Abstract B083: Disease marker-specific disseminated tumor cells in bone are rare at the time of radical prostatectomy

Introduction: In prostate cancer (PCa), DTCs are cells that have escaped the primary lesion and enter the metastatic site, most commonly the bone marrow (BM). The pelvis is a common metastatic site for prostate cancer metastases. However, it is unclear when PCa cells leave the prostate and travel to bone in clinically localized disease. Thus, we studied whether PCa DTCs can be detected at the time of radical prostatectomy (RP) by performing a bone marrow aspiration (BMA) from the anterior iliac crest (AIC) at the time of surgery. Methods: The study protocol was approved by the institutional review board at the Johns Hopkins Medical Institutions. Informed consent to perform BMA was obtained from 94 clinically localized PCa patients undergoing a robotic-assisted laparoscopic prostatectomy (RALP). In the supine position, patients underwent general anesthesia and were prepped and draped in a normal sterile fashion. Aspiration was performed by the attending surgeon prior to first incision and obtained percutaneously from the AIC using a BM biopsy needle (11G x 100 mm Hospital Trapsystem, HS Hospital Service S.p.A.). 8-20 mL of BM were aspirated into 1 or 2 10-mL syringes (BD) and transferred into collection tubes through an 18-gauge needle (PrecisionGlide, BD). Samples were distributed among 7 different principal investigators within 24 hours of collection for DTC analyses. One type of analysis included the AdnaTest, which first involved collecting 8 mL of BM from 43/77 (56%) patients. 5 mL of whole cell extract was then assayed with the AdnaTest ProstateCancerSelect kit (Qiagen) to enrich for epithelial-marker, EpCAM, positive cells using immunomagnetic beads. Reverse transcription (SensiScript RT kit, Qiagen) and real-time qPCR quantified the expression of RPL13A (control, ribosomal protein), EPCAM (epithelial), NKX3.1, prostate-specific antigen (PSA), androgen receptor full length (AR), and HOXB13 (prostate-specific). DTC detection was defined as positive prostate-specific marker expression in the BM. Quality control was performed with Sanger sequencing. Results: BM was successfully obtained from 77/94 (82%) patients. The median (range) age was 62 (43-76) years and the median (range) preoperative PSA was 6 (1.3-62.6) ng/mL. 8/77 (10%) patients had RP Gleason Score 6 disease, 37/77 (48%) were Gleason 3+4, 18/77 (23%) were 4+3, and 13/77 (17%) were Gleason 8-10. One patient had an undetermined RP Gleason due to effects from neoadjuvant chemotherapy. 65/77 (85%) had PSA 20. 50/77 (65%) had pT2, 21/77 (27%) had pT3a, and 6/77 (8%) had pT3b diseases. 3/77 (4%) had lymph node metastasis as confirmed in their pathology. The average time to collect BM and transfer into tubes was 2.5 minutes. The median volume collected was 10.5 mL. RALP was performed without BMA-associated complication and there were no reports of BMA-induced postoperative complications including discomfort at the BMA site. Patients were discharged on postoperative day one. For the AdnaTest, 1/43 (2%) BM expressed PSA and 43/43 (100%) expressed EpCAM. Conclusions: We demonstrated an efficient percutaneous approach to BMA from the AIC with 77/94 (82%) successful attempts to obtain BMA and an average collection time of 2.5 minutes. This technique is feasible and safe with no BMA-associated surgical complications or patient discomfort postoperatively. Samples are utilized to study PCa dissemination to bone. Putative PSA positive DTCs can be identified at the time of RP. Citation Format: Emily A. Caruso, Stephanie Glavaris, Heather J. Chalfin, Kenneth C. Valkenburg, Mohamad E. Allaf, Misop Han, Kenneth Pienta. Disease marker-specific disseminated tumor cells in bone are rare at the time of radical prostatectomy [abstract]. In: Proceedings of the AACR Special Conference: Prostate Cancer: Advances in Basic, Translational, and Clinical Research; 2017 Dec 2-5; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(16 Suppl):Abstract nr B083.