To report a case of metastatic extramammary Paget’s disease (mEMPD) treated with trastuzumab deruxtecan, emphasizing the treatment's context in a patient with low Her2/neu expression.
Approach:
Case Presentation: A 73-year-old man with mEMPD and low Her2/neu expression was treated with trastuzumab deruxtecan after initial therapies, including trastuzumab and pembrolizumab, failed to show clinical response.
Key Findings:
The patient exhibited a partial response to trastuzumab deruxtecan, with regression of lymphadenopathy and bladder lesions.
Next-generation sequencing revealed a high tumor mutation burden and mutations in ERBBR2, PIK3CA, and PTEN.
Interpretation:
The case suggests that mEMPD with low Her2/neu expression and high tumor mutation burden may respond to anti-Her2/neu antibody-drug conjugates, but further studies are needed to confirm this.
Limitations:
The study is based on a single case report, limiting generalizability.
Lack of long-term follow-up data on the patient's response to treatment, which may affect the interpretation of efficacy.
Conclusion:
Trastuzumab deruxtecan may be a treatment option for mEMPD, particularly in cases with specific molecular characteristics, but further research is necessary to establish its effectiveness.
