bims-tumhet Biomed News
on Tumor Heterogeneity
Issue of 2021‒08‒01
nine papers selected by
Sergio Marchini
Humanitas Research

  1. Exp Cell Res. 2021 Jul 22. pii: S0014-4827(21)00295-0. [Epub ahead of print]406(1): 112742
      BACKGROUND: Mutations at sites crucial for the interaction between RAD51 and BRC domains impair the ability of BRCA2 homologous recombination. We aimed to clarify whether BRCA2 BRC domain-associated mutation correlates with sensibility of platinum-based chemotherapy and survival in high-grade serous ovarian cancer (HGSOC).METHODS: We identified BRCA2 BRC domain mutations by sequencing PCR-amplified amplicons of genomic DNA isolated from tumor tissues and peripheral blood leukocytes (PBL)in 113 patients with advanced EOC, and assessed platinum-free interval (PFI), progression-free survival (PFS) and overall survival (OS).
    RESULTS: 21.23% (24 of 113) cases with somatic missense mutation but not germline mutation were identified. Among 24 cases with mutation, 33.3% (8 of 24) cases with nonsense mutation (C-terminal truncation) significantly prolonged median PFI (37 vs 8 months,P = 0.000), PFS (43 vs 14 months, p = 0.000) and OS (56 vs 31 months, P = 0.002); 66.7% (16 of 24) cases with missense mutation also prolonged median PFI (15 vs 8 months, P = 0.044), PFS (21 vs 14 months, P = 0.049) and OS (38 vs 31 months, P = 0.037), compared to those without any mutation.
    CONCLUSIONS: Somatic mutations in BRCA2 BRC domain confer a higher sensitivity to platinum-based therapy and are associated with a favourable survival in HGSOC.
    Keywords:  BRCA2; Epithelial ovarian cancer; Homologous recombination; Platinum sensitivity; RAD51; Survival
  2. Cochrane Database Syst Rev. 2021 Jul 30. 7 CD005343
      BACKGROUND: Epithelial ovarian cancer presents at an advanced stage in the majority of women. These women require a combination of surgery and chemotherapy for optimal treatment. Conventional treatment has been to perform surgery first and then give chemotherapy. However, there may be advantages to using chemotherapy before surgery.OBJECTIVES: To assess whether there is an advantage to treating women with advanced epithelial ovarian cancer with chemotherapy before debulking surgery (neoadjuvant chemotherapy (NACT)) compared with conventional treatment where chemotherapy follows debulking surgery (primary debulking surgery (PDS)).
    SEARCH METHODS: We searched the following databases up to 9 October 2020: the Cochrane Central Register of Controlled Trials (CENTRAL), Embase via Ovid, MEDLINE (Silver Platter/Ovid), PDQ and MetaRegister. We also checked the reference lists of relevant papers that were identified to search for further studies. The main investigators of relevant trials were contacted for further information.
    SELECTION CRITERIA: Randomised controlled trials (RCTs) of women with advanced epithelial ovarian cancer (Federation of International Gynaecologists and Obstetricians (FIGO) stage III/IV) who were randomly allocated to treatment groups that compared platinum-based chemotherapy before cytoreductive surgery with platinum-based chemotherapy following cytoreductive surgery.
    DATA COLLECTION AND ANALYSIS: Two review authors independently extracted data and assessed risk of bias in each included trial. We extracted data of overall (OS) and progression-free survival (PFS), adverse events, surgically-related mortality and morbidity and quality of life outcomes.  We used GRADE methods to determine the certainty of evidence.
    MAIN RESULTS: We identified 2227 titles and abstracts through our searches, of which five RCTs of varying quality and size met the inclusion criteria. These studies assessed a total of 1774 women with stage IIIc/IV ovarian cancer randomised to NACT followed by interval debulking surgery (IDS) or PDS followed by chemotherapy. We pooled results of the four studies where data were available and found little or no difference with regard to overall survival (OS) (Hazard Ratio (HR) 0.96, 95% CI 0.86 to 1.08; participants = 1692; studies = 4; high-certainty evidence) or progression-free survival in four trials where we were able to pool data (Hazard Ratio 0.98, 95% CI 0.88 to 1.08; participants = 1692; studies = 4; moderate-certainty evidence). Adverse events, surgical morbidity and quality of life (QoL) outcomes were variably and incompletely reported across studies. There are probably clinically meaningful differences in favour of NACT compared to PDS with regard to overall postoperative serious adverse effects (SAE grade 3+): 6% in NACT group, versus 29% in PDS group, (risk ratio (RR) 0.22, 95% CI 0.13 to 0.38; participants = 435; studies = 2; heterogeneity index (I2) = 0%; moderate-certainty evidence). NACT probably results in a large reduction in the need for stoma formation: 5.9% in NACT group, versus 20.4% in PDS group, (RR 0.29, 95% CI 0.12 to 0.74; participants = 632; studies = 2; I2 = 70%; moderate-certainty evidence), and probably reduces the risk of needing bowel resection at the time of surgery: 13.0% in NACT group versus 26.6% in PDS group (RR 0.49, 95% CI 0.30 to 0.79; participants = 1565; studies = 4; I2 = 79%; moderate-certainty evidence). NACT reduces postoperative mortality: 0.6% in NACT group, versus 3.6% in PDS group, (RR 0.16, 95% CI 0.06 to 0.46; participants = 1623; studies = 5; I2 = 0%; high-certainty evidence). QoL on the European Organization for the Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30) scale produced inconsistent and imprecise results in three studies (MD -0.29, 95% CI -2.77 to 2.20; participants = 524; studies = 3; I2 = 81%; very low-certainty evidence) but the evidence is very uncertain and should be interpreted with caution.
    AUTHORS' CONCLUSIONS: The available high to moderate-certainty evidence suggests there is little or no difference in primary survival outcomes between PDS and NACT. NACT probably reduces the risk of serious adverse events, especially those around the time of surgery, and reduces the risk of postoperative mortality and the need for stoma formation. These data will inform women and clinicians (involving specialist gynaecological multidisciplinary teams) and allow treatment to be tailored to the person, taking into account surgical resectability, age, histology, stage and performance status. Data from an unpublished study and ongoing studies are awaited.
  3. Trends Mol Med. 2021 Jul 23. pii: S1471-4914(21)00182-9. [Epub ahead of print]
    Keywords:  cancer; companion diagnostics; ctDNA relapse; early detection; liquid biopsy
  4. Cancer Res. 2021 Jul 28. pii: canres.0774.2021. [Epub ahead of print]
      In high-grade serous ovarian carcinoma (HGSC), deleterious mutations in DNA repair gene RAD51C are established drivers of defective homologous recombination and are emerging biomarkers of PARP inhibitor (PARPi) sensitivity. RAD51C promoter methylation (meRAD51C) is detected at similar frequencies to mutations, yet its effects on PARPi responses remain unresolved. In this study, three HGSC patient-derived xenograft (PDX) models with methylation at most or all examined CpG sites in the RAD51C promoter show responses to PARPi. Both complete and heterogeneous methylation patterns were associated with RAD51C gene silencing and homologous recombination deficiency (HRD). PDX models lost meRAD51C following treatment with PARPi rucaparib or niraparib, where a single unmethylated copy of RAD51C was sufficient to drive PARPi resistance. Genomic copy number profiling of one of the PDX models using SNP arrays revealed that this resistance was acquired independently in two genetically distinct lineages. In a cohort of 11 patients with RAD51C-methylated HGSC, various patterns of meRAD51C were associated with genomic 'scarring', indicative of HRD history, but exhibited no clear correlations with clinical outcome. Differences in methylation stability under treatment pressure were also observed between patients, where one HGSC was found to maintain meRAD51C after 6 lines of therapy (4 platinum-based), whilst another HGSC sample was found to have heterozygous meRAD51C and elevated RAD51C gene expression (relative to homozygous meRAD51C controls) after only neo-adjuvant chemotherapy. As meRAD51C loss in a single gene copy was sufficient to cause PARPi resistance in PDX, methylation zygosity should be carefully assessed in previously treated patients when considering PARPi therapy.
  5. PLoS One. 2021 ;16(7): e0255142
      Ovarian cancer (OC), the eighth-leading cause of cancer-related death among females worldwide, is mainly represented by epithelial OC (EOC) that can be further subdivided into four subtypes: serous (75%), endometrioid (10%), clear cell (10%), and mucinous (3%). Major reasons for high mortality are the poor biological understanding of the OC mechanisms and a lack of reliable markers defining each EOC subtype. MicroRNAs (miRNAs) are small non-coding RNA molecules that regulate gene expression primarily by targeting messenger RNA (mRNA) transcripts. Their aberrant expression patterns have been associated with cancer development, including OC. However, the role of miRNAs in tumorigenesis is still to be determined, mainly due to the lack of consensus regarding optimal methodologies for identification and validation of miRNAs and their targets. Several tools for computational target prediction exist, but false interpretations remain a problem. The experimental validation of every potential miRNA-mRNA pair is not feasible, as it is laborious and expensive. In this study, we analyzed the correlation between global miRNA and mRNA expression patterns derived from microarray profiling of 197 EOC patients to identify the signatures of miRNA-mRNA interactions associated with overall survival (OS). The aim was to investigate whether these miRNA-mRNA signatures might have a prognostic value for OS in different subtypes of EOC. The content of our cohort (162 serous carcinomas, 15 endometrioid carcinomas, 11 mucinous carcinomas, and 9 clear cell carcinomas) reflects a real-world scenario of EOC. Several interaction pairs between 6 miRNAs (hsa-miR-126-3p, hsa-miR-223-3p, hsa-miR-23a-5p, hsa-miR-27a-5p, hsa-miR-486-5p, and hsa-miR-506-3p) and 8 mRNAs (ATF3, CH25H, EMP1, HBB, HBEGF, NAMPT, POSTN, and PROCR) were identified and the findings appear to be well supported by the literature. This indicates that our study has a potential to reveal miRNA-mRNA signatures relevant for EOC. Thus, the evaluation on independent cohorts will further evaluate the performance of such findings.
  6. ESMO Open. 2021 Jul 27. pii: S2059-7029(21)00173-3. [Epub ahead of print]6(4): 100212
      BACKGROUND: There is limited evidence for the benefit of olaparib in platinum-resistant ovarian cancer (PROC) patients with BRCA wild-type tumors. This study investigated whether this combination of a DNA-damaging chemotherapy plus olaparib is effective in PROC regardless BRCA status.PATIENTS AND METHODS: Patients with high-grade serous or endometrioid ovarian carcinoma and one previous PROC recurrence were enrolled regardless of BRCA status. Patients with ≤4 previous lines (up to 5 in BRCA-mut) with at least one previous platinum-sensitive relapse were included; primary PROC was allowed only in case of BRCA-mut. Patients initially received six cycles of olaparib 300 mg b.i.d. (biduum) + intravenous pegylated liposomal doxorubicin (PLD) 40 mg/m2 (PLD40) every 28 days, followed by maintenance with olaparib 300 mg b.i.d. until progression or toxicity. The PLD dose was reduced to 30 mg/m2 (PLD30) due to toxicity. The primary endpoint was progression-free survival (PFS) at 6 months (6m-PFS) by RECIST version 1.1. A proportion of 40% 6m-PFS or more was considered of clinical interest.
    RESULTS: From 2017 to 2020, 31 PROC patients were included. BRCA mutations were present in 16%. The median of previous lines was 2 (range 1-5). The overall disease control rate was 77% (partial response rate of 29% and stable disease rate of 48%). After a median follow-up of 10 months, the 6m-PFS and median PFS were 47% and 5.8 months, respectively. Grade ≥3 treatment-related adverse events occurred in 74% of patients, with neutropenia/anemia being the most frequent. With PLD30 serious AEs were less frequent than with PLD40 (21% versus 47%, respectively); moreover, PLD30 was associated with less PLD delays (32% versus 38%) and reductions (16% versus 22%).
    CONCLUSIONS: The PLD-olaparib combination has shown significant activity in PROC regardless of BRCA status. PLD at 30 mg/m2 is better tolerated in the combination.
    Keywords:  BRCA wild-type; PARP inhibitor; olaparib; pegylated liposomal doxorubicin; platinum-resistant recurrent ovarian cancer
  7. NAR Cancer. 2021 Sep;3(3): zcab028
      Acquired PARP inhibitor (PARPi) resistance in BRCA1- or BRCA2-mutant ovarian cancer often results from secondary mutations that restore expression of functional protein. RAD51C is a less commonly studied ovarian cancer susceptibility gene whose promoter is sometimes methylated, leading to homologous recombination (HR) deficiency and PARPi sensitivity. For this study, the PARPi-sensitive patient-derived ovarian cancer xenograft PH039, which lacks HR gene mutations but harbors RAD51C promoter methylation, was selected for PARPi resistance by cyclical niraparib treatment in vivo. PH039 acquired PARPi resistance by the third treatment cycle and grew through subsequent treatment with either niraparib or rucaparib. Transcriptional profiling throughout the course of resistance development showed widespread pathway level changes along with a marked increase in RAD51C mRNA, which reflected loss of RAD51C promoter methylation. Analysis of ovarian cancer samples from the ARIEL2 Part 1 clinical trial of rucaparib monotherapy likewise indicated an association between loss of RAD51C methylation prior to on-study biopsy and limited response. Interestingly, the PARPi resistant PH039 model remained platinum sensitive. Collectively, these results not only indicate that PARPi treatment pressure can reverse RAD51C methylation and restore RAD51C expression, but also provide a model for studying the clinical observation that PARPi and platinum sensitivity are sometimes dissociated.
  8. Cancer Cell. 2021 Jul 16. pii: S1535-6108(21)00381-0. [Epub ahead of print]
      Single-cell technologies are emerging as powerful tools for cancer research. These technologies characterize the molecular state of each cell within a tumor, enabling new exploration of tumor heterogeneity, microenvironment cell-type composition, and cell state transitions that affect therapeutic response, particularly in the context of immunotherapy. Analyzing clinical samples has great promise for precision medicine but is technically challenging. Successfully identifying predictors of response requires well-coordinated, multi-disciplinary teams to ensure adequate sample processing for high-quality data generation and computational analysis for data interpretation. Here, we review current approaches to sample processing and computational analysis regarding their application to translational cancer immunotherapy research.
    Keywords:  computational biology; single-cell proteomics; single-cell transcriptomics; spatial proteomics; spatial transcriptomics; translational medicine; tumor immunology
  9. DNA Repair (Amst). 2021 Jul 17. pii: S1568-7864(21)00137-3. [Epub ahead of print]106 103181
      DNA double strand breaks (DSB) are cytotoxic lesions that can lead to genome rearrangements and genomic instability, which are hallmarks of cancer. The two main DSB repair pathways are non-homologous end joining and homologous recombination (HR). While HR is generally highly accurate, it has the potential for rearrangements that occur directly or through intermediates generated during the repair process. Whole genome sequencing of cancers has revealed numerous types of structural rearrangement signatures that are often indicative of repair mediated by sequence homology. However, it can be challenging to delineate repair mechanisms from sequence analysis of rearrangement end products from cancer genomes, or even model systems, because the same rearrangements can be generated by different pathways. Here, we review homology-directed repair pathways and their consequences. Exploring those pathways can lead to a greater understanding of rearrangements that occur in cancer cells.
    Keywords:  Break-induced replication; Chromosome rearrangement; Homologous recombination; Microhomology-mediated end joining; Single-strand annealing