Movement of Poly-ADP Ribose (PARP) Inhibition into Frontline Treatment of Ovarian Cancer

Homologous Recombination Deficiency Score Determined by Genomic Instability in a Romanian Cohort

The Homologous Recombination Deficiency (HRD) Score, determined by evaluating genomic instability through the assessment of loss of heterozygosity (LOH), telomeric allelic imbalance (TAI), and large-scale state transitions (LST), serves as a crucial biomarker for identifying patients who might benefit from targeted therapies, such as PARP inhibitors (PARPi). This study aimed to investigate the efficacy of HRD testing in high-grade serous ovarian carcinoma, tubal, and peritoneal cancer patients who are negative for somatic BRCA1 and BRCA2 mutations and to evaluate the impact of HRD status on Bevacizumab and PARPi therapy response. A cohort of 100 Romanian female patients, aged 42-77, was initially selected. Among them, 30 patients had unsuitable samples for HRD testing due to insufficient tumor content or DNA integrity. Using the OncoScan C.N.V. platform, HRD testing was successfully performed on the remaining 70 patients, with 20 testing negative and 50 testing positive for HRD. Among the HRD-positive patients, 35 were eligible for and benefited from PARPi maintenance therapy, resulting in a median progression-free survival (PFS) increase from 4 months to 8.2 months. Our findings support the importance of HRD testing in ovarian cancer patients, demonstrating the potential therapeutic advantage of PARPi therapy in HRD-positive patients without somatic BRCA1/2 mutations.

PBK drives PARP inhibitor resistance through the TRIM37/NFκB axis in ovarian cancer

Resistance to PARP inhibitors (PARPi) remains a therapeutic challenge in ovarian cancer patients. PDZ-binding kinase (PBK) participates in the chemoresistance of many malignancies. However, the role of PBK in PARPi resistance of ovarian cancer is obscure. In the current study, we demonstrated that overexpression of PBK contributed to olaparib resistance in ovarian cancer cells. Knockdown of PBK sensitized olaparib-resistant SKOV3 cells to olaparib. Inhibition of PBK using a specific inhibitor enhanced the therapeutic efficiency of olaparib. Mechanically, PBK directly interacted with TRIM37 to promote its phosphorylation and nuclear translocation. which subsequently activates the NFκB pathway. Additionally, PBK enhanced olaparib resistance of ovarian cancer by regulating the NFκB/TRIM37 axis in vitro and in vivo. In conclusion, PBK confers ovarian cancer resistance to PARPi through activating the TRIM37-mediated NFκB pathway, and targeted inhibition of PBK provided the new therapy to improve PARPi treatment outcomes for ovarian cancer patients.

An enzyme implicated in tumor progression also helps cancers thwart a commonly used type of targeted drug therapy. Beihua Kong and colleagues from Shandong University, Jinan, China, showed how PDZ-binding kinase (PBK), an enzyme that promotes the proliferation and spread of cancer cells, activates a signaling pathway that renders tumors resistant to treatment with olaparib. This precision anti-cancer drug works by blocking a protein called PARP that normally helps cells repair damaged DNA. The researchers showed how PBK interacts with another protein to stimulate a transcription factor previously shown to reduce the effectiveness of radiation and chemotherapy. Blocking the activity of PBK, either pharmacologically or genetically, enhanced the sensitivity of ovarian cancer cells to olaparib. A similar drug strategy could help improve outcomes for cancer patients undergoing PARP inhibitor treatment.

Racial and ethnic enrollment disparities in clinical trials of poly(ADP-ribose) polymerase inhibitors for gynecologic cancers

OBJECTIVES

Disparities persist in the enrollment of racial/ethnic groups in clinical trials for ovarian cancers. We sought to analyze the enrollment rates of patients by race/ethnicity in phase II/III clinical trials involving poly(ADP-ribose) polymerase (PARP) inhibitors for ovarian cancers and compare these to the racial/ethnic prevalence of ovarian cancers in the United States.

METHODS

This study was a retrospective review of clinical trials registered with ClinicalTrials.gov. Studies included evaluated PARP inhibitors for the treatment of ovarian, fallopian tube, and primary peritoneal cancers. Enrollment rates for clinical trials were stratified by race/ethnicity and type of cancer. Enrollment fractions (EFs) were calculated using prevalence data from the Surveillance, Epidemiology, and End Results Program. Odds ratios (OR) and 95% confidence intervals (CI) were calculated to compare racial/ethnic group enrollment rates to Non-Hispanic (NH) White enrollment rates.

RESULTS

Forty-eight trials were identified, 15 of which met inclusion criteria. The EFs for included trials, were 1.5% for NH-White, 0.47% for NH-Black, 0.33% for Hispanic, and 2.38% for Asian/Pacific Islander. Patients who identified as NH-Black and Hispanic were significantly underrepresented compared to those who identified as NH-White (OR 0.23, 95% CI [0.18-0.29] and OR 0.3, 95% CI [0.25-0.38] respectively, p < 0.001).

CONCLUSIONS

NH-Black and Hispanic patients are significantly underrepresented in clinical trials evaluating PARP inhibitors for ovarian cancers compared to NH-White cohorts. Phase II/III trials assessing PARP inhibitors for ovarian cancers do not accurately represent the populations diagnosed with these malignancies. Enrollment strategies are needed to increase diversity in PARP inhibitor clinical trials for women's cancers.

DNA N6-Methyladenine (6mA) Modification Regulates Drug Resistance in Triple Negative Breast Cancer

Triple negative breast cancer (TNBC) is a subtype of breast cancer with strong aggressiveness and poor clinical treatment effect, accounting for about 10–20% of breast cancer cases. N(6)-methyldeoxyadenosine (6mA) is the most conservative DNA modification in prokaryotes and eukaryotes. It is widely found in bacteria and has such functions as DNA mismatch repair, chromosome separation and virulence regulation. We determined that 6mA was modified in TNBC cell line MDA-MB-231 and the TNBC tissue. Meanwhile, compared with normal tissues, the expression level of 6mA and its methylase N6AMT1 was significantly decreased in TNBC tissue. MDA-MB-231cells were cultured with 8μM Olaparib for 2 months to construct drug-resistant cell line 231-RO. It was found that the level of 6mA also increased significantly, and the expression of N6AMT1 or ALKBH1 could effectively influence the drug resistance. Subsequently, we found that LINP1 was highly expressed in 231-RO, which was involved in DNA repair, and the expression of LINP1 could be positively regulated by 6mA modification. LINP1 expression level is directly related to TNBC drug resistance. The above results indicate that 6mA may be a new biological marker of TNBC. Meanwhile, 6mA modification may be involved in the regulation of Olaparib resistance.

How to sequence treatment in relapsed ovarian cancer

Numerous disease- and patient-related factors must be considered when selecting systemic therapy for recurrent ovarian cancer. Anti-angiogenics (bevacizumab) and poly(ADP-ribose) polymerase inhibitors (olaparib, niraparib and rucaparib) have an important role as maintenance of platinum-based chemotherapy for recurrent disease and their use in the first-line setting of advanced-stage disease is becoming established. As previous exposure to none, one or both of these drug classes is integral to selecting next therapy, front-line use impacts on options available to treat recurrent disease. A key strategy to delay platinum resistance and improve prognosis of recurrent disease is to alternate treatments with different mechanisms of action. The multiple mechanisms of trabectedin and its complementarity with platinum allow intercalation between platinum regimens in potentially platinum-responsive patients with recurrent disease.