Receptor-directed therapy of T-cell leukemias and lymphomas

Intratumoral anti-HuD immunotoxin therapy for small cell lung cancer and neuroblastoma

BACKGROUND

Most patients with small cell lung cancer (SCLC) or neuroblastoma (NB) already show clinically detectable metastases at diagnosis and have an extremely poor prognosis even when treated with combined modalities. The HuD-antigen is a neuronal RNA-binding protein that is expressed in 100% of SCLC tumor cells and over 50% of neuroblastoma cells. The correlation between high titers of circulating anti-HuD antibodies in patients and spontaneous tumor remission suggests that the HuD-antigen might be a potential molecular target for immunotherapy.

METHODS

We have constructed a new antibody-toxin compound (called BW-2) by assembling a mouse anti-human-HuD monoclonal antibody onto streptavidin/saporin complexes.

RESULTS

We found that the immunotoxin BW-2 specifically killed HuD-positive human SCLC and NB cancer cells at very low concentrations in vitro. Moreover, intratumoral immunotoxin therapy in a nude mouse model of human SCLC (n = 6) significantly reduced local tumor progression without causing toxicity. When the same intratumoral immunotoxin protocol was applied to an immunocompetent A/J mouse model of NB, significant inhibition of local tumor growth was also observed. In neuroblastoma allografted A/J mice (n = 5) treated twice with intratumoral immunotoxin, significant tumor regression occurred in over 80% of the animals and their duration of tumor response was significantly prolonged.

CONCLUSIONS

Our study suggests that anti-HuD based immunotoxin therapy may prove to be an effective alternative treatment for patients with SCLC and NB.

Characteristics of CARMA1-BCL10-MALT1-A20-NF-κB expression in T cell-acute lymphocytic leukemia

Background

Knowledge of the oncogenic signaling pathways of T-cell acute lymphoblastic leukemia (T-ALL) remains limited. Constitutive aberrant activation of the nuclear factor kappa B (NF-κB) signaling pathway has been detected in various lymphoid malignancies and plays a key role in the development of these carcinomas. The zinc finger-containing protein, A20, is a central regulator of multiple NF-κB-activating signaling cascades. A20 is frequently inactivated by deletions and/or mutations in several B-and T-cell lymphoma subtypes. However, few A20 mutations and polymorphisms have been reported in T-ALL. Thus, it is of interest to analyze the expression characteristics of A20 and its regulating factors, including upstream regulators and the CBM complex, which includes CARMA1, BCL10, and MALT1.

Methods

The expression levels of CARMA1, BCL10, MALT1, A20, and NF-κB were detected in peripheral blood mononuclear cells (PBMCs) from 21 patients with newly diagnosed T-ALL using real-time PCR, and correlations between the aberrant expression of these genes in T-ALL was analyzed. Sixteen healthy individuals, including 10 males and 6 females, served as controls.

Results

Significantly lower A20 expression was found in T-ALL patients (median: 4.853) compared with healthy individuals (median: 8.748; P = 0.017), and significantly increased expression levels of CARMA1 (median: 2.916; P = 0.034), BCL10 (median: 0.285; P = 0.033), and MALT1 (median: 1.201; P = 0.010) were found in T-ALL compared with the healthy individuals (median: 1.379, 0.169, and 0.677, respectively). In contrast, overexpression of NF-κB (median: 0.714) was found in T-ALL compared with healthy individuals (median: 0.335; P = 0.001). A negative correlation between the MALT1 and A20 expression levels and a positive correlation between CARMA1 and BCL10 were found in T-ALL and healthy individuals. However, no negative correlation was found between A20 and NF-κB and the MALT1 and NF-κB expression level in the T-ALL group.

Conclusions

We characterized the expression of the CARMA-BCL10-MALT1-A20-NF-κB pathway genes in T-ALL. Overexpression of CARMA-BCL10-MALT in T-ALL may contribute to the constitutive cleavage and inactivation of A20, which enhances NF-κB signaling and may be related to T-ALL pathogenesis.

Markedly additive antitumor activity with the combination of a selective survivin suppressant YM155 and alemtuzumab in adult T-cell leukemia

Adult T-cell leukemia (ATL) is an aggressive malignancy of CD4(+)CD25(+) lymphocytes caused by human T-cell lymphotropic virus type 1. Currently, there is no accepted curative therapy for ATL. In gene expression profiling, the antiapoptotic protein survivin (BIRC5) demonstrated a striking increase in ATL, and its expression was increased in patient ATL cells resistant to the anti-CD52 monoclonal antibody alemtuzumab (Campath-1H). In this study, we investigated the antitumor activity of a small-molecule survivin suppressant YM155 alone and in combination with alemtuzumab in a murine model of human ATL (MET-1). Both YM155 alone and its combination with alemtuzumab demonstrated therapeutic efficacy by lowering serum soluble IL-2Rα (sIL-2Rα) levels (P < .001) and prolonged the survival of tumor-bearing mice (P < .0001). Moreover, the combination of YM155 with alemtuzumab demonstrated markedly additive antitumor activity by significantly lowering serum sIL-2Rα levels and improving the survival of leukemia-bearing mice compared with monotherapy with either YM155 (P < .001) or alemtuzumab (P < .05). More significantly, all mice that received the combination therapy survived and were tumor free >6 months after treatment. Our data support a clinical trial of the combination of YM155 with alemtuzumab in ATL. This trial was registered at www.clinicaltrials.gov as #NCT00061048.

Mutations increased overexpression of Notch1 in T-cell acute lymphoblastic leukemia

Background

The Notch signaling pathway is crucial in T-cell development, Notch1 mutations are frequently present in T-cell acute lymphoblastic leukemia (T-ALL). To investigate the feature of Notch1 mutation and its corresponding expression level in Chinese patients with T-ALL, detection of mutation and the expression level of Notch1 gene was preformed using RT-PCR, sequencing and real-time PCR respectively.

Results

Two Notch1 point mutations (V1578E and L1593P) located on HD-N domain were identified in three cases out of 13 T-ALL patients. The mutation on 4733 position (V1578E) found in two cases was a novel mutation. The overexpression of Notch1 was detected in all samples with T-ALL, moreover, significantly higher expression of Notch1 was detected in the T-ALL with Notch1 mutation group compared with T-ALL with WT Notch1 group (p = 0.0192).

Conclusions

Higher expression of Notch1 was associated with Notch1 mutation, more novel mutation of this gene might be identified in different populations and its contribution to the molecular pathogenesis of T-ALL is needed further research.

Analysis of the expression pattern of the BCL11B gene and its relatives in patients with T-cell acute lymphoblastic leukemia

Background

In a human T-cell acute lymphoblastic leukemia (T-ALL) cell line (Molt-4), siRNA-mediated suppression of BCL11B expression was shown to inhibit proliferation and induce apoptosis, functions which may be related to genes involved in apoptosis (such as TNFSF10 and BCL2L1) and TGF-β pathways (such as SPP1and CREBBP).

Methods

The expression levels of the above mentioned genes and their correlation with the BCL11B gene were analyzed in patients with T-ALL using the TaqMan and SYBR Green I real-time polymerase chain reaction technique.

Results

Expression levels of BCL11B, BCL2L1, and CREBBP mRNA in T-ALL patients were significantly higher than those from healthy controls (P <0.05). In T-ALL patients, the BCL11B expression level was negatively correlated with the BCL2L1 expression level (r_s = -0.700; P <0.05), and positively correlated with the SPP1 expression level (r_s = 0.683; P <0.05). In healthy controls, the BCL11B expression level did not correlate with the TNFSF10, BCL2L1, SPP1, or CREBBP expression levels.

Conclusions

Over-expression of BCL11B might play a role in anti-apoptosis in T-ALL cells through up-regulation of its downstream genes BCL2L1 and CREBBP.

Antibody-based therapy of leukaemia

Over the past decade, monoclonal antibodies have dramatically impacted the treatment of haematological malignancies, as evidenced by the effect of rituximab on the response rate and survival of patients with follicular and diffuse large B cell non-Hodgkin's lymphoma. Currently, only two monoclonal antibodies - the anti-CD33 immunotoxin gemtuzumab ozogamicin and the CD52-directed antibody alemtuzumab - are approved for treatment of relapsed acute myeloid leukaemia in older patients and B cell chronic lymphocytic leukaemia, respectively. Although not approved for such treatment, alemtuzumab is also active against T cell prolymphocytic leukaemia, cutaneous T cell lymphoma and Sézary syndrome, and adult T cell leukaemia and lymphoma. In addition, rituximab has demonstrated activity against B cell chronic lymphocytic and hairy cell leukaemia. Monoclonal antibodies targeting CD4, CD19, CD20, CD22, CD23, CD25, CD45, CD66 and CD122 are now being studied in the clinic for the treatment of leukaemia. Here, we discuss how these new antibodies have been engineered to reduce immunogenicity and improve antibody targeting and binding. Improved interactions with Fc receptors on immune effector cells can enhance destruction of target cells through antibody-dependent cellular cytotoxicity and complement-mediated cell lysis. The antibodies can also be armed with cellular toxins or radionuclides to enhance the destruction of leukaemia cells.