SX-682 + Proton Craniospinal Irradiation

Patients will receive SX-682 200 mg by mouth twice a day up to cycle 3. Subsequently, all patients will receive systemic therapy of the investigator's choice.

The total prescribed dose will be 30Gy (RBE) in 3Gy (RBE) daily fractions.

The researchers are doing this study to find out whether SX-682 in combination with proton craniospinal irradiation (pCSI) is a safe treatment approach for people with melanoma or non-small cell lung cancer (NSCLC) with leptomeningeal disease (LMD). The researchers will also look at whether the treatment combination is effective against participants' cancer.

Live record on ClinicalTrials.gov →

• Written informed consent
• Positive CSF cytology for malignancy and/or positive CSF circulating tumor cells
• CSF cytology with suspicious cells is considered positive; CSF cytology with atypical cells is considered equivocal and not positive
• Unequivocal radiographic diagnosis of leptomeningeal metastasis on contrast- enhanced MRI
• Patients may receive steroids to control symptoms related to CNS involvement, but the dose must be <= 8 mg per 24 hours of dexamethasone (or the equivalent). Patient's symptoms should experience stability of neurological symptoms for at least 7 days, or on a tapering dose of steroids Patients must have a confirmed pathological diagnosis of a metastatic or recurrent melanoma or non-small cell lung cancer

Inclusion criteria as written on the registry, trimmed. The full list, with exclusions, is on the live record.