Novel Oncologic Drugs: What They Do and How They Affect Images

Abstract

Targeted therapies are designed to interfere with specific aberrant biologic pathways involved in tumor development. The main classes of novel oncologic drugs include antiangiogenic drugs, antivascular agents, drugs interfering with EGFR-HER2 or KIT receptors, inhibitors of the PI3K/Akt/mTOR pathway, and hormonal therapies. Cancer cells usurp normal signal transduction pathways used by growth factors to stimulate proliferation and sustain viability. The interaction of growth factors with their receptors activates different intracellular pathways affecting key tumor biologic processes such as neoangiogenesis, tumor metabolism, and tumor proliferation. The response of tumors to anticancer therapy can be evaluated with anatomic response assessment, qualitative response assessment, and response assessment with functional and molecular imaging. Angiogenesis can be measured by means of perfusion imaging with computed tomography and magnetic resonance (MR) imaging. Diffusion-weighted MR imaging allows imaging evaluation of tumor cellularity. The main imaging techniques for studying tumor metabolism in vivo are positron emission tomography and MR spectroscopy. Familiarity with imaging findings secondary to tumor response to targeted therapies may help the radiologist better assist the clinician in accurate evaluation of tumor response to these anticancer treatments. Functional and molecular imaging techniques may provide valuable data and augment conventional assessment of tumor response to targeted therapies. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.317115108/-/DC1.

Assessment of Liver Tumor Response to Therapy: Role of Quantitative Imaging

“…Systemic chemotherapy plays an important role in treatment of metastatic liver disease, but its role remains limited in the management of hepatocellular carcinoma (1). Molecular-directed chemotherapies for hepatic metastatic disease and advanced hepatocellular carcinoma target specific biologic pathways, such as angiogenesis, tumor metabolism, and tumor proliferation (2). On the other hand, locoregional therapies have the advantage of treating malignant liver tumors without the risk of potential side effects from systemic chemotherapies.…”

PET/MR in Cancers of the Head and Neck

“…94 The derived measurements reflect blood volume, perfusion, and the intrinsic composition of tissues, providing information on microvasculature function. 95 This technique is still under development in patients with head and neck cancers, and further research is warranted. 58 As with other functional techniques, its value within a PET/MR protocol appears questionable at this time.…”

Quantitative volumetric functional MR imaging: an imaging biomarker of early treatment response in hypo-vascular liver metastasis patients after yttrium-90 transarterial radioembolization

“…Diffusion-weighted imaging (DWI) and the quantifiable apparent diffusion coefficient (ADC) detect motion of water within tumor tissues, which has been useful in tumor detection, characterization, and in monitoring response to treatment [11][12][13]. Previous studies have demonstrated that volumetric functional MR imaging can help in accurately assessing tumor response after loco-regional therapy (LRT) in patients with HCC, neuroendocrine liver metastases (NELM), and islet cell liver metastases (ICLM) [14][15][16].…”