Ladies and gentlemen,

Please find below the new Absorber Newsletter regarding the meeting in Chicago which was held to discuss AbSorber’s endothelial crossmatch test, XM-ONE, November 6, 2010.

Thank you for your attention and best regards

Julia Hirtle
Sales and Marketing Manager Distribution

Clinical Use Of XM-ONE^® Discussed At Olerup, Inc. Advisory Board Meeting In Chicago, IL.

Improving outcomes in kidney transplantation: Non-HLA antibodies and Enhanced Clinical Risk Assessmen

On Nov 6, 2010 a meeting was held in Chicago to discuss AbSorber’s endothelial crossmatch test, XM-ONE^®, which is distributed in the Americas by Olerup, Inc. In attendance were 15 invited transplant surgeons and nephrologists from leading programs across the United States. The meeting was co-chaired by Professor’s Ron Shapiro of the University of Pittsburgh Medical Center, and Joseph Leventhal from the Northwestern University Feinberg School of Medicine.

“This was a very interesting meeting that provided updated data on the use of the anti-endothelial antibody test. More information will need to be gathered to establish with better precision the role of this test in clinical practice,” Professor Shapiro stated when closing the meeting

The Development Of XM-ONE^®, The Only FDA Approved Crossmatch Available For Non-HLA Testin

Professor Jan Holgersson from Sahlgrenska University Hospital, Gothenburg, Sweden, started by presenting the background facts and rationale for the development of the assay. In the early 90’s a girl receiving a kidney transplant at Karolinska Hospital, Stockholm, Sweden developed a hyper acute rejection and lost the graftwithin hours after transplantation. This was subsequently repeated and in parallel this also occurred in another child transplanted at the same center. Both these patients were negative in the standard tests and were shown to have non-HLA anti-endothelial cell antibodies. The researchers found that these cells expressed Tie-2 receptors on the cell surface and that Tie-2 positive antibodies could be used to isolate the cells. These findings have thereafter been explored and developed by AbSorber, and FDA approval was granted in 2008.

Fig. 1

Dr Håkan Hall, Head of Research and Development at AbSorber continued by presenting clinical data and focused on a multicenter study published in Transplantation (Breimer et al, Transplantation, Feb 2009). In the study it was clearly demonstrated that patients being XM-ONE^® positive pre-transplant had an increased risk of having acute rejections, compared to patients being XM-ONE^® negative (46% vs 11%, p<0.005, fig.1). Furthermore, in the XM-ONE^® positive patients all rejections occurred within the first three weeks post transplantation

Dr Hall also presented data from Sweden comparing PRA levels to XM-ONE^® positivity/negativity in patients awaiting kidney transplantation. These results indicated that there was a correlation between XM-ONE^® positivity and PRA levels. In patients with >10% PRA, they were XM-ONE^® positive in 48% of the cases, compared to 24% if PRA levels were <10%. However, in actual numbers there were more patients being XM-ONE^® positive among patients with low sensitization (PRA <10%), compared to highly sensitized patients (PRA>10%).

In the multicenter study (Breimer et al) patients that were PRA positive (PRA >10%) before transplantation did not have an increased risk of acute rejections. In the study PRA levels did not significantly impact the rejection frequency (Table 1) but rather the XM-ONE^® result. Also in this study the “low risk patients”, i.e. patients having a PRA<10%, were the largest group of patients at risk of having a rejection.

Table 1

Ongoing Single Center Study At Northwestern, Interim Report

Dr Joseph Leventhal, Northwestern University, Chicago, IL, presented two datasets, one from a pilot study of 53 patients, and the second from an ongoing prospective ongoing that has thus far recruited 130 patients. In their first study they found that approximately 20% of their patients were tested positive using the XM-ONE^® assay, despite being negative for HLA-DSA and MICA-DSA The prospective study, which is currently ongoing, has so far enrolled 130 patients, with clinical data being available for 93 patients having reached at least one month of follow-up. In these patients elevated Serum Creatinine above 2mg/dl was found in 42% of the XM-ONE^® positive patients (5/12) compared to 15% of the negative patients (12/81, Fig.3). Data on Acute Rejection Episodes are yet to be evaluated.

Dr Markus Gäbel, Sahlgrenska University Hospital, Gothenburg, Sweden, presented a four year data follow up on their patients included in the multicenter study. In the data set, which included a total of 53 patients, almost half of the group had received a kidney from a deceased donor, showing that deceased donors can be XM-ONE^® tested in a secure way. In the Gothenburg data 13% of the patients were positive in XM-ONE^® and among those 71% had a rejection during the first three weeks post transplantation. In the XM-ONE^® negative group, the rejection rate was 11%. When evaluating the long term data in patients being XM-ONE^® positive pre transplant, there was a significantly increased serum creatinine one year after transplantation. However this difference, when compared to XM-ONE^® negative patients disappeared greater that one year post transplantation. The Board speculated that this was due to the rejections aggressively being identified and treated at an early stage, thereby avoiding delay in diagnosis and treatment. The Board also encouraged the presenter to look further into the data.