Wearable-Triggered Digital Safety Net for Real-Time Monitoring & Intervention in Leptomeningeal Metastasis

This research study is for participants diagnosed with leptomeningeal metastasis disease (LMM), a condition where cancer has spread to the fluid and membranes surround the brain and spinal cord. The purpose of this study is to find out whether a consumer Smartwatch can continuously monitor the participant's health and detect early signs of neurological decline and whether sending an automatic alert to the participant's doctor when a change is detected can help reduce the number of participant hospitalizations.

Inclusion Criteria: * Participants must have leptomeningeal metastasis (LMM) diagnosed per clinical, imaging, and/or CSF/cytology criteria (cytology, flow cytometry, or circulating tumor DNA), arising from any solid or hematologic tumor primary. * Participants must be undergoing active anti-cancer therapy (systemic, intrathecal, and/or radiation) or active surveillance for LMM. * Age ≥18 years at the time of study enrollment. Because no safety or dosing data are available for wearable monitoring studies in children with LMM, participants under 18 years of age are excluded. * Karnofsky Performance Status (KPS) ≥50 at time of study enrollment \[See Appendix I\], to ensure feasibility of wearing the device for ≥10 hours/day. * Participants must have access to a compatible smartphone: * iPhone running iOS 16 or higher and willingness to wear Apple Watch ≥10 hours/day; OR * Android smartphone compatible with the study application and willingness to wear Samsung Galaxy Watch ≥10 hours/day. * Ability to provide informed consent (or a legally authorized representative \[LAR\] is available and willing to provide consent on the participant's behalf, if appropriate). Exclusion Criteria: * Anticipated life expectancy \