Gaucher Disease: Problems and Solutions Seymour Packman, MD Department of Pediatrics Division of Medical Genetics Institute for Human Genetics University of California San Francisco

Gaucher Disease Type 1: Pathophysiology Deficiency of the lysosomal enzyme acid β- glucosidase Storage of glucosylceramide primarily in cells of the monocyte/macrophage lineage Progressive, multi-organ dysfunction primarily involving the reticulo- endothelial system Content from: M Judith Peterschmitt. Preclinical Information, Program Overview. 3/1/2011. Gaucher Cell Grabowski et al. MMBID Online. 2013. GMRB-0125-01

Clinical Manifestations of Gaucher Disease Type 1 Reflect Cellular Sites of Substrate Accumulation Monocytes Spleen Massive splenomegaly Cytopenia Hypermetabolic state: fatigue Marrow infiltration Cytopenia Macrophages Tissue macrophages Bone marrow Lung Infiltrative lung disease Hepatomegaly Liver Bone Kupffer cells (Hepatocytes spared) Alveolar macrophages Osteoclasts Avascular osteonecrosis Osteoporosis Pathological fractures Chronic bone pain Grabowski et al. MMBID Online. 2010. 4

Gaucher Clinical Presentation Patients with GD1 can present with any of these symptoms. Some may be severe and others completely absent. General symptoms: Fatigue Easy bruising/bleeding Menorraghia Decreased appetite Abdominal pain Bone pain (63%) Bone crisis (33%) Pathologic fracture (15%) Hepatomegaly (79%) Splenomegaly (87%) Joint collapse (8%) There is wide variability in the clinical presentation of type 1 Gaucher, with occasional discordance between visceral and bone involvement. Early signs and symptoms that a primary care provider may observe include abdominal pain, growth retardation, bruising/bleeding, anemia, and fatigue. As the disease progresses, common features may include hepatosplenomegaly and bone disease characterized by osteopenia, osteonecrosis, and bone pain in the advanced stage. Many of the signs and symptoms a primary care provider may see are shared with multiple other disorders. Anemia (64%) Thrombocytopenia (56%) Erlenmeyer flask deformity (46%) Osteonecrosis (25%) Osteopenia (42%) Bone marrow infiltration (40%) Charrow J et al., Arch Intern Med. 2000;160:2835. GMRB-0125-01 Clinical Involvement

Milestones in Gaucher Disease Treatment First recombinant human glucocerebrosidase ERT approved in US (Cerezyme®) in 1994 and in EU in 1997 2011: Placebo- controlled trial of eliglustat completed in treatment-naïve GD1 patients 1985: Glucocerebrosidase gene (GCB) cloned1 and mapped to chromosome 1q211,2 2003: IND filed for GZ-112638 (eliglustat) 2012 1980 1990 2000 2010 1983: First patient with GD1 treated at NIH with glucocerebrosidase purified from human placenta 1991: First placental-derived glucocerebrosidase ERT approved in US and EU (Ceredase ® ) 2003: First SRT approved in patients with GD1 for whom ERT is not an option (Zavesca®) Mainstay of treatment has been enzyme replacement therapy, which requires intravenous infusions typically administered every 2 weeks Development of an oral drug that can treat the broad GD1 population is highly desirable. Eliglustat is currently in late-stage clinical development as an oral substrate reduction therapy for the treatment of GD1 IND=Investigational New Drug; ERT= enzyme replacement therapy; GD1=Gaucher disease type 1 1. Sorge. PNAS, 1985:82:7289; 2. Ginns, PNAS 1985;82:7101. 6

Approved Treatments for Gaucher Disease Alglucerase (Ceredase®); purified human placental enzyme. Approved in 1991; no longer available Imiglucerase (Cerezyme®); recombinant human enzyme; produced in CHO cells. Approved in 1994. Velaglucerase alfa (Vpriv®, Shire); recombinant human enzyme, produced in human cells. Approved in 2010. Taliglucerase alfa (ElelysoTM, Pfizer/Protalix), recombinant human enzyme, produced in carrot cells Approved in 2012 GMRB-0125-01

ENZYME REPLACEMENT THERAPY Replacement of defective enzyme with normal genetically engineered enzyme Engineered enzyme is tagged with a specific recognition signal for delivery to appropriate cell or organelle Administration by intermittent IV Leave enough time for this - this is an important concept!

Mannose-6-Phosphate Receptor System P Lysosome P = Mannose-6-P P Trans Golgi P Rough ER Cis Golgi

GAUCHER DISEASE Enzyme Replacement Therapy  hemoglobin in a few months  platelets  organomegaly in ~ 6 months  bone pain, bone crises Slow change of bone X-ray abnormalities

Approved Treatments for Gaucher Disease Substrate reduction therapy (SRT); oral administration Zavesca® (miglustat, Actelion); imino sugar-based analogue Approved in 2003. Indicated only for adults with mild to moderate Gaucher disease who are unable or unwilling to receive ERT Cerdelga ® (eliglustat, Genzyme); ceremide-based analogue Approved in 2014 Indicated for the longterm treatment of adult patients with Gaucher disease type 1 who are CYP2D6 extensive metabolizers (EMs), intermediate metabolizers (IMs), or poor metabolizers (PMs) as detected by a genetic test GMRB-0125-01

Restoring a Balance Between GL-1 Substrate Synthesis and Degradation Synthesis (S) & Degradation (D) of glucosylceramide (GL-1) Normal Gaucher Gaucher Disease + ERT + SRT S D Shayman JA. ELIGLUSTAT TARTRATE: Glucosylceramide Synthase Inhibitor Treatment of Type 1 Gaucher Disease. Drugs Future 2010;35:613-20. Two treatment approaches have been used to lower GL-1 accumulation in Gaucher disease. In both approaches, the goal is to restore the balance between synthesis and degradation of GL-1. Enzyme replacement therapy (ERT) with recombinant acid ß-glucosidase augments the patient’s enzyme activity to break down accumulated GL-1. Substrate reduction therapy (SRT) inhibits glucosylceramide synthase (GCS), thereby slowing down the production of GL-1. For graphic illustration purposes only. ERT=enzyme replacement therapy; SRT=substrate reduction therapy. Shayman. Drugs Future. 2010:35:613.

Zavesca (miglustat) Effective in Gaucher treatment FDA approved if cannot use ERT Adverse reactions: - peripheral neuropathy (tingling, numbness, burning) - tremor (30%) - diarrhea (85%; reduce high CHO) - mild weight loss (65%)

miglustat

Eliglustat (Cerdelga) Mechanism of Action Glucosylceramide Synthase Acid β-glucosidase Deficient in Gaucher disease Eliglustat Ceramide + Glucose Glucosylceramide Enzyme Replacement Therapy Shayman. Drugs Future. 2010:35:613. Shayman JA. ELIGLUSTAT TARTRATE: Glucosylceramide Synthase Inhibitor Treatment of Type 1 Gaucher Disease. Drugs Future 2010;35:613-20. Gaucher disease type 1 (GD1) is an inherited, multi-systemic lysosomal storage disorder characterized by deficient activity of the enzyme acid β-glucosidase. This results in progressive accumulation of the enzyme substrate (glucosylceramide, GL-1) in lysosomes of tissue macrophages, causing hepatosplenomegaly, anemia, thrombocytopenia, and bone disease. Two treatment approaches have been used to restore the balance between synthesis and degradation of GL-1 in GD1. Enzyme replacement therapy (ERT) with recombinant acid β-glucosidase augments the patient’s enzyme activity to break down accumulated GL-1. Substrate inhibition therapy (SRT) inhibits glucosylceramide synthase and slows the production of GL-1. Eliglustat is a novel oral SRT in development for adults with GD1. It resembles the ceramide moiety of GL-1, and acts by specifically inhibiting glucosylceramide synthase, resulting in decreased accumulation of the substrate GL-1. GMRB-0125-01

Eliglustat Tartrate is a Novel Analog of Glucosylceramide OH HN O HO N O HN OH Earlier substrate inhibitors studied, such as miglustat, were primarily analogs of glucose. In contrast, Eliglustat tartrate is an analog of glucosylceramide. Glucosylceramide Eliglustat tartrate Ver. 10 May2010

Inhibitors of Glucosylceramide Synthase Content from: M Judith Peterschmitt. Preclinical Information, Program Overview. 3/1/2011. GMRB-0125-01

Mannose-6-Phosphate Receptor System P Lysosome P = Mannose-6-P P Trans Golgi P Rough ER Cis Golgi

Chaperones

Chaperones

SMALL MOLECULES: CHAPERONES Stabilize mutant enzyme Increase β-glucocerebrosidase levels in Gaucher patients’ cells In development for Gaucher In phase III clinical trial for other lysosomal disorders

TREATMENT APPROACHES for LYSOSOMAL DISORDERS Enzyme replacement Novel biochemical measures substrate reduction chaperones other small molecules: regulate gene expression or protein function; encapsulated cells

…out of nature’s certain course, A gift that rather was come late than soon. W. Wordsworth