A third generation CAR lentiviral construct containing both CD28 and 4-1BB costimulatory molecules, with an Fc fragment inserted between the CD33 single chain variable fragment (scFv) and CD28 to detect transduced CAR cells. The NK-92 cells were transduced with the above- mentioned CD33- CAR vector with an efficiency over 90%.
14-year-old girl diagnosed with AML1-ETO(+), C-KIT(+), M4 AML (intermediate risk). She attained complete remission (CR) after idarubicine (IDA) plus Ara-C (IDA 12 mg/ m2/d × 3 d and Ara-C 100 mg/m2/d × 7 d).
She received allo-HSCT from an unrelated 10/10 HLA-matched donor in July 2015. However, 15 months post-transplantation, the patient suffered from pain and swelling in the right elbow and right leg. PET-CT scan imaging showed that several hypermetabolic lesions in the right elbow joint, left knee joint, and right knee joint. Skin biopsy of the right leg revealed extramedullary infiltration of AML with 99.8% CD33+ expression.
After chemotherapy with high dose cytarabine combined with mitoxantrone (MTZ), the patient
received 3 doses of CD33-CAR NK-92 infusion in December 2017: 3×108, 6×108 and 1×109 cells on days 1, 3, and 5, respectively. The number of CAR NK-92 cells in the peripheral blood were 4 × 102/ml, 3.6 × 103/ml and 2.9 × 103/ml on days 3, 5, and 8 post-infusion. The patient suffered a moderate fever (38.5°C) on the next day following the second infusion that abated one day later.
One month following CAR NK cell treatment, BM evaluation showed 0% blasts. MRD was 1.7 × 10-3 with 88.2% CD33+ expression. AML1/ETO and WT1 copy numbers decreased to 308 and 12 per 10,000 ABL, respectively.
24-year-old male diagnosed with M4 AML containing chromosomal abnormality t(3;16). He received two courses of HAG chemotherapy leading to complete remission, followed by 10 cycles of consolidation therapy with various regimens. After 5 years, the patient relapsed with extramedullary infiltration of leukemia cells in his eyes. After local radiotherapy and high-dose cytarabine chemotherapy, the local lesion improved. One year after, his disease relapsed with 8% blasts in the BM, and WT1 was 8,000 per 10,000 ABL. He received multiple chemotherapy treatments, but complete remission was not achieved.
A year after, the bone marrow examination showed 27% blasts with 20.4% CD33+ expression. After chemotherapy with FLAG regimen, he received three doses of irradiated CAR NK-92 cells:
3 × 108, 6 × 108, and 1 × 109 cells on days 1, 3, and 5, respectively. CAR NK-92 cells in the
peripheral blood were detected at 7.4 × 103/ml, 7.6 × 103/ml, and 2.9 × 103/ml at days 3, 5, and 8 post-first infusion.
Interleukin (IL)-17A and IL-10 were substantially elevated on day 6 (following the third infusion), whereas IL-6, IL-2, IL-4, TNF-α, and IFN-γ were not changed. A moderate fever (38.5°C) was observed after infusion on day 1 but returned to normal by day 2. The patient presented with only grade I CRS. One month following CAR NK-92 infusion, bone marrow examination showed 75% blasts with 49% CD33+ and 45.8% CD123+ expression. Two months after CAR NK-92 infusion, the patient received allo-HSCT from an unrelated donor and achieved CR. He unfortunately relapsed 4 months after allo-HSCT.
These optimized the off-the-shelf CAR NK-92 cells provide a novel treatment option that is clinically advantageous and much more cost-effective compared to CAR T cells. These phase I study did not demonstrate obvious clinical efficacy, yet this first-in-man clinical trial showed that this therapy can be safely used in RR-AML patients with high tumour burden.