- Right-sided breast cancer, cT2 cN1 (≥4 lymph nodes) cM0, first diagnosis 08/2024
- Sigmoid colon cancer, pT1 pN0 M0, first diagnosis 09/2024
- 08/2024: Diagnosis of right breast cancer cT2 cN1 cM0
- 09/2024: Neoadjuvant chemotherapy: 4 cycles epirubicin/cyclophosphamide, followed by 12 cycles paclitaxel/carboplatin and pembrolizumab
- 06/2025: Right mastectomy and axillary dissection
- 09/2025: Radiotherapy
- 09/2025: Onset of immune-related colitis CTCAE grade 3
Colonoscopy in 10/2025 showed florid ileocolitis consistent with immune-mediated colitis, while infectious causes were excluded. High-dose intravenous steroids induced only transient improvement, and subsequent infliximab therapy resulted in temporary symptom control followed by relapse. Vedolizumab induction was started in early 2026 but initially showed limited effect. Because of persistent steroid- and infliximab-refractory disease, extracorporeal photopheresis (ECP) was initiated, leading to gradual clinical improvement within 2 weeks with reduced stool frequency.
Given the severe, steroid-refractory course requiring multiple lines of immunosuppression, re-challenge with pembrolizumab is currently not recommended. Restart of immune checkpoint therapy could only be considered in exceptional cases after sustained resolution of toxicity and careful multidisciplinary risk–benefit assessment.
This case illustrates a severe and refractory immune-related colitis with partial response to vedolizumab and ECP. It highlights the diagnostic challenges in patients with altered bowel anatomy and underscores the importance of individualized multidisciplinary management in complex immune-related toxicities.
