Surface membrane antigen expression changes induced in vitro by exogenous growth factors in chronic lymphocytic leukemia cells

A tandem CD19/CD20 CAR lentiviral vector drives on-target and off-target antigen modulation in leukemia cell lines

Background

Clinical success with chimeric antigen receptor (CAR)- based immunotherapy for leukemia has been accompanied by the associated finding that antigen-escape variants of the disease are responsible for relapse. To target hematologic malignancies with a chimeric antigen receptor (CAR) that targets two antigens with a single vector, and thus potentially lessen the chance of leukemic escape mutations, a tandem-CAR approach was investigated.

Methods

Antigen binding domains from the FMC63 (anti-CD19) and Leu16 (anti-CD20) antibodies were linked in differing configurations to transmembrane and T cell signaling domains to create tandem-CARs. Expression on the surface of primary human T cells was induced by transduction with a single lentiviral vector (LV) encoding the tandem-CAR. Tandem-CARs were compared to single antigen targeting CARs in vitro and in vivo, and to an admixture of transduced cells expressing each CAR in vivo in immunodeficient (NSG) disease-bearing mice.

Results

Tandem constructs efficient killed the Raji leukemia cell line both in vitro and in vivo. Tandem CARs generated less cytokine than the CD20 CAR, but similar to CD19 CARs, on their own. In co-culture experiments at low effector to target ratios with both single- and tandem- CAR-T cells, a rapid down-modulation of full-length CD19 expression was seen on leukemia targets. There also was a partial down-modulation of CD22, and to a lesser degree, of CD20. Our data also highlight the extreme sensitivity of the NALM-6 cell line to general lymphocyte-mediated cytotoxicity. While single and tandem constructs were effective in vivo in a standard setting, in a high-disease burden setting, the tandem CAR proved both effective and less toxic than an admixture of transduced T cell populations expressing single CARs.

Conclusion

Tandem CARs are equally effective in standard disease models to single antigen specificity CARs, and may be both more effective and less toxic in a higher disease burden setting. This may be due to optimized cell killing with more moderate cytokine production. The rapid co-modulation of CD19, CD20, and CD22 may account for the ability to rapidly evolve escape mutants by selecting for leukemic clones that not require these target antigens for continued expansion.

Electronic supplementary material

The online version of this article (doi:10.1186/s40425-017-0246-1) contains supplementary material, which is available to authorized users.

GIFT4 fusokine converts leukemic B cells into immune helper cells

Background

Chronic lymphocytic leukemia (CLL) remains incurable with standard therapy, and is characterized by excessive expansion of monoclonal abnormal mature B cells and more regulatory immune properties of T cell compartment. Thus, developing novel strategies to enhance immune function merits further investigation as a possible therapy for CLL.

Methods

We generated a fusion cytokine (fusokine) arising from the combination of human GM-CSF and IL-4 (named GIFT4). Primary CLL cells were treated with GIFT4 or GM-CSG and IL-4 in vitro. GIFT4-triggered STAT5 signaling in CLL cells was examined by Western blot. The phenotype and secretome of GIFT4-treated CLL cells (GIFT4-CLL cells), and the immune stimulatory function of GIFT4-CLL cells on autologous T cells were analyzed by flow cytometry and luminex assay.

Results

GIFT4-CLL up-regulated the expression of co-stimulatory molecules CD40, CD80 and CD86 and adhesion molecule CD54. GIFT4-CLL cells secreted IL-1β, IL-6, ICAM-1 and substantial IL-2 relative to unstimulated CLL cells. GIFT4 treatment led to JAK1, JAK2 and JAK3-mediated hyper-phosphorylation of STAT5 in primary CLL cells, which is essential for GIFT4-triggered conversion of CLL cells. GIFT4-CLL cells directly propelled the expansion of autologous IFN-γ-producing CD314⁺ cytotoxic T cells in vitro, and that these could lyse autologous CLL cells. Furthermore, administration of GIFT4 protein promoted the expansion of human T cells in NOD-scid IL2Rγ^null immune deficient mice adoptively pre-transferred with peripheral blood mononuclear cells from subjects with CLL.

Conclusion

GIFT4 has potent capability to converts primary CLL cells into APC-like immune helper cells that initiate a T cell driven anti-CLL immune response.

Nanotechnology applications in hematological malignancies (Review)

A major limitation to current cancer therapies is the development of therapy-related side-effects and dose limiting complications. Moreover, a better understanding of the biology of cancer cells and the mechanisms of resistance to therapy is rapidly developing. The translation of advanced knowledge and discoveries achieved at the molecular level must be supported by advanced diagnostic, therapeutic and delivery technologies to translate these discoveries into useful tools that are essential in achieving progress in the war against cancer. Nanotechnology can play an essential role in this aspect providing a transforming technology that can translate the basic and clinical findings into novel diagnostic, therapeutic and preventive tools useful in different types of cancer. Hematological malignancies represent a specific class of cancer, which attracts special attention in the applications of nanotechnology for cancer diagnosis and treatment. The aim of the present review is to elucidate the emerging applications of nanotechnology in cancer management and describe the potentials of nanotechnology in changing the key fundamental aspects of hematological malignancy diagnosis, treatment and follow-up.

Mitogen induced activation, proliferation and surface antigen expression patterns in unmutated and hypermutated chronic lymphocytic leukemia cells

OBJECTIVES

To determine whether the immunoglobulin V(H) gene mutational status has an effect on the activation, proliferation and surface antigen expression of chronic lymphocytic leukemia (CLL) cells when stimulated in vitro.

METHODS

The proliferation and activation responses of CLL cells were studied in 22-immunoglobulin gene V(H) unmutated (UM-CLL) and 12 hypermutated (M-CLL) CLL cases in 4-day cultures. As the mitogen responses have been previously shown to be diverse in CLL, a case-specific strategy based on optimized mitogen combinations (OMCs) of interleukin-2 (IL-2), 12-O-tetradecanoylphorbol 13-acetate (TPA), Staphylococcus aureus Cowan 1 (SAC), and human recombinant tumor necrosis factor alpha (TNF) was applied in cell stimulation. The expression of 23 surface membrane antigens (CD5, CD11c, CD19, CD20, CD21, CD22, CD23, CD25, CD27, CD38, CD40, CD45, CD45RA, CD45RO, CD79b, CD80, CD95, CD124, CD126, CD130, FMC7, IgD, and IgM) was studied by flow cytometry at days 0 and 4.

RESULTS

The proliferation and activation responses were similar in UM-CLL and M-CLL when OMCs contained IL-2, TPA or TNF. SAC induced faster proliferation in UM-CLL than in M-CLL. OMC stimulation induced preferential down-regulation of growth- promoting cell surface receptors CD5, CD21, and CD124 and preferential up-regulation of growth-inhibiting antigen CD80 in M-CLL.

CONCLUSIONS

Difference in immunophenotypic evolution of UM-CLL and M-CLL can be demonstrated if appropriate matrix signals are provided. The pathways for CD5, CD21, CD124 (IL4R), and CD80 (B7-1) regulation should be further explored in relation with somatic hypermutation and outcome of CLL.

Effect of Serum and Antioxidants on the Immunogenicity of Protein Kinase C-Activated Chronic Lymphocytic Leukemia Cells

Since the intrinsically poor immunogenicity of chronic lymphocytic leukemia (CLL) cells might be a key factor in allowing them to avoid immune control mechanisms, the development of methods to enhance CLL cell immunogenicity might lead to improved disease control. The ability of CLL cells to stimulate T cells was increased significantly by the protein kinase C (PKC) agonist phorbol myristic acetate (PMA). However, under serum-free conditions, PMA-activated CLL cells died within 48 hours. Antioxidants, such as 2-mercaptoethanol (2-ME), or fetal calf serum could prevent the death of these cells but caused them to enter distinct states of differentiation. In the presence of 2-ME, PMA-activated CLL cells extended dendritic-like protrusions and exhibited increased T-cell stimulatory capacity. In the presence of serum, PMA-activated CLL cells developed fewer dendrites, made less IL-10 and more IL-12 p40 mRNA transcripts, and showed an increased capacity to induce IFN-gamma production by T cells. The effects of serum on the promotion of type 1 immune responses by phorbol ester-activated CLL cells were dominant and correlated with activation of the NF-kappaB signaling pathway. Other PKC agonists, such as Bryostatin-1 and a synthetic Bryostatin analog (Picolog), had similar effects on CLL cells. The observation that CLL cells can acquire features of dendritic cells that promote type 1 immunity may find clinical application in immunotherapeutic strategies for this disease.

Effect of IL-2Rβ -binding cytokines on costimulatory properties of chronic lymphocytic leukaemia cells: implications for immunotherapy

Weak immunogenicity of chronic lymphocytic leukaemia (CLL) cells may contribute to disease progression and inhibit the effectiveness of immunotherapies, such as vaccines. Agents that can enhance the antigen presenting capabilities of CLL cells might then help to improve the clinical results of immunotherapies. This study investigated the effects of the common gamma chain-binding cytokines, interleukin (IL)-2 and IL-15, on costimulatory properties of primary CLL cells from 51 patients. IL-2 improved the ability of CLL cells to stimulate T cell proliferation and increased the expression of costimulatory molecules (particularly CD80) in a dose-dependent fashion, especially in CLL cells with weak expression of CD38. CD80 and CD86 induction by IL-2 were positively regulated through the mitogen-activated protein kinase pathway, while CD86 expression was negatively regulated through Janus kinase pathways. However, further activation with protein kinase C agonists was required for IL-2 activated CLL cells to stimulate autologous T cells sufficiently to clear bystander CLL cells from mixed lymphocyte responses. IL-15 had similar effects on the costimulatory properties of CLL cells. These results suggest a role for IL-2, or IL-15, in immunotherapeutic strategies for CLL.

More extensive genetic alterations in unmutated than in hypermutated cases of chronic lymphocytic leukemia

B-cell chronic lymphocytic leukemia (CLL) is not a uniform disease entity; approximately half of the CLL cases have undergone immunoglobulin V(H) gene hypermutation, whereas the other half display unmutated V(H) genes. We investigated genome changes in 12 hypermutated cases (M-CLL) and 22 unmutated cases (UM-CLL) by use of comparative genomic hybridization, G-banding, and multicolor fluorescence in situ hybridization (m-FISH) after optimal mitogen stimulation and FISH analysis of typical CLL aberrations: 11q deletion, 13q deletion, and trisomy 12. Very high frequencies of aberrations were found in both groups: 82% in UM-CLL and 83% in M-CLL. Deletions of 11q and 13q were equally distributed in M-CLL and UM-CLL. However, larger aberrations detectable by CGH, trisomy 12, and complex aberrations were less frequent in M-CLL than in UM-CLL. These observations led to a hypothesis that unmutated and mutated CLL have different biological Backgrounds, given that large and/or complex chromosomal aberrations and hypermutation of the CLL progenitor cells tend to be mutually exclusive.

Surface antigen expression and correlation with variable heavy-chain gene mutation status in chronic lymphocytic leukemia

Recent studies have demonstrated that B-cell chronic lymphocytic leukemia (CLL) consists of two clinical entities with either somatically hypermutated (M-CLL) or unmutated (UM-CLL) immunoglobulin variable heavy-chain (VH) regions. In view of the fact that the cellular biology of these two subsets of disease is currently unexplored, we performed an extensive analysis of the surface antigen expression and correlated this with the VH gene mutation status in a cohort of 32 CLL patients. Using polymerase chain reaction amplification and nucleotide sequencing, the VH genes were shown to be mutated in 10 cases (31%) and unmutated in 22 (69%). The expression of 27 surface membrane antigens in peripheral blood leukemic cells was analyzed by flow cytometry, measuring both the percentage of positive cells as well as the geometric mean fluorescence intensity (GMF). Most of the surface membrane antigens (CD5, CD11c, CD19, CD20, CD21, CD22, CD23, CD25, CD40, CD45, VD79b, CD80, CD95, CD122, CD124, CD126, CD130, CD154, IgM, and IgD) showed a similar expression pattern in both UM-CLL and M-CLL patients. The similarity of M-CLL and UM-CLL, as demonstrated here for the first time with many protein markers, indicates a considerably homogeneous phenotype in both subsets. Furthermore, CD27 was strongly expressed in all cases, which may suggest a memory cell phenotype for both M-CLL and UM-CLL. More positive cells in the UM-CLL group were observed regarding CD38, but CD38 was not a good predictor of VH gene mutation status. Seventy percent of the M-CLL cases, but only 36% of UM-CLL cases, were Ig-lambda+. The most striking differential expression, however, was observed in the two slicing variants of the common leukocyte antigen CD45, namely CD45RO and CD45RA. CD45RO expression was significantly associated with M-CLL, whereas the GMF intensity of CD45RA tended to be associated with UM-CLL. The role of these CD45 splicing variants in the pathogenesis of CLL deserves further investigation.