Matthew Robinson, PhD
Office Phone: 215-728-3141
The work in my laboratory is focused on developing molecularly targeted therapeutics and diagnostics that are designed to exploit the signal transduction networks that drive cancer formation and progression. This is accomplished through use of single-chain Fv antibodies. Single-chain Fv fragments (scFv) are engineered antibodies comprised solely of the antigen binding domains (variable heavy and variable light chains) of IgGs fused into a single polypeptide by the addition of a short, flexible, linker sequence. These molecules possess the antigen binding specificity of intact IgGs and have been used to create human scFv phage libraries that can be used to isolate scFv specific for targets of interest. An additional focus of the lab is the development of immune modulatory antibodies with the goal of promoting anti-tumor effects and stimulating memory immune responses.
1. Preclinical Development of Bispecific Single-chain Fv Antibody Molecules (bs-scFv) That Co-target ErbB Family Members for the Treatment of CancerA Novel, Bispecific Antibody's path from the Lab to clinic This content requires the Adobe Flash Player.
Video: Learn more about the origins of bispecific antibody
research at Fox Chase with Dr. Gregory Adams
and Dr. Matthew Robinson (6 minutes).
The epidermal growth factor (EGF) receptor family of receptor-tyrosine kinases (RTKs) is comprised of four members: EGFR/ErbB1, HER2/ErbB2, HER3/ErbB3, and HER4/ErbB4. ErbB signaling promotes divergent cellular outcomes depending upon cellular context, specific ligand, and constituents of the activated ErbB dimer. Inappropriate activation of signaling pathways downstream of the ErbB family of receptors has been causally linked to the formation and progression of a number of cancers, making them important targets for development of molecularly targeted therapies. We have developed and characterized a bs-scFv engineered antibody, designated ALM,which binds specifically to the ErbB2/ErbB3 heterodimer. This growth factor receptor pair is the most potent of the ErbB heterodimers with respect to activation of downstream signaling pathways in cancer cells. ALM was developed based on two hypotheses:
1. A bs-scFv targeting the ErbB2/ErbB3 heterodimer would be able to disrupt the pro-survival signaling pathways downstream of this clinically relevant pair of receptors.
2. Co-targeting two tumor associated antigens would increase targeting selectivity over antibodies that target a single antigen. In a recent manuscript we have demonstrated that ALM, when assayed in vitro, selectively binds to ErbB2-positive/ErbB3-positive cells as compared to cells that express only one of the receptors or low levels of both ErbB2 and ErbB3. This specific targeting translates into selective tumor retention of ALM in vivo. Treatment of ErbB2-positive/ErbB3-positive breast cancer cells with ALM inhibits cell growth in culture.Top
A. Use of ALM as a therapeuticIrina Shchaveleva
ALM is a first generation bs-scFv antibody that exhibits promising targeting selectivity and substantial intrinsic anti-tumor cell activity in vitro. Studies are currently underway to evaluate the in vivo therapeutic efficacy of ALM in a mouse model of breast cancer both alone and in combination with chemotherapy. However, we hypothesize that modifications can be made to alter the pharmacokinetics and antigen binding affinity of this molecule that will increase overall tumor retention without decreasing tumor targeting selectivity and therefore enhance the therapeutic potential of the molecule in vivo. Efforts toward this end are ongoing. In addition, we believe that the rapid targeting and systemic clearance of ALM make it suitable for use as an immunodrug conjugate. Future work will also test the hypothesis that coupling the highly selective tumor targeting of ALM with the anti-cancer activity of chemotherapy agents/small molecule toxins by creating immunodrug conjugates will widen the therapeutic window associated with free drug.
We are also performing high throughput siRNA modifier screens to identify genes that alter response of breast cancer cell lines to ALM. Once “hits” have been validated, it is hypothesized that these genes will be instrumental in predicting patient response to ALM-based therapy.Top
B. Resistance to EGFR-targeted therapies in head and neck cancer
Overexpression of the EGFR receptor in squamous cell carcinoma of the head and neck (HNSCC) is correlated with aggressive disease and poor patient outcome. Despite this correlation, EGFR-targeted therapies [e.g. monoclonal antibody cetuximab and small-molecule tyrosine kinase inhibitors (TKIs) erlotinib and gefitinib] have relatively modest clinical efficacy. The ability of EGFR to activate downstream effector pathways, in particular the PI3K-AKT pathway through heterodimerization with ErbB3 is felt to contribute to tumor aggressiveness. In addition, ErbB3 is becoming increasingly recognized as playing a role in the development of resistance to TKIs in a number of cancers. We have hypothesized that bs-scFvs targeting appropriate EGFR family members would be efficacious in the setting of HNSCC and could potentially reverse acquired resistance to the current TKIs. To accomplish this work I will take advantage of ALM, as well as a panel of scFvs that we have against all four member of the EGFR family of RTKs to create antibody-based agents targeting ErbB3 and EGFR.Top
2. Effect of Antigen-related Variables on Performance of Antibody-based PET Radiotracers
Proper assessment of both the etiology/pathophysiology and the progression of disease are essential to the management of cancer. Diagnostic imaging is invaluable to gaining this information. At present, the majority of medical imaging is performed with anatomy-based modalities such as computed tomography (CT). Positron emission tomography with the radiotracer 18F-fluoro-2-deoxy-D-glucose (FDG-PET) images metabolic activity as a surrogate for malignant activity and represents an effective, complimentary, alternative to anatomy-based imaging for many types of cancer. Recent efforts have been made to expand the utility of PET by developing antibody-based radiotracers. It is postulated that the specificity afforded by antibody targeting should both improve tumor detection as compared to FDG-PET and provide phenotypic information related to primary and metastatic lesions that will guide therapy decisions.
To date, development of antibody-based radiotracers for PET has focused almost exclusively on determining the appropriate molecular structure of the antibody molecule necessary to provide good tumor uptake and retention combined with rapid systemic clearance. While very important, this work has been performed in the absence of an understanding of how variables such as the density of antigen molecules on the surface of tumor cells or the levels of shed antigen in circulation will affect radiotracer performance. Additionally, the human tumor xenografts models used for preclinical evaluation provide an unrealistic tumor-restricted expression of the target antigen due to fact that the tumor xenografts are the sole source of antigen expression.
A goal of our research is to evaluate how each of these variables impact on the performance of antibody-based tracers. To do this we are using transgenic mouse lines that express distinct, clinically relevant, human antigens on normal tissues and shed those antigens into the blood stream similarly to patients. These experiments allow us to evaluate antibody-based imaging probes in a more realistic setting of normal tissue expression and develop protocols to overcome the hypothesized deleterious effects. One such approach that is tied in with other ongoing work is to develop bs-scFvs as diagnostic agents. The results of this work will support a collaborative project that is focused on translating a novel scFv-based molecule, the anti-ErbB2 C6.5 diabody, into Phase 0 clinical imaging trials.Top
3. Nanotechnology-based Biosensors for the Detection of Prostate Cancer
Prostate cancer (CaP) is the most commonly diagnosed cancer and second leading cause of cancer deaths among American men. Detection of early-stage, localized, disease is critical for successful treatment outcomes with long term disease-free survival being seen in 60-90% of patients. This is in direct contrast to locally advanced and metastatic disease, where cure is unlikely. At present, digital rectal exams (DRE) and screening for serum levels of the biomarker prostate specific antigen (PSA) are the “gold-standard” for detection of CaP. It is hypothesized that identification of new biomarkers, molecular or tissue-based signatures of disease that can be detected through specialized assays, will increase our ability to detect CaP at earlier stages. Recently it has become clear that nanoscale devices can be functionalized with antibody molecules to create biosensor platforms for the detection of cancer biomarkers. It is hypothesized that the small scale of the devices, in combination with the selectivity imparted by antibodies, will result in highly sensitive biosensor platforms. In collaboration with colleagues at the University of Pennsylvania we are working to develop two nanotechnology devices, single-wall carbon nanotubes (swCNs) and nanomechanical resonators, as platforms for label-free detection of cancer biomarkers.
Efforts in my laboratory are focused on the isolation and optimization of antibodies specific for our proof-of-concept CaP biomarkers. Detection via the two platforms is based on different physical properties. We are using antibody-engineering techniques to tailor the antibody structures for each device and evaluating devices for sensitivity and specificity.Top