Targeting MT1-MMP as an ImmunoPET-Based Strategy for Imaging Gliomas

Abstract

BackgroundA critical challenge in the management of Glioblastoma Multiforme (GBM) tumors is the accurate diagnosis and assessment of tumor progression in a noninvasive manner. We have identified Membrane-type 1 matrix metalloproteinase (MT1-MMP) as an attractive biomarker for GBM imaging since this protein is actively involved in tumor growth and progression, correlates with tumor grade and is closely associated with poor prognosis in GBM patients. Here, we report the development of an immunoPET tracer for effective detection of MT1-MMP in GBM models.MethodsAn anti-human MT1-MMP monoclonal antibody (mAb), LEM2/15, was conjugated to p-isothiocyanatobenzyl-desferrioxamine (DFO-NCS) for 89Zr labeling. Biodistribution and PET imaging studies were performed in xenograft mice bearing human GBM cells (U251) expressing MT1-MMP and non-expressing breast carcinoma cells (MCF-7) as negative control. Two orthotopic brain GBM models, patient-derived neurospheres (TS543) and U251 cells, with different degrees of blood-brain barrier (BBB) disruption were also used for PET imaging experiments.Results89Zr labeling of DFO-LEM2/15 was achieved with high yield (>90%) and specific activity (78.5 MBq/mg). Biodistribution experiments indicated that 89Zr-DFO-LEM2/15 showed excellent potential as a radiotracer for detection of MT1-MMP positive GBM tumors. PET imaging also indicated a specific and prominent 89Zr-DFO-LEM2/15 uptake in MT1-MMP+ U251 GBM tumors compared to MT1-MMP- MCF-7 breast tumors. Results obtained in orthotopic brain GBM models revealed a high dependence of a disrupted BBB for tracer penetrance into tumors. 89Zr-DFO-LEM2/15 showed much higher accumulation in TS543 tumors with a highly disrupted BBB than in U251 orthotopic model in which the BBB permeability was only partially increased. Histological analysis confirmed the specificity of the immunoconjugate in all GBM models.ConclusionA new anti MT1-MMP-mAb tracer, 89Zr-DFO-LEM2/15, was synthesized efficiently. In vivo validation showed high-specific-contrast imaging of MT1-MMP positive GBM tumors and provided strong evidence for utility of MT1-MMP-targeted immunoPET as an alternate to nonspecific imaging of GBM.

Metalloproteinases and their roles in human cancer

“…Positron emission tomography detection of orthotopic glioblastoma tumors was reported using an MMP‐14 monoclonal antibody conjugated to zirconium‐89 ( 89 Zr). However, the efficacy of this imaging depended on the disruption in the permeability of the tumor vasculature that would allow for the penetrance of the tracer to the brain (de Lucas et al, ). Radiolabeling of MMP inhibitors has also been reported as another potential approach that would allow for simultaneous imaging and targeting of MMPs (Breyholz et al, ).…”

MT1-MMP deficiency leads to defective ependymal cell maturation, impaired ciliogenesis, and hydrocephalus

“…MT1-MMP-deficient mice exhibit dwarfism, skeletal abnormalities, and soft tissue defects and die before adulthood, suggesting a crucial function of MT1-MMP in development and postnatal growth (16)(17)(18)(19)(20)(21). Recent studies proposed that MT1-MMP may be a potential therapeutic target in glioblastoma (22)(23)(24). However, the role of MT1-MMP in the developing brain remains largely unexplored.…”

MT1-MMP as a PET Imaging Biomarker for Pancreas Cancer Management

“…Initial studies on 89 Zr-labelled LEM2/15, an antihuman MT1-MMP mAb, as an immunoPET probe for glioblastoma in xenograft mice were previously reported by our group [ 19 ]. Now in this study, the use of 89 Zr-DFO-LEM2/15 was validated as an immunoPET probe in CAPAN-2 cell line as well as in patient-derived pancreatic ductal adenocarcinoma xenografts.…”

“…When designing these types of PET probes, careful consideration should be given beforehand to the values of the half-life of the biomolecule and of the physical life of the positron-emitting radionuclide that are to be linked. Thus, PET radionuclides with longer half-lives, such as 89 Zr (78.4 hours), are ideally suited for conjugation with intact antibodies (which remain in the blood for long) while smaller peptides (which have shorter clearance times) must be labelled with PET isotopes featuring short or intermediate half-lives such as 68 Ga. We have recently developed an 89 Zr-labelled LEM15/2-based probe for the effective monitoring of MT1-MMP by PET in preclinical GBM mouse models [ 19 ]. Here, we have tested and assessed this probe in pancreatic cancer mouse models, together with a 68 Ga-labelled MT1-AF7p peptide.…”