Linperlisib in the Treatment of aPRCA

Summary

Pure red cell aplasia (PRCA) is a syndrome characterized by normocytic normochromic anemia, reticulocytopenia, and reduced erythroid precursors in an otherwise normocellular bone marrow. It primarily affects erythropoiesis, while granulocytic and megakaryocytic lineages typically remain unaffected. First-line therapies for PRCA include corticosteroids (CS) and cyclosporine A（CsA). Although CS demonstrates high response rates, relapse frequently occurs upon dose reduction or discontinuation. CsA achieves response rates of 65%-87%, yet exhibits a delayed onset of action, often requiring 2-3 months to achieve transfusion independence. Sirolimus constitutes a second-line option, with additional therapeutic agents including methotrexate and cyclophosphamide. Phosphatidylinositol 3-kinases (PI3Ks) represent a family of lipid kinases. The δ and γ isoforms are predominantly expressed in leukocytes and are frequently activated in various B-cell lymphomas, serving as the primary therapeutic targets for currently approved PI3K inhibitors in hematological malignancies. PI3K also plays a critical role in modulating cells of both the adaptive and innate immune systems. Studies indicate that engagement of multiple immune receptors on leukocytes triggers PI3K activation. Consequently, isoform-selective (δ or γ) or dual δ/γ inhibitors are being investigated for autoimmune conditions such as COPD, asthma, allergies, and Sjögren's syndrome. Leniolisib, the first oral PI3Kδ inhibitor approved by the FDA for immunodeficiency, exemplifies this therapeutic strategy. Several other PI3K-targeting agents are under clinical evaluation, including Parsaclisib (Phase II trial in relapsed/refractory autoimmune hemolytic anemia) and Linperlisib (Phase I trial in relapsed/refractory AIHA). T-lymphocyte dysfunction is a pivotal factor in PRCA pathogenesis. RNA sequencing analyses have revealed significant upregulation of genes associated with the PI3K/AKT/mTOR pathway in bone marrow CD8+ T lymphocytes of patients with acquired PRCA, suggesting that targeting this pathway may represent a novel therapeutic strategy. Linperlisib, a highly selective PI3Kδ inhibitor approved for relapsed/refractory follicular lymphoma, suppresses PI3Kδ protein expression and reduces AKT phosphorylation, thereby inducing apoptosis and inhibiting lymphocyte proliferation. In 2024, a seminal report documented rapid responses and manageable tolerability with Linperlisib in four patients with acquired PRCA. Currently, no cohort studies have been conducted on Linperlisib for PRCA treatment. This study seeks to characterize the dosing regimen, efficacy, and safety profile of Linperlisib in relapsed/refractory pure red cell aplasia.

Timeline

Start

2025-09-01

Primary completion

2025-12-31

Completion

2026-12-31

Publications

• Background Means RT Jr. Pure red cell aplasia. Blood. 2016 Nov 24;128(21):2504-2509. doi: 10.1182/blood-2016-05-717140.
• Background Sawada K, Fujishima N, Hirokawa M. Acquired pure red cell aplasia: updated review of treatment. Br J Haematol. 2008 Aug;142(4):505-14. doi: 10.1111/j.1365-2141.2008.07216.x. Epub 2008 May 28.
• Background Mangla A, Hamad H. Pure Red Cell Aplasia. 2024 Feb 24. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan-. Available from http://www.ncbi.nlm.nih.gov/books/NBK549833/
• Background Clark DA, Dessypris EN, Krantz SB. Studies on pure red cell aplasia. XI. Results of immunosuppressive treatment of 37 patients. Blood. 1984 Feb;63(2):277-86.
• Background Sawada K, Hirokawa M, Fujishima N, Teramura M, Bessho M, Dan K, Tsurumi H, Nakao S, Urabe A, Omine M, Ozawa K; PRCA Collaborative Study Group. Long-term outcome of patients with acquired primary idiopathic pure red cell aplasia receiving cyclosporine A. A nationwide cohort study in Japan for the PRCA Collaborative Study Group. Haematologica. 2007 Aug;92(8):1021-8. doi: 10.3324/haematol.11192. Epub 2007 Jul 20.
• Background Liu Y, Liu M, He X, Yang L, Zhang M, Tang P, Xing L, Niu H, Wang H. Molecular landscape of CD8+ T cells in pure red cell aplasia. Ann Hematol. 2025 Feb;104(2):953-961. doi: 10.1007/s00277-025-06220-5.
• Background Fruman DA, Chiu H, Hopkins BD, Bagrodia S, Cantley LC, Abraham RT. The PI3K Pathway in Human Disease. Cell. 2017 Aug 10;170(4):605-635. doi: 10.1016/j.cell.2017.07.029.
• Background Wang Z, Jiang B, Song L, Sun M, Li C, Li X, Zheng W, Tao Y, Sun Q, Qi J. Patients with acquired pure red cell aplasia respond to PI3Kdelta inhibitor rapidly. Am J Hematol. 2024 Jul;99(7):1431-1433. doi: 10.1002/ajh.27325. Epub 2024 Apr 12. No abstract available.
• Background Red Blood Cell Disease (Anemia) Group, Chinese Society of Hematology, Chinese Medical Association. [Chinese expert consensus on the diagnosis and treatment of acquired pure red cell aplasia (2020)]. Zhonghua Xue Ye Xue Za Zhi. 2020 Mar 14;41(3):177-184. doi: 10.3760/cma.j.issn.0253-2727.2020.03.001. No abstract available. Chinese.
• Background Hirokawa M, Sawada K, Fujishima N, Teramura M, Bessho M, Dan K, Tsurumi H, Nakao S, Urabe A, Fujisawa S, Yonemura Y, Kawano F, Oshimi K, Sugimoto K, Matsuda A, Karasawa M, Arai A, Komatsu N, Harigae H, Omine M, Ozawa K, Kurokawa M; PRCA Collaborative Study Group. Long-term outcome of patients with acquired chronic pure red cell aplasia (PRCA) following immunosuppressive therapy: a final report of the nationwide cohort study in 2004/2006 by the Japan PRCA collaborative study group. Br J Haematol. 2015 Jun;169(6):879-86. doi: 10.1111/bjh.13376. Epub 2015 Mar 25.

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