Descartes-15 for Patients With Relapsed/Refractory Multiple Myeloma

Inclusion Criteria * Patients must be 18 years of age or older at the time of enrollment. * Patients must be diagnosed with active and measurable relapsed/refractory multiple myeloma. * Patients must have failed at least 3 prior lines of therapy which must have included an immunomodulatory drug, a proteasome inhibitor, and an anti-CD38 drug or biologic. Failure of treatment and measurable myeloma disease are defined as per 2016 IMWG criteria. * Patients must have clinical performance status of ECOG 0-2. * Patients must have adequate vital organ function as defined by: * Hemoglobin ≥8 g/dL * Absolute neutrophil count \> 1000/ mm3 * Platelets \> 50,000/mm3 * ALT/AST levels lower than 3-fold of normal * Creatinine clearance ≥45 mL/min/1.73 m2 * Normal cardiac and pulmonary function * No thromboembolic events in the past 3 months * No heparin allergy or active infection Exclusion Criteria * Patients who have any active and uncontrolled infection. * Ongoing treatment with chronic immunosuppressants (e.g., cyclosporine or systemic steroids above 40 mg/day prednisone equivalent). * Patients who have active central nervous system disease.