Abstract P1-03-09: Highly reproducible decentralized gene expression analysis of ESR1, PGR, ERBB2 and MKi67 on an automated, standardized molecular diagnostics platform, GeneXpert

Background: Accurate assessment of ER, PgR, HER2, and Ki67 status using FFPE samples from patients with breast cancer is critical for appropriate patient management, yet immunohistochemistry (IHC), the most common method of assessing these markers, suffers from inherent variability due to pre-analytical/analytical factors and subjective interpretation by pathologists. Here we describe the GeneXpert (GX) Breast Cancer Stratifier RUO Assay (BC Strat), a real time quantitative PCR assay (RT-qPCR) kit which exhibits robust, highly reproducible mRNA measures of ESR1, PGR, ERBB2 (HER2) and MKi67.

The aims of this study were: 1) To assess the impact of variability contributed by pathologist-to-pathologist differences in the selection of the tumor area to be assayed, inter-laboratory assay performance, and macrodissection (MAC) vs. no macrodissection (nonMAC) on decentralized BC Strat results; and 2) to assess preliminary concordance of BC Strat with central IHC and FISH results.

Materials & Methods: The GX BC Strat is a cartridge-based RT-qPCR assay performed on the GeneXpert® Instrument (Cepheid) that automates RNA purification, RT-qPCR amplification and detection of mRNA of target genes (ESR1, PGR, ERBB2, and MKi67) and a control gene (CYFIP1) after sample preparation. Results are reported as delta cycle threshold (dCt) measurements (CYFIP1 Ct - target gene Ct) in less than 2 hrs.

Thirty-two invasive ductal carcinoma FFPE blocks were sourced based on varying levels of ER, PgR, HER2, and Ki67 expression and % tumor cell content/tumor area. Adjacent sections from each block were prepared as slides and sent to 3 external GX testing sites and a reference lab. Each site used its own pathologists/technicians to determine the % tumor cell content/tumor area, perform MAC or nonMAC, prepare lysates, and perform GX testing. Reference IHC/FISH was performed by Geneuity/MPLN (Maryville, TN, USA). Site-to-site concordance in GX results for MAC or nonMAC samples using pre-defined assay cutoffs per marker were analyzed, as were % tumor cell content/tumor area assessments between pathologists.

Results: BC Strat testing of 32 FFPE breast cancer samples with MAC demonstrated excellent GX site-to-site concordance in positive/negative status calls for ESR1 (100%), PGR (100%), ERBB2 (97%), and MKi67 (97%). In most cases, MAC vs. nonMAC had minimal impact on final positive/negative calls for GX, resulting in high overall concordance for MAC vs. nonMAC for ESR1 (91%), PGR (99%), ERBB2 (99%), and MKi67 (95%). The assay also demonstrated a strong overall concordance with IHC for ESR1 (97%), PGR (81%), ERBB2 (98%, IHC/FISH), and MKi67 (89%).

Conclusion: Decentralized performance of the GX BC Strat Assay is feasible and minimally affected by differences in tumor area selection and MAC techniques across tumors with a range of sizes, invasive tumor cell contents, and expression levels of ER, PgR, HER2, and Ki67. GX BC Strat dCt results across sites are highly reproducible and show good concordance of results with central lab IHC and HER2 FISH results. These results suggest standardized, decentralized testing of ESR1, PGR, ERBB2 and MKi67 by the GX BC Strat in local pathology labs is feasible.

Citation Format: Wong W, Ho KE, Wu N, Chu VC, Lalli P, Longshore JW, Klein J, Stonecypher M, Lykke C, Sherwood T, Davenport S, Weidler J, Bates M, Press MF. Highly reproducible decentralized gene expression analysis of ESR1, PGR, ERBB2 and MKi67 on an automated, standardized molecular diagnostics platform, GeneXpert [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-03-09.

The analysis of benefit and risk of combined pancreatic and renal transplantation versus renal transplantation alone

Currently, diabetes mellitus is the most common cause of renal failure in adults. However, combined pancreatic and renal transplantation (PRT) remains controversial when compared with renal transplantation alone (RTA) in diabetic recipients. We analyzed the results and morbidity in four age-matched groups--31 patients with Type I diabetes undergoing PRT before dialysis, 30 patients with diabetes who are dependent of dialysis undergoing PRT, 31 concurrent and historic patients with Type I diabetes undergoing RTA and 31 concurrent patients without diabetes undergoing RTA. All patients received cadaver donor organs and were managed with cyclosporine and prednisone immunosuppression with selective OKT3 induction. The four groups were comparable with respect to age, weight, gender, duration and severity of diabetes, dialysis type, number of retransplants, degree of sensitization, preservation time and matching. The groups differed with regard to duration of dialysis and period of follow-up evaluation, pretransplant blood transfusions, racial distribution and OKT3 induction therapy. PRT was associated with a greater morbidity rate as evidenced by a slightly higher incidence of rejection, infections and reoperations. The number of readmissions and hospitalization period during the first 12 months was also greater after PRT versus RTA. However, none of these differences were significant. No detrimental effect was noted on renal allograft function at one year; patient and graft survival was actually higher in the PRT groups. Quality of life was improved in nearly 90 percent of PRT recipients. Although the improved results after PRT may be attributed to selection bias, only lesser differences were noted among the four study groups. The aforementioned data suggest that appropriate patient selection can overcome the morbidity associated with PRT, resulting in excellent patient and graft survival with the potential for complete rehabilitation.

Plasma lipid changes in young adult couples consuming polyunsaturated meats and dairy products

Twenty-five young couples consumed either a saturated or polyunsaturated fat diet for a 20-week period. The polyunsaturated beef, lamb and dairy products, high in linoleic acid, were produced by feeding ruminant animals "protected lipid" feeds which prevent hydrogenation of fats in the rumen. The experimental design provided for four dietary groups: A) saturated diet for 20 weeks; B) polyunsaturated diet for 20 weeks; C) saturated diet for 10 weeks then polyunsaturated diet for 10 weeks; and D) polyunsaturated for 10 weeks then saturated diet for 10 weeks. Polyunsaturated-to-saturated ratios (linoleic: total saturated fatty acids) for the diets were: prestudy, 0.43-0.56; saturated 0.11-0.14; polyunsaturated, 0.56-0.62. Factors other than diet that appeared to affect cholesterol responses were carefully considered. During the initial 3 weeks (regimentation period) plasma cholesterol concentration decreased in all groups irrespective of diet. This was followed by two experimental periods in which the effects of the prescribed diets were readily apparent (response periods I and II). The final 4 weeks of the study were characterized by diminishing compliance with the dietary discipline (abatement period). Subjects in each group (A,B,C,D) were subdivided into high and low on a basis of each group's initial median cholesterol level. Those in the high subgroups were very responsive to dietary changes whereas those in the low subgroups were not. Combined responses of high subjects were: polyunsaturated diet, -10.7 mg/dl (P less than 0.025), saturated diet, d8 mg/dl (P less than 0.05). Combined difference between saturated and polyunsaturated diets was 18.5 mg/dl or approximately a 10% cholesterol difference between the experimental polyunsaturated and saturated diets.