The RECQL helicase prevents replication fork collapse during replication stress

Most tumors lack the G1/S phase checkpoint and are insensitive to antigrowth signals. Loss of G1/S control can severely perturb DNA replication as revealed by slow replication fork progression and frequent replication fork stalling. Cancer cells may thus rely on specific pathways that mitigate the deleterious consequences of replication stress. To identify vulnerabilities of cells suffering from replication stress, we performed an shRNA-based genetic screen. We report that the RECQL helicase is specifically essential in replication stress conditions and protects stalled replication forks against MRE11-dependent double strand break (DSB) formation. In line with these findings, knockdown of RECQL in different cancer cells increased the level of DNA DSBs. Thus, RECQL plays a critical role in sustaining DNA synthesis under conditions of replication stress and as such may represent a target for cancer therapy

Niraparib Maintenance Therapy in Patients With Recurrent Ovarian Cancer After a Partial Response to the Last Platinum-Based Chemotherapy in the ENGOT-OV16/NOVA Trial

PURPOSEIn the ENGOT-OV16/NOVA trial (ClinicalTrials.gov identifier: NCT01847274), maintenance therapy with niraparib, a poly(ADP-ribose) polymerase inhibitor, prolonged progression-free survival in patients with platinum-sensitive, recurrent ovarian cancer who had a response to their last platinum-based chemotherapy. The objective of the study was to assess the clinical benefit and patient-reported outcomes in patients who had a partial response (PR) and complete response (CR) to their last platinum-based therapy.PATIENTS AND METHODSA total of 553 patients were enrolled in the trial. Of 203 patients with a germline BRCA mutation (gBRCAmut), 99 had a PR and 104 had a CR to their last platinum-based therapy; of 350 patients without a confirmed gBRCAmut (non?gBRCAmut), 173 had a PR and 177 had a CR. Post hoc analyses were carried out to evaluate safety and the risk of progression in these patients according to gBRCAmut status and response to their last platinum-based therapy. Ovarian cancer?specific symptoms and quality of life were assessed using the Functional Assessment of Cancer Therapy?Ovarian Symptom Index.RESULTSProgression-free survival was improved in patients treated with niraparib compared with placebo in both the gBRCAmut cohort (PR: hazard ratio [HR], 0.24; 95% CI, 0.131 to 0.441; P < .0001; CR: HR, 0.30; 95% CI, 0.160 to 0.546; P < .0001) and the non?gBRCAmut cohort (PR: HR, 0.35; 95% CI, 0.230 to 0.532; P < .0001; CR: HR, 0.58; 95% CI, 0.383 to 0.868; P = .0082). The incidence of any-grade and grade 3 or greater adverse events was manageable. No meaningful differences were observed between niraparib and placebo in PR and CR subgroups with respect to patient-reported outcomes.CONCLUSIONPatients achieved clinical benefit from maintenance treatment with niraparib regardless of response to the last platinum-based therapy

Combining teaching and research: a BIP on geophysical and archaeological prospection of North Frisian medieval settlement patterns

We performed a research-oriented EU Erasmus+ Blended Intensive Program (BIP) with participants from four countries focused on North Frisian terp settlements from Roman Iron Age and medieval times. We show that the complex terp structure and environment can be efficiently prospected using combined magnetic and EMI mapping, and seismic and geoelectric profiling and drilling. We found evidence of multiple terp phases and a harbor at the Roman Iron Age terp of Tofting. In contrast, the medieval terp of Stolthusen is more simply constructed, probably uni-phase. The BIP proved to be a suitable tool for high-level hands-on education adding value to the research conducted in on-going projects

Celastrol-induced degradation of FANCD2 sensitizes pediatric high-grade gliomas to the DNA-crosslinking agent carboplatin

Background: Pediatric high-grade gliomas (pHGG) are the leading cause of cancer-related death during childhood. Due to their diffuse growth characteristics, chemoresistance and location behind the blood-brain barrier (BBB), the prognosis of pHGG has barely improved in the past decades. As such, there is a dire need for new therapies that circumvent those difficulties. Since aberrant expression of DNA damage-response associated Fanconi anemia proteins play a central role in the onset and therapy resistance of many cancers, we here investigated if FANCD2 depletion could sensitize pHGG to additional DNA damage. Methods: We determined the capacity of celastrol, a BBB-penetrable compound that degrades FANCD2, to sensitize glioma cells to the archetypical DNA-crosslinking agent carboplatin in vitro in seven patient-derived pHGG models. In addition, we tested this drug combination in vivo in a patient-derived orthotopic pHGG xenograft model. Underlying mechanisms to drug response were investigated using mRNA expression profiling, western blotting, immunofluorescence, FANCD2 knockdown and DNA fiber assays. Findings: FANCD2 is overexpressed in HGGs and depletion of FANCD2 by celastrol synergises with carboplatin to induce cytotoxicity. Combination therapy prolongs survival of pHGG-bearing mice over monotherapy and control groups in vivo (P<0.05). In addition, our results suggest that celastrol treatment stalls ongoing replication forks, causing sensitivity to DNA-crosslinking in FANCD2-dependent glioma cells. Interpretation: Our results show that depletion of FANCD2 acts as a chemo-sensitizing strategy in pHGG. Combination therapy using celastrol and carboplatin might serve as a clinically relevant strategy for the treatment of pHGG. Funding: This study was funded by a grant from the Children Cancer-Free Foundation (KIKA, project 210). The disclosed funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

WAPL-Dependent Repair of Damaged DNA Replication Forks Underlies Oncogene-Induced Loss of Sister Chromatid Cohesion

Benedict et al. show that in cancer cells the connection between newly synthesized chromatids (cohesion) is often less tight than in normal cells. They show that removal of cohesion in cancer cells is necessary to repair broken DNA replication forks and to sustain tumor cell expansion

SCAI promotes error-free repair of DNA interstrand crosslinks via the Fanconi anemia pathway

DNA interstrand crosslinks (ICLs) are cytotoxic lesions that threaten genome integrity. The Fanconi anemia (FA) pathway orchestrates ICL repair during DNA replication, with ubiquitylated FANCI-FANCD2 (ID2) marking the activation step that triggers incisions on DNA to unhook the ICL. Restoration of intact DNA requires the coordinated actions of polymerase zeta (Pol zeta)-mediated translesion synthesis (TLS) and homologous recombination (HR). While the proteins mediating FA pathway activation have been well characterized, the effectors regulating repair pathway choice to promote error-free ICL resolution remain poorly defined. Here, we uncover an indispensable role of SCAI in ensuring error-free ICL repair upon activation of the FA pathway. We show that SCAI forms a complex with Pol zeta and localizes to ICLs during DNA replication. SCAI-deficient cells are exquisitely sensitive to ICL-inducing drugs and display major hallmarks of FA gene inactivation. In the absence of SCAI, HR-mediated ICL repair is defective, and breaks are instead re-ligated by polymerase theta-dependent microhomology-mediated end-joining, generating deletions spanning the ICL site and radial chromosomes. Our work establishes SCAI as an integral FA pathway component, acting at the interface between TLS and HR to promote error-free ICL repair.Genome Instability and Cance

Quality of life in patients with recurrent ovarian cancer treated with niraparib versus placebo (ENGOT-OV16/NOVA) : results from a double-blind, phase 3, randomised controlled trial

Background: Quality of life (QOL) has become an important complementary endpoint in cancer clinical studies alongside more traditional assessments (eg, tumour response, progression-free survival, overall survival). Niraparib maintenance treatment has been shown to significantly improve progression-free survival in patients with recurrent ovarian cancer. We aimed to assess whether the benefits of extending progression-free survival are offset by treatment-associated toxic effects that affect QOL. Methods: The ENGOT-OV16/NOVA trial was a multicentre, double-blind, phase 3, randomised controlled trial done in 107 study sites in the USA, Canada, Europe, and Israel. Patients with recurrent ovarian cancer who were in response to their last platinum-based chemotherapy were randomly assigned (2:1) to receive either niraparib (300 mg once daily) as a maintenance treatment or placebo. Randomisation was stratified based on time to progression after the penultimate platinum-based regimen, previous use of bevacizumab, and best response (complete or partial) to the last platinum-based regimen with permuted-block randomisation (six in each block) using an interactive web response system. The trial enrolled two independent cohorts on the basis of germline BRCA (gBRCA) mutation status (determined by BRACAnalysis Testing, Myriad Genetics, Salt Lake City, UT, USA). The primary endpoint of the trial was progression-free survival, and has already been reported. In this study, we assessed patient-reported outcomes (PROs) in the intention-to-treat population using the Functional Assessment of Cancer Therapy–Ovarian Symptoms Index (FOSI) and European QOL five-dimension five-level questionnaire (EQ-5D-5L). We collected PROs from trial entry every 8 weeks for the first 14 cycles and every 12 weeks thereafter. If a patient discontinued, we collected PROs at discontinuation and during a postprogression visit 8 weeks (plus or minus 2 weeks) later. We assessed the effect of haematological toxic effects on QOL with disutility analyses of the most common grade 3–4 adverse events (thrombocytopenia, anaemia, and neutropenia) using a mixed model with histology, region, previous treatment, age, planned treatment, and baseline score as covariates. This study is registered with ClinicalTrials.gov, number NCT01847274. Findings: Between Aug 28, 2013, and June 1, 2015, 553 patients were enrolled and randomly assigned to receive niraparib (n=138 in the gBRCAmut cohort, n=234 in the non-gBRCAmut cohort) or placebo (n=65 in the gBRCAmut cohort, n=116 in the non-gBRCAmut cohort). The mean FOSI score at baseline was similar between the two groups (range between 25·0–25·6 in the two groups). Overall QOL scores remained stable during the treatment and preprogression period in the niraparib group; no significant differences were observed between the niraparib and placebo group, and preprogression EQ-5D-5L scores were similar between the two groups in both cohorts (0·838 [0·0097] in the niraparib group vs 0·834 [0·0173] in the placebo group in the gBRCAmut cohort; and 0·833 [0·0077] in the niraparib group vs 0·815 [0·0122] in the placebo group in the non-gBRCAmut cohort). The most common adverse events reported at screening (baseline) were lack of energy (425 [79%]; 97 [18%] reporting severe lack of energy), pain (236 [44%]), and nausea (118 [22%]). All symptoms, except nausea, either remained stable or improved over time in the niraparib group. The most common grade 3 or 4 toxicities observed in the niraparib group were haematological in nature: thrombocytopenia (124 [34%] of 367 patients), anaemia (93 [25%]), and neutropenia (72 [20%]); disutility analyses showed no significant QOL impairment associated with these toxic effects. Interpretation: These PRO data suggest that women who receive niraparib as maintenance treatment for recurrent ovarian cancer after responding to platinum treatment are able to maintain QOL during their treatment when compared with placebo. Funding: TESARO