Combined treatment with radiotherapy, chemotherapy and avelumab results in regression of metastatic Merkel cell carcinoma and improvement of associated Lambert‑Eaton myasthenic syndrome: A case report

Abstract

Merkel cell carcinoma (MCC) is a rare and highly aggressive neuroendocrine malignancy arising from mechanoreceptors in the basal epidermis. Due to a pronounced risk of spread and a high propensity for recurrence after treatment, immediate treatment is of utmost importance. Lambert-Eaton myasthenic syndrome (LEMS) is a paraneoplastic phenomenon affecting the muscles with autoimmune pathophysiology, and >50% of known cases are associated with an underlying malignancy. In the present report, the case of a 67-year-old man presenting with progressive proximal muscle weakness, autonomic dysfunction and involuntary weight loss is described. Symptoms and detection of voltage-gated calcium channel antibodies were consistent with LEMS. Distant metastases were found in the inguinal and iliac lymph nodes, and these were immunohistochemically confirmed to be of epithelial and neuroendocrine origin, consistent with MCC. Local radiotherapy and chemotherapy improved the symptoms; however, a change of treatment was required due to the side effects of the chemotherapy. Avelumab, an immune checkpoint inhibitor, was therefore introduced, and within a year the patient did not only experience tumor remission but also exhibited marked improvements in muscle strength and mobility. At present, 2 years later, the MCC is still in remission. To the best of our knowledge, the present report is the first to describe MCC with associated LEMS, which was successfully treated with avelumab after previous radiotherapy and chemotherapy, with both improved functional motor recovery and tumor reduction. In conclusion, the present case report demonstrated that the present treatment strategy is a potential treatment option and could thus be considered in similar cases.

Durvalumab for Extensive-Stage of Small-Cell Lung Cancer With Lambert-Eaton Myasthenic Syndrome

“…To our knowledge, there were only four malignant cases who had preexisting LEMS but had Durvalumab for Lambert-Eaton Syndrome J Med Cases. 2023;14(2):71-75 been treated by ICIs [7][8][9][10]. These rare cases suggest that ICI is a possible treatment option for cancer patients with LEMS.…”

“…These treatments reduced the titer of anti-P/Q-type VGCC antibodies from 65.2 pmol/L at the diagnosis to undetectable level at the initiation of ICI. In this case, LEMS did not deteriorate by 1.5-year administration of avelumab, which was discontinued because of imAEs of hypothyroidism and drug-induced pneumonitis [ 9 ]. The Japanese case by Takigawa et al [ 7 ] presented a 73-year-old woman who maintained complete remission from localized stage of SCLC associated with LEMS 22 years earlier.…”

Merkel cell carcinoma overlapping Bowen’s disease: two cases report and literature review

“…The treatment of MCC overlapping BD adheres to the principles established for MCC treatment (Green et al 2022 ; Harvey et al 2022 ). In the management of MCC, surgical excision is often considered the primary modality of treatment.…”

Efficacy of durvalumab plus chemotherapy in small-cell lung cancer with Lambert-Eaton myasthenic syndrome

“…Dohrn et al documented the use of avelumab for Merkel cell carcinoma, which led to regression of the primary lesion but worsened neurological symptoms, after relieved with intravenous immunoglobulin (IVIG) [ 7 ]. Similarly, Green et al presented the use of avelumab for Merkel cell carcinoma, showing regression of the primary lesion and improvement of neurological symptoms [ 8 ]. Additionally, Takigawa et al administered pembrolizumab to a patient with squamous cell lung cancer as a secondary cancer with a history of SCLC-LEMS remission.…”