Anti-thymocyte gamma-globulin may prevent antibody production after heart transplantation

Rabbit anti-thymocyte globulin (RATG) has been used as induction therapy in heart transplantation. RATG is polyclonal and has been postulated to have anti-humoral properties by preventing the production of circulating antibodies after heart transplant. Thus, we reviewed our patients who received RATG induction therapy and compared them with those who did not receive therapy for post-transplant de novo antibody production.

Between January 1, 2006, and January 1, 2013, we assessed 196 non-sensitized heart transplant recipients and divided them into those who received 3 to 5 days of RATG induction therapy mostly due to renal insufficiency (n = 35) versus patients who did not receive therapy (n = 161). All patients were given tacrolimus, mycophenolate mofetil, and corticosteroids. Post-transplant circulating antibodies were routinely monitored at 1, 3, 6, and 12 months after heart transplantation; 1-year and 3-year end points were assessed.

The RATG-treated group had a significantly higher 12-month freedom from de novo antibody production compared with the patients who did not receive RATG induction (89% vs 71%, log-rank P = .043); however there was no significant difference for 12-month freedom from de novo donor-specific antibody production (91% vs 88%, log-rank P = .541). Treated rejection rates in the first-year were comparable in both groups; 3-year actuarial survival, freedom from cardiac allograft vasculopathy, and freedom from non-fatal major adverse cardiac events were also similar between both groups.

RATG induction therapy appears to reduce the production of de novo circulating antibodies in non-sensitized patients during the first year after heart transplantation. Although there were no short-term clinical differences between groups, there were imbalances in group characteristics and relatively short follow-up, which are limitations to this study. A randomized, clinical trial with longer follow-up in a larger cohort of patients is warranted.