Autologous Hematopoietic Stem Cell Infusion for Prolonged Cytopenia After CAR-T Cell Therapy

Inclusion criteria

• Ability to understand and willingness to sign a written informed consent form (ICF).
• Age ≥ 18 years.
• Diagnosis of multiple myeloma according to the International Myeloma Working Group (IMWG) criteria.
• Prior treatment with CAR-T cell therapy and currently in remission or, in the opinion of the investigator, with refractory/progressive disease not requiring salvage therapy.
• Presence of grade 3-4 cytopenia (absolute neutrophil count < 1.0 × 10⁹/L, or platelet count < 50 × 10⁹/L, or hemoglobin < 80 g/L) either persisting or newly developed between day 30 and day 90 after CAR-T cell infusion; or deemed suitable for inclusion by the investigator based on clinical judgment.
• Availability of ≥ 1 × 10⁶/kg autologous hematopoietic stem cells in reserve.

Exclusion criteria

• Known intolerance, hypersensitivity, or contraindication to autologous hematopoietic stem cell infusion.
• Active hepatitis B or hepatitis C virus infection.
• Known HIV infection.
• Life expectancy <6 months.
• Woman who are pregnant or breastfeeding.
• Evidence of uncontrolled dysfunction of heart, lung, brain, and other important organs.
• Any other conditions that are not eligible for the trial in the judgement of the principal investigator.