Following the final HXTC infusion in Step 5, participants will move into Step 6 for a minimum of 6 additional visits at weeks 13, 17, 21, 33, 45, and 57 after the 1st HXTC infusion. The 3rd and final leukapheresis will occur at Week 21 (Step 6, Visit 22), approximately 9 weeks after the last HXTC infusion to evaluate the effect of study treatment on IUPM by QVOA.