Vaccine Responses in Patient With Multiple Myeloma and Non-Hodgkin Lymphoma After CAR-T Treatment

This study is looking at how well vaccines work in people with certain blood cancers (like multiple myeloma or non-Hodgkin lymphoma) after they receive CAR-T cell therapy — a type of immune cell treatment. The immune system is often weakened after CAR-T therapy, and researchers want to know if vaccines can still protect these patients. **You may be eligible if...** - You are 18 or older - You have been diagnosed with multiple myeloma, diffuse large B-cell lymphoma, follicular lymphoma, mantle cell lymphoma, CLL, SLL, or primary mediastinal B-cell lymphoma - You have received or are planning to receive CAR-T cell therapy - You are willing to provide written consent **You may NOT be eligible if...** - You have not been diagnosed with one of the listed cancers - You are unable or unwilling to follow the study schedule Talk to your doctor to see if this trial is right for you.