Novel antibody therapy in acute lymphoblastic leukemia

Challenges and Opportunities for Childhood Cancer Drug Development

Cancer in children is rare with approximately 15,700 new cases diagnosed in the United States annually. Through use of multimodality therapy (surgery, radiation therapy, and aggressive chemotherapy), 70% of patients will be "cured" of their disease, and 5-year event-free survival exceeds 80%. However, for patients surviving their malignancy, therapy-related long-term adverse effects are severe, with an estimated 50% having chronic life-threatening toxicities related to therapy in their fourth or fifth decade of life. While overall intensive therapy with cytotoxic agents continues to reduce cancer-related mortality, new understanding of the molecular etiology of many childhood cancers offers an opportunity to redirect efforts to develop effective, less genotoxic therapeutic options, including agents that target oncogenic drivers directly, and the potential for use of agents that target the tumor microenvironment and immune-directed therapies. However, for many high-risk cancers, significant challenges remain.

HAP1 loss confers l-asparaginase resistance in ALL by downregulating the calpain-1-Bid-caspase-3/12 pathway

l-Asparaginase (l-ASNase) is a strategic component of treatment protocols for acute lymphoblastic leukemia (ALL). It causes asparagine deficit, resulting in protein synthesis inhibition and subsequent leukemic cell death and ALL remission. However, patients often relapse because of the development of resistance, but the underlying mechanism of ALL cell resistance to l-asparaginase remains unknown. Through unbiased genome-wide RNA interference screening, we identified huntingtin associated protein 1 (HAP1) as an ALL biomarker for l-asparaginase resistance. Knocking down HAP1 induces l-asparaginase resistance. HAP1 interacts with huntingtin and the intracellular Ca²⁺ channel, inositol 1,4,5-triphosphate receptor to form a ternary complex that mediates endoplasmic reticulum (ER) Ca²⁺ release upon stimulation with inositol 1,4,5-triphosphate₃ Loss of HAP1 prevents the formation of the ternary complex and thus l-asparaginase-mediated ER Ca²⁺ release. HAP1 loss also inhibits external Ca²⁺ entry, blocking an excessive rise in [Ca²⁺]_i, and reduces activation of the Ca²⁺-dependent calpain-1, Bid, and caspase-3 and caspase-12, leading to reduced number of apoptotic cells. These findings indicate that HAP1 loss prevents l-asparaginase-induced apoptosis through downregulation of the Ca²⁺-mediated calpain-1-Bid-caspase-3/12 apoptotic pathway. Treatment with BAPTA-AM [1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis(acetoxymethyl ester)] reverses the l-asparaginase apoptotic effect in control cells, supporting a link between l-asparaginase-induced [Ca²⁺]_i increase and apoptotic cell death. Consistent with these findings, ALL patient leukemic cells with lower HAP1 levels showed resistance to l-asparaginase, indicating the clinical relevance of HAP1 loss in the development of l-asparaginase resistance, and pointing to HAP1 as a functional l-asparaginase resistance biomarker that may be used for the design of effective treatment of l-asparaginase-resistant ALL.

Treatment of Relapsed/Refractory Acute Lymphoblastic Leukemia in Adults

Patients with relapsed and refractory acute lymphoblastic leukemia (ALL) have a dismal prognosis with less than 10 % of patients surviving 5 years. Most such patients cannot be rescued with currently available therapies, whatever the initial treatment they receive. Therefore, there is an urgent need for novel treatment options. Fortunately, over the past several years, an improved understanding of the biology of the disease has allowed the identification of rational molecular targets for therapeutic endeavors and the emergence of novel therapies has sparked great interest. This review will discuss the current treatment landscape for adult patients with relapsed and/or refractory ALL.

Host Immune Responses in HIV-1 Infection: The Emerging Pathogenic Role of Siglecs and Their Clinical Correlates

A better understanding of the mechanisms employed by HIV-1 to escape immune responses still represents one of the major tasks required for the development of novel therapeutic approaches targeting a disease still lacking a definitive cure. Host innate immune responses against HIV-1 are key in the early phases of the infection as they could prevent the development and the establishment of two hallmarks of the infection: chronic inflammation and viral reservoirs. Sialic acid-binding immunoglobulin-like lectins (Siglecs) belong to a family of transmembrane proteins able to dampen host immune responses and set appropriate immune activation thresholds upon ligation with their natural ligands, the sialylated carbohydrates. This immune-modulatory function is also targeted by many pathogens that have evolved to express sialic acids on their surface in order to escape host immune responses. HIV-1 envelope glycoprotein 120 (gp120) is extensively covered by carbohydrates playing active roles in life cycle of the virus. Indeed, besides forming a protecting shield from antibody recognition, this coat of N-linked glycans interferes with the folding of viral glycoproteins and enhances virus infectivity. In particular, the sialic acid residues present on gp120 can bind Siglec-7 on natural killer and monocytes/macrophages and Siglec-1 on monocytes/macrophages and dendritic cells. The interactions between these two members of the Siglec family and the sialylated glycans present on HIV-1 envelope either induce or increase HIV-1 entry in conventional and unconventional target cells, thus contributing to viral dissemination and disease progression. In this review, we address the impact of Siglecs in the pathogenesis of HIV-1 infection and discuss how they could be employed as clinic and therapeutic targets.

Muramyl dipeptide and anti-CD10 monoclonal antibody immunoconjugate enhances anti-leukemia immunity of T lymphocytes

It is necessary to completely eliminate minimal residual disease (MRD) to cure acute leukemia. Monoclonal antibodies (MAb) have been shown to be effective to eliminate MRD. In this study we aimed to investigate the effect of anti-CD10 MAb conjugated to muramyl dipeptide immunoconjugate (MDP-Ab) on the function of lymphocytes and activated lymphocytes using leukemia xenografts in nude mice as a model. Peripheral blood mononuclear cells were isolated from children with acute lymphoblastic leukemia and induced into dendritic cells (DCs) and lymphocytes. Cytotoxic activity of lymphocytes was detected by LDH release assay. Leukemia xenografts in nude mice were established to assess tumor growth. We found that the killing rate was significantly higher in MDP-Ab group, LPS group and MDP-Ab+LPS group than in control group, and was the highest in MDP-Ab+LPS group. Tumor-bearing mice in MDP-Ab group showed obvious coagulation necrosis. In conclusion, our data suggest that MDP-Ab could effectively prime DCs to improve the anti-tumor immunity of T lymphocytes and inhibit the tumor growth. MDP-Ab may be used as suitable candidate for eliminating residual leukemia cells to prevent relapse.

Recombinant antibody production evolves into multiple options aimed at yielding reagents suitable for application-specific needs

BACKGROUND

Antibodies have been a pillar of basic research, while their relevance in clinical diagnostics and therapy is constantly growing. Consequently, the production of both conventional and fragment antibodies constantly faces more demanding challenges for the improvement of their quantity and quality. The answer to such an increasing need has been the development of a wide array of formats and alternative production platforms. This review offers a critical comparison and evaluation of the different options to help the researchers interested in expressing recombinant antibodies in their choice.

RESULTS

Rather than the compilation of an exhaustive list of the recent publications in the field, this review intendeds to analyze the development of the most innovative or fast-growing strategies. These have been illustrated with some significant examples and, when possible, compared with the existing alternatives. Space has also been given to those solutions that might represent interesting opportunities or that investigate critical aspects of the production optimization but for which the available data as yet do not allow for a definitive judgment.

CONCLUSIONS

The take-home message is that there is a clear process of progressive diversification concerning the antibody expression platforms and an effort to yield directly application-adapted immune-reagents rather than generic naked antibodies that need further in vitro modification steps before becoming usable.

Adolescent and young adult patients with cancer: a milieu of unique features

Adolescent and young adult (AYA) patients with cancer are a unique category of patients who, depending on age at time of diagnosis, might receive treatment from oncologists specializing either in the treatment of children or adults. In the USA, AYA oncology generally encompasses patients 15-39 years of age. AYA patients with cancer typically present with diseases that span the spectrum from 'paediatric' cancers (such as acute lymphoblastic leukaemia [ALL] and brain tumours) to 'adult' tumours (such as breast cancer and melanoma), as well as cancers that are largely unique to their age group (such as testicular cancer and bone tumours). Research indicates that outcomes of AYA patients with cancer are influenced not only by the treatment provided, but also by factors related to 'host' biology. In addition to the potential biological and cancer-specific differences between AYAs and other patients with cancer, AYA patients also often have disparate access to clinical trials and suffer from a lack of age-appropriate psychosocial support services and health services, which might influence survival as well as overall quality of life. In this Review, these issues are discussed, with a focus on two types of AYA cancer--ALL and melanoma--highlighting findings arising from the use of emerging technologies, such as whole-genome sequencing.