Evaluation of a Novel Cystoscopic Compatible Cryocatheter for the Treatment of Bladder Cancer

Evaluation of a New Cystoscopic Cryocatheter and Method for the In Situ Destruction of Bladder Cancer: Preliminary In Vivo Study

Purpose: To assess the ability to deliver full-thickness bladder wall cryoablation through a cystoscopic approach using a new closed-loop 6F cryocatheter and thermal dose-controlled protocol. Materials and Methods: Evaluations were conducted using a chronic porcine model wherein 10 lesions/animal were created throughout the bladder (bladder wall, trigone region, ureteral orifice, and distal ureter). A 6F cryocatheter was passed through the working channel of a flexible cystoscope. Single 1- and 1.5-minute freeze protocols in a saline environment were evaluated and resultant lesion size was determined. A laparoscopic approach was utilized to observe the transmural extension of the ice propagation. Results: Studies demonstrated the generation of transmural lesions characterized by full-thickness histologic necrosis after freezing for 1.5 minutes regardless of tissue thickness (range 2-12 mm). All animals were found to have good overall health (maintained weight, appetite, mobility, and energy levels) throughout the recovery period. No significant deviations were noted in complete blood count and serum chemistry bloodwork except for elevated creatine kinase levels. Importantly, no fistulas or perforations were noted. Conclusions: The cryocatheter was able to rapidly and effectively freeze the bladder wall through a cystoscopic approach. The results showed the ability to consistently ablate an ∼1 cm diameter and up to 1.2 cm deep using a single 1.5-minute freeze protocol. Analysis of the ablation efficacy revealed ∼80% destruction within the frozen mass. Although further testing and refinement are needed, these studies demonstrate the potential of this new approach to provide a next-generation strategy for the treatment of bladder cancer.

An In Vitro Investigation into Cryoablation and Adjunctive Cryoablation/Chemotherapy Combination Therapy for the Treatment of Pancreatic Cancer Using the PANC-1 Cell Line

As the incidence of pancreatic ductal adenocarcinoma (PDAC) continues to grow, so does the need for new strategies for treatment. One such area being evaluated is cryoablation. While promising, studies remain limited and questions surrounding basic dosing (minimal lethal temperature) coupled with technological issues associated with accessing PDAC tumors and tumor proximity to vasculature and bile ducts, among others, have limited the use of cryoablation. Additionally, as chemotherapy remains the first-line of attack for PDAC, there is limited information on the impact of combining freezing with chemotherapy. As such, this study investigated the in vitro response of a PDAC cell line to freezing, chemotherapy, and the combination of chemotherapy pre-treatment and freezing. PANC-1 cells and PANC-1 tumor models were exposed to cryoablation (freezing insult) and compared to non-frozen controls. Additionally, PANC-1 cells were exposed to varying sub-clinical doses of gemcitabine or oxaliplatin alone and in combination with freezing. The results show that freezing to −10 °C did not affect viability, whereas −15 °C and −20 °C resulted in a reduction in 1 day post-freeze viability to 85% and 20%, respectively, though both recovered to controls by day 7. A complete cell loss was found following a single freeze below −25 °C. The combination of 100 nM gemcitabine (1.1 mg/m2) pre-treatment and a single freeze at −15 °C resulted in near-complete cell death (<5% survival) over the 7-day assessment interval. The combination of 8.8 µM oxaliplatin (130 mg/m2) pre-treatment and a single −15 °C freeze resulted in a similar trend of increased PANC-1 cell death. In summary, these in vitro results suggest that freezing alone to temperatures in the range of −25 °C results in a high degree of PDAC destruction. Further, the data support a potential combinatorial chemo/cryo-therapeutic strategy for the treatment of PDAC. These results suggest that a reduction in chemotherapeutic dose may be possible when offered in combination with freezing for the treatment of PDAC.