INNV-42. INTRA-ARTERIAL MELPHALAN FOR HISTIOCYTIC NEOPLASMS INVOLVING NEUROLOGIC, OCULAR, AND HEAD AND NECK STRUCTURES

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Abstract BACKGROUND Histiocytic neoplasms are clonal hematopoietic disorders of myeloid lineage. Involvement of neurologic structures by histiocytic infiltration or disease-associated neurodegeneration (ND) represents a severe disease phenotype associated with morbidity and mortality. Despite recent advances with BRAF and MEK inhibitors, patients with neurohistiocytic involvement continue to demonstrate suboptimal outcomes. Intra-arterial chemotherapy (IAC) may represent an effective therapy for this disease manifestation. METHODS Patients with biopsy-proven histiocytic neoplasms involving neurologic, ocular, or head and neck structures were treated with intra-arterial melphalan delivered via selective catheterization of tumor arterial vasculature. Patients treated had refractory/persistent tumorous disease or progressive functional decline despite BRAF/MEK inhibition, or had limited disease appropriate for local therapy. Patients were evaluated for radiologic (PET or CT/MRI) response and functional neurologic response with quantified ataxia and dysarthria scales, or change in visual acuity (VA), as appropriate. Procedure-related adverse events as well as clinical and laboratory toxicities were captured. RESULTS 74 IAC treatments were administered to 17 patients, 12 with tumorous disease (6 Rosai-Dorfman disease; 3 xanthogranuloma; 3 Langerhans cell histiocytosis[LCH]; 1 Erdheim-Chester disease [ECD]), 5 with ND-LCH/ECD, and ten with disease-related impairment of VA. Patients received a range of 2-12 IAC doses. 9/12 (75%) patients with tumorous disease had complete or partial radiologic response. 4/5 patients with ND had measurable improvement in dysarthria and 2/5 had measurable improvement in ataxia. 4/10 patients had improved VA. Of all patients with clinical or radiologic response, three have experienced disease recurrence since IAC in long-term follow-up. No procedural adverse events were observed, 1 patient had neutropenia and 1 patient melphalan hypersensitivity. CONCLUSIONS IA melphalan is a safe and robustly effective treatment option for tumorous and ND histiocytic neoplasms of neurologic, ocular, and head and neck structures.