Prospective Application of CTFEA for Monitoring Disease Progression in Active Multiple Myeloma

Background

Multiple myeloma (MM) is the most common primary bone malignancy, caused by proliferation of plasma cells secreting immunoglobulins. Active MM (aMM) is characterized in many patients by multiple lytic bone lesions, presenting with pain in the involved bones (e.g. pelvis, spine, etc.). In a recent publication, key-opinion leaders of multiple-myeloma state "MM-induced bone disease is a hallmark of MM; up to 80% of patients present with osteolytic bone lesions at diagnosis and have an increased risk of skeletal-related events (SREs) associated with increased morbidity and mortality" (Terpos et al, 2018). Approximately 60% of myeloma patients will develop a fracture during the disease course" (Terpos et al, 2018). Current CT scans provide qualitative measures of bone involvement detected only after irreversible damage has occurred and which cannot predict disease evolution so to optimize treatment and enhance life quality and longevity.

Medical treatment modalities, including multi-agent chemotherapy and bone marrow transplantation, may stop progression of MM, and prevent further bone lesions. Myeloma response to therapy is usually monitored by measurement of the monocloncal protein which is secreted by the malignant plasma cells into the blood and urine. This protein includes an intact immunoglobulin - M-SPIKE - which is measured by serum protein electrophoresis (SPEP) and, Circulating free light chains - kappa and lambda. Usually one of the chains is "involved" in the disease; The level of M-SPIKE and the ratio of the "involved" to "uninvolved" chains is used to monitor disease progression. The role of imaging technologies in monitoring progression of the disease is less defined. Low-dose total body CT scans are recommended as second-line imaging (total body MRI is first-line) during the initial diagnostic workup of MM by the most current guidelines of National Institute for Healthcare Excellence (NICE, 2016). The guidelines encourage further research of the role of various imaging modalities in treatment of MM:

"Newer imaging techniques are replacing skeletal surveys for assessing myeloma related bone disease in people with newly diagnosed myeloma. However, the most effective tech-nique is not known. Outcomes of interest are lesion detection, sensitivity and specificity for myeloma related bone disease, patient acceptability, incremental upstaging, radiation exposure, risk of second primary cancer, the impact of additional information on predicting progression-free survival, overall survival and skeletal related events." (NICE, 2016) As previously stated, current imaging modalities visualize bone lesions but do not quantify their progression, any response to therapy or their impact on bone strength. A novel scientific tool that describes bone's response by mathematical equations and is based on CT scans of MM patients, allows to construct a 3-D model of patient's femurs and vertebrae including the inhomogeneous material properties, virtually loads the bones by physiological loads associated with patient's weight and determine the deformations and strains by a computer simulation. This technology, termed CTFEA, allows a quantitative evaluation of bone's strength and risk of fracture, was double-blinded validated ex-vivo, and clinically validated in a retrospective clinical trial on a cohort of 50 patients with metastatic tumors to their femurs (Sternheim et al, 2018).

Combining the engineering and scientific expertise with the clinical knowledge and database of MM patients accumulated during the past ten years, may identify by monitoring femurs' and vertebrae' strength the evolution of MM, and trigger the need of prophylactic surgeries. Such CTFEA has the potential to revolutionize MM treatment by providing the MDs quantitative scientific measures to monitor and change treatment options so to optimize medication prescription and enhance life-quality and longevity of MM patients on one hand, and determine with high level of accuracy the risk of impending fracture due to metastatic tumors to the femurs and vertebrae.