Lenalidomide treatment promotes CD154 expression on CLL cells and enhances production of antibodies by normal B cells through a PI3-kinase–dependent pathway

Abstract

Chronic lymphocytic leukemia (CLL) involves a profound humoral immune defect and tumor-specific humoral tolerance that directly contribute to disease morbidity and mortality. CD154 gene therapy can reverse this immune defect, but attempts to do this pharmacologically have been unsuccessful. The immunemodulatory agent lenalidomide shows clinical activity in CLL, but its mechanism is poorly understood. Here, we demonstrate that lenalidomide induces expression of functional CD154 antigen on CLL IntroductionChronic lymphocytic leukemia (CLL) is the most common adult leukemia, and is characterized by an elevated frequency of infections, secondary malignancy, and autoimmune complications compared with the general population. Current treatment options for CLL are palliative and further exacerbate the immune deficiency seen in this disease. Nonetheless, CLL represents an "immunoresponsive" disease as evidenced by extended disease remission and potential cure with reduced intensity allogeneic stem cell transplantation (reviewed in Gribben 1 ). This suggests that strategies that restore immune function have potential to effectively eliminate CLL.The immune defect in CLL is characterized by both humoral and cellular immune defects. Although detailed studies of normal B cells in CLL patients have not been performed due to the difficulty in isolating these cells, hypogammaglobulinemia is often present at diagnosis and becomes worse with disease progression. A profound cellular immune defect 2-4 is present in CLL with significant alterations in genes involved in differentiation, cytoskeleton formation, vesicle trafficking, and cell death. 4 Coculture of CLL cells with normal T cells produces the same T-cell defects observed in CLL patients, 4 suggesting a direct role of the leukemia cells in contributing to the T cell-dependent cellular immune deficiency. The clinical manifestation of the humoral and cellular immune defects in CLL patients includes hypogammaglobulinemia, 5,6 poor response to both polysaccharide-based 7-9 and proteinbased 10 vaccines, and a high predisposition to infections 11,12 that represents a leading cause of death.To date, attempts to reverse the immune defects in CLL have been limited. Most promising has been adenovirus-delivered CD154 gene therapy that in small numbers of patients reversed cellular and humoral tumor tolerance. CD154 is the surface ligand of CD40 and is expressed on activated T cells, natural killer cells, and dendritic cells, but not normal B cells. Activation of T cells promotes increased surface expression of CD154, thereby promoting both activation and antigen presentation in normal and transformed B cells. Congenital mutations in the CD154 gene promote profound cellular and humoral immune deficiency. Although mutations of the CD154 gene have not been described in CLL, these patients have diminished CD154 expression on T cells after CD3 ligation. 13 Transduction of murine or human CD154 into primary CLL cells ex vivo with adenovirus gene therapy vectors, followed by systemic reintr...

p53 and Notch signaling in chronic lymphocytic leukemia: clues to identifying novel therapeutic strategies

“…76 Treatment of CLL patients with lenalidomide resulted in upregulation of cell-surface CD154 and generation of antibodies to cell-surface Ror1 protein tyrosine kinase. 77 These observations suggested that lenalidomide's mode of action may be partly dependent on reversing the immune dysfunction characteristic of CLL cells. This immunologically based mechanism is probably at least partially independent of functional p53.…”

Identifying CLL antigens for future combinational therapy

“…A striking finding from this study is that CLL patients possess the ability to form anti-LCP1 immunoglobulin (IgG) despite the lack of IgG-based immunity to strong vaccine Ag (tetanus). This suggests that a strong LCP1 autoimmune response is active in spite of the profound immune dysfunction that is a hallmark of CLL (that impacts on T-cells 5 and B-cell effector functions 6 Ag-specific manner. 7 The significant accumulation of CLL cells during disease progression could cause elevated production of exosomes and increase their ability to present Ag (representing chronic "exosomeantigen presentation").…”

“…The immunomodulatory agent (iMiD) lenalidomide has shown impressive clinical trial results in CLL by enhancing both anti-tumor specific granzyme-B 1 T-cells 4 and B-cell immunity (humoral autoimmunity against CLL-membrane Ags, such as receptor tyrosine kinase-like orphan receptor, ROR1). 6 Taken together, targeted KIs that inhibit protumor TME signaling may show synergistic activity with biological therapies (future use of clinical anti-LCP1 mAb) or immunotherapy (lenalidomide or programmed-cell death-1, PD-1 immune checkpoint blocking mAbs). 3 This combinatorial approach could inhibit CLL homing to the TME (blocking BCRsignaling and LCP1 activation), while activating anti-tumor immunity against residual tumor membrane-or exosomeassociated Ags including LCP1.…”

Lymphocyte cytosolic protein 1 is a chronic lymphocytic leukemia membrane-associated antigen critical to niche homing

“…Lenalidomide, an iMiD currently under investigation, was shown to bolster humoral autoimmunity against known CLL-specific membrane antigens. 4 The significance of this autoimmune signature is unknown; however, humoral immunity has previously pinpointed a number of relevant tumor targets including p53, Her2/neu, WT1, MUC1, NY-ESO-1, and, in CLL, ROR1. [5][6][7][8] In terms of CLL therapy, ROR1 is currently under development as both a monoclonal antibody target and chimeric antigen receptor epitope-based therapeutic.…”

“…9 Curiously, proteomic identification of ROR1 was serendipitous with the identification of autoantibody responses against the epitope in CLL patients. 4,8 In CLL, oncogenic signaling derived from multicellular interactions within the specialized niche environment drive the proliferation of an otherwise quiescent leukemic clone. 10 In this respect, receptors, ligands, and other membrane-associated proteins represent potential therapeutic targets, as they are the initiators of intracellular signaling, microenvironment homing, proliferation, and survival.…”