PRECISION: the Belgian molecular profiling program of metastatic cancer for clinical decision and treatment assignment

PRECISION is an initiative from the Belgian Society of Medical Oncology (BSMO) in collaboration with several stakeholders, encompassing four programs that aim to boost genomic and clinical knowledge with the ultimate goal to offer patients with metastatic solid tumors molecularly guided treatments. The PRECISION 1 study has led to the creation of a clinico-genomic database. The Belgian Approach for Local Laboratory Extensive Tumor Testing (BALLETT) and GeNeo studies will increase the number of patients with advanced cancer that have comprehensive genotyping of their cancer. The PRECISION 2 project consists of investigator-initiated phase II studies aiming to provide access to a targeted drug for patients whose tumors harbor actionable mutations in case the matched drug is not available through reimbursement or clinical trials in Belgium.

Perspectives on the integration of Immuno-Oncology Biomarkers and drugs in a Health Care setting

Immunotherapies, specifically checkpoint inhibitors, are becoming an important component in cancer care with the most application now in melanoma and lung cancer patients. Some drawbacks that converge with this new evolution are the rather low response rates to these drugs and their high cost with a significant economic impact on the health care system. These major challenges can likely be circumvented by implementing a "personalized immuno-oncology" approach to accomplish a selection of optimal responders based on biomarkers. In this paper we first discuss the legal framework for the development of valuable in vitro diagnostics. Based on a case study in lung cancer, the clinical validity and utility requirements of predictive immuno-oncology biomarkers is highlighted and an overview is given on the evolution towards multiplex or omics-based assays together with its challenges and pitfalls. Finally, some initiatives between the public and private sector are pinpointed to sustain the future access to innovative medicines in cancer therapy at a reasonable cost.

Antitumour and antiangiogenic effects of Aplidin in the 5TMM syngeneic models of multiple myeloma

Aplidin® is an antitumour drug, currently undergoing phase II evaluation in different haematological and solid tumours. In this study, we analysed the antimyeloma effects of Aplidin in the syngeneic 5T33MM model, which is representable for the human disease. In vitro, Aplidin inhibited 5T33MMvv DNA synthesis with an IC₅₀ of 3.87 nM. On cell-cycle progression, the drug induced an arrest in transition from G0/G1 to S phase, while Western blot showed a decreased cyclin D1 and CDK4 expression. Furthermore, Aplidin induced apoptosis by lowering the mitochondrial membrane potential, by inducing cytochrome c release and by activating caspase-9 and caspase-3. For the in vivo experiment, 5T33MM-injected C57Bl/KaLwRij mice were intraperitoneally treated with vehicle or Aplidin (90 μg kg⁻¹ daily). Chronic treatment with Aplidin was well tolerated and reduced serum paraprotein concentration by 42% (P<0.001), while BM invasion with myeloma cells was decreased by 35% (P<0.001). Aplidin also reduced the myeloma-associated angiogenesis to basal values. This antiangiogenic effect was confirmed in vitro and explained by inhibition of endothelial cell proliferation and vessel formation. These data indicate that Aplidin is well tolerated in vivo and its antitumour and antiangiogenic effects support the use of the drug in multiple myeloma.

Endothelial cell-driven regulation of CD9 or motility-related protein-1 expression in multiple myeloma cells within the murine 5T33MM model and myeloma patients

The cell surface expression of CD9, a glycoprotein of the tetraspanin family influencing several processes including cell motility and metastasis, inversely correlates with progression in several solid tumors. In the present work, we studied the expression and role of CD9 in multiple myeloma (MM) biology using the 5T33MM mouse model. The 5T33MMvitro cells were found to be CD9 negative. Injection of these cells in mice caused upregulation of CD9 expression, while reculturing them resulted in downregulation of CD9. Coculturing of CD9-negative 5T33MMvitro cells with BM endothelial cells (BMECs) resulted in a partial retrieval of CD9. Laser microdissection followed by real-time polymerase chain reaction and immunohistochemistry performed on bone sections of 5T33MMvivo diseased mice demonstrated strong local expression of CD9 on MM cells in contact with BMEC compared to MM cells further away. These findings were also confirmed by immunohistochemistry in MM patients. Neutralizing anti-CD9 antibodies inhibited transendothelial invasion of CD9-expressing human MM5.1 and murine 5T33MMvivo cells. In conclusion, we provide evidence that CD9 expression by the MM cells is upregulated in vivo by close interaction of the cells with BMEC and that CD9 is involved in transendothelial invasion, thus possibly mediating homing and/or spreading of the MM cells.

Targeting an MMP-9-activated prodrug to multiple myeloma-diseased bone marrow: a proof of principle in the 5T33MM mouse model

Multiple myeloma (MM) is an incurable B-cell cancer characterised by the monoclonal proliferation of tumour cells in the bone marrow (BM). It has been described that matrix metalloproteinases (MMPs) and especially MMP-9 is secreted by MM cells. In this study, we investigated the possibility to exploit MMP-9 activity to activate prodrugs and to target MM cells as a new tumour-specific therapy. Cleavage of the prodrug EV1-FITC by MMP-9 resulted in release of fluorescence which can be used as a measure of prodrug activation. The 5T33MM mouse model was used in this proof-of-principle study. The prodrug was activated in a higher amount by addition to MMP-9-producing 5T33MMvv cells, homogenates from tumour-bearing organs (BM, spleen) and isolated 5T33MM-diseased BM and spleen cells compared to non-MMP-9-producing 5T33MMvt cells and homogenates/cells from non-tumour-bearing organs/mice, as measured by fluorescence release. This fluorescence release could be inhibited by the MMP-2/MMP-9-specific inhibitor, CTT. Activation of the prodrug in the 5T33MM spleen and BM homogenates was confirmed by chromatography. EV1-fluorescein isothiocyanate injection into 5T33MM-diseased animals resulted in a higher fluorescence release by the isolated BM and spleen cells compared to injection into healthy animals. In conclusion, MMP-9 activity can be used to activate prodrugs that target MM.

Specific roles for the PI3K and the MEK-ERK pathway in IGF-1-stimulated chemotaxis, VEGF secretion and proliferation of multiple myeloma cells: study in the 5T33MM model

Insulin-like growth factor-1 (IGF-1) has been described as an important factor in proliferation, cell survival and migration of multiple myeloma (MM) cells. Angiogenesis correlates with development and prognosis of the MM disease. Vascular endothelial growth factor (VEGF) is one of the prominent factors involved in this process. The different functions of IGF-1 were investigated in the 5TMM mouse model with emphasis on proliferation, migration and VEGF secretion, and the signalling pathways involved. Western Blot analysis revealed that ERK1/2 and Akt (PKB) were activated after IGF-1 stimulation. The activation of ERK1/2 was reduced by the PI3K inhibitor Wortmannin, implying that the PI3K pathway is involved in its activation. Insulin-like growth factor-1 induced an increase in DNA synthesis in MM cells, which was mediated by a PI3K/Akt-MEK/ERK pathway. Insulin-like growth factor-1 enhanced F-actin assembly and this process was only PI3K mediated. Stimulation by IGF-1 of VEGF production was reduced by PD98059, indicating that only the MEK–ERK pathway is involved in IGF-1-stimulated VEGF production. In conclusion, IGF-1 mediates its multiple effects on MM cells through different signal transduction pathways. In the future, we can study the potential in vivo effects of IGF-1 inhibition on tumour growth and angiogenesis in MM.

Murine 5T multiple myeloma cells induce angiogenesis in vitro and in vivo

Multiple myeloma is a B cell malignancy. Recently, it has been demonstrated that bone marrow samples of patients with multiple myeloma display an enhanced angiogenesis. The mechanisms involved seem to be multiple and complex. We here demonstrate that the murine 5T multiple myeloma models are able to induce angiogenesis in vitro by using a rat aortic ring assay and in vivo by determining the microvessel density. The rat aortic rings cultured in 5T multiple myeloma conditioned medium exhibit a higher number of longer and more branched microvessels than the rings cultured in control medium. In bone marrow samples from 5T multiple myeloma diseased mice, a statistically significant increase of the microvessel density was observed when compared to bone marrow samples from age-matched controls. The angiogenic phenotype of both 5T multiple myeloma cells could be related, at least in part, to their capacity to produce vascular endothelial growth factor. These data clearly demonstrate that the 5T multiple myeloma models are good models to study angiogenesis in multiple myeloma and will allow to unravel the mechanisms of neovascularisation, as well as to test new putative inhibitors of angiogenesis.