Safety and efficacy of azathioprine in immune thrombocytopenia

Immune thrombocytopenia (ITP) is a benign hematological disorder characterized by low platelet counts in peripheral blood and spectrum of various bleeding manifestations. Azathioprine is one of the effective, readily available, and affordable immunosupressants available for ITP management in developing countries. We aimed to study the efficacy and long-term safety profile of our patients with ITP who were treated with azathioprine.

This was a retrospective, single-center study conducted at a tertiary care hospital in Northern India. The patients who had received at least one line of therapy before receiving azathioprine were included in this study. All patients received oral azathioprine at a dose of 1 mg/kg/day (50 mg or 100 mg tablet formulations were used), which was increased up to 2 mg/kg/day depending upon the response and adverse effects.

Sixty-three patients were analyzed. Their median age was 28 years (range 15-68); 29/63 patients (46.03%) were females. The median duration from diagnosis to azathioprine initiation was 539 days (323 days-980.5 days). The patients included in the study had received a median of 3 (range 1-6) prior lines of therapies; 38/63 patients (60.32%) had received ≥3 prior therapies. Six patients (9.5%) had relapsed after splenectomy, and 16 patients (25.4%) had relapsed after receiving rituximab. The mean baseline platelet count was 10000/μL. The median time to response was 95 days (90 days-not reached) and the cumulative overall response rate (complete and partial response) at day 90 was 38.1%. Only one patient achieved complete response with azathioprine in our study. The cumulative rate of relapse at five years was 21.2%. Twenty-six patients stopped azathioprine after achieving some response (CR/PR) with Azathioprine for a median duration of 1067.5 days (range: 236 days-2465 days). They were followed up for a median of 870 days (range: 392 days-1928 days), and twelve of them relapsed. Twenty-six patients (26/63, 41.27%) reported one or more adverse events while on azathioprine. Leucopenia was the most frequent adverse event, followed by anemia and hepatobiliary laboratory abnormalities. Serious adverse events (grade ≥3 CTCAEv4) were noted in three patients (4.7%). One patient succumbed to severe sepsis multiorgan dysfunction while being on treatment.

We conclude that azathioprine has a good response rate in chronic ITP patients. It is well-tolerated with minimal and manageable side effects.