Case Report: Observational use of mycophenolate mofetil in probable steroid-unresponsive immune checkpoint inhibitor-associated transverse myelitis

Our plain-English summary of Case Report: Observational use of mycophenolate mofetil in probable steroid-unresponsive immune checkpoint inhibitor-associated transverse myelitis, by L. Kong, X. Wang, T. Yu, et al (Frontiers in Immunology, 2026).

The study

• Authors: L. Kong, X. Wang, T. Yu, J. Wang, C. Yang, L. Zhang, D. Zhong
• Journal: Frontiers in Immunology
• Published: 2026;17:1933514
• Type of article: Case report
• Read it: PubMed · Publisher · Free full text

Abstract

Immune checkpoint inhibitor (ICI)-associated transverse myelitis (TM) is a rare and severe neurological immune-related adverse event (n-irAE) with an incidence of < 0.01%, and the clinical management of steroid-unresponsive cases remains extremely challenging. This article reports the case of a 37-year-old male patient with biphasic pleural mesothelioma who developed ICI-associated TM after treatment with nivolumab combined with ipilimumab. Initial treatment with high-dose glucocorticoids plus intravenous immunoglobulin (IVIg) was ineffective. After mycophenolate mofetil (MMF) was added in combination with steroids for 1 month, the patient's neurological function showed slight improvement, and intramedullary contrast-enhanced signals on spinal MRI showed partial reduction. However, spinal cord cystic or myelomalacic changes suggested potentially irreversible parenchymal injury. Currently, the patient has restarted pemetrexed combined with carboplatin chemotherapy, and the disease status is stable. Based on recently published case series, case reports, and systematic reviews, this article discusses the second-line treatment strategies for steroid-unresponsive ICI-associated TM, aiming to provide a reference for clinical practice in managing such rare cases.

Copyright © 2026 Kong, Wang, Yu, Wang, Yang, Zhang and Zhong.

In plain English

This was a case report from a hospital in Tianjin, China, describing one 37-year-old man with biphasic (epithelioid-predominant) pleural mesothelioma. From August to October 2025 he received four cycles of the immune checkpoint inhibitors nivolumab and ipilimumab. In November 2025 he suddenly developed weakness and abnormal sensation in both legs and became unable to urinate on his own. A team of specialists favored a diagnosis of transverse myelitis (spinal cord inflammation) caused mainly by these drugs. Other contributors could not be ruled out, including an anti-Ri antibody in the blood and Epstein–Barr virus genetic material in spinal fluid. Intravenous immunoglobulin and high-dose steroids brought limited benefit. After mycophenolate mofetil (MMF) was added to steroids, leg strength improved from Grade I to Grade II at one month and spinal MRI showed partly reduced inflammation. He still could not urinate on his own, and the MRI showed cystic or myelomalacic changes. The authors concluded that MMF's own contribution could not be separated from concurrent changes in steroid dose, so a single case cannot establish MMF as an acute rescue treatment. The article does not discuss asbestos.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: case report (one patient), with a discussion of previously published cases
• Who was studied: One 37-year-old man with no previous medical history and no smoking or alcohol history, treated at Tianjin Medical University General Hospital, China. Biphasic (epithelioid-predominant) pleural mesothelioma was diagnosed after thoracoscopic resection in July 2025. Follow-up ran into January 2026.
• Exposure: Immune checkpoint inhibitor treatment: nivolumab 360 mg every 3 weeks plus ipilimumab 50 mg every 6 weeks, four cycles from 5 August to 21 October 2025. He also had one cycle of pemetrexed plus carboplatin on 14 November 2025, before symptom onset. Asbestos exposure is not addressed.
• Main results:
  • On 20 November 2025 the patient developed weakness and sensory abnormalities in both legs. On admission he had completely lost the ability to urinate on his own, which the authors describe as urinary retention.
  • A multidisciplinary team favored immune checkpoint inhibitor-associated transverse myelitis as the main cause but could not fully rule out mixed contributions. The patient had serum anti-Ri antibody positivity and Epstein–Barr virus reads detected in cerebrospinal fluid.
  • Intravenous immunoglobulin, 25 g daily for 5 days, gave a limited clinical response.
  • During methylprednisolone treatment, right lower limb strength improved from Grade I to Grade II. Symptoms then remained unchanged after the switch to tapering oral prednisone.
  • With methylprednisolone 80 mg daily plus MMF 0.5 g twice daily, sensation in the right lower limb partly recovered.
  • With oral prednisone 50 mg daily plus MMF, left lower limb strength improved from Grade I to Grade II.
  • At one month, the band-like sensation around the waist had not improved.
  • At one month, the patient's ability to urinate on his own had not recovered.
  • Spinal MRI on 19 January 2026 showed partial reduction in inflammation. It also showed cystic or myelomalacic changes in the affected cord, which the authors said suggest potentially irreversible injury.
  • No obvious MMF-related adverse reactions were observed.
  • After pemetrexed plus carboplatin was restarted, the patient completed two cycles. The tumor showed stable disease with no new lesions.
• The authors' conclusion: The authors concluded that partial neurological and imaging improvement occurred during combined corticosteroid and MMF treatment. They said MMF's independent effect could not be separated from the steroid changes, so this single case cannot establish MMF's efficacy for acute rescue, and more cases are needed.
• Limitations the authors state:
  • The report covers a single case with relatively short follow-up.
  • Recurrence risk may persist beyond one year after treatment.
  • Because of the anti-Ri antibody and Epstein–Barr virus findings, only a probable diagnosis, not a definite causal attribution, could be made.
  • The imaging improvement occurred during combined treatment and cannot be attributed to MMF alone.
  • There is no direct comparative evidence between MMF and other second-line treatments.

Topics

Medical terms in this study, explained in our Lexicon: checkpoint inhibitors, Biphasic Mesothelioma, Pleural Mesothelioma, Nivolumab (Opdivo), Ipilimumab (Yervoy), Pemetrexed (Alimta), Carboplatin, Chemotherapy.

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