Dose-escalation pilot study investigating whole abdomen radiation therapy for feline chronic inflammatory enteropathy

We are studying whether a low-dose radiation treatment to the whole abdomen can safely and effectively help cats with chronic inflammatory enteropathy/bowel disease (CIE). The goals of the study are to find out if this treatment is well-tolerated and to determine the lowest dose that can reduce gut inflammation while keeping side effects to a minimum and, ideally, none. Ultimately, we hope this treatment could help manage CIE symptoms and may reduce or even eliminate the need for daily medications or strict diet for your cat.

Inclusion Criteria

• Biopsy confirmed CIE with lymphocytic and/or plasmacytic inflammation
• Prior diet trial (novel or hydolyzed protein) for > 2 weeks within 2 months
• Ongoing need for medical therapy beyond diet
• Completed GI evaluation (gastric and duodenol endoscopy with biopsies; ileal biopsies recommended)
• Acceptable clinical status (ECOG <2, adequate blood counts and organ function)
• Suitable for repeated anesthesia
• Owner consent

Exclusion Criteria

• Diagnosis of low-grade intestinal T-cell lymphoma (LGITL)
• Significant abnormalities that preclude anesthesia or RT
• Failure to meet minimum laboratory or clinical thresholds

Client Benefits

The goal of this study is to improve your cat’s chronic inflammatory bowel disease (CIE). We expect that radiation therapy may help control symptoms and could allow your cat to reduce—or even stop—other medications, such as anti-inflammatory or immunosuppressive drugs. We hope that most cats will experience either full remission or at least improvement in symptoms and medication needs for at least 6 months, with early evidence suggesting benefits may last over a year. The study also uses lower radiation doses than those previously tested in cats, which may help reduce side effects while still providing benefits.

You will be responsible for the costs of any tests done before enrollment, including:

• Upper and lower G.I. endoscopy with gastrointestinal biopsies
• A full abdominal ultrasound within 2 months prior to enrollment
• Bloodwork (CBC, chemistry, thyroid levels) within 2 months prior to enrollment
• Special diet or any medications your cat has been receiving
• Fecal flotation and FeLV/FIV serology recommended (but not required) for study
• Heart health screening test (ProBNP test, echocardiography) if heart issues are noted
• A CT scan for radiation planning is optional, and is not covered by the study if you elect to pursue this option.

The study, funded by the Tufts Zeolla Feline Research Fund, will cover all costs related to:

• Sample collection and laboratory testing during the study
• Appointment fees, anesthesia, and sedation
• Radiation therapy, up to $2300
• Ultrasound imaging (focal G.I. tract)
• Costs associated with adverse events, up to $550

Sample or Data Requirements

Your cat will undergo 3 blood tests/diagnostics prior to and after the course of treatment with the purpose of monitoring general health and organ function, and collect serum for gastrointestinal-specific analyses. These blood draws amount to approximately 2 teaspoons of blood at each visit. A total of 3 urine sample will be collected via cystocentesis (needle sampling) at each of these visits. We will also obtain a baseline gastro-intestinal focused ultrasound before and two months after the treatment, to monitor any changes to intestines and pancreas. The ultrasound procedure is non-invasive and will be performed under sedation, as needed based on your pet’s compliance.

Your cat’s treatment for CIE will involve a single course of low-dose radiation therapy to the whole abdomen. A total of 3 (minimum) to 5 (maximum) treatment sessions will be delivered once daily on consecutive business days with a machine called linear accelerator. Each radiotherapy treatment session will be delivered under a brief general anesthesia (approximately 20-40 minutes) to ensure your cat’s safety and accurate treatment delivery. Cats enrolled will undergo physical examination by a veterinarian at each visit to ensure they are healthy and cleared to undergo general anesthesia for treatment each day. A CT scan of the abdomen may be done to create a detailed 3‑dimensional map, however this not required. This helps the treatment team plan the radiation more precisely, which may reduce the risk of side effects to organs like the liver and kidneys, but it is not necessary for the current study.

Your cat will need to fast (no food) starting the night before each treatment session, but water should always be available. Fasting helps reduce the risk of complications from sedation or anesthesia, such as vomiting, regurgitation, and inhaling stomach contents into the lungs (aspiration pneumonia). A small treat or pill pockets are allowed early in the morning for administration any medications. Following each session, your cat can return home and resume normal daily activities.

Your cat may have a small area of fur shaved so that small marks can be applied.These marks help the veterinary team position your cat accurately and consistently for each radiation treatment.

Your cat will need to come in for:

1. Pre-RT consult, exam, lab work and ultrasound (within 2 weeks of start or RT)
2. Daily RT, consisting of 3 to 5 sessions on consecutive days
3. 2-week post-RT recheck for exam and lab work
4. 8-week post-RT recheck for exam, lab work and ultrasound

Contact Information

For questions regarding the clinical trial, please email clinicaltrials@tufts.edu.