Luspatercept

Luspatercept is a recombinant fusion protein and an erythroid maturation agent used to treat certain forms of anaemia, a condition in which the body has insufficient healthy red blood cells or haemoglobin to carry oxygen effectively. It works by regulating selected transforming growth factor beta superfamily signalling pathways involved in red blood cell development. By reducing inhibitory signals that interfere with late-stage red blood cell maturation, luspatercept helps the bone marrow produce mature red blood cells more effectively. It is used in adults with selected forms of beta-thalassaemia and myelodysplastic syndromes (MDS), depending on the approved indication and treatment history. Luspatercept is administered as a subcutaneous injection, meaning it is injected under the skin, usually at intervals of three weeks. In eligible patients, treatment can reduce the need for regular red blood cell transfusions or improve anaemia management. It does not replace transfusions when immediate correction of severe anaemia is required. Treatment decisions depend on the underlying disorder, transfusion requirements, previous therapies, blood counts, and individual risk factors. Blood pressure, haemoglobin levels, and symptoms suggesting complications must be monitored during therapy. Luspatercept should be prescribed and supervised by a qualified healthcare professional experienced in managing haematological disorders.

Luspatercept was developed as a targeted treatment to improve red blood cell maturation by regulating signalling pathways that inhibit erythropoiesis, the process through which red blood cells develop. Its development focused on anaemia associated with beta-thalassaemia and lower-risk myelodysplastic syndromes. In the United States, the US Food and Drug Administration (FDA) first approved luspatercept in November 2019 for anaemia in adults with beta-thalassaemia requiring regular red blood cell transfusions. In April 2020, the FDA approved it for selected adults with lower-risk myelodysplastic syndromes with ring sideroblasts or related myelodysplastic/myeloproliferative neoplasms after an inadequate response to erythropoiesis-stimulating agents. An additional FDA indication for certain adults with lower-risk MDS who had not previously received erythropoiesis-stimulating agents was approved in August 2023. The European Medicines Agency (EMA) granted marketing authorisation in the European Union on 25 June 2020, with subsequent updates to the authorised indications. Important clinical programmes included the BELIEVE trial in beta-thalassaemia, the MEDALIST trial in previously treated MDS with ring sideroblasts, and the COMMANDS trial in previously untreated, lower-risk MDS. Regulatory indications and prescribing requirements may vary by country.

Luspatercept is used in adults with specific forms of anaemia associated with beta-thalassaemia and myelodysplastic syndromes. In beta-thalassaemia, it is indicated in eligible patients who require regular red blood cell transfusions to manage anaemia. In myelodysplastic syndromes, it may be used in adults with very low- to intermediate-risk disease who have not previously received an erythropoiesis-stimulating agent and may require regular transfusions. It is also indicated for selected adults with very low- to intermediate-risk MDS with ring sideroblasts, or myelodysplastic/myeloproliferative neoplasm with ring sideroblasts and thrombocytosis, when anaemia has not responded adequately to an erythropoiesis-stimulating agent and transfusion requirements meet the relevant prescribing criteria. The choice of treatment depends on the diagnosis, disease risk category, transfusion history, previous therapies, and applicable local approval. Luspatercept is not intended to replace red blood cell transfusions when immediate correction of anaemia is necessary.

Luspatercept is administered by subcutaneous injection, generally once every three weeks. The usual starting dose for adults is 1 mg/kg, calculated using body weight, with subsequent adjustments based on the indication, haemoglobin response, transfusion requirements, tolerability, and the applicable prescribing information. For beta-thalassaemia, the dose may be increased gradually up to 1.25 mg/kg if the response is insufficient and treatment remains appropriate. For myelodysplastic syndromes, the approved maximum dose may reach 1.75 mg/kg, depending on the specific indication and treatment response. Haemoglobin results should be reviewed before each dose, and treatment may need to be delayed or adjusted if haemoglobin rises excessively or other safety concerns develop. Treatment duration depends on clinical response, ongoing benefit, and tolerability. It may be discontinued if the patient does not achieve a meaningful response after an appropriate treatment period or develops unacceptable toxicity. Luspatercept must be prepared and administered by trained healthcare professionals according to the applicable product instructions.

Common side effects of luspatercept include fatigue, headache, dizziness, joint pain, muscle or bone pain, nausea, diarrhoea, cough, abdominal discomfort, shortness of breath, swelling of the extremities, and increased blood pressure. Some patients may experience hypersensitivity reactions or other injection-related symptoms. The type and severity of side effects vary according to the underlying disease, individual health status, and treatment response. Many adverse effects can be managed through clinical assessment, supportive care, and appropriate monitoring. Patients should report persistent, worsening, or unusual symptoms to their treating healthcare professional rather than changing or stopping treatment independently.

Important risks associated with luspatercept include hypertension, thromboembolic events such as deep vein thrombosis or pulmonary embolism, and extramedullary haematopoietic masses, particularly in patients with beta-thalassaemia. These complications require clinical assessment and prompt management. Luspatercept may also cause fetal harm, so pregnancy must be avoided during treatment and for the recommended period after the final dose according to the applicable prescribing guidance. Treatment may need to be withheld, adjusted, or discontinued if serious complications occur, if haemoglobin rises beyond recommended levels, or if the patient experiences an unacceptable adverse reaction. Luspatercept is not a substitute for urgent red blood cell transfusion in patients who need immediate correction of anaemia. The US prescribing information does not list formal contraindications, but treatment still requires careful assessment of individual risks and benefits.

Before starting luspatercept, healthcare professionals should assess the underlying haematological condition, haemoglobin levels, transfusion history, blood pressure, and relevant medical history. Patients with beta-thalassaemia should be evaluated for risk factors associated with thromboembolism and extramedullary haematopoiesis. Blood pressure should be monitored throughout treatment, and pre-existing hypertension should be appropriately managed. Luspatercept may cause fetal harm; patients who could become pregnant should receive counselling about effective contraception during treatment and for at least three months after the final dose, according to US prescribing information. Breastfeeding is generally not recommended during treatment. Patients should inform their healthcare professional about all medicines, supplements, and ongoing therapies. Luspatercept is a biologic fusion protein rather than a conventional small-molecule drug, and classic metabolic drug interactions are not expected to be its primary interaction concern. Nevertheless, concomitant treatment and other medical conditions should be reviewed individually.

Confirm that the patient meets the approved indication and that the anaemia is associated with the relevant underlying disorder before initiating luspatercept. Document baseline haemoglobin levels, transfusion burden, blood pressure, prior erythropoiesis-stimulating agent use where relevant, and risk factors for thrombosis. Review haemoglobin results before every administration and follow the indication-specific dose escalation, interruption, and discontinuation criteria. Monitor for new or worsening hypertension, symptoms of venous or arterial thrombosis, and signs of extramedullary haematopoietic masses in patients with beta-thalassaemia. Counsel patients that clinical improvement may take time and that transfusions should continue when medically necessary. Pregnancy prevention, breastfeeding advice, and potential fetal risks should be discussed before treatment. Pharmacists and administration staff should follow the product-specific instructions for reconstitution, storage, handling, and subcutaneous injection. Coordinate care with the treating haematologist and transfusion service to evaluate treatment response, manage adverse events, and determine whether continued therapy provides meaningful clinical benefit.