On December 4, 2016 Acceleron Pharma Inc. (NASDAQ:XLRN) and Celgene Corporation (NASDAQ:CELG), reported preliminary Phase 2 results from the ongoing three-month base and long-term extension studies with investigational drug luspatercept in patients with lower risk myelodysplastic syndromes (MDS) at the 58th Annual Meeting of the American Society of Hematology (ASH) (Free ASH Whitepaper) in San Diego, California (Press release, Acceleron Pharma, DEC 4, 2016, View Source [SID1234516906]). Luspatercept is being developed as part of the global collaboration between Acceleron and Celgene.

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"We are encouraged by the additional luspatercept data from the ongoing Phase 2 studies," said Michael Pehl, President, Hematology and Oncology for Celgene. "These data further support luspatercept’s potential in treating a broader spectrum of MDS patients. We are evaluating opportunities to expand our clinical program to include additional MDS patient populations, as we advance our Phase 3 MEDALIST trial in RS+ patients."

Luspatercept Phase 2 Data in First-line, ESA treatment-naive MDS Patients

In lower-risk MDS patients who have not received prior treatment with an erythropoiesis-stimulating agent (ESA) and have erythropoietin (EPO) levels ≤ 500 IU, luspatercept three-month base study data demonstrated encouraging rates of transfusion independence and International Working Group Hematologic Improvement – Erythroid (IWG HI-E) response criteria.

Transfusion Burden IWG HI-E, n/N (%) RBC-TI, n/N (%)
Base N=64 Extension N=42 Base N=49 Extension N=28
All 12/20 (60%) 13/16 (81%) 9/12 (75%) 8/10 (80%)
Low Transfusion Burden 6/13 (46%) 8/11 (73%) 5/5 (100%) 5/5 (100%)
High Transfusion Burden 6/7 (86%) 5/5 (100%) 4/7 (57%) 3/5 (60%)

Luspatercept Phase 2 Data in Ring Sideroblast Positive (RS+) and Negative (RS-) in MDS Patients

In patients with EPO levels < 200, response rates were similar in both RS+ and RS- patients
In the patients with EPO levels ≥ 200 to ≤ 500, luspatercept response rates remained encouraging in those patients who are RS+

Baseline EPO
(U/L)

RS
Status
IWG HI-E, n/N (%) RBC-TI, n/N (%)

Base
N=64*

Extension
N=42*

Base
N=49*

Extension
N=28*

< 200 RS+ 18/29 (62%) 19/23 (83%) 13/19 (68%) 10/14 (71%)
RS- 2/5 (40%) 3/3 (100%) 1/4 (25%) 1/2 (50%)
≥ 200 to ≤ 500 RS+ 5/11 (46%) 7/8 (88%) 3/9 (33%) 3/5 (60%)
RS- 0/3 (0%) 0/1 (0%) 2/2 (100%) 1/1 (100%)
*Table includes both ESA refractory and ESA naïve patients. Subjects treated at dose levels ≥ 0.75 mg/kg.

Luspatercept Phase 2 Safety Data

The majority of adverse events (AEs) were grade 1 or 2
There were four grade 3/serious AEs possibly or probably related to study drug as of November 28, 2016: blast cell count increase, myalgia, worsening of general condition, progression to AML
Adverse events at least possibly related to study drug that occurred in at least 2 patients during studies were diarrhea, fatigue, headache, hypertension, arthralgia, bone pain, injection site erythema, myalgia and peripheral edema.
Luspatercept is an investigational product that is not approved for use in any country.

The MEDALIST Trial, a global Phase 3 study in patients with very low, low, or intermediate risk, MDS with ring sideroblasts who require red blood cell transfusions, is currently enrolling.

The poster presentation of the ongoing Phase 2 studies is available on Acceleron’s website (www.acceleronpharma.com) under the Science tab.