Yield Of Adequate Tissue On Research Biopsies With Pathologic Review

e17626 Background: Clinical trials are increasingly requiring tissue biopsies in order to further our understanding of tumor biology and mechanisms of drug sensitivity and resistance. Several studies confirm that obtaining tissue for research biopsies is equally as successful as that of diagnostic biopsies, however little is known about the adequacy of this tissue for evaluation. Methods: We reviewed the medical records for 37 patients (pts) enrolled in two phase I trials that mandated paired biopsies. Trial one (single agent veliparib) required collection of at least two core biopsies, while trial 2 (veliparib with carboplatin and paclitaxel) required a minimum of three cores all no less than 18 gauge diameter and 1 cm in length. At least one core was sent for pathologic review to assess for biopsy adequacy. On-site touch prep was also performed in the majority of cases and all pts were assessed by interventional radiology for biopsy feasibility as an eligibility requirement for study entry. Results: Initial biopsy was attempted in 36/37 pts and subsequent paired biopsy in 25/36, most ultrasound-guided by interventional radiology. Most common reason for aborted biopsy attempt on the subsequent biopsy was suspected poor yield, due to response to treatment. Of the 61 biopsies performed, 75% were deemed adequate for evaluation by pathology. Pre-treatment biopsy yield was 80.5% compared to 68% for that of subsequent biopsies. Low quantity/quality and paucity of tumor cells were the most commonly cited reasons for tissue insufficiency. Overall, only 15/37 pts (40%) achieved two adequate paired biopsies. The sites most biopsied were superficial lymph nodes (27%) and liver (23%). Sites of highest and lowest yield overall were the skin (85%) and omentum (62%) respectively. Conclusions: Despite having on site touch prep, interventional radiology review and real time pathologic tissue adequacy assessment, less than half of pts had adequate paired biopsies. We suspect the actual specimen adequacy in research biopsies may be sub-optimal overall and recommend real time pathologic review for adequacy. Additionally, these data suggest that trials may benefit from increasing study enrollment to ensure appropriate power in studies with mandatory research biopsies.