Melphalan Intra-arterial Chemotherapy for Choroidal Melanoma Chemoreduction - a Phase I Clinical Trial

INTRODUCTION Choroidal melanoma is the most common primary intraocular malignancy in adults, thus being the focus of extensive research. The primary treatment goals of this disease consist in controlling local disease, reducing the risk of distant metastases, and avoiding enucleation whenever possible.

Plaque brachytherapy is currently the standard treatment for small and medium-sized uveal melanomas. In clinical practice, ruthenium (Ru-106) or iodine (I-125) are the most commonly employed radioisotopes. Ruthenium is the most utilized radioisotope in Europe and South America due to its availability and good clinical outcomes. It is currently the only available option in Brazil's public health system (SUS). However, its use for large tumors (greater than 10 mm in thickness and/or 22 mm in diameter) is limited by the inability of delivering an adequate therapeutic dose of radiation without causing further damage to the surrounding retinal tissue.

For this reason, researchers in medical physics have been investigating new treatment options in the last decades, including external beam radiotherapy (EBRT), radiosurgery (gamma knife or linear accelerator), and proton beam therapy. Although gamma knife radiosurgery and proton beam therapy are effective treatments with reliable tumor control rates, they are associated with poor visual outcomes, inadequate globe retention, and their use is reportedly limited in public health systems of low- or middle-income countries. EBRT carries potential side effects related to a broader radiation field, with an increased risk for complications in ocular and periocular structures, such as eyelids, sclera, lens, and retina. Finally, enucleation is an effective management for very large tumors, but it is usually a last resource.

Considering the above-mentioned treatment limitations for large choroidal melanomas, our group explored an alternative approach using intra-arterial melphalan for tumor chemoreduction, aiming to reduce thickness and allow subsequent brachytherapy using a Ru-106 plaque.

Intra-arterial chemotherapy (IAC) with melphalan has been used to treat multiple cancers, including liver metastases from uveal and skin melanomas, but it has never been described as a primary tumor treatment. Previous studies have demonstrated a reasonable safety profile of the therapy when used for the treatment of other tumors.