3115 - Final Results of the First Clinical Trial of a Novel Unidirectional Permanent Device for Intraoperative Brachytherapy

I. Youssef¹, A. L. Damato², G. N. Cohen², P. B. Romesser¹, N. K. Taunk³, K. Episcopia², C. H. Crane¹, P. Paty⁴, J. Garcia-Aguilar⁵, M. Weiser⁴, J. J. Smith⁵, G. M. Nash⁵, E. Cha⁵, A. Taggar⁶, and A. J. Wu¹; ¹Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, ²Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, ³Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, PA, ⁴Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, NY, ⁵Memorial Sloan Kettering Cancer Center, New York, NY, ⁶Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, ON, Canada

Purpose/Objective(s): The CivaSheet® is a novel device consisting of unidirectionally shielded Pd-103 sources embedded in a polymer sheet. This facilitates intraoperative placement of permanent brachytherapy seeds in a surgical tumor bed, while minimizing radiation dose to structures overlying the bed. No clinical trial data is yet published for this device. We prospectively investigated its feasibility as an alternative to standard intraoperative radiation therapy (IORT) for pelvic tumors. Materials/

Methods: The CivaSheet® is a novel device consisting of unidirectionally shielded Pd-103 sources embedded in a polymer sheet. This facilitates intraoperative placement of permanent brachytherapy seeds in a surgical tumor bed, while minimizing radiation dose to structures overlying the bed. No clinical trial data is yet published for this device. We prospectively investigated its feasibility as an alternative to standard intraoperative radiation therapy (IORT) for pelvic tumors.
Results: Ten patients (pts) were enrolled and underwent surgery. Eight patients successfully underwent CivaSheet implantation, exceeding the primary feasibility endpoint. Eight pts had colorectal, one had appendiceal, and one had urothelial cancer. All but three pts received prior EBRT (45-50.4Gy). The two feasibility exclusions were technically unfavorable for CivaSheet based on intraoperative assessment of tumor bed configuration and underwent standard IORT. All CivaSheet pts were treated to the pelvic sidewall or presacral space. Median prescription dose was 100Gy (range 91.1-100Gy) to 5mm depth, and median area treated was 40cm2 (range 16-75cm2). Median follow-up from date of implant was 25 months. One pt had a marginal recurrence 3 months following implant, and 1 pt recurred at implant site after 13 months. ½-year OS was 75%/63%, and ½-year LC was 86%/69%. One pt died 2 weeks after surgery from cardiopulmonary arrest, unrelated to the device. No pts had device-related Grade 4-5 AEs. One pt developed temporary grade 3 bowel obstruction 18 months after with unclear relationship to CivaSheet, as well as wound dehiscence at a location separate from CivaSheet. No other grade 3+ AEs related to CivaSheet were observed. Post-implant stability was satisfactory in all pts, based on serial CT scans up to 12 months post-implantation.
Conclusion: This is the first clinical trial of CivaSheet and demonstrated that it is a feasible and promising technique for IORT in pelvic malignancies. Because of several unique and potentially advantageous characteristics compared to standard IORT, this supports further prospective study of CivaSheet as a means to prevent local recurrence in concert with surgical resection.