Methylthioadenosine phosphorylase (MTAP) gene deletions are frequent in human cancers. Loss of MTAP leads to significantly increased cellular levels of methylthioadenosine (MTA), a cellular metabolite and specific inhibitor of the cell-essential enzyme Protein Arginine Methyltransferase-5 (PRMT5). Using a cofactor-directed screening strategy and DNA-encoded libraries, we identify a class of PRMT5 inhibitors that cooperatively inhibit PRMT5 in the presence of MTA. An optimized inhibitor, AM-9934, selectively inhibits PRMT5 in MTAP-deleted cells and in transplanted tumors while sparing MTAP-expressing counterparts, leading to specific suppression of viability in MTAP-deleted cells. Structural studies show that AM-9934 occupies the arginine substrate pocket of MTA-bound PRMT5. This study introduces a broadly applicable method for directed DNA-encoded library screening toward a desired mechanistic outcome and highlights MTA-selective PRMT5 inhibition as an attractive therapeutic strategy with a potentially broad therapeutic index in patients with MTAP-deleted cancers.

Upregulation of DNA-dependent protein kinase (DNA-PK) is associated with poor prognosis and decreased response to DNA-damaging agents across cancer types. A Phase I/IIa study (NCT03907969) investigated the highly potent, selective DNA-PK inhibitor AZD7648 as monotherapy or combined with pegylated liposomal doxorubicin (PLD) in patients with advanced cancer.

Thirty patients received escalating doses of AZD7648 as monotherapy (n = 14), starting at 5 mg QD, or with PLD 40 mg/m2 (n = 16). The primary objective was safety and tolerability.

AZD7648 monotherapy was administered at 5-160 mg BID. The most frequent class of adverse events was gastrointestinal disorders (9/14 patients, 64.3%); one patient (160 mg BID) experienced dose-limiting toxicities (DLTs). No responses to AZD7648 monotherapy were observed. The maximum dose of combination therapy was AZD7648 40 mg QD days 1-7 + PLD every 28 days. 13/16 patients (81.3%) experienced gastrointestinal disorders and 11/16 (68.8%) patients had anaemia. Three patients experienced DLTs (two at AZD7648 20 mg QD 7 days + PLD; one at AZD7648 30 mg QD 7 days + PLD). Limited efficacy was observed, with one RECIST partial response.

Toxicity of AZD7648 + PLD was greater than expected and antitumour activity was limited, leading to early study termination.

Homologous recombination deficiency (HRD) contributes to genomic instability and leads to sensitivity to PARP inhibitors (PARPi). HRD also activates the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING)-interferon pathway, highlighting the need to understand the impact of cGAS-STING-IFN signaling on PARPi efficacy. In this study, we analyzed a cohort of 35 breast cancer patient-derived xenografts and mouse-derived allografts. PARPi sensitivity correlated with HRD, increased genomic instability, and activation of the cGAS-STING-IFN signaling pathway. Single-cell analyses showed that IFN signaling and IFN-based immune interactions were suppressed in preclinical models with acquired resistance to PARPi, lacking concomitant clonal expansion of functional CD8+ T cells. However, the combination of a PARPi and a novel STING agonist (STINGa) increased immune infiltration and resulted in superior antitumor activity in these tumors. Notably, the efficacy of PARPi monotherapy and the combination treatment with a STINGa was dependent on natural killer (NK) cells. In agreement, patients with breast cancer with BRCA1/BRCA2 mutations and good responses to PARPi showed higher abundancy of CD56+ NK cells in the tumor microenvironment and treatment-engaged CD56bright NK cells in the peripheral immune compartment, compared with those with poor responses. Therefore, these findings propose the combination of PARPis and a STINGa as a potential novel strategy to enhance the therapeutic response in patients with acquired PARPi resistance and highlight a pivotal role of NK cells in the PARPi antitumor activity. Significance: PARP inhibitor sensitivity is associated with cGAS-STING-IFN signaling, which can be harnessed by combining PARP inhibitors with STING agonists to overcome acquired resistance and requires NK cells to mediate antitumor immunity. See related commentary by Gohari et al., p. 1747.

Poly (ADP-ribose) polymerase inhibitors (PARPi) exploit DNA repair deficiency in germline BRCA1 and BRCA2 pathogenic variant (gBRCAm) cancers. Haematological toxicity limits chemotherapy-PARPi treatment combinations. In preclinical models we identified a schedule combining olaparib and carboplatin that avoids enhanced toxicity but maintains anti-tumour activity. We investigated this schedule in a neoadjuvant, phase II-III, randomised controlled trial for gBRCAm breast cancers (ClinicalTrials.gov ID:NCT03150576; PARTNER). The research arm included carboplatin (Area Under the Curve 5, 3-weekly); paclitaxel (80 mg/m2, weekly) day 1, plus olaparib (150 mg twice daily) day 3-14 (4 cycles), followed by anthracycline-containing chemotherapy (3 cycles); control arm gave chemotherapy alone. The primary endpoint, pathological complete response rate, showed no statistical difference between research 64.1% (25/39); control 69.8% (30/43) (p = 0.59). However, estimated survival outcomes at 36-months demonstrated improved event-free survival: research 96.4%, control 80.1% (p = 0.04); overall survival: research 100%, control 88.2% (p = 0.04) and breast cancer specific survival: research 100%, control 88.2% (p = 0.04). There were no statistical differences in relapse-free survival and distant disease-free survival, both were: research 96.4%, control 87.9% (p = 0.20). Similarly, local recurrence-free survival and time to second cancer were both: research 96.4%, control 87.8% (p = 0.20). The PARTNER trial identified a safe, tolerable schedule combining neoadjuvant chemotherapy with olaparib. This combination demonstrated schedule-dependent overall survival benefit in early-stage gBRCAm breast cancer. This result needs confirmation in larger trials.

CRISPR-based genetically modified scaffold-free biomaterials, including extracellular vehicles, cell sheets, cell aggregates, organoids and organs, have attracted significant attention in the fields of regenerative medicine and tissue engineering in recent years. With a wide range of applications in gene therapy, modeling disease, tissue regeneration, organ xenotransplantation, modeling organogenesis as well as gene and drug screening, they are at a critical juncture from clinical trials to therapeutic applications. Xenografts have already been tested on non-human primates and humans. However, we have to admit that a series of obstacles still need to be addressed, such as immune response, viral infection, off-target effects, difficulty in mass production, and ethical issues. Therefore, future research should pay more attention to improving their safety, accuracy of gene editing, flexibility of production, and ethical rationality. This review summarizes various types of CRISPR-based genetically modified scaffold-free biomaterials, including their preparation procedures, applications, and possible improvements.

NMR spectroscopy of biomolecules provides atomic level information into their structure, dynamics and interactions with their binding partners. However, signal attenuation from line broadening caused by fast relaxation and signal overlap often limits the application of NMR to large macromolecular systems. Here we leverage the slow relaxation properties of 13C nuclei attached to 19F in aromatic 19F-13C spin pairs as well as the spin-spin coupling between the fluorinated 13C nucleus and the hydrogen atom at the meta-position to record two-dimensional 1H-13CF correlation spectra with transverse relaxation-optimized spectroscopy selection on 13CF. To accomplish this, we synthesized [4-19F13Cζ; 3,5-2H2ε] Phe, engineered for optimal relaxation properties, and adapted a residue-specific route to incorporate this residue globally into proteins and a site-specific 4-19F Phe encoding strategy. This approach resulted in narrow linewidths for proteins ranging from 30 kDa to 180 kDa, enabling interaction studies with small-molecule ligands without requiring specialized 19F-compatible probes.

Triple negative form of breast cancer (abbreviated as TNBC) is considered as the most aggressive form causing high mortality worldwide. Different treatment modalities such as chemotherapy, surgery, hormonal therapy and radiation therapy are employed for eliminating breast cancer, which are associated with many limitations. Therefore, considering the significance of metal nanoparticles in the biomedical sector, especially gold nanoparticles, in the current manuscript, we have designed and developed a combinatorial approach for synthesizing two types of gold (Au) nanoformulations (Au-Dex-MUA-Rapa, Au-Dex-MUA-Ola) using 11-mercaptoundecanoic acid (MUA), dexamethasone (Dex) (glucocorticoid receptor targeted molecule) along with rapamycin (Rapa: inhibitor of mTOR) or olaparib (Ola: inhibitor of PARP) against TNBC. These gold nanoformulations were characterized thoroughly using several analytical techniques such as TEM, spectroscopy, DLS, HPLC and ICPOES. The in vitro MTT assays (normal cells: HEK-293 and CHO) and ex vivo CAM assay displays the biocompatible properties of the conjugated gold nanoformulations. Further, the anticancer properties of the conjugated gold nanoformulations in TNBC cells (MDA-MB-231) were evaluated through several in vitro experiments along with plausible mechanism of action. The intraperitoneal administration of gold nanoformulations into the breast tumor bearing BALB/c mice inhibits the tumor growth and increases their survivability. Additionally, we have investigated the plausible mechanistic studies behind the anticancer properties of the conjugated gold nanoformulations. Finally, we have found the non-toxic nature of these nanoformulations at therapeutic dose. Considering the above results, the conjugated gold nanoformulations could be used as an alternative therapeutic strategy for the treatment of breast carcinoma in near future.

Oxidative DNA damage, resulting from endogenous cellular processes and external sources plays a significant role in mutagenesis, cancer progression, and the pathogenesis of neurological disorders. Base Excision Repair (BER) is involved in the repair of base modifications such as oxidations or alkylations as well as single strand breaks. The DNA glycosylase OGG1, initiates the BER pathway by the recognition and excision of 8oxoG, the most common oxidative DNA lesion, in both nuclear and mitochondrial DNA. Beyond DNA repair, OGG1 modulates transcription, particularly pro-inflammatory genes, linking oxidative DNA damage to broader biological processes like inflammation and aging. In cancer therapy, BER inhibition has emerged as a promising strategy to enhance treatment efficacy. Targeting OGG1 sensitizes cells to chemotherapies, radiotherapies, and PARP inhibitors, presenting opportunities to overcome therapy resistance. Additionally, OGG1 activators hold potential in mitigating oxidative damage associated with aging and neurological disorders. This review presents the development of several inhibitors and activators of OGG1 and how they have contributed to advance our knowledge in the fundamental functions of OGG1. We also discuss the new opportunities they provide for clinical applications in treating cancer, inflammation and neurological disorders. Finally, we also highlight the challenges in targeting OGG1, particularly regarding the off-target effects recently reported for some inhibitors and how we can overcome these limitations.

Targeting the DNA damage response (DDR) is a key strategy in cancer therapy, leveraging tumour-specific weaknesses in DNA repair pathways to enhance treatment efficacy. Traditional treatments, such as chemotherapy and radiation, use a broad, damage-inducing approach, whereas precision oncology aims to tailor therapies to specific genetic mutations or vulnerabilities. The clinical success of PARP inhibitors has renewed the interest in targeting DNA repair as a therapeutic strategy. Expanding the precision oncology toolbox by targeting the base excision repair (BER) pathway presents a promising avenue for cancer therapy, particularly in tumours that rely heavily on this pathway due to deficiencies in other DNA repair mechanisms. This review discusses how targeting BER could improve treatment outcomes, particularly in DDR-defective cancers. With ongoing advancements in biomarker discovery and drug development, BER-targeted therapies hold significant potential for refining precision oncology approaches.

A retrospective, multi-center propensity score-matched (PMS) analysis was conducted to investigate the efficacy and safety of the treatment strategy that combines bevacizumab and chemotherapy for patients with relapsed epithelial ovarian cancer (EOC) who previously received poly ADP-ribose polymerase inhibitors (PARPis).

A total of 250 ovarian cancer (OC) patients relapsed after PARPi received chemotherapy with or without bevacizumab at 4 medical centers were enrolled in the study. For both treatments, Kaplan-Meier analysis and Cox regression were used to compare PFS.

In the multivariable analysis of 250 patients, the incorporation of bevacizumab into chemotherapy demonstrated a significant enhancement in PFS (hazard ratio [HR]=0.49; 95% confidence interval [CI]=0.34-0.72; p<0.001). Fifty-five patients were enrolled in Group A (bevacizumab combined with chemotherapy) and 55 were enrolled in Group B (chemotherapy alone regime) after PSM analysis. A statistically significant difference in PFS was observed between the 2 regimens (HR=0.62; 95% CI=0.40-0.97; p=0.036), suggesting that the bevacizumab combined with chemotherapy regimen confers superior clinical benefits. The median PFS was 11 months in Group A and 9 months in Group B. A significant variation was noted in PFS between patients without RCRS (HR=0.50; 95% CI=0.30-0.82) and the platinum-resistant subgroup (HR=0.31; 95% CI=0.14-0.68). Adverse effects of Grade 3-4 were more prevalent in Group A than in Group B. Additionally, instances of severe hypertension and bowel perforation were reported solely within Group A.

In patients diagnosed with EOC relapsed after PARPi, the regime of chemotherapy combined with bevacizumab is associated with better PFS.

Homologous recombination deficiency (HRD) leads to genomic instability, and patients with HRD can benefit from HRD-targeting therapies. Previous studies have primarily focused on identifying HRD biomarkers using data from a single technology. Here we integrated features from different genomic data types, including total copy number (CN), allele-specific copy number (ASCN) and single nucleotide variants (SNV). Using a semi-supervised method, we developed HRD classifiers from 1404 breast tumours across two datasets based on their BRCA1/2 status, demonstrating improved HRD identification when aggregating different data types. Notably, HRD-positive tumours in ER-negative disease showed improved survival post-adjuvant chemotherapy, while HRD status strongly correlated with neoadjuvant treatment response. Furthermore, our analysis of cell lines highlighted a sensitivity to PARP inhibitors, particularly rucaparib, among predicted HRD-positive lines. Exploring somatic mutations outside BRCA1/2, we confirmed variants in several genes associated with HRD. Our method for HRD classification can adapt to different data types or resolutions and can be used in various scenarios to help refine patient selection for HRD-targeting therapies that might lead to better clinical outcomes.

Sequencing of neuroblastoma (NB) tumors has revealed genetic alterations in genes involved in DNA damage response (DDR) pathways. However, roles for specific alterations of DDR genes in pediatric solid tumors remain poorly understood. To address this, mutations in the DDR pathway including Brca2, Atm, and Palb2 were incorporated into an established zebrafish MYCN transgenic model (Tg(dbh:EGFP-MYCN)). These mutations enhance NB formation and metastasis and result in upregulation of cell-cycle checkpoint and DNA damage repair signatures, revealing molecular vulnerabilities in DDR-deficient NB. DDR gene knockdown in zebrafish and human NB cells increases sensitivity to the poly(ADP-ribose) polymerase (PARP) inhibitor olaparib, and this effect is enhanced by inhibition of the ataxia telangiectasia and rad3-related (ATR) kinase. This work provides in vivo evidence demonstrating that alterations in certain DDR-pathway genes promote aggressive NB and supports combination PARP + ATR inhibitor therapy for NB patients with tumors harboring specific genetic alterations in DDR.

As the healthcare industry evolves towards precision medicine, methods to assess the value of integrating companion diagnostics in clinical practice through adequate reimbursement levels are becoming essential. Cost-effectiveness analysis is an established tool used to inform the reimbursement of health technologies.

A decision-tree model was developed to estimate the incremental cost-effectiveness of companion BRCA testing and olaparib use versus no testing and the standard of care (SoC) for patients with BRCA-mutated high-risk HER2-negative early breast cancer from a UK NHS/PSS perspective.

BRCA testing combined with treatment with adjuvant olaparib was associated with an incremental cost-effectiveness ratio (ICER) of £49,327 per quality-adjusted life-year (QALY) gained and an ICER of £86,349 per QALY gained for patients with triple-negative breast cancer (TNBC) and human epidermal growth factor receptor 2 negative/hormone receptor-positive (HER2-/HR+) breast cancer, respectively, compared to no testing and treatment with SoC. This difference in ICER is due to significantly improved outcomes for patients with TNBC who were treated with targeted therapy. For both patient subgroups with early breast cancer, testing and olaparib improved patient outcomes and, despite its relatively high cost, the test and treat strategy was deemed to represent an acceptable use of resources.

The advancement of high-throughput sequencing technologies, coupled with the rise of targeted treatments in recent years, has facilitated a shift from conventional medical practices to individualized oncology therapeutic approaches. Our analysis presented the value of combining genetic sequencing and targeted therapy for patients with breast cancer carrying BRCA mutations and also provided the prototype of a testing model that can be utilized to promote precision medicine for better patient outcomes.

NAD+ is an important cofactor involved in regulating many biochemical processes in cells. An imbalance in NAD+/NADH ratio is linked to many diseases. NAD+ is depleted in diabetes, cardiovascular and neurodegenerative diseases, and in aging, and is increased in tumor cells. NAD+ is generated in cells via the de novo, Preiss-Handler, and salvage pathways. Most of the cellular NAD+ is generated through Nampt activation, a key rate-limiting enzyme that is involved in the salvage pathway. Restoration of NAD+/NADH balance offers therapeutic advantages for improving tissue homeostasis and function. NAD+ is known to benefit and restore the body's physiological mechanisms, including DNA replication, chromatin and epigenetic modifications, and gene expression. Recent studies elucidate the role of NAD+ in cells utilizing transgenic mouse models. Translational new therapeutics are positioned to utilize the NAD+ restoration strategies for overcoming the drawbacks that exist in the pharmacological toolkit. The present review highlights the significance of Nampt-NAD+ axis as a major player in energy metabolism and provides an overview with insights into future strategies, providing pharmacological advantages to address current and future medical needs.

The tumour-suppressor protein BRCA2 has a central role in homology-directed DNA repair by enhancing the formation of RAD51 filaments on resected single-stranded DNA generated at double-stranded DNA breaks and stimulating RAD51 activity1,2. Individuals with BRCA2 mutations are predisposed to cancer; however, BRCA2-deficient tumours are often responsive to targeted therapy with PARP inhibitors (PARPi)3-6. The mechanism by which BRCA2 deficiency renders cells sensitive to PARPi but with minimal toxicity in cells heterozygous for BRCA2 mutations remains unclear. Here we identify a previously unknown role of BRCA2 that is directly linked to the effect of PARP1 inhibition. Using biochemical and single-molecule approaches, we demonstrate that PARPi-mediated PARP1 retention on a resected DNA substrate interferes with RAD51 filament stability and impairs RAD51-mediated DNA strand exchange. Full-length BRCA2 protects RAD51 filaments and counteracts the instability conferred by PARPi-mediated retention by preventing the binding of PARP1 to DNA. Extending these findings to a cellular context, we use quantitative single-molecule localization microscopy to show that BRCA2 prevents PARPi-induced PARP1 retention at homologous-recombination repair sites. By contrast, BRCA2-deficient cells exhibit increased PARP1 retention at these lesions in response to PARPi. These results provide mechanistic insights into the role of BRCA2 in maintaining RAD51 stability and protecting homologous-recombination repair sites by mitigating PARPi-mediated PARP1 retention.

Poly(ADP-ribosyl)ation (PARylation), a reversible post-translational modification mediated by poly(ADP-ribose) polymerases (PARPs), plays crucial roles in DNA replication and DNA damage repair. Since interfering PARylation induces selective cytotoxicity in tumor cells with homologous recombination defects, PARP inhibitors (PARPi) have significant clinical impacts in treating BRCA-mutant cancer patients. Likewise, dePARylation is also essential for optimal DNA damage response and genomic stability. This process is mediated by a group of dePARylation enzymes, such as poly(ADP-ribose) glycohydrolase (PARG). Currently, several novel PARG inhibitors have been developed and examined in preclinical and clinical studies, demonstrating promising anti-cancer activity distinct from PARP inhibitors. This review discusses the role of dePARylation in genome stability and the potential of PARG inhibitors in cancer therapy.

Breast and prostate cancer are among the most commonly diagnosed cancers worldwide. Recent advances in tumor sequencing and gene studies have led to a paradigm shift from treatment centered on the type of tumor to therapy more focused on specific immune phenotype markers and molecular alterations. In this review, we discuss the utility and function of talazoparib concerning prostate cancer treatment and summarize recent and planned clinical trials on talazoparib. We searched medical databases for articles relating to the use of talazoparib in prostate cancer from inception. Poly ADP ribose polymerase (PARP) is a family of 17 necessary DNA repair enzymes responsible for base excision repair, single-strand break repair, and double-strand break repair. PARP inhibitors are a class of oral targeted therapies that compete for the NAD + binding site on PARP molecules. Talazoparib, a potent PARP inhibitor, has emerged as a significant therapeutic option in the treatment of metastatic castration-resistant prostate cancer (mCRPC), particularly for patients with specific genetic alterations. Its role as a PARP inhibitor makes it a targeted therapy, focusing on cancer cells with DNA repair deficiencies. Talazoparib's role as a biomarker-directed therapy in advanced prostate cancer has been increasingly recognized. The TALAPRO-1 demonstrated durable antitumor activity in mCRPC patients. TALAPRO-2 is a notable clinical trial, specifically examining the effectiveness of Talazoparib when used in combination therapies. Current investigations demonstrate a significant improvement in survival outcomes for the patients of mCRPC, making Talazoparib a promising intervention.

This work demonstrates that FA pathway mutations, which are frequently observed in sporadic AML, induce hypersensitivity to PLK1 inhibition, providing rationale for a novel synthetic lethal therapeutic strategy for this patient population.

Genomic loss-of-heterozygosity (gLOH) consists in the loss of chromosomal regions and is associated with homologous recombination repair (HRR) system deficiency. We explored the role of gLOH and HRR-related gene alterations in metastatic colorectal cancer (mCRC).

FoundationOne CDx assay was used to determine the percentage of gLOH and the presence of alterations in 27 HRR-related genes in archival chemo-naïve tumor tissues of patients with mCRC treated with first-line oxaliplatin- or irinotecan-based doublets and triplet ± anti-PD-L1.

Overall, 243 samples were analyzed. None of the nine deficient mismatch repair/microsatellite instability high tumors were gLOH-high, while 16 (7%) of 234 proficient mismatch repair/microsatellite stable (pMMR/MSS) tumors were gLOH-high. In the pMMR/MSS population, six (3%) and 18 (8%) had at least a biallelic or monoallelic HRR-related gene alteration, respectively. Among patients receiving FOLFOXIRI alone (n = 68) or with an anti-PD-L1 (N = 90), higher benefit from the addition of the immune checkpoint inhibitor (ICI) was observed in the gLOH-high subgroup (n = 12), in terms of both progression-free survival (PFS; Pint = .02) and overall survival (OS; Pint = .03). No differences in PFS or OS were reported between patients treated with first-line oxaliplatin- (n = 40) versus irinotecan-based doublets (n = 25) or with the triplet FOLFOXIRI (n = 68) versus doublets (n = 65), according to the gLOH status. Among patients not receiving an anti-PD-L1, longer PFS was observed in the gLOH-low group (n = 138) versus the gLOH-high (n = 6) group (5.1 v 12.1 months; hazard ratio, 8.73 [95% CI, 3.64 to 20.9]; P < .001), and this was confirmed in the multivariate analysis (P < .001). No prognostic impact of monoallelic or biallelic HRR-related gene alterations was shown.

In pMMR/MSS mCRC, gLOH-high was associated with worse prognosis and higher benefit from the addition of anti-PD-L1 agents to chemotherapy. If confirmed in larger series, these results may inform the design of clinical trials.

Patients with high-grade serous ovarian carcinoma (HGSOC) often have a personal and/or family history of breast cancers. However, the clinical association and underlying molecular interaction between breast cancer and HGSOC is not well understood. In this study, the clinical characteristics and outcomes of HGSOC patients with or without breast cancer were compared.

Eligible patient information was extracted from the Surveillance, Epidemiology, and End Results database. Kaplan-Meier and Cox proportional hazards regression models were used to determine survival outcomes and prognostic factors.

A total of 3065 HGSOC (ICD-O-3 code 8461/3) patients were identified from 1975 to 2020, among whom 239 (9.56%) had co-existing breast cancers. HGSOC with breast cancers tended to have more stage I-II ovarian cancer (20.92% vs 13.79%), less metastatic diseases (25.1% vs 32.13%) and had a higher probability of undergoing surgery (94.1% vs 87.9%). The overall survival of HGSOC patients with breast cancer was better than that of patients without breast cancer (HR = 0.77, 95% CI 0.65 to 0.91; P = 0.0015). Further, patients who developed ovarian cancer before breast cancer had better overall survival than those who developed breast cancer before or simultaneously with ovarian cancer (HR = 0.35, 95% CI 0.23 to 0.52; P < 0.001).

HGSOC combined with breast cancer is a common phenomenon. HGSOC patients with breast cancer, especially those diagnosed with ovarian cancer before breast cancer have a better prognosis. Further validation is warranted and more genetic and mechanistical study is needed.

Prostate cancer is a leading malignancy among men. While early-stage prostate cancer can be effectively managed, metastatic prostate cancer remains incurable, with a median survival of 3-5 years. The primary treatment for advanced prostate cancer is androgen deprivation therapy (ADT), but resistance to ADT often leads to castrationresistant prostate cancer (CRPC), presenting a significant therapeutic challenge. The advent of precision medicine has introduced promising new treatments, including PARP inhibitors (PARPi), which target defects in DNA repair mechanisms in cancer cells. PARPi have shown efficacy in treating advanced prostate cancer, especially in patients with metastatic CRPC (mCRPC) harboring homologous recombination (HR)-associated gene mutations. Despite these advancements, resistance to PARPi remains a critical issue. Here, we explored the primary mechanisms of PARPi resistance in prostate cancer. Key resistance mechanisms include homologous recombination recovery through reverse mutations in BRCA genes, BRCA promoter demethylation, and non-degradation of mutated BRCA proteins. The tumor microenvironment and overactivation of the base excision repair pathway also play significant roles in bypassing PARPi-induced synthetic lethality. In addition, we explored the clinical implications and therapeutic strategies to overcome resistance,emphasizing the need for precision medicine approaches. Our findings highlight the need for comprehensive strategies to improve PARPi sensitivity and effectiveness,ultimately aiming to extend patient survival and improve the quality of life for those with advanced prostate cancer. As our understanding of PARPi resistance evolves, more diverse and effective individualized treatment regimens will emerge.

Poly-ADP-ribosylation (PARylation) is a reversible posttranslational modification that occurs in higher eukaryotes. While thousands of PARylated substrates have been identified, the specific biological functions of most PARylated proteins remain elusive. PARylation stoichiometry is a critical parameter to assess the potential functions of a PARylated protein. Here, we developed a large-scale strategy to measure the absolute stoichiometries of protein PARylation. By integrating mild cell lysis, boronate enrichment and carefully designed titration experiments, we were able to determine the PARylation stoichiometries for a total of 235 proteins. This approach enables the capture of all PARylation events on various amino acid acceptors. We revealed that PARylation occupancy spans over three orders of magnitude. However, most PARylation events occur at low stoichiometric values (median 0.578%). Notably, we observed that high stoichiometry PARylation (>1%) predominantly targets proteins involved in transcription regulation and chromatin remodeling. Thus, our study provides a systems-scale, quantitative view of PARylation stoichiometries under genotoxic conditions, which serves as invaluable resources for future functional studies of this important protein posttranslational modification.

Chronic lymphocytic leukemia (CLL) is a clinically and genetically heterogenous disease. Recent next-generation sequencing (NGS) studies have uncovered numerous low-frequency mutated genes in CLL patients, with SAMHD1 emerging as a candidate driver gene. However, the biological and clinical implications of SAMHD1 mutations remain unclear. Using CRISPR/Cas9, we generated CLL models to investigate the impact of SAMHD1 deficiency on pathogenesis and explore therapeutic strategies. Moreover, we performed NGS in treatment-naïve CLL patients to characterize SAMHD1 mutations and employed RNA-sequencing to evaluate their clinical significance. Our study shows that SAMHD1 inactivation impairs the DNA damage response by reducing homologous recombination efficiency through BRCA1 and RAD51 dysregulation. Importantly, SAMHD1 colocalizes with BRCA1 at DNA damage sites in CLL cells. This research also identifies that SAMHD1-mutated cells are more sensitive to PARP inhibition. Clinically, SAMHD1 dysfunction negatively impacts clinical outcome of CLL cases: SAMHD1 mutations reduce failure-free survival (median 46 vs 57 months, p = 0.033), while low SAMHD1 expression associates with shorter time to first treatment (median 47 vs 77 months; p = 0.00073). Overall, this study elucidates that SAMHD1 dysfunction compromises DNA damage response mechanisms, potentially contributing to unfavorable clinical outcomes in CLL, and proposes PARP-inhibitors as a potential therapeutic approach for SAMHD1-mutated CLL cells.

RNA metabolism has been extensively studied in DNA double-strand break (DSB) repair. The RNA acetyltransferase N-acetyltransferase 10 (NAT10)-mediated N4-acetylcytidine (ac4C) modification in DSB repair remains largely elusive. In this study, we aim to decipher the role for ac4C modification by NAT10 in DSB repair in hepatocellular carcinoma (HCC).

Laser micro-irradiation and chromatin immunoprecipitation (ChIP) were used to assess the accumulation of ac4C modification and NAT10 at DSB sites. Cryo-electron microscopy (cryo-EM) was used to determine the structures of NAT10 in complex with its inhibitor, remodelin. Hepatocyte-specific deletion of NAT10 mouse models were adopted to detect the effects of NAT10 on HCC progression. Subcutaneous xenograft, human HCC organoid and patient-derived xenograft (PDX) model were exploited to determine the therapy efficiency of the combination of a poly (ADP-ribose) polymerase 1 (PARP1) inhibitor (PARPi) and remodelin.

NAT10 promptly accumulates at DSB sites, where it executes ac4C modification on RNAs at DNA:RNA hybrids dependent on PARP1. This in turn enhances the stability of DNA:RNA hybrids and promotes homologous recombination (HR) repair. The ablation of NAT10 curtails HCC progression. Furthermore, the cryo-EM yields a remarkable 2.9 angstroms resolution structure of NAT10-remodelin, showcasing a C2 symmetric architecture. Remodelin treatment significantly enhanced the sensitivity of HCC cells to a PARPi and targeting NAT10 also restored sensitivity to a PARPi in ovarian and breast cancer cells that had developed resistance.

Our study elucidated the mechanism of NAT10-mediated ac4C modification in DSB repair, revealing that targeting NAT10 confers synthetic lethality to PARP inhibition in HCC. Our findings suggest that co-inhibition of NAT10 and PARP1 is an effective novel therapeutic strategy for patients with HCC and have the potential to overcome PARPi resistance.

The development of poly (ADP-ribose) polymerase inhibitors (PARPis) is widely considered a therapeutic milestone in the management of BRCA1/2-deficient malignancies. Since a growing number of cancer treatment guidelines include PARPis, the inevitably emerging PARPi resistance becomes a serious limitation that must be addressed. Targeting the DNA damage response signaling kinase, ATR (ataxia telangiectasia and rad3-related serine/threonine kinase), activated in response to PARPi-induced replication stress, represents a promising approach in fighting PARPi-resistant cancers. The success of this combination therapy in preclinical models has inspired efforts to translate its potential through extensive clinical research and clinical trials. However, the available clinical evidence suggests that PARPi/ATRi combinations have yet to reach their anticipated therapeutic potential. In this review, we summarize work elucidating mechanisms underpinning the effectiveness of ATRi in fighting PARPi resistance and review translational studies reporting efficacy in different types of cancer. Finally, we discuss potential biomarkers of patient selection for customized combinations of PARPi/ATRi treatments.

Immunotherapy of cancer is now an essential pillar of treatment for patients with many individual tumor types. Novel immune targets and technical advances are driving a rapid exploration of new treatment strategies incorporating immune agents in cancer clinical practice. Immunotherapies perturb a complex system of interactions among genomically unstable tumor cells, diverse cells within the tumor microenvironment including the systemic adaptive and innate immune cells. The drive to develop increasingly effective immunotherapy regimens is tempered by the risk of immune-related adverse events. Evidence-based biomarkers that measure the potential for therapeutic response and/or toxicity are critical to guide optimal patient care and contextualize the results of immunotherapy clinical trials. Responding to the lack of guidance on biomarker testing in early-phase immunotherapy clinical trials, we propose a definition and listing of essential biomarkers recommended for inclusion in all such protocols. These recommendations are based on consensus provided by the Society for Immunotherapy of Cancer (SITC) Clinical Immuno-Oncology Network (SCION) faculty with input from the SITC Pathology and Biomarker Committees and the Journal for ImmunoTherapy of Cancer readership. A consensus-based selection of essential biomarkers was conducted using a Delphi survey of SCION faculty. Regular updates to these recommendations are planned. The inaugural list of essential biomarkers includes complete blood count with differential to generate a neutrophil-to-lymphocyte ratio or systemic immune-inflammation index, serum lactate dehydrogenase and albumin, programmed death-ligand 1 immunohistochemistry, microsatellite stability assessment, and tumor mutational burden. Inclusion of these biomarkers across early-phase immunotherapy clinical trials will capture variation among trials, provide deeper insight into the novel and established therapies, and support improved patient selection and stratification for later-phase clinical trials.

Background/Objectives: Recently, there has been great interest in metallopharmaceuticals as potential anticancer agents. In this context, presented studies aim to synthesize and evaluate of two copper(II) complexes derived from phthalazine- and imidazoline-based ligands against on three human cancer cell lines: cervix epithelial cell line (HeLa), breast epithelial-like adenocarcinoma (MCF-7), and triple-negative breast epithelial cancer cell line (MDA-MB-231), as well as non-tumorigenic cell line (HDFa). Moreover their antimicrobial, and antioxidant properties were assessed. Methods: The synthetized compounds-both free ligands L1, L2, L3 and copper(II) complexes C1 and C2-were characterized by elemental analysis, infrared spectroscopy. Additionally, a single-crystal X-ray diffraction studies we performed for free ligand L3 and its copper(II) complex C2. The stability of Cu(II)-complexes C1 and C2 was evaluated by UV-Vis spectroscopy. The cytotoxic potency of free ligands and their copper(II) complexes was estimated on HeLa, MCF-7, MDA-MB-231, as well as non-cancerous HDFa by use of an MTT assay after 48 h of incubation. Moreover, the antimicrobial activity of ligands L1 and L3 and their copper(II) complexes C1 and C2 was evaluated using reference strains of the following bacteria and yeasts: Staphylococcus aureus, Escherichia coli, and Candida albicans. The free radical scavenging properties of free ligands L1, L3 and the corresponding copper(II) complexes C1, C2 was tested with two colorimetric methods-ABTS, DPPH, and reduction ability assay (FRAP). Additionally, the ADME webtool was used to assess the drug-likeness of the synthesized compounds, as well as their physicochemical and pharmacokinetic properties. Results: Copper(II) complex C2 exhibited antitumor properties towards MDA-MB-231 compared with Cisplatin (cancer cell viability rate of 23.6% vs. 22.5%). At a concentration of 200 μg/mL, complexes C1 and C2 were less cytotoxic than the reference Cisplatin against a normal, non-cancerous skin fibroblast cell line (HDFa). According to in vitro tests, C2 reduced the viability of HeLa, MCF-7, and MDA-MB-231 cells by about 57.5-81.2%. It was evident that all compounds were devoid of antibacterial or antifungal activity. In vitro assays revealed that a moderate antiradical effect was observed for free ligand L1 containing phthalazin-1(2H)-imine in the ABTS radical scavenging assay (IC50 = 23.63 µg/mL). Conclusions: The anticancer studies revealed that the most potent compound was copper(II) complex C2 bearing a phthalazin-1(2H)-one scaffold. None of the tested compounds showed antimicrobial or antifungal activity. This feature seems to be beneficial in terms of their potential uses as anticancer agents in the future. In vitro antiradical assays revealed that a moderate antioxidant effect was observed only for free ligand L1 containing phthalazin-1(2H)-imine.

The targeting of cancer stem cells (CSCs) has proven to be an effective approach for limiting tumor progression, thus necessitating the identification of new drugs with anti-CSC activity. Through a high-throughput drug repositioning screen, we identify the antibiotic Nifuroxazide (NIF) as a potent anti-CSC compound. Utilizing a click chemistry strategy, we demonstrate that NIF is a prodrug that is specifically bioactivated in breast CSCs. Mechanistically, NIF-induced CSC death is a result of a synergistic action that combines the generation of DNA interstrand crosslinks with the inhibition of the Fanconi anemia (FA) pathway activity. NIF treatment mimics FA-deficiency through the inhibition of STAT3, which we identify as a non-canonical transcription factor of FA-related genes. NIF induces a chemical HRDness (Homologous Recombination Deficiency) in CSCs that (re)sensitizes breast cancers with innate or acquired resistance to PARP inhibitor (PARPi) in patient-derived xenograft models. Our results suggest that NIF may be useful in combination with PARPi for the treatment of breast tumors, regardless of their HRD status.

The concomitant use of antibiotics, especially beta lactams, during acute EBV infection is widely associated with an increased risk of skin manifestations; the actual pathophysiology and prevalence of this phenomenon are still debated.

We present the first reported case of atypical exanthema associated with amoxicillin intake in a patient with EBV-related nasopharyngeal carcinoma. We recorded a pattern in the plasma EBV-DNA load consisting of a significant increase at the onset of the rash with a sudden remission after its resolution. The patient recovered without sequelae.

The temporal relationship and the reported data on rash morphology, clinical findings and triggering factors support a possible correlation between the intake of beta-lactam antibiotics, particularly amoxicillin, and the onset of cutaneous manifestations in a patient with nasopharyngeal carcinoma. Such reactions can be a challenging differential diagnosis and may warrant increased provider consideration when choosing to prescribe beta lactams in patients affected by nasopharyngeal cancer.

AT-rich interactive domain-containing protein 1A (ARID1A), a core constituent of the switch/sucrose nonfermentable (SWI/SNF) complex, is mutated in approximately 10% of colorectal cancers. Whereas ARID1A deficiency corresponds to heightened immune activity in colorectal cancer, immune checkpoint inhibitors (ICI) have shown limited efficacy in these tumors. The discovery of targetable vulnerabilities associated with ARID1A deficiency in colorectal cancer could expand treatment options for patients. In this study, we demonstrated that arachidonic acid (AA) metabolism inhibitors synergize with ICIs in ARID1A-deficient colorectal cancer by enhancing the activity of CD8+ T cells and inhibiting vasculogenic mimicry. Epigenetic analysis using ATAC-seq and ChIP-qPCR revealed that the lack of ARID1A results in reduced levels of PTGS1 and PTGS2, the key enzymes that control the AA pathway. Low PTGS1 and PTGS2 expression generated a reliance on the remaining functionality of the AA pathway in ARID1A-deficient cells. The AA pathway inhibitor aspirin selectively inhibited the growth of ARID1A-deficient colorectal cancer, and aspirin sensitized tumors lacking ARID1A to immunotherapy. Together, these findings suggest that blocking AA metabolism can enhance immune responses against tumors by activating CD8+ T cells and inhibiting vasculogenic mimicry, which synergizes with ICIs to improve treatment of ARID1A-deficient colorectal cancer. Significance: The arachidonic acid pathway is a metabolic vulnerability in ARID1A-deficient colorectal cancer that can be targeted with aspirin to suppress tumor growth and enhance sensitivity to immunotherapy, providing a promising therapeutic strategy.

Alternative end-joining (alt-EJ) is an error-prone DNA repair pathway that cancer cells deficient in homologous recombination rely on, making them vulnerable to synthetic lethality via inhibition of poly(ADP-ribose) polymerase (PARP). Targeting alt-EJ effector DNA polymerase theta (POLθ), which synergizes with PARP inhibitors and can overcome resistance, is of significant preclinical and clinical interest. However, the transcriptional regulation of alt-EJ and its interactions with processes driving cancer progression remain poorly understood. Here, we show that alt-EJ is suppressed by hypoxia while positively associated with MYC (myelocytomatosis oncogene) transcriptional activity. Hypoxia reduces PARP1 and POLQ expression, decreases MYC binding at their promoters, and lowers PARylation and alt-EJ-mediated DNA repair in cancer cells. Tumors with HIF1A mutations overexpress the alt-EJ gene signature. Inhibition of hypoxia-inducible factor 1α or HIF1A expression depletion, combined with PARP or POLθ inhibition, synergistically reduces the colony-forming capacity of cancer cells. Deep learning reveals the anticorrelation between alt-EJ and hypoxia across regions in tumor images, and the predictions for these and MYC activity achieve area under the curve values between 0.70 and 0.86. These findings further highlight the critical role of hypoxia in modulating DNA repair and present a strategy for predicting and improving outcomes centered on targeting alt-EJ.