Assessment of homologous recombination deficiency (HRD) status is now essential for ovarian cancer patient management. The aim of our study was to analyze the influence of ethnic variations, tumor purity, and neoadjuvant chemotherapy (CT) on the determination of HRD scores as well as to evaluate feasibility of HRD testing with the Amoy HRD Focus Assay in routine clinical practice. The HRD status, including the BRCA status and genomic scar score (GSS), was analyzed in 452 ovarian cancer specimens. The successful rate of HRD testing was 86% (388/452). The BRCA mutational rate was 29% (114/388); 252 samples (65%) were classified as HRD-positive. Our data demonstrate the feasibility of internal HRD testing by the AmoyDx HRD Focus Panel for high-grade serous ovarian cancer (HGSOC), showing results similar to other methods. The HRD rate in the Russian population is very similar to those of other European populations, as is the BRCA mutation frequency. The most substantial contribution to HRD level diversity is testing criteria depending on intrahospital arrangements. The analysis shows that biallelic BRCA alterations had higher GSS compared with those with monoallelic inactivation, consistent with positive HRD status. The study indicates that grades 1–2 of the pathological response caused by chemotherapy affect HRD scores and suggests controlling for tumor purity of 40% or more as a critical factor for GSS measurement.

Homologous recombination repair deficiency (HRD) is involved in the development of high-grade serous ovarian carcinoma (HGSOC) and its elevated sensitivity to platinum-based chemotherapy. To investigate the heterogeneity of the HRD-positive HGSOC we evaluated the HRD status, including BRCA mutations, genomic scar score, and methylation status of BRCA1/2 genes in 352 HGSOC specimens. We then divided the HRD-positive cohort into three molecular subgroups, the BRCA mutation cohort (BRCA+), BRCA1 methylation cohort (Meth+), and the rest of the HRD+ cohort (HRD+BRCA-Meth-), and evaluated their first-line chemotherapy response, benefit from olaparib, and progression-free survival (PFS). HRD-positive status was detected in 65% (228/352) of samples. The first group, BRCA+, accounted for 45% (102/228) of HRD positive cases and showed the best outcome in platinum therapy (ORR 96%), the highest olaparib benefit (p = 0.006) and the highest median PFS (46 months). The frequency of the second cohort, Meth+, among HRD-positive patients was 23% (52/228). Patients with Meth+ HGSOC showed a significantly poorer outcome, with a median PFS of 19 months, a significantly lower ORR to platinum therapy (84%) and a modest, but not significant, benefit from olaparib maintenance. The third HRD+BRCA-Meth- group accounted for 32% (74/228) of HRD-positive patients and showed an ORR to platinum therapy similar to that of the BRCA+ group (90%), a higher, but not statistically significant, benefit from olaparib and a median PFS of 23 months. In conclusion, Meth+ subgroup had poor outcomes in terms of chemotherapy response, olaparib benefit, and PFS compared to the other HRD+ subgroups, requiring a more thorough follow-up.

Only one-third of patients with advanced MSS/pMMR endometrial cancer exhibit a lasting response to the combination treatment of Pembrolizumab and Lenvatinib. The combined administration of these two drugs is based on Lenvatinib’s ability to modulate the tumor microenvironment, enabling Pembrolizumab to exert its effect. These findings underscore the importance of exploring tumor microenvironment parameters to identify markers that can accurately select candidates for this type of therapy. An open non-randomized observational association study was conducted at six clinical centers, involving a total of 28 patients with advanced MSS/pMMR endometrial cancer who received Pembrolizumab and Lenvatinib therapy. Using TSA-associated multiplex immunofluorescence, we analyzed the proportion of CD8+ T lymphocytes, CD20+ B lymphocytes, FoxP3+ T regulatory lymphocytes, and CD163+ macrophages in tumor samples prior to immunotargeted therapy. The percentage of CD20+ B lymphocytes and the CD8-to-CD20 lymphocytes ratio was significantly higher in patients who responded to treatment compared to non-responders (responders vs. non-responders: 0.24 (0.1–1.24)% vs. 0.08 (0.00–0.15)%, p = 0.0114; 1.44 (0.58–2.70) arb. unit vs. 19.00 (3.80–34.78) arb. unit, p = 0.0031). The sensitivity and specificity of these biomarkers were 85.71% and 70.59%, and 85.71% and 85.71%, respectively. The proportion of CD20+ B lymphocytes and the CD8-to-CD20 lymphocytes ratio in the stroma of endometrial cancer serves as both a prognostic marker of response to immunotargeted therapy and a prognostic factor for progression-free survival in patients.

Introduction. The combination of pembrolizumab and lenvatinib is the preferred second-line treatment for patients with recurrent endometrial cancer (EC) with proficient mismatch repair (pMMR) after platinum-based chemotherapy (CT). However, in real-world clinical practice, this option may be unavailable for some patients. Objective. To evaluate the efficacy of pembrolizumab plus lenvatinib compared with alternative СT regimens in patients with recurrent EC with pMMR tumor status upon progression after platinum based CT. Materials and Methods. A multicenter retrospective cohort study was conducted, including treatment data from patients with advanced and recurrent EC with рMMR tumor status from 37 oncology centers in Russia between December 2020 and December 2025. Patients were assigned to two groups according to the therapy received: immuno-targeted therapy (ITT) consisting of pembrolizumab plus lenvatinib, and alternative CT regimens, which included either platinum-based CT reinduction or non-platinum-based CT. To minimize the impact of baseline characteristic differences between the groups, patients were matched using cardinality matching (matching with maximization of the balanced sample size) at a 1:1 ratio. Group balancing was performed for the following variables: age, histological subtype, stage IV disease, receipt of radical/palliative surgery as first-line treatment, and platinum-free interval (PFI). The standardized mean difference was within ≤0.1 in absolute value for all variables. The primary endpoint was progression-free survival (PFS). Results. A total of 173 patients were enrolled in the study, of whom 106 constituted the ITT group and 67 constituted the CT group. From the initial study population, after cardinality matching, two groups of 67 patients each were formed. The median age was 60 (range, 36–80) years in the ITT group and 61 (range, 37–79) years in the alternative CT group; primary surgery was performed in 61/67 (91%) and 62/67 (93%) of patients, respectively. The median PFI was 6.9 (range, 0.0–106.5) months in the pembrolizumab–lenvatinib combination group and 9.1 (range, 0.0–69.0) months in the control group. At a median follow-up of 36.1 months (95% CI, 31.8–42.6), the median PFS in the ITT group was 9.9 months (95% CI, 7.2–12.9) versus 6.8 months (95% CI, 4.7–8.3) in the alternative CT group, which was statistically significant (HR 0.58; 95% CI, 0.40–0.85; p = 0.005). Conclusions. Treatment with the combination of pembrolizumab and lenvatinib is associated with longer PFS compared with alternative CT regimens in the matched cohort of patients with recurrent and advanced EC with MSS/pMMR tumor status upon progression after platinum-based CT.