A phase I study of immune gene therapy for patients with CLL using a membrane-stable, humanized CD154

Abstract

Ligation of CD40 on chronic lymphocytic leukemia (CLL) cells induces phenotypic and biochemical changes that facilitate CLL cell-T cell interactions and enhances the sensitivity of CLL cells to clearance by adaptive and innate immune-effector mechanisms. CLL cells can be transduced to express CD40 ligand (CD154) using a replication-defective adenovirus vector, thereby cross-linking CD40 on transduced and non-transduced, bystander CLL cells. In a previous study, patients received infusions of autologous CLL cells, transduced to express murine CD154 (mCD154), which induced anti-leukemic immune responses, but also anti-mCD154 antibodies. In this study, we report a phase I study, in which patients were infused with 1 × 10(8), 3 × 10(8) or 1 × 10(9) autologous CLL cells transduced ex vivo to express ISF35, a humanized, membrane-stable CD154. Infusions were well tolerated and consistently followed by reductions in blood lymphocyte counts and lymphadenopathy. After infusion, circulating CLL cells had enhanced or de novo expression of CD95, DR5, p73 and Bid, which enhanced their susceptibility to death-receptor-mediated or drug-induced apoptosis, including CLL cells with deletions at 17p13.1 (del(17p)). Two patients who had CLL with del(17p) had subsequent chemoimmunotherapy and responded well to treatment. In summary, infusions of autologous, ISF35-transduced CLL cells were well tolerated, had biological and clinical activity, and might enhance the susceptibility of CLL cells with del(17p) to chemoimmunotherapy.

Figures

Figure 1

Complete blood counts with manual differential were performed before and after administration of autologous ISF35-transduced cells (a). ALC was normalized to the count obtained pre-treatment on the day of infusion (day 0) and plotted for each subject by dose level. The sum product of bidimensional lymph node measurements by palpation in three nodal regions was used as the measure of lymph node bulk (b). Measures were taken pre- (day 0) and post-infusion of autologous ISF35-transduced CLL cells. These data points were normalized to day 0 and presented for each patient by dose level. Consistent reductions in normalized ALC and lymph node bulk were noted acutely following treatment.

Figure 2

Blood was taken from patients 3 and 5 pre-treatment on the day of infusion (pre) and at the indicated days after infusion of autologous ISF35-transduced CLL cells. The freshly isolated blood mononuclear cells were immediately stained for annexin V to determine the proportion of circulating cells undergoing apoptosis. Patient 3 received a single infusion and patient 5 received two infusions. Both patients had del(17p) in their leukemia cells. Both patients had an increase in the percent of circulating leukemia cells undergoing apoptosis post-infusion demonstrated by staining for annexin V that lasted for up to 3 weeks after infusion.

Figure 3

Freshly isolated blood mononuclear cell from patients 1, 2, 3 (a) and 5 (b) were obtained pre-treatment (Pre-Rx) and at the indicated days post infusion of autologous ISF35-transduced CLL cells. Immunoblot was performed to evaluate expression of the intracellular pro-apoptotic protein Bid. Circulating leukemia cell expression of Bid increased and persisted for several weeks after infusion, including for patients 3 and 5, who have leukemia cells with del(17p).

Figure 4

Circulating cells were evaluated for expression of p73 and Mcl-1 by immunoblot. Blood was obtained pre-treatment (Pre) and after infusion of autologous ISF35-transduced leukemia cells. Immediately, blood mononuclear cells were isolated and cell lysates were evaluated by immunoblot for protein expression for p73 and Mcl-1. Blots were scanned and data are expressed in relative units. Increased expression of p73 was observed in circulating cells following infusion of ISF35-transduced cells in this patient with del(17p). There was also reduction in the anti-apoptotic protein Mcl-1 after infusion.

Figure 5

Actual (measured) ALC (solid line) for patients 1, 3, 4 and 6 are shown before and after infusion of autologous ISF35-transduced CLL cells. Day 0 was the count before the treatment on the day of infusion. The predicted ALC shown by the dashed line is the projected count for each patient based on actual blood counts obtained in the absence of treatment for the time period of at least 6 months immediately before receiving ISF35-transduced cells. These data demonstrate a reduction in actual lymphocyte counts following ISF35 infusion versus the projected counts.