Kiadis Pharma today announced interim results of a physician initiated European Phase II clinical study for its lead product ATIR. Professor Velardi from the University of Perugia in Italy presented the successful treatment of thirteen end stage blood cancer patients with a mismatched bone marrow transplantation during the 5th workshop on "Haploidentical Stem cell Transplantation" in Catania, Italy. The results are an important milestone in the development of ATIR as a revolutionary approach to provide a safe and potentially life-saving mismatched bone marrow transplantation as treatment option for end-stage blood cancer patients.

Bone marrow transplantations are currently limited because of the high risk of Graft versus Host Disease (GvHD). This is a severe and potentially life-threatening complication in which the donor immune cells recognize and attack the patient's tissues and organs. Therefore it is currently essential that the patient and donor blood systems (the human leukocyte antigens, HLA) are highly similar in order to reduce the chance of acute GvHD. As a consequence, bone marrow transplantations strongly rely on the availability of a matching donor. However, the timely availability of a matching donor is a limiting factor for many patients to receive a bone marrow transplantation. Kiadis Pharma's ATIR is under development to prevent acute GvHD by elimination of the immune cells causing acute GvHD. A successful development would enable the performance of mismatched donor transplantations, including donor immune cells that can fight infections and the cancer without causing GvHD complications. Because ATIR eliminates acute GvHD causing cells, the transplantation can be performed without the currently standard immune suppressant regime post transplantation. This subsequently allows the donor immune system to rapidly develop helping the patient to fight infections, another major life threatening complication of bone marrow transplantations.

Professor Velardi, a key opinion leader in the field of mismatched allogeneic transplantations, has presented the clinical results of thirteen end stage blood cancer patients who received bone marrow transplants from mismatched donors, including donor immune cells that are selectively depleted of acute GvHD causing cells using ATIR. No immune suppressants were used post transplantation as a standard regime. No patient has developed lethal acute Graft versus Host Disease, the major complication that prohibits the use of this treatment without ATIR. The patients rapidly developed a new donor immune system as assessed by the rapid expansion of immune cells in the patients. Detailed analysis revealed the presence of pathogen specific donor immune cells in the patients. In particular immune cells recognizing pathogenic fungi, like Aspergillus and viruses like Cytomegalovirus (CMV) could be detected post transplantation.

These specific pathogens are the major cause of death by infections after bone marrow transplantation. This shows that the ATIR treated immune cells are functional and could fight infections without causing lethal acute GvHD in these patients.

"Bone marrow transplantations are often the only treatment option left for end-stage blood cancer patients. But too many patients simply do not find a suitable matched donor in time," said Dr. Andrea Velardi, M.D., Professor of Clinical Immunology at the University of Perugia. "The interim results of our study show a rapid immune reconstitution in transplanted patients provided with ATIR treated immune cells from mismatched donors. Without ATIR treatment this would not be possible because of the high risk of acute Graft versus Host Disease (GvHD) with mismatched donor immune cells. This is obviously a very hopeful development for a large patient group."

The physician initiated European ATIR Phase II trial by Prof. Andrea Velardi, M.D. is the second clinical trial of ATIR for mismatched bone marrow transplantations. Kiadis Pharma conducts a company-sponsored trial ongoing in North America. Both trials aim to investigate the potential of ATIR to make the use of a mismatched bone marrow transplantation a feasible treatment for blood cancer patients who are not responding to other treatments and who do not have access to a matched donor in time. For these patients ATIR can enable a potentially life-saving transplantation.

"The broad endorsement of ATIR by key opinion leaders in this field is exemplified by the initiative of Professor Velardi," commented Dr. Manja Bouman, CEO Kiadis Pharma. "These excellent results in the Perugia trial provide Kiadis Pharma with important external validation."

About ATIR

ATIR is being developed to enable the use of a mismatched donor for an allogeneic bone marrow transplantation for end stage blood cancer patients. ATIR selectively eliminates from a mismatched graft the immune cells that cause acute Graft versus Host Disease, a severe and potentially lethal complication with allogeneic bone marrow transplantations.

About Kiadis Pharma

Kiadis Pharma is an oncology focused pharmaceutical development company with four products in different phases of clinical development. The company develops products that offer novel treatment options for terminally ill cancer patients and address high-unmet medical needs. The key focus indication for Kiadis Pharma is limitations and complications of bone marrow transplantation procedures performed in blood cancer patients. Kiadis Pharma is headquartered in Amsterdam, the Netherlands with facilities in Groningen, The Netherlands and Montreal, Canada. For more information about Kiadis Pharma, please visit .