EXONHIT INITIATES PHASE II CLINICAL TRIAL FOR EHT 0201.

ExonHit Therapeutics, Paris, France, the alternative splicing- based drug discovery company, has initiated its first clinical trial evaluating EHT 0201 (pentoxifylline) in patients suffering from Amyotrophic Lateral Sclerosis (ALS). The Phase II clinical trial will evaluate the safety and efficacy of EHT 0201 as a potential treatment in addition to Rilutek (riluzole, Aventis) therapy for patients suffering from ALS. The trial will take place in 12 centres in Europe.

ALS (also referred to as Motor Neuron Disease (MND), Charcot's disease or Lou Gehrig's disease) is a progressive and fatal neurological disease that affects 100,000 -120,000 people worldwide with about 1,200 new cases occurring in the UK each year. There is no cure for ALS, nor is there a proven therapy that will prevent or reverse the course of the disorder. The only drug approved today for ALS is Rilutek.

ExonHit Therapeutics is confident that EHT 0201 will be a positive step forward in the treatment of ALS because its development has been based on a better understanding of the molecular causes of the disease. This improved insight has been generated using ExonHit Therapeutics' DATAS technology. DATAS[TM] (Differential Analysis of Transcripts with Alternative Splicing) has systematically identified, in animal models of ALS, different tissue-specific RNA isoforms that are produced as a result of splicing changes that take place during the onset of the disease. This information has led ExonHit Therapeutics to discover a large number of new potential therapeutic targets, which are expected to offer better, more appropriate ways to treat ALS.

EHT 0201 was selected from a library of compounds for clinical development, following an evaluation of its pharmacological effects (including comparisons with riluzole) against a subset of these new molecular targets. EHT 0201 is being evaluated directly in patients suffering from ALS owing to its already well-characterised safety profile.

The Phase II trial being undertaken by ExonHit Therapeutics is a major study that will recruit up to 400 participants at 12 centres in Europe: one in Belgium, four in France, three in Germany, and four in the UK. It will be a double-blind, randomised, placebo-controlled study. Patients will be treated for 18 months. EHT 0201 (or placebo) will be administered in addition to Rilutek, a treatment that many ALS patients already receive as part of their standard care. First results of the study are expected by the end of 2004.

"We are very pleased to be starting this new clinical trial in ALS with ExonHit Therapeutics as this study offers hope of further progress in treating this devastating disorder," said Professor P. Nigel Leigh, Principal Investigator (Motor Neuron Disease Care and Research Centre, Kings College Hospital, London).

"Using our proprietary DATAS technology, we have been able to identify new therapeutic targets that are at work in the pre-symptomatic stage of the ALS disease model," commented Philippe Guillet, M.D., VP for Clinical Research at ExonHit Therapeutics, who played a major role in the clinical development of Rilutek. "It gives us a very strong positive feeling to start a new trial that may bring essential relief to patients."

"The start of this Phase II clinical trial underlines ExonHit Therapeutics commitment to rapidly develop new potential therapeutic alternatives for ALS patients. By moving from target identification to Phase II trials in less than one year, we have clearly demonstrated the value of our DATAS technology, in progressing drugs candidates into the clinic much faster than the industry norm," declared Bruno Tocque, CEO of ExonHit Therapeutics.

About ALS (also called Motor Neuron Disease (MND), Charcot's disease or Lou Gehrig's disease)

ALS is a progressive and fatal neurological disease characterized by a degeneration of motor neurons in the spinal cord, brain stem and cerebral cortex, leading to muscle wasting and weakness. It affects 100,000 to 120,000 people worldwide with 5,000 and 7,500 new cases occurring each year in the US and in Europe, respectively. There is no cure for ALS, nor is there a proven therapy that can prevent or reverse the course of the disorder. ALS affects all muscles under voluntary control resulting in sufferers losing the strength and the ability to move their arms, legs, and body. When respiratory muscles are affected, patients lose the ability to breathe without ventilatory support. 80% of ALS patients die from respiratory failure.

About ExonHit Therapeutics

ExonHit Therapeutics is a world-leading company in developing novel pharmaceuticals and diagnostics from its unique understanding of alternative RNA splicing, the process by which a single gene can lead to several proteins. The company's proprietary gene profiling technology DATAS(tm), allows the detection of the disease-relevant changes in mRNA population resulting from alternative splicing events, thus providing the most valuable biological information about the causes of pathology.

In order to fully capitalize on its cutting-edge DATAS technology, ExonHit Therapeutics has organized its activities into four business units:

In-House Therapeutics - The company is concentrating on the treatment of cancer and neurodegenerative diseases, and has four compounds under development: EHT 0201 and EHT 0202 for the treatment of ALS (Amyotrophic Lateral Sclerosis), and EHT 0101 and EHT 0102, for cancer. EHT 0201 entered clinical trials in October 2002.

Collaborative Therapeutics - The company has initiated two major R&D programs, with Allergan in ophthalmology and IDEC Pharmaceuticals to develop antibody therapies for prostate cancer.

Diagnostics and Pharmacogenomics - The company has entered a collaboration with Roche to develop a diagnostic test that can identify BSE in living animals. ExonHit Therapeutics is also developing a series of molecular cancer diagnostic tools (Proof-Hit) to predict patients who are most likely to respond to conventional chemo- and radiotherapies. The company is collaborating with BioMerieux-Pierre Fabre to develop Proof-Hit(tm) for colon and breast cancer.

Profiling - ExonHit Therapeutics has marketed a predictive toxicology array (Safe-Hit[TM]) to assist the pharmaceutical industry to concentrate its resources on the most promising compounds.

ExonHit Therapeutics, which was founded in 1997, has its headquarters and laboratories in Paris, France and its US operations are based in Gaithersburg, MD. The company has 75 employees worldwide and has raised a total of EUR47 million (US$42 million).

For more information, visit http://www.exonhit.com.