Inclusion Criteria:  Participants must be planning to receive ICI-based therapy for a solid tumor malignancy. This therapy must be given according to Food and Drug Administration (FDA) label or National Comprehensive Cancer Network (NCCN) guidelines at Category 1 or 2A and not in the context of a clinical trial Participants who have received prior ICI-based therapy must have completed ICI based therapy at least 180 days prior to registration Participants must not have discontinued any prior ICI-based therapy (if applicable) because of irAE Participants must not have received chemotherapy, biologic, or targeted-therapy within 21 days prior to registration  Participants must have recovered from side effects of prior therapy to the following standards per treating physician's discretion:  =< Grade 1 for any non-hematologic side effects (excluding neuropathy and alopecia); lab-related parameters of liver and renal function will be considered at the discretion of the treating physician) =< Grade 2 for neuropathy and/or alopecia Grade 3 or less for any hematologic side effects Participants must be planning to begin standard of care ICI-based therapy within 3 calendar days after registration Participants must not be planning to receive ICI-based therapy in combination with chemotherapy or any other non-ICI therapy for treatment of their cancer Participants must be at least 18 years of age Participants must complete their history and physical examination within 28 days prior to registration Participants who can complete the S2013 Feasibility Questionnaire in English or Spanish must participate at the scheduled assessments Participants must be able to complete Patient-Reported Outcome (PRO) instruments in English, Spanish, or French and must be planning to complete PROs at all scheduled assessments Participants must complete the pre-registration (baseline) PRO forms within 14 days prior to registration  Participants must be willing to participate in PRO data collection  Note: Prior to registration, participants must decide on their method (paper or electronic) of completing their follow-up questionnaires. Participants who elect electronic (ePRO) completion must have an iPhone, Android phone, or tablet with cellular or WiFi connectivity in order to download the Patient Cloud mobile applications onto the device (personal device or a site provisioned device for multi-users) Participants must be offered the opportunity to participate in the optional specimen banking  Note: As a part of the OPEN registration process the treating institution's identity is provided in order to ensure that the current (within 365 days) date of institutional review board approval for this study has been entered in the system.  Participants must be informed of the investigational nature of this study and must sign and give informed consent in accordance with institutional and federal guidelines