CAR-T therapy often becomes harder to use when kidney function is severely impaired. This case asks whether carefully reduced dosing and timed dialysis could still make the treatment possible—and reports a striking result. Acute kidney injury and chronic kidney disease are common in multiple myeloma, making kidney impairment a central problem in this case.

Fludarabine is part of lymphodepletion before CAR-T cell therapy, but it is renally eliminated and is not recommended when severe renal impairment means a glomerular filtration rate below 30 milliliters per minute per 1.73 square meters. The treatment therefore had to balance the need for lymphodepletion against severe renal impairment.

The case used fludarabine in a reduced dose, cyclophosphamide, and hemodialysis before reporting tolerance, CAR-T expansion, and complete remission beyond 12 months. Acute kidney injury and chronic kidney disease are common consequences of multiple myeloma because of hypercalcemia and light chain disease associated nephropathy.

At diagnosis, a serum creatinine level of 2 milligrams per deciliter or higher is seen in approximately 20 percent of patients. Treatment is challenging because many therapeutic agents are nephrotoxic, renally eliminated, or both. Against that background, BCMA targeted CAR-T cells, including Idecabtagen vicleucel, are the treatment context examined here.

The patient was a 58-year-old female with relapsed and refractory kappa light chain multiple myeloma who was admitted for CAR-T cell therapy with Abecma, or Ide-cel. Her disease had high-risk features, including a 4;14 translocation, and her R-ISS stage was stage II.

After several treatment regimens, including lenalidomide maintenance, local radiotherapy, daratumumab, bortezomib, dexamethasone, carfilzomib, and later bridging therapies, the disease continued to progress. At admission, she had acute kidney injury with serum creatinine of 2.69 milligrams per deciliter and an estimated GFR of 20 milliliters per minute per 1.73 square meters, alongside progressive disease.

Another regimen failed to achieve a response, while free kappa light chains increased to 15105.56 with a kappa-to-lambda ratio of 18881.95. After cyclophosphamide, etoposide, and dexamethasone, serum kappa light chains decreased to 8732.90, but kidney function improved only slightly and the GFR remained below 30 milliliters per minute per 1.73 square meters.

After quality release of ide-cel, the patient received fludarabine and cyclophosphamide using a dose-adjustment and dialysis strategy previously published for simultaneous allogeneic and kidney transplantation. Fludarabine was reduced to 15 milligrams per square meter, while cyclophosphamide was given at 300 milligrams per square meter daily for three days.

Cyclophosphamide was administered at seven in the evening and fludarabine at eight, with dialysis the following morning using a larger FX one hundred filter. The full cyclophosphamide dose was given at least 12 hours before dialysis because cyclophosphamide serum concentration is elevated in kidney disease but is partly removed during hemodialysis.

Lymphodepletion was well tolerated, and ide-cel was infused three days after the last fludarabine dose at a dose of 4 times 486.1 times 10 to the 6 cells. The patient developed grade 2 cytokine release syndrome with fever and dyspnea on day 1, successfully treated with two doses of tocilizumab.

Hematologic toxicity included grade 4 neutropenia and thrombocytopenia and grade 3 anemia, with six erythrocyte concentrates and two thrombocyte concentrates transfused. Neutropenia below 1000 microliters was present for 14 days, from day minus 1 before CAR-T infusion through day 12, and two doses of granulocyte-colony stimulating factor were applied.

Apart from symptomatic hypocalcemia with tachycardia and QT-interval prolongation, possibly associated with tumor lysis, no other severe complications were observed. The patient was discharged to outpatient care on day 17 after CAR-T cell infusion.

CAR-T cell expansion was excellent, and light chains rapidly decreased to the normal range. Serum, urine, bone marrow analysis, MRI, and PET-CT scans nine months after CAR-T cell therapy revealed complete remission. That complete remission was ongoing at the last visit one year after treatment.

In the gray curve, CAR-T cells rise from near baseline to roughly one hundred cells per microliter around day eighty, then settle near thirty by the final time point. The black free-kappa curve starts above ten thousand milligrams per liter and falls to the plot’s baseline within the early post-infusion measurements, remaining there through follow-up.

Kidney function also remained stable, with a CKD-EPI estimated GFR of 24 milliliters per minute at last follow-up. The paper also points to a timeline from the beginning of lymphodepletion in Figure 2. The timeline’s left side places fludarabine and cyclophosphamide across days minus five through minus three, with dialysis marked after each conditioning sequence.

Moving right, the figure marks CAR-T-cell infusion at day zero, tocilizumab on days one and two, discharge at day seventeen, and follow-up checkpoints extending to twelve months. Reports of CAR-T cell therapy in patients with an estimated GFR below 30 milliliters per minute per 1.73 square meters are very limited.

Hunter and Wood each reported two patients with end-stage kidney disease receiving CD19 targeted CAR-T cells. The reported approaches included reduced fludarabine doses and hemodialysis performed 12 hours later, or dialysis after the first and third fludarabine doses.

Cytokine release syndrome and ICANS were seen in three patients, information on cytopenia was not available, and all patients responded to therapy. In this patient, grade 3 thrombocytopenia was still present on day 60 after CAR-T infusion, but transfusion and granulocyte-colony stimulating factor were no longer needed.

In the Sidana study, grade 3 or higher thrombocytopenia occurred in 73 percent of patients with GFR below 30 milliliters per minute on day 60, while grade 3 or higher anemia and neutropenia were still present in 36 percent. By day 90, the Sidana study still observed grade 3 or higher anemia and thrombocytopenia in 10 and 30 percent, respectively, while this patient no longer demonstrated grade 3 cytopenias.

The case argues that CAR-T cell therapy is an important option for relapsed and refractory multiple myeloma and should also be offered to patients with severe renal impairment and an eGFR below 30 milliliters per minute per 1.73 square meters. For the first time in this report, lymphodepletion used fludarabine and cyclophosphamide followed by six hours of hemodialysis with a larger FX one hundred filter.

The patient showed excellent CAR-T cell expansion and complete remission for at least 12 months without severe toxicity events. The authors call for further investigation of fludarabine pharmacokinetics under hemodialysis and of treatment response and toxicity in a larger patient cohort.

In this single patient, dose-adjusted fludarabine and cyclophosphamide with six hours of hemodialysis were followed by excellent CAR-T expansion and complete remission lasting at least 12 months, supporting further study rather than proving a general rule.