PARP inhibition and immune modulation: scientific rationale and perspectives for the treatment of gynecologic cancers

Tumor Treating Fields (TTFields) induce homologous recombination deficiency in ovarian cancer cells, thus mitigating drug resistance

Background

Ovarian cancer is the leading cause of mortality among gynecological malignancies. Carboplatin and poly (ADP-ribose) polymerase inhibitors (PARPi) are often implemented in the treatment of ovarian cancer. Homologous recombination deficient (HRD) tumors demonstrate increased sensitivity to these treatments; however, many ovarian cancer patients are homologous recombination proficient (HRP). TTFields are non-invasive electric fields that induce an HRD-like phenotype in various cancer types. The current study aimed to investigate the impact of TTFields applied together with carboplatin or PARPi (olaparib or niraparib) in preclinical ovarian cancer models.

Methods

A2780 (HRP), OVCAR3 (HRD), and A2780cis (platinum-resistant) human ovarian cancer cells were treated in vitro with TTFields (1 V/cm RMS, 200 kHz, 72 h), alone or with various drug concentrations. Treated cells were measured for cell count, colony formation, apoptosis, DNA damage, expression of DNA repair proteins, and cell cycle. In vivo, ID8-fLuc (HRP) ovarian cancer cells were inoculated intraperitoneally to C57BL/6 mice, which were then treated with either sham, TTFields (200 kHz), olaparib (50 mg/kg), or TTFields plus olaparib; over a period of four weeks. Tumor growth was analyzed using bioluminescent imaging at treatment cessation; and survival analysis was performed.

Results

The nature of TTFields-drug interaction was dependent on the drug's underlying mechanism of action and on the genetic background of the cells, with synergistic interactions between TTFields and carboplatin or PARPi seen in HRP and resistant cells. Treated cells demonstrated elevated levels of DNA damage, accompanied by G2/M arrest, and induction of an HRD-like phenotype. In the tumor-bearing mice, TTFields and olaparib co-treatment resulted in reduced tumor volume and a survival benefit relative to olaparib monotherapy and to control.

Conclusion

By inducing an HRD-like phenotype, TTFields sensitize HRP and resistant ovarian cancer cells to treatment with carboplatin or PARPi, potentially mitigating a-priori and de novo drug resistance, a major limitation in ovarian cancer treatment.

PAR level mediates the link between ROS and inflammatory response in patients with type 2 diabetes mellitus

BACKGROUND

Type 2 diabetes mellitus (T2DM) is characterized by disrupted glucose homeostasis and metabolic abnormalities, with oxidative stress and inflammation playing pivotal roles in its pathophysiology. Poly(ADP-ribosyl)ation (PARylation) is a post-translational process involving the addition of ADP-ribose polymers (PAR) to target proteins. While preclinical studies have implicated PARylation in the interplay between oxidative stress and inflammation in T2DM, direct clinical evidence in humans remains limited. This study investigates the relationship between oxidative stress, PARylation, and inflammatory response in T2DM patients.

METHODS

This cross-sectional investigation involved 61 T2DM patients and 48 controls. PAR levels were determined in peripheral blood cells (PBMC) by ELISA-based methodologies. Oxidative stress was assessed in plasma and PBMC. In plasma, we monitored reactive oxygen metabolites (d-ROMs) and ferric-reducing antioxidant power. In PBMC, we measured the expression of antioxidant enzymes SOD1, GPX1 and CAT by qPCR. Further, we evaluated the expression of inflammatory mediators such as IL6, TNF-α, CD68 and MCP1 by qPCR in PBMC.

RESULTS

T2DM patients exhibited elevated PAR levels in PBMC and increased d-ROMs in plasma. Positive associations were found between PAR levels and d-ROMs, suggesting a link between oxidative stress and altered PAR metabolism. Mediation analysis revealed that d-ROMs mediate the association between HbA1c levels and PAR, indicating oxidative stress as a potential driver of increased PARylation in T2DM. Furthermore, elevated PAR levels were found to be associated with increased expression of pro-inflammatory cytokines IL6 and TNF-α in the PBMC of T2DM patients.

CONCLUSIONS

This study highlights that hyperactivation of PARylation is associated with poor glycemic control and the resultant oxidative stress in T2DM. The increase of PAR levels is correlated with the upregulation of key mediators of the inflammatory response. Further research is warranted to validate these findings and explore their clinical implications.

Androgen receptor, PARP signaling, and tumor microenvironment: the 'perfect triad' in prostate cancer?

Aberrations in the homologous recombination repair (HRR) pathway in prostate cancer (PCa) provide a unique opportunity to develop therapeutic strategies that take advantage of the reduced tumor ability to repair DNA damage. Poly-ADP-ribose polymerase (PARP) inhibitors (PARPi) have been shown to prolong the survival of PCa patients with HRR defects, particularly in those with Breast Cancer type 1 susceptibility protein/Breast Cancer type 2 susceptibility protein alterations. To expand the benefit of PARPi to patients without detectable HRR alterations, multiple preclinical and clinical studies are addressing potential synergies between PARPi and androgen receptor signaling inhibitors, and these strategies are also being evaluated in combination with other drugs such as immune checkpoint inhibitors. However, the effectiveness of these combining therapies could be hindered by multiple mechanisms of resistance, including also the role played by the immunosuppressive tumor microenvironment. In this review, we summarize the use of PARPi in PCa and the potential synergies with different molecular pathways. However, numerous unanswered questions remain, including the identification of the patient population that could benefit most from PARPi, determining whether to use PARPi as monotherapy or in combination, and finding the optimal timing of PARPi, expanding the use of genomic tests, and optimizing combination therapies.

Understanding the HPV associated cancers: A comprehensive review

Human papillomavirus (HPV), a common cause of sexually transmitted diseases, may cause warts and lead to various types of cancers, which makes it important to understand the risk factors associated with it. HPV is the leading risk factor and plays a crucial role in the progression of cervical cancer. Viral oncoproteins E6 and E7 play a pivotal role in this process. Beyond cervical cancer, HPV-associated cancers of the mouth and throat are also increasing. HPV can also contribute to other malignancies like penile, vulvar, and vaginal cancers. Emerging evidence links HPV to these cancers. Research on the oncogenic effect of HPV is still ongoing and explorations of screening techniques, vaccination, immunotherapy and targeted therapeutics are all in progress. The present review offers valuable insight into the current understanding of the role of HPV in cancer and its potential implications for treatment and prevention in the future.

Primary results and characterization of patients with exceptional outcomes in a phase 1b study combining PARP and MEK inhibition, with or without anti-PD-L1, for BRCA wild-type, platinum-sensitive, recurrent ovarian cancer

BACKGROUND

This phase 1b study (ClinicalTrials.gov identifier NCT03695380) evaluated regimens combining PARP and MEK inhibition, with or without PD-L1 inhibition, for BRCA wild-type, platinum-sensitive, recurrent ovarian cancer (PSROC).

METHODS

Patients with PSROC who had received one or two prior treatment lines were treated with 28-day cycles of cobimetinib 60 mg daily (days 1-21) plus niraparib 200 mg daily (days 1-28) with or without atezolizumab 840 mg (days 1 and 15). Stage 1 assessed safety before expansion to stage 2, which randomized patients who had BRCA wild-type PSROC to receive either doublet or triplet therapy, stratified by genome-wide loss of heterozygosity status (<16% vs. ≥16%; FoundationOne CDx assay) and platinum-free interval (≥6 to <12 vs. ≥12 months). Coprimary end points were safety and the investigator-determined objective response rate (ORR) according to Response Evaluation Criteria in Solid Tumors (RECIST). Potential associations between genetic parameters and efficacy were explored, and biomarker profiles of super-responders (complete response or those with progression-free survival [PFS] >15 months) and progressors (disease progression as the best response) were characterized.

RESULTS

The ORR in patients who had BRCA wild-type PSROC was 35% (95% confidence interval, 20%-53%) with the doublet regimen (n = 37) and 27% (95% confidence interval, 14%-44%) with the triplet regimen (n = 37), and the median PFS was 6.0 and 7.4 months, respectively. Post-hoc analyses indicated more favorable ORR and PFS in the homologous recombination-deficiency-signature (HRDsig)-positive subgroup than in the HRDsig-negative subgroup. Tolerability was consistent with the known profiles of individual agents. NF1 and MKNK1 mutations were associated with sustained benefit from the doublet and triplet regimens, respectively.

CONCLUSIONS

Chemotherapy-free doublet and triplet therapy demonstrated encouraging activity, including among patients who had BRCA wild-type, HRDsig-positive or HRDsig-negative PSROC harboring NF1 or MKNK1 mutations.

PARP Inhibitors: Strategic Use and Optimal Management in Ovarian Cancer

Poly (ADP-ribose) polymerase (PARP) inhibitors have become an established part of the anticancer armamentarium. Discovered in the 1980s, PARP inhibitors (PARPis) were initially developed to exploit the presence of BRCA mutations, which disrupt the homologous recombination repair of deoxyribonucleic acid (DNA) via synthetic lethality, an intrinsic vulnerability caused by the cell's dependence on other DNA repair mechanisms for which PARP is an essential contributor. PARPi use expanded with the demonstration of clinical benefit when other mechanisms of high-fidelity DNA damage response were present in cancer cells called homologous repair deficiency (HRD). Recently, new data have resulted in the voluntary withdrawal of later-line treatment indications for all the available PARPis used in ovarian cancer because of a negative impact on overall survival (OS). PARPi switch maintenance to consolidate a response to platinum-based therapy is recommended for earlier treatment lines to have the greatest impact on the chance of cure and length of survival. This article reviews the clinical utility of PARPis and how to integrate them into best practices.

Exploring the structural-activity relationship of hexahydropyrazino[1,2-d]pyrido[3,2-b][1,4]oxazine derivatives as potent and orally-bioavailable PARP7 inhibitors

PARP7 has emerged as a promising anti-tumor target due to its crucial roles in nucleic acid sensing and immune regulation. Herein, we explored the structural-activity relationship of tricyclic PARP7 inhibitors containing a hexahydropyrazino[1,2-d]pyrido[3,2-b][1,4]oxazine motif. The effects of the chirality of the fused rings, the group conjugated to the fused rings, and the size of the linker on PARP7 inhibition were fully investigated. Our work leads to the discovery of an extremely potent and orally-bioavailable PARP7 inhibitor, namely 18 (PARP7 inhibition IC50 = 0.56 nM), for efficacious treatment of lung cancer in vivo. Notably, 18 showed acceptable bioavailability in ICR mice (F = 33.9%) and Beagle dogs (F = 45.2%). Further investigation of ADME-T properties suggested that 18 has the potential to be developed as a candidate drug molecule for PARP7-sensitive tumors.

Treatment of Ovarian Cancer Beyond PARP Inhibition: Current and Future Options

Ovarian cancer is the leading cause of gynecological cancer death. Improved understanding of the biologic pathways and introduction of poly (ADP-ribose) polymerase inhibitors (PARPi) during the last decade have changed the treatment landscape. This has improved outcomes, but unfortunately half the women with ovarian cancer still succumb to the disease within 5 years of diagnosis. Pathways of resistance to PARPi and chemotherapy have been studied extensively, but there is an unmet need to overcome treatment failure and improve outcome. Major mechanisms of PARPi resistance include restoration of homologous recombination repair activity, alteration of PARP function, stabilization of the replication fork, drug efflux, and activation of alternate pathways. These resistant mechanisms can be targeted to sensitize the resistant ovarian cancer cells either by rechallenging with PARPi, overcoming resistance mechanism or bypassing resistance pathways. Augmenting the PARPi activity by combining it with other targets in the DNA damage response pathway, antiangiogenic agents and immune checkpoint inhibitors can potentially overcome the resistance mechanisms. Methods to bypass resistance include targeting non-cross-resistant pathways acting independent of homologous recombination repair (HRR), modulating tumour microenvironment, and enhancing drug delivery systems such as antibody drug conjugates. In this review, we will discuss the first-line management of ovarian cancer, resistance mechanisms and potential strategies to overcome these.

Harnessing the cooperation between DNA-PK and cGAS in cancer therapies: The cooperation between DNA-PK and cGAS shapes tumour immunogenicity

The cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway is central for the initiation of anti-tumoural immune responses. Enormous effort has been made to optimise the design and administration of STING agonists to stimulate tumour immunogenicity. However, in certain contexts the cGAS-STING axis fuels tumourigenesis. Here, we review recent findings on the regulation of cGAS expression and activity. We particularly focus our attention on the DNA-dependent protein kinase (DNA-PK) complex, that recently emerged as an activator of inflammatory responses in tumour cells. We propose that stratification analyses on cGAS and DNA-PK expression/activation status should be carried out to predict treatment efficacy. We herein also provide insights into non-canonical functions borne by cGAS and cGAMP, highlighting how they may influence tumourigenesis. All these parameters should be taken into consideration concertedly to choose strategies aiming to effectively boost tumour immunogenicity.

Immune checkpoint inhibitors in ovarian cancer: where do we go from here?

Epithelial ovarian cancer (EOC) is the most lethal gynaecological malignancy, and despite advancements in therapeutics, most women unfortunately still succumb to their disease. Immunotherapies, in particular immune checkpoint inhibitors (ICI), have been therapeutically transformative in many tumour types, including gynaecological malignancies such as cervical and endometrial cancer. Unfortunately, these therapeutic successes have not been mirrored in ovarian cancer clinical studies. This review provides an overview of the ovarian tumour microenvironment (TME), particularly factors associated with survival, and explores current research into immunotherapeutic strategies in EOC, with an exploratory focus on novel therapeutics in navigating drug resistance.

Treatment options for molecular subtypes of endometrial cancer in 2023

PURPOSE OF REVIEW

This article reviews treatment strategies in endometrial cancer by molecular subtype.

RECENT FINDINGS

The Cancer Genome Atlas (TCGA) classifies four molecular subtypes of endometrial cancer - mismatch repair-deficient (dMMR)/microsatellite instability-high (MSI-H), copy number high (CNH)/p53abn, copy number low (CNL)/no specific molecular profile (NSMP), and POLEmut - which are validated and highly prognostic. Treatment consideration by subtype is now recommended. FDA-approved immune checkpoint inhibitors (ICIs) include pembrolizumab and dostarlimab for previously treated dMMR/MSI-H EC, and pembrolizumab/lenvatinib for mismatch repair-proficient/microsatellite-stable endometrial cancer, including CNH/p53abn and CNL/NSMP. ICIs are being studied as first-line therapy in advanced/recurrent endometrial cancer by MMR status, as well as in combination with other targeted agents. Trastuzumab is NCCN compendium listed for HER2-positive serous endometrial cancer, which are primarily p53-abnormal. Antibody-drug conjugates targeting low and high HER2 levels show promise in breast cancer, and are beginning to be studied in endometrial cancer. In addition to hormonal therapy, maintenance therapy with selinexor (XPO1-inhibitor) showed potential benefit in p53 -wildtype endometrial cancer and is being investigated prospectively. Multiple prospective trials are evaluating de-escalation of care for POLEmut endometrial cancer given favorable survival regardless of adjuvant therapy.

SUMMARY

Molecular subtyping has important prognostic and therapeutic implications and should be guiding patient management and clinical trial design in endometrial cancer.

Auranofin Synergizes with the PARP Inhibitor Olaparib to Induce ROS-Mediated Cell Death in Mutant p53 Cancers

Auranofin (AF) is a potent, off-patent thioredoxin reductase (TrxR) inhibitor that efficiently targets cancer via reactive oxygen species (ROS)- and DNA damage-mediated cell death. The goal of this study is to enhance the efficacy of AF as a cancer treatment by combining it with the poly(ADP-ribose) polymerase-1 (PARP) inhibitor olaparib (referred to as ‘aurola’). Firstly, we investigated whether mutant p53 can sensitize non-small cell lung cancer (NSCLC) and pancreatic ductal adenocarcinoma (PDAC) cancer cells to AF and olaparib treatment in p53 knock-in and knock-out models with varying p53 protein expression levels. Secondly, we determined the therapeutic range for synergistic cytotoxicity between AF and olaparib and elucidated the underlying molecular cell death mechanisms. Lastly, we evaluated the effectiveness of the combination strategy in a murine 344SQ 3D spheroid and syngeneic in vivo lung cancer model. We demonstrated that high concentrations of AF and olaparib synergistically induced cytotoxicity in NSCLC and PDAC cell lines with low levels of mutant p53 protein that were initially more resistant to AF. The aurola combination also led to the highest accumulation of ROS, which resulted in ROS-dependent cytotoxicity of mutant p53 NSCLC cells through distinct types of cell death, including caspase-3/7-dependent apoptosis, inhibited by Z-VAD-FMK, and lipid peroxidation-dependent ferroptosis, inhibited by ferrostatin-1 and alpha-tocopherol. High concentrations of both compounds were also needed to obtain a synergistic cytotoxic effect in 3D spheroids of the murine lung adenocarcinoma cell line 344SQ, which was interestingly absent in 2D. This cell line was used in a syngeneic mouse model in which the oral administration of aurola significantly delayed the growth of mutant p53 344SQ tumors in 129S2/SvPasCrl mice, while either agent alone had no effect. In addition, RNA sequencing results revealed that AF- and aurola-treated 344SQ tumors were negatively enriched for immune-related gene sets, which is in accordance with AF’s anti-inflammatory function as an anti-rheumatic drug. Only 344SQ tumors treated with aurola showed the downregulation of genes related to the cell cycle, potentially explaining the growth inhibitory effect of aurola since no apoptosis-related gene sets were enriched. Overall, this novel combination strategy of oxidative stress induction (AF) with PARP inhibition (olaparib) could be a promising treatment for mutant p53 cancers, although high concentrations of both compounds need to be reached to obtain a substantial cytotoxic effect.

The natural killer cell immunotherapy platform: an overview of the landscape of clinical trials in liquid and solid tumors

The translation of natural killer (NK) cells to the treatment of malignant disease has made significant progress in the last few decades. With a variety of available sources and improvements in both in vitro and in vivo NK cell expansion, the NK cell immunotherapy platform has come into its own. The enormous effort continues to further optimize this platform, including ways to enhance NK cell persistence, trafficking to the tumor microenvironment, and cytotoxicity. As this effort bears fruit, it is translated into a plethora of clinical trials in patients with advanced malignancies. The adoptive transfer of NK cells, either as a standalone therapy or in combination with other immunotherapies, has been applied for the treatment of both liquid and solid tumors, with numerous early-phase trials showing promising results. This review aims to summarize the key advantages of NK cell immunotherapy, highlight several of the current approaches being taken for its optimization, and give an overview of the landscape of clinical trials translating this platform into clinic.

Targeting tumor-associated macrophages for successful immunotherapy of ovarian carcinoma

Epithelial ovarian cancer (EOC) is among the top five causes of cancer-related death in women, largely reflecting early, prediagnosis dissemination of malignant cells to the peritoneum. Despite improvements in medical therapies, particularly with the implementation of novel drugs targeting homologous recombination deficiency, the survival rates of patients with EOC remain low. Unlike other neoplasms, EOC remains relatively insensitive to immune checkpoint inhibitors, which is correlated with a tumor microenvironment (TME) characterized by poor infiltration by immune cells and active immunosuppression dominated by immune components with tumor-promoting properties, especially tumor-associated macrophages (TAMs). In recent years, TAMs have attracted interest as potential therapeutic targets by seeking to reverse the immunosuppression in the TME and enhance the clinical efficacy of immunotherapy. Here, we review the key biological features of TAMs that affect tumor progression and their relevance as potential targets for treating EOC. We especially focus on the therapies that might modulate the recruitment, polarization, survival, and functional properties of TAMs in the TME of EOC that can be harnessed to develop superior combinatorial regimens with immunotherapy for the clinical care of patients with EOC.

Role of PARP Inhibitors in Cancer Immunotherapy: Potential Friends to Immune Activating Molecules and Foes to Immune Checkpoints

Poly (ADP-ribose) polymerase (PARP) inhibitors (PARPi) induce cytotoxic effects as single agents in tumors characterized by defective repair of DNA double-strand breaks deriving from BRCA1/2 mutations or other abnormalities in genes associated with homologous recombination. Preclinical studies have shown that PARPi-induced DNA damage may affect the tumor immune microenvironment and immune-mediated anti-tumor response through several mechanisms. In particular, increased DNA damage has been shown to induce the activation of type I interferon pathway and up-regulation of PD-L1 expression in cancer cells, which can both enhance sensitivity to Immune Checkpoint Inhibitors (ICIs). Despite the recent approval of ICIs for a number of advanced cancer types based on their ability to reinvigorate T-cell-mediated antitumor immune responses, a consistent percentage of treated patients fail to respond, strongly encouraging the identification of combination therapies to overcome resistance. In the present review, we analyzed both established and unexplored mechanisms that may be elicited by PARPi, supporting immune reactivation and their potential synergism with currently used ICIs. This analysis may indicate novel and possibly patient-specific immune features that might represent new pharmacological targets of PARPi, potentially leading to the identification of predictive biomarkers of response to their combination with ICIs.

Anti-cancer immune responses to DNA damage response inhibitors: Molecular mechanisms and progress toward clinical translation

DNA damage response inhibitors are widely used anti-cancer agents that have potent activity against tumor cells with deficiencies in various DNA damage response proteins such as BRCA1/2. Inhibition of other proteins in this pathway including PARP, DNA-PK, WEE1, CHK1/2, ATR, or ATM can sensitize cancer cells to radiotherapy and chemotherapy, and such combinations are currently being tested in clinical trials for treatment of many malignancies including breast, ovarian, rectal, and lung cancer. Unrepaired DNA damage induced by DNA damage response inhibitors alone or in combination with radio- or chemotherapy has a direct cytotoxic effect on cancer cells and can also engage anti-cancer innate and adaptive immune responses. DNA damage-induced immune stimulation occurs by a variety of mechanisms including by the cGAS/STING pathway, STAT1 and downstream TRAIL pathway activation, and direct immune cell activation. Whether or not the relative contribution of these mechanisms varies after treatment with different DNA damage response inhibitors or across cancers with different genetic aberrations in DNA damage response enzymes is not well-characterized, limiting the design of optimal combinations with radio- and chemotherapy. Here, we review how the inhibition of key DNA damage response enzymes including PARP, DNA-PK, WEE1, CHK1/2, ATR, and ATM induces innate and adaptive immune responses alone or in combination with radiotherapy, chemotherapy, and/or immunotherapy. We also discuss current progress in the clinical translation of immunostimulatory DNA-damaging treatment regimens and necessary future directions to optimize the immune-sensitizing potential of DNA damage response inhibitors.

Assessment of Postvaccination Neutralizing Antibodies Response against SARS-CoV-2 in Cancer Patients under Treatment with Targeted Agents

The administration of a third dose of a vaccine against SARS-CoV-2 has increased protection against disease transmission and severity. However, the kinetics of neutralizing antibodies against the virus has been poorly studied in cancer patients under targeted therapies. Baseline characteristics and levels of neutralizing antibodies at specific timepoints after vaccination were compared between patients suffering from breast, ovarian or prostate cancer and healthy individuals. Breast cancer patients were treated with cyclin D kinase 4/6 inhibitors and hormonal therapy, ovarian cancer patients were treated with poly (ADP-ribose) polymerase inhibitors and prostate cancer patients were treated with an androgen receptor targeted agent. Levels of neutralizing antibodies were significantly lower in cancer patients compared to healthy individuals at all timepoints. Antibodies’ titers declined over time in both groups but remained above protective levels (>50%) at 6 months after the administration of the second dose. The administration of a third dose increased neutralizing antibodies’ levels in both groups. The titers of protective against SARS-CoV-2 antibodies wane over time and increase after a third dose in cancer patients under treatment.

Clinical use of PARP inhibitor in recurrent uterine leiomyosarcoma with presence of a somatic BRCA2 mutation

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This report reiterates the aggressive nature of uLMS and introduces the novel use of PARPi in recurrent disease.

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NGS should be performed to identify functional BRCA1/2 loss in uLMS as PARPi may be a potential targeted therapy.

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PARPi are effective in tumor cells that lack BRCA1/2 tumor suppressor proteins by way of synthetic lethality.

Uterine leiomyosarcoma (uLMS) is an aggressive mesenchymal tumor associated with a poor prognosis. Research demonstrates that PARP inhibitors (PARPi) improve disease-stable survival in patients with somatic BRCA1/2 mutations through the process of synthetic lethality. Therefore, PARPi’s may have a role in treating gynecologic malignancies with deleterious BRCA1/2 mutations. This patient is a 50-year-old female with a history of stage IB uterine leiomyosarcoma, complicated by recurrence along the vaginal cuff and metastases to the lungs. A somatic BRCA2 mutation was identified, and the patient was started on Olaparib for treatment of recurrent disease. The patient has now been disease free for two years. We recommend next generation sequencing be performed to identify functional BRCA1/2 loss in uLMS as PARPi may be a potential targeted therapy for uLMS.

Evaluation of Treatment With Talazoparib and Avelumab in Patients With Recurrent Mismatch Repair Proficient Endometrial Cancer

Question

Is treatment with combined polyadenosine diphosphate-ribose polymerase and immune checkpoint inhibition active and safe in patients with recurrent mismatch repair proficient endometrial cancer (MMRP EC)?

Findings

In this single-arm, phase 2, 2-stage, nonrandomized clinical trial of treatment with avelumab and talazoparib in recurrent MMRP EC that included 35 patients, the confirmed objective response rate was 11.4%, and the progression-free survival at 6 months rate was 22.9%. No patients discontinued therapy because of toxic effects, and immunogenomic profiling provided insights into subsets of patients who may derive benefit from this combination.

Meaning

These study findings suggest that treatment with avelumab and talazoparib has a favorable toxic effects profile and support further investigation in certain subsets of patients with recurrent MMRP EC.

Importance

Although the activity of pembrolizumab and lenvatinib (the only US Food and Drug Administration–approved immunotherapy for mismatch repair proficient endometrial cancer [MMRP EC]) is compelling, there are no biomarkers of response and most patients do not tolerate, do not respond to, or develop resistance to this regimen, highlighting the need for additional, potentially biomarker-driven therapeutic approaches for patients with recurrent MMRP EC.

Objective

To assess the potential positive outcomes and safety of the combination of the polyadenosine diphosphate-ribose polymerase inhibitor talazoparib and the programmed cell death ligand 1 (PD-L1) inhibitor avelumab in recurrent MMRP EC.

Design, Settings, and Participants

This investigator-initiated, open-label, single-arm, 2-stage, phase 2 study nonrandomized controlled trial patients at 4 institutions in the US. Key eligibility criteria included measurable disease, unlimited prior therapies, and all endometrial cancer histologies.

Interventions

Talazoparib, 1 mg, orally, daily, and avelumab, 10 mg/kg, intravenously, every 2 weeks, were administered until disease progression or unacceptable toxic effects.

Main Outcomes and Measures

Statistical considerations were developed for 2 coprimary objectives of objective response rate and rate of progression-free survival at 6 months, with a 2-stage design that allowed for early discontinuation for futility. Prespecified exploratory objectives included the association of immunogenomic features (determined by targeted-panel next-generation sequencing and immunohistochemistry) with activity.

Results

Thirty-five female patients (mean [SD] age, 67.9 [8.41] years) received protocol therapy; 9 (25.7%) derived clinical benefit after meeting at least 1 of the 2 coprimary end points. Four patients (11.4%) exhibited confirmed objective response rates (4 partial responses), and 8 (22.9%) survived progression free at 6 months. The most common grade 3 and 4 treatment-related toxic effects were anemia (16 [46%]), thrombocytopenia (10 [29%]), and neutropenia (4 [11%]); no patient discontinued receipt of therapy because of toxic effects. Tumors with homologous recombination repair alterations were associated with clinical benefit from treatment with avelumab and talazoparib. Tumor mutational burden, tumor-infiltrating lymphocytes, and PD-L1 status were not associated with clinical benefit.

Conclusions and Relevance

The results of this nonrandomized controlled trial suggest that treatment with avelumab and talazoparib demonstrated a favorable toxic effect profile and met the predetermined criteria to be considered worthy of further evaluation in MMRP EC. Immunogenomic profiling provided insights that may inform ongoing and future studies of polyadenosine diphosphate-ribose polymerase and PD-L1 inhibitor combinations in endometrial cancer.

Trial Registration

ClinicalTrials.gov Identifier: NCT02912572

Case Report: Sustained complete remission on combination therapy with olaparib and pembrolizumab in BRCA2-mutated and PD-L1-positive metastatic cholangiocarcinoma after platinum derivate

Cholangiocarcinoma (CCA) still has a poor prognosis and remains a major therapeutic challenge. When curative resection is not possible, palliative systemic chemotherapy with gemcitabine and platinum derivate as first line followed by a 5-FU doublet combination as second line is the standard therapy. Recently, targeted therapy and immunotherapy have rapidly emerged as personalized therapeutic approaches requiring previous tumor sequencing and molecular profiling. BRCA mutations are well-characterized targets for poly (ADP-ribose) polymerase inhibitors (PARPi). However, BRCA gene mutations in CCA are rare and few data of PARPi in the treatment of CCA are available. Immunotherapy with programmed death receptor-1 (PD-1) has been shown to be effective in combination with chemotherapy or in PD-L1-positive CCA. However, data from immunotherapy combined with targeted therapy, including PARPi, are lacking. In this report, we present the case of a male patient with PD-L1-positive and BRCA2-mutated metastatic intrahepatic cholangiocarcinoma, who was treated with a combined therapy with PARP (PARPi), olaparib, and a PD-1 antibody, pembrolizumab, as second-line therapy after gemcitabine/platinum derivate failure. Combined therapy was able to induce a long-lasting complete remission for over 15 months. The combined therapy was feasible and well tolerated. Only mild anemia and immune-related thyroiditis were observed, which were easily manageable and did not result in discontinuation of olaparib and pembrolizumab.

A Novel PARP Inhibitor YHP-836 For the Treatment of BRCA-Deficiency Cancers

PARP inhibitors have clinically demonstrated good antitumor activity in patients with BRCA mutations. Here, we described YHP-836, a novel PARP inhibitor, YHP-836 demonstrated excellent inhibitory activity for both PARP1 and PARP2 enzymes. It also allosterically regulated PARP1 and PARP2 via DNA trapping. YHP-836 showed cytotoxicity in tumor cell lines with BRCA mutations and induced cell cycle arrest in the G2/M phase. YHP-836 also sensitized tumor cells to chemotherapy agents in vitro. Oral administration of YHP-836 elicited remarkable antitumor activity either as a single agent or in combination with chemotherapy agents in vivo. These results indicated that YHP-836 is a well-defined PARP inhibitor.

The Interplay between PARP Inhibitors and Immunotherapy in Ovarian Cancer: The Rationale behind a New Combination Therapy

Ovarian cancer (OC) has a high impact on morbidity and mortality in the female population. Survival is modest after platinum progression. Therefore, the search for new therapeutic strategies is of utmost importance. BRCA mutations and HR-deficiency occur in around 50% of OC, leading to increased response and survival after Poly (ADP-ribose) polymerase inhibitors (PARPis) administration. PARPis represent a breakthrough for OC therapy, with three different agents approved. On the contrary, immune checkpoint inhibitors (ICIs), another breakthrough therapy for many solid tumors, led to modest results in OC, without clinical approvals and even withdrawal of clinical trials. Therefore, combinations aiming to overcome resistance mechanisms have become of great interest. Recently, PARPis have been evidenced to modulate tumor microenvironment at the molecular and cellular level, potentially enhancing ICIs responsiveness. This represents the rationale for the combined administration of PARPis and ICIs. Our review ought to summarize the preclinical and translational features that support the contemporary administration of these two drug classes, the clinical trials conducted so far, and future directions with ongoing studies.

CXCL9 inhibits tumour growth and drives anti-PD-L1 therapy in ovarian cancer

Background

Response to immune checkpoint blockade (ICB) in ovarian cancer remains disappointing. Several studies have identified the chemokine CXCL9 as a robust prognosticator of improved survival in ovarian cancer and a characteristic of the immunoreactive subtype, which predicts ICB response. However, the function of CXCL9 in ovarian cancer has been poorly studied.

Methods

Impact of Cxcl9 overexpression in the murine ID8-Trp53^−/− and ID8-Trp53^−/–Brca2^−/− ovarian cancer models on survival, cellular immune composition, PD-L1 expression and anti-PD-L1 therapy. CXCL9 expression analysis in ovarian cancer subtypes and correlation to reported ICB response.

Results

CXCL9 overexpression resulted in T-cell accumulation, delayed ascites formation and improved survival, which was dependent on adaptive immune function. In the ICB-resistant mouse model, the chemokine was sufficient to enable a successful anti-PD-L1 therapy. In contrast, these effects were abrogated in Brca2-deficient tumours, most likely due to an already high intrinsic chemokine expression. Finally, in ovarian cancer patients, the clear-cell subtype, known to respond best to ICB, displayed a significantly higher proportion of CXCL9^high tumours than the other subtypes.

Conclusions

CXCL9 is a driver of successful ICB in preclinical ovarian cancer. Besides being a feasible predictive biomarker, CXCL9-inducing agents thus represent attractive combination partners to improve ICB in this cancer entity.

Basal expression of RAD51 foci predicts olaparib response in patient-derived ovarian cancer xenografts

BACKGROUND

The search for biomarkers to evaluate ovarian cancer (OC) homologous recombination (HR) function and predict the response to therapy is an urgent clinical need to improve the selection of patients who could benefit from platinum- and olaparib (poly-ADP ribose polymerase inhibitors, PARPi)-based therapies.

METHODS

We used a large collection of OC patient-derived xenografts (PDXs) (n = 47) and evaluated their HR status based on BRCA1/2 mutations, BRCA1 promoter methylation and the HRDetect score. RAD51 foci were quantified in formalin-fixed, paraffin-embedded untreated tumour specimens by immunofluorescence and the messenger RNA expression of 21 DNA repair genes by real-time PCR.

RESULTS

Tumour HR deficiency predicted both platinum and olaparib responses. The basal level of RAD51 foci evaluated in geminin-positive/replicating cells strongly inversely correlated with olaparib response (p = 0.011); in particular, the lower the foci score, the greater the sensitivity to olaparib, while low RAD51 foci score seems to associate with platinum activity.

CONCLUSIONS

The basal RAD51 foci score is a candidate predictive biomarker of olaparib response in OC patients as it can be easily translatable in a clinical setting. Moreover, the findings corroborate the importance of OC-PDXs as a reliable tool to identify and validate biomarkers of response to therapy.

Current Treatments and New Possible Complementary Therapies for Epithelial Ovarian Cancer

Epithelial ovarian cancer (EOC) is one of the deadliest gynaecological malignancies. The late diagnosis is frequent due to the absence of specific symptomatology and the molecular complexity of the disease, which includes a high angiogenesis potential. The first-line treatment is based on optimal debulking surgery following chemotherapy with platinum/gemcitabine and taxane compounds. During the last years, anti-angiogenic therapy and poly adenosine diphosphate-ribose polymerases (PARP)-inhibitors were introduced in therapeutic schemes. Several studies have shown that these drugs increase the progression-free survival and overall survival of patients with ovarian cancer, but the identification of patients who have the greatest benefits is still under investigation. In the present review, we discuss about the molecular characteristics of the disease, the recent evidence of approved treatments and the new possible complementary approaches, focusing on drug repurposing, non-coding RNAs, and nanomedicine as a new method for drug delivery.

The developing landscape of combinatorial therapies of immune checkpoint blockade with DNA damage repair inhibitors for the treatment of breast and ovarian cancers

The use of immune checkpoint blockade (ICB) using antibodies against programmed death receptor (PD)-1, PD ligand (PD-L)-1, and cytotoxic T-lymphocyte antigen 4 (CTLA-4) has redefined the therapeutic landscape in solid tumors, including skin, lung, bladder, liver, renal, and breast tumors. However, overall response rates to ICB therapy remain limited in PD-L1-negative patients. Thus, rational and effective combination therapies will be needed to address ICB treatment resistance in these patients, as well as in PD-L1-positive patients who have progressed under ICB treatment. DNA damage repair inhibitors (DDRis) may activate T-cell responses and trigger inflammatory cytokines release and eventually immunogenic cancer cell death by amplifying DNA damage and generating immunogenic neoantigens, especially in DDR-defective tumors. DDRi may also lead to adaptive PD-L1 upregulation, providing a rationale for PD-L1/PD-1 blockade. Thus, based on preclinical evidence of efficacy and no significant overlapping toxicity, some ICB/DDRi combinations have rapidly progressed to clinical testing in breast and ovarian cancers. Here, we summarize the available clinical data on the combination of ICB with DDRi agents for treating breast and ovarian cancers and discuss the mechanisms of action and other lessons learned from translational studies conducted to date. We also review potential biomarkers to select patients most likely to respond to ICB/DDRi combination therapy.

The relationship between the efficacy of talazoparib and the functional toll-like receptors 3 and 9 in triple negative breast cancer

Poly (ADP-ribose) polymerase (PARP) inhibitors (PARPi) induce cell death by inhibiting the repair of DNA strand breaks binding to PARP and regulate immune cells functions. Toll-like receptors (TLRs) mediate the tumor microenvironment through the modulation of proinflammatory cytokines and chemokines. In this context, this study addressed the relationship between the efficacy of talazoparib (TAL) as a PARPi and the activation of TLR3 or TLR9 by Polyinosinic:polycytidylic acid (Poly I:C) or CpG oligodeoxynucleotides (CpG-ODN) stimulation, respectively in triple negative breast cancer (TNBC). TAL alone and the combination of TAL with Poly I:C or CpG-ODN induced cell death were analyzed by water-soluble tetrazolium salt 1 (WST-1), Annexin V analysis, acridine orange staining and mRNA levels of caspase-3 and caspase-8 in HCC1937 and HCC1937-R (TAL resistant) TNBC cells. Additionally, the expression of TLR3, TLR9 and interferon regulatory factor 7 (IRF7) was observed with immunofluorescence staining and western blot analysis. Our findings showed that TAL induced TLR3 and TLR9 activation and acted in synergy with TLR3 and TLR9 agonists in TNBC cells. The stimulation of TLR3 or TLR9 and TAL treatment caused significantly more apoptosis in TNBC cells through the over-expression of caspase-3 and caspase-8. Additionally, TAL combined with Poly I:C or CpG-ODN more increased TLR3, TLR9 and IRF7 protein levels in HCC1937 cells and treatment with TAL and Poly I:C had greater potential for overcoming TAL resistance. In conclusion, the combination of PARPi with TLR agonists may be a new therapeutic combined strategy for the effective immunotherapy of TNBC.

Immunology and Immune Checkpoint Inhibition in Ovarian Cancer - Current Aspects

In the last decade immunotherapies such as immune checkpoint blockade (ICB) against the PD-1/PD-L1 system have revolutionised the treatment of numerous entities. To date, ovarian cancer has benefited very little from this success story. Possible causes include a rather low mutational burden compared to other tumour types, inadequate presentation of (neo-)antigens, and increased infiltration with immunosuppressive immune cells such as regulatory T cells and tumour-associated macrophages. In the clinical trials completed to date, the response rates to PD-1/PD-L1 checkpoint inhibitors have therefore been disappointingly low as well, although isolated long-term remissions have also been observed in ovarian cancer. The task now is to find suitable predictive biomarkers as well as to identify combination partners for ICB therapy that can increase the immunogenicity of ovarian cancer or overcome immunosuppressive resistance mechanisms. This paper provides an overview of the immune milieu in ovarian cancer, its impact on the effect of ICB, and summarises the clinical trial data available to date on ICB in ovarian cancer.

Immunological Response to COVID-19 Vaccination in Ovarian Cancer Patients Receiving PARP Inhibitors

Objective: Vaccination for SARS-CoV-2 provides significant protection against the infection in the general population. However, limited data exist for cancer patients under systemic therapy. Methods: In this cohort, we prospectively enrolled cancer patients treated with PARPi as well as healthy volunteers in order to study the kinetics of anti-SARS-CoV-2 antibodies (NAbs) after COVID-19 vaccination. Baseline demographics, co-morbidities, and NAb levels were compared between the two groups. Results: The results of the cohort of 36 patients receiving PARP inhibitors are presented here. Despite no new safety issues being noticed, their levels of SARS-CoV-2 neutralizing antibodies were significantly lower in comparison to matched healthy volunteers up to day 30 after the second dose. Conclusions: These results suggest that maintaining precautions against COVID-19 is essential for cancer patients and should be taken into consideration for the patients under treatment, while further exploration is needed to reduce the uncertainty of SARS-CoV-2 immunity among cancer patients under treatment.

Reduced humoral immune response after BNT162b2 coronavirus disease 2019 messenger RNA vaccination in cancer patients under antineoplastic treatment

Background

Cancer patients are at a higher risk of developing severe coronavirus disease 2019 (COVID-19). However, the safety and efficacy of COVID-19 vaccination in cancer patients undergoing treatment remain unclear.

Patients and methods

In this interventional prospective multicohort study, priming and booster doses of the BNT162b2 COVID-19 vaccine were administered 21 days apart to solid tumor patients receiving chemotherapy, immunotherapy, targeted or hormonal therapy, and patients with a hematologic malignancy receiving rituximab or after allogeneic hematopoietic stem cell transplantation. Vaccine safety and efficacy (until 3 months post-booster) were assessed. Anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) receptor-binding domain (RBD) antibody levels were followed over time (until 28 days after the booster) and in vitro SARS-CoV-2 50% neutralization titers (NT50) toward the wild-type Wuhan strain were analyzed 28 days after the booster.

Results

Local and systemic adverse events (AEs) were mostly mild to moderate (only 1%-3% of patients experienced severe AEs). Local, but not systemic, AEs occurred more frequently after the booster dose. Twenty-eight days after the booster vaccination of 197 cancer patients, RBD-binding antibody titers and NT50 were lower in the chemotherapy group {234.05 IU/ml [95% confidence interval (CI) 122.10-448.66] and 24.54 (95% CI 14.50-41.52), respectively} compared with healthy individuals [1844.93 IU/ml (95% CI 1383.57-2460.14) and 122.63 (95% CI 76.85-195.67), respectively], irrespective of timing of vaccination during chemotherapy cycles. Extremely low antibody responses were seen in hematology patients receiving rituximab; only two patients had RBD-binding antibody titers necessary for 50% protection against symptomatic SARS-CoV-2 infection (<200 IU/ml) and only one had NT50 above the limit of detection. During the study period, five cancer patients tested positive for SARS-CoV-2 infection, including a case of severe COVID-19 in a patient receiving rituximab, resulting in a 2-week hospital admission.

Conclusion

The BNT162b2 vaccine is well-tolerated in cancer patients under active treatment. However, the antibody response of immunized cancer patients was delayed and diminished, mainly in patients receiving chemotherapy or rituximab, resulting in breakthrough infections.

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The BNT162b2 vaccine is well-tolerated in cancer patients, including patients under immunotherapy.

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Full BNT162b2 vaccination results in a blunted humoral immune response in cancer patients under active treatment.

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The humoral immune response after BNT162b2 vaccination varies between different antineoplastic treatments.

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Two doses of BNT162b2 vaccination may insufficiently protect patients receiving chemotherapy or rituximab against SARS-CoV-2.

NLR and BRCA mutational status in patients with high grade serous advanced ovarian cancer

Laboratory-markers of the systemic inflammatory-response, such as neutrophil/lymphocyte-ratio (NLR) have been studied as prognostic factors in several tumors but in OC-patients their role is still controversial and no data about the possible correlation with the BRCA-status has been ever reported. We consecutively enrolled a series of 397 newly diagnosed high-grade serous-advanced OC-patients. All patients were tested for BRCA-mutational-status and blood-parameters have been collected 48 h before staging-surgery. A significant correlation of NLR with disease distribution (p < 0.005) was found and patients with NLR < 4 underwent primary-debulking-surgery more frequently (p-value 0.001), with a lower surgical-complexity-score (p-value 0.002). Regarding survival-data, patients with NLR < 4 had a significant 7-month increase in mPFS (26 vs 19 months, p = 0.009); focusing on the BRCA-status, among both BRCA-mutated and BRCA-wild type patients, those with lower NLR had a significantly prolonged mPFS compared to patients with NLR > 4 (BRCA-mutated: 35 vs 23 months, p = 0.03; BRCA-wt: 19 vs 16 months, p = 0.05). At multivariate-analysis, independent factors of prolonged PFS were BRCA mutational status, having received complete cytoreduction and NLR < 4. Also, the strongest predictors of longer OS were BRCA-mutational status, having received complete cytoreductive surgery, NLR < 4 and age. NLR is confirmed to be a prognostic marker in OC-patients and it seems unrelated with BRCA-mutational status.

Poly (ADP-ribose) polymerase inhibitors in solid tumours: Systematic review and meta-analysis

BACKGROUND

Poly (ADP-ribose) polymerase-inhibitors (PARPis) showed antitumour activity in BRCA1/2-mutated cancers, with more heterogeneous outcomes in tumours harbouring mutations that impair other genes involved in the DNA homologous recombination repair (HRR) or wild-type (wt).

METHODS

We conducted a systematic review and meta-analysis to better assess the role of PARPis in the treatment of metastatic solid tumours, with and without BRCA1/2 mutations. The primary end-point was progression-free survival (PFS). The secondary end-points were overall response rate (ORR) and overall survival (OS). A random-effects model was applied.

RESULTS

Twenty-nine studies (8,839 patients) were included. PFS was significantly improved (hazard ratio [HR]: 0.59, 95% confidence interval [CI]: 0.51-0.68, p < 0.001), without being affected by BRCA mutational status (p = 0.65). Significant subgroup differences were observed with regard to the tumour site (p = 0.001), line of therapy (p = 0.002), control arm (p < 0.001), type of PARPi (p < 0.001) and trials' phase (p = 0.006). PARPis were associated with ORR (relative risk: 1.35, 95% CI: 1.16-1.56, p < 0.001), with significant subgroup differences observed with regard to treatment line (p = 0.03), control arm (p = 0.04) and PARPis (p < 0.001) and independent of mutational status (p = 0.44), tumour site (p = 0.86) and trials' phase (p = 0.09). OS was significantly improved by PARPis (HR: 0.86, 95% CI: 0.80-0.92, p < 0.001), regardless of mutational status (p = 0.57), tumour site (p = 0.82), treatment line (p = 0.22), control arm (p = 0.21), PARPis (p = 0.30) and trials' phase (p = 0.26). Finally, an exploratory subgroup analysis showed a significant PFS improvement (HR: 0.51, 95% CI: 0.43-0.60, p < 0.001) with PARPis in BRCA-wt/HRR-deficient tumours.

CONCLUSION

Our results confirm the efficacy of already approved PARPi-based treatments in BRCA1/2-mutant solid tumours, support their role also in BRCA-independent HRR-deficient tumours and suggest a potentially broader efficacy in some wt tumours, perhaps with appropriate therapeutic partners. Prospective studies are warranted.