Antibody targeting of Cathepsin S induces antibody-dependent cellular cytotoxicity

<p>Abstract</p> <p>Background</p> <p>Proteolytic enzymes have been implicated in driving tumor progression by means of their cancer cell microenvironment activity where they promote proliferation, differentiation, apoptosis, migration, and invasion. Therapeutic strategies have focused on attenuating their activity using small molecule inhibitors, but the association of proteases with the cell surface during cancer progression opens up the possibility of targeting these using antibody dependent cellular cytotoxicity (ADCC). Cathepsin S is a lysosomal cysteine protease that promotes the growth and invasion of tumour and endothelial cells during cancer progression. Our analysis of colorectal cancer patient biopsies shows that cathepsin S associates with the cell membrane indicating a potential for ADCC targeting.</p> <p>Results</p> <p>Here we report the cell surface characterization of cathepsin S and the development of a humanized antibody (Fsn0503h) with immune effector function and a stable <it>in vivo </it>half-life of 274 hours. Cathepsin S is expressed on the surface of tumor cells representative of colorectal and pancreatic cancer (23%-79% positive expression). Furthermore the binding of Fsn0503h to surface associated cathepsin S results in natural killer (NK) cell targeted tumor killing. In a colorectal cancer model Fsn0503h elicits a 22% cytotoxic effect.</p> <p>Conclusions</p> <p>This data highlights the potential to target cell surface associated enzymes, such as cathepsin S, as therapeutic targets using antibodies capable of elicitingADCC in tumor cells.</p

The humoral immune response of patients receiving radiolabelled murine monoclonal antibodies for the treatment of malignant neoplasia

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Functionalisation of aptamers for the development of effective cancer therapeutics

Aptamers, short oligonucleotide therapeutic, diagnostic and imaging agents, possess great affinity and selectivity for their targets. However, they are limited in terms of application due to their rapid renal clearance and degradation from nucleases in the blood. Thus, it is often necessary to incorporate appropriate modifications for achieving their full potential. Aptamer labelling with appropriate fluorescent moieties or radioisotopes can confer diagnostic and imaging potential, respectively. Various chemical modifications, such as PEGylation, can improve their pharmacokinetic properties and retain aptamers longer in circulation, making them suitable for therapeutic applications. We now present a range of chemical modifications on our tumour-targeting aptamers that have allowed us to develop them as diagnostic or therapeutic agents

Development and characterisation of aptamers as inhibitors of vital pathways in cancer therapy

Aptamers can be described as short oligonucleotides that harbour great potential in their versatile applications, due to their high affinity and specificity for their target of choice. Despite their infancy, aptamers have already emerged at the forefront of clinical research, offering significant contribution as therapeutic agents for a range of diseases. Thus, our research is aimed towards generating aptamer(s) for a specific cancer biomarker that, when blocked, can lead to specific cell kill and thus offer a novel therapeutic potential against cancer

Plasma Membrane Nucleolin Is a Receptor for the Anticancer Aptamer AS1411 in MV4-11 Leukemia Cells

AS1411 is a DNA aptamer that is in phase II clinical trials for relapsed or refractory acute myeloid leukemia and for renal cell carcinoma. AS1411 binds to nucleolin, a protein that is overexpressed in the cytoplasm and on the plasma membrane of some tumor cells compared with normal cells. Studies were performed to determine whether cell surface nucleolin is a receptor for AS1411 in the acute myeloid leukemia cell line MV4-11. Biotinylation of MV4-11 cell surface proteins followed by immunoblotting of the biotinylated proteins showed that full-length (106 kDa) and truncated forms of nucleolin were present on the cell surface. In contrast, K-562 cells, which are 4-fold less sensitive than MV4-11 cells to AS1411, showed no full-length nucleolin and lesser amounts of the truncated forms of nucleolin on the cell surface. Incubation of MV4-11 cells with [32P]AS1411 and immunoprecipitation of the plasma membrane fraction with anti-nucleolin antibody demonstrated the presence of [32P]AS1411-nucleolin complexes. Anti-nucleolin antibody inhibited binding of fluorescein isothiocyanate (FITC)-AS1411 to plasma membrane nucleolin 56 ± 10% SE (P < 0.01) compared with cells incubated with FITC-AS1411 only. Cellular uptake of [32P]AS1411 into MV4-11 cells was blocked by a 20-fold excess of unlabeled AS1411 but not by a 20-fold excess of the biologically inactive oligonucleotide CRO-26. Uptake was approximately 3-fold faster into MV4-11 cells than into K-562 cells. Partial knockdown of plasma membrane and cytosolic nucleolin in MCF-7 cells resulted in a 3-fold decrease in AS1411 uptake. These results provide evidence that plasma membrane nucleolin is a functional receptor for AS1411 in MV4-11 cells

A phase I clinical trial of the selective BTK inhibitor ONO/GS-4059 in relapsed and refractory mature B-cell malignancies.

We report the results of a multi-center Phase I dose escalation study of the selective BTK inhibitor ONO/GS-4059 in 90 patients with relapsed/refractory B-cell malignancies. There were 9 dose escalation cohorts ranging from 20mg once daily (OD) to 600mg OD with twice daily (BID) regimens of 240mg and 300mg BID also investigated. 24/25 (96%) evaluable chronic lymphocytic leukemia (CLL) patients responded to ONO/GS-4059, with a median treatment duration of 80 weeks; 21 CLL patients remain on treatment. Lymph node responses were rapid and associated with a concurrent lymphocytosis in most patients. 11/12 (92%) evaluable patients with Mantle Cell Lymphoma (MCL) responded and 8 remain on study (median treatment duration, 40 weeks). 11/31 (35%) non-germinal center B-cell diffuse large B-cell lymphoma (DLBCL) patients responded but median treatment duration was 12 weeks due to development of progressive disease. ONO/GS-4059 was very well tolerated with 75% of adverse events being CTC-AE V4.0 Grade 1 or Grade 2. Grade 3/4 adverse events were mainly hematological and recovered spontaneously during ongoing therapy. One CLL patient experienced a Grade 3 treatment-related bleeding event (spontaneous muscle hematoma) but no clinically significant diarrhea, cardiac dysrhythmias or arthralgia were observed. No maximal tolerated dose (MTD) was reached in the CLL cohort. In the NHL cohort, 4 patients developed a DLT at higher doses, yielding an MTD of 480mg OD. ONO/GS-4059 has significant activity in relapsed/refractory B-cell malignancies without major drug-related toxicity. The selectivity of ONO/GS-4059 should confer advantages in combination therapies. This clinical trial is registered to www.clinicaltrials.gov as NCT01659255