Nitrous Oxide For Endoscopic Ablation of Refractory Barrett's Esophagus (NO FEAR-BE)

Eligibility will be determined based on historical local pathology and medical record information. Informed consent will be obtained and eligible subjects will be treated with the Cryoballoon Focal Ablation System (CbFAS) at baseline. Subjects will return every 3 months +/- 6 weeks for repeat treatment for up to 12 months OR until complete eradication of intestinal metaplasia (CEIM) and complete eradication of dysplasia (CED) are achieved (at which point subjects enter the follow-up phase), whichever occurs first. Treatment procedures will be performed on an outpatient basis according to the site's standards of care for anesthesia and sedation during esophagogastroduodenoscopy (EGD) procedures. EGD examinations will be performed using high definition White Light Endoscopy (WLE), plus Narrow Band Imaging (NBI) or i-SCAN to assess BE measurements and identify tissue landmarks and ablation zones. A high definition endoscope will be used for all ablations performed with the CryoBalloon Focal Ablation System (CbFAS). The System will be used according to the instructions for use provided with the product and in accordance with the current standard of care for treatment of BE. Repeat cryoablation may be performed if esophageal columnar mucosa is visible on EGD or if intervening biopsies (if a site chooses to obtain intervening biopsies as standard of care) are positive for any esophageal columnar epithelium until complete eradication of all unwanted tissue is achieved. Intervening endoscopic mucosal resection (EMR) or endoscopic submucosal dissection (ESD) after enrollment may be performed for nodular areas detected after baseline. EMR/ESD may be performed at the same session as the cryoablation if the EMR/ESD site is \>=3cm away from the ablation target site. Cryoablation should be performed before EMR/ESD. If the EMR/ESD site is within 3cm of target treatment area, then CbFAS will be delayed for at least 6 weeks. Residual islands of columnar mucosa of \<5 mm in diameter each and \<= 3 total can be treated with Argon Plasma Coagulation (APC) and/or CbFAS at the discretion of the treating physician to avoid over treatment of neo-squamous mucosa. Stenosis requiring treatment based on the physician's discretion, which develops after enrollment, will be treated with standard of care balloon- or wire-guided dilation. Cryoablation may be performed at the same session if the dilated site is \>= 3 cm from the target cryoablation site. Otherwise, cryoablation will be postponed to another visit within 1 month +/- 2 weeks. When CbFAS treatment is received, subjects will be asked to complete assessments immediately after CbFAS treatment, and will be contacted 1 day, 7 days, and 30 days after the procedure. If no visible BE is present during the endoscopy, then at least eight (8) biopsies in total will be obtained: at least four (4) from the distal esophagus in the neosquamous epithelium and at least four (4 from the gastroesophageal junction (GEJ), top of gastric folds (TGF), or gastric cardia. Additional biopsies may be taken as per standard of care guidelines at the site. Biopsies will be read by local expert pathologist. If biopsies indicate CEIM and CED, then subjects will enter the 12 month follow-up phase. If biopsies do not indicate CEIM and CED, then subjects will return for additional CbFAS treatment in 3 months +/-6 weeks. Non-responders are defined as subjects who have not achieved CEIM and CED at 12 months post baseline CbFAS treatment. Non-responders at 12 months will exit the study and continue treatment at the physician's discretion and according to standard of care at each site. Subjects who achieve CEIM and CED within 12 months of the baseline CbFAS procedure will enter a 12 month follow-up phase. Subjects will be followed per routine care guidelines for their condition, described below: Subjects with baseline LGD will return at 6 and 12 months from the initial CEIM and CED date for follow-up (+/-4 weeks). Subjects with baseline HGD or IMC will return at 3, 6, 9, and 12 months from initial CEIM and CED date for follow-up (+/- 4 weeks). During follow-up procedures, high definition WLE, plus NBI or i-SCAN will be used to assess BE measurements, and then at least eight (8) biopsies in total will be obtained: at least four (4) from the distal esophagus in the neosquamous epithelium and at least four (4 from the gastroesophageal junction (GEJ), top of gastric folds (TGF), or gastric cardia. Additional biopsies may be taken as per standard of care guidelines at the site. Biopsies will be read by local expert pathologist. If recurrent BE is detected during follow-up endoscopy with biopsy demonstrating compatible histology, then subjects will be exited from the study and treated at the physician's discretion. Study participation is complete if: 1) Subject has not reached CEIM and CED at 12 month post baseline treatment; or 2) If BE or dysplasia recur after initial CEIM and CED post enrollment; 3) Subject is discovered to be ineligible after enrollment; or 4) After completion of the 12 month follow-up EGD with biopsies.