Pembrolizumab and tavokinogene telseplasmid electroporation in metastatic melanoma

Introduction: Tavokinogene Telseplasmid Electroporation Therapy (TAVO) and Pembrolizumab therapy is being studied in subjects with immune checkpoint inhibitor (ICI) resistant melanoma. TAVO is a novel office-based local therapy shown to be effective in patients with advanced melanoma. The technique involves the direct injection of a plasmid encoding IL-12 into an accessible tumor driven by electroporation. The tumor cells have then been shown to express high levels of IL-12 resulting in a local inflammatory response within the tumor microenvironment.

Presentation of case: The patient with stage IIB, pT3b melanoma was treated with primary tumor resection and found to have a negative sentinel node biopsy. She subsequently developed regional recurrence and was treated with inguinal lymphadenectomy and adjuvant Nivolumab. Despite therapy, she had progression of disease with skin and subcutaneous metastases (in-transit lesions), brain and liver lesions, hilar and iliac nodal disease. She was transitioned to nivolumab + ipilimumab, and Talimogene Laherparepvec (T-VEC) therapy for the in-transit lesions, without success. Stereotactic radiosurgery was used for the brain metastasis. Groin subcutaneous and in-transit lesions were treated with TAVO and intravenous pembrolizumab. Serial physical exams and CT scans were used to assess response.

Discussion: All lesions treated with TAVO resolved. An abscopal response was also noted: hilar and mediastinal lymphadenopathy resolved. The liver mass and pelvic lymphadenopathy decreased in size, and her brain metastasis remained stable after radiation.

Conclusion: This case suggests that combination TAVO and Pembrolizumab is a safe and effective local treatment for ICI resistant metastatic melanoma in the setting of rheumatoid arthritis. An abscopal effect was also noted through control of systemic disease.