To check if CAR-T cell therapy has worked for multiple myeloma, leukemia, or lymphoma, doctors use a combination of blood tests, bone marrow biopsies, imaging, and clinical assessments. The specific method depends on the type of cancer:

General Markers of CAR-T Effectiveness (All cancers)

  1. Reduction or disappearance of cancer cells in blood, bone marrow, or lymph nodes.
  2. Return of normal blood counts (especially for leukemia).
  3. No new lesions or tumor growth on imaging scans.
  4. Minimal Residual Disease (MRD) negativity – a key sign of deep remission.
  5. Clinical improvement – symptoms improve or disappear.

For Each Disease:

Acute Lymphoblastic Leukemia (ALL)

  • Bone marrow biopsy is the main test.
  • Flow cytometry or PCR is used to check for MRD (Minimal Residual Disease).
  • MRD-negative status indicates a very good response.
  • Blood tests may also show normalization of white cells and absence of blasts.

Lymphoma (e.g., DLBCL, follicular, mantle cell)

  • PET-CT scans are the gold standard to evaluate response.
  • Complete metabolic response (no uptake in PET) suggests remission.
  • Physical exam and blood markers (LDH, ESR, etc.) may support findings.

Multiple Myeloma

  • Blood and urine tests for M-protein (monoclonal protein).
  • Serum free light chain assay.
  • Bone marrow biopsy to assess for residual myeloma cells.
  • Imaging (PET-CT or MRI) to check for active bone lesions.
  • MRD testing (flow cytometry or NGS) is increasingly used to check for deep response.

When Are These Tests Done?

  • 1 month post-infusion, then regularly (every 1–3 months).
  • Frequency decreases over time if patient remains in remission.
  • Long-term monitoring is essential to detect relapse early.