Written by: Dr. M. Yair Levy, Texas Oncology
Promotional Content Sponsored by: Bristol Myers Squibb
Dr. Levy is a paid consultant for BMS and was compensated for his contribution in drafting this article.
Myelodysplastic syndromes (MDS) are a heterogeneous group of myeloid malignancies characterized by multilineage cytopenias, including anemia.1 In MDS, stem cells lack the ability for differentiation and maturation, resulting in bone marrow dysfunction and poor blood cell production, in particular red blood cells (RBCs).2 Anemia is present in the majority of patients with MDS and, at diagnosis, anemia is the most common cytopenia present in patients with MDS.1 Anemia in MDS is linked to bone marrow dysfunction characterized by ineffective erythropoiesis.2
Ineffective erythropoiesis in MDS may lead to anemia requiring RBC transfusions and is characterized by increased proliferation of erythroid progenitors, increased death of erythroid precursors, and impaired erythroid maturation.3,4 In fact, 94% (515/546) of patients with MDS received RBC transfusions in the SEER-Sound registry from 2001 to 2007, 13% of whom had ring sideroblasts.5 Ring sideroblasts are erythroblasts with iron-loaded mitochondria associated with anemia that can be identified by iron staining and the results can be found on pathology reports.6
The presence of anemia despite increased proliferation of progenitor cells is indicative of ineffective erythropoiesis in MDS.3,4 There is a need to help address anemia due to ineffective erythropoiesis in patients with MDS requiring RBC transfusions after erythropoiesis stimulating agent (ESA) failure. REBLOZYL® (luspatercept-aamt), the first and only erythroid maturation agent, is approved for the treatment of anemia failing an ESA and requiring 2 or more RBC units over 8 weeks in adult patients with very low- to intermediate-risk myelodysplastic syndromes with ring sideroblasts (MDS-RS) or with myelodysplastic/myeloproliferative neoplasm with ring sideroblasts and thrombocytosis (MDS/MPN-RS-T).7 REBLOZYL is not indicated for use as a substitute for RBC transfusions in patients who require immediate correction of anemia.7 The approval of REBLOZYL by the FDA marked the first new treatment indicated for patients with MDS in 14 years.8 In my clinical experience, the results that I’ve seen in patients with lower-risk MDS-RS are consistent with those seen in the MEDALIST clinical trial, as discussed below.
As the first and only erythroid maturation agent, REBLOZYL enhances erythroid maturation through differentiation of late-stage erythroid precursors. REBLOZYL works by binding several TGF-β superfamily ligands, thereby diminishing Smad2/3 signaling and increasing the number and quality of mature RBCs in preclinical models.7
REBLOZYL was FDA approved for MDS-associated anemia based on the efficacy and safety outcomes of the pivotal phase 3 MEDALIST trial.7,9 The MEDALIST trial was a multicenter, randomized, double-blind, placebo-controlled, phase 3 trial of 229 adult patients with IPSS-R very low-, low-, or intermediate-risk MDS-RS (<5% bone marrow blasts, presence of ring sideroblasts of ≥15% or ≥5% with an SF3B1 mutation) who required RBC transfusions (≥2 RBC units/8 weeks) were randomized 2:1 to REBLOZYL (n = 153) or placebo (n = 76).7,9 Patients were also required to have had an inadequate response to prior treatment with an ESA (defined as response that is no longer maintained after at least 8 doses of recombinant human erythropoietin or 4 doses of darbepoetin alfa), be intolerant of ESAs, or be ineligible for ESAs (serum EPO >200 U/L).7,9 The MEDALIST trial excluded patients who had del 5q MDS, a white blood cell count >13 Gi/L, neutrophils <0.5 Gi/L, platelets <50 Gi/L, or who had prior use of a disease-modifying agent for treatment of MDS.7
REBLOZYL was administered 1 mg/kg subcutaneously every 3 weeks for at least 24 weeks or until unacceptable toxicity, loss of efficacy, or disease progression. Patients could have their dose increased to 1.33 mg/kg and then to 1.75 mg/kg. Patients received dose increases if they did not achieve transfusion independence after two doses or 6 weeks at 1 mg/kg and 1.33 mg/kg. All patients received best supportive care, which included RBC transfusions as needed.7
In MEDALIST, 36% (83/229) of all patients in the trial were 75 years of age or older, including patients up to 95 years.7,9 95.2% (218/229) of all patients in the trial were ESA-exposed, while only 4.8% (11/229) were ESA-naive, with serum EPO >200 U/L.7,9 All patients in the trial had ring sideroblasts (≥15% ring sideroblasts or ≥5% ring sideroblasts with an SF3B1 mutation), and the majority (206/229) had an SF3B1 mutation.7,9 All patients except 1 were classified as having very low- to intermediate-risk MDS by the IPSS-R criteria.7 57% (130/229) of patients had a baseline RBC transfusion burden <6 RBC units/8 weeks.7
The primary endpoint in MEDALIST was RBC transfusion independence (RBC-TI), defined as the absence of any RBC transfusion during any consecutive 8-week period occurring entirely within the first 24 weeks of treatment.7 Approximately 3 times greater percentage of patients receiving REBLOZYL achieved the primary endpoint of RBC transfusion independence than placebo: 37.9% (58/153) vs 13.2% (10/76; common risk difference [95% CI]: 24.6 [14.5, 34.6]; P < 0.0001), respectively.7 These data support that in patients requiring ≥2 RBC units/8 weeks, REBLOZYL should be started after at least 2 to 3 months of an inadequate response to ESAs.7,9
Key secondary endpoints in MEDALIST were based on RBC transfusion independence (absence of any RBC transfusions) during any consecutive 12-week period occurring entirely within weeks 1 to 24 and 1 to 48. 28.1% (43/153) of patients receiving REBLOZYL achieved transfusion independence ≥12 weeks occurring entirely within weeks 1 to 24 vs 7.9% (6/76) of patients receiving placebo (common risk difference [95% CI]: 20.0 [10.9, 29.1]; P = 0.0002). For weeks 1 to 48,* 33.3% (51/153) of patients receiving REBLOZYL achieved transfusion independence ≥12 weeks vs 11.8% (9/76) of patients receiving placebo (common risk difference [95% CI]: 21.4 [11.2, 31.5]; P = 0.0003).7
*The median (range) duration of treatment was 49 weeks (6–114 weeks) on the REBLOZYL arm and 24 weeks (7-89 weeks) on the placebo arm.
REBLOZYL provided RBC transfusion independence vs placebo in patients with MDS-RS and MDS/MPN-RS-T, based on the WHO 2016 classification. Of patients who were diagnosed with MDS-RS, 34.1% (46/135; 95% CI 26.1, 42.7) of patients receiving REBLOZYL achieved transfusion independence vs 12.3% (8/65; 95% CI 5.5, 22.8) receiving placebo. Of patients who were diagnosed with MDS/MPN-RS-T, 64.3% (9/14; 95% CI 35.1, 87.2) of patients receiving REBLOZYL achieved transfusion independence vs 22.2% (2/9; 95% CI 2.8, 60.0) receiving placebo. Of patients who were diagnosed with other types of MDS (MDS-EB-1, MDS-EB-2, and MDS-U), 75% (3/4; 95% CI 19.4, 99.4) of patients receiving REBLOZYL achieved transfusion independence vs 0% (0/2; 95% CI 0.0, 84.2) receiving placebo.7
RBC transfusion independence was also examined by baseline RBC transfusion burden. Of patients requiring 2 to 3 RBC units/8 weeks at baseline,† 80.4% (37/46; 95% CI 66.1, 90.6) of patients receiving REBLOZYL achieved transfusion independence vs 40% (8/20; 95% CI 19.1, 63.9) receiving placebo. Of patients requiring 4 to 5 RBC units/8 weeks at baseline,‡ 36.6% (15/41; 95% CI 22.1, 53.1) of patients receiving REBLOZYL achieved transfusion independence vs 4.3% (1/23; 95% CI 0.1, 21.9) receiving placebo. Of patients requiring ≥6 RBC units/8 weeks, 9.1% (6/66; 95% CI 3.4, 18.7) of patients receiving REBLOZYL achieved transfusion independence vs 3% (1/33; 95% CI 0.1, 15.8) receiving placebo.7
†Includes patients who received 3.5 units.
‡Includes patients who received 5.5 units.
The safety of REBLOZYL at the recommended dose and schedule was evaluated in 242 patients with MDS-RS (n = 192) or other myeloid neoplasms (n = 50). The median time on treatment with REBLOZYL was 50.4 weeks (range, 3-221 weeks), with 67% of patients exposed for 6 months or longer and 49% exposed for >1 year.7
Among the 242 patients treated with REBLOZYL, 5 (2.1%) had a fatal adverse reaction. 4.5% (11/242) of patients discontinued REBLOZYL due to an adverse reaction and 2.9% (7/242) of patients had their REBLOZYL dose reduced due to adverse reactions. The most common (≥10%) all-grade adverse reactions included fatigue, musculoskeletal pain, dizziness, diarrhea, nausea, hypersensitivity reactions, hypertension, headache, upper respiratory tract infection, bronchitis, and urinary tract infection. The majority of adverse reactions with REBLOZYL were Grade 1 or 2 (mild to moderate). The most common (≥2%) Grade ≥3 adverse reactions included fatigue, hypertension, syncope, and musculoskeletal pain.7
IMPORTANT SAFETY INFORMATION
WARNINGS AND PRECAUTIONS
In adult patients with beta thalassemia, thromboembolic events (TEE) were reported in 8/223 (3.6%) REBLOZYL-treated patients. TEEs included deep vein thrombosis, pulmonary embolus, portal vein thrombosis, and ischemic stroke. Patients with known risk factors for thromboembolism (splenectomy or concomitant use of hormone replacement therapy) may be at further increased risk of thromboembolic conditions. Consider thromboprophylaxis in patients at increased risk of TEE. Monitor patients for signs and symptoms of thromboembolic events and institute treatment promptly.
Hypertension was reported in 10.7% (61/571) of REBLOZYL-treated patients. Across clinical studies, the incidence of Grade 3 to 4 hypertension ranged from 1.8% to 8.6%. In adult patients with MDS with normal baseline blood pressure, 26 (29.9%) patients developed SBP ≥130 mm Hg and 23 (16.4%) patients developed DBP ≥80 mm Hg. Monitor blood pressure prior to each administration. Manage new or exacerbations of preexisting hypertension using anti-hypertensive agents.
REBLOZYL may cause fetal harm when administered to a pregnant woman. REBLOZYL caused increased post-implantation loss, decreased litter size, and an increased incidence of skeletal variations in pregnant rat and rabbit studies. Advise pregnant women of the potential risk to a fetus. Advise females of reproductive potential to use effective contraception during treatment and for at least 3 months after the final dose.
Grade ≥3 (≥2%) adverse reactions included fatigue, hypertension, syncope and musculoskeletal pain. A fatal adverse reaction occurred in 5 (2.1%) patients.
The most common (≥10%) adverse reactions included fatigue, musculoskeletal pain, dizziness, diarrhea, nausea, hypersensitivity reactions, hypertension, headache, upper respiratory tract infection, bronchitis, and urinary tract infection
It is not known whether REBLOZYL is excreted into human milk or absorbed systemically after ingestion by a nursing infant. REBLOZYL was detected in milk of lactating rats. When a drug is present in animal milk, it is likely that the drug will be present in human milk. Because many drugs are excreted in human milk, and because of the unknown effects of REBLOZYL in infants, a decision should be made whether to discontinue nursing or to discontinue treatment. Because of the potential for serious adverse reactions in the breastfed child, breastfeeding is not recommended during treatment and for 3 months after the last dose.
Please see full Prescribing Information for REBLOZYL
1. Greenberg PL, Tuechler H, Schanz J, et al. Revised international prognostic scoring system for myelodysplastic syndromes. Blood. 2012;120(12):2454-2465.
2. Cazzola M, Malcovati L. Myelodysplastic syndromes—coping with ineffective hematopoiesis. N Engl J Med. 2005;352(6):536-538.
3. Santini V. Anemia as the main manifestation of myelodysplastic syndromes. Semin Hematol. 2015;52(4):348-356.
4. Fontenay-Roupie M, Bouscary D, Guesnu M, et al. Ineffective erythropoiesis in myelodysplastic syndromes: correlation with Fas expression but not with lack of erythropoietin receptor signal transduction. Br J Haematol. 1999;106(2):464-473.
5. Ramsey SD, McCune JS, Blough DK, et al. Patterns of blood product use among patients with myelodysplastic syndrome. Vox Sang. 2012;102(4):331-337.
6. Malcovati L, Cazzola M. Recent advances in the understanding of myelodysplastic syndromes with ring sideroblasts. Br J Haematol. 2016;174(6):847-858.
7. REBLOZYL [Prescribing Information]. Summit, NJ: Celgene Corporation; 2020.
8. Steensma, D.P. Myelodysplastic syndromes current treatment algorithm 2018. Blood Cancer J. 2018;8(5):47.
9. Data on file, Celgene Corporation. Summit, New Jersey.
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REBLOZYL is a trademark of Celgene Corporation, a Bristol Myers Squibb company.
REBLOZYL is licensed from Acceleron Pharma Inc.