Effectiveness and safety of poly (ADP-ribose) polymerase inhibitors in cancer therapy: A systematic review and meta-analysis

Efficacy and safety of veliparib plus chemotherapy for the treatment of lung cancer: A systematic review of clinical trials

BACKGROUND

As a poly-ADP ribose polymerase (PARP) inhibitor, veliparib has been identified as a potential therapeutic agent for lung cancer. The present study aimed to conduct a systematic review of clinical trials investigating the efficacy and safety of veliparib for treating lung cancer.

METHODS

PubMed, Scopus, the Web of Science, and Google Scholar were systematically searched up to October 30, 2022. Only randomized controlled trials (RCTs) evaluating the efficacy or safety of veliparib in the treatment of lung cancer patients were included. Studies were excluded if they were not RCTs, enrolled healthy participants or patients with conditions other than lung cancer, or investigated therapeutic approaches other than veliparib. The Cochrane risk-of-bias tool was used for quality assessment.

RESULTS

The seven RCTs (n = 2188) showed that patients treated with a combination of veliparib and chemotherapy had a significantly higher risk of adverse events, when compared to the control arm. There was no statistically significant difference in overall survival (OS) between those treated with veliparib plus chemotherapy and those receiving the standard therapies. Only two trials demonstrated an improvement in progression-free survival (PFS), and only one study found an increase in objective response rate (ORR). Furthermore, adding veliparib to standard chemotherapy showed no benefit in extending the duration of response (DoR) in any of the studies.

CONCLUSIONS

Only a small number of studies have found veliparib to be effective, in terms of improved OS, PFS, and ORR, while the majority of studies found no benefit for veliparib over standard treatment.

Simulating survival data when one subgroup lacks information

In this paper, we aim to show the process of simulating survival data when the distribution of the overall population and one subgroup (called "positive subgroup") as well as the proportion of the subgroup is known, while the distribution of the other subgroup (called "negative subgroup") is unknown. We propose a combination method which generates survival data of the positive subgroup and negative subgroup, respectively, and survival data of the overall population are the combination of the two subgroups. The parameters of the overall population and the positive subgroup need to satisfy certain constraints, otherwise the parameters may lead to contradictions. From simulation, we show that our proposed combination method can reflect the correlation between the test statistics of overall population and positive subgroup, which makes the simulated data more realistic and the results of simulation more reliable. Moreover, for a multiplicity control in trial design, the combination method can help to determine the α splitting strategy between primary endpoints, and is helpful in designs of clinical trials as shown in three applications.

Advanced Squamous Cell Carcinomas of the Pelvic and Perineal Region: A Comprehensive Genomic Profiling Study

BACKGROUND

Advanced pelvic squamous cell carcinoma (pSCC) is a broad category of cancers affecting different pelvic organs and usually featuring unfavorable clinical outcomes. Thus, we aimed to assess genomic differences among pSCC cases and learn whether pSCC could potentially benefit from targeted therapies and/or immunotherapy.

MATERIALS AND METHODS

A total of 1917 advanced pSCCs, including penile (penSCC), male urethral (murthSCC), male anal (manSCC), female urethral (furthSCC), vulvar (vulSCC), cervical (crvSCC), female anal (fanSCC), and vaginal (vagSCC), underwent comprehensive genomic profiling (CGP). We used hybrid capture-based CGP to evaluate recurrent genomic alterations (GAs). Tumor mutational burden (TMB) was determined on up to 1.1 Mb of sequenced DNA and microsatellite instability (MSI) was determined on up to 95 loci. Programmed cell-death-ligand-1 (PD-L1) expression was determined by immunohistochemistry (IHC; Dako 22C3).

RESULTS

PIK3CA was the most frequently identified potentially "actionable" GA (22%-43%), followed by mTOR pathway [PTEN (0%-18%), FBXW7 (7%-29%)], and cell-cycle GAs. DNA-damage response (DDR) GAs and receptor-tyrosine kinase (RTK) targeted options were uncommon. NOTCH1 GAs were present in >15% of penSCC and vulvSCC. TMB ≥10 mut/Mb was >15% in manSCC, fanSCC, crvSCC, and vagSCC. PD-L1 high expression was >18% in all pSCC except urthSCC, manSCC, and vagSCC. HPV-16/18 detection was highest in manSCC, fanSCC, and crvSCC.

CONCLUSION

Despite similar histology, pSCCs can differ in GAs and HPV status. Overall, PIK3CA is the most frequent potentially "targetable" GA followed by mTOR and cell cycle pathway. RTK and DDR GAs are rare in pSCC. Immunotherapy could be considered for pSCC management based on TMB and PD-L1 expression.

The immunoregulation effect of tumor microenvironment in pancreatic ductal adenocarcinoma

Pancreatic cancer has the seventh highest death rate of all cancers. The absence of any serious symptoms, coupled with a lack of early prognostic and diagnostic markers, makes the disease untreatable in most cases. This leads to a delay in diagnosis and the disease progresses so there is no cure. Only about 20% of cases are diagnosed early. Surgical removal is the preferred treatment for cancer, but chemotherapy is standard for advanced cancer, although patients can eventually develop drug resistance and serious side effects. Chemoresistance is multifactorial because of the interaction among pancreatic cancer cells, cancer stem cells, and the tumor microenvironment (TME). Nevertheless, more pancreatic cancer patients will benefit from precision treatment and targeted drugs. This review focuses on the immune-related components of TME and the interactions between tumor cells and TME during the development and progression of pancreatic cancer, including immunosuppression, tumor dormancy and escape. Finally, we discussed a variety of immune components-oriented immunotargeting drugs in TME from a clinical perspective.

PARP (Poly ADP-Ribose Polymerase) inhibitors for locally advanced or metastatic breast cancer

BACKGROUND

Locally advanced and metastatic breast cancer remains a challenge to treat. With emerging study results, it is important to interpret the available clinical data and apply the evidence offering the most effective treatment to the right patient. Poly(ADP Ribose) Polymerase (PARP) inhibitors are a new class of drug and their role in the treatment of locally advanced and metastatic breast cancer is being established.

OBJECTIVES

To determine the efficacy, safety profile, and potential harms of Poly(ADP-Ribose) Polymerase (PARP) inhibitors in the treatment of patients with locally advanced or metastatic breast cancer. The primary outcome of interest was overall survival; secondary outcomes included progression-free survival, tumour response rate, quality of life, and adverse events.

SEARCH METHODS

On 8 June 2020, we searched the Cochrane Breast Cancer Group Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE via OvidSP, Embase via OvidSP, World Health Organization International Clinical Trials Registry Platform (WHO ICTRP) search portal and ClinicalTrials.gov. We also searched proceedings from the major oncology conferences as well as scanned reference lists from eligible publications and contacted corresponding authors of trials for further information, where needed.

SELECTION CRITERIA

We included randomised controlled trials on participants with locally advanced or metastatic breast cancer comparing 1) chemotherapy in combination with PARP inhibitors, compared to the same chemotherapy without PARP inhibitors or 2) treatment with PARP inhibitors, compared to treatment with other chemotherapy. We included studies that reported on our primary outcome of overall survival and secondary outcomes including progression-free survival, tumour response rate, quality of life, and adverse events.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures defined by Cochrane. Summary statistics for the endpoints used hazard ratios (HR) with 95% confidence intervals (CI) for overall survival and progression-free survival, and odds ratios (OR) for response rate (RR) and toxicity.

MAIN RESULTS

We identified 49 articles for qualitative synthesis, describing five randomised controlled trials that were included in the quantitative synthesis (meta-analysis). A sixth trial was assessed as eligible but had ended prematurely and no data were available for inclusion in our meta-analysis. Risk of bias was predominately low to unclear across all studies except in regards to performance bias (3/5 high risk) and detection bias for the outcomes of quality of life (2/2 high risk) and reporting of adverse events (3/5 high risk). High-certainty evidence shows there may be a small advantage in overall survival (HR 0.87, 95% CI 0.76 to 1.00; 4 studies; 1435 patients). High-certainty evidence shows that PARP inhibitors offer an improvement in PFS in locally advanced/metastatic HER2-negative, BRCA germline mutated breast cancer patients (HR 0.63, 95% CI 0.56 to 0.71; 5 studies; 1474 patients). There was no statistical heterogeneity for these outcomes. Subgroup analyses for PFS outcomes based on trial level data were performed for triple-negative breast cancer, hormone-positive and/or HER2-positive breast cancer, BRCA1 and BRCA2 germline mutations, and patients who had received prior chemotherapy for advanced breast cancer or not. The subgroup analyses showed a persistent PFS benefit regardless of the subgroup chosen. Pooled analysis shows PARP inhibitors likely result in a moderate improvement in tumour response rate compared to other treatment arms (66.9% vs 48.9%; RR 1.39, 95% CI 1.24 to 1.54; 5 studies; 1185 participants; moderate-certainty evidence). The most common adverse events reported across all five studies included neutropenia, anaemia and fatigue. Grade 3 or higher adverse events probably occur no less frequently in patients receiving PARP inhibitors (59.4% for PARP arm versus 64.5% for non-PARP arm, RR 0.98, 95% CI 0.91 to 1.04; 5 studies; 1443 participants; moderate-certainty evidence). Only two studies reported quality of life outcomes so this was not amenable to meta-analysis. However, both studies that did assess quality of life showed PARP inhibitors were superior compared to physician's choice of chemotherapy in terms of participant-reported outcomes.

AUTHORS' CONCLUSIONS

In people with locally advanced or metastatic HER2-negative, BRCA germline mutated breast cancer, PARP inhibitors offer an improvement in progression-free survival, and likely improve overall survival and tumour response rates. This systematic review provides evidence supporting the use of PARP inhibitors as part of the therapeutic strategy for breast cancer patients in this subgroup. The toxicity profile for PARP inhibitors is probably no worse than chemotherapy but more information is required regarding quality of life outcomes, highlighting the importance of collecting such data in future studies. Future studies should also be powered to detect clinically important differences in overall survival and could focus on the role of PARP inhibitors in other relevant breast cancer populations, including HER2-positive, BRCA-negative/homologous recombination repair-deficient and Programmed Death-Ligand 1 (PDL1) positive.

Cost-Effectiveness of Genomic Test-Directed Olaparib for Metastatic Castration-Resistant Prostate Cancer

Purpose: The effectiveness of poly (adenosine diphosphate–ribose) polymerase (PARP) inhibitor olaparib for metastatic castration-resistant prostate cancer (MCRPC) with multiple loss-of-function alterations in genes that are involved in DNA repair has been demonstrated. We aimed to evaluate the cost-effectiveness of genomic test-directed olaparib on MCRPC from the US payer perspective.

Methods: A partitioned survival model was adopted to project the disease course of MCRPC had at least one gene alteration in BRCA1, BRCA2 and ATM (Scenario A) and has alterations in any of all 15 prespecified genes (Scenario B) after next-generation sequencing test. The efficacy and toxicity data were gathered from the PROfound trial. Clinical probabilities related to survival were estimated from the reported survival probabilities in each PROfound group. Cost and health preference data were derived from the literature. The incremental cost-effectiveness ratio (ICER) was measured. Subgroup analysis and sensitivity analysis were performed for exploring the model uncertainties.

Results: Olaparib yielded an additional 0.063 and 0.068 of quality-adjusted life year (QALY) with the augmented cost of $7,382 and saved the cost of $ 1,980 compared to standard care in scenario A and B, respectively, which yielded an ICER of $116,903/QALY and a cost-saving option. The lower weekly cost related to olaparib treatment led to the dominant findings in scenario B. The varied results between scenario A and B could be partly explained by different the number need to screen for identifying eligible patients who could be administered with olaparib, which sharply augmented the costs of the olaparib arm in scenario A. Subgroup analysis and sensitivity analysis revealed the results were generally robust in both of two scenarios.

Conclusion: The genomic test-directed olaparib is a preferred option compared with standard care strategy for men with MCRPC who had any of all 15 prespecified genes.

Cost-Effectiveness of Maintenance Olaparib for Germline BRCA-Mutated Metastatic Pancreatic Cancer

Background: Maintenance therapy with the PARP inhibitor olaparib for metastatic pancreatic cancer (MPC) with a germline BRCA1 or BRCA2 mutation has been shown to be effective. We aimed to evaluate the cost-effectiveness of maintenance olaparib for MPC from the US payer perspective. Materials and Methods: A partitioned survival model was adopted to project the disease course of MPC. Efficacy and toxicity data were gathered from the Pancreas Cancer Olaparib Ongoing (POLO) trial. Transition probabilities were estimated from the reported survival probabilities in each POLO group. Cost and health preference data were derived from the literature. The incremental cost-utility ratio, incremental net-health benefit, and incremental monetary benefit were measured. Subgroup analysis, one-way analysis, and probabilistic sensitivity analysis were performed to explore the model uncertainties. Results: Maintenance olaparib had an incremental cost-utility ratio of $191,596 per additional progression-free survival (PFS) quality-adjusted life-year (QALY) gained, with a high cost of $132,287 and 0.691 PFS QALY gained, compared with results for a placebo. Subgroup analysis indicated that maintenance olaparib achieved at least a 16.8% probability of cost-effectiveness at the threshold of $200,000/QALY. One-way sensitivity analyses revealed that the results were sensitive to the hazard ratio of PFS and the cost of olaparib. When overall survival was considered, maintenance olaparib had an incremental cost-utility ratio of $265,290 per additional QALY gained, with a high cost of $128,266 and 0.483 QALY gained, compared with results for a placebo. Conclusions: Maintenance olaparib is potentially cost-effective compared with placebo for patients with a germline BRCA mutation and MPC. Economic outcomes could be improved by tailoring treatment based on individual patient factors.

Proton and photon radiosensitization effects of niraparib, a PARP-1/-2 inhibitor, on human head and neck cancer cells

BACKGROUND

Combining photon or proton radiotherapy with targeted therapy shows promise for head and neck cancer (HNSCC). The poly (adenosine diphosphate [ADP]-ribose) polymerase-1/2 inhibitor niraparib targets DNA damage repair (DDR). We evaluated the effects of niraparib in combination with photons or protons, and its effects on the relative biological effectiveness (RBE) of protons, in human HNSCC cell lines.

METHODS

Radiosensitivity was assessed and RBE was calculated with clonogenic survival assays; unrepaired DNA double-strand breaks were evaluated using immunocytochemical analysis of 53BP1 foci.

RESULTS

Niraparib reduced colony formation in two of the four cell lines tested (P < .05), enhanced radiosensitivity in all four cell lines, delayed DDR (P < .05), and increased proton vs photon RBE.

CONCLUSION

Niraparib enhanced the sensitivity of four HNSCC cell lines to both photons and protons and increased the RBE of protons, possibly by inhibiting DDR. Niraparib may enhance the effectiveness of both photon and proton radiotherapy for patients with HNSCC.

A case report of a dramatic response to olaparib in a patient with metastatic pancreatic cancer harboring a germline BRCA2 mutation

RATIONALE

Pancreatic cancer (PC) is considered as one of the deadliest cancers all over the world. Germline and somatic BRCA1/2 mutations have been widely studied in breast and ovarian carcinomas as they have been found to enhance the risk for disease progression. Olaparib, an oral poly(adenosine diphosphate-ribose)polymerase (PARP) inhibitor, has been approved for the treatment strategy of ovarian cancer with any BRCA1/2 mutations. There is a lack of studies which focus on the treatment of other cancer with BRCA-Mutation.

PATIENT CONCERNS

This report describes a patient whose presenting complaints were "Physical examination showed that the pancreas was occupied for one month." He initially was diagnosed with stage IV PC based on conventional imaging and pathologic assessment. He had a known germline BRCA 2 mutation, which exhibited a good response to PARP inhibitor therapy.

DIAGNOSIS

Through the biopsy histopathological examination, imaging examination, and genetic testing, the patient was diagnosed as metastatic PC with BRCA2 mutation.

INTERVENTIONS

He received gemcitabine and albumin-bound paclitaxel chemotherapy from March 15, 2017 to June 30, 2017, and Nivolumab immunotherapy as the maintenance therapy. After serum CA-199 level increased, Olaparib was orally administered from August 17, 2017 to March. After tumor relapsed, he received multiple lines of chemotherapy, including Trametinib Oxaliplatin, S-1, bevacizumab, and irinotecan liposome injection till July 17, 2018.

OUTCOMES

We observed the patient had a good progression-free survival (7.4 months); the lesion of the pancreas was classified as partial disease through Olaparib treatment, which indicated significant shrinkage. But it is difficult to conclude whether such therapy could help prolong the overall survival for such patients.

LESSONS

The targeted therapy Olaparib showed early signs of potential in treating PC in patients with mutations of the BRCA genes. With emerging therapeutic modalities and next-generation sequencing development, it is increasingly relevant to consider mutation screenings of patients with PC.

First reported case of a collision tumor composed of pancreatic adenocarcinoma and retroperitoneal liposarcoma: a case report

BACKGROUND

Collision tumors are rare cases with two different tumor entities growing synchronously. While adenocarcinoma of the pancreas is the most common pancreatic tumor with an incidence of 10 per 100.000, retroperitoneal liposarcoma remains very rare. This is the first report of a collision tumor between these two tumor entities.

CASE PRESENTATION

Demographic details: The tumor was diagnosed in a 64 male Caucasian patient. Besides atrial fibrillation, arterial hypertension and a hypothyroidism there is no relevant medical history especially no history of cancer. Clinical details: During a routine check-up an unclassified tumor of the pancreatic tail was diagnosed. The lab showed no pathologies. Tumor markers were negative for carbohydrate antigen 19-9 and 72-4 (CA 19-9, CA 72-4) and carcinoembryonic antigen (CEA). Alpha-fetoprotein (AFP) and neuron specific enolase (NSE) were both elevated (AFP 97kU/l, (< 5,8kU/l) and NSE 30,0 μg/l (16,4 μg/l)). A computed tomography-guided core needle biopsy was performed which revealed a low-grade liposarcoma (G1). A CT scan showed no metastases. A surgical resection was recommended by the interdisciplinary tumor board.

INTERVENTIONS

A systematic left sided retroperitoneal compartment resection including en-bloc-left sided pancreatectomy, splenectomy, nephrectomy, hemicolectomy, adrenalectomy, partial gastrectomy and partial resection of the diaphragm was performed. Pathology revealed a collision tumor consisting of pancreatic adenocarcinoma that was classified pT3, pN2 (11/33 ece+) L1 V0 Pn0, R0; G2 [UICC Stage III] and a liposarcoma pT2, pN0 (0/33) L0 V0 Pn0, G1 [UICC Stage Ib]. The postoperative tumor board recommended an adjuvant chemotherapy with gemcitabine and capecitabine for the locally advanced pancreatic adenocarcinoma.

OUTCOME

At the latest follow-up (1 year after surgery) the patient was in good clinical condition and without evidence of tumor recurrence.

CONCLUSION

Collision tumors are rare and difficult to diagnose. This is the first description of a collision tumor composed of pancreatic adenocarcinoma and retroperitoneal liposarcoma. The reported case demonstrates that inconsistent diagnostic results (e.g. imaging and pathology) should raise suspicion concerning the diagnosis. Awareness of these rare cases might protect us from underdiagnosing patients and therefore leading to better patient care. There is evolving evidence that will lead to more personalized treatment options for somatic BRCA mutated pancreatic cancer.

The efficacy and safety of olaparib in the treatment of cancers: a meta-analysis of randomized controlled trials

Purpose

PARP inhibition is an exciting new anticancer strategy. As the first PARP inhibitor approved for the treatment of advanced BRCA-mutated ovarian cancer, olaparib has proven to be effective in the treatment of several solid tumors. We performed a meta-analysis of published randomized controlled trials to evaluate the efficacy and safety of olaparib in cancer patients.

Methods

PubMed, Embase, and oncology-conference proceedings were searched for relevant studies. End points were overall survival (OS), progression-free survival (PFS), overall response rate (ORR), and grade 3/4 adverse events. Pooled hazard ratio (HR)/risk ratio (RR) and 95% CI were calculated using random or fixed-effect models.

Results

Eight trials involving 1,957 patients were ultimately identified. The pooled analysis demonstrated that olaparib treatment significantly improved PFS (HR 0.62, 95% CI 0.47–0.82; P=0.001), OS (HR 0.82, 95% CI 0.73–0.93; P=0.001), and ORR (RR 1.38, 95% CI 1.16–1.65; P<0.001) when compared with therapy not containing olaparib. This association was further confirmed by sensitivity analysis. Additionally, olaparib treatment offered a significant survival benefit for patients with BRCA mutation. Moreover, treatment with olaparib was associated with a significant increase in risk of severe anemia.

Conclusion

Olaparib treatment has better treatment response compared with therapy not containing olaparib, whereas olaparib can increase the risk of severe anemia.

Final Report of a Phase I Trial of Olaparib with Cetuximab and Radiation for Heavy Smoker Patients with Locally Advanced Head and Neck Cancer

Purpose: Our goal was to evaluate the safety and toxicity of combining a PARP inhibitor, olaparib, with cetuximab and fractionated intensity-modulated radiotherapy for patients with locally advanced head and neck cancer and heavy smoking histories.Patients and Methods: Patients with ≥10 packs/year history of smoking were treated with olaparib at doses ranging from 25-200 mg orally twice daily beginning approximately 10 days prior to initiation of and with concurrent radiation (69.3 Gy in 33 fractions) using a time-to-event continual reassessment method model. Cetuximab was administered starting approximately 5 days prior to radiation per standard of care.Results: A total of 16 patients were entered onto the study, with 15 evaluable for acute toxicity. The most common treatment-related grade 3-4 side effects were radiation dermatitis and mucositis (38% and 69%, respectively). The MTD was determined to be 50 mg orally twice daily, but the recommended phase II dose was deemed to be 25 mg orally twice daily. At a median follow-up of 26 months, the actuarial median overall survival was 37 months, but was not reached for other endpoints. Two-year overall survival, progression-free survival, local control, and distant control rates were 72%, 63%, 72%, and 79%, respectively. Patients who continued to smoke during therapy experienced higher recurrence rates. MYC and KMT2A were identified as potential correlatives of response on gene amplification and mutational analysis.Conclusions: Olaparib at 25 mg orally twice daily with concurrent cetuximab and radiation was well tolerated with reduced dermatitis within the radiation field. Response rates were promising for this high-risk population. Clin Cancer Res; 24(20); 4949-59. ©2018 AACR.

Kinase inhibitors: the road ahead

Receptor tyrosine kinase signalling pathways have been successfully targeted to inhibit proliferation and angiogenesis for cancer therapy. However, kinase deregulation has been firmly demonstrated to play an essential role in virtually all major disease areas. Kinase inhibitor drug discovery programmes have recently broadened their focus to include an expanded range of kinase targets and therapeutic areas. In this Review, we provide an overview of the novel targets, biological processes and disease areas that kinase-targeting small molecules are being developed against, highlight the associated challenges and assess the strategies and technologies that are enabling efficient generation of highly optimized kinase inhibitors.

The efficacy and safety of tivantinib in the treatment of solid tumors: a systematic review and meta-analysis

BACKGROUND

Tivantinib was designed to kill cancers by targeting the mesenchymal-epithelial transition (MET) protein. Although numerous tivantinib clinical trials are ongoing, tivantinib's efficacy and safety are still not clear. This meta-analysis was done to evaluate tivantinib's efficacy and safety in solid tumor treatment.

MATERIALS AND METHODS

PUBMED, EMBASE, and other databases were searched for eligible tivantinib clinical trials. The hazard ratio (HR) and 95% confidence interval (CI) of progression-free and overall survival (PFS and OS, respectively) were pooled and analyzed to evaluate tivantinib's efficacy. Data concerning adverse events (Grade ≥ 3) were pooled to calculate relative risks (RRs) with 95% CI for tivantinib-treated compared with control arms.

FINDINGS

Patients (1824) from six randomized control trials (RCTs) were enrolled. Compared with controls, tivantinib produced a significant improvement in PFS (HR, 0.73; 95% CI 0.65-0.83) but not in OS. In the non-small-cell lung cancer (NSCLC) subgroup, tivantinib combined with erlotinib prolonged patients' PFS when compared with controls (HR, 0.75; 95% CI, 0.65-0.86). In the white population, tivantinib also significantly improve PFS between treatment and control arms (HR, 0.75; 95% CI, 0.65-0.87). Tivantinib significantly improved OS in patients with high levels of MET expression. Tivantinib was shown to increase the risk of anemia and neutropenia.

INTERPRETATION

Tivantinib was better in prolonging PFS (not OS) in patients with solid tumors. High MET expression cancers may benefit from tivantinib. Tivantinib appeared to be well-tolerated by patients.

"Back to a false normality": new intriguing mechanisms of resistance to PARP inhibitors

Several evidences have shown that BRCA mutations increased tumor-cells sensitivity to PARP inhibitors by synthetic lethality leading to an accelerated development of several compounds targeting the PARP enzymes system as anticancer agents for clinical setting. Most of such compounds have been investigated in ovarian and breast cancer, showing promising efficacy in BRCA-mutated patients. Recently clinical studies of PARP-inhibitors have been extended across different tumor types harboring BRCA-mutations, including also “BRCA-like” sporadic tumors with homologous recombination deficiency (HRD). This review summarizes the biological background underlying PARP-inhibition, reporting the results of the most relevant clinical trials carried out in patients treated with PARP inhibitors alone or in combination with chemotherapy. Molecular mechanisms responsible for the occurrence of both primary and acquired resistance have been elucidated, in order to support the development of new treatment strategies.

PD-1/PD-L1 and immunotherapy for pancreatic cancer

Therapy that targets programmed death 1 or programmed death 1 ligand 1 (PD-1/PD-L1), which are known as immune checkpoints, has been recently rapidly developing as oncotherapy for various carcinomas. However, this therapy has a poor effect on the treatment of pancreatic cancer with PD-1/PD-L1 blockade monotherapy. In this review, the development and limitations of anti-PD-1/PD-L1 monotherapy in pancreatic cancer are discussed. We then consider the underlying mechanism of anti-PD-1/PD-L1 monotherapy failure, combination strategies overcoming resistance to anti-PD-1/PD-L1 immunotherapy and the prospect of targeting PD-1/PD-L1 for the immunotherapy of pancreatic cancer.

Population pharmacokinetic analyses of the effect of carboplatin pretreatment on olaparib in recurrent or refractory women's cancers

PURPOSE

Combining olaparib with carboplatin was recently shown to be active in both BRCA and non-BRCA mutant cancers in a recent phase I/Ib combination trial. The optimal drug sequence recommended was carboplatin 1-day before olaparib. However, carboplatin pre-treatment induced a ~50% faster olaparib clearance.

METHODS

To further explore this drug interaction, a population pharmacokinetic (PK) model was designed that included a lag time parameter, a second absorption compartment from tablet formulation, a single distribution/elimination compartment, and covariance among the clearance and volume parameters.

RESULTS

Clearance (6.8 L/h) and volume (33 L) estimates were comparable with literature. The only significant covariate was the presence of carboplatin on olaparib clearance, consistent with published noncompartmental PK and in vitro data.

CONCLUSIONS

Simulations predicted lower steady-state peak/trough olaparib exposure through 24-36 h post carboplatin pre-treatment, but this effect was lost by day 2 and thus no dose adjustment is recommended.

Nanoformulation of Olaparib Amplifies PARP Inhibition and Sensitizes PTEN/TP53-Deficient Prostate Cancer to Radiation

The use of PARP inhibitors in combination with radiotherapy is a promising strategy to locally enhance DNA damage in tumors. Here we show that radiation-resistant cells and tumors derived from a Pten/Trp53-deficient mouse model of advanced prostate cancer are rendered radiation sensitive following treatment with NanoOlaparib, a lipid-based injectable nanoformulation of olaparib. This enhancement in radiosensitivity is accompanied by radiation dose-dependent changes in γ-H2AX expression and is specific to NanoOlaparib alone. In animals, twice-weekly intravenous administration of NanoOlaparib results in significant tumor growth inhibition, whereas previous studies of oral olaparib as monotherapy have shown no therapeutic efficacy. When NanoOlaparib is administered prior to radiation, a single dose of radiation is sufficient to triple the median mouse survival time compared to radiation only controls. Half of mice treated with NanoOlaparib + radiation achieved a complete response over the 13-week study duration. Using ferumoxytol as a surrogate nanoparticle, MRI studies revealed that NanoOlaparib enhances the intratumoral accumulation of systemically administered nanoparticles. NanoOlaparib-treated tumors showed up to 19-fold higher nanoparticle accumulation compared to untreated and radiation-only controls, suggesting that the in vivo efficacy of NanoOlaparib may be potentiated by its ability to enhance its own accumulation. Together, these data suggest that NanoOlaparib may be a promising new strategy for enhancing the radiosensitivity of radiation-resistant tumors lacking BRCA mutations, such as those with PTEN and TP53 deletions. Mol Cancer Ther; 16(7); 1279-89. ©2017 AACR.

Opportunities for the repurposing of PARP inhibitors for the therapy of non-oncological diseases

The recent clinical availability of the PARP inhibitor olaparib (Lynparza) opens the door for potential therapeutic repurposing for non-oncological indications. Considering (a) the preclinical efficacy data with PARP inhibitors in non-oncological diseases and (b) the risk-benefit ratio of treating patients with a compound that inhibits an enzyme that has physiological roles in the regulation of DNA repair, we have selected indications, where (a) the severity of the disease is high, (b) the available therapeutic options are limited, and (c) the duration of PARP inhibitor administration could be short, to provide first-line options for therapeutic repurposing. These indications are as follows: acute ischaemic stroke; traumatic brain injury; septic shock; acute pancreatitis; and severe asthma and severe acute lung injury. In addition, chronic, devastating diseases, where alternative therapeutic options cannot halt disease development (e.g. Parkinson's disease, progressive multiple sclerosis or severe fibrotic diseases), should also be considered. We present a preclinical and clinical action plan for the repurposing of PARP inhibitors.

LINKED ARTICLES

This article is part of a themed section on Inventing New Therapies Without Reinventing the Wheel: The Power of Drug Repurposing. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.2/issuetoc.

Prognostic and clinicopathological value of poly (adenosine diphosphate-ribose) polymerase expression in breast cancer: A meta-analysis

Background

Previous studies have shown that the poly (adenosine diphosphate-ribose) polymerase (PARP) level is a promising indicator of breast cancer. However, its prognostic value remains controversial. The present meta-analysis evaluated the prognostic value of PARP expression in breast cancer.

Materials and methods

Eligible studies were retrieved from the PubMed, Web of Science, Embase, and Cochrane Library databases through July 20, 2016. Studies investigating PARP expression as well as reporting survival data in breast cancer were included. Two independent reviewers carried out all literature searches. The pooled relative risk (RR) and hazard ratio (HR) with 95% confidence interval (95% CI) were applied to assess the association between PARP expression and the clinicopathological features and survival outcome in breast cancer.

Results

A total of 3506 patients from eight eligible studies were included. We found that higher PARP expression indicated a worse clinical outcome in early stage breast cancer, with a HR of 3.08 (95% CI, 1.14–8.29, P = 0.03) for disease-free survival and a HR of 1.82 (95% CI, 1.20–2.76; P = 0.005) for overall survival. Moreover, increased PARP expression was significantly associated with higher nuclear grade (RR, 1.51; 95% CI, 1.12–2.04; P = 0.008) in breast cancer. A similar correlation was detected in triple-negative breast cancer (TNBC; RR, 1.81; 95% CI, 1.04–3.17; P = 0.04).

Conclusions

Our findings indicated that elevated PARP expression correlated with worse prognosis in early stage breast cancer. Furthermore, high PARP expression was associated with higher nuclear grade and TNBC.

Genomic portfolio of Merkel cell carcinoma as determined by comprehensive genomic profiling: implications for targeted therapeutics

Merkel cell carcinoma is an ultra-rare cutaneous neuroendocrine cancer for which approved treatment options are lacking. To better understand potential actionability, the genomic landscape of Merkel cell cancers was assessed. The molecular aberrations in 17 patients with Merkel cell carcinoma were, on physician request, tested in a Clinical Laboratory Improvement Amendments (CLIA) laboratory (Foundation Medicine, Cambridge, MA) using next-generation sequencing (182 or 236 genes) and analyzed by N-of-One, Inc. (Lexington, MA). There were 30 genes harboring aberrations and 60 distinct molecular alterations identified in this patient population. The most common abnormalities involved the TP53 gene (12/17 [71% of patients]) and the cell cycle pathway (CDKN2A/B, CDKN2C or RB1) (12/17 [71%]). Abnormalities also were observed in the PI3K/AKT/mTOR pathway (AKT2, FBXW7, NF1, PIK3CA, PIK3R1, PTEN or RICTOR) (9/17 [53%]) and DNA repair genes (ATM, BAP1, BRCA1/2, CHEK2, FANCA or MLH1) (5/17 [29%]). Possible cognate targeted therapies, including FDA-approved drugs, could be identified in most of the patients (16/17 [94%]). In summary, Merkel cell carcinomas were characterized by multiple distinct aberrations that were unique in the majority of analyzed cases. Most patients had theoretically actionable alterations. These results provide a framework for investigating tailored combinations of matched therapies in Merkel cell carcinoma patients.

Akt inhibitor MK-2206 enhances the effect of cisplatin in gastric cancer cells

The phosphoinositide 3-kinase/Akt pathway activation commonly occurs in various types of human cancer and has an important role in chemoresistance. Combination of traditional chemotherapy drugs and molecular-targeted agents is a promising strategy for cancer therapy, which has shown enhanced cytotoxicity and lower drug resistance. The present study found that the Akt inhibitor, MK-2206, can increase the effect of cisplatin in the gastric cancer cell line AGS, which has higher Akt phosphorylation, but exhibited a poor combination effect in MKN-45 and MGC-803 cells, which have limited Akt activation. The MTT assay demonstrated that sequential treatment of cisplatin, followed by the Akt inhibitor, MK-2206, caused a synergistic effect of proliferation inhibition, and the apoptosis assay by propidium iodide/fluorescein isothiocyanate staining also showed that combination treatment induced more apoptosis compared to the monotherapy groups. Using western blot analysis, MK-2206 was shown to significantly suppress the phosphorylation of Akt (Ser473), however, the expression of total Akt remained the same, and the combination treatment also increased the expression of cleaved poly adenosine diphosphate ribose polymerase, which contributed to apoptosis.

The Changing Landscape of Breast Cancer: How Biology Drives Therapy

Breast cancer is the most prevalent life-threatening cancer in women. Optimizing therapy to increase cure rates in early stage disease, and improving life expectancy and palliation for advanced stages, are goals driving major areas of research. The armamentarium of targeted treatments for breast cancer is ever expanding as understanding of breast cancer biology deepens. A revolution in our treatment was heralded a decade ago by the introduction of trastuzumab for human epidermal receptor-2 positive (HER2+) disease resulting in remarkable reductions in recurrence and improvements in overall survival (OS). Advances continue to be made in other breast cancer subtypes targeting key activating pathways for therapeutic development. However, for these other targeted agents, improvement in OS has been elusive. This article focuses on the development of targeted therapy in breast cancer focusing primarily on the last 5 years, to illustrate that as we understand the complex pathways allowing the dysregulated cell to become malignant, it also propels us closer towards the promise of precision and personalized medicine.

Cellular Pathways in Response to Ionizing Radiation and Their Targetability for Tumor Radiosensitization

During the last few decades, improvements in the planning and application of radiotherapy in combination with surgery and chemotherapy resulted in increased survival rates of tumor patients. However, the success of radiotherapy is impaired by two reasons: firstly, the radioresistance of tumor cells and, secondly, the radiation-induced damage of normal tissue cells located in the field of ionizing radiation. These limitations demand the development of drugs for either radiosensitization of tumor cells or radioprotection of normal tissue cells. In order to identify potential targets, a detailed understanding of the cellular pathways involved in radiation response is an absolute requirement. This review describes the most important pathways of radioresponse and several key target proteins for radiosensitization.