Medical Imaging Workshop Molecular Imaging Marcelo Tatit Sapienza

Medical Imaging Workshop Molecular Imaging Marcelo Tatit Sapienza INFIERI Summer School Intelligent signal processing for Front. IER Research and Industry

Molecular Imaging • Overview • Imaging Modalities • Clinical Applications – e. g. breast cancer

Molecular Imaging MOLECULAR BIOLOGY In vivo Imaging visualisation, characterization and quantification of normal / pathological biological processes at the cellular and molecular level

MOLECULAR BIOLOGY Abnormal cells with pathological phenotypes Molecular expression Molecular paradigm of diseases

Hallmarks of cancer – Cell 2000 Hanahan & Weinberg

Abnormal cells with pathological phenotypes Molecular expression Probes / ligands may be detected and allow Therapy with labeled compounds Diagnosis Identification of targets for drugs Therapy planning Therapy response

Molecular Imaging BASIC / PRECLINICAL RESEARCH • • • Study of mechanisms of disease development and progression Detection and activity of receptors and pathways Pharmacokinetics / pharmacodynamics of target drugs CLINICAL APPLICATIONS • • • Understanding pathophysiological mechanisms Diagnosis / Staging Response to target drugs / individualized therapies

Translational research • Molecular Target Identification • Development of ligands Preclinical • Experimental / preclinical evaluation Clinical • Image in humans validation • Approval by regulatory agencies • Clinical application

Translational research from BENCH to BEDSIDE to public health

Molecular Imaging • Overview • Imaging Modalities • Clinical Applications – e. g. breast cancer

Imaging Modalities Optical systems Nuclear Medicine: PET / SPECT MRI Ultrasonography Computed tomography Differences in • • • Spatial resolution Depth of evaluation Ionizing / non-ionizing radiation Available molecular markers or probes Detection threshold

Imaging modalities Willmann Nature Reviews 2008

Imaging modalities Optical Imaging: lower cost high-throughput screening for targets low depth penetration limited clinical translation Nuclear Medicine: higher cost than optical unlimited depth penetration clinical translation MRI: high resolution and soft tissue contrast / cost and imaging time US: high spatial and temporal resolution / low cost / limited targets CT: high spatial resolution / no target specific imaging Willmann Nature Reviews 2008

Spectrum of wavelenghts Eletromagnetic radiation MRI Optical CT / NM Low energy High energy Infra red Ultra violet

Optical Imaging fluorescence and bioluminescence Green fluorescent protein Reporter gene (luciferase) Near Infrared fluorphores (NIR) Prescher Current Opinion in Chemical Biology 2010

NM Radiopharmaceuticals • radiolabeled molecules designed for in vivo application: 1. PHARMACEUTICAL= molecular structure determining the fate of the compound within the organism 2. RADIO= radioactive nuclide responsible for a signal detectable outside of the organism e. g. technetium-99 m half life 6 hours gamma-ray photon 140 ke. V

Scintillation camara Sorenson and Phelps, 27 1987 W. B. Saunders

SPECT Single Photon Emission Computed Tomography

Positron emitters Nuclides • F-18 • C-11 • N-13 • O-15 1 • Ga-68 • Rb-82 half life 110 min 20 min 10 min 2 min 68 min 1. 3 min Positron: -Same mass as electron -opposite electrical charge -annihilation generates a pair of gamma-ray photons – 180º

PET Zanzonico Semin Nucl Med 2004

SPECT PET 511 ke. V 140 ke. V SPECT / CT 511 ke. V PET / CT

PET SPECT PET > SPECT • Spatial resolution (human studies) • Temporal resolution • Sensitivity • Cost

Molecular Imaging Requirements - Imaging equipment - Target selection - Development of imaging probe / tracer

Development of in vivo probes < 5% of in vitro targets allow development of an in vivo tracer • High TARGET concentration – Affinity and specificity – Absence of biological barriers (i. e. endothelium, blood brain barrier, . . . ) – Stable labeling of compound

Development of in vivo probes < 5% of in vitro targets allow development of an in vivo tracer • High TARGET activity / concentration – Affinity and specificity – Absence of biological barriers (i. e. endothelium, blood brain barrier, . . . ) – Stable labeling of compound • Low BACKGROUND activity – Non-specific accumulation, – Circulating or interstitial activity – Renal or hepatic elimination

Development of in vivo probes < 5% of in vitro targets allow development of an in vivo tracer • High TARGET activity / concentration – Affinity and specificity – Absence of biological barriers (i. e. endothelium, blood brain barrier, . . . ) – Stable labeling of compound • Low BACKGROUND activity – Non-specific accumulation, – Circulating or interstitial activity – Renal or hepatic elimination • Signal amplification – Cell trapping – Enzymatic conversion – "Reporter" molecules: fluorescence, radiation, magnetic

EXAMPLE: 18 FDG fluorodeoxyglucose = glucose analogue • Transport (Glut) • Phosphorylation (hexokinase) • Metabolism

MOST TUMORS: Increased Aerobic glycolysis (Warburg effect ) Phenotype common to most tumors • Lower production of energy / mol X • NADPH Production - Synthesis • Hypoxia and acidosis select cells resistant to apoptosis • Acid p. H associated with invasion Vander Heiden Understanding the Warburg Effect Science 2009

Hanahan & Weinberg Cell 2011

Molecular Imaging • Overview • Imaging Modalities • Clinical Applications – e. g. breast cancer

Breast cancer • Brazil Most incident in women ~ 50 /100, 000 LOBULAR 57. 120 new cases ( 2014 – INCA ) deaths: 13. 345 ( 2011 – SIM ) 5 y survival ~ 60 % DUCTAL

Breast cancer Staging - T 1 < 2 cm AJCC Cancer Staging Manual. 7 th ed. 2010, T 2 2 -5 cm T 3 > 5 cm T 4 thoracic wall / skin - N 0, 1 axillary I-II mobile, N 2 axillary fixed or int. thoracic, N 3 infra (III) / supraclavicular / axillary+int. thoracic - Metastases M 0, M 1 PROGNOSIS and CONDUCT Therapy choices considers also : - Clinical conditions, Age , Menopause, Histology of the tumor - Hormone Receptors and HER 2

Hormone and Growth Factor Receptors expression variation PREDICTIVE biomarker = susceptibility of the tumor before indicating therapy

BIOPSY: TU hormone receptor ++ susceptible to treatment with drugs that blocks either the estrogen receptors or hormonal synthesis Biomarker-driven personalized cancer therapy BUT… Precision medicine

Establishing genetic and molecular profile by biopsy may not be sufficient: Tumor heterogeneity Gerlinger, Intratumor heterogeneity NEJM 2012

18 FES – FLUOROESTRADIOL target = hormone receptor FES FDG posttherapy PREDICTIVE biomarker in breast cancer ( indicates susceptibility to treatment ) Linden JCO 2006

18 FES – FLUORO ESTRADIOL FDG posttherapy Linden JCO 2006

EARLY RESPONSE biomarker = post-therapy prognosis PET- FDG in the metabolic evaluation after lymphoma chemotherapy • Reduce or increase # chemotherapy cycles • Change / add therapy Kasamon JNM 2007

18 F-FES – FLUOROTHYMIDINE target = DNA synthesis uptake after 1 st cycle identifies responders ( p 0. 001 ) - ( n= 15 ) EARLY RESPONSE biomarker in breast cancer Crippa F Eur J Nucl Med Mol Imaging 2015

18 F-FES – FLUORO THYMIDINE EARLY RESPONSE biomarker in breast cancer uptake after 1 st cycle identifies responders ( p 0. 001 ) - ( n= 15 ) Crippa F Eur J Nucl Med Mol Imaging 2015

Conclusion • Molecular imaging is a multidiciplinary field in the intersection of molecular biology and in vivo imaging • Main pillars of MI are : – Use of imaging modalities with different performances – Development of probes/ligands detectable in vivo • MI is part of translational research and may be applied for biomarker-driven personalized therapy ( precision medicine )

Thank you ! marcelo. sapienza@hc. fm. usp. br