Comparing niraparib versus platinum-taxane doublet chemotherapy as neoadjuvant treatment in patients with newly diagnosed homologous recombination-deficient stage III/IV ovarian cancer: study protocol for cohort C of the open-label, phase 2, randomized controlled multicenter OPAL trial

BACKGROUND

Maintenance therapy with niraparib, a poly(ADP-ribose) polymerase inhibitor, has been shown to extend progression-free survival in patients with newly diagnosed advanced ovarian cancer who responded to first-line platinum-based chemotherapy, regardless of biomarker status. However, there are limited data on niraparib's efficacy and safety in the neoadjuvant setting. The objective of Cohort C of the OPAL trial (OPAL-C) is to evaluate the efficacy, safety, and tolerability of neoadjuvant niraparib treatment compared with neoadjuvant platinum-taxane doublet chemotherapy in patients with newly diagnosed stage III/IV ovarian cancer with confirmed homologous recombination-deficient tumors.

METHODS

OPAL is an ongoing global, multicenter, randomized, open-label, phase 2 trial. In OPAL-C, patients will be randomized 1:1 to receive three 21-day cycles of either neoadjuvant niraparib or platinum-taxane doublet neoadjuvant chemotherapy per standard of care. Patients with a complete or partial response per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST v1.1) will then undergo interval debulking surgery; patients with stable disease may proceed to interval debulking surgery or alternative therapy at the investigator's discretion. Patients with disease progression will exit the study treatment and proceed to alternative therapy at the investigator's discretion. After interval debulking surgery, all patients will receive up to three 21-day cycles of platinum-taxane doublet chemotherapy followed by niraparib maintenance therapy for up to 36 months. Adult patients with newly diagnosed stage III/IV ovarian cancer eligible to receive neoadjuvant platinum-taxane doublet chemotherapy followed by interval debulking surgery may be enrolled. Patients must have tumors that are homologous recombination-deficient. The primary endpoint is the pre-interval debulking surgery unconfirmed overall response rate, defined as the investigator-assessed percentage of patients with unconfirmed complete or partial response on study treatment before interval debulking surgery per RECIST v1.1.

DISCUSSION

OPAL-C explores the use of niraparib in the neoadjuvant setting as an alternative to neoadjuvant platinum-taxane doublet chemotherapy to improve postsurgical residual disease outcomes for patients with ovarian cancer with homologous recombination-deficient tumors. Positive findings from this approach could significantly impact preoperative ovarian cancer therapy, particularly for patients who are ineligible for primary debulking surgery.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03574779. Registered on February 28, 2022.

Radiation therapy for triple-negative breast cancer: from molecular insights to clinical perspectives

INTRODUCTION

Triple-negative breast cancer (TNBC) lacks three common receptors, making traditional treatments less effective. This review highlights the importance of radiotherapy and emerging therapeutic strategies to enhance treatment outcomes in TNBC.

AREAS COVERED

We conducted a literature search on PubMed for publications from 2000 to 2023 to discuss the critical role of radiotherapy in managing TNBC, emphasizing its applications from locoregional control to improving survival rates. The review explores molecular mechanisms underlying TNBC's radiotherapy response, including DNA damage repair and apoptosis, with a focus on BRCA1/2 mutations and Poly (ADP-ribose) polymerase (PARP) inhibition. We summarize preclinical and clinical research on radiosensitization strategies, from gene-targeted therapies to immunotherapy combinations, and the impact of post-mastectomy radiation therapy on locoregional control. The potential of personalized treatment approaches, integrating molecular profiling, targeted radiosensitizers, and the synergistic effects of radiotherapy with immunotherapy, is also discussed.

EXPERT OPINION

Future TNBC treatment strategies should focus on precision medicine, integrating immunotherapy, developing novel radiosensitizers, and targeting biological pathways to overcome radioresistance. The integration of radiomics and artificial intelligence offers promising avenues for enhancing treatment personalization and efficacy, aiming to improve patient outcomes in TNBC.

ATARI trial: ATR inhibitor in combination with olaparib in gynecological cancers with ARID1A loss or no loss (ENGOT/GYN1/NCRI)

BACKGROUND

ARID1A (AT-rich interactive domain containing protein 1A) loss-of-function mutations have been reported in gynecological cancers, including rarer subtypes such as clear cell carcinoma. Preclinical studies indicate that ARID1A mutant cancers display sensitivity to ATR inhibition while tumors without ARID1A mutations may be sensitive to Ataxia telangiectasia and Rad3 related (ATR) inhibitors in combination with poly-ADP ribose polymerase (PARP) inhibitors.

PRIMARY OBJECTIVE

To determine whether the ATR inhibitor, ceralasertib, has clinical activity as a single agent and in combination with the PARP inhibitor, olaparib, in patients with ARID1A 'loss' and 'no loss' clear cell carcinomas and other relapsed gynecological cancers.

STUDY HYPOTHESIS

ARID1A deficient clear cell carcinoma of the ovary or endometrium is sensitive to ATR inhibition, while the combination of ATR and PARP inhibition has activity in other gynecological tumors, irrespective of ARID1A status.

TRIAL DESIGN

ATARI (ENGOT/GYN1/NCRI) is a multicenter, international, proof-of-concept, phase II, parallel cohort trial assessing ceralasertib activity as a single agent and in combination with olaparib in ARID1A stratified gynecological cancers. Patients with relapsed ovarian/endometrial clear cell carcinoma with ARID1A loss will receive ceralasertib monotherapy (cohort 1A). Relapsed ovarian/endometrial clear cell carcinoma patients with no ARID1A loss (cohort 2) or patients with other histological subtypes (endometrioid, carcinosarcoma, cervical) (cohort 3) will receive combination therapy (olaparib/ceralasertib). Treatment will continue until disease progression.

MAJOR INCLUSION/EXCLUSION CRITERIA

Patients with histologically confirmed recurrent clear cell (ovarian, endometrial, or endometriosis related), endometrioid (ovarian, endometrial, or endometriosis related), cervical (adenocarcinomas or squamous), or carcinosarcomas (ovarian or endometrial) are eligible. Patients progressing after ≥1 prior platinum with evidence of measurable (RECIST v1.1) radiological disease progression since last systemic anticancer therapy and prior to trial entry are eligible. Previous ATR or PARP inhibitor treatment is not permissible.

PRIMARY ENDPOINT

Best overall objective response rate (RECIST v1.1).

SAMPLE SIZE

A minimum of 40 and a maximum of 116.

ESTIMATED DATES FOR COMPLETING ACCRUAL AND PRESENTING RESULTS

Accrual is anticipated to be complete by the second quarter of 2022, with reporting of results by the fourth quarter of 2022. Overall accrual targets and reporting timelines are dependent on individual cohort progression to stage 2.

TRIAL REGISTRATION NUMBER

NCT0405269.

ATHENA (GOG-3020/ENGOT-ov45): a randomized, phase III trial to evaluate rucaparib as monotherapy (ATHENA-MONO) and rucaparib in combination with nivolumab (ATHENA-COMBO) as maintenance treatment following frontline platinum-based chemotherapy in ovarian cancer

Background

The optimal treatment strategy for women with newly diagnosed ovarian cancer has yet to be determined. Poly(ADP-ribose) polymerase (PARP) inhibitors have demonstrated substantial improvement in progression-free survival as monotherapy maintenance treatment in the frontline setting versus active surveillance. Furthermore, preclinical and early clinical studies have shown that PARP inhibitors and immune checkpoint inhibitors have synergistic antitumor activity and may provide an additional therapeutic option for patients in this population.

Primary Objectives

In women with newly diagnosed ovarian, fallopian tube, or peritoneal cancer, we wish to assess the efficacy of frontline maintenance treatment with the PARP inhibitor rucaparib versus placebo following response to platinum-based chemotherapy (ATHENA–MONO), and to assess the combination of rucaparib plus nivolumab (a programmed death receptor 1 (PD-1)–blocking monoclonal antibody) versus rucaparib alone (ATHENA–COMBO).

Study Hypothesis

(1) Maintenance therapy with rucaparib monotherapy may extend progression-free survival following standard treatment for ovarian cancer in the frontline setting. (2) The combination of nivolumab plus rucaparib may extend progression-free survival following standard treatment for ovarian cancer in the frontline setting compared with rucaparib alone.

Trial Design

ATHENA is an international, randomized, double-blind, phase III trial consisting of two independent comparisons (ATHENA–MONO and ATHENA–COMBO) in patients with newly diagnosed platinum-sensitive ovarian cancer. Patients are randomized 4:4:1:1 to the following: oral rucaparib+ intravenous nivolumab (arm A); oral rucaparib + intravenous placebo (arm B); oral placebo+ intravenous nivolumab (arm C); and oral placebo + intravenous placebo (arm D). The starting dose of rucaparib is 600 mg orally twice a day and nivolumab 480 mg intravenously every 4 weeks. ATHENA–MONO compares arm B with arm D to evaluate rucaparib monotherapy versus placebo, and ATHENA–COMBO evaluates arm A versus arm B to investigate the effects of rucaparib and nivolumab in combination versus rucaparib monotherapy. ATHENA–MONO and ATHENA–COMBO share a common treatment arm (arm B) but each comparison is independently powered.

Major Inclusion/Exclusion Criteria

Patients ≥18 years of age with newly diagnosed advanced, high-grade epithelial ovarian, primary peritoneal, or fallopian tube cancer who have achieved a response after completion of cytoreductive surgery and initial platinum-based chemotherapy are enrolled. No other prior treatment for ovarian cancer, other than the frontline platinum regimen, is permitted.

Primary Endpoint

The primary endpoint is investigator-assessed progression-free survival by Response Evaluation Criteria in Solid Tumors v1.1.

Sample Size

Approximately 1000 patients have been enrolled and randomized.

Estimated Dates for Completing Accrual and Presenting Results

The trial completed accrual in 2020. While dependent on event rates, primary results of ATHENA–MONO are anticipated in early 2022 and results of ATHENA–COMBO are anticipated to mature at a later date.

Trial Registration

This trial is registered at clinicaltrials.gov (NCT03522246).

Active Targeted Nanoparticles for Delivery of Poly(ADP-ribose) Polymerase (PARP) Inhibitors: A Preliminary Review

Nanotechnology has revolutionized novel drug delivery strategies through establishing nanoscale drug carriers, such as niosomes, liposomes, nanomicelles, dendrimers, polymeric micelles, and nanoparticles (NPs). Owing to their desirable cancer-targeting efficacy and controlled release, these nanotherapeutic modalities are broadly used in clinics to improve the efficacy of small-molecule inhibitors. Poly(ADP-ribose) polymerase (PARP) family members engage in various intracellular processes, including DNA repair, gene transcription, signal transduction, cell cycle regulation, cell division, and antioxidant response. PARP inhibitors are synthetic small-molecules that have emerged as one of the most successful innovative strategies for targeted therapy in cancer cells harboring mutations in DNA repair genes. Despite these advances, drug resistance and unwanted side effects are two significant drawbacks to using PARP inhibitors in the clinic. Recently, the development of practical nanotechnology-based drug delivery systems has tremendously improved the efficacy of PARP inhibitors. NPs can specifically accumulate in the leaky vasculature of the tumor and cancer cells and release the chemotherapeutic moiety in the tumor microenvironment. On the contrary, NPs are usually unable to permeate across the body's normal organs and tissues; hence the toxicity is zero to none. NPs can modify the release of encapsulated drugs based on the composition of the coating substance. Delivering PARP inhibitors without modulation often leads to the toxic effect; therefore, a delivery vehicle is essential to encapsulate them. Various nanocarriers have been exploited to deliver PARP inhibitors in different cancers. Through this review, we hope to cast light on the most innovative advances in applying PARP inhibitors for therapeutic purposes.

Human Mass Balance and Metabolite Profiling of [14 C]-Pamiparib, a Poly (ADP-Ribose) Polymerase Inhibitor, in Patients With Advanced Cancer

Pamiparib, a selective poly (ADP-ribose) polymerase 1/2 inhibitor, demonstrated tolerability and antitumor activity in patients with solid tumors at 60 mg orally twice daily. This phase 1 open-label study (NCT03991494; BGB-290-106) investigated the absorption, metabolism, and excretion (AME) of 60 mg [14 C]-pamiparib in 4 patients with solid tumors. The mass balance in excreta, blood, and plasma radioactivity and plasma pamiparib concentration were determined along with metabolite profiles in plasma, urine, and feces. Unchanged pamiparib accounted for the most plasma radioactivity (67.2% ± 10.2%). Pamiparib was rapidly absorbed with a median time to maximum plasma concentration (Cmax ) of 2.00 hours (range, 1.00-3.05 hours). After reaching Cmax , pamiparib declined in a biphasic manner, with a geometric mean terminal half-life (t1/2 ) of 28.7 hours. Mean cumulative [14 C]-pamiparib excretion was 84.7% ± 3.5%. Pamiparib was mainly cleared through metabolism, primarily via N-oxidation and oxidation of the pyrrolidine ring. A dehydrogenated oxidative product (M3) was the most abundant metabolite in biosamples. A mean of 2.11% and 1.11% of [14 C]-pamiparib was excreted as unchanged pamiparib in feces and urine, respectively, indicating near-complete absorption and low renal clearance of parent drug. Cytochrome P450 (CYP) phenotyping demonstrated CYP2C8 and CYP3A involvement in pamiparib metabolism. These findings provide an understanding of pamiparib AME mechanisms and potential drug-drug interaction liability.

Selective therapeutic strategy for p53-deficient cancer by targeting dysregulation in DNA repair

Breast carcinomas commonly carry mutations in the tumor suppressor p53, although therapeutic efforts to target mutant p53 have previously been unfruitful. Here we report a selective combination therapy strategy for treatment of p53 mutant cancers. Genomic data revealed that p53 mutant cancers exhibit high replication activity and express high levels of the Base-Excision Repair (BER) pathway, whereas experimental testing showed substantial dysregulation in BER. This defect rendered accumulation of DNA damage in p53 mutant cells upon treatment with deoxyuridine analogues. Notably, inhibition of poly (ADP-ribose) polymerase (PARP) greatly enhanced this response, whereas normal cells responded with activation of the p53-p21 axis and cell cycle arrest. Inactivation of either p53 or p21/CDKN1A conferred the p53 mutant phenotype. Preclinical animal studies demonstrated a greater anti-neoplastic efficacy of the drug combination (deoxyuridine analogue and PARP inhibitor) than either drug alone. This work illustrates a selective combination therapy strategy for p53 mutant cancers that will improve survival rates and outcomes for thousands of breast cancer patients.

Rationale for combination PARP inhibitor and antiangiogenic treatment in advanced epithelial ovarian cancer: A review

Inhibitors of poly(ADP-ribose) polymerase (PARP) and angiogenesis have demonstrated single-agent activity in women with advanced ovarian cancer. Recent studies have aimed to establish whether combination therapy can augment the response seen with PARP inhibitors or antiangiogenic agents alone. This review provides an overview of PARP inhibitors and antiangiogenics as monotherapy in women with advanced ovarian cancer, explores potential mechanisms of action of PARP inhibitor and antiangiogenic combination treatments, reviews efficacy and safety data from trials evaluating this combination, and outlines ongoing and future trials evaluating this combination, discussing these in the context of the current and future treatment landscape for women with advanced ovarian cancer. Sentinel studies evaluating PARP inhibitor (n = 8), antiangiogenic (n = 4), and combination (n = 7) therapy were identified in women with newly diagnosed (n = 7) and recurrent (n = 12) ovarian cancer. PARP inhibitors included olaparib (n = 9), niraparib (n = 4), rucaparib (n = 1), and veliparib (n = 1). Antiangiogenic agents included bevacizumab (n = 7) and cediranib (n = 4). PARP inhibitors combined with antiangiogenics demonstrated efficacy based on objective response rates and progression-free survival (PFS) in the relapsed disease setting. Maintenance therapy with the PARP inhibitor, olaparib, plus antiangiogenic therapy offered a significant PFS benefit versus the antiangiogenic alone in women with newly diagnosed advanced ovarian cancer who tested positive for homologous recombination deficiency. Combination therapy was tolerated, with no new safety signals reported compared with monotherapy trials. PARP inhibitors and antiangiogenics have changed the landscape of ovarian cancer treatment. The PARP inhibitor plus antiangiogenic combination is a novel treatment option that appears promising in the first-line advanced and recurrent ovarian cancer settings, although the role of this combination in recurrent disease requires further elucidation. Defining which patients are candidates for monotherapy or combination therapy is critical, taking into consideration safety profiles of therapies alone or in combination, and how these treatments should be sequenced in clinical practice.

The preferences of women with ovarian cancer for oral versus intravenous recurrence regimens

OBJECTIVE

To assess preferences of women with ovarian cancer regarding features of available anti-cancer regimens for platinum-resistant, biomarker-positive disease, with an emphasis on oral PARP inhibitor and standard intravenous (IV) chemotherapy regimens.

METHODS

A discrete-choice-experiment preferences survey was designed, tested, and administered to women with ovarian cancer, with 11 pairs of treatment profiles defined using seven attributes (levels/ranges): regimen (oral daily, IV weekly, IV monthly); probability of progression-free (PFS) at 6 months (40%-60%); probability of PFS at 2 years (10%-20%); nausea (none, moderate); peripheral neuropathy (none, mild, moderate); memory problems (none, mild); and total out-of-pocket cost ($0 to $10,000).

RESULTS

Of 123 participants, 38% had experienced recurrence, 25% were currently receiving chemotherapy, and 18% were currently taking a PARP inhibitor. Given attributes and levels, the relative importance weights (sum 100) were: 2-year PFS, 28; cost, 27; 6-month PFS, 19; neuropathy,14; memory problems, nausea, and regimen, all ≤5. To accept moderate neuropathy, participants required a 49% (versus 40%) chance of PFS at 6 months or 14% (versus 10%) chance at 2 years. Given a 3-way choice where PFS and cost were equal, 49% preferred a monthly IV regimen causing mild memory problems, 47% preferred an oral regimen causing moderate nausea, and 4% preferred a weekly IV regimen causing mild memory and mild neuropathy.

CONCLUSIONS

These findings challenge the assumption that oral anti-cancer therapies are universally preferred by patients and demonstrate that there is no "one size fits all" regimen that is preferable to women with ovarian cancer when considering recurrence treatment regimens.

Efficacy and safety of rucaparib in previously treated, locally advanced or metastatic urothelial carcinoma from a phase 2, open-label trial (ATLAS)

BACKGROUND

ATLAS evaluated the efficacy and safety of the PARP inhibitor rucaparib in patients with previously treated locally advanced/unresectable or metastatic urothelial carcinoma (UC).

METHODS

Patients with UC were enrolled independent of tumor homologous recombination deficiency (HRD) status and received rucaparib 600 mg BID. The primary endpoint was investigator-assessed objective response rate (RECIST v1.1) in the intent-to-treat and HRD-positive (loss of genome-wide heterozygosity ≥10%) populations. Key secondary endpoints were progression-free survival (PFS) and safety. Disease control rate (DCR) was defined post-hoc as the proportion of patients with a confirmed complete or partial response (PR), or stable disease lasting ≥16 weeks.

RESULTS

Of 97 enrolled patients, 20 (20.6%) were HRD-positive, 30 (30.9%) HRD-negative, and 47 (48.5%) HRD-indeterminate. Among 95 evaluable patients, there were no confirmed responses. However, reductions in the sum of target lesions were observed, including 6 (6.3%) patients with unconfirmed PR. DCR was 11.6%; median PFS was 1.8 months (95% CI, 1.6-1.9). No relationship was observed between HRD status and efficacy endpoints. Median treatment duration was 1.8 months (range, 0.1-10.1). Most frequent any-grade treatment-emergent adverse events were asthenia/fatigue (57.7%), nausea (42.3%), and anemia (36.1%). Of 64 patients with data from tumor tissue samples, 10 (15.6%) had a deleterious alteration in a DNA damage repair pathway gene, including four with a deleterious BRCA1 or BRCA2 alteration.

CONCLUSIONS

Rucaparib did not show significant activity in unselected patients with advanced UC regardless of HRD status. The safety profile was consistent with that observed in patients with ovarian or prostate cancer.

TRIAL REGISTRATION

This trial was registered in ClinicalTrials.gov (NCT03397394). Date of registration: 12 January 2018. This trial was registered in EudraCT (2017-004166-10).

Glycogen synthase kinase 3β inhibition synergizes with PARP inhibitors through the induction of homologous recombination deficiency in colorectal cancer

Monotherapy with poly ADP-ribose polymerase (PARP) inhibitors results in a limited objective response rate (≤60% in most cases) in patients with homologous recombination repair (HRR)-deficient cancer, which suggests a high rate of resistance in this subset of patients to PARP inhibitors (PARPi). To overcome resistance to PARPi and to broaden their clinical use, we performed high-throughput screening of 99 anticancer drugs in combination with PARPi to identify potential therapeutic combinations. Here, we found that GSK3 inhibitors (GSK3i) exhibited a strong synergistic effect with PARPi in a panel of colorectal cancer (CRC) cell lines with diverse genetic backgrounds. The combination of GSK3β and PARP inhibition causes replication stress and DNA double-strand breaks, resulting in increased anaphase bridges and abnormal spindles. Mechanistically, inhibition or genetic depletion of GSK3β was found to impair the HRR of DNA and reduce the mRNA and protein level of BRCA1. Finally, we demonstrated that inhibition or depletion of GSK3β could enhance the in vivo sensitivity to simmiparib without toxicity. Our results provide a mechanistic understanding of the combination of PARP and GSK3 inhibition, and support the clinical development of this combination therapy for CRC patients.

ICON 9-an international phase III randomized study to evaluate the efficacy of maintenance therapy with olaparib and cediranib or olaparib alone in patients with relapsed platinum-sensitive ovarian cancer following a response to platinum-based chemotherapy

BACKGROUND

Two novel biological agents-cediranib targeting angiogenesis, and olaparib targeting DNA repair processes-have individually led to an improvement in ovarian cancer control. The aim of ICON9 is to investigate the combination of cediranib and olaparib maintenance in recurrent ovarian cancer following platinum-based therapy.

PRIMARY OBJECTIVE

To assess the efficacy of maintenance treatment with olaparib in combination with cediranib compared with olaparib alone following a response to platinum-based chemotherapy in women with platinum-sensitive ovarian, fallopian tube or peritoneal cancer during first relapse.

STUDY HYPOTHESIS

Maintenance therapy with cediranib and olaparib in combination is associated with improved patient outcomes compared with olaparib alone.

TRIAL DESIGN

International phase III randomized controlled trial. Following a response to platinum-based chemotherapy patients are randomized 1:1 to either oral olaparib and cediranib (intervention arm) or oral olaparib alone (control arm).

MAJOR INCLUSION CRITERIA

Patients with a known diagnosis of high grade serous or endometrioid carcinoma of the ovary, fallopian tube or peritoneum, progressing more than 6 months after first-line platinum-based chemotherapy, who have responded to second-line platinum-based chemotherapy.

PRIMARY ENDPOINTS

Progression-free and overall survival. Co-primary endpoints to be assessed using a fixed-sequence gatekeeping approach: (1) progression-free survival, all patients; (2) progression-free survival, BRCA wild type; (3) overall survival, all patients; (4) overall survival, BRCA wild type.

SAMPLE SIZE

618 patients will be recruited.

ESTIMATED DATES FOR COMPLETING ACCRUAL AND PRESENTING RESULTS

Accrual is expected to be completed in 2024 with presentation of results in 2025.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT03278717.

Protective effects of PARP1-inhibitory compound in dry age-related macular degeneration

Poly (ADP-ribose) polymerase 1 (PARP1)-dependent cell death in the retinal pigment epithelium (RPE) is implicated in dry age-related macular degeneration (AMD). Although PARP1 inhibitors are available for treating dry AMD, their delivery route is not ideal for patients. The aim of this study was to test the efficacy of a novel PARP1-inhibitory compound (PIC) in vitro and in vivo. This study presents PIC, a novel small molecule, with superior efficacy to PARP1 inhibitors in the market. PIC demonstrated a distinctive inhibitory profile against PARP isotypes than the FDA-approved PARP1 inhibitors. PIC inhibited PARP1 activation at an IC50 of 0.41 ± 0.15 nM in an enzyme-based assay in vitro and at IC50 and EC50 in ARPE-19 cells of 0.11 ± 0.02 nM and 0.22 ± 0.02 nM, respectively, upon H2O2 insult. PIC also moderated mitochondrial fission and depolarization and maintained cellular energy levels under oxidative stress in ARPE-19 cells. Furthermore, PIC demonstrated good corneal penetration in a rat model, presenting PIC as a promising candidate for eye drop therapeutics for dry AMD. When PIC was administered as an eye drop formulation, RPE morphology was preserved, maintaining the thickness of the outer nuclear layers under sodium iodate (SI) treatment in rats. In SI-treated rabbits, eye drop administration of PIC also retained the structural and functional integrity when analyzed using funduscopy and electroretinogram. Collectively, our data portray PIC as an attractive treatment measure for dry AMD.

Elevated CXorf67 Expression in PFA Ependymomas Suppresses DNA Repair and Sensitizes to PARP Inhibitors

Ependymoma is the third most common pediatric tumor with posterior fossa group A (PFA) being its most aggressive subtype. Ependymomas are generally refractory to chemotherapies and thus lack any effective treatment. Here, we report that elevated expression of CXorf67 (chromosome X open reading frame 67), which frequently occurs in PFA ependymomas, suppresses homologous recombination (HR)-mediated DNA repair. Mechanistically, CXorf67 interacts with PALB2 and inhibits PALB2-BRCA2 interaction, thereby inhibiting HR repair. Concordantly, tumor cells with high CXorf67 expression levels show increased sensitivity to poly(ADP-ribose) polymerase (PARP) inhibitors, especially when combined with radiotherapy. Thus, our findings have revealed a role of CXorf67 in HR repair and suggest that combination of PARP inhibitors with radiotherapy could be an effective treatment option for PFA ependymomas.

Pamiparib dose escalation in Chinese patients with non-mucinous high-grade ovarian cancer or advanced triple-negative breast cancer

Background

The recommended phase 2 dose (RP2D) of pamiparib, an investigational PARP1/2 inhibitor, was established as 60 mg twice daily (BID) in a first‐in‐human (FIH) study (NCT02361723).

Methods

Chinese patients with advanced non‐mucinous high‐grade ovarian cancer (HGOC) or triple‐negative breast cancer (TNBC) whose disease either progressed despite standard therapy, or for which there is no standard therapy were enrolled in the dose‐escalation (DE) portion of a phase 1/2 study (NCT03333915). The primary endpoint was safety/tolerability; secondary objectives were pharmacokinetics and antitumor activity. BRCA1/2 mutation status was retrospectively evaluated.

Results

Nine HGOC and six TNBC patients (N = 15; n = 4, 20 mg; n = 4, 40 mg; n = 7, 60 mg) were enrolled; as of 30 September 2019, one HGOC patient remained on treatment. Seven patients (n = 5, HGOC; n = 2, TNBC) had germline BRCA1/2 mutation (gBRCA^mut); all HGOC patients were resistant/refractory to platinum. Asthenia and nausea (n = 12 each) were the most common treatment‐related adverse events (TRAEs). Decreased hemoglobin was the most common grade 3 TRAE (n = 3); no grade ≥4 AEs were observed. No dose‐limiting toxicities (DLTs) were reported. Pamiparib plasma exposure was similar to exposure observed in the FIH study after a single‐dose administration, albeit slightly higher at steady state. Among 13 RECIST‐evaluable patients, two with HGOC (gBRCA^mut, n = 1) achieved a confirmed partial response and six with HGOC (gBRCA^mut, n = 4) achieved stable disease; all TNBC RECIST‐evaluable patients (n = 5) reported progressive disease.

Conclusions

Pamiparib was generally well tolerated in Chinese patients, with durable responses observed in patients with HGOC. Based on these results, pamiparib 60 mg BID was confirmed as the RP2D.

Management of nausea and vomiting from poly(ADP-ribose) polymerase inhibitor therapy for advanced ovarian cancer

Poly(ADP-ribose) polymerase (PARP) inhibitors have rapidly emerged as a new class of daily oral chemotherapeutic agents that have the potential to dramatically alter the way in which primary peritoneal, fallopian tube and ovarian cancers are treated. However, the management of nausea and vomiting, the most common toxicities incurred by these agents, remains poorly understood. The purpose of this review is to provide an overview of current guidelines, antiemetic agents and management steps for patients experiencing nausea and vomiting associated with the use of PARP inhibitors.

PARP inhibition in the ovarian cancer patient: Current approvals and future directions

Poly (ADP-ribose) polymerase (PARP) inhibitors have transformed the therapeutic management of solid tumors, particularly ovarian cancer. Initially studied in BRCA deficient tumors, the Food and Drug Administration (FDA) indications have expanded to include other homologous recombination deficient tumors as well as biomarker-wildtype tumors. They have also gained momentum not only as a treatment strategy, but as a maintenance strategy as well. While PARP inhibitors were initially ev aluated in the recurrent setting, they have now moved to frontline therapy. This review will discuss the current FDA indications of the clinically available PARP inhibitors for treatment and maintenance therapies. We will then review the recently completed and ongoing clinical trials which may inform future clinical approvals.

Combination of PARP Inhibitor Olaparib, and PD-L1 Inhibitor Durvalumab, in Recurrent Ovarian Cancer: a Proof-of-Concept Phase II Study

PURPOSE

Preclinical studies suggest PARP inhibition (PARPi) induces immunostimulatory micromilieu in ovarian cancer thus complementing activity of immune checkpoint blockade. We conducted a phase II trial of PARPi olaparib and anti-PD-L1 durvalumab and collected paired fresh core biopsies and blood samples to test this hypothesis.

PATIENTS AND METHODS

In a single-center, proof-of-concept phase II study, we enrolled women aged ≥18 with recurrent ovarian cancer. All patients were immune checkpoint inhibitor-naïve and had measurable disease per RECISTv1.1, ECOG performance status 0-2, and adequate organ and marrow function. Patients received olaparib 300 mg twice daily and durvalumab 1,500 mg intravenously every 4 weeks until disease progression, unacceptable toxicity, or withdrawal of consent. Primary endpoint was overall response rate (ORR). Secondary objectives were safety and progression-free survival (PFS). Translational objectives included biomarker evaluation for relationships with clinical response and immunomodulatory effects by treatment.

RESULTS

Thirty-five patients with ovarian cancer [median, four prior therapies (IQR, 2-5.5), predominantly platinum-resistant (86%), BRCA wild-type (77%)] received at least one full cycle of treatment. ORR was 14% [5/35; 95% confidence interval (CI), 4.8%-30.3%]. Disease control rate (PR+SD) was 71% (25/35; 95% CI, 53.7%-85.4%). Treatment enhanced IFNγ and CXCL9/CXCL10 expression, systemic IFNγ/TNFα production, and tumor-infiltrating lymphocytes, indicating an immunostimulatory environment. Increased IFNγ production was associated with improved PFS [HR, 0.37 (95% CI, 0.16-0.87), P = 0.023], while elevated VEGFR3 levels were associated with worse PFS (HR, 3.22 (95% CI, 1.23-8.40), P = 0.017].

CONCLUSIONS

The PARPi and anti-PD-L1 combination showed modest clinical activity in recurrent ovarian cancer. Our correlative study results suggest immunomodulatory effects by olaparib/durvalumab in patients and indicate that VEGF/VEGFR pathway blockade would be necessary for improved efficacy of the combination.

Frontline PARP inhibitor maintenance therapy in ovarian cancer: A Society of Gynecologic Oncology practice statement

PARP inhibitors (PARPi) have shown have activity in the treatment of ovarian cancer. Previous studies documented activity in patients with germline (gBRCA) and tumor (tBRCA) BRCA mutations (BRCAm) for treatment in lieu of chemotherapy as well as in recurrent ovarian cancer as maintenance therapy. The recent data from four randomized phase 3 trials have established an important role for frontline PARPi maintenance therapy in ovarian cancer. While SOLO-1 only included BRCAm patients, PRIMA, VELIA, and PAOLA-1 enrolled broader patient populations. The magnitude of benefit of PARPi in these studies was consistently greatest in the BRCAm patients (germline or tumor). PARPi treatment also improved PFS in the HRD cohort but to a lesser degree than in patients with BRCAm. In secondary analyses, the overall impact of PARPi treatment in HR proficient patients, which comprise about 50% of ovarian cancers, was more limited than in the other subgroups. Data for overall survival, also a secondary endpoint, is currently immature for these four trials. Fatigue, hematologic, and GI toxicities are the most commonly noted adverse events with PARPi therapy. The recent FDA approvals of PARPi in the maintenance setting will enable clinicians to incorporate these into frontline armamentarium of ovarian cancer treatment.

Manage wisely: poly (ADP-ribose) polymerase inhibitor (PARPi) treatment and adverse events

Poly (ADP-ribose) polymerase (PARP) inhibitors (PARPi) have transformed the treatment landscape in front-line and recurrent high-grade serous ovarian cancer. Maintenance strategies with PARPi have been assessed in randomized phase III trials in ovarian cancer; switch maintenance in the case of olaparib, niraparib, and rucaparib; and concurrent followed by continuation maintenance with veliparib. These studies have shown progression-free survival advantage with PARPi maintenance, with no major adverse changes in the quality of life; however, overall survival data remain immature to date. PARPi have also been incorporated in clinical practice as a single-agent treatment strategy in high-grade serous ovarian cancer, mainly in women who harbor alterations in the BRCA1/2 genes or have alterations in the homologous recombination deficiency (HRD) pathway. Contemporary studies are looking into potentially synergistic combination strategies with anti-angiogenics and immune checkpoint inhibitors, among others. The expansion of PARPi treatment has not been limited to ovarian cancer; talazoparib is licensed in patients with HER2-negative breast cancer with germline BRCA mutations (BRCAm), and front-line olaparib maintenance in patients with pancreatic cancer with germline BRCAm. Numerous studies assessing PARPi either in monotherapy or in combination with other agents are ongoing in multiple tumors, including prostate, endometrial, brain, and gastric cancers. Many patients are being treated with PARPi, some for prolonged periods of time. As a result, a thorough knowledge of the potential short- and long-term adverse events and their management is warranted to improve patient safety, treatment efficacy, and towards maintaining an appropriate dose intensity.

Therapeutic applications of PARP inhibitors in ovarian cancer

Ovarian cancer is the most lethal gynecologic malignancy with a high recurrence rate. Poly(ADP-ribose) polymerase inhibitors (PARPi) are one of the most active new therapies for treatment of ovarian cancer. These treatment modalities are based on the mechanisms of "synthetic lethal" and "PARP trapping", especially for patients with homologous recombination deficiencies, and they demonstrate a high survival advantage. However, resistance to PARPi is an emerging problem. Identifying potential biomarkers to monitor the resistance and developing drug combination strategies are effective ways to address PARPi resistance. This review introduces the mechanisms of anticancer activity of PARPi and the developmental history in clinical research. Moreover, this paper systematically analyzes the functions of PARP family proteins. Additionally, this work highlights the treatment prospects of the combination of immunotherapy and PARPi in ovarian cancer. Finally, we propose several novel technologies to overcome the limitations of current preclinical studies and utilize them to select potential targets for combined drug therapy and identify biomarkers of PARPi resistance in ovarian cancer.

Rucaparib for patients with platinum-sensitive, recurrent ovarian carcinoma (ARIEL3): post-progression outcomes and updated safety results from a randomised, placebo-controlled, phase 3 trial

BACKGROUND

In ARIEL3, rucaparib maintenance treatment significantly improved progression-free survival versus placebo. Here, we report prespecified, investigator-assessed, exploratory post-progression endpoints and updated safety data.

METHODS

In this ongoing (enrolment complete) randomised, placebo-controlled, phase 3 trial, patients aged 18 years or older who had platinum-sensitive, high-grade serous or endometrioid ovarian, primary peritoneal, or fallopian tube carcinoma and an Eastern Cooperative Oncology Group performance status of 0 or 1 who had received at least two previous platinum-based chemotherapy regimens and responded to their last platinum-based regimen were randomly assigned (2:1) to oral rucaparib (600 mg twice daily) or placebo in 28-day cycles using a computer-generated sequence (block size of six with stratification based on homologous recombination repair gene mutation status, progression-free interval following penultimate platinum-based regimen, and best response to most recent platinum-based regimen). Patients, investigators, site staff, assessors, and the funder were masked to assignments. The primary endpoint of investigator-assessed progression-free survival has been previously reported. Prespecified, exploratory outcomes of chemotherapy-free interval (CFI), time to start of first subsequent therapy (TFST), time to disease progression on subsequent therapy or death (PFS2), and time to start of second subsequent therapy (TSST) and updated safety were analysed (visit cutoff Dec 31, 2017). Efficacy analyses were done in all patients randomised to three nested cohorts: patients with BRCA mutations, patients with homologous recombination deficiencies, and the intention-to-treat population. Safety analyses included all patients who received at least one dose of study treatment. This trial is registered with ClinicalTrials.gov, NCT01968213.

FINDINGS

Between April 7, 2014, and July 19, 2016, 564 patients were enrolled and randomly assigned to rucaparib (n=375) or placebo (n=189). Median follow-up was 28·1 months (IQR 22·0-33·6). In the intention-to-treat population, median CFI was 14·3 months (95% CI 13·0-17·4) in the rucaparib group versus 8·8 months (8·0-10·3) in the placebo group (hazard ratio [HR] 0·43 [95% CI 0·35-0·53]; p<0·0001), median TFST was 12·4 months (11·1-15·2) versus 7·2 months (6·4-8·6; HR 0·43 [0·35-0·52]; p<0·0001), median PFS2 was 21·0 months (18·9-23·6) versus 16·5 months (15·2-18·4; HR 0·66 [0·53-0·82]; p=0·0002), and median TSST was 22·4 months (19·1-24·5) versus 17·3 months (14·9-19·4; HR 0·68 [0·54-0·85]; p=0·0007). CFI, TFST, PFS2, and TSST were also significantly longer with rucaparib than placebo in the BRCA-mutant and homologous recombination-deficient cohorts. The most frequent treatment-emergent adverse event of grade 3 or higher was anaemia or decreased haemoglobin (80 [22%] patients in the rucaparib group vs one [1%] patient in the placebo group). Serious treatment-emergent adverse events were reported in 83 (22%) patients in the rucaparib group and 20 (11%) patients in the placebo group. Two treatment-related deaths have been previously reported in this trial; there were no new treatment-related deaths.

INTERPRETATION

In these exploratory analyses over a median follow-up of more than 2 years, rucaparib maintenance treatment led to a clinically meaningful delay in starting subsequent therapy and provided lasting clinical benefits versus placebo in all three analysis cohorts. Updated safety data were consistent with previous reports.

FUNDING

Clovis Oncology.

Extreme responses to immune checkpoint blockade following bipolar androgen therapy and enzalutamide in patients with metastatic castration resistant prostate cancer

BACKGROUND

Immune checkpoint inhibition has been shown to have limited efficacy in patients with metastatic prostate cancer. Prostate cancers that harbor certain homologous recombination (HR) DNA repair gene mutations, inactivating CDK12 mutations or have underlying mismatch repair deficiency may be effectively treated with immunotherapy. Combination therapy may improve clinical response rates to immune checkpoint blockade. We observed profound prostate-specific antigen (PSA) and/or objective responses to immune checkpoint blockade following prior treatment with bipolar androgen therapy (BAT) and enzalutamide.

METHODS

We report three cases of patients with metastatic castration resistant prostate cancer (mCRPC) undergoing therapy with anti-PD-1 inhibitors. All patients underwent both somatic molecular testing and germline genetic testing.

RESULTS

Two of the three patients with mCRPC harbored an inactivating mutation in an HR DNA repair gene (BRCA2, ATM). No patient demonstrated mismatch repair deficiency, nor were CDK12 alterations present. All three patients had been treated with BAT and enzalutamide before immune checkpoint blockade, a paradoxical approach for the treatment of mCRPC developed by our group.

CONCLUSIONS

These cases of mCRPC suggest that immune checkpoint blockade may have therapeutic potential in patients with prostate cancer, especially following immune activation ("priming") using BAT and enzalutamide.

PARP Inhibitors in Gynecologic Cancers: What Is the Next Big Development?

PURPOSE OF REVIEW

Conventional and novel applications of Poly(adenosine diphosphate [ADP]-ribose) polymerase (PARP) inhibitors (PARPi) are reviewed in the context of recently published clinical trials and preclinical data supporting rapidly expanding uses of this class of chemotherapy.

RECENT FINDINGS

PARPi block a pathway of DNA repair and target defects in homologous recombination repair (HRR), a pathway responsible for high-fidelity repair of double-strand breaks in DNA. BRCA1/2 proteins are essential to this pathway. Approximately 15-30% of women with ovarian cancer will have a germline or somatic BRCA mutation, and PARPi have shown promise in this population in a variety of settings. With growing understanding of the HRR pathway and its role in gynecologic malignancies, the potential applications of PARPi continue to expand. While the role of PARPi in gynecologic malignancies is most established in ovarian cancer, there are also promising applications in uterine and cervical cancer. We review current indications for PARPi use and promising applications of these medications in gynecologic malignancies.

The kinase polypharmacology landscape of clinical PARP inhibitors

Polypharmacology plays an important role in defining response and adverse effects of drugs. For some mechanisms, experimentally mapping polypharmacology is commonplace, although this is typically done within the same protein class. Four PARP inhibitors have been approved by the FDA as cancer therapeutics, yet a precise mechanistic rationale to guide clinicians on which to choose for a particular patient is lacking. The four drugs have largely similar PARP family inhibition profiles, but several differences at the molecular and clinical level have been reported that remain poorly understood. Here, we report the first comprehensive characterization of the off-target kinase landscape of four FDA-approved PARP drugs. We demonstrate that all four PARP inhibitors have a unique polypharmacological profile across the kinome. Niraparib and rucaparib inhibit DYRK1s, CDK16 and PIM3 at clinically achievable, submicromolar concentrations. These kinases represent the most potently inhibited off-targets of PARP inhibitors identified to date and should be investigated further to clarify their potential implications for efficacy and safety in the clinic. Moreover, broad kinome profiling is recommended for the development of PARP inhibitors as PARP-kinase polypharmacology could potentially be exploited to modulate efficacy and side-effect profiles.

BRCA1 intronic Alu elements drive gene rearrangements and PARP inhibitor resistance

BRCA1 mutant carcinomas are sensitive to PARP inhibitor (PARPi) therapy; however, resistance arises. BRCA1 BRCT domain mutant proteins do not fold correctly and are subject to proteasomal degradation, resulting in PARPi sensitivity. In this study, we show that cell lines and patient-derived tumors, with highly disruptive BRCT domain mutations, have readily detectable BRCA1 protein expression, and are able to proliferate in the presence of PARPi. Peptide analyses reveal that chemo-resistant cancers contain residues encoded by BRCA1 intron 15. Mechanistically, cancers with BRCT domain mutations harbor BRCA1 gene breakpoints within or adjacent to Alu elements in intron 15; producing partial gene duplications, inversions and translocations, and terminating transcription prior to the mutation-containing BRCT domain. BRCA1 BRCT domain-deficient protein isoforms avoid mutation-induced proteasomal degradation, support homology-dependent DNA repair, and promote PARPi resistance. Taken together, Alu-mediated BRCA1 gene rearrangements are responsible for generating hypomorphic proteins, and may represent a biomarker of PARPi resistance.

Health-related quality of life in patients with a germline BRCA mutation and metastatic pancreatic cancer receiving maintenance olaparib

BACKGROUND

Patients with metastatic pancreatic cancer often have a detriment in health-related quality of life (HRQoL). In the randomized, double-blind, phase III POLO trial progression-free survival was significantly longer with maintenance olaparib, a poly(ADP-ribose) polymerase inhibitor, than placebo in patients with a germline BRCA1 and/or BRCA2 mutation (gBRCAm) and metastatic pancreatic cancer whose disease had not progressed during first-line platinum-based chemotherapy. The prespecified HRQoL evaluation is reported here.

PATIENTS AND METHODS

Patients were randomized to receive maintenance olaparib (300 mg b.i.d.; tablets) or placebo. HRQoL was assessed using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30-item module at baseline, every 4 weeks until disease progression, at discontinuation, and 30 days after last dose. Scores ranged from 0 to 100; a ≥10-point change or difference between arms was considered clinically meaningful. Adjusted mean change from baseline was analysed using a mixed model for repeated measures. Time to sustained clinically meaningful deterioration (TSCMD) was analysed using a log-rank test.

RESULTS

Of 154 randomized patients, 89 of 92 olaparib-arm and 58 of 62 placebo-arm patients were included in HRQoL analyses. The adjusted mean change in Global Health Status (GHS) score from baseline was <10 points in both arms and there was no significant between-group difference [-2.47; 95% confidence interval (CI) -7.27, 2.33; P = 0.31]. Analysis of physical functioning scores showed a significant between-group difference (-4.45 points; 95% CI -8.75, -0.16; P = 0.04). There was no difference in TSCMD for olaparib versus placebo for GHS [P = 0.25; hazard ratio (HR) 0.72; 95% CI 0.41, 1.27] or physical functioning (P = 0.32; HR 1.38; 95% CI 0.73, 2.63).

CONCLUSIONS

HRQoL was preserved with maintenance olaparib treatment with no clinically meaningful difference compared with placebo. These results support the observed efficacy benefit of maintenance olaparib in patients with a gBRCAm and metastatic pancreatic cancer.

CLINCALTRIALS.GOV NUMBER

NCT02184195.

Dietary Compounds for Targeting Prostate Cancer

Prostate cancer is the third most common cancer worldwide, and the burden of the disease is increased. Although several chemotherapies have been used, concerns about the side effects have been raised, and development of alternative therapy is inevitable. The purpose of this study is to prove the efficacy of dietary substances as a source of anti-tumor drugs by identifying their carcinostatic activities in specific pathological mechanisms. According to numerous studies, dietary substances were effective through following five mechanisms; apoptosis, anti-angiogenesis, anti-metastasis, microRNA (miRNA) regulation, and anti-multi-drug-resistance (MDR). About seventy dietary substances showed the anti-prostate cancer activities. Most of the substances induced the apoptosis, especially acting on the mechanism of caspase and poly adenosine diphosphate ribose polymerase (PARP) cleavage. These findings support that dietary compounds have potential to be used as anticancer agents as both food supplements and direct clinical drugs.

Study protocols of three parallel phase 1 trials combining radical radiotherapy with the PARP inhibitor olaparib

BACKGROUND

Poly (ADP-ribose) Polymerase (PARP) inhibitors are promising novel radiosensitisers. Pre-clinical models have demonstrated potent and tumour-specific radiosensitisation by PARP inhibitors. Olaparib is a PARP inhibitor with a favourable safety profile in comparison to clinically used radiosensitisers including cisplatin when used as single agent. However, data on safety, tolerability and efficacy of olaparib in combination with radiotherapy are limited.

METHODS

Olaparib is dose escalated in combination with radical (chemo-)radiotherapy regimens for non-small cell lung cancer (NSCLC), breast cancer and head and neck squamous cell carcinoma (HNSCC) in three parallel single institution phase 1 trials. All trials investigate a combination treatment of olaparib and radiotherapy, the NSCLC trial also investigates a triple combination of olaparib, radiotherapy and concurrent low dose cisplatin. The primary objective is to identify the maximum tolerated dose of olaparib in these combination treatments, defined as the dose closest to but not exceeding a 15% probability of dose limiting toxicity. Each trial has a separate dose limiting toxicity definition, taking into account incidence, duration and severity of expected toxicities without olaparib. Dose escalation is performed using a time-to-event continual reassessment method (TITE-CRM). TITE-CRM enables the incorporation of late onset toxicity until one year after treatment in the dose limiting toxicity definition while maintaining an acceptable trial duration. Olaparib treatment starts two days before radiotherapy and continues during weekends until two days after radiotherapy. Olaparib will also be given two weeks and one week before radiotherapy in the breast cancer trial and HNSCC trial respectively to allow for translational research. Toxicity is scored using common terminology criteria for adverse events (CTCAE) version 4.03. Blood samples, and tumour biopsies in the breast cancer trial, are collected for pharmacokinetic and pharmacodynamic analyses.

DISCUSSION

We designed three parallel phase 1 trials to assess the safety and tolerability of the PARP inhibitor olaparib in combination with radical (chemo-)radiotherapy treatment regimens. PARP inhibitors have the potential to improve outcomes in patients treated with radical (chemo-)radiotherapy, by achieving higher locoregional control rates and/or less treatment associated toxicity.

TRIAL REGISTRATION

ClinicalTrials.gov Identifiers: NCT01562210 (registered March 23, 2012), NCT02227082 (retrospectively registered August 27, 2014), NCT02229656 (registered September 1, 2014).

Sequential Therapy with PARP and WEE1 Inhibitors Minimizes Toxicity while Maintaining Efficacy

We demonstrate that concurrent administration of poly(ADP-ribose) polymerase (PARP) and WEE1 inhibitors is effective in inhibiting tumor growth but poorly tolerated. Concurrent treatment with PARP and WEE1 inhibitors induces replication stress, DNA damage, and abrogates the G₂ DNA damage checkpoint in both normal and malignant cells. Following cessation of monotherapy with PARP or WEE1 inhibitors, effects of these inhibitors persist suggesting that sequential administration of PARP and WEE1 inhibitors could maintain efficacy while ameliorating toxicity. Strikingly, while sequential administration mirrored concurrent therapy in cancer cells that have high basal replication stress, low basal replication stress in normal cells protected them from DNA damage and toxicity, thus improving tolerability while preserving efficacy in ovarian cancer xenograft and patient-derived xenograft models.

OlympiAD final overall survival and tolerability results: Olaparib versus chemotherapy treatment of physician's choice in patients with a germline BRCA mutation and HER2-negative metastatic breast cancer

BACKGROUND

In the OlympiAD study, olaparib was shown to improve progression-free survival compared with chemotherapy treatment of physician's choice (TPC) in patients with a germline BRCA1 and/or BRCA2 mutation (BRCAm) and human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer (mBC). We now report the planned final overall survival (OS) results, and describe the most common adverse events (AEs) to better understand olaparib tolerability in this population.

PATIENTS AND METHODS

OlympiAD, a Phase III, randomized, controlled, open-label study (NCT02000622), enrolled patients with a germline BRCAm and HER2-negative mBC who had received ≤2 lines of chemotherapy for mBC. Patients were randomized to olaparib tablets (300 mg bid) or predeclared TPC (capecitabine, vinorelbine, or eribulin). OS and safety were secondary end points.

RESULTS

A total of 205 patients were randomized to olaparib and 97 to TPC. At 64% data maturity, median OS was 19.3 months with olaparib versus 17.1 months with TPC (HR 0.90, 95% CI 0.66-1.23; P = 0.513); median follow-up was 25.3 and 26.3 months, respectively. HR for OS with olaparib versus TPC in prespecified subgroups were: prior chemotherapy for mBC [no (first-line setting): 0.51, 95% CI 0.29-0.90; yes (second/third-line): 1.13, 0.79-1.64]; receptor status (triple negative: 0.93, 0.62-1.43; hormone receptor positive: 0.86, 0.55-1.36); prior platinum (yes: 0.83, 0.49-1.45; no: 0.91, 0.64-1.33). Adverse events during olaparib treatment were generally low grade and manageable by supportive treatment or dose modification. There was a low rate of treatment discontinuation (4.9%), and the risk of developing anemia did not increase with extended olaparib exposure.

CONCLUSIONS

While there was no statistically significant improvement in OS with olaparib compared to TPC, there was the possibility of meaningful OS benefit among patients who had not received chemotherapy for metastatic disease. Olaparib was generally well-tolerated, with no evidence of cumulative toxicity during extended exposure. Please see the article online for additional video content.

Pharmacokinetics and safety of olaparib tablets as monotherapy and in combination with paclitaxel: results of a Phase I study in Chinese patients with advanced solid tumours

PURPOSE

Chinese patients have been enrolled in multiple Phase III trials of the poly(ADP-ribose) polymerase (PARP) inhibitor olaparib (Lynparza); however, the pharmacokinetic (PK) profile of olaparib has not been investigated in this population. This two-part, open-label Phase I study was, therefore, carried out to determine the PK and safety profile of olaparib (tablet formulation) in Chinese patients with advanced solid tumours as monotherapy and in combination with paclitaxel (NCT02430311).

METHODS

The PK profile of olaparib 300 mg (twice daily [bid]; Cohort 1) as monotherapy after a single dose and at steady state, and 100 mg (bid; Cohort 2) as monotherapy (single dose and at steady state) and in combination (at steady state) with weekly paclitaxel (80 mg/m²) was assessed during Part A. Patients could continue to receive treatment (monotherapy, Cohort 1; combination therapy, Cohort 2) in Part B, which assessed safety and tolerability.

RESULTS

Twenty and 16 patients were enrolled into Cohorts 1 and 2, respectively. Steady-state olaparib exposure increased slightly less than proportionally with increasing monotherapy dose and inter-patient variability was high. A statistically significant decrease in olaparib exposure was seen when given in combination with paclitaxel. Discontinuation due to adverse events (AEs) was rare and haematological AEs were more common in patients receiving combination treatment.

CONCLUSIONS

The PK and safety profile of olaparib monotherapy in Chinese patients is consistent with that seen previously in Western and Japanese patients, and the recommended Phase III monotherapy tablet dose (300 mg bid) is suitable for use in this population.

Cost-Effectiveness of Niraparib Versus Routine Surveillance, Olaparib and Rucaparib for the Maintenance Treatment of Patients with Ovarian Cancer in the United States

OBJECTIVES

The aim was to evaluate the cost-effectiveness of niraparib compared with routine surveillance (RS), olaparib and rucaparib for the maintenance treatment of patients with recurrent ovarian cancer (OC).

METHODS

A decision-analytic model estimated the cost per quality-adjusted life-year (QALY) gained for niraparib versus RS, olaparib, and rucaparib from a US payer perspective. The model considered recurrent OC patients with or without germline BRCA mutations (gBRCAmut and non-gBRCAmut), who were responsive to their last platinum-based chemotherapy regimen. Model health states were: progression-free disease, progressed disease and dead. Mean progression-free survival (PFS) was estimated using parametric survival distributions based on ENGOT-OV16/NOVA (niraparib phase III trial), ARIEL3 (rucaparib phase III trial) and Study 19 (olaparib phase II trial). Mean overall survival (OS) benefit was estimated as double the mean PFS benefit based on the relationship between PFS and OS observed in Study 19. Costs included: drug, chemotherapy, monitoring, adverse events, and terminal care. EQ-5D utilities were estimated from trial data.

RESULTS

Compared to RS, niraparib was associated with an incremental cost-effectiveness ratio (ICER) of US$68,287/QALY and US$108,287/QALY for gBRCAmut and non-gBRCAmut, respectively. Compared to olaparib and rucaparib, niraparib decreased costs and increased QALYs, with a cost saving of US$8799 and US$22,236 versus olaparib and US$198,708 and US$73,561 versus rucaparib for gBRCAmut and non-gBRCAmut, respectively.

CONCLUSIONS

Niraparib was estimated to be less costly and more effective compared to olaparib and rucaparib, and the ICER fell within an acceptable range compared to RS. Therefore, niraparib may be considered a cost-effective maintenance treatment for patients with recurrent OC.

Targeted composite value-based endpoints in platinum-sensitive recurrent ovarian cancer

OBJECTIVES

FDA-approved treatments for platinum-sensitive recurrent ovarian cancer (PSROC) include bevacizumab and PARP inhibitors (PARPi); clinical decisions regarding therapy must be made prior to initiating chemotherapy. Using the American Society of Clinical Oncology (ASCO) and European Society of Medical Oncology (ESMO) value frameworks, we assessed relative values of concurrent/maintenance biologic therapies in PSROC.

METHODS

Value scores were calculated for key maintenance therapies based on randomized controlled trials: bevacizumab (OCEANS, GOG 213); olaparib (Study 19, SOLO2); niraparib (NOVA); rucaparib (ARIEL3). Personalized value scorecards were constructed for patients with germline/somatic-BRCA mutations, homologous recombination deficiency (HRD), and wild-type BRCA (wBRCA). ASCO value scores assess clinical benefit, toxicity, long-term survival, symptom palliation, treatment-free interval, and quality of life (QOL). ESMO value scores assess clinical benefit, toxicity, and QOL.

RESULTS

ASCO scores were highest for maintenance PARPi in germline/somatic-BRCA mutation cohorts: olaparib (SOLO2) = 47, (Study 19) = 62; niraparib = 50; rucaparib = 54. HRD cohorts had slightly lower scores: niraparib = 46; rucaparib = 37. wBRCA cohorts had the lowest scores: niraparib = 26; rucaparib = 26; and olaparib (Study 19) = 32, as did patients receiving bevacizumab (OCEANS) = 35, (GOG 213) = 26. ESMO scores demonstrated high-value for maintenance PARPi in germline/somatic-BRCA mutation cohorts and low-value for bevacizumab and PARPi in wBRCA cohorts.

CONCLUSIONS

The value of maintenance PARPi therapy depends heavily on BRCA status, with the highest value scores in germline/somatic-BRCA mutation cohorts. Personalized value scorecards provide a visual aid to assess the harm-benefit balance of maintenance PARPi for PSROC.

A phase 1 study of veliparib, a PARP-1/2 inhibitor, with gemcitabine and radiotherapy in locally advanced pancreatic cancer

Background

Locally advanced pancreatic cancer (LAPC) has a dismal prognosis with current treatment modalities and one-third of patients die from local progression of disease. Preclinical studies with orthotopic PC demonstrated dramatic synergy between radiotherapy (RT) and the poly(ADP-ribose) polymerase-1/2 inhibitor (PARPi), veliparib. We conducted a phase I trial of gemcitabine, radiotherapy and dose-escalated veliparib in LAPC.

Methods

This was a single institution investigator-initiated open-label, single-arm phase 1 clinical trial (NCT01908478). Weekly gemcitabine with daily IMRT and veliparib dose escalated using a Bayesian adaptive design were administered in treatment naïve LA or borderline resectable PC. The primary end point was identification of the MTD. Secondary endpoints included efficacy, characterization of PAR levels using ELISA, DDR alterations with targeted next generation sequencing and transcriptome analysis, tumor mutation burden (TMB) and microsatellite instability (MSI) status.

Findings

Thirty patients were enrolled. The MTD of veliparib was 40 mg BID with gemcitabine 400 mg/m² and RT (36 Gy/15 fractions). Sixteen DLTs were identified in 12 patients. Grade ≥ 3 adverse events included lymphopenia (96%) and anemia (36%). Median OS for all patients was 15 months. Median OS for DDR pathway gene altered and intact cases was 19 months (95% CI: 6.2–27.2) and 14 months (95% CI: 10.0–21.8), respectively. There were no significant associations between levels of PAR, TMB, or MSI with outcomes. The DDR transcripts PARP3 and RBX1 significantly correlated with OS.

Interpretation

This is the first report of a PARPi-chemoradiotherapy combination in PC. The regimen was safe, tolerable at the RP2D, and clinically active as an upfront treatment strategy in patients biologically unselected by upfront chemotherapy. Expression of the DDR transcripts, PARP3 and RBX1, were associated with OS suggesting validation in a follow up phase 2 study.

Fund

Phase One Foundation; National Institutes of Health [1R01CA188480-01A1, P01 CA098912]. Veliparib was provided by Abbvie.

PARP inhibitors affect growth, survival and radiation susceptibility of human alveolar and embryonal rhabdomyosarcoma cell lines

PURPOSE

PARP inhibitors (PARPi) are used in a wide range of human solid tumours but a limited evidence is reported in rhabdomyosarcoma (RMS), the most frequent childhood soft-tissue sarcoma. The cellular and molecular effects of Olaparib, a specific PARP1/2 inhibitor, and AZD2461, a newly synthesized PARP1/2/3 inhibitor, were assessed in alveolar and embryonal RMS cells both as single-agent and in combination with ionizing radiation (IR).

METHODS

Cell viability was monitored by trypan blue exclusion dye assays. Cell cycle progression and apoptosis were measured by flow cytometry, and alterations of specific molecular markers were investigated by, Real Time PCR, Western blotting and immunofluorescence experiments. Irradiations were carried out at a dose rate of 2 Gy (190 UM/min) or 4 Gy (380 UM/min). Radiosensitivity was assessed by using clonogenic assays.

RESULTS

Olaparib and AZD2461 dose-dependently reduced growth of both RH30 and RD cells by arresting growth at G2/M phase and by modulating the expression, activation and subcellular localization of specific cell cycle regulators. Downregulation of phospho-AKT levels and accumulation of γH2AX, a specific marker of DNA damage, were significantly and persistently induced by Olaparib and AZD2461 exposure, this leading to apoptosis-related cell death. Both PARPi significantly enhanced the effects of IR by accumulating DNA damage, increasing G2 arrest and drastically reducing the clonogenic capacity of RMS-cotreated cells.

CONCLUSIONS

This study suggests that the combined exposure to PARPi and IR might display a role in the treatment of RMS tumours compared with single-agent exposure, since stronger cytotoxic effects are induced, and compensatory survival mechanisms are prevented.

A RAD51 assay feasible in routine tumor samples calls PARP inhibitor response beyond BRCA mutation

Poly(ADP-ribose) polymerase (PARP) inhibitors (PARPi) are effective in cancers with defective homologous recombination DNA repair (HRR), including BRCA1/2-related cancers. A test to identify additional HRR-deficient tumors will help to extend their use in new indications. We evaluated the activity of the PARPi olaparib in patient-derived tumor xenografts (PDXs) from breast cancer (BC) patients and investigated mechanisms of sensitivity through exome sequencing, BRCA1 promoter methylation analysis, and immunostaining of HRR proteins, including RAD51 nuclear foci. In an independent BC PDX panel, the predictive capacity of the RAD51 score and the homologous recombination deficiency (HRD) score were compared. To examine the clinical feasibility of the RAD51 assay, we scored archival breast tumor samples, including PALB2-related hereditary cancers. The RAD51 score was highly discriminative of PARPi sensitivity versus PARPi resistance in BC PDXs and outperformed the genomic test. In clinical samples, all PALB2-related tumors were classified as HRR-deficient by the RAD51 score. The functional biomarker RAD51 enables the identification of PARPi-sensitive BC and broadens the population who may benefit from this therapy beyond BRCA1/2-related cancers.

Systematic review of treatment intensification using novel agents for chemoradiotherapy in rectal cancer

BACKGROUND

With the well established shift to neoadjuvant treatment for locally advanced rectal cancer, there is increasing focus on the use of radiosensitizers to improve the efficacy and tolerability of radiotherapy. There currently exist few randomized data exploring novel radiosensitizers to improve response and it is unclear what the clinical endpoints of such trials should be.

METHODS

A qualitative systematic review was performed according to the PRISMA guidelines using preset search criteria across the PubMed, Cochrane and Scopus databases from 1990 to 2017. Additional results were generated from the reference lists of included papers.

RESULTS

A total of 123 papers were identified, of which 37 were included; a further 60 articles were obtained from additional referencing to give a total of 97 articles. Neoadjuvant radiosensitization for locally advanced rectal cancer using fluoropyrimidine-based chemotherapy remains the standard of treatment. The oral derivative capecitabine has practical advantages over 5-fluorouracil, with equal efficacy, but the addition of a second chemotherapeutic agent has yet to show a consistent significant efficacy benefit in randomized clinical assessment. Preclinical and early-phase trials are progressing with promising novel agents, such as small molecular inhibitors and nanoparticles.

CONCLUSION

Despite extensive research and promising preclinical studies, a definite further agent in addition to fluoropyrimidines that consistently improves response rate has yet to be found.

Pharmacokinetic Effects and Safety of Olaparib Administered with Endocrine Therapy: A Phase I Study in Patients with Advanced Solid Tumours

INTRODUCTION

The PARP inhibitor olaparib is efficacious as monotherapy and has potential application in combination with endocrine therapy for the treatment of breast cancer. This phase I study assessed the safety and pharmacokinetic (PK) profiles of olaparib combined with tamoxifen, anastrozole or letrozole in patients with advanced solid tumours.

METHODS

During part A, PK profiles were assessed in three consecutive treatment periods: (1) olaparib (tablet) 300 mg bid, days 1-5 followed by a 4-day washout; (2) cohort 1, tamoxifen 60 mg loading dose qd days 10-13, 20 mg qd days 14-26; cohort 2, anastrozole 1 mg qd days 10-19; cohort 3, letrozole 2.5 mg qd days 10-38; (3) as for period 2, with concomitant olaparib 300 mg bid for 5 days. Patients could then enter part B and receive olaparib monotherapy (300 mg bid continuously). Safety was assessed in parts A and B until 12 months after the last patient entered part B.

RESULTS

Seventy-nine patients (20.3% with breast cancer) received treatment in part A; 72 completed part A and 69 entered part B. Anastrozole and letrozole had no effect on the PK profile of olaparib and vice versa. Co-administration with tamoxifen produced a modest decrease in exposure to olaparib [geometric least-squares mean (GLSmean) C_max,ss and AUC_0-τ decreased by 20% (90% CI 0.71-0.90) and 27% (0.63-0.84), respectively]. Exposure to tamoxifen was slightly increased when combined with olaparib [GLSmean C_max,ss and AUC_0-τ increased by 13% (1.06-1.22) and 16% (1.11-1.21), respectively]; however, the 90% CI fell within the 0.7-1.43 boundary and there were no changes in exposure to tamoxifen metabolites. The safety profile for olaparib alone and in combination with the antihormonal therapies was acceptable.

CONCLUSIONS

The combination of olaparib and either anastrozole, letrozole or tamoxifen was generally well tolerated, with no clinically relevant PK interactions identified.

FUNDING

AstraZeneca.

CLINICAL TRIAL REGISTRATION

NCT02093351.

Emerging therapeutic modalities of PARP inhibitors in breast cancer

Inhibition of Poly (ADP-ribose) polymerase (PARP) has shown marked benefit for breast cancer with homologous recombination deficiency, whether driven by defects in BRCA1, BRCA2, or other pathway components. Since the initial approval of olaparib, a mostly investigated PARP inhibitor (PARPi), the clinical development of PARPi in breast cancer treatment has been a major emphasis. Researches in investigating platinum-PARPi combination use compared with platinum monotherapy demonstrated promising benefit in metastatic BRCA mutated breast cancer or TNBC, while no such superiority was observed in the neoadjuvant setting of TNBC. Moreover, the utility of PARP inhibition in BRCA1/2 mutated breast cancer with different platinum-free interval was investigated. There was a clear association between clinical benefit with PARPi and platinum sensitivity, whereas partial efficacy of PARPi still occurs in platinum-resistant patients. In addition, proof-of-principle studies of immunotherapy combined with PARPi in breast cancer have obtained promising results, indicating the potential benefit of the combination therapy in patients with breast cancer. These efforts, contributing to maximize the utility of PARPi, may drive a new era of this agent after its first routine use. In this review, we summarized the utility of combining platinum-PARPi in BRCA mutated breast cancer or TNBC compared with platinum monotherapy and provided promising prospects of PARPi as maintenance therapy in breast cancer, as well as providing a strong rationale for testing immunotherapy combined with PARPi in breast cancer to expand the clinical utility of PARPi.

Front-line therapy of advanced ovarian cancer: new approaches

Background

The 5-year survival of ovarian cancer has slowly increased but to date much of this has been due to the use of more lines of treatment rather than better first-line therapy. In this setting, there has been little improvement over the past 15 years. The introduction of new treatments to extend time to first progression and overall survival remains a key objective of clinical research.

Design

The focus of research in the previous decade has been on the incorporation of anti-angiogenic therapy or dose-dense scheduling of paclitaxel (Taxol) to improve outcome. The new trials being conducted build on the knowledge gained and are focussing on two new areas of research, the use of PARP (poly-ADP ribose polymerase) inhibitors and immunotherapy.

Results

Ongoing randomised trials using PARP inhibitors or immune checkpoint inhibits are reviewed and the potential benefits and challenges of using these agents are discussed.

Conclusions

Improvements in outcome from some of the many open trials may present challenges; interpretation of the outcome data needs to be taken in the context of clinical benefit and a health-economic assessment. The latter is becoming ever-more important as the cost of trials with combinations of targeted therapy is very great.

A PET imaging agent for evaluating PARP-1 expression in ovarian cancer

BACKGROUND

Poly(ADP-ribose) polymerase (PARP) inhibitors are effective in a broad population of patients with ovarian cancer; however, resistance caused by low enzyme expression of the drug target PARP-1 remains to be clinically evaluated in this context. We hypothesize that PARP-1 expression is variable in ovarian cancer and can be quantified in primary and metastatic disease using a novel PET imaging agent.

METHODS

We used a translational approach to describe the significance of PET imaging of PARP-1 in ovarian cancer. First, we produced PARP1-KO ovarian cancer cell lines using CRISPR/Cas9 gene editing to test the loss of PARP-1 as a resistance mechanism to all clinically used PARP inhibitors. Next, we performed preclinical microPET imaging studies using ovarian cancer patient-derived xenografts in mouse models. Finally, in a phase I PET imaging clinical trial we explored PET imaging as a regional marker of PARP-1 expression in primary and metastatic disease through correlative tissue histology.

RESULTS

We found that deletion of PARP1 causes resistance to all PARP inhibitors in vitro, and microPET imaging provides proof of concept as an approach to quantify PARP-1 in vivo. Clinically, we observed a spectrum of standard uptake values (SUVs) ranging from 2-12 for PARP-1 in tumors. In addition, we found a positive correlation between PET SUVs and fluorescent immunohistochemistry for PARP-1 (r2 = 0.60).

CONCLUSION

This work confirms the translational potential of a PARP-1 PET imaging agent and supports future clinical trials to test PARP-1 expression as a method to stratify patients for PARP inhibitor therapy.

TRIAL REGISTRATION

Clinicaltrials.gov NCT02637934.

FUNDING

Research reported in this publication was supported by the Department of Defense OC160269, a Basser Center team science grant, NIH National Cancer Institute R01CA174904, a Department of Energy training grant DE-SC0012476, Abramson Cancer Center Radiation Oncology pilot grants, the Marsha Rivkin Foundation, Kaleidoscope of Hope Foundation, and Paul Calabresi K12 Career Development Award 5K12CA076931.

Targeted therapy for ovarian cancer: the rapidly evolving landscape of PARP inhibitor use

INTRODUCTION

Poly(ADP-ribose) polymerase (PARP) inhibitors are a targeted therapy option for ovarian cancer. The goal of this review was to organize and summarize the clinical trials evaluating PARP inhibitor therapy in ovarian cancer as monotherapy, maintenance therapy after partial or complete remission to therapy or as a part of a combination regimen.

EVIDENCE ACQUISITION

PubMed, ClinicalTrials.gov, data from the United States Food and Drug Administration (US FDA) and proceedings from scientific conferences were searched for published and unpublished data pertaining to clinical trials and approvals of PARP inhibitor use in ovarian cancer.

EVIDENCE SYNTHESIS

There have been 36 published phase 1, 2 and 3 studies evaluating the use of olaparib, niraparib, veliparib and rucaparib in ovarian cancer. Olaparib and rucaparib have been approved by the US FDA as monotherapy for advanced recurrent ovarian cancer. Niraparib and olaparib have been approved by the US FDA for maintenance therapy after partial or complete remission in recurrent ovarian cancer. There are currently ten phase 3 trials evaluating PARP inhibitors at various timepoints in ovarian cancer therapy including at the time of primary adjuvant therapy, as maintenance therapy after primary chemotherapy, as monotherapy for recurrent cancer and as maintenance therapy after chemotherapy for recurrence.

CONCLUSIONS

The landscape of PARP inhibitor use for ovarian cancer is rapidly evolving and PARP inhibitors have become more available as a targeted therapy option for ovarian cancer treatment.

Increased oxidative stress mediates the antitumor effect of PARP inhibition in ovarian cancer

PARP inhibitors have been widely tested in clinical trials, especially for the treatment of breast cancer and ovarian cancer, and were shown to be highly successful. Because PARP primarily functions in sensing and repairing DNA strand breaks, the therapeutic effect of PARP inhibition is generally believed to be attributed to impaired DNA repair. We here report that oxidative stress is also increased by PARP inhibition and mediates the antitumor effect. We showed that PARP1 is highly expressed in specimens of high grade serous ovarian carcinoma and its activity is required for unperturbed proliferation of ovarian cancer cells. Inhibition or depletion of PARP leads to not only an increase in DNA damage, but also an elevation in the levels of reactive oxygen species (ROS). Importantly, antioxidant N-acetylcysteine (NAC) significantly attenuated the induction of DNA damage and the perturbation of proliferation by PARP inhibition or depletion. We further showed that NADPH oxidases 1 and 4 were significantly upregulated by PARP inhibition and were partially responsible for the induction of oxidative stress. Depletion of NOX1 and NOX4 partially rescued the growth inhibition of PARP1-deficient tumor xenografts. Our findings suggest that in addition to compromising the repair of DNA damage, PARP inhibition or depletion may exert extra antitumor effect by elevating oxidative stress in ovarian cancer cells.

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PARP1 is overexpressed in ovarian cancer.

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PARP inhibition increases oxidative stress and oxidative DNA damage.

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PARP inhibition increases ROS by upregulating NOX1 and NOX4.

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Oxidative stress mediates the antitumor effect of PARP inhibition.

A Phase I Clinical Trial of the Poly(ADP-ribose) Polymerase Inhibitor Veliparib and Weekly Topotecan in Patients with Solid Tumors

Purpose: To determine the dose limiting toxicities (DLT), maximum tolerated dose (MTD), and recommended phase II dose (RP2D) of veliparib in combination with weekly topotecan in patients with solid tumors. Correlative studies were included to assess the impact of topotecan and veliparib on poly(ADP-ribose) levels in peripheral blood mononuclear cells, serum pharmacokinetics of both agents, and potential association of germline repair gene mutations with outcome.Experimental Design: Eligible patients had metastatic nonhematologic malignancies with measurable disease. Using a 3 + 3 design, patients were treated with veliparib orally twice daily on days 1-3, 8-10, and 15-17 and topotecan intravenously on days 2, 9, and 16 every 28 days. Tumor responses were assessed by RECIST.Results: Of 58 patients enrolled, 51 were evaluable for the primary endpoint. The MTD and RP2D was veliparib 300 mg twice daily on days 1-3, 8-10, and 15-17 along with topotecan 3 mg/m2 on days 2, 9, and 16 of a 28-day cycle. DLTs were grade 4 neutropenia lasting >5 days. The median number of cycles was 2 (1-26). The objective response rate was 10%, with 1 complete and 4 partial responses. Twenty-two patients (42%) had stable disease ranging from 4 to 26 cycles. Patients with germline BRCA1, BRCA2, or RAD51D mutations remained on study longer than those without homologous recombination repair (HRR) gene mutations (median 4 vs. 2 cycles).Conclusions: Weekly topotecan in combination with veliparib has a manageable safety profile and appears to warrant further investigation. Clin Cancer Res; 24(4); 744-52. ©2017 AACR.

Exposure-Response of Veliparib to Inform Phase II Trial Design in Refractory or Relapsed Patients with Hematological Malignancies

Purpose: A phase I trial of veliparib in combination with topotecan plus carboplatin (T+C) demonstrated a 33% objective response rate in patients with hematological malignancies. The objective is to perform exposure-response analysis to inform the phase II trial design.Experimental Design: Pharmacokinetic, efficacy, and safety data from 95 patients, who were administered 10 to 100 mg b.i.d. doses of veliparib for either 8, 14, or 21 days with T+C, were utilized for exposure-efficacy (objective response and overall survival) and exposure-safety (≥grade 3 mucositis) analysis. Multivariate cox proportional hazards and logistic regression analyses were conducted. The covariates evaluated were disease status, duration of treatment, and number of prior therapies.Results: The odds of having objective response were 1.08-fold with 1,000 ng/hr/mL increase in AUC, 1.8-fold with >8 days treatment, 2.8-fold in patients with myeloproliferative neoplasms (MPN), and 0.5-fold with ≥2 prior therapies. Based on analysis of overall survival, hazard of death decreased by 1.5% for 1,000 ng/hr/mL increase in AUC, 39% with >8 days treatment, 44% in patients with MPN, while increased by 19% with ≥2 prior therapies. The odds of having ≥grade 3 mucositis increased by 29% with 1,000 ng.h/mL increase in AUC.Conclusions: Despite shallow exposure-efficacy relationship, doses lower than 80 mg do not exceed veliparib single agent preclinical IC50 Shallow exposure-mucositis relationship also supports the 80-mg dose. Based on benefit/risk assessment, veliparib at a dose of 80 mg b.i.d. for at least 14 days in combination with T+C is recommended to be studied in MPN patients. Clin Cancer Res; 23(21); 6421-9. ©2017 AACR.