations for long-term follow-up for survivors from gynecologic cancer.

METHODS

International experts, representing each member group within the Gynecologic Cancer InterGroup (GCIG), met to define long-term survival, propose guidelines for long term follow-up and propose ways to implement long term survivorship follow-up in clinical trials involving gynecological cancers.

RESULTS

Long-term survival with/from gynecological cancers was defined as survival of at least five years from diagnosis, irrespective of disease recurrences. Review of the literature showed that more than 50% of cancer survivors with gynecological cancer still experienced health concerns/long-term side effects. Main side effects included neurologic symptoms, sleep disturbance, fatigue, sexual dysfunction, bowel and urinary problems and lymphedema. In this article, long-term side effects are discussed in detail and treatment options are proposed. Screening for second primary cancers and lifestyle counselling (nutrition, physical activity, mental health) may improve quality of life and overall health status, as well as prevent cardiovascular events. Clinical trials should address cancer survivorship and report patient reported outcome measures (PROMs) for cancer survivors.

CONCLUSION

Long-term survivors after gynecological cancer have unique longer term challenges that need to be addressed systematically by care givers. Follow-up after completing treatment for primary gynecological cancer should be offered lifelong. Survivorship care plans may help to summarize cancer history, long-term side effects and to give information on health promotion and prevention.

A phase 1 and pharmacodynamic study of chronically-dosed, single-agent veliparib (ABT-888) in patients with BRCA1- or BRCA2-mutated cancer or platinum-refractory ovarian or triple-negative breast cancer

PURPOSE

BRCA1 or BRCA2 mutated cancers (BRCAmut) have intrinsic sensitivity to PARP inhibitors due to deficiency in homologous recombination-mediated DNA repair. There are similarities between BRCAmut and BRCAwt ovarian and basal-like breast cancers. This phase I study determined the recommended phase II dose (RP2D) and preliminary efficacy of the PARP inhibitor, veliparib (ABT-888), in these patients.

PATIENTS AND METHODS

Patients (n = 98) were dosed with veliparib 50-500 mg twice daily (BID). The BRCAmut cohort (n = 70) contained predominantly ovarian (53%) and breast (23%) cancers; the BRCAwt cohort (n = 28) consisted primarily of breast cancer (86%). The MTD, DLT, adverse events, PK, PD, and clinical response were assessed.

RESULTS

DLTs were grade 3 nausea/vomiting at 400 mg BID in a BRCAmut carrier, grade 2 seizure at 400 mg BID in a patient with BRCAwt cancer, and grade 2 seizure at 500 mg BID in a BRCAmut carrier. Common toxicities included nausea (65%), fatigue (45%), and lymphopenia (38%). Grade 3/4 toxicities were rare (highest lymphopenia at 15%). Overall response rate (ORR) was 23% (95% CI 13-35%) in BRCAmut overall, and 37% (95% CI 21-55%) at 400 mg BID and above. In BRCAwt, ORR was 8% (95% CI 1-26%), and clinical benefit rate was 16% (95% CI 4-36%), reflecting prolonged stable disease in some patients. PK was linear with dose and was correlated with response and nausea.

CONCLUSIONS

Continuous veliparib is safe and tolerable. The RP2D was 400 mg BID. There is evidence of clinical activity of veliparib in patients with BRCAmut and BRCAwt cancers.

Olaparib Outcomes in Metastatic Castration-Resistant Prostate Cancer: First Real-World Experience in Safety and Efficacy from China

Background

Olaparib, a poly (ADP-ribose) polymerase (PARP) inhibitor, has been approved for use in breast cancer susceptibility gene (BRCA)-mutated metastatic castration-resistant prostate cancer (mCPRC) patients. Our aim was to evaluate the adverse events (AEs) and efficacy of Olaparib in the treatment of mCRPC patients from the Chinese mainland.

Methods

We retrospectively included mCPRC patients treated with Olaparib more than for 28 days. Patients with alterations in 15 homologous recombination repair (HRR) genes were defined as the HRRmt group, and the rest were defined as the HRRwt group. The efficacy was analyzed by prostate-specific antigen (PSA) decreased rate and PSA progression-free survival (PFS). The partial response, good response, and high response of PSA were defined as a reduction of between 0% and 50%, greater than 50%, and greater than 90% from baseline.

Results

A total of 43 patients were enrolled in this study, including 26 HRRmt group patients and 17 HRRwt group patients. Two HRRwt patients received additional abiraterone therapy. A partial response, good response, and high response were achieved in 89% (23/26), 59% (15/26), and 15% (4/26) of HRRmt group patients, respectively. In HRRwt group, 59% (10/17), 35% (6/17), and 12% (2/17) of patients met the criteria of partial response, good response, and high response, respectively. Median PFS was 8.0 months in the HRRmt group and 3.0s months in the HRRwt group (HR, 0.61; 95% CI, 0.24–1.14; p = 0.148), respectively. All the 20 patients had AEs during Olaparib treatment. Ten episodes of grade 3 or 4 AEs were observed in four patients. The most common all-grade AEs were fatigue or asthenia (70%), anemia (65%), and decreased appetite (55%).

Conclusions

Most of the AEs were tolerated, and Olaparib was effective in mCRPC patients with HRR deficiency. In addition, the underlying mechanism of the efficacy of Olaparib observed in HRRwt group patients remained explored.

Nephrotoxicity in cancer treatment: An update

It has been estimated that nearly 80% of anticancer drug-treated patients receive potentially nephrotoxic drugs, while the kidneys play a central role in the excretion of anticancer drugs. Nephrotoxicity has long been a serious complication that hampers the effectiveness of cancer treatment and continues to influence both mortality and length of hospitalization among cancer patients exposed to either conventional cytotoxic agents or targeted therapies. Kidney injury arising from anticancer drugs tends to be associated with preexisting comorbidities, advanced cancer stage, and the use of concomitant non-chemotherapeutic nephrotoxic drugs. Despite the prevalence and impact of kidney injury on therapeutic outcomes, the field is sorely lacking in an understanding of the mechanisms driving cancer drug-induced renal pathophysiology, resulting in quite limited and largely ineffective management of anticancer drug-induced nephrotoxicity. Consequently, there is a clear imperative for understanding the basis for nephrotoxic manifestations of anticancer agents for the successful management of kidney injury by these drugs. This article provides an overview of current preclinical research on the nephrotoxicity of cancer treatments and highlights prospective approaches to mitigate cancer therapy-related renal toxicity.

Appropriate Selection of PARP Inhibitors in Ovarian Cancer

OPINION STATEMENT

Poly-ADP-ribose polymerase inhibitors (PARPi) are a class of anti-cancer drugs that target DNA repair pathways and have shown promising efficacy in patients with ovarian cancer in recent clinical trials. To date, there have been 9 FDA PARPi approvals/indications in ovarian cancer since 2014, highlighting the importance of this class of agents in the treatment of ovarian cancer. BRCA1/2-mutated tumors or other forms of homologous recombination deficient (HRD) tumors are particularly susceptible to PARP inhibition and have seen the greatest benefits of improvement in response rate and progression-free survival (PFS) in clinical trials. Patients with homologous recombination-proficient tumors also receive benefit, especially when a nice response to paltinum is noted, but to a lesser extent. PARP inhibitors now have FDA approval and indications in first-line and recurrent maintenance, and treatment. PARP inhibitor use as maintenance therapy in the front-line setting is now considered the standard of care in patients with BRCA1/2 mutations based on the SOLO-1/GOG-3004/ENGOT study. PARP inhibitors are also recommended per ASCO guidelines in all patients with ovarian cancer as front-line maintenance therapy based on the PRIMA/ENGOT-OV26/GOG-3012 trial. The combination of PARP inhibitor, olaparib, and the anti-angiogenesis inhibitor bevacizumab is also approved as maintenance therapy after front-line chemotherapy treatment in patients with HRD tumors and is an option for patients who have initiated bevacizumab with their chemotherapy treatment. PARPi are also FDA approved and can be utilized as a treatment in third-line and beyond in recurrent ovarian cancer patients with BRCA1/2 mutations and HRD tumors. In this review, we will cover in detail when PARP inhibitor use is appropriate in ovarian cancer, as well as the various clinical factors to take into consideration when selecting a PARP inhibitor regimen.

Involvement of Cancer Stem Cells in Chemoresistant Relapse of Epithelial Ovarian Cancer Identified by Transcriptome Analysis

Epithelial ovarian cancer (EOC) is the most lethal gynecological malignancy. Despite the initial resection and chemotherapeutic treatment, relapse is common, which leads to poor survival rates in patients. A primary cause of recurrence is the persistence of ovarian cancer stem cells (OCSCs) with high tumorigenicity and chemoresistance. To achieve a better therapeutic response in EOC relapse, the mechanisms underlying acquired chemoresistance associated with relapse-initiating OCSCs need to be studied. Transcriptomes of both chemosensitive primary and chemoresistant relapse EOC samples were obtained from ICGC OV-AU dataset for differential expression analysis. The upregulated genes were further studied using KEGG and GO analysis. Significantly increased expression of eighteen CSC-related genes was found in chemoresistant relapse EOC groups. Upregulation of the expression in four hub genes including WNT3A, SMAD3, KLF4, and PAX6 was verified in chemoresistant relapse samples via immunohistochemistry staining, which confirmed the existence and enrichment of OCSCs in chemoresistant relapse EOC. KEGG and GO enrichment analysis in microarray expression datasets of isolated OCSCs indicated that quiescent state, increased ability of drug efflux, and enhanced response to DNA damage may have caused the chemoresistance in relapse EOC patients. These findings demonstrated a correlation between OCSCs and acquired chemoresistance and illustrated potential underlying mechanisms of OCSC-initiated relapse in EOC patients. Meanwhile, the differentially expressed genes in OCSCs may serve as novel preventive or therapeutic targets against EOC recurrence in the future.

Adverse Event Profiles of PARP Inhibitors: Analysis of Spontaneous Reports Submitted to FAERS

Background: Several poly ADP ribose polymerase inhibitors (PARPis) are currently approved for the treatment of a variety of cancers. The safety profile of PARPis has not yet been systemically analyzed in the real world. We conducted this pharmacovigilance analysis using the US FDA's Adverse Event Reporting System (FAERS) database to explore the difference in adverse events (AEs) among PARPis. Methods: FAERS data (December 2014 to October 2021) were searched for reports of all FDA-approved PARPis across all indications. We used the standardized MedDRA query (SMQ) generalized search AEs on the preferred term (PT) level based on case reports. After filtering duplicate reports, disproportionality analysis was used to detect safety signals by calculating reporting odds ratios (ROR). Reports were considered statistically significant if the 95% confidence interval did not contain the null value. Results: Within the standardized MedDRA queries, significant safety signals were found, including those for olaparib [blood premalignant disorders (ROR = 17.06)], rucaparib [taste and smell disorders (ROR = 9.17)], niraparib [hematopoietic throbocytopenia (ROR = 28.2)], and talazoparib [hematopoietic erythropenia (ROR = 9.38)]. For AEs on the PT level, we found several significant signals, including platelet count decreased with niraparib (ROR = 52.78); red blood cell count decreased with niraparib (ROR = 70.47) and rucaparib (ROR = 15.09); myelodysplastic syndrome with olaparib (ROR = 35.47); acute myeloid leukaemia with olaparib (ROR = 25.14); blood pressure fluctuation with niraparib (ROR = 20.54); lymphangioleiomyomatosis with niraparib (ROR = 471.20); photosensitivity reaction with niraparib (ROR = 21.77) and rucaparib (ROR = 18.92); renal impairment with rucaparib (ROR = 33.32); and interstitial lung disease with Olaparib (ROR = 11.31). All the detected safety signals were confirmed using signals of disproportionality reporting methods. Conclusion: PARPis differed in their safety profile reports. The analysis of the FAERS database revealed significant safety signals that matched previously published case reports, including serious gastrointestinal, blood and lymphatic system, cardiovascular and respiratory complications, which require individualized drug administration according to patients' conditions.

Targeting key proteins involved in transcriptional regulation for cancer therapy: Current strategies and future prospective

The key proteins involved in transcriptional regulation play convergent roles in cellular homeostasis, and their dysfunction mediates aberrant gene expressions that underline the hallmarks of tumorigenesis. As tumor progression is dependent on such abnormal regulation of transcription, it is important to discover novel chemical entities as antitumor drugs that target key tumor-associated proteins involved in transcriptional regulation. Despite most key proteins (especially transcription factors) involved in transcriptional regulation are historically recognized as undruggable targets, multiple targeting approaches at diverse levels of transcriptional regulation, such as epigenetic intervention, inhibition of DNA-binding of transcriptional factors, and inhibition of the protein-protein interactions (PPIs), have been established in preclinically or clinically studies. In addition, several new approaches have recently been described, such as targeting proteasomal degradation and eliciting synthetic lethality. This review will emphasize on accentuating these developing therapeutic approaches and provide a thorough conspectus of the drug development to target key proteins involved in transcriptional regulation and their impact on future oncotherapy.

Targeting DNA Damage Response and Immune Checkpoint for Anticancer Therapy

Deficiency in DNA damage response (DDR) genes leads to impaired DNA repair functions that will induce genomic instability and facilitate cancer development. However, alterations of DDR genes can serve as biomarkers for the selection of suitable patients to receive specific therapeutics, such as immune checkpoint blockade (ICB) therapy. In addition, certain altered DDR genes can be ideal therapeutic targets through adapting the mechanism of synthetic lethality. Recent studies indicate that targeting DDR can improve cancer immunotherapy by modulating the immune response mediated by cGAS-STING-interferon signaling. Investigations of the interplay of DDR-targeting and ICB therapies provide more effective treatment options for cancer patients. This review introduces the mechanisms of DDR and discusses their crucial roles in cancer therapy based on the concepts of synthetic lethality and ICB. The contemporary clinical trials of DDR-targeting and ICB therapies in breast, colorectal, and pancreatic cancers are included.

PARP Inhibitors Resistance: Mechanisms and Perspectives

PolyADP-ribose polymerase (PARP) inhibitors (PARPis) represent the first clinically approved drugs able to provoke "synthetic lethality" in patients with homologous recombination-deficient (HRD) tumors. Four PARPis have just received approval for the treatment of several types of cancer. Besides, another three additional PARPis underlying the same mechanism of action are currently under investigation. Despite the success of these targeted agents, the increasing use of PARPis in clinical practice for the treatment of different tumors raised the issue of PARPis resistance, and the consequent disease relapse and dismal prognosis for patients. Several mechanisms of resistance have been investigated, and ongoing studies are currently focusing on strategies to address this challenge and overcome PARPis resistance. This review aims to analyze the mechanisms underlying PARPis resistance known today and discuss potential therapeutic strategies to overcome these processes of resistance in the future.

cGAS/STING cross-talks with cell cycle and potentiates cancer immunotherapy

The correct duplication and transfer of genetic material to daughter cells is the major event of cell division. Dysfunction of DNA replication or chromosome segregation presents challenges in cancer initiation and development as well as opportunities for cancer treatment. Cyclic GMP-AMP synthase (cGAS) of the innate immune system detects cytoplasmic DNA and mediates downstream immune responses through the molecule stimulator of interferon genes (STING). However, how cytosolic DNA sensor cGAS participates in guaranteeing accurate cell division and preventing tumorigenesis is still unclear. Recent evidence indicates malfunction of cGAS/STING pathway in cancer progression. Cell cycle-targeted therapy synergizes with immunotherapy via cGAS/STING activation, leading to promising therapeutic benefit. Here, we review the interactions between cell cycle regulation and cGAS/STING signaling, thus enabling us to understand the role of cGAS/STING in cancer initiation, development, and treatment.

Intervention of 3-aminobenzamide against Dextran Sulphate Sodium induced colitis in mice: Investigations on molecular mechanisms

Various preclinical and clinical studies reported that Poly [ADP-ribose] polymerase 1 plays significant role in all acute and chronic inflammatory diseases with different etiopathogenesis. The present study aims to investigate the protective effect of 3-aminobenzamide in Dextran Sulphate Sodium induced ulcerative colitis and associated molecular mechanisms. Ulcerative colitis in male BALB/c mice was induced using Dextran sulphate sodium (3 %w/v) for 3 cycles with 7 days recovery period in-between. 3-aminobenzamide was administered at the doses of 5, 10 and 20 mg/kg starting from the I^st week of remission period and was continued till the termination of the experiment. The effect of 3-aminbenzamide was evaluated using biochemical parameters, histopathological evaluations, ELISA, immunohistochemistry, immunofluorescence and Western blot analysis. All the doses of 3-aminobenzamide (5 mg/kg; 10 mg/kg and 20 mg/kg) ameliorated the severity of ulcerative colitis by modulating various molecular targets such as poly[ADP-ribose] polymerase 1, nuclear factor kappa-light-chain-enhancer of activated B cells, NLR family pyrin domain containing 3, apoptosis-associated speck-like protein containing a caspase-recruitment domain, cysteine aspartases, interleukin-1β, proliferating cell nuclear antigen, sirtuin 1, adenosine monophosphate-activated protein kinase, tumour necrosis factor-α and catalase. However, the lower doses (5 and 10 mg/kg) exerted more prominent effects in comparison to the high dose (20 mg/kg). Further, 3-aminobenzamide treatment restored the intestinal integrity by increasing the expression of occludin and significantly ameliorated ulcerative colitis associated elevated lipopolysaccharides, oxidative and nitrosative stress, cellular damage and apoptosis. Lower doses of 3-aminobenzamide showed more prominent protective effects against ulcerative colitis associated damage as compared to higher dose.

Dual-target inhibitors of poly (ADP-ribose) polymerase-1 for cancer therapy: Advances, challenges, and opportunities

PARP1 plays a crucial role in DNA damage repair, making it an essential target for cancer therapy. PARP1 inhibitors are widely used to treat BRCA-deficient malignancies, and six PARP inhibitors have been approved for clinical use. However, excluding the great clinical success of PARP inhibitors, the concomitant toxicity, drug resistance, and limited scope of application restrict their clinical efficacy. To find solutions to these problems, dual-target inhibitors have shown great potential. In recent years, several studies have linked PAPR1 to other primary cancer targets. Many dual-target inhibitors have been developed using structural fusion, linkage, or library construction methods, overcoming the defects of many single-target inhibitors of PARP1 and achieving great success in clinical cancer therapy. This review summarizes the advance of dual-target PARP1 inhibitors in recent years, focusing on their structural optimization process, structure-activity relationships (SARs), and in vitro or in vivo analysis results.

Ovarian cancer and KiSS-1 gene expression: A consideration of the use of Kisspeptin plus Kisspeptin aptamers in diagnostics and therapy

Gynaecological cancers continue to present a significant health burden upon the health of the global female population. This deficit is most prominent with ovarian cancer which possesses the lowest survival rate compared to all other cancers occurring within this anatomical region, with an annual UK-mortality of 7,300. The poor tolerability and selectively of the treatment options that are currently available is likely to have contributed to this high mortality rate thus, demonstrating the need for the development of enhanced therapeutic approaches. Aptamer technology would involve the engineering of specifically sequenced oligonucleotide chains, which bind to macromolecular targets with a high degree of affinity and selectively. Recent in-vitro studies conducted upon the clinical utility of this technique have supported its superiority in targeting individual therapeutic drug targets compared to various other targeting moieties currently within therapeutic use such as, monoclonal antibodies. For this reason, the employment of this technique is likely to be favourable in reducing the incidence of non-specific, chemotherapy-associated adverse effects. Kisspeptin is a naturally expressed polypeptide with an established role in the development of the reproductive system and other proposed roles in influencing the ability of ovarian cancer growths to exhibit the metastasis hallmark. This distinctive feature would indicate the potential for the manipulation of this pathway through the application of aptamer structures in developing a novel prophylactic strategy and improve the long-term outcome for ovarian cancer patients.

Everything Comes with a Price: The Toxicity Profile of DNA-Damage Response Targeting Agents

Simple Summary

DNA damage induces genome instability, which may elicit cancer development. Defects in the DNA repair machinery further enhance cancer predisposition, but can also be exploited as a therapeutic target. Indeed, targeted agents against specific components of DNA repair, such as PARP inhibitors, are employed in various tumor types, while others, such as ATR, CHK1 or WEE1 inhibitors, are in clinical development. Even though these molecules have proven to be effective in different settings, they display several on- and off-target toxicities, shared by the whole pharmacological class or are drug specific. Among these effects, hematological and gastrointestinal toxicities are the most common, while others are less frequent but potentially life-threatening (e.g., myelodysplastic syndromes). Particular caution is needed in the case of combinatorial therapeutic approaches, which are currently being developed in clinical trials. In any case, it is necessary to recognize and properly manage adverse events of these drugs. This review provides a comprehensive overview on the safety profile of DDR-targeting agents, including indications for their management in clinical practice.

Abstract

Targeting the inherent vulnerability of cancer cells with an impaired DNA Damage Repair (DDR) machinery, Poly-ADP-Ribose-Polymerase (PARP) inhibitors have yielded significant results in several tumor types, eventually entering clinical practice for the treatment of ovarian, breast, pancreatic and prostate cancer. More recently, inhibitors of other key components of DNA repair, such as ATR, CHK1 and WEE1, have been developed and are currently under investigation in clinical trials. The inhibition of DDR inevitably induces on-target and off-target adverse events. Hematological and gastrointestinal toxicities as well as fatigue are common with all DDR-targeting agents, while other adverse events are drug specific, such as hypertension with niraparib and transaminase elevation with rucaparib. Cases of pneumonitis and secondary hematological malignancies have been reported with PARP inhibitors and, despite being overly rare, they deserve particular attention due to their severity. Safety also represents a crucial issue for the development of combination regimens incorporating DDR-targeting agents with other treatments, such as chemotherapy, anti-angiogenics or immunotherapy. As such, overlapping and cumulative toxicities should be considered, especially when more than two classes of drugs are combined. Here, we review the safety profile of DDR-targeting agents when used as single agents or in combination and we provide principles of toxicity management.

Randomized CLIO/BGOG-ov10 trial of olaparib monotherapy versus physician's choice chemotherapy in relapsed ovarian cancer

OBJECTIVE

Comparison of olaparib (OLA) monotherapy versus chemotherapy in patients with platinum-sensitive (PSOC) or platinum-resistant ovarian cancer (PROC).

METHODS

Patients with measurable disease and ≥ 1 prior line of chemotherapy (CT) were randomized 2:1 to OLA (300 mg tablets, BID) or physician's choice CT.: for PSOC: Carboplatin-Pegylated-Liposomal-Doxorubicin (PLD) or Carboplatin-Gemcitabine; for PROC: PLD, Topotecan, Paclitaxel or Gemcitabine.

RESULTS

160 patients (60 with PSOC and 100 with PROC) were randomized 2:1 to OLA (n = 107) or CT (n = 53). Baseline characteristics were similar between both arms. Overall objective response rate (ORR) for OLA and CT were similar (24.3% (26/107) and 28.3% (15/53), respectively). Clinical benefit rate (≥ 12 weeks) was similar with 54.2% (58/107) and 56.6% (30/53), respectively. In PSOC, ORR was 35.0% (14/40) and 65.0% (13/20) for OLA and CT (p = 0.053); in PROC, ORR was 17.9% (12/67) and 6.1% (2/33) for OLA and CT (p = 0.134). ORR in heavily pretreated PROC (>4 prior lines) was 22.9% (8/35) with OLA versus 0% (0/14) for CT. ORR of 35.7% (5/14) and 13.2% (7/53) was observed in BRCA-mutated and -wildtype PROC cases, respectively. Median PFS in PROC was not significantly different with 2.9 months (95% CI 2.8-5.1 in the OLA group versus 3.8 months (95% CI 3.0-6.4) in the CT group (hazard ratio [HR] 1.11 [95% CI 0.72-1.78]; log-rank p = 0.600).

CONCLUSION

OLA monotherapy showed overall an equal response rate in relapsed ovarian cancer compared with CT. In PROC, ORR and TFST tended to be higher with OLA than with CT. In heavily pretreated patients (four lines or more) with PROC disease, OLA treatment seemed to be more effective than CT.

Proteomic Analysis Reveals Low-Dose PARP Inhibitor-Induced Differential Protein Expression in BRCA1-Mutated High-Grade Serous Ovarian Cancer Cells

High-grade serous ovarian cancer (HGSOC) is the most common form of ovarian cancer diagnosed in patients worldwide. Patients with BRCA1/2-mutated HGSOC have benefited from targeted treatments such as poly(ADP-ribose) polymerase inhibitors (PARPi). Despite the initial success of PARPi-based ovarian cancer treatment regimens, approximately 70% of patients with ovarian cancer relapse and the 5-year survival rate remains at 30%. PARPi exhibit variable treatment efficacy and toxicity profiles. Furthermore, the off-target effects of PARP inhibition have not yet been fully elucidated, warranting further study of these classes of molecules in the context of HGSOC treatment. Highly reproducible quantitative mass spectrometry-based proteomic workflows have been developed for the analysis of tumor tissues and cell lines. To detect the off-target effects of PARP inhibition, we conducted a quantitative mass spectrometry-based proteomic analysis of a BRCA1-mutated HGSOC cell line treated with low doses of two PARPi, niraparib and rucaparib. Our goal was to identify PARPi-induced protein signaling pathway alterations toward a more comprehensive elucidation of the mechanism of action of PARPi beyond the DNA damage response pathway. A significant enrichment of nuclear and nucleoplasm proteins that are involved in protein binding was observed in the rucaparib-treated cells. Shared upregulated proteins between niraparib and rucaparib treatment demonstrated RNA II pol promoter-associated pathway enrichment in transcription regulation. Pathway enrichment analyses also revealed off-target effects in the Golgi apparatus and the ER. The results from our mass spectrometry-based proteomic analysis highlights notable off-target effects produced by low-dose treatment of BRCA1-mutated HGSOC cells treated with rucaparib or niraparib.

Cutaneous toxicities from targeted therapies used in oncology: Literature review of clinical presentation and management

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Cutaneous toxicities are frequent with targeted therapies.

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Managing cutaneous toxicities is critical for life-saving treatment continuation.

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Dermatologists can provide a key input in preventing and managing these toxicities.

With the development of molecular targeted therapies, a wide array of dermatologic toxicities is appearing. Their prevention, recognition, and management by dermatologists is critical to ensure antineoplastic treatment continuation. The objective of this study was to provide a literature review of the most common dermatologic toxicities due to targeted therapies in oncologic patients, including their clinical presentation, prevention, and management.

Safety Profile of Niraparib as Maintenance Therapy for Ovarian Cancer: A Systematic Review and Meta-Analysis

Background: Patients with epithelial ovarian cancer (EOC), treated with niraparib maintenance, present with haematological and gastrointestinal toxicities. Limited data exist on niraparib safety assessment. Objective: To evaluate niraparib safety profile, as maintenance therapy, in women with platinum-sensitive EOC. Methods: PubMed and Cochrane searches were carried out up to April 2021 for randomised controlled trials (RCTs) evaluating niraparib versus placebo in EOC patients with a response to platinum-based chemotherapy. Regarding the meta-analysis, for dichotomous data, the pooled risk ratio (RR) was calculated. Results: A total of 1539 patients from three RCTs revealed that niraparib-treated patients are associated with a significantly higher risk of any grade of nausea (RR, 2.15; 95% CI, 1.86 to 2.48), fatigue (RR, 1.26; 95% CI, 1.05 to 1.52, p < 0.00001), anemia (RR, 6.86; 95% CI, 2.54 to 18.52, p = 0.0001), thrombocytopenia (RR, 7.02; 95% CI, 1.68 to 29.38, p < 0.00001), vomiting (RR, 2.51; 95% CI, 1.50 to 4.19, p = 0.0005), neutropenia (RR, 2.96; 95% CI, 1.13 to 7.73, p < 0.00001), headache (RR, 2.08; 95% CI, 1.57 to 2.74, p < 0.00001), constipation (RR, 2.10; 95% CI, 1.72 to 2.57, p < 0.00001) and insomnia (RR, 2.48; 95% CI, 1.52 to 2.89, p = 0.0003) when compared with placebo. For grade 3 or 4 adverse effects, significantly higher risk was only noted for fatigue (RR,6.25; 95% CI, 1.70 to 23.05, p = 0.006), anemia (RR, 16.23; 95% CI, 4.86 to 54.17, p < 0.00001), thrombocytopenia (RR, 35.12; 95% CI, 12.23 to 100.82, p < 0.00001) and neutropenia episodes (RR, 6.35; 95% CI, 2.08 to 19.39, p = 0.001) for those taking niraparib. Notably, incidents of adverse effects and discontinuation rates were substantially lower among patients treated with an individualised niraparib dose than those treated with the standard one. Efficacy was not reduced, and no treatment-related deaths occurred during the included trials. Conclusion: Niraparib is considered an effective and well-tolerated choice, with an improved safety profile, for the maintenance treatment of EOC patients.

The cross-talk between PARylation and SUMOylation in C/EBPβ at K134 site participates in pathological cardiac hypertrophy

Poly(ADP-ribosyl)ation (PARylation) and SUMO modification (SUMOylation) are novel post-translational modifications (PTMs) mainly induced by PARP1 and SUMO1. Growing evidence has revealed that C/EBPβ plays multiple roles in biological processes and participates in cardiovascular diseases. However, the cross-talk between C/EBPβ PARylation and SUMOylation during cardiovascular diseases is unknown. This study aims to investigate the effects of C/EBPβ PTMs on cardiac hypertrophy and its underlying mechanism. Abdominal aortic constriction (AAC) and phenylephrine (PE) were conducted to induce cardiac hypertrophy. Intramyocardial delivery of recombinant adenovirus (Ad-PARP1) was taken to induce PARP1 overexpression. In this study, we found C/EBPβ participates in PARP1-induced cardiac hypertrophy. C/EBPβ K134 residue could be both PARylated and SUMOylated individually by PARP1 and SUMO1. Moreover, the accumulation of PARylation on C/EBPβ at K134 site exhibits downregulation of C/EBPβ SUMOylation at the same site. Importantly, C/EBPβ K134 site SUMOylation could decrease C/EBPβ protein stability and participates in PARP1-induced cardiac hypertrophy. Taken together, these findings highlight the importance of the cross-talk between C/EBPβ PTMs at K134 site in determining its protein level and function, suggesting that multi-target pharmacological strategies inhibiting PARP1 and activating C/EBPβ SUMOylation would be potential for treating pathological cardiac hypertrophy.

Utilization of Poly(ADP-Ribose) Polymerase Inhibitors in Ovarian Cancer: A Retrospective Cohort Study of US Healthcare Claims Data

Introduction

We aimed to characterize real-world utilization of poly(ADP-ribose) polymerase (PARP) inhibitors (PARPi) in women with ovarian cancer (OC).

Methods

This retrospective observational study of claims data from US MarketScan^® Commercial/Medicare Supplemental databases included women with OC initiating olaparib, niraparib, or rucaparib from January 1, 2017, to May 31, 2019. Patients were observed from first outpatient prescription until at least 30 days’ follow-up. Clinical events of interest (CEIs), based on adverse reactions in PARPi prescribing information, were identified from claims using ICD-9/10 codes. Other outcomes included dose modification, persistence, adherence, healthcare resource utilization (HCRU), and cost.

Results

Overall, 303, 348, and 162 women with OC received olaparib, niraparib, and rucaparib, respectively. During follow-up, risk of any CEI was higher with niraparib versus olaparib (odds ratio 3.36 [95% confidence interval 2.00–5.65]) and niraparib versus rucaparib (2.09 [1.10–3.95]), with no significant difference between rucaparib and olaparib (1.61 [0.93–2.79]). PARPi dose decreases were observed in 21.1%, 35.1%, and 30.2% of olaparib-, niraparib-, and rucaparib-treated patients, respectively. Persistence (no treatment gaps of more than 90 days) was significantly higher (P < 0.05) with olaparib (62.2%) versus niraparib (35.9%) and rucaparib (48.7%); adherence (medication possession ratio, MPR ≥ 80%) was 80.2% versus 38.6% and 63.2%, respectively (P < 0.001). Inpatient admissions and outpatient service use were higher with niraparib and rucaparib versus olaparib, reflected in mean (± standard deviation) total medical costs (excluding pharmacy) of $5393 ± 8828 for olaparib, $7732 ± 14,054 for niraparib, and $6868 ± 7929 for rucaparib.

Conclusion

Differences between the licensed PARPi were observed in the risk of experiencing a CEI, likelihood of dose modifications, ability to receive continuous PARPi therapy, HCRU, and costs.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-021-01959-5.

Parp1 promotes sleep, which enhances DNA repair in neurons

The characteristics of the sleep drivers and the mechanisms through which sleep relieves the cellular homeostatic pressure are unclear. In flies, zebrafish, mice, and humans, DNA damage levels increase during wakefulness and decrease during sleep. Here, we show that 6 h of consolidated sleep is sufficient to reduce DNA damage in the zebrafish dorsal pallium. Induction of DNA damage by neuronal activity and mutagens triggered sleep and DNA repair. The activity of the DNA damage response (DDR) proteins Rad52 and Ku80 increased during sleep, and chromosome dynamics enhanced Rad52 activity. The activity of the DDR initiator poly(ADP-ribose) polymerase 1 (Parp1) increased following sleep deprivation. In both larva zebrafish and adult mice, Parp1 promoted sleep. Inhibition of Parp1 activity reduced sleep-dependent chromosome dynamics and repair. These results demonstrate that DNA damage is a homeostatic driver for sleep, and Parp1 pathways can sense this cellular pressure and facilitate sleep and repair activity.

Comparison of the Efficacy and Safety of PARP Inhibitors as a Monotherapy for Platinum-Sensitive Recurrent Ovarian Cancer: A Network Meta-Analysis

Background

The present COVID-19 pandemic has tended toward normality. To provide convenient, safe, and effective home treatment programs for patients with recurrent ovarian cancer (ROC), the clinical efficacy and safety of poly (ADP-ribose) polymerase inhibitor (PARPi) (including olaparib, niraparib, and rucaparib) monotherapy as a maintenance treatment for platinum-sensitive ROC were systematically evaluated.

Methods

Numerous electronic databases were systematically searched for randomized controlled trials (RCTs) of PARPi maintenance treatment for ROC that were published before June 2021. The primary endpoints were overall survival (OS) and progression-free survival (PFS), and the secondary endpoint was grade 3-4 adverse effects (AEs). After data extraction and the quality evaluation of the included studies, Bayesian network meta-analysis (NMA) was performed using R software. The ability of each treatment was ranked using the surface under the cumulative ranking (SUCRA) curve.

Results

The analysis included five studies and 1390 patients. The NMA results demonstrated that compared with the placebo, olaparib and niraparib exhibited significant benefits in the gBRCA-mutated population, and respectively reduced the risk of death by 31% (HR = 0.69, 95% CI: 0.53-0.90) and 34% (HR = 0.66, 95% CI: 0.44-0.99). Olaparib, niraparib, and rucaparib were all found to be very effective in prolonging PFS in patients with ROC. All three PARPi treatments increased the number of grade 3-4 AEs in patients with ROC as compared with the placebo.

Conclusions

Overall, olaparib and niraparib maintenance treatment can significantly prolong the OS of patients with gBRCA mutations. Furthermore, the three investigated PARPi monotherapy maintenance treatments can prolong PFS regardless of BRCA mutation status. Although the incidence of AEs in the treatment groups was found to be significantly higher than that in the placebo group, the patients in the treatment group tolerated the treatment. Home oral PARPi treatment can balance tumor treatment and pandemic prevention and control, and is the most convenient, safe, and effective home treatment method available against the background of the current COVID-19 pandemic.

Systematic Review Registration

https://inplasy.com/inplasy-2021-6-0033/.

PARP inhibitors in hereditary breast and ovarian cancer and other cancers: A review

There has been a paradigm shift in the management of cancer, with the immense progress in cancer genomics. More and more targeted therapies are becoming available by the day and personalized medicine is becoming popular with specific drugs being designed for selected subgroups of patients. One such new class of targeted drugs in the armamentarium is Poly ADP Ribose Polymerase (PARP) inhibitors (PARPi), which inhibit the enzyme PARP, thus interfering with DNA repair. This strategy utilizes a pre-existing genomic lesion in tumors with homologous recombination repair defects (including BRCA mutations), weakening tumor cells further by blocking the alternate pathway of DNA repair. In this review, we discuss in detail, the evolution, genetics, mechanism of action, mechanism of resistance, indications of use of PARP inhibitors, as well as combination with other agents and future directions.

An In-Depth Review of Niraparib in Ovarian Cancer: Mechanism of Action, Clinical Efficacy and Future Directions

Niraparib is an oral, potent, highly selective poly-ADP ribose polymerase 1 (PARP1) and PARP2 inhibitor. In most developed countries, it is approved as a maintenance treatment for epithelial ovarian, fallopian tube, or primary peritoneal cancer in patients with complete or partial response to platinum-based therapy. These approvals are based on results of randomised, double-blind, placebo-controlled trials, particularly the NOVA trial and more recently the PRIMA trial. In this comprehensive review, we delve into the scientific basis of PARP inhibition, discussing both preclinical and clinical data which have led to the current approval status of niraparib. We also discuss ongoing trials and biological rationale of combination treatments involving niraparib, with particular focus on antiangiogenic drugs, immune checkpoint inhibitors and cyclic GMP-AMP synthase stimulator of interferon genes (cGAS/STING) pathway. In addition, we reflect on potential strategies and challenges of utilising current biomarkers for treatment selection of patients to ensure maximal benefit.

Understanding and overcoming resistance to PARP inhibitors in cancer therapy

Developing novel targeted anticancer therapies is a major goal of current research. The use of poly(ADP-ribose) polymerase (PARP) inhibitors in patients with homologous recombination-deficient tumours provides one of the best examples of a targeted therapy that has been successfully translated into the clinic. The success of this approach has so far led to the approval of four different PARP inhibitors for the treatment of several types of cancers and a total of seven different compounds are currently under clinical investigation for various indications. Clinical trials have demonstrated promising response rates among patients receiving PARP inhibitors, although the majority will inevitably develop resistance. Preclinical and clinical data have revealed multiple mechanisms of resistance and current efforts are focused on developing strategies to address this challenge. In this Review, we summarize the diverse processes underlying resistance to PARP inhibitors and discuss the potential strategies that might overcome these mechanisms such as combinations with chemotherapies, targeting the acquired vulnerabilities associated with resistance to PARP inhibitors or suppressing genomic instability.

Human iPSC-derived fallopian tube organoids with BRCA1 mutation recapitulate early-stage carcinogenesis

Germline pathogenic mutations in BReast CAncer (BRCA1) genes are thought to drive normal fallopian tube epithelial (FTE) cell transformation to high-grade serous ovarian cancer. No human models capture the sequence of events for disease initiation and progression. Here, we generate induced pluripotent stem cells (iPSCs) from healthy individuals and young ovarian cancer patients with germline pathogenic BRCA1 mutations (BRCA1^mut). Following differentiation into FTE organoids, BRCA1^mut lines exhibit cellular abnormalities consistent with neoplastic transformation compared to controls. BRCA1^mut organoids show an increased production of cancer-specific proteins and survival following transplantation into mice. Organoids from women with the most aggressive ovarian cancer show the greatest pathology, indicating the potential value to predict clinical severity prior to disease onset. These human FTE organoids from BRCA1^mut carriers provide a faithful physiological in vitro model of FTE lesion generation and early carcinogenesis. This platform can be used for personalized mechanistic and drug screening studies.

Yucer et al. generate a human BRCA1 mutant iPSC-derived fallopian tube organoid model, which recapitulates BRCA1 mutant ovarian carcinogenesis in vitro and shows tumors in vivo. This model provides a biologically relevant platform to validate drugs and a basis for personalized early detection and preventative strategies for women carrying BRCA1 mutations.

NAD+ Metabolism in Cardiac Health, Aging, and Disease

Nicotinamide adenine dinucleotide (NAD⁺) is a central metabolite involved in energy and redox homeostasis as well as in DNA repair and protein deacetylation reactions. Pharmacological or genetic inhibition of NAD⁺-degrading enzymes, external supplementation of NAD⁺ precursors, and transgenic overexpression of NAD⁺-generating enzymes have wide positive effects on metabolic health and age-associated diseases. NAD⁺ pools tend to decline with normal aging, obesity, and hypertension, which are all major risk factors for cardiovascular disease, and NAD⁺ replenishment extends healthspan, avoids metabolic syndrome, and reduces blood pressure in preclinical models. In addition, experimental elevation of NAD⁺ improves atherosclerosis, ischemic, diabetic, arrhythmogenic, hypertrophic, or dilated cardiomyopathies, as well as different modalities of heart failure. Here, we critically discuss cardiomyocyte-specific circuitries of NAD⁺ metabolism, comparatively evaluate distinct NAD⁺ precursors for their preclinical efficacy, and raise outstanding questions on the optimal design of clinical trials in which NAD⁺ replenishment or supraphysiological NAD⁺ elevations are assessed for the prevention or treatment of major cardiac diseases. We surmise that patients with hitherto intractable cardiac diseases such as heart failure with preserved ejection fraction may profit from the administration of NAD⁺ precursors. The development of such NAD⁺-centered treatments will rely on technological and conceptual progress on the fine regulation of NAD⁺ metabolism.

Impact of DNA Damage Response-Targeted Therapies on the Immune Response to Tumours

The DNA damage response (DDR) maintains the stability of a genome faced with genotoxic insults (exogenous or endogenous), and aberrations of the DDR are a hallmark of cancer cells. These cancer-specific DDR defects present new therapeutic opportunities, and different compounds that inhibit key components of DDR have been approved for clinical use or are in various stages of clinical trials. Although the therapeutic rationale of these DDR-targeted agents initially focused on their action against tumour cells themselves, these agents might also impact the crosstalk between tumour cells and the immune system, which can facilitate or impede tumour progression. In this review, we summarise recent data on how DDR-targeted agents can affect the interactions between tumour cells and the components of the immune system, both by acting directly on the immune cells themselves and by altering the expression of different molecules and pathways in tumour cells that are critical for their relationship with the immune system. Obtaining an in-depth understanding of the mechanisms behind how DDR-targeted therapies affect the immune system, and their crosstalk with tumour cells, may provide invaluable clues for the rational development of new therapeutic strategies in cancer.

Phase 1A/1B dose-escalation and -expansion study to evaluate the safety, pharmacokinetics, food effects and antitumor activity of pamiparib in advanced solid tumours

BACKGROUND

Pamiparib, a PARP1/2 inhibitor, demonstrated antitumor activity in preclinical models.

METHODS

This Phase 1A/1B dose-escalation/dose-expansion study enrolled adults (≥18 years) with advanced/metastatic cancer. The dose-escalation phase evaluated the recommended Phase 2 dose (RP2D), maximum tolerated dose (MTD), and pharmacokinetics; the dose-expansion phase evaluated the antitumor activity and food effects.

RESULTS

Patients (N = 101) were enrolled in dose-escalation (n = 64) and dose-expansion (n = 37). During BID dose-escalation, dose-limiting toxicities were Grade 2 nausea (n = 1, 40 mg; n = 1, 80 mg); Grade 2 nausea and Grade 2 anorexia (n = 1, 120 mg), Grade 2 nausea, Grade 3 fatigue and Grade 3 paraesthesia (n = 1, 120 mg); MTD was 80 mg BID and RP2D was 60 mg BID. Common adverse events (AEs) were nausea (69.3%), fatigue (48.5%) and anaemia (35.6%); the most common Grade ≥3 AE was anaemia (24.8%). There was a dose-proportional increase in pamiparib exposure; no food effects on pharmacokinetics were observed. In the efficacy-evaluable population (n = 77), objective response rate (ORR) was 27.3% (95% CI, 17.7-38.6%). Median duration of response was 14.9 months (95% CI, 8.7-26.3). In the epithelial ovarian cancer (EOC)-evaluable population (n = 51), ORR was 41.2% (95% CI, 27.6-55.8%).

CONCLUSIONS

Pamiparib was tolerated with manageable AEs, and antitumor activity was observed in patients with EOC. CLINICALTRIALS.

GOV IDENTIFIER

NCT02361723.

Maintenance Treatment of Newly Diagnosed Advanced Ovarian Cancer: Time for a Paradigm Shift?

Recent data have demonstrated substantial efficacy with poly (ADP-ribose) polymerase (PARP) inhibitors as treatment and/or maintenance therapy in patients with newly diagnosed advanced epithelial ovarian cancer (EOC). Here, we review efficacy and safety results from four recent Phase III trials in newly diagnosed EOC: SOLO1 (olaparib), PAOLA-1 (olaparib in combination with bevacizumab), PRIMA (niraparib), and VELIA (veliparib). The implications of these data for current clinical practice and areas for future research are discussed, including ongoing studies of targeted agents in the newly diagnosed setting. Data from SOLO1, PAOLA-1, PRIMA, and VELIA confirm the benefit of PARP inhibitors (olaparib, niraparib, veliparib) for women with newly diagnosed EOC. The greatest benefit was seen in patients with a BRCA1 and/or BRCA2 mutation or in the homologous recombination deficiency (HRD)-test positive subgroup. These four well-conducted studies have generated practice-changing data. However, deciding how to apply these results in clinical practice is challenging, and substantial differences in trial design impede cross-trial comparisons. Recent PARP inhibitor approvals (olaparib, niraparib) in the newly diagnosed EOC setting have provided new maintenance treatment options for a broader patient population. The results of these studies call for personalized medicine based on biomarker profile and other factors, including tolerability, cost considerations, and physician and patient preference. Important areas for future research include appropriate use of both BRCA mutation and HRD testing to inform magnitude of PARP inhibitor benefit as well as exploring further options for patients who are HRD-test negative and for those who become PARP inhibitor resistant.

Gemogenovatucel-T (Vigil) maintenance immunotherapy: 3-year survival benefit in homologous recombination proficient (HRP) ovarian cancer

OBJECTIVE

Previously, Vigil demonstrated clinical benefit to prolong relapse free and overall survival in the BRCA wild-type (BRCA-wt), homologous recombination proficient (HRP) patient population. Here we provide long term follow up of 3 years in the HRP patient population enrolled in the Phase 2b VITAL study.

METHODS

HRP patients treated with Vigil (n = 25) or placebo (n = 20) who were enrolled in the Phase 2b, double-blind, placebo-controlled (VITAL study, NCT02346747) were followed for safety, OS and RFS. OS and RFS from time of randomization (immediately prior to maintenance therapy) and from debulking tissue procurement time points were analyzed by Kaplan-Meier (KM) and restricted mean survival time (RMST) analysis.

RESULTS

OS for Vigil treated patients at 3 years has not yet reached median OS time point (95% CI 41.6 months to not achieved) compared to 26.9 (95% CI 17.4 months to not achieved) in placebo treated patients (HR 0.417 p = 0.020). Three year RFS also showed benefit to Vigil (stratified HR 0.405, p = 0.011) and no long term toxicity to Vigil was observed. Three year OS for Vigil of 70% vs. 40% for placebo from time of randomization was observed (p = 0.019). RMST analysis was also significant for OS (45.7 vs. 32.8 months, p = 0.008) and RFS (p = 0.025).

CONCLUSION

In conclusion, results suggest durable activity of Vigil on RFS and OS and support further evaluation of Vigil in HRP ovarian cancer.

PARP Inhibitors in Combination with Radiotherapy: To Do or Not to Do?

Simple Summary

Despite the large use of inhibitors of Poly-ADP ribose polymerase (PARP-I), the feasibility and safety of their combination with radiotherapy (RT) are unclear. The combination may be particularly interesting in the oligometastatic setting in which patients may benefit from local RT during the treatment with PARP-I. The aim of the current review was to evaluate the outcome and the toxicity in patients with newly diagnosed or recurrent tumors treated with a combination of PARP-I and RT. A total of 12 clinical studies met the inclusion criteria and, despite the heterogeneity of the evaluated patient populations and tumor types, this review suggests that a combination approach is feasible even though the efficacy profile remains unclear.

Abstract

Background: Despite the large use of inhibitors of Poly-ADP ribose polymerase (PARP-I), the feasibility and safety of their combination with radiotherapy (RT) is unclear. Aim: We conducted a literature analysis with the aim to evaluate the efficacy and safety profile of a combination with RT and PARP-I. Method: The key issues for the current review were expressed in two questions according to the Population, Intervention, Control, Outcome (PICO) criteria: 1. What is the outcome and 2. What is the toxicity in patients treated with a combination of PARP-I and RT for a newly diagnosed or recurrent tumors? Results: A total of 12 clinical studies met the inclusion criteria including seven single-arm dose-escalation phase I studies, two phase II (two- and three-arms controlled trials) trials, one parallel-arm phase I study, and two phase I/II studies published between 2015 and 2021. RT was performed with photon beams and several schedules according to the clinical situation. The acute toxicity ≥ grade 3 ranged between 25% and >96%, which was divided into hematological or non-hematological adverse events. Conclusions: despite the heterogeneity of the evaluated patient populations and tumor types, and the limited number of the studies, this review suggests that a combination approach is feasible even though the efficacy profile remains unclear.

Discovery of 5-{4-[(7-Ethyl-6-oxo-5,6-dihydro-1,5-naphthyridin-3-yl)methyl]piperazin-1-yl}-N-methylpyridine-2-carboxamide (AZD5305): A PARP1-DNA Trapper with High Selectivity for PARP1 over PARP2 and Other PARPs

Poly-ADP-ribose-polymerase (PARP) inhibitors have achieved regulatory approval in oncology for homologous recombination repair deficient tumors including BRCA mutation. However, some have failed in combination with first-line chemotherapies, usually due to overlapping hematological toxicities. Currently approved PARP inhibitors lack selectivity for PARP1 over PARP2 and some other 16 PARP family members, and we hypothesized that this could contribute to toxicity. Recent literature has demonstrated that PARP1 inhibition and PARP1-DNA trapping are key for driving efficacy in a BRCA mutant background. Herein, we describe the structure- and property-based design of 25 (AZD5305), a potent and selective PARP1 inhibitor and PARP1-DNA trapper with excellent in vivo efficacy in a BRCA mutant HBCx-17 PDX model. Compound 25 is highly selective for PARP1 over other PARP family members, with good secondary pharmacology and physicochemical properties and excellent pharmacokinetics in preclinical species, with reduced effects on human bone marrow progenitor cells in vitro.

Diverse landscape of dermatologic toxicities from small-molecule inhibitor cancer therapy

BACKGROUND

Advances in molecular biology and genetics have contributed to breakthrough treatments directed at specific pathways associated with the development of cancer. Small-molecule inhibitors (Nibs) aimed at a variety of cellular pathways have been efficacious; however, they are associated with significant dermatologic toxicities.

METHODS

We conducted a comprehensive review of dermatologic toxicities associated with Nibs categorized into the following five groups: (a) mitogen-activated protein kinase; (b) growth factor/multi-tyrosine kinase; (c) cell division/DNA repair; (d) signaling associated with myeloproliferative neoplasms; and (e) other signaling pathways. Prospective phase I, II, or III clinical trials, retrospective literature reviews, systematic reviews/meta-analyses, and case reviews/reports were included for analysis.

RESULTS

Dermatologic toxicities reviewed were associated with every class of Nibs and ranged from mild to severe or life-threatening adverse skin reactions. Inflammatory reactions manifesting as maculopapular, papulopustular/acneiform, and eczematous lesions were frequent types of dermatologic toxicities seen with Nibs. Squamous cell carcinoma with keratoacanthoma-like features was associated with a subset of Nibs. Substantial overlap in dermatologic toxicities was found between Nibs.

CONCLUSIONS

Dermatologic toxicities from Nibs are diverse and may overlap between classes of Nibs. Recognition of the various types of toxicities from Nibs is critical for patient care in the era of "oncodermatology/dermatopathology."

Comparative safety and tolerability of approved PARP inhibitors in cancer: A systematic review and network meta-analysis

BACKGROUND

We aimed to evaluate comparative safety and tolerability of the approved PARP inhibitors in people with cancer.

METHODS

Eligible studies included randomized controlled trials comparing an approved PARP inhibitor (fluzoparib, olaparib, rucaparib, niraparib, or talazoparib) with placebo or chemotherapy in cancer patients. Outcomes of interest included: serious adverse event (SAE), discontinuation due to adverse event (AE), interruption of treatment due to AE, dose reduction due to AE, and specific grade 1-5 AEs.

RESULTS

Ten trials including 3763 participants and six treatments (olaparib, rucaparib, niraparib, talazoparib, placebo, and protocol-specified single agent chemotherapy) were identified. SAE and discontinuation of treatment did not differ significantly among the four approved PARP inhibitors. Regarding interruption of treatment and dose reduction due to AE, statistically significant differences and statistically non-significant trend were observed. Talazoparib is associated with a higher risk of interruption of treatment and dose reduction (excluding rucaparib) due to AE as compared with the other drugs. Niraparib showed a trend of lower risk of AE related dose reduction as compared with the other drugs. Furthermore, there were significant differences in specific grade 1-5 AE among the four drugs.

CONCLUSION

The safety profile of the four approved PARP inhibitors is comparable in terms of SAE and AE-related discontinuation of treatment. Statistically significant differences in the AEs spectrum and AEs related dose interruption and dose reduction demonstrated the prompt identification of AE and dose personalization seem mandatory to obtain maximal benefit from PARP inhibitors.

Population-adjusted indirect treatment comparison of maintenance PARP inhibitor with or without bevacizumab versus bevacizumab alone in women with newly diagnosed advanced ovarian cancer

BACKGROUND

In patients with newly diagnosed ovarian cancer, bevacizumab and poly(ADP-ribose) polymerase (PARP) inhibitors, alone or in combination, have shown benefit as maintenance treatment following platinum-based chemotherapy. However, no trials have compared a PARP inhibitor plus bevacizumab versus a PARP inhibitor, or a PARP inhibitor versus bevacizumab. We performed an unanchored population-adjusted indirect treatment comparison to estimate the relative efficacy and safety of maintenance treatments for newly diagnosed advanced ovarian cancer.

METHODS

Analyses were performed using aggregate data from the PRIMA trial and patient-level data from a subset of patients from the PAOLA-1 trial that met surgery and staging eligibility criteria of PRIMA. Propensity weights were used to match baseline characteristics of the PAOLA-1 subset to those of the PRIMA population. Analysis was performed in overall (biomarker-unselected) and homologous recombination repair deficiency (HRD)-positive populations.

RESULTS

A total of 595/806 (266/387 HRD-positive) PAOLA-1 patients were included. After matching, the effective sample size for PAOLA-1 was 532 (242 HRD-positive). Maintenance olaparib plus bevacizumab reduced the risk of disease progression or death by 43% [hazard ratio (HR) 0.57; 95% confidence interval (CI): 0.47-0.69] versus niraparib and by 40% (HR 0.60; 95% CI: 0.49-0.74) versus bevacizumab in the biomarker-unselected population and by 43% (HR 0.57; 95% CI: 0.41-0.79) and 60% (HR 0.40; 95% CI: 0.29-0.55), respectively, in the HRD-positive population. Progression-free survival (PFS) benefits of maintenance niraparib and bevacizumab arms were comparable in the biomarker-unselected population (HR 1.07; 95% CI: 0.87-1.32); however, niraparib showed a 30% reduced risk compared with bevacizumab (HR 0.70; 95% CI: 0.51-0.97) in the HRD-positive population.

CONCLUSIONS

In biomarker-unselected and HRD-positive patients, combination treatment with olaparib plus bevacizumab as maintenance treatment improves PFS for women with newly diagnosed advanced ovarian cancer compared with either bevacizumab or niraparib alone. Results are hypothesis generating and could guide randomised trial design.

Safety profile of poly (ADP-ribose) polymerase (PARP) inhibitors in cancer: a network meta-analysis of randomized controlled trials

Background

Poly (ADP-ribose) polymerase (PARP) inhibitors, which are among the most important breakthroughs in precision medicine, have played a crucial role in cancer treatment. Understanding the toxicity profiles of the different PARP inhibitors will improve strategic treatment in clinical practice.

Methods

PubMed, Cochrane Library, and Web of Science were systematically searched to include related studies published in English between January 2009 and February 2020. Only prospective, phase II and III randomized controlled trials were included. The following treatment groups were analyzed: niraparib, talazoparib, olaparib, rucaparib, conventional therapy (chemotherapy), one PARP inhibitor with one angiogenesis inhibitor, and placebo. Baseline data and adverse event data were extracted from the Bayesian random-effects network meta-analysis.

Results

Fourteen phase II and III randomized controlled trials (4,336 patients) were included. When considering grade 3–5 adverse events, olaparib may be a better choice (probability =57%), followed by conventional therapy (50%), talazoparib (45%), rucaparib (75%), niraparib (77%), and a PARP inhibitor with one angiogenesis inhibitor (94%). Niraparib and rucaparib had higher risks for hematological and gastrointestinal toxicities, respectively. Talazoparib was safer for gastrointestinal function. Constipation and neutropenia were less observed in olaparib, but the risks for anorexia increased. The combination of PARP inhibitor and angiogenesis inhibitor increased the risk of general, metabolic, and gastrointestinal disorders.

Conclusions

This network meta-analysis suggested that the toxicity spectrum of each PARP inhibitor is different. Olaparib had the best safety profile among all PARP inhibitors because of its mild toxicity and narrow spectrum. This study may guide clinicians and support further research.

Adherence to PARP inhibitor therapy among women with ovarian cancer

OBJECTIVE

The objective of this study was to evaluate medical adherence for patients with ovarian cancer who initiated treatment with a PARP inhibitor therapy, and to identify factors associated with nonadherence.

METHODS

We used the MarketScan Database to identify ovarian cancer patients who initiated PARP inhibitor therapy between January 1, 2008 and December 31, 2017. The primary outcome was adherence defined as ≥ 80% proportion of days covered (PDC). A secondary outcome included adherence assessed using the medication possession ratio (MPR). Multivariable logistic regression analysis was performed to assess relation between PDC and explanatory variables. Sensitivity analysis was performed to evaluate impact of dose-adjustments and toxicity-related delays on adherence.

RESULTS

Among 170,976 patients diagnosed with ovarian cancer, 151 patients met inclusion criteria. The median time from diagnosis to initiating therapy was 33 months. Overall, 40 (26.5%) were non-adherent based on a PDC less than 80%. Non-adherent patients were more likely to receive niraparib and have a longer duration of therapy (p < 0.05). We found no significant impact of age, comorbidities, insurance plan, or year of PARP inhibitor initiation on non-adherence. In a sensitivity analysis to assess different definition of adherence, non-adherence ranged from 11.3% to 41.1%. When accounting for possible dose-adjustments, 21.2% of patients were non-adherent.

CONCLUSION

This population based study of ovarian cancer patients found that a quarter of patients may be sub-optimally adherent to PARP inhibitor therapy. Future research should focus on identification of patients at risk for nonadherence and interventions to lower nonadherence among these patients.