A 24-year-old man was diagnosed with cortical T-ALL. At onset, white blood cells count was 2,110/µL, while bone marrow (BM) was with 89% of lymphoblasts. The leukemic cells were positive for CD2, CD3, CD4, CD8, CD7, CD1α and cytoplasmic CD3, but negative for B-cell and myeloid cell markers with flow cytometry (FCM) analysis. Chromosomal karyotyping revealed a normal karyotype of 46, XY, but T-cell receptor (TCR) rearrangement confirmed by polymerase chain reaction revealed T-cell clonality. The brain CT scan revealed negative, while lumbar puncture test showed no increased cells or protein level in cerebrospinal fluid (CSF). All tests above ruled out initial CNS involvement. After induction chemotherapy regimen, initial response evaluation achieved complete remission. He then received two cycles of consolidation regimen, while FCM monitoring for minimal residual disease (MRD) revealed 1.92% lymphoblasts. [7–8] MRD assessment remained persistently positive, so the patient intended to receive peripheral blood SCT with his elder sister as a human leukocyte antigen (HLA) identical sibling donor.
However, 10 days after a high-dose intravenous methotrexate and cytarabine regimen before SCT, he developed a sudden onset of blepharoptosis of right eye with left deviation of mouth.  These signs lasted for seconds each time. Diagnostic lumbar spinal puncture was performed immediately. The cells count in CSF was 2/µL, with no leukemic cells observed. IT triple therapeutic infusion of methotrexate 10 mg, cytarabine 30 mg, and dexamethasone 5 mg was administered concomitantly at this diagnostic lumbar puncture. The symptoms were shortly relieved. On basis of neurological symptoms and therapeutic response, diagnosis of CNS relapse was made. Subsequently he received systemic chemotherapy of high-dose methotrexate plus IT triple therapeutic infusions twice weekly. The neurological symptoms were obviously relieved. The BM MRD revealed down to 0.25%.
The conditioning regimen comprised whole brain and total spinal cord radiotherapy, venetoclax, hydroxycarbamide, cytarabine, busulfan, cyclophosphamide and Methyl-CCNU. The prophylaxis of graft-versus-host disease (GVHD) included mycophenolate mofetil, cyclosporin, and short-term methotrexate. The engraftment was confirmed without complications. He developed no acute or chronic GVHD. The FCM monitoring for MRD achieved persistent negative remission, with complete donor chimerism in BM and peripheral blood.
On day 83 post-SCT, his left eye developed esophoria with limited abduction and double vision, which was similar to previous manifestations. Lumbar spinal puncture showed increased CSF pressure and cell counts. The exfoliative cytology showed that leukemic blasts were easily to be seen, while FCM analysis revealed 87% of lymphoblasts. After cycles of high-dose methotrexate plus repeated IT triple therapy twice weekly, cell counts in CSF decreased to 2/µL. Meanwhile his neurological signs improved. During this process, the MRD monitoring through FCM revealed persistently negative. No lymphoblasts were found with complete donor chimerism both in BM and peripheral blood.
His neurological symptoms got worse again 4 weeks later. The patient developed progressive paraplegia without urine and feces incontinence. To treat myelitis, the patient received intravenous immunoglobulin and methylprednisolone. However, the neurological signs were not obviously improved. He had already received a therapeutic radiotherapy and many cycles of systemic chemotherapy with IT injection. We therefore performed IT DLI in dose of 1.23×109/L. But IT DLI had limited efficacy and his neurological signs seemed no obvious improvement. In the meantime, he developed progressive legs numbness or weakness and activity obstacle.
On day 131, we performed IT umbilical cord blood-derived CAR-NK cells infusion (NK cells count 1.0×107/L). The donor lymphocytes and CAR-NK cells were prepared using a local distributed, standardized, automated system at the cell processing center of Hebei Senlang Biotechnology Company under good manufacturing practice conditions. The institutional review board of Hebei Medical University approved the study protocol, and the patient provided written informed consent. After IT CAR-NK infusion, he developed high fever, headache, nausea and vomiting. Three days later, he developed a spinal cord transection with incontinence. Physical examination revealed absence of touch and pain sensation below the level of the third lumbar vertebra. Muscle strengths of lower extremities declined to class zero. Magnetic resonance imaging of brain and spinal cord revealed subacute combined degeneration. Detection of cytokines revealed that interferon-γ, interleukin-6 and interleukin-8 increased in CSF. After IT CAR-NK cells infusion, his limb numbness and movement disorder got worse in a short time, whereas the ptosis and blurred vision improved completely. BM and blood simultaneously remained CR and complete donor chimerism over nine months after IT CAR-NK cells infusion.