Press Release:

CYTOCHROMA ANNOUNCES POSITIVE COMPARATIVE DATA ON CTA018 IN CHRONIC KIDNEY DISEASE MODEL

CTA018 Confers Therapeutic and Safety Advantages Over Current Therapies

Markham, Ontario, Canada — November 6, 2008 — Cytochroma today announced positive comparative data on a novel vitamin D analog, CTA018, at the 2008 Annual Meeting of the American Society of Nephrology (ASN) in Philadelphia.  In preclinical models, CTA018 has demonstrated advantages over two marketed vitamin D hormone replacement therapies, calcitriol and paricalcitol (Zemplar®), the latter currently being the most widely used therapy for secondary hyperparathyroidism (SHPT) in the United States (U.S.).  These data were presented in a poster presentation entitled “The Metabolic Profile of CTA018 Confers Therapeutic and Safety Advantages over Current Therapies in an Adenine-Induced Model of Chronic Kidney Disease (CKD).”

Martin Petkovich, PhD, Cytochroma’s Chief Scientific Officer, stated, “CTA018 shows characteristics in a well-accepted preclinical model of uremia which strongly indicate that it will offer clear advantages to CKD patients over currently approved therapies.  We look forward to seeing these advantages confirmed in ongoing and future clinical studies with CTA018 Injection.”

The newly disclosed data support the following four conclusions regarding CTA018:

(1) CTA018 is a Potent VDR Agonist and CYP24 Inhibitor
CTA018 is a dual action active vitamin D analog. Like currently approved vitamin D therapies for SHPT, CTA018 is a potent activator of the vitamin D receptor (VDR), but unlike current therapies, it is also a potent and specific inhibitor of CYP24, the vitamin D catabolic enzyme.  Data presented today at the ASN demonstrate that CTA018 is at least 10 times more effective than calcitriol and paricalcitol in activating the VDR, and over 7 times more effective in inhibiting CYP24 than ketoconazole, one of the most potent CYP24 inhibitors known.

(2) CTA018 has a Short Half-Life in Human Enterocytes
Currently marketed vitamin D hormone replacement therapies (paricalcitol, doxercalciferol and calcitriol) can over-stimulate intestinal absorption of dietary calcium and phosphate, leading to excessive calcium and phosphorus in the blood.  These toxicities severely limit the ability of physicians to fully control SHPT with such therapies. Data presented today demonstrate that CTA018 has significantly reduced activity and half-life in human enterocytes (intestinal cells), making CTA018 Injection far less likely to cause hypercalcemia (excessive blood calcium) or hyperphosphatemia (excessive blood phosphorus).

(3) CTA018 Preserves Vitamin D Status
Currently available vitamin D hormone replacement therapies exacerbate vitamin D insufficiency, which is widespread in CKD patients.  Repeated administration of these therapies induces CYP24, and consequently depletes blood levels of calcifediol, a condition known as vitamin D insufficiency.  Vitamin D insufficiency has been linked to increased mortality in CKD patients.   In a preclinical study of adenine-induced CKD, repeated dosing with CTA018 did not decrease blood levels of calcifediol, possibly due to its potent CYP24 inhibitory activity.

(4) CTA018 Has Constant Potency and a Wider Therapeutic Window than Paricalcitol
Current vitamin D hormone replacement therapies can induce treatment resistance in CKD patients over time.  Prolonged dosing often induces CYP24 to levels that create a barrier to administered therapy, limiting effectiveness.  In a preclinical study of adenine-induced CKD, CTA018 was found to have consistent effectiveness in lowering parathyroid hormone (PTH) throughout a 4-week treatment period.  In contrast, paricalcitol became progressively less effective.  Additionally, CTA018 exhibited a wider therapeutic window than paricalcitol, having no significant impact on serum calcium or phosphorus at doses which fully controlled SHPT.

Current Status of CTA018 Injection

CTA018 Injection is in Phase II clinical development for the treatment of SHPT in CKD patients undergoing dialysis.  In Phase I, CTA018 Injection was well tolerated and produced clinically meaningful reductions in blood levels of PTH after less than two weeks of administration.  No clinically relevant elevations in serum calcium or phosphorus were observed.

Cytochroma has granted Mitsubishi Tanabe Pharma Corporation (MTPC) exclusive rights to CTA018 in the U.S. and Asia.  The companies have a co-development and co-promotion partnership in the U.S., whereas in Asia, MTPC has sole responsibility for development and commercialization in exchange for royalties.

About CTA018

CTA018 is the first compound in a new class of vitamin D hormone analogs having a novel dual mechanism of action.  CTA018 is designed to be a strong activator of the vitamin D signaling pathway as well as a potent inhibitor of CYP24, the intracellular cytochrome P450 enzyme responsible for inactivation of vitamin D hormones.  Based on its mechanism of action, CTA018 is expected to be safer and more effective in treating SHPT than currently available therapies.  CTA018 was designed by Professor Gary H. Posner, Ph.D. and is protected under patents and patent applications exclusively licensed to Cytochroma from the Johns Hopkins University.

About Chronic Kidney Disease

According to the National Kidney Foundation, more than eight million patients in the U.S. suffer from moderate CKD (Stages 3 and 4) to severe CKD (Stage 5).  Stages 3 and 4 are characterized by progressively decreasing kidney function as measured by glomerular filtration rate.  In Stage 5, kidney function is minimal to altogether absent and patients require regular dialysis or a kidney transplant for survival.  An estimated 70-90% of CKD patients have vitamin D insufficiency, which can lead to SHPT and resultant debilitating bone diseases.  Mounting evidence continues to link vitamin D insufficiency with progression of CKD and death.  CKD is caused most frequently by diabetes or hypertension, both of which are consequences of a growing obesity epidemic in countries worldwide. 

About Secondary Hyperparathyroidism

SHPT is a condition commonly associated with CKD in which the parathyroid glands secrete excessive amounts of PTH.  Excess PTH secretion arises as a result of impaired kidneys that are neither able to produce sufficient quantities of vitamin D hormones to suppress excessive PTH secretion nor maintain a state of balance (homeostasis) between calcium and phosphorus in the body.  Prolonged elevation of PTH causes excessive calcium to be released from bone into the blood, leading to softening of the bones (osteomalacia) and calcification of vascular tissues.  SHPT affects 40-60% of patients with moderate CKD and approximately 90% of patients with severe CKD.

About Mitsubishi Tanabe Pharma Corporation

Mitsubishi Tanabe Pharma Corporation (MTPC) is a research-driven global biopharmaceutical leader based in Japan, specializing in research, development and marketing of globally competitive pharmaceutical products focused on cardiovascular and metabolic disorders, and immune and inflammatory diseases.  In particular, MTPC strategically focuses on drug discovery in the field of diabetes including a broad range of clinical states from metabolic risks (obesity/dyslipidemia) to complications (renal dysfunction/dialysis) and stroke, including the total range of disease phases such as acute phase, convalescence and maintenance.  MTPC is currently developing two Phase III clinical candidates in the U.S. and EU: MP-146 for CKD and MCI-196 for hyperphosphatemia.

MTPC, established through the merger of Tanabe Seiyaku Co., Ltd. and Mitsubishi Pharma Corporation in October 2007, is committed to protecting the health of people around the world and contributing to comfortable lifestyles through creating pharmaceuticals.

For more information about MTPC, please visit www.mt-pharma.co.jp.

About Cytochroma

Cytochroma is a clinical stage specialty pharmaceutical company focused on developing and commercializing proprietary products to treat and prevent the clinical consequences of vitamin D insufficiency and SHPT associated with CKD.  The Company’s vitamin D-based therapeutics are designed to safely and effectively treat patients with Stage 3, 4 or 5 CKD.  Cytochroma has three lead product candidates in development for CKD patients: CTA018 Injection and CTAP201 Injection are being developed for the treatment of SHPT, while CTAP101 Capsules are being developed for the treatment of vitamin D insufficiency.  In addition, Cytochroma is developing novel therapies to treat hyperphosphatemia in these same patients.

For information contact:

Cytochroma Investors:
Gordon Ngan
Executive Director, Corporate Development
Tel: +1 (905) 479-5306 ext. 333
gordon.ngan@cytochroma.com

Cytochroma Media:
Robert Stanislaro (FD)
Tel: +1 (212) 850-5657
robert.stanislaro@fd.com

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