Randomized, Double-Blind Phase II Trial With Prospective Classification by ATM Protein Level to Evaluate the Efficacy and Tolerability of Olaparib Plus Paclitaxel in Patients With Recurrent or Metastatic Gastric Cancer

Arterial hypertension associated with PARPi: A meta-analysis of 41 placebo randomized controlled trials combined with a World Health Organization's pharmacovigilance study

BACKGROUND

Arterial hypertension has been recently reported from randomized controlled trials (RCTs) assessing poly (ADP-ribose) polymerase inhibitor (PARPi).

OBJECTIVE

In a context of increasing use of PARPi, it is crucial to properly assess risk and incidence of this adverse event for clinical practice.

METHODS

We performed a systematic review and meta-analysis in MEDLINE, Cochrane CENTRAL and ClinicalTrials.gov up to January 4, 2023 with an ongoing surveillance up to June 7, 2023. RCTs comparing PARPi to placebo in adult patients with solid tumors were included if hypertension was reported. The primary outcome was the summary risk ratio (RR, with 95% CIs) of any hypertension of PARPi class in placebo RCTs. Secondary outcomes were the summary risk and incidence of hypertension of each individual PARPi. To provide clinical features of PARPi-associated hypertension, we independently queried the WHO's pharmacovigilance database, up to September 1, 2022.

RESULTS

In total, 41 placebo RCTs (n = 15 264 adult patients) were included. PARPi class was not associated with an increased risk of hypertension compared with placebo. In individual analyses, the risk of hypertension was lower with olaparib than placebo (RR 0.77 [95% CI: 0.68-0.86], P < 0.01; I2 = 19%, χ2 P = 0.26). Niraparib monotherapy increased the risk of any (RR 2.84 [95% CI: 1.76-4.57], P < 0.01; I2 = 66%, χ2 P = 0.01) hypertension with a summary incidence of 19.87% (95% CI: 15.23-25.50). In real-life setting, niraparib-associated hypertension occurs within 20 days and was serious in 66%. Co-prescription of at least one antihypertensive or therapy-induced hypertension was reported in 20.5% or 14.4% of cases, respectively.

CONCLUSIONS

In a context of extensive assessment of niraparib in combination, these data reinforce the need of a close monitoring of this adverse event to preserve its clinical benefit on patients' survival.

Safety and hematological toxicities of PARP inhibitors in patients with cancer: a systematic review of randomized controlled trials and a pharmacovigilance analysis

INTRODUCTION

This study aimed to estimate the toxicities of PARP inhibitors (PARPis), based on randomized controlled trials (RCTs) and the FDA Adverse Event Reporting System (FAERS) database.

METHODS

Four electronic databases were searched from inception to 16 April 2024, for RCTs of approved PARPis. The primary and secondary outcomes were grade 3-5 adverse events (AEs) and grade 3-5 hematological AE, respectively. We conducted network meta-analyses to calculate the relative risks (RRs) and 95% confidence intervals (CIs) of outcomes. A disproportionality analysis was conducted to estimate the signals of hematological AEs associated with PARPis from the FAERS database.

RESULTS

Overall, 27 RCTs involving 11,067 patients with cancer were included. Olaparib had the best safety profile for any grade 3-5 AEs and hematological AEs among four approved PARPis. Olaparib did not increase the risk of thrombocytopenia (RR: 1.48; 95%CI: 0.64-3.39), but other PARPis did. Furthermore 14,780 hematological AE reports associated with PARPis were identified in the FAERS database, and all PARPis were associated with strong hematological AE signals. Hematological AEs mainly occurred within the first 3 months (80.84%) after PARPi initiation.

CONCLUSION

Olaparib had the best safety profile among five PARPis. PARPi-associated hematological AEs mainly occurred within the first 3 months.

REGISTRATION

PROSPERO (CRD42022385274).

Poly (adenosine diphosphate-ribose) polymerase inhibitors in the treatment of triple-negative breast cancer with homologous repair deficiency

Breast cancer (BC) is a highly heterogeneous disease, and the presence of germline breast cancer gene mutation (gBRCAm) is associated with a poor prognosis. Triple-negative breast cancer (TNBC) is a BC subtype, characterized by the absence of hormone and growth factor receptor expression, making therapeutic decisions difficult. Defects in the DNA damage response pathway due to mutation in breast cancer genes (BRCA 1/2) lead to homologous recombination deficiency (HRD). However, in HRD conditions, poly (adenosine diphosphate-ribose) polymerase (PARP) proteins repair DNA damage and lead to tumor cell survival. Biological understanding of HRD leads to the development of PARP inhibitors (PARPi), which trap PARP proteins and cause genomic instability and tumor cell lysis. HRD assessment can be an important biomarker in identifying gBRCAm patients with BC who could benefit from PARPi therapy. HRD can be identified by homologous recombination repair (HRR) gene-based assays, genomic-scarring assays and mutational signatures, transcription and protein expression profiles, and functional assays. However, gold standard methodologies that are robust and reliable to assess HRD are not available currently. Hence, there is a pressing need to develop accurate biomarkers identifying HRD tumors to guide targeted therapies such as PARPi in patients with BC. HRD assessment has shown fruitful outcomes in chemotherapy studies and preliminary evidence on PARPi intervention as monotherapy and combination therapy in HRD-stratified patients. Furthermore, ongoing trials are exploring the potential of PARPi in BC and clinically complex TNBC settings, where HRD testing is used as an adjunct to stratify patients based on BRCA mutations.

The efficacy and safety of PARP inhibitors in mCRPC with HRR mutation in second-line treatment: a systematic review and bayesian network meta-analysis

BACKGROUND

Poly (ADP- ribose) polymerase inhibitors (PARPi) has been increasingly adopted for metastatic castration-resistance prostate cancer (mCRPC) patients with homologous recombination repair deficiency (HRD). However, it is unclear which PARPi is optimal in mCRPC patients with HRD in 2nd -line setting.

METHOD

We conducted a systematic review of trials regarding PARPi- based therapies on mCRPC in 2nd -line setting and performed a Bayesian network meta-analysis (NMA). Radiographic progression-free survival (rPFS) was assessed as primary outcome. PSA response and adverse events (AEs) were evaluated as secondary outcomes. Subgroup analyses were performed according to specific genetic mutation.

RESULTS

Four RCTs comprised of 1024 patients (763 harbored homologous recombination repair (HRR) mutations) were identified for quantitative analysis. Regarding rPFS, olaparib monotherapy, rucaparib and cediranib plus olaparib showed significant improvement compared with ARAT. Olaparib plus cediranib had the highest surface under cumulative ranking curve (SUCRA) scores (87.5%) for rPFS, followed by rucaparib, olaparib and olaparib plus abiraterone acetate prednisone. For patients with BRCA 1/2 mutations, olaparib associated with the highest probability (98.1%) of improved rPFS. For patients with BRCA-2 mutations, olaparib and olaparib plus cediranib had similar efficacy. However, neither olaparib nor rucaparib showed significant superior effectiveness to androgen receptor-axis-targeted therapy (ARAT) in patients with ATM mutations. For safety, olaparib showed significantly lower ≥ 3 AE rate compared with cediranib plus olaparib (RR: 0.72, 95% CI: 0.51, 0.97), while olaparib plus cediranib was associated with the highest risk of all-grade AE.

CONCLUSION

PARPi-based therapy showed considerable efficacy for mCRPC patients with HRD in 2nd -line setting. However, patients should be treated accordingly based on their genetic background as well as the efficacy and safety of the selected regimen.

TRIAL REGISTRATION

CRD42023454079.

Upper Gastrointestinal Cancers and the Role of Genetic Testing

Beyond the few established hereditary cancer syndromes with an upper gastrointestinal cancer component, there is increasing recognition of the contribution of novel pathogenic germline variants (gPVs) to upper gastrointestinal carcinogenesis. The detection of gPVs has potential implications for novel treatment approaches of the index cancer patient as well as long-term implications for surveillance and risk-reducing measures for cancer survivors and far-reaching implications for the patients' family. With widespread availability of multigene panel testing, new associations may be identified with germline-somatic integration being critical to determining true causality of novel gPVs. Comprehensive cancer care should incorporate both somatic and germline testing.

Genomic characterization and detection of potential therapeutic targets for peritoneal mesothelioma in current practice

Peritoneal mesothelioma (PeM) is an aggressive tumor with limited treatment options. The current study aimed to evaluate the value of next generation sequencing (NGS) of PeM samples in current practice. Foundation Medicine F1CDx NGS was performed on 20 tumor samples. This platform assesses 360 commonly somatically mutated genes in solid tumors and provides a genomic signature. Based on the detected mutations, potentially effective targeted therapies were identified. NGS was successful in 19 cases. Tumor mutational burden (TMB) was low in 10 cases, and 11 cases were microsatellite stable. In the other cases, TMB and microsatellite status could not be determined. BRCA1 associated protein 1 (BAP1) mutations were found in 32% of cases, cyclin dependent kinase inhibitor 2A/B (CDKN2A/B) and neurofibromin 2 (NF2) mutations in 16%, and ataxia-telangiectasia mutated serine/threonine kinase (ATM) in 11%. Based on mutations in the latter two genes, potential targeted therapies are available for approximately a quarter of cases (i.e., protein kinase inhibitors for three NF2 mutated tumors, and polyADP-ribose polymerase inhibitors for two ATM mutated tumors). Extensive NGS analysis of PeM samples resulted in the identification of potentially effective targeted therapies for about one in four patients. Although these therapies are currently not available for patients with PeM, ongoing developments might result in new treatment options in the future.

Mutational signature-based identification of DNA repair deficient gastroesophageal adenocarcinomas for therapeutic targeting

Homologous recombination (HR) and nucleotide excision repair (NER) are the two most frequently disabled DNA repair pathways in cancer. HR-deficient breast, ovarian, pancreatic and prostate cancers respond well to platinum chemotherapy and PARP inhibitors. However, the frequency of HR deficiency in gastric and esophageal adenocarcinoma (GEA) still lacks diagnostic and functional validation. Using whole exome and genome sequencing data, we found that a significant subset of GEA, but very few colorectal adenocarcinomas, show evidence of HR deficiency by mutational signature analysis (HRD score). High HRD gastric cancer cell lines demonstrated functional HR deficiency by RAD51 foci assay and increased sensitivity to platinum chemotherapy and PARP inhibitors. Of clinical relevance, analysis of three different GEA patient cohorts demonstrated that platinum treated HR deficient cancers had better outcomes. A gastric cancer cell line with strong sensitivity to cisplatin showed HR proficiency but exhibited NER deficiency by two photoproduct repair assays. Single-cell RNA-sequencing revealed that, in addition to inducing apoptosis, cisplatin treatment triggered ferroptosis in a NER-deficient gastric cancer, validated by intracellular GSH assay. Overall, our study provides preclinical evidence that a subset of GEAs harbor genomic features of HR and NER deficiency and may therefore benefit from platinum chemotherapy and PARP inhibitors.

NCI10066: a Phase 1/2 study of olaparib in combination with ramucirumab in previously treated metastatic gastric and gastroesophageal junction adenocarcinoma

BACKGROUND

Our preclinical work revealed tumour hypoxia induces homologous recombination deficiency (HRD), increasing sensitivity to Poly (ADP-ribose) polymerase inhibitors. We aimed to induce tumour hypoxia with ramucirumab thereby sensitising tumours to olaparib.

PATIENTS AND METHODS

This multi-institution single-arm Phase 1/2 trial enrolled patients with metastatic gastroesophageal adenocarcinoma refractory to ≥1 systemic treatment. In dose escalation, olaparib was evaluated at escalating dose levels with ramucirumab 8 mg/kg day 1 in 14-day cycles. The primary endpoint of Phase 1 was the recommended Phase 2 dose (RP2D), and in Phase 2 the primary endpoint was the overall response rate (ORR).

RESULTS

Fifty-one patients received ramucirumab and olaparib. The RP2D was olaparib 300 mg twice daily with ramucirumab 8 mg/kg. In evaluable patients at the RP2D the ORR was 6/43 (14%) (95% CI 4.7-25.6). The median progression-free survival (PFS) was 2.8 months (95% CI 2.3-4.2) and median overall survival (OS) was 7.3 months (95% CI 5.7-13.0). Non-statistically significant improvements in PFS and OS were observed for patients with tumours with mutations in HRD genes.

CONCLUSIONS

Olaparib and ramucirumab is well-tolerated with efficacy that exceeds historical controls with ramucirumab single agent for gastric cancer in a heavily pre-treated patient population.

Advances in DNA damage response inhibitors in colorectal cancer therapy

One potential cause of cancer is genomic instability that arises in normal cells due to years of DNA damage in the body. The clinical application of radiotherapy and cytotoxic drugs to treat cancer is based on the principle of damaging the DNA of cancer cells. However, the benefits of these treatments also have negative effects on normal tissue. While there have been notable advancements in molecular-driven therapy and immunotherapy for colorectal cancer (CRC), a considerable portion of patients with advanced CRC do not experience any benefits from these treatments, leading to a poor prognosis. In recent years, targeted therapy aimed at suppressing the DNA damage response (DDR) in cancer cells has emerged as a potential treatment option for CRC patients, offering them more choices for treatment. Currently, the integration of DDR and clinical intervention remains in the exploratory phase. This review primarily elucidates the fundamental principles of DDR inhibitors, provides an overview of their current clinical application status in CRC, and discusses the advancements as well as limitations observed in relevant studies.

Promising Response of Olaparib in Patient With Germline ATM-Mutated Metastatic Gastric Cancer

Gastric cancer ranks as the fifth leading cause of global cancer incidences, exhibiting varied prevalence influenced by geographical, ethnic, and lifestyle factors, as well as Helicobacter pylori infection. The ATM gene on chromosome 11q22 is vital for genomic stability as an initiator of the DNA damage response, and mutations in this gene have been associated with various cancers. Poly ADP-ribose polymerase (PARP) inhibitors, such as olaparib, have shown efficacy in cancers with homologous recombination repair deficiencies, notably in those with ATM mutations. Here, we present a case of a 66-year-old patient with germline ATM-mutated metastatic gastric cancer with very high CA 19-9 (48 000 units/mL) who demonstrated an exceptional response to the addition of olaparib to chemo-immunotherapy and subsequent olaparib maintenance monotherapy for 12 months. CA 19-9 was maintained at low level for 18 months. Despite the failure of a phase II clinical trial on olaparib in gastric cancer (NCT01063517) to meet its primary endpoint, intriguing findings emerged in the subset of ATM-mutated patients, who exhibited notable improvements in overall survival. Our case underscores the potential clinical utility of olaparib in germline ATM-mutated gastric cancer and emphasizes the need for further exploration through larger clinical trials. Ongoing research and clinical trials are essential for optimizing the use of PARP inhibitors, identifying biomarkers, and advancing personalized treatment strategies for gastric cancer.

Clinical Outcomes for Previously Treated Patients with Advanced Gastric or Gastroesophageal Junction Cancer: A Systematic Literature Review and Meta-Analysis

PURPOSE

Although second-line treatments improve survival compared to best supportive care in patients with advanced gastric cancer with disease progression on first-line therapy, prognosis remains poor. A systematic review and meta-analysis were conducted to quantify the efficacy of second-or-later line systemic therapies in this target population.

METHODS

A systematic literature review (January 1, 2000 to July 6, 2021) of Embase, MEDLINE, and CENTRAL with additional searches of 2019-2021 annual ASCO and ESMO conferences was conducted to identify studies in the target population. A random-effects meta-analysis was performed among studies involving chemotherapies and targeted therapies relevant in treatment guidelines and HTA activities. Outcomes of interest were objective response rate (ORR), overall survival (OS), and progression-free survival (PFS) presented as Kaplan-Meier data. Randomized controlled trials reporting any of the outcomes of interest were included. For OS and PFS, individual patient-level data were reconstructed from published Kaplan-Meier curves.

RESULTS

Forty-four trials were eligible for the analysis. Pooled ORR (42 trials; 77 treatment arms; 7256 participants) was 15.0% (95% confidence interval (CI) 12.7-17.5%). Median OS from the pooled analysis (34 trials; 64 treatment arms; 60,350 person-months) was 7.9 months (95% CI 7.4-8.5). Median PFS from the pooled analysis (32 trials; 61 treatment arms; 28,860 person-months) was 3.5 months (95% CI 3.2-3.7).

CONCLUSION

Our study confirms poor prognosis among patients with advanced gastric cancer, following disease progression on first-line therapy. Despite the approved, recommended, and experimental systemic treatments available, there is still an unmet need for novel interventions for this indication.

Genetic characteristics of platinum-sensitive ovarian clear cell carcinoma

OBJECTIVE

Most ovarian clear cell carcinomas are resistant to platinum-based chemotherapy, while a small subset shows a positive response. The aim of this study was to clarify the clinical, pathological and genetic characteristics of platinum-sensitive ovarian clear cell carcinomas.

METHODS

The study included 53 patients with stage III-IV ovarian clear cell carcinoma who had residual tumours after primary surgery and received platinum-based therapy between 2009 and 2018. A retrospective examination of platinum sensitivity was performed using the criterion of ≥6 months from the last day of first-line platinum therapy until recurrence/progression. Cases determined to be platinum-sensitive were subjected to immunohistochemical staining, genomic analyses using target sequencing (i.e. NCC Oncopanel) and homologous recombination deficiency (myChoice® HRD Plus) assays.

RESULTS

Of the 53 stage III-IV ovarian clear cell carcinoma cases, 11 (21%) were platinum-sensitive. These cases showed better progression-free and overall survival than platinum-resistant cases (hazard ratio = 0.16, P < 0.001). Among the seven sensitive cases whose tumour tissues were available for molecular profiling, five were pure ovarian clear cell carcinoma based on pathological and genetic features, whereas the remaining two cases were re-diagnosed as high-grade serous ovarian carcinoma. The pure ovarian clear cell carcinomas lacked BRCA1 and BRCA2 mutations, consistent with the absence of the homologous recombination deficiency phenotype, whereas two cases (40%) had ATM mutations. By contrast, the two high-grade serous ovarian carcinoma cases had BRCA1 or BRCA2 mutations associated with the homologous recombination deficiency phenotype.

CONCLUSION

The subset of platinum-sensitive ovarian clear cell carcinomas includes a majority with pure ovarian clear cell carcinoma features that lack the homologous recombination deficiency phenotype.

PARP deficiency causes hypersensitivity to Taxol through oxidative stress induced DNA damage

Taxol is an antitumor drug derived from the bark of the Pacific Yew tree that inhibits microtubule disassembly, resulting in cell cycle arrest in late G2 and M phases. Additionally, Taxol increases cellular oxidative stress by generating reactive oxygen species. We hypothesized that the inhibition of specific DNA repair machinery/mechanisms would increase cellular sensitivity to the oxidative stress capacity of Taxol. Initial screening using Chinese hamster ovary (CHO) cell lines demonstrated that base excision repair deficiency, especially PARP deficiency, caused cellular Taxol hypersensitivity. Taxane diterpenes-containing Taxus yunnanensis extract also showed hypertoxicity in PARP deficient cells, which was consistent with other microtubule inhibitors like colcemid, vinblastine, and vincristine. Acute exposure of 50 nM Taxol treatment induced both significant cytotoxicity and M-phase arrest in PARP deficient cells, but caused neither significant cytotoxicity nor late G2-M cell cycle arrest in wild type cells. Acute exposure of 50 nM Taxol treatment induced oxidative stress and DNA damage. The antioxidant Ascorbic acid 2 glucoside partially reduced the cytotoxicity of Taxol in PARP deficient cell lines. Finally, the PARP inhibitor Olaparib increased cytotoxicity of Taxol in wild type CHO cells and two human cancer cell lines. Our study clearly demonstrates that cytotoxicity of Taxol would be enhanced by inhibiting PARP function as an enzyme implicated in DNA repair for oxidative stress.

A Review of Advances in Radiotherapy in the Setting of Esophageal Cancers

Esophageal cancer is the eighth most common cancer worldwide and is the sixth most common cause of cancer-related mortality. The paradigm has shifted to include a multimodality approach with surgery, chemotherapy, targeted therapy (including immunotherapy), and radiation therapy. Advances in radiotherapy through techniques such as intensity modulated radiotherapy and proton beam therapy have allowed for the more dose homogeneity and improved organ sparing. In addition, recent studies of targeted therapies and predictive approaches in patients with locally advanced disease provide clinicians with new approaches to modify multimodality treatment to improve clinical outcomes.

Cysteine depletion sensitizes prostate cancer cells to agents that enhance DNA damage and to immune checkpoint inhibition

BACKGROUND

Prostate Cancer (PCa) represents one of the most commonly diagnosed neoplasms in men and is associated with significant morbidity and mortality. Therapy resistance and significant side effects of current treatment strategies indicate the need for more effective agents to treat both androgen-dependent and androgen-independent PCa. In earlier studies, we demonstrated that depletion of L-cysteine/cystine with an engineered human enzyme, Cyst(e)inase, increased intracellular ROS levels and inhibited PCa growth in vitro and in vivo. The current study was conducted to further explore the mechanisms and potential combinatorial approaches with Cyst(e)inase for treatment of PCa.

METHODS

DNA single strand breaks and clustered oxidative DNA damage were evaluated by alkaline comet assay and pulsed field gel electrophoresis, respectively. Neutral comet assay and immunofluorescence staining was used to measure DNA double strand breaks. Cell survival and reactive oxygen species level were measured by crystal violet assay and DCFDA staining, respectively. Western blot was used to determine protein expression. FACS analyses were preformed for immune cell phenotyping. Allograft and xenograft tumor models were used for assessing effects on tumor growth.

RESULTS

PCa cells treated with Cyst(e)inase lead to DNA single and double strand breaks resulted from clustered oxidative DNA damage (SSBs and DSBs). Cyst(e)inase in combination with Auranofin, a thioredoxin reductase inhibitor, further increased intracellular ROS and DNA DSBs and synergistically inhibited PCa cell growth in vitro and in vivo. A combination of Cyst(e)inase with a PARP inhibitor (Olaparib) also increased DNA DSBs and synergistically inhibited PCa cell growth in vitro and in vivo without additional ROS induction. Knockdown of BRCA2 in PCa cells increased DSBs and enhanced sensitivity to Cyst(e)inase. Finally, Cyst(e)inase treatment altered tumor immune infiltrates and PD-L1 expression and sensitized PCa cells to anti-PD-L1 treatment.

CONCLUSIONS

The current results demonstrate the importance of oxidative DNA damage either alone or in combination for Cyst(e)inase-induced anticancer activity. Furthermore, cysteine/cystine depletion alters the tumor immune landscape favoring enhanced immune checkpoint inhibition targeting PD-L1. Thus, combinatorial approaches with Cyst(e)inase could lead to novel therapeutic strategies for PCa.

Radiotherapy and olaparib in combination for carcinoma of the oesophagus: A phase I study

Background and purpose

Radical concurrent chemoradiotherapy (CRT) for oesophageal cancer is associated with significant morbidity and is unsuitable for some patients. Olaparib, an inhibitor of the DNA repair enzyme poly-(ADP)-ribose polymerase (PARP) has radiosensitising properties and may be better tolerated than chemotherapy.

Materials and methods

We performed a phase 1 study of olaparib with radiotherapy (RT) in oesophageal cancer patients unsuitable for conventional CRT to determine its maximum tolerated dose (MTD) in this setting.

Results

Eight patients were recruited. One of 5 patients receiving olaparib 50 mg twice daily and two of 3 receiving 100 mg twice daily experienced dose limiting toxicity (DLT).

Conclusions

Olaparib 100 mg twice daily exceeded the MTD in combination with RT in these patients. 50 mg twice daily may be the MTD but this cannot be stated with certainty as the study closed before full recruitment.

Incidence and Prognostic Impact of Deleterious Germline Mutations in Primary Advanced Ovarian Carcinoma Patients

Data on deleterious variants in genes other than BRCA1/2 remain limited. A retrospective cohort study was performed, including primary OC cases with TruRisk^® germline gene panel testing between 2011 and 2020. Patients with testing after relapse were excluded. The cohort was divided into three groups: (A) no mutations, (B) deleterious BRCA1/2 mutations, and (C) deleterious mutations in other genes. A total of 702 patients met the inclusion criteria. Of these 17.4% (n = 122) showed BRCA1/2 mutations and a further 6.0% (n = 42) in other genes. Three-year overall survival (OS) of the entire cohort was significantly longer in patients with germline mutations (85%/82.8% for cohort B/C vs. 70.2% for cohort A, p < 0.001) and 3-year progression-free survival (PFS) only for cohort B (58.1% vs. 36.9%/41.6% in cohort A/C, p = 0.002). In multivariate analysis for the subgroup of advanced-stages of high-grade serous OC, both cohorts B/C were found to be independent factors for significantly better outcome, cohort C for OS (HR 0.46; 95% CI 0.25-0.84), and cohort B for both OS and PFS (HR 0.40; 95% CI 0.27-0.61 and HR 0.49; 95% CI 0.37-0.66, respectively). Germline mutations were detected in a quarter of OC patients, and a quarter of those in genes other than BRCA1/2. Germline mutations demonstrate in our cohort a prognostic factor and predict better prognosis for OC patients.

Detection of a Novel MSI2-C17orf64 Transcript in a Patient with Aggressive Adenocarcinoma of the Gastroesophageal Junction: A Case Report

Adenocarcinoma of the esophagus (EAC) and gastroesophageal junction (GEJ-AC) is associated with poor prognosis, treatment resistance and limited systemic therapeutic options. To deeply understand the genomic landscape of this cancer type, and potentially identify a therapeutic target in a neoadjuvant chemotherapy non-responder 48-year-old man, we adopted a multi-omic approach. We simultaneously evaluated gene rearrangements, mutations, copy number status, microsatellite instability and tumor mutation burden. The patient displayed pathogenic mutations of the TP53 and ATM genes and variants of uncertain significance of three kinases genes (ERBB3, CSNK1A1 and RPS6KB2), along with FGFR2 and KRAS high copy number amplification. Interestingly, transcriptomic analysis revealed the Musashi-2 (MSI2)-C17orf64 fusion that has never been reported before. Rearrangements of the RNA-binding protein MSI2 with a number of partner genes have been described across solid and hematological tumors. MSI2 regulates several biological processes involved in cancer initiation, development and resistance to treatment, and deserves further investigation as a potential therapeutic target. In conclusion, our extensive genomic characterization of a gastroesophageal tumor refractory to all therapeutic approaches led to the discovery of the MSI2-C17orf64 fusion. The results underlie the importance of deep molecular analyses enabling the identification of novel patient-specific markers to be monitored during therapy or even targeted at disease evolution.

Perioperative Tailored Treatments for Gastric Cancer: Times Are Changing

Resectable gastric or gastroesophageal (G/GEJ) cancer is a heterogeneous disease with no defined molecularly based treatment strategy. Unfortunately, nearly half of patients experience disease recurrence despite standard treatments (neoadjuvant and/or adjuvant chemotherapy/chemoradiotherapy and surgery). In this review, we summarize the evidence of potential tailored approaches in perioperative treatment of G/GEJ cancer, with a special focus on patients with human epidermal growth factor receptor-2(HER2)-positive and microsatellite instability-high (MSI-H) tumors. In patients with resectable MSI-H G/GEJ adenocarcinoma, the ongoing INFINITY trial introduces the concept of non-operative management for patients with complete clinical-pathological-molecular response, and this could be a novel and potential practice changing strategy. Other pathways involving vascular endothelial growth factor receptor (VEGFR), fibroblast growth factor receptor (FGFR), claudin18 isoform 2 (CLDN18.2), and DNA damage repair proteins are also described, with limited evidence until now. Although tailored therapy appears to be a promising strategy for resectable G/GEJ cancer, there are several methodological issues to address: inadequate sample size for pivotal trials, underestimation of subgroup effects, and choice of primary endpoint (tumor-centered vs. patient-centered endpoints). A better optimization of G/GEJ cancer treatment allows maximizing patient outcomes. In the perioperative phase, although caution is mandatory, times are changing and tailored strategies could introduce new treatment concepts. Overall, MSI-H G/GEJ cancer patients possess the characteristics to be the subgroup that could receive the most benefit from a tailored approach.

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

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

Current molecular biomarkers evaluation in gastric/gastroesophageal junction adenocarcinoma: pathologist does matter

The comprehensive molecular characterization of gastric and gastroesophageal junction adenocarcinomas has led to the improvement of targeted and more effective treatments. As a result, several biomarkers have been introduced into clinical practice and the implementation of innovative diagnostic tools is under study. Such assessments are mainly based on the evaluation of limited biopsy material in clinical practice. In this setting, the pathologist represents a key player in the selection of patients facilitating precision medicine approaches.

Molecular-Targeted Therapy for Tumor-Agnostic Mutations in Acute Myeloid Leukemia

Comprehensive genomic profiling examinations (CGPs) have recently been developed, and a variety of tumor-agnostic mutations have been detected, leading to the development of new molecular-targetable therapies across solid tumors. In addition, the elucidation of hereditary tumors, such as breast and ovarian cancer, has pioneered a new age marked by the development of new treatments and lifetime management strategies required for patients with potential or presented hereditary cancers. In acute myeloid leukemia (AML), however, few tumor-agnostic or hereditary mutations have been the focus of investigation, with associated molecular-targeted therapies remaining poorly developed. We focused on representative tumor-agnostic mutations such as the TP53, KIT, KRAS, BRCA1, ATM, JAK2, NTRK3, FGFR3 and EGFR genes, referring to a CGP study conducted in Japan, and we considered the possibility of developing molecular-targeted therapies for AML with tumor-agnostic mutations. We summarized the frequency, the prognosis, the structure and the function of these mutations as well as the current treatment strategies in solid tumors, revealed the genetical relationships between solid tumors and AML and developed tumor-agnostic molecular-targeted therapies and lifetime management strategies in AML.

Significance of monocyte infiltration in patients with gastric cancer: A combined study based on single cell sequencing and TCGA

BACKGROUND

Gastric cancer is still one of the most lethal tumor diseases in the world. Despite some improvements, the prognosis of patients with gastric cancer is still not accurately predicted.

METHODS

Based on single cell sequencing data, we conducted a detailed analysis of gastric cancer patients and normal tissues to determine the role of monocytes in the progression of gastric cancer. WCGA facilitated our search for Grade-related genes in TCGA. Then, according to the marker genes and cell differentiation genes of monocytes, we determined the cancer-promoting genes of monocytes. Based on LASSO regression, we established a prognostic model using TCGA database. The accuracy of the model was verified by PCA, ROC curve, survival analysis and prognostic analysis. Finally, we evaluated the significance of the model in clinical diagnosis and treatment by observing drug sensitivity, immune microenvironment and immune checkpoint expression in patients with different risk groups.

RESULTS

Monocytes were poorly differentiated in tumor microenvironment. It mainly played a role in promoting cancer in two ways. One was to promote tumor progression indirectly by interacting with other tumor stromal cells. The other was to directly connect with tumor cells through the MIF and TNF pathway to play a tumor-promoting role. The former was more important in these two ways. A total of 292 monocyte tumor-promoting genes were obtained, and 12 genes were finally included in the construction of the prognosis model. A variety of validation methods showed that our model had an accurate prediction ability. Drug sensitivity analysis could provide guidance for clinical medication of patients. The results of immune microenvironment and immune checkpoint also indicated the reasons for poor prognosis of high-risk patients.

CONCLUSION

In conclusion, we provided a 12-gene risk score formula and nomogram for gastric cancer patients to assist clinical drug therapy and prognosis prediction. This model had good accuracy and clinical significance.

Recent Trends and Advancements in the Diagnosis and Management of Gastric Cancer

Gastric cancer is an enigmatic malignancy that has recently been shown to be increasing in incidence globally. There has been recent progress in emerging technologies for the diagnosis and treatment of the disease. Improvements in non-invasive diagnostic techniques with serological tests and biomarkers have led to decreased use of invasive procedures such as endoscopy. A multidisciplinary approach is used to treat gastric cancer, with recent significant advancements in systemic therapies used in combination with cytotoxic chemotherapies. New therapeutic targets have been identified and clinical trials are taking place to assess their efficacy and safety. In this review, we provide an overview of the current and emerging treatment strategies and diagnostic techniques for gastric cancer.

Adénocarcinome œsogastrique – nouvelles cibles thérapeutiques

The median overall survival of metastatic esophagogastric adenocarcinoma is approximately twelve months. In fifteen years, major breakthrough have been the targeting of HER2 overexpression and more recently immunotherapy in patients with CPS≥5. Recent advances in molecular biology have identified some molecular alterations in esophageal adenocarcinoma, interesting to target. FGFR2 is overexpressed in one third of patients, and its targeting with a specific monoclonal antibody bemarituzumab showed a significant improvement in survival. Claudin 18.2 (CLDN 18.2) is overexpressed in at least a third of esophagogastric adenocarcinomas. The combination of zolbetuximab and chemotherapy provides a survival benefit, correlated with the intensity of CLDN 18.2 expression. The potential interest of targeting other pathways is under investigation in several trials with some encouraging preliminary data, and early trials in these indications, justifying considering large molecular screening in patients who might be candidate for early phase trial. Finally, with the recent advent of immunotherapy, one of the future challenges will be to optimize it through combination strategies with targeted therapies. The combination of anti-angiogenic and immunotherapy seems promising in gastric cancer.

Overlapping gene dependencies for PARP inhibitors and carboplatin response identified by functional CRISPR-Cas9 screening in ovarian cancer

PARP inhibitors (PARPi) have revolutionized the therapeutic landscape of epithelial ovarian cancer (EOC) treatment with outstanding benefits in regard to progression-free survival, especially in patients either carrying BRCA1/2 mutations or harboring defects in the homologous recombination repair system. Yet, it remains uncertain which PARPi to apply and how to predict responders when platinum sensitivity is unknown. To shed light on the predictive power of genes previously suggested to be associated with PARPi response, we systematically reviewed the literature and identified 79 publications investigating a total of 93 genes. The top candidate genes were further tested using a comprehensive CRISPR-Cas9 mutagenesis screening in combination with olaparib treatment. Therefore, we generated six constitutive Cas9⁺ EOC cell lines and profiled 33 genes in a CRISPR-Cas9 cell competition assay using non-essential (AAVS1) and essential (RPA3 and PCNA) genes for cell fitness as negative and positive controls, respectively. We identified only ATM, MUS81, NBN, BRCA2, and RAD51B as predictive markers for olaparib response. As the major survival benefit of PARPi treatment was reported in platinum-sensitive tumors, we next assessed nine top candidate genes in combination with three PARPi and carboplatin. Interestingly, we observed similar dropout rates in a gene and compound independent manner, supporting the strong correlation of cancer cell response to compounds that rely on DNA repair for their effectiveness. In addition, we report on CDK12 as a common vulnerability for EOC cell survival and proliferation without altering the olaparib response, highlighting its potential as a therapeutic target in EOC.

Small molecule inhibitors targeting the cancers

Compared with traditional therapies, targeted therapy has merits in selectivity, efficacy, and tolerability. Small molecule inhibitors are one of the primary targeted therapies for cancer. Due to their advantages in a wide range of targets, convenient medication, and the ability to penetrate into the central nervous system, many efforts have been devoted to developing more small molecule inhibitors. To date, 88 small molecule inhibitors have been approved by the United States Food and Drug Administration to treat cancers. Despite remarkable progress, small molecule inhibitors in cancer treatment still face many obstacles, such as low response rate, short duration of response, toxicity, biomarkers, and resistance. To better promote the development of small molecule inhibitors targeting cancers, we comprehensively reviewed small molecule inhibitors involved in all the approved agents and pivotal drug candidates in clinical trials arranged by the signaling pathways and the classification of small molecule inhibitors. We discussed lessons learned from the development of these agents, the proper strategies to overcome resistance arising from different mechanisms, and combination therapies concerned with small molecule inhibitors. Through our review, we hoped to provide insights and perspectives for the research and development of small molecule inhibitors in cancer treatment.

Blockades of effector T cell senescence and exhaustion synergistically enhance antitumor immunity and immunotherapy

BACKGROUND

Current immunotherapies still have limited successful rates among cancers. It is now recognized that T cell functional state in the tumor microenvironment (TME) is a key determinant for effective antitumor immunity and immunotherapy. In addition to exhaustion, cellular senescence in tumor-infiltrating T cells (TILs) has recently been identified as an important T cell dysfunctional state induced by various malignant tumors. Therefore, a better understanding of the molecular mechanism responsible for T cell senescence in the TME and development of novel strategies to prevent effector T cell senescence are urgently needed for cancer immunotherapy.

METHODS

Senescent T cell populations in the TMEs in mouse lung cancer, breast cancer, and melanoma tumor models were evaluated. Furthermore, T cell senescence induced by mouse tumor and regulatory T (Treg) cells in vitro was determined with multiple markers and assays, including real-time PCR, flow cytometry, and histochemistry staining. Loss-of-function strategies with pharmacological inhibitors and the knockout mouse model were used to identify the potential molecules and pathways involved in T cell senescence. In addition, melanoma mouse tumor immunotherapy models were performed to explore the synergistical efficacy of antitumor immunity via prevention of tumor-specific T cell senescence combined with anti-programmed death-ligand 1 (anti-PD-L1) checkpoint blockade therapy.

RESULTS

We report that both mouse malignant tumor cells and Treg cells can induce responder T cell senescence, similar as shown in human Treg and tumor cells. Accumulated senescent T cells also exist in the TME in tumor models of lung cancer, breast cancer and melanoma. Induction of ataxia-telangiectasia mutated protein (ATM)-associated DNA damage is the cause for T cell senescence induced by both mouse tumor cells and Treg cells, which is also regulated by mitogen-activated protein kinase (MAPK) signaling. Furthermore, blockages of ATM-associated DNA damage and/or MAPK signaling pathways in T cells can prevent T cell senescence mediated by tumor cells and Treg cells in vitro and enhance antitumor immunity and immunotherapy in vivo in adoptive transfer T cell therapy melanoma models. Importantly, prevention of tumor-specific T cell senescence via ATM and/or MAPK signaling inhibition combined with anti-PD-L1 checkpoint blockade can synergistically enhance antitumor immunity and immunotherapy in vivo.

CONCLUSIONS

These studies prove the novel concept that targeting both effector T cell senescence and exhaustion is an effective strategy and can synergistically enhance cancer immunotherapy.

Molecular Pathology of Gastric Cancer

Gastric cancer (GC) is one of the most common lethal malignant neoplasms worldwide, with limited treatment options for both locally advanced and/or metastatic conditions, resulting in a dismal prognosis. Although the widely used morphological classifications may be helpful for endoscopic or surgical treatment choices, they are still insufficient to guide precise and/or personalized therapy for individual patients. Recent advances in genomic technology and high-throughput analysis may improve the understanding of molecular pathways associated with GC pathogenesis and aid in the classification of GC at the molecular level. Advances in next-generation sequencing have enabled the identification of several genetic alterations through single experiments. Thus, understanding the driver alterations involved in gastric carcinogenesis has become increasingly important because it can aid in the discovery of potential biomarkers and therapeutic targets. In this article, we review the molecular classifications of GC, focusing on The Cancer Genome Atlas (TCGA) classification. We further describe the currently available biomarker-targeted therapies and potential biomarker-guided therapies. This review will help clinicians by providing an inclusive understanding of the molecular pathology of GC and may assist in selecting the best treatment approaches for patients with GC.

Successes and failures of angiogenesis blockade in gastric and gastro-esophageal junction adenocarcinoma

Gastric and gastro-esophageal junction adenocarcinoma (GEA) remains a considerable major public health problem worldwide, being the fifth most common cancer with a fatality-to-case ratio that stands still at 70%. Angiogenesis, which is a well-established cancer hallmark, exerts a fundamental role in cancer initiation and progression and its targeting has been actively pursued as a promising therapeutic strategy in GEA. A wealth of clinical trials has been conducted, investigating anti-angiogenic agents including VEGF-directed monoclonal antibodies, small molecules tyrosine kinase inhibitors and VEGF-Trap agents both in the resectable and advanced setting, reporting controversial results. While phase III randomized trials testing the anti-VEGFR-2 antibody Ramucirumab and the selective VEGFR-2 tyrosine kinase inhibitor Apatinib demonstrated a significant survival benefit in later lines, the shift of angiogenesis inhibitors in the perioperative and first-line setting failed to improve patients’ outcome in GEAs. The molecular landscape of disease, together with novel combinatorial strategies and biomarker-selected approaches are under investigation as key elements to the success of angiogenesis blockade in GEA. In this article, we critically review the existing literature on the biological rationale and clinical development of antiangiogenic agents in GEA, discussing major achievements, limitations and future developments, aiming at fully realizing the potential of this therapeutic approach.

Functions of Breast Cancer Predisposition Genes: Implications for Clinical Management

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

Molecular pathogenesis and emerging targets of gastric adenocarcinoma

Gastric adenocarcinoma (GC) is a devastating disease and is the third leading cause of cancer deaths worldwide. This heterogeneous disease has several different classification systems that consider histological appearance and genomic alterations. Understanding the etiology of GC, including infection, hereditary conditions, and environmental factors, is of particular importance and is discussed in this review. To improve survival in GC, we also must improve our therapeutic strategies. Here, we discuss new targets that warrant further exploration.

Homologous Recombination Repair in Biliary Tract Cancers: A Prime Target for PARP Inhibition?

Biliary tract cancers (BTCs) are a heterogeneous group of malignancies that make up ~7% of all gastrointestinal tumors. It is notably aggressive and difficult to treat; in fact, >70% of patients with BTC are diagnosed at an advanced, unresectable stage and are not amenable to curative therapy. For these patients, chemotherapy has been the mainstay treatment, providing an inadequate overall survival of less than one year. Despite the boom in targeted therapies over the past decade, only a few targeted agents have been approved in BTCs (i.e., IDH1 and FGFR inhibitors), perhaps in part due to its relatively low incidence. This review will explore current data on PARP inhibitors (PARPi) used in homologous recombination deficiency (HRD), particularly with respect to BTCs. Greater than 28% of BTC cases harbor mutations in genes involved in homologous recombination repair (HRR). We will summarize the mechanisms for PARPi and its role in synthetic lethality and describe select genes in the HRR pathway contributing to HRD. We will provide our rationale for expanding patient eligibility for PARPi use based on literature and anecdotal evidence pertaining to mutations in HRR genes, such as RAD51C, and the potential use of reliable surrogate markers of HRD.

First phase 1 clinical study of olaparib in pediatric patients with refractory solid tumors

BACKGROUND

The survival of patients with high-risk, refractory, relapsed, or metastatic solid tumors remains dismal. A poly(ADP-ribose) polymerase (PARP) inhibitor could be effective for the treatment of pediatric solid tumors with defective homologous recombination.

METHODS

This open-label, multicenter phase 1 clinical trial evaluated the safety, tolerability, and efficacy of olaparib, a PARP inhibitor, in pediatric patients with refractory solid tumors to recommend a dose for Phase 2 trials. Olaparib (62.5, 125, and 187.5 mg/m² twice daily) was administered orally every day (1 cycle = 28 days) using a standard 3 + 3 dose-escalation design. Patients aged 3-18 years with recurrent pediatric solid tumors were eligible. Pharmacokinetic and pharmacodynamic analyses were performed.

RESULTS

Fifteen patients were enrolled and received olaparib monotherapy, which was well tolerated. The recommended phase 2 dose for daily administration was 187.5 mg/m² twice daily. Pharmacokinetics were dose proportional. The area under the concentration-time curve from 0 to 12 h and the peak plasma concentration for 187.5 mg/m² twice daily in children were comparable to previous data obtained in a 200-mg, twice-daily cohort and lower than those in the 300-mg twice-daily cohort in adults. Pharmacodynamic studies demonstrated substantial inhibition of PARP activity. Two partial responses were observed in patients with Wilms tumor and neuroblastoma.

CONCLUSIONS

This report is the first clinical trial to describe the use of a PARP inhibitor as monotherapy in children. Olaparib was well tolerated, with preliminary antitumor responses observed in DNA damage response-defective pediatric tumors.

LAY SUMMARY

This Phase 1 trial evaluated the efficacy and safety of olaparib in patients with refractory childhood solid tumors. Olaparib was well tolerated, achieving objective response in 2/15 patients. The DNA damage response was attenuated in nearly one-half of advanced neuroblastoma patients, demonstrating the utility of the PARP inhibitor. The results support further investigation of olaparib as a new treatment for DNA damage-response or repair-defective pediatric cancers.

Targeting the DNA Damage Response Pathway as a Novel Therapeutic Strategy in Colorectal Cancer

Simple Summary

Defective DNA damage response (DDR) is a hallmark of cancer leading to genomic instability. Up to 15–20% of colorectal cancers carry alterations in DDR. However, the role of DDR alterations as a prognostic factor and as a therapeutic target must be elucidated. To date, disappointing results have been obtained in different clinical trials mainly due to poor molecular selection of patients. Several challenges must be overcome before these compounds may have an impact on colorectal cancer. For instance, although some preclinical evidence showed the vulnerability of a subset of CRCs to PARP inhibitors, no specific clinical or molecular biomarkers have been validated to select patients. Moreover, different DDR alterations may not equally confer platinum sensitivity in CRC patients. Further efforts are needed in both preclinical and clinical settings to exploit DDR alterations as therapeutic targets and to eventually discover PARP or other DDR inhibitors (e.g., Wee1) with clinical benefit on colorectal cancer patients.

Abstract

Major advances have been made in CRC treatment in recent years, especially in molecularly driven therapies and immunotherapy. Despite this, a large number of advanced colorectal cancer patients do not benefit from these treatments and their prognosis remains poor. The landscape of DNA damage response (DDR) alterations is emerging as a novel target for treatment in different cancer types. PARP inhibitors have been approved for the treatment of ovarian, breast, pancreatic, and prostate cancers carrying deleterious BRCA1/2 pathogenic variants or homologous recombination repair (HRR) deficiency (HRD). Recent research reported on the emerging role of HRD in CRC and showed that alterations in these genes, either germline or somatic, are carried by up to 15–20% of CRCs. However, the role of HRD is still widely unknown, and few data about their clinical impact are available, especially in CRC patients. In this review, we report preclinical and clinical data currently available on DDR inhibitors in CRC. We also emphasize the predictive role of DDR mutations in response to platinum-based chemotherapy and the potential clinical role of DDR inhibitors. More preclinical and clinical trials are required to better understand the impact of DDR alterations in CRC patients and the therapeutic opportunities with novel DDR inhibitors.

PARP Inhibitor Applicability: Detailed Assays for Homologous Recombination Repair Pathway Components

Poly(ADP-ribose) polymerase inhibitors (PARPi) have been in clinical use since 2014 for certain patients with germline BRCA1/2 mutations, but as evidence and approvals for their use in a wider range of patients grow, the question of how best to identify patients who would benefit from PARPi becomes ever more complex. Here, we discuss the development and current state of approved selection testing for PARPi therapy and the ongoing efforts to define a broader range of homologous recombination repair deficiencies that are susceptible to PARP inhibition.

The role of PARP inhibitors in gastrointestinal cancers

The use of BReast CAncer (BRCA) mutations as biomarkers for sensitivity to DNA damage response (DDR) targeted drugs and platinum agents is well documented in breast and gynaecological cancers. More recently the successful use DDR targeted therapies including poly (ADP-ribose) polymerases (PARP) inhibitors has been shown to extend to other germline and somatic deficiencies within the homologous recombination (HR) pathway^1-3. Gastrointestinal (GI) cancers are lagging behind other tumour types when it comes to personalising treatment with targeted therapies. Current methods of identifying PARP-inhibitor sensitivity in gastrointestinal cancers are based on analogies from other cancer types despite there being a lack of uniformity in determining HR status between tumour types. There is an urgent clinical need to better understand the treatment implications of DDR alterations in gastrointestinal cancers. We have reviewed PARP-inhibitor use in pancreatic, gastroesophageal, hepatobiliary and colorectal cancers and explored HRD as a biomarker for sensitivity to PARP-inhibitors.

Molecular mechanism of therapeutic approaches for human gastric cancer stem cells

Gastric cancer (GC) is a primary cause of cancer-related mortality worldwide, and even after therapeutic gastrectomy, survival rates remain poor. The presence of gastric cancer stem cells (GCSCs) is thought to be the major reason for resistance to anticancer treatment (chemotherapy or radiotherapy), and for the development of tumor recurrence, epithelial–mesenchymal transition, and metastases. Additionally, GCSCs have the capacity for self-renewal, differentiation, and tumor initiation. They also synthesize antiapoptotic factors, demonstrate higher performance of drug efflux pumps, and display cell plasticity abilities. Moreover, the tumor microenvironment (TME; tumor niche) that surrounds GCSCs contains secreted growth factors and supports angiogenesis and is thus responsible for the maintenance of the growing tumor. However, the genesis of GCSCs is unclear and exploration of the source of GCSCs is essential. In this review, we provide up-to-date information about GCSC-surface/intracellular markers and GCSC-mediated pathways and their role in tumor development. This information will support improved diagnosis, novel therapeutic approaches, and better prognosis using GCSC-targeting agents as a potentially effective treatment choice following surgical resection or in combination with chemotherapy and radiotherapy. To date, most anti-GCSC blockers when used alone have been reported as unsatisfactory anticancer agents. However, when used in combination with adjuvant therapy, treatment can improve. By providing insights into the molecular mechanisms of GCSCs associated with tumors in GC, the aim is to optimize anti-GCSCs molecular approaches for GC therapy in combination with chemotherapy, radiotherapy, or other adjuvant treatment.

Genetic Syndromes Associated with Gastric Cancer

Although environmental factors such as Helicobacter pylori, tobacco, and diet are major contributors to the development of gastric cancer (GC) worldwide, it is estimated that up to 5% to 10% of GC cases are due to an underlying hereditary susceptibility caused by germline pathogenic variants. Hereditary diffuse gastric cancer (HDGC) caused by germline pathogenic variants in the CDH1 gene is the principal familial GC syndrome. However, other well-established hereditary gastrointestinal syndromes have been associated with an increased risk of GC. In this review, we will discuss the latest insights and advances in our understanding of GC associated with Lynch syndrome (LS), familial adenomatous polyposis (FAP), gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS), Li-Fraumeni syndrome (LFS), Peutz-Jeghers syndrome (PJS), and juvenile polyposis syndrome (JPS). We will also discuss the emergence of new associations of the homologous recombination pathway genes (BRCA1, BRCA2) with GC.

PARP mediated DNA damage response, genomic stability and immune responses

Poly (ADP-ribose) polymerase (PARP) enzymes, especially PARP1, play important roles in the DNA damage response and in the maintenance of genome stability, which makes PARPis a classic synthetic lethal therapy for BRCA-deficient tumors. Conventional mechanisms suggest that PARPis exert their effects via catalytic inhibition and PARP-DNA trapping. Recently, PARP1 has been found to play a role in the immune modulation of tumors. The blockade of PARP1 is able to induce innate immunity through a series of molecular mechanisms, thus allowing the prediction of the feasibility of PARPis combined with immune agents in the treatment of tumors. PARPis combined with immunomodulators may have a stronger tumor suppressive effect on inhibiting tumor growth and blocking immune escape. This article is protected by copyright. All rights reserved.

Targeting the DNA damage response: PARP inhibitors and new perspectives in the landscape of cancer treatment

Cancer derives from alterations of pathways responsible for cell survival, differentiation and proliferation. Dysfunctions of mechanisms protecting genome integrity can promote oncogenesis but can also be exploited as therapeutic target. Poly-ADP-Ribose-Polymerase (PARP)-inhibitors, the first approved targeted agents able to tackle DNA damage response (DDR), have demonstrated antitumor activity, particularly when homologous recombination impairment is present. Despite the relevant results achieved, a large proportion of patients fail to obtain durable responses. The development of innovative treatments, able to overcome resistance and ensure long-lasting benefit for a wider population is still an unmet need. Moreover, improvement in biomarker assays is necessary to properly identify patients who can benefit from DDR targeting agents. Here we summarize the main DDR pathways, explain the current role of PARP inhibitors in cancer therapy and illustrate new therapeutic strategies targeting the DDR, focusing on the combinations of PARP inhibitors with other agents and on cell-cycle checkpoint inhibitors.

Novel Biomarkers of Gastric Adenocarcinoma: Current Research and Future Perspectives

Simple Summary

Gastric cancer is characterized by poor survival rates despite surgery and chemotherapy. Current research focuses on biomarkers to improve diagnosis and prognosis, and to enable targeted treatment strategies. The aim of our review was to give an overview over the wide range of novel biomarkers in gastric cancer. These biomarkers are targets of a specific treatment, such as antibodies against human epidermal growth factor receptor 2. Other promising biomarkers for targeted therapies that have shown relevance in clinical trials are vascular endothelial growth factor, programmed cell death protein 1, and Claudin 18.2. There is a vast number of biomarkers based on DNA, RNA, and protein expression, as well as detection of circulating tumor cells and the immune tumor microenvironment.

Abstract

Overall survival of gastric cancer remains low, as patients are often diagnosed with advanced stage disease. In this review, we give an overview of current research on biomarkers in gastric cancer and their implementation in treatment strategies. The HER2-targeting trastuzumab is the first molecular targeted agent approved for gastric cancer treatment. Other promising biomarkers for targeted therapies that have shown relevance in clinical trials are VEGF and Claudin 18.2. Expression of MET has been shown to be a negative prognostic factor in gastric cancer. Targeting the PD-1/PD-L1 pathway with immune checkpoint inhibitors has proven efficacy in advanced gastric cancer. Recent technology advances allow the detection of circulating tumor cells that may be used as diagnostic and prognostic indicators and for therapy monitoring in gastric cancer patients. Prognostic molecular subtypes of gastric cancer have been identified using genomic data. In addition, transcriptome profiling has allowed a comprehensive characterization of the immune and stromal microenvironment in gastric cancer and development of novel risk scores. These prognostic and predictive markers highlight the rapidly evolving field of research in gastric cancer, promising improved treatment stratification and identification of molecular targets for individualized treatment in gastric cancer.

Association of Homologous Recombination-DNA Damage Response Gene Mutations with Immune Biomarkers in Gastroesophageal Cancers

The prevalence of homologous recombination-DNA damage response (HR-DDR) genetic alterations is of therapeutic interest in gastroesophageal cancers. This study is a comprehensive assessment of HR-DDR mutation prevalence across gastroesophageal adenocarcinomas and squamous cell carcinomas. Here we investigate the association of HR-DDR mutations with known predictors for immune-checkpoint inhibition [deficiency in mismatch-repair (dMMRP), tumor mutational burden (TMB), and programmed death ligand 1 (PD-L1)]. We confirmed HR-DDR mutations are present in a subset of gastroesophageal adenocarcinomas (23%) and gastroesophageal squamous cell carcinomas (20%). Biomarker expression of dMMRP (18% vs. 1%) and TMB-high with a cutoff of ≥10 mt/MB (27% vs. 9%) was significantly more prevalent in the DDR-mutated cohort compared with the non-DDR-mutated cohort. Mean combined positive score for PD-L1 in the total adenocarcinoma cohort was significantly higher in the DDR-mutated cohort compared with the non-DDR-mutated cohort (10.1 vs. 5.8). We demonstrated that alterations in ARID1A, BRCA2, PTEN, and ATM are correlated with dMMRP, TMB-high, and increased PD-L1 expression in gastroesophageal adenocarcinomas. Our findings show that a subset of gastroesophageal tumors harbor HR-DDR mutations correlated with established immune biomarkers. By better understanding the relationship between HR-DDR mutations and immune biomarkers, we may be able to develop better immunotherapy combination strategies to target these tumors.

Risk of fatigue with PARP inhibitors in cancer patients: a systematic review and meta-analysis of 29 phase II/III randomized controlled trials

Fatigue was a frequently reported adverse event associated with the use of PARP inhibitors. We performed a systematic review and meta-analysis to fully investigate the fatigue of PARP inhibitors in cancer patients. Databases were searched for randomized controlled trials (RCTs) treated with PARP inhibitors till July 2020. Twenty-nine RCTs and 9479 patients were included. This meta-analysis suggests that the use of PARP inhibitors significantly increase the risk of developing all-grade (RR, 1.25; 95%CI, 1.20-1.31; p < 0.00001; I2 = 48%) and high-grade fatigue (RR, 1.92; 95%CI, 1.51-2.45; p < 0.00001; I2 = 11%). Veliparib was associated with a relatively lower risk of fatigue. Patients with ovarian cancer tend to be associated with a higher risk of fatigue than those with non-ovarian cancer. Longer duration of therapy was associated with a higher risk of all-grade fatigue. Patients receiving PARP inhibitor monotherapy tends to be associated with a higher risk of all-grade fatigue than those receiving combination treatment.

Targeting BRCA and DNA Damage Repair Genes in GI Cancers: Pathophysiology and Clinical Perspectives

Mutated germline alleles in the DNA damage repair (DDR) genes “breast cancer gene 1” (BRCA1) and BRCA2 have originally been identified as major susceptibility genes in breast and ovarian cancers. With the establishment and approval of more cost-effective gene sequencing methods, germline and somatic BRCA mutations have been detected in several cancers. Since the approval of poly (ADP)-ribose polymerase inhibitors (PARPi) for BRCA-mutated cancers, BRCA mutations gained rising therapeutic implications. The impact and significance of BRCA mutations have been evaluated extensively in the last decades. Moreover, other genes involved in the DDR pathway, such as ATM, ATR, or CHK1, have emerged as potential new treatment targets, as inhibitors of these proteins are currently under clinical investigation. This review gives a concise overview on the emerging clinical implications of mutations in the DDR genes in gastrointestinal cancers with a focus on BRCA mutations.

Molecular Targets for Gastric Cancer Treatment and Future Perspectives from a Clinical and Translational Point of View

Gastric cancer is a leading cause of cancer death worldwide. Systemic treatment comprising chemotherapy and targeted therapy is the standard of care in advanced/metastatic gastric cancer. Comprehensive molecular characterization of gastric adenocarcinomas by the TCGA Consortium and ACRG has resulted in the definition of distinct molecular subtypes. These efforts have in parallel built a basis for the development of novel molecularly stratified treatment approaches. Based on this molecular characterization, an increasing number of specific genomic alterations can potentially serve as treatment targets. Consequently, the development of promising compounds is ongoing. In this review, key molecular alterations in gastric and gastroesophageal junction cancers will be addressed. Finally, the current status of the translation of targeted therapy towards clinical applications will be reviewed.

Toward a Treatment Sequencing Strategy: A Systematic Review of Treatment Regimens in Advanced Gastric Cancer/Gastroesophageal Junction Adenocarcinoma

BACKGROUND

Platinum and fluoropyrimidine combinations typically comprise first-line (1L) therapy in advanced gastric cancer or gastroesophageal junction adenocarcinoma (G/GEA), although controversy exists regarding the use of 5doublet versus triplet cytotoxic regimens. Historically, second-line (2L) and third-line or later (3L+) therapy has been fragmented. Recent trials have increased the need for optimal treatment sequencing in advanced G/GEA.

MATERIALS AND METHODS

We conducted a systematic search of peer-reviewed manuscripts of randomized clinical trials examining 1L, 2L, and 3L+ therapy for advanced G/GEA published from 2009 through November 19, 2019. When available, overall survival, progression-free survival, time to progression, overall response rate, and toxicity were extracted from each and compared descriptively.

RESULTS

In 1L therapy, chemotherapy triplets demonstrated variable efficacy improvements with invariable increased toxicity compared with platinum/fluoropyrimidine doublets. Currently, the only published report of positive outcomes using biologics in 1L describes adding trastuzumab in HER2-overexpressing advanced G/GEA. In 2L, doublet chemotherapy regimens are not uniformly more efficacious than single-agent taxanes or irinotecan, and ramucirumab has demonstrated improved outcomes both as monotherapy and in combination.

CONCLUSION

For advanced G/GEA, review of trial results from 2009-2019 support 1L therapy with platinum and fluoropyrimidine and sequencing with taxanes or irinotecan in combination with biologics as effective 2L options. Escalating to a triplet may add some efficacy at the expense of added toxicity.

IMPLICATIONS FOR PRACTICE

The rapidly changing treatment landscape for advanced gastric cancer includes increasing options for refractory disease. With multiple first-line platinum-based regimens, identification of those with the best benefit-to-risk ratio may provide guidance on treatment sequencing strategies. This article presents findings from the published literature of randomized controlled trials that included a first-line platinum/fluoropyrimidine combination and, for second-line trials, patients with platinum/fluoropyrimidine-refractory disease. This guiding summary could be a tool for clinicians to identify the optimal first-line regimen(s) followed by a strategy for subsequent regimens.

Playing on the Dark Side: SMYD3 Acts as a Cancer Genome Keeper in Gastrointestinal Malignancies

Simple Summary

The activity of SMYD3 in promoting carcinogenesis is currently under debate. Growing evidence seems to confirm that SMYD3 overexpression correlates with poor prognosis, cancer growth and invasion, especially in gastrointestinal tumors. In this review, we dissect the emerging role played by SMYD3 in the regulation of cell cycle and DNA damage response by promoting homologous recombination (HR) repair and hence cancer cell genomic stability. Considering the crucial role of PARP1 in other DNA repair mechanisms, we also discuss a recently evaluated synthetic lethality approach based on the combined use of SMYD3 and PARP inhibitors. Interestingly, a significant proportion of HR-proficient gastrointestinal tumors expressing high levels of SMYD3 from the PanCanAtlas dataset seem to be eligible for this innovative strategy. This promising approach could be taken advantage of for therapeutic applications of SMYD3 inhibitors in cancer treatment.

Abstract

The SMYD3 methyltransferase has been found overexpressed in several types of cancers of the gastrointestinal (GI) tract. While high levels of SMYD3 have been positively correlated with cancer progression in cellular and advanced mice models, suggesting it as a potential risk and prognosis factor, its activity seems dispensable for autonomous in vitro cancer cell proliferation. Here, we present an in-depth analysis of SMYD3 functional role in the regulation of GI cancer progression. We first describe the oncogenic activity of SMYD3 as a transcriptional activator of genes involved in tumorigenesis, cancer development and transformation and as a co-regulator of key cancer-related pathways. Then, we dissect its role in orchestrating cell cycle regulation and DNA damage response (DDR) to genotoxic stress by promoting homologous recombination (HR) repair, thereby sustaining cancer cell genomic stability and tumor progression. Based on this evidence and on the involvement of PARP1 in other DDR mechanisms, we also outline a synthetic lethality approach consisting of the combined use of SMYD3 and PARP inhibitors, which recently showed promising therapeutic potential in HR-proficient GI tumors expressing high levels of SMYD3. Overall, these findings identify SMYD3 as a promising target for drug discovery.

Homologous Recombination Deficiency: Cancer Predispositions and Treatment Implications

Homologous recombination (HR) is a highly accurate DNA repair mechanism. Several HR genes are established cancer susceptibility genes with clinically actionable pathogenic variants (PVs). Classically, BRCA1 and BRCA2 germline PVs are associated with significant breast and ovarian cancer risks. Patients with BRCA1 or BRCA2 PVs display worse clinical outcomes but respond better to platinum-based chemotherapies and poly-ADP ribose polymerase inhibitors, a trait termed "BRCAness." With the advent of whole-exome sequencing and multigene panels, PVs in other HR genes are increasingly identified among familial cancers. As such, several genes such as PALB2 are reclassified as cancer predisposition genes. But evidence for cancer risks remains unclear for many others. In this review, we will discuss cancer predispositions and treatment implications beyond BRCA1 and BRCA2, with a focus on 24 HR genes: 53BP1, ATM, ATR, ATRIP, BARD1, BLM, BRIP1, DMC1, MRE11A, NBN, PALB2, RAD50, RAD51, RAD51B, RAD51C, RAD51D, RIF1, RMI1, RMI2, RPA1, TOP3A, TOPBP1, XRCC2, and XRCC3. IMPLICATIONS FOR PRACTICE: This review provides a comprehensive reference for readers to quickly identify potential cancer predisposing homologous recombination (HR) genes, and to generate research questions for genes with inconclusive evidence. This review also evaluates the "BRCAness" of each HR member. Clinicians can refer to these discussions to identify potential candidates for future clinical trials.