**6.2 Recombinant mammalian/human lipases**

Owing to rapid development of plant biotechnology in recent times, Merispase a recombinant mammalian gastric lipase was produced in transgenic corn by Meristem Therapeutics and proposed as new oral substitute for the treatment of pancreatic insufficiency. Dog gastric lipase was selected because it is naturally resistant to inactivation by stomach acids and maintains a high enzymatic activity after passage through the stomach. Enzyme expression was stable over 11 generations with an approximate level of 1,000 mg kg-1 kernel (Shama & Peterson, 2008). According to Fieker et al. (2011), this approach could be problematic for several reasons: gastric lipase specific activity is about 10 times lower than that of pancreatic lipase (measured on tributyrin), it is highly sensitive to trypsin proteolysis, and endogenous secretion of gastric lipase can be increased in patients with pancreatic insufficiency because of possible nutritional adaptation. Meanwhile, clinical trials showed that the recombinant gastric lipase is well tolerated and efficient when administered either alone or combined with porcine pancreatic extract to patients with cystic fibrosis (Fieker & al., 2011, as cited by Lenoir et al., 2006, 2008). The highest efficiency is obtained when 250 mg of recombinant gastric lipase is associated with low dose of pancreatic extract (Fieker & al., 2011, as cited by Lenoir et al., 2008). Despite these encouraging results, Mersitem therapeutics went out of business in September 2008 while the product was blocked in clinical phase II trial.

Expected to offer superior safety by decreasing the risk of allergic reactions, recombinant human bile salt- stimulated lipase was suggested as promising candidate for the treatment of lipid malabsorption in pancreatic insufficiency. Human bile salt-stimulated lipase is naturally acid resistant and able to: (i) hydrolyze triglycerides and phospholipids (Lindquist & Hernell, 2010) (ii) generate lysophospholipids necessary for an efficient lipid absorption rate by the small intestine (Fieker & al., as cited by Tso, 1994) (iii) participate in chylomicron assembly and secretion through its ceramidase activity (Hui and Howles, 2002). For these reasons, Swedish Orphan Biovitrum - a leading company focused on treatment of rare diseases developed two preparations of recombinant bile salt-stimulated lipase: Kiobrina for preterm infants and

 (NDA) to ensure consistent efficacy, safety, and quality of these agents (US Food and Drug Administration, 2006). Therefore, in order to comply with the FDA 2004 mandate, several studies have been recently conducted to ensure safety and effectiveness of some new reformulated pancreatic enzyme supplements such as Creon® 24,000 and EUR-1008 (Zenpep™) (Wooldridge & al., 2009; Trapnell & al., 2009). Nevertheless, these products of animal origin present yet a risk of viral transmission. Accordingly, there remains a need for

Even though bovine enzymes have been suggested as a potential alternative for individuals who refuse to consume porcine products for religious or other cultural reasons; there remain some safety concerns about transmittable pathogens such as Foot and mouth disease and Bovine spongiform encephalopathy from these preparations. Additionally, lipase activity is

Owing to rapid development of plant biotechnology in recent times, Merispase a recombinant mammalian gastric lipase was produced in transgenic corn by Meristem Therapeutics and proposed as new oral substitute for the treatment of pancreatic insufficiency. Dog gastric lipase was selected because it is naturally resistant to inactivation by stomach acids and maintains a high enzymatic activity after passage through the stomach. Enzyme expression was stable over 11 generations with an approximate level of 1,000 mg kg-1 kernel (Shama & Peterson, 2008). According to Fieker et al. (2011), this approach could be problematic for several reasons: gastric lipase specific activity is about 10 times lower than that of pancreatic lipase (measured on tributyrin), it is highly sensitive to trypsin proteolysis, and endogenous secretion of gastric lipase can be increased in patients with pancreatic insufficiency because of possible nutritional adaptation. Meanwhile, clinical trials showed that the recombinant gastric lipase is well tolerated and efficient when administered either alone or combined with porcine pancreatic extract to patients with cystic fibrosis (Fieker & al., 2011, as cited by Lenoir et al., 2006, 2008). The highest efficiency is obtained when 250 mg of recombinant gastric lipase is associated with low dose of pancreatic extract (Fieker & al., 2011, as cited by Lenoir et al., 2008). Despite these encouraging results, Mersitem therapeutics went out of business in September 2008 while

Expected to offer superior safety by decreasing the risk of allergic reactions, recombinant human bile salt- stimulated lipase was suggested as promising candidate for the treatment of lipid malabsorption in pancreatic insufficiency. Human bile salt-stimulated lipase is naturally acid resistant and able to: (i) hydrolyze triglycerides and phospholipids (Lindquist & Hernell, 2010) (ii) generate lysophospholipids necessary for an efficient lipid absorption rate by the small intestine (Fieker & al., as cited by Tso, 1994) (iii) participate in chylomicron assembly and secretion through its ceramidase activity (Hui and Howles, 2002). For these reasons, Swedish Orphan Biovitrum - a leading company focused on treatment of rare diseases developed two preparations of recombinant bile salt-stimulated lipase: Kiobrina for preterm infants and

approximately 75% lower than the porcine preparations (Layer and Keller, 2003)

new alternatives to treat correctly exocrine pancreatic insufficiency.

**6. Enzyme replacement therapy: What's in the pipeline?** 

**6.2 Recombinant mammalian/human lipases** 

the product was blocked in clinical phase II trial.

**6.1 Bovine enzymes** 

Exinalda for cystic fibrosis patients. A phase I clinical trial showed that addition of recombinant bile salt-stimulated lipase to standard pancrelipase (Creon) enabled a dose reduction of pancrelipase. The treatment had the advantage of restoring a normal level and pattern of plasma chylomicron secretion (Fieker & al., 2011, as cited by Strandvik et al., 2004). The combined results from two Phase II studies evaluating Kiobrina in preterm infants demonstrated an increase in growth velocity and uptake of long chain polyunsaturated fatty acids such as docosahexanoic acid and arachidonic acid. The safety and tolerability profile of rhBSSL added to formula was similar compared to placebo (Maggio et al., 2010). Based on these encouraging results, Swedish Orphan Biovitrum enrolls in August 2011 the first patient in Kiorbina phase III clinical trial. An open-label exploratory phase II study on Exinalda (rhBSSL) in patients with cystic fibrosis and pancreatic insufficiency has been completed. The aim was to study the effect of Exinalda on fat absorption as well as safety in this patient population. The results showed that Exinalda is safe and tolerable at a dose level of 170 mg three times a day. In terms of efficacy (coefficient of fat absorption CFA) the primary endpoint was not met. Swedish Orphan Biovitrum is now assessing options to continue the development (Swedish Orphan Biovitrum website www. sobi.com).
