Plasma tumor gene conversions after one cycle abiraterone acetate for metastatic castration-resistant prostate cancer: a biomarker analysis of a multicenter international trial.
Plasma tumor DNA fraction is prognostic in metastatic cancers. This could improve risk stratification before commencing a new treatment. We hypothesized that a second sample collected after one cycle of treatment could refine outcome prediction of patients identified as poor prognosis based on plasma DNA collected pre-treatment.
Plasma DNA [128 pre-treatment, 134 cycle 2 day 1 (C2D1), and 49 progression] from 151 chemotherapy-naive metastatic castration-resistant prostate cancer (mCRPC) patients in a phase II study of abiraterone acetate (NCT01867710) were subjected to custom targeted next-generation sequencing covering exons of these genes: TP53, AR, RB1, PTEN, PIK3CA, BRCA1, BRCA2, ATM, CDK12, CHEK2, FANCA HDAC2 and PALB2. We also captured 1500 pan-genome regions enriched for single nucleotide polymorphisms to allow detection of tumor DNA using the rolling B-allele method. We tested associations with overall survival (OS) and progression-free survival (PFS).
Plasma tumor DNA detection was associated with shorter OS [hazard ratio (HR): 2.89, 95% confidence intervals (CI): 1.77-4.73, P ≤ 0.0001] and PFS (HR: 2.05; 95% CI: 1.36-3.11, P < 0.001). Using a multivariable model including plasma tumor DNA, patients who had a TP53, RB1 or PTEN gene alteration pre-treatment and at C2D1 had a significantly shorter OS than patients with no alteration at either time point (TP53: HR 7.13, 95% CI 2.37-21.47, P < 0.001; RB1: HR 6.24, 95% CI 1.97-19.73, P = 0.002; PTEN: HR 11.9, 95% CI 3.6-39.34, P < 0.001). Patients who were positive pre-treatment and converted to undetectable had no evidence of a difference in survival compared with those who were undetectable pre-treatment (P = 0.48, P = 0.43, P = 0.5, respectively). Progression samples harbored AR gain in all patients who had gain pre-treatment (9/49) and de novo AR somatic point mutations were detected in 8/49 patients.
Plasma gene testing after one cycle treatment refines prognostication and could provide an early indication of treatment benefit.
Publication Date: 2021-04-02
Journal: Annals of oncology : official journal of the European Society for Medical Oncology
Correlation of genetic alterations by whole-exome sequencing with clinical outcomes of glioblastoma patients from the Lebanese population.
Glioblastoma (GBM) is an aggressive brain tumor associated with high degree of resistance to treatment. Given its heterogeneity, it is important to understand the molecular landscape of this tumor for the development of more effective therapies. Because of the different genetic profiles of patients with GBM, we sought to identify genetic variants in Lebanese patients with GBM (LEB-GBM) and compare our findings to those in the Cancer Genome Atlas (TCGA).
We performed whole exome sequencing (WES) to identify somatic variants in a cohort of 60 patient-derived GBM samples. We focused our analysis on 50 commonly mutated GBM candidate genes and compared mutation signatures between our population and publicly available GBM data from TCGA. We also cross-tabulated biological covariates to assess for associations with overall survival, time to recurrence and follow-up duration.
We included 60 patient-derived GBM samples from 37 males and 23 females, with age ranging from 3 to 80 years (mean and median age at diagnosis were 51 and 56, respectively). Recurrent tumor formation was present in 94.8% of patients (n = 55/58). After filtering, we identified 360 somatic variants from 60 GBM patient samples. After filtering, we identified 360 somatic variants from 60 GBM patient samples. Most frequently mutated genes in our samples included ATRX, PCDHX11, PTEN, TP53, NF1, EGFR, PIK3CA, and SCN9A. Mutations in NLRP5 were associated with decreased overall survival among the Lebanese GBM cohort (p = 0.002). Mutations in NLRP5 were associated with decreased overall survival among the Lebanese GBM cohort (p = 0.002). EGFR and NF1 mutations were associated with the frontal lobe and temporal lobe in our LEB-GBM cohort, respectively.
Our WES analysis confirmed the similarity in mutation signature of the LEB-GBM population with TCGA cohorts. It showed that 1 out of the 50 commonly GBM candidate gene mutations is associated with decreased overall survival among the Lebanese cohort. This study also highlights the need for studies with larger sample sizes to inform clinicians for better prognostication and management of Lebanese patients with GBM.
Publication Date: 2020-11-26
Journal: PloS one