Study of KYV-101 Anti-CD19 CAR T Therapy in Adult Dermatomyositis

The goal of this clinical trial is to characterize to understand the effects of a type of cell therapy called Chimeric Antigen Receptor T lymphocyte (CAR T) therapy in adult patients with the autoimmune disease dermatomyositis. This study will utilize a technology that modifies a type of white blood cell called the cytotoxic T lymphocyte-this T cell normally functions in the immune system to kill infected or potentially harmful cells in the body. In CAR T therapy, the patients' white blood cells are harvested and the cytotoxic T cells are isolated and modified such that they are programmed to kill any cell that has a protein structure called "CD19" on its outer surface (membrane). Since the CD19 protein is only present on a type of white blood cell called the B lymphocyte, when these "re-engineered" cytotoxic T lymphocytes are then given back to the patient (by an infusion), these cells will seek out and kill essentially all of the patient's B cells. B cells are an important part of a person's immune system and have many functions, including the production of antibodies. It is thought that, in dermatomyositis and other autoimmune diseases, a tiny subset of these B cells plays a large role in making autoantibodies (antibodies directed against the patient's own tissues) and causing disease. The idea is that the therapy will "wipe out" all/most of the B cells in the patient so that they can make an entirely new set of B cells to recreate a functional immune system without the autoimmune disease. The main questions the study intends to answer are: * Understanding how well patients tolerate undergoing this therapy in terms of side effects; * Getting an early idea if this therapy can help certain aspects of the autoimmune disease, including inflammation in the skin, muscles, and lungs;