Results from a retrospective study demonstrate that a set of protein bio­markers found in urine can be used to predict the development of acute graft-versus-host disease in patients who undergo donor stem cell trans­plan­ta­tion.

During the study, levels of specific urine proteins were used to generate a "classi­fication factor," named aGvHD_MS17, designed to predict a pa­tient's probability of developing acute graft-versus-host disease (GVHD).

The study's findings may allow for early detection and preemptive treat­ment of acute GVHD, a potentially fatal complication that can occur after trans­plan­ta­tion using donor stem cells.

“The most important finding is that a life-threatening complication like graft-versus-host disease can be diagnosed in urine about 10 days prior to any clinical symptoms,” said the study’s lead investigator, Dr. Eva Weissinger of the Hannover Medical School in Germany. “Now we can diagnose pending severe graft-versus-host disease very early and have time to act and treat the patients preemptively with exogenous steroids,” explained Dr. Weissinger.

Background

Donor (allogeneic) stem cell trans­plan­ta­tion has the potential to be a curative therapy for multiple myeloma. During the procedure, the patient receives chemotherapy and/or radiation treatment, which destroy the patient’s diseased stem cells as well as their healthy ones. The patient’s cells are then replaced by stem cells from a healthy donor.

However, donor stem cell transplants are associated with life-threatening side effects, such as GVHD, a condition in which immune cells from the donor attack the recipient’s cells. There are two types of GVHD. Acute GVHD occurs within 100 days of trans­plan­ta­tion and can be life-threatening.  Chronic GVHD occurs more than 100 days after trans­plan­ta­tion, which can be a good sign that the donor stem cells are also killing any remaining myeloma cells.

It is best to identify acute GVHD as early as possible to prevent serious and possibly fatal complications.  For instance, 70 percent of patients who develop mild or moderate acute GVHD can be successfully treated with steroids, whereas 80 percent to 90 percent of patients who develop severe or life-threatening acute GVHD die due to organ failure or infection.

In the current study, researchers aimed to determine if a specific set of proteins present in urine can be used to predict the development of acute GVHD in patients who underwent donor stem cell trans­plan­ta­tion.

Study Design

During the study, researchers collected urine samples from 423 blood cancer patients who underwent donor stem cell trans­plan­ta­tion between 2005 and 2010. Most patients (79 percent) were transplanted using stem cells from a matched donor; the remaining 21 percent were transplanted using stem cells from a mismatched donor. Three percent of the patients had multiple myeloma.

Patients were examined daily during hospitalization, and then weekly for the first 130 days after trans­plan­ta­tion, for signs of GVHD.

Urine samples were collected prior to trans­plan­ta­tion, on the day of trans­plan­ta­tion, and after trans­plan­ta­tion on a weekly basis until day 35 and bimonthly after day 35.

The researchers then performed a technique called proteomic profiling on the urine samples to detect levels of excreted fragments of certain proteins that play a role in GVHD.  Specifically, the researchers measured a set of 17 excreted protein fragments that indicate inflammation and activation of the immune system as early signs of organ damage caused by GVHD.

The measured levels of these protein fragments were then used to calculate the probability of a patient developing acute GVHD.  The probability, or "classification factor," as the researchers describe it, is known as aGvHD_MS17.

The researchers then used the aGvHD_MS17 values to identify patients who were, or were not, at risk of developing acute GVHD, and also to predict whether patients would develop mild or moderate GVHD,  or chronic GVHD.

Study Results

Half of the patients developed acute GVHD; 22 percent developed mild GVHD, 18 percent moderate GVHD, and 12 percent severe to life-threatening GVHD.

Among the patients with confirmed GVHD, 70 patients had biopsy results and proteome analysis available from the same time point, so the results from these patients were used for further analysis. In this group, 46 percent had mild or moderate GVHD, and 54 percent had severe or life-threatening GVHD.

The researchers found that the aGvHD_MS17 classification factor could be used to distinguish patients with no acute GVHD from those with mild, moderate, or life-threatening acute GVHD. It was also able to identify patients with GVHD that affected more than one organ; however, it was not able to specify which organs were affected.

In addition, the classification factor was able to detect GVHD at least two weeks before clinical symptoms appeared.  This allows patients to be preemptively treated for GVHD.  The study investigators state that there are currently no other methods for predicting GVHD prior to clinical symptoms.

The authors' analyses show that aGvHD_MS17 was the strongest prognostic factor for the development of severe acute GVHD. In the study, aGvHD_MS17 correctly predicted 91 percent of patients who developed severe or life-threatening acute GVHD and also correctly predicted 80 percent of patients who did not develop these more serious forms of acute GVHD. The classification factor was also able to distinguish between acute and chronic GVHD.

Other factors that increased a patient’s risk of developing acute GVHD included the genders of the recipient and donor (males transplanted with stem cells from a female were at the highest risk), patient age, con­di­tion­ing therapy, immunosuppressive antibodies, disease type, and days post-transplant.

The treatment-related death rate 100 days after trans­plan­ta­tion was 6 percent, with 1 percent dying from acute GVHD.

The study investigators state that a better understanding of the role the aGvHD_MS17 proteins play in the development of GVHD will help researchers identify new therapeutic targets for the treatment of GVHD.

For more information, please refer to the study in the journal Leukemia (abstract).