Introduction: TG is associated with poor allograft survival and there are limited treatment options. Some report improved outcomes with rituximab. Histopathologic scoring might predict prognosis of TG and define those who may benefit from immunomodulatory therapy.

Methods: We assessed 33 patients with biopsy proven TG. All biopsies were reviewed by the pathologist and given a glomerulitis (g) and peritubularcapillaritis (ptc) score based on the Banff 2007 criteria. We determined allograft survival in those with a g+ptc score > 4 (HiSc) and g+ptc<4 (LoSc). Creatinine (Cr) at biopsy was determined and a rise <20% over the follow-up period was considered to be stable. We assessed the impact of acute antibody mediated rejection (AMR) and rituximab (RIT) therapy on outcomes.

Results: See table below.

Mean time to diagnosis of TG was 3.2 years from date of transplant and mean follow-up after biopsy was 2.2 years. Cr and degree of proteinuria were similar in the groups at the time of biopsy. 23/33 (70%) patients received RIT in combination with IVIG as part of their therapeutic regimen. Among the 10 who did not receive RIT, 1 got IVIG only, 6 got pulse steroids only, and 3 had no therapy.

Those who receieved RIT were more likely to have Cr stabilization (43% v. 20%, p=0.02). They also tended to have have a decrease in the strength of their DSA. RIT did not have an effect on Cr stabilization in the LoSc group, but did in the HiSc group (0% v. 45%. p=0.01).

We compared graft survival in those with TG to a cohort with AMR and no evidence of TG. Graft survival was 61% in those with TG and 70% in those with AMR (no TG)(p=NS).

Conclusion: g+ptc ≥4 in patients with TG had unexpectedly better outcomes with Cr stabilization. Overall, RIT tended to improve DSA and stabilize Cr. However the LoSc group did not seem to benefit from this. Higher histopathologic scores with g+ptc≥4 in patients with TG have improved outcomes and may benefit from RIT.

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