E.N. Prendergast

Three versus six cycles of adjuvant platinum-based chemotherapy in early stage clear cell ovarian carcinoma – A multi-institutional cohort

OBJECTIVES To determine if 6 versus 3cycles of adjuvant platinum-based chemotherapy with or without taxane impacts survival in early stage ovarian clear cell carcinoma (OCCC). METHODS We retrospectively identified all cases of stage I and II OCCC treated at 5 institutions from January 1994 through December 2011. Patients were divided into 2 groups: those who received 3 versus 6cycles of adjuvant chemotherapy. Our cohort consisted of 210 patients with stage IA-II disease, 116 of whom underwent full surgical staging. Cox proportional hazards regression and Kaplan-Meier analyses were performed to evaluate progression-free (PFS) and overall survival (OS) between groups. RESULTS Among 210 eligible patients, the median age was 53years (range 30-88). The majority of patients were Caucasian (83.8%). All patients received adjuvant chemotherapy with 90% receiving carboplatin and paclitaxel. Thirty-eight (18.1%) patients received 3cycles, and 172 (81.9%) patients received 6cycles of adjuvant treatment. Recurrence rate was comparable between groups (18.4% vs. 27.3% for 3 vs. 6cycles, p=0.4). There was no impact of 3 versus 6cycles of chemotherapy on PFS (hazard ratio [HR] 1.4; 95% confidence interval [CI] 0.63-3.12, p=0.4) or OS (HR 1.65; 95% CI 0.59-4.65, p=0.3) on univariate analysis. There was no benefit to more chemotherapy in stratified analysis by stage nor on multivariate analysis adjusting for the impact of stage. Subgroup analysis of surgically staged patients also showed no difference in survival between 3 versus 6cycles of chemotherapy. CONCLUSIONS Three cycles of platinum with or without taxane adjuvant chemotherapy were comparable to 6cycles with respect to recurrence and survival in patients diagnosed with early stage ovarian clear cell carcinoma in this retrospective multi-institutional cohort. CONDENSATION Three cycles of platinum with or without taxane adjuvant chemotherapy are comparable to 6 cycles with respect to recurrence and survival in patients diagnosed with early stage ovarian clear cell carcinoma in this retrospective multi-institutional cohort.

Optimizing exosomal RNA isolation for RNA-Seq analyses of archival sera specimens

Exosomes are endosome-derived membrane vesicles that contain proteins, lipids, and nucleic acids. The exosomal transcriptome mediates intercellular communication, and represents an understudied reservoir of novel biomarkers for human diseases. Next-generation sequencing enables complex quantitative characterization of exosomal RNAs from diverse sources. However, detailed protocols describing exosome purification for preparation of exosomal RNA-sequence (RNA-Seq) libraries are lacking. Here we compared methods for isolation of exosomes and extraction of exosomal RNA from human cell-free serum, as well as strategies for attaining equal representation of samples within pooled RNA-Seq libraries. We compared commercial precipitation with ultracentrifugation for exosome purification and confirmed the presence of exosomes via both transmission electron microscopy and immunoblotting. Exosomal RNA extraction was compared using four different RNA purification methods. We determined the minimal starting volume of serum required for exosome preparation and showed that high quality exosomal RNA can be isolated from sera stored for over a decade. Finally, RNA-Seq libraries were successfully prepared with exosomal RNAs extracted from human cell-free serum, cataloguing both coding and non-coding exosomal transcripts. This method provides researchers with strategic options to prepare RNA-Seq libraries and compare RNA-Seq data quantitatively from minimal volumes of fresh and archival human cell-free serum for disease biomarker discovery.