SYNBIoSe-1 results at odds with CALIBRATE trial results
The favorable impact of the rituximab/belimumab combo on lupus nephritis seen in SYNBIoSe-1 is at odds with the results of CALIBRATE, a U.S. study in which 43 patients with active lupus nephritis despite conventional treatment were randomized open label to induction therapy with two doses of rituximab on top of standard background therapy, followed by either belimumab and prednisone or prednisone alone. In CALIBRATE, the anti-BLyS biologic didn’t improve clinical outcomes. Dr. Teng said he believes he knows why.
“There was an important difference in background immunosuppression in the two studies. We used mycophenolate in SYNBIoSe-1, while they used cyclophosphamide in CALIBRATE,” he noted. “Other investigators have shown that mycophenolate mostly depletes plasma cells, whereas cyclophosphamide is very much depleting proliferating cells, predominantly the B-cell population and to a lesser extent the plasma cell population. I think this phenomenon might explain why adding BLyS inhibition to patients treated with CellCept [mycophenolate] might be of more added value than adding it to cyclophosphamide therapy.”
Dr. Teng reported having no financial conflicts regarding the SYNBIoSe-1 study, which was funded by research grants from the Dutch Kidney Foundation and the Netherlands Organization for Health Research and Development.