Overview of Current and future Contrast Agent and Statistical and design issues in clinical development of contrast agents Kohkan Shamsi, MD, PhD President, Symbiotic Pharma Research Pine Brook, NJ, USA Former affiliation: Berlex Inc, Montville, NJ

Current Imaging Techniques X-rays Ultrasonography Computed Tomography (CT) Magnetic Resonance Imaging (MRI) Nuclear Medicine (SPECT/PET) combination e.g. PET-CT

Iodinated contrast agents Agents come in different concentrations: Denoted by number after name (e.g. Ultravist 300) Number indicates mg iodine / mL of solution Different brands have different concentrations most common used conc. is 300mg/mL extensively used in Computer tomography Computer tomography is very widely used technique

The MRI-Contrast Agents Extracellular CM Blood-Pool CM Targeted/Intracell ular CM Targeted CM * Magnevist OMNISCAN Optimark + Gadovist 1.0 Protein-binding MS 325 BR 22 Macromolecular Gadomer P792 High-Reflexivity CM USPIO Supravist Combidex Hepatocyte-specific + Primovist Multihance Fibrin-targeted EP-2104 RES-specific + Resovist Plaque-imaging Gadofluorin + RES-specific * Feridex MRI CM * Approved in the USA + Approved in Europe Early Stage

Gadolinium: first MR contrast agent Magnevist was first MR contrast agent >60 million injection experience gadolinium compounds are very safe

MR Blood-Pool Agents Extracellular Contrast Agents e.g. Magnevist Intravascular Contrast Agents Ec Iv

USPIO ltrasmall uper- aramagnetic ron xide particles, coated with carboxydextran Optimized formulation for T1 w-imaging (MRA) USPIO 60 nm 20 nm SPIO nm Erythrocyte USPIOUSPIO

Blood-Pool Agents Gd-Based Gadolinium Chelates (Paramagnetic) Strong Protein BindingMacro-Molecules (no PB) MS-325 SAG/Epix B-22956/1 Bracco Gadomer 17 Schering P-792 Guerbet No contrast agent has been approved by FDA for MRA

Potential indications for blood pool agents Potential indications MRA Cardiac Tumor angiogenesis Venography Open magnets (interventions) GI bleeding Neurological applications Whole body imaging Other?

MS-325 enhanced MRI

High resolution MRA: imaging of vessel wall

Targeted agents for cells and for structures

Liver-specific MRI-CM WhitenersWhiteners Imaging with T1-Effect Multihance ® (Gd-BOPTA) Teslascan ® (Mn-DPDP) Primovist ® (Gd-EOB-DTPA) Specific CM for Hepatocytes Specific CM for RES Blackeners Imaging with T2-Effect Feridex ® (SPIO) Resovist ® (SHU 555 A)

Metastases Pre T1-GRE Post Mn-DP T1-GRE Pre FSE T2 Mangofodipir trisodium (Mn-DpDp):

Gd-BOPTA enhanced MRI and liver metastases PRE-DOSE POST-DOSE 40 min 120 min Courtesy of: R. Caudana,Verona, Italy

Metastases: Gd-EOB-DTPA enhanced MRI T1 w precontrast Flash 3 D postinjection (10min) additional metastasis (blue arrow) Courtesy of Prof. Hosten, Greifswald, Germany

Hemangioma with hepatocyte specific contrast agent (Gd-EOB-DTPA) T1w VIBE art T2w VIBE pv VIBE 20 min T1w 20 min precontrast dynamic hepatocyte phase Courtesy of C. Czech, Munich, Germany page 16

Pre T 1 Pre T 2 Post T 2 Metastases Resovist ® Lesion Detection Robinson, MD, Leeds, UK

Thrombus enhancing agent P-2104R Indications Pulmonary Embolism (PE) Deep venous thrombosis (DVT) Thrombus in left atrial appendage Venous coronary bypass grafts (CABG) Sinus vein thrombosis Mesenteric and portal thrombosis or emboli aorta 1h thrombus Plaque in Balloon-injured rabbits after high- cholesterol(Mcdonanld) diet Courtesy : Johnstone et al, Beth Israel/Deaconess Medical Center

Plaque imaging: Gadofluorine M New water soluble, macrocyclic gadolinium chelates Micelle formation and longer half life, high relaxivity

Plaque Imaging Gadofluorine M WHHL Rabbit IR turbo FLASH (300/4/120/20°) 24 h post injection

Immune-Mediated Nerve Injury (EAN) 6d after EAN, 24h after Gadofluorine, thigh Peripheral Nerve Imaging Potential applications: Structural nerve damage in Polyneuropathies Nerve trauma, Visualization of the progress of Nerve regeneration

Clinical trial design issues Dose finding in dynamic changing technology environment minimal effective dose identification that is based on development of machines Efficacy criteria: sensitivity, specificity and accuracy vs. ROC interpretation of the data inter reader variability (kappa statistics) clinical practice vs. blinded read. FDA looks only at the BR data standard of reference (is usually old and is not really gold) lesion tracking across test modalities and SOR 3-4 efficacy evaluations for each patient (site evaluation blinded reader evaluation) leads to multiple primary endpoints (e.g. 3 sensitivities, 3 specificities and 3 accuracies lead to multiple permutation and combinations