Early diagnosis of brain metastases using NMR metabolomics
James R Larkin, Alex M Dickens, Timothy D W Claridge, Alastair Hamilton, Emma O’Brien, Daniel C Anthony and Nicola R Sibson
Poster at 3rd Annual Brain Metastases Research and Emerging Therapy Conference, Marseille, France (2013)
Background: More than 1 in 5 cancer patients develop brain metastases. Current MRI diagnostic techniques only detect late stage metastases, since they rely on blood-brain-barrier permeability to allow gadolinium contrast enhancement. We have previously shown that it is possible to discriminate between different inflammatory lesions in the CNS in rats, as well as between different stages of multiple sclerosis in patients, through biofluid metabolomics. The aim here, therefore, was to determine whether the presence of brain metastases can be detected, in vivo, using NMR analysis of biofluids.
Methods: Metastatic mammary carcinoma cells (murine 4T1-GFP and human MDA-MB-231-BR) or murine melanoma B16F10 cells were injected into mouse brain (BALB/c, SCID and C57BL/6, respectively). 4T1-GFP cells were also injected via the heart or tail vein of BALB/c mice to induce differing cerebral and systemic tumour burdens. Urine was collected at days 0 and 10 from all animals, and at days 5, 28 and 35 in animals injected intracerebrally with 4T1-GFP cells. Samples from naive, day 0 and vehicle-injected mice served as controls. Samples were analysed using 1H-NMR spectroscopy, and statistical pattern recognition was applied to identify spectral differences.
Results: Significant separations were found between d0 and d10 animals for all 4T1-GFP injected mice irrespective of route (q2=0.51, 0.52 and 0.64 for intracerebral, intracardiac and intravenous routes, respectively). Significant separations were also seen between different time-points after intracerebral injection, and between animals injected via different routes (q2=0.72 for intracerebral vs. intracardiac; q2=0.86 for intracerebral vs. intravenous). Separations were also seen between animals injected with different cell types.
Conclusions: Our data indicate that animals with brain metastases can be identified using a biofluid-metabolomics approach, and differentiated from animals with a predominantly systemic metastasis burden. This approach may identify a set of biomarkers for the diagnosis of brain metastasis earlier than is currently possible.