CD133-directed CAR T cells for advanced metastasis malignancies: A phase I trial

Abstract

Expressed by cancer stem cells of various epithelial cell origins, CD133 is an attractive therapeutic target for cancers. Autologous chimeric antigen receptor-modified T-cell directed CD133 (CART-133) was first tested in this trial. The anti-tumor specificity and the postulated toxicities of CART-133 were first assessed. Then, we conducted a phase I clinical study in which patients with advanced and CD133-positive tumors received CART-133 cell-infusion. We enrolled 23 patients (14 with hepatocellular carcinoma [HCC], 7 with pancreatic carcinomas, and 2 with colorectal carcinomas). The 8 initially enrolled patients with HCC were treated by a CART-133 cell dose escalation scheme (0.05-2 × 106/kg). The higher CAR-copy numbers and its reverse relationship with the count of CD133+ cells in peripheral blood led to the determination of an acceptable cell dose is 0.5-2 × 106/kg and reinfusion cycle in 23 patients. The primary toxicity is a decrease in hemoglobin/platelet (≤ grade 3) that is self-recovered within 1 week. Of 23 patients, three achieved partial remission, and 14 achieved stable disease. The 3-month disease control rate was 65.2%, and the median progression-free survival was 5 months. Repeated cell infusions seemed to provide a longer period of disease stability, especially in patients who achieved tumor reduction after the first cell-infusion. 21 out of 23 patients had not developed detectable de novo lesions during this term. Analysis of biopsied tissues by immunohistochemistry showed CD133+ cells were eliminated after CART-133 infusions. This trial showed the feasibility, controllable toxicities, and effective activity of CART-133 transfer for treating patients with CD133-postive and late-stage metastasis malignancies.

Keywords: Adoptive T cell therapies; CD133; advanced metastasis malignancies; autologous T cells; chimeric antigen receptor (CAR); phase I trial; therapeutic trials.

Figures

Figure 1.

Treatment plan and treatment protocol. (A) Schematic representation of the CAR-133-CD137ζ chimeric T-cell receptor cDNA plasmid, not to scale. (B) Consort flow diagram of the clinical trial. (C) One standard cycle of CART-133 treatment procedure. CART-133 treatment for non-HCC patients included a chemotherapy pre-regimen (red dashed line).

Figure 2.

CART-133 cell dose escalation. (A) Dose group and CART-133 infusion cell dose pattern in all patients. (B) Hemoglobin (Hgb), reticulocyte, CD133+ cells and CAR-gene copy numbers in PB were detected before and at serial time points after CART-133 cell infusion in each patient from every cohort. (C) Tumor biomarkers in serum from each patient were detected before and at serial time points after CART-133 cell infusion. The blue dashed line on the plots is the normal range of each tumor biomarker. Red represents the increase, and green represents the decrease. N = cell infusion cycle; n = case number.

Figure 3.

Safety of CART-133 cells. Cytokines from the serum of each patient's PB, which was collected before and at serial time points after cell infusion, was measured by fluorescence-activated cell sorting. The color shades represent different fold-changes with the baseline.

Figure 4.

Response of CART-133 cells. (A) Maximum reduction in target lesion size after CART-133 cell infusion. PD: progressive disease, SD: stable disease, PR: partial remission. (B) Progression-free survival and overall survival by the Kaplan-Meier method. (C) Patients were divided into 3 groups based on response from the first cell infusion. PR + SD (lesion-regression), SD (lesion-progression), PD (progressive disease). Statistical analysis of PFS differences between the 3 groups.

Figure 5.

Special presentations. (A) Immunohistochemical examination (diaminobenzidine with hematoxylin counterstaining) of a punch biopsy of liver lesion from patient 12 before and 41 weeks after the first CART-133 cell infusion. (B) Immunohistochemical examination of patient 14 before and 30 weeks after the first CART-133 cell infusion showed that tumor cells were CD133- after cell infusion. Notably, scattered CD3+ and CD8+ cells infiltrated the tumor after infusion, and CD34+ cells significantly decreased. (C) Left: Representative tumor response images for patient 15 before and after CART-133 cell infusion, contrast-enhanced MRI scans show pancreas and liver lesions reduced significantly 4 weeks after the first CART-133 cell infusion and remained reduced after the second cell infusion. Right: CD133+ cells in PB, CAR-gene copy numbers in PB and cytokines in serum were detected before and at serial time points after CART-133 cell infusion in patient 15.

Figure 6.

Biological evidence of CART-133 cells. (A) Quantitative real-time PCR was performed on genomic DNA harvested from each patient's PB mononuclear cells collected before and at serial time points after CART-133 cell infusion, using primers specific for the transgene. CD133+ cells count change from baseline in the blood after the infusion of CART-133 cells in 21 patients. CART-133 cell infusion in cohort 1 with * is shown. (B) CAR-gene copy numbers analysis from 22 patients (except patient 11, who refused to offer blood for detection) before and during the 1 month after cell infusion; the number of CART-133 cell infusion cycle was 41. (C) Patients were divided into 4 groups based on time of duration of PFS.