Efficacy and Safety of Biosimilar Romiplostim in Immune Thrombocytopenic Purpura : Single Centre Retrospective Data Analysis

Introduction: Thrombopoietin receptor agonist (TPO RA) is an approved second line of treatment in Persistent and Chronic Immune Thrombocytopenic Purpura (ITP).However in India due to cost constraints, the majority prefer Immunosuppression therapy. A biosimilar of Romiplostim (Romy®) is developed and launched in India, by Intas Pharmaceuticals, India, in July 2019, its monthly cost is around $160, a huge relief to ITP patients (pts), now accessible to the masses in Lower Middle Income Country (LMIC), India. Real-world experience data on Romiplostim (Romy®) in ITP is sparse.

Aim: A single centre retrospective data analysis to evaluate the Safety and Efficacy of Biosimilar Romiplostim (Romy®) in patients of Immune Thrombocytopenic Purpura.

Method: A total of 54 steroid-refractory or steroid-dependent ITP pts were registered at Haemato-oncology Care Centre Vadodara from July 2019 to January 2020, who received Injection Romiplostim (Romy®) treatment. Pre-treatment Complete Blood Count( CBC) Platelet count (PLT) ,Liver Function Test ,Renal Function Tests ,PT,PTT,ANA,HIV,HBsAg,HCV,Bone Marrow,USG Abdomen, Chest X-Ray was done.All patients had pretreatment Platelet count less than 30000/cumm.The dose of Romiplostim was 1mcg /kg to 6 mcg/kg, subcutaneous once a week.12 /54 patients who had active bleeding also received concomitant Rituximab 100mg IV infusion once a week for 4 weeks. The response was assessed by CBC PLT every week for the first 4 weeks, later on, every monthly. The response was labelled as Optimum if PLT count maintained between 50000/cumm to 4,00,000/cumm, Suboptimal if PLT count increased from baseline but remained below 50,000/cumm, No response if no increment from baseline PLT count. Romiplostim was continued with the same dose if response was Optimum, escalated if response was Suboptimal, de-escalated if PLT increased above 1, 50,000/cumm and stopped if PLT increased above 4,00,000/cumm or no response found after 4 weeks of treatment.

Results: A total of 54 pts were evaluated, 23(42%) Male, 31(58%) Female, Median age 40 years (range 8 yrs to 85yrs).Persistent ITP was the diagnosis in 38/54(70%)pts, Chronic ITP in 16/54(30%) pts, Secondary ITP in 17(30%) pts, with 14 patients had ANA positive, 2 patients had HCV positive, 1 patient had tubercular lymphadenopathy. The overall response rate (ORR) was 50/54(93%).Optimum response in 49 /54 (91%),Suboptimal response in 1/54 (2%),No response in 4/54(7%)pts. ORR in patients who received Rituximab with Romiplostim was 12/12 (100%). Time to achieve response was 1 week in 46 (85%) pts, 2 weeks in 3(5%) pts, and 3 weeks in 1 (2%) pts. Follow up assessment showed a total of 21/54 (40%) patients had sustained optimum response for more than 6 months with continuation of once a week Romiplostim,9/54 (16%) had sustained response for more than 6 months even on discontinuation of Romiplostim after 4 weeks.8/54(15%) pts with ANA positive reports required a combination of immunosuppressant with Romiplostim to maintain prolonged sustained response.4/54(7%) pts did not respond to Romiplostim hence it was stopped after 4 weeks. Mild adverse effects were observed headache 5(9%), myalgia 3 (5%), bone pains 6(11) Abdominal pain 4(7%) pts. Romiplostim was stopped in 12 (22%) pts because of thrombocytosis (PLT above 4, 50,000/cumm) after a first single dose of Romiplostim. None of the patients had serious adverse events

Conclusion: Biosimilar Romiplostim, (Romy®) has shown rapid, excellent and sustained response in the majority of ITP pts in our study. Its affordable cost fulfils an unmet need of ITP patients, requiring the best second line of treatment in LMIC