Research progress of PARP inhibitor monotherapy and combination therapy for endometrial cancer

The dysregulation of PARP9 expression is linked to apoptosis and DNA damage in gastric cancer cells

BACKGROUND

Gastric cancer (GC) is a highly malignant gastrointestinal tumor characterized by difficult early diagnosis and poor prognosis. Therefore, it is imperative to explore potential therapeutic targets for gastric cancer. PARP9 is abnormally expressed in a variety of tumors and is associated with tumor cell apoptosis and DNA damage. However, its relationship with GC has not been fully studied.

METHODS

The expression and prognostic significance of PARP9 in gastric cancer (GC) were examined using bioinformatics approaches. Cell lines with either knockdown or overexpression of PARP9 were established through lentiviral transduction, and the role of PARP9 in the malignant phenotypes of GC cells was validated via CCK8 assays, wound healing assays, clonogenic assays, and Transwell migration experiments. Finally, alterations in downstream targets and signaling pathways following changes in PARP9 expression were analyzed through RNA sequencing.

RESULTS

PARP9 is highly expressed in GC tissues and is associated with poor prognosis. PARP9 knockdown can significantly inhibit the proliferation, invasion and migration of GC cells, and increase the apoptosis and DNA damage of GC cells. The therapeutic process of PARP9 in GC may be realized by synergistic interaction with SOX6 through MAPK signaling pathway.

CONCLUSIONS

Our study reveals a potential link between PARP9 and GC, providing a new target for the treatment of GC.

Clinical characteristics and genomic profiling of outpatients with endometrial cancer at a Chinese tertiary cancer center

OBJECTIVE

Endometrial cancer is stepping into the era of precision therapy. Genomic test is recommended for newly diagnostic patients. However, outpatients displayed more complex characteristics. Here, we elucidated the clinical characteristics and genomic profiling of outpatients with endometrial cancer at our institution.

METHODS

Between 2018 and 2023, 68 endometrial cancer received genomic tests at outpatient department of Fudan University Shanghai Cancer Center. Data, including age, pathological histology, FIGO stage and treatment strategy were collected. Germline mutations, molecular subtypes and other somatic mutations were also summarized.

RESULTS

Overall, 72.1% (49/68) of patients receive genomic tests at primary diagnosis, while 27.9% (19/68) of patients received tests at recurrence. Nine patients had deleterious germline mutations, including BRCA1(2), MLH1(1), MSH2(2, including one with co-mutation of RAD50), MSH6(2), FANCA(1), MUTYH(1). Molecular subtypes were recognized among 62 patients, as POLE super-mutation(4, 6.5%), MSI-H(7, 11.3%), CN-Low(36, 58.1%) and CN-High(15, 24.2%). Ten patients received anti-PD1 monotherapy or in combination with chemotherapy or anti-angiogenic therapy, with the duration of disease control of 1 to 35 months. The ORR rate was 30%, and six patients had stable disease. The median (range) follow-up time was 18(2-160) months. 23(33.8%) relapses were recorded, and CN-High subtype displayed worst PFS compared with other subtypes (P < 0.01). 6 deaths were reported including 2(5.6%) of CN-Low and 4(26.7%) of CN-High.

CONCLUSION

Outpatients department gathered a considerable proportion of recurrent patients with complex genomic features. Patients with worse prognosis could be well studied, and anti-PD1 therapy was a promising salvage therapy in the real world.

Overexpression of zinc finger DHHC-type containing 1 is associated with poor prognosis and cancer cell growth and metastasis in uterine corpus endometrial carcinoma

The zinc finger DHHC-type containing 1 (ZDHHC1) gene is implicated in the pathogenesis and progression of various malignant tumors, but its precise involvement in uterine corpus endometrial carcinoma (UCEC) remains unknown. Thus, this study investigated ZDHHC1 expression in UCEC using publicly available TCGA and Xena databases and elucidated the functions and mechanisms of the ZDHHC1 gene in UCEC progression using bioinformatics and in vitro experiments. The correlation between ZDHHC1 expression and prognosis, clinical features, immune cells, and RNA modifications of UCEC was evaluated using nomograms, correlation, ROC, and survival analyses. The impacts of ZDHHC1 overexpression on UCEC progression and mechanisms were explored with bioinformatics and in vitro experiments. Our study revealed that ZDHHC1 expression was significantly downregulated in UCEC and correlated with poor prognosis, cancer diagnosis, clinical stage, age, weight, body mass index, histological subtypes, residual tumor, tumor grade, and tumor invasion. Notably, Cox regression analysis and constructed nomograms showed that downregulated ZDHHC1 expression was a prognostic factor associated with poor prognosis in patients with UCEC. Conversely, above-normal ZDHHC1 expression inhibited the cell growth, cell cycle transition, migration, and invasion of UCEC cells, which may be related to the cell cycle, DNA replication, PI3K-AKT, and other pathways that promote tumor progression. Altered ZDHHC1 expression in UCEC was significantly associated with RNA modifications and the changes in cancer immune cell populations, such as CD56 bright NK cells, eosinophils, Th2 cells, and cell markers. In conclusion, considerably reduced ZDHHC1 expression in UCEC is associated with cancer cell growth, metastasis, poor prognosis, immune infiltration, and RNA modifications, revealing the promising potential of ZDHHC1 as a prognostic marker for UCEC.

Focusing on the role of protein kinase mTOR in endometrial physiology and pathology: insights for therapeutic interventions

The mammalian target of rapamycin (mTOR) is a serine/threonine protein kinase crucial for cellular differentiation, proliferation, and autophagy. It shows a complex role in the endometrium, influencing both normal and pathogenic conditions. mTOR promotes the growth and maturation of endometrial cells, enhancing endometrial receptivity and decidualization. However, it also contributes to the development of endometriosis (EMs) and endometrial cancer (EC), thus emerging as a therapeutic target for these conditions. In this review, we summarize recent research progress on the mTOR signalling pathway in the endometrium. This provides insights into female endometrial structure and function and guides the prevention and treatment of related diseases.

Targeting DNA Damage Repair and Immune Checkpoint Proteins for Optimizing the Treatment of Endometrial Cancer

The dependence of cancer cells on the DNA damage response (DDR) pathway for the repair of endogenous- or exogenous-factor-induced DNA damage has been extensively studied in various cancer types, including endometrial cancer (EC). Targeting one or more DNA damage repair protein with small molecules has shown encouraging treatment efficacy in preclinical and clinical models. However, the genes coding for DDR factors are rarely mutated in EC, limiting the utility of DDR inhibitors in this disease. In the current review, we recapitulate the functional role of the DNA repair system in the development and progression of cancer. Importantly, we discuss strategies that target DDR proteins, including PARP, CHK1 and WEE1, as monotherapies or in combination with cytotoxic agents in the treatment of EC and highlight the compounds currently being evaluated for their efficacy in EC in clinic. Recent studies indicate that the application of DNA damage agents in cancer cells leads to the activation of innate and adaptive immune responses; targeting immune checkpoint proteins could overcome the immune suppressive environment in tumors. We further summarize recently revolutionized immunotherapies that have been completed or are now being evaluated for their efficacy in advanced EC and propose future directions for the development of DDR-based cancer therapeutics in the treatment of EC.

Tumor Microenvironment CD8 T and Treg Cells-related Genes Signature Distinguishes Distinct Prognosis and Targeted Therapies Response in Endometrial Cancer

Although most endometrial cancer (EC) patients have a favorable prognosis, the overall survival (OS) of metastatic and recurrent EC could hardly be improved by the current chemoradiotherapy. We aimed to reveal the tumor microenvironment immune infiltration characteristics to elucidate the underlying mechanism of EC progression and guide clinical decisions. In the Cancer Genome Atlas (TCGA) cohort, Kaplan-Meier survival curves confirmed Tregs and CD8 T cells were prognosis-protective factors in OS of EC ( P <0.05). Weighted gene coexpression network analysis identified 2 gene modules closely correlated with Tregs and CD8 T-cell infiltration. We randomly split the TCGA EC cohort into the training and testing cohorts at a ratio of 7:3. An immune-related prognosis risk index (IRPRI), including NR3C1, E2F1, OTOG, TTK, PPP1R16B, and FOXP3, was established by univariate, Least Absolute Shrinkage and Selection Operator, and multivariate Cox regression with area under the curve >0.67. Distinct clinical, immune, and mutation characteristics existed between IRPRI groups by multiomics analysis. Cell proliferation and DNA damage repair-related pathways were activated, and immune-related pathways were inactivated in the IRPRI-high group. Furthermore, patients in the IRPRI-high group had lower tumor mutation burden, programmed death-ligand 1 expression, and Tumor Immune Dysfunction and Exclusion scores, indicating a poor response to immune checkpoint inhibitors therapy ( P <0.05), which was also validated in the TCGA testing cohort and independent cohorts, GSE78200, GSE115821, and GSE168204. Also, the higher mutation frequencies of BRCA1, BRCA2, and genes enrolled in homologous recombination repair in the IRPRI-low group predicted a good response to PARP inhibitors. Finally, a nomogram integrating the IRPRI group and prognosis significant clinicopathological factors for EC OS prediction was developed and validated with good discrimination and calibration.

Safety and Efficacy of the mTOR Inhibitor, Vistusertib, Combined With Anastrozole in Patients With Hormone Receptor-Positive Recurrent or Metastatic Endometrial Cancer: The VICTORIA Multicenter, Open-label, Phase 1/2 Randomized Clinical Trial

Importance

Endometrial cancer is often hormone-dependent and treated with aromatase inhibitors. The PI3K-AKT-mTOR pathway deregulation observed in endometrial cancer drives hormonal resistance, thus supporting the rationale of combining mTOR inhibitor with endocrine therapy.

Objective

To evaluate the safety and efficacy of vistusertib in combination with anastrozole in the treatment of women with hormone receptor-positive recurrent or metastatic endometrial cancer.

Design, Settings, and Participants

The VICTORIA study was a multicenter, open-label, randomized clinical trial that accrued 75 patients with hormone receptor-positive recurrent or metastatic endometrial cancer from 12 cancer centers in France in April 2016 to October 2019. After a safety run-in period, a Simon 2-stage design was used. Data analyses were performed from December 11, 2020, to March 11, 2021.

Interventions

Patients were randomized in a 2:1 ratio to oral vistusertib (125 mg twice daily 2 days per week) and oral anastrozole (1 mg daily) in the combination vistusertib with anastrozole arm (V+A arm) or oral anastrozole alone (A arm).

Main Outcomes and Measures

The primary end point was serious adverse events for the safety run-in period and progression-free rate at 8 weeks (8wk-PFR)-assessed with a blinded independent central review in phase 2. The secondary end points were objective response rate, duration of response, progression-free survival (PFS), overall survival, and incidence of adverse events.

Results

Of the 75 patients who were randomized, 73 (median [range] age, 69.5 [37-88] y; all female) were treated: V+A arm, 49 patients; A arm, 24 patients. In the V+A arm, the 8wk-PFR was 67.3% (unilateral 95% CI, 54.7%) and in the A arm, 39.1% (unilateral 95% CI, 22.2%). No significant serious adverse events were reported during the safety run-in period (n = 6 in V+A arm). The overall response rate was 24.5% (95% CI, 13.3%-38.9%) in the V+A arm vs 17.4% (95% CI, 5.0%-38.8%) in the A arm. With a median follow-up of 27.7 months, median PFS was 5.2 (95% CI, 3.4-8.9) in the V+A arm and 1.9 (95% CI, 1.6-8.9) months in the A arm. Fatigue, lymphopenia, hyperglycemia, and diarrhea were the most common (grade ≥2) adverse events associated with vistusertib.

Conclusions and Relevance

This multicenter, open-label, phase 1/2 randomized clinical trial demonstrated that adding vistusertib to anastrozole improved 8wk-PFR, overall response rate, and PFS for patients with endometrial cancer and had manageable adverse events. Identification of molecular subgroups would allow for more precise selection of patients who may be most likely to experience favorable outcomes.

Trial Registration

ClinicalTrials.gov Identifier: NCT02730923.

Blocking PARP activity with the inhibitor veliparib enhances radiotherapy sensitivity in endometrial carcinoma

OBJECTIVE

Our study aimed to investigate the potential clinical utility of a poly(ADP-ribose) polymerase (PARP) inhibitor, veliparib (ABT-888), as a radiosensitizer in the medication of endometrial carcinoma (EC).

METHODS

Human Ishikawa endometrial adenocarcinoma cells were treated with veliparib, radiotherapy (RT), or combination treatment. The viabilities, radiosensitivity enhancement ratio (sensitizer enhancement ratio (SER), and apoptosis of Ishikawa cells were, respectively, evaluated by Cell Counting Kit-8 (CCK-8), colony formation experiment, and flow cytometry. The tumor growth was assessed by xenograft mice models. Western blot assay investigated the expression of DNA damage and apoptosis-related proteins in vivo and in vitro.

RESULTS

Cell Counting Kit-8 revealed that the 10% inhibition concentration (IC₁₀ ) and 50% inhibition concentration (IC₅₀ ) values of veliparib-treated Ishikawa cells were 1.7 and 133.5 µM, respectively. The SER of veliparib combined with RT was 1.229 in vitro. Flow cytometry analysis results indicated that the apoptosis rate of the veliparib + RT group was markedly higher than that of the RT group in vitro (p < 0.05). Furthermore, in vivo data revealed that veliparib + RT treatment significantly decreased tumor growth compared with single treatments of veliparib or RT and with the control group (p < 0.05). Then western blot confirmed the levels of anti-phospho-histone (γH2AX), caspase-3, and B-cell lymphoma 2 (Bcl-2) associated protein X (Bax) were significantly higher in the veliparib + RT group, while the level of Bcl-2 was lower compared with that of the RT group (p < 0.05), both in vivo and in vitro.

CONCLUSION

Our results indicate that veliparib in combination with RT markedly improved the therapeutic efficiency in human endometrial carcinoma.