Long-Term Efficacy and Safety of Luspatercept for Anemia Treatment in Patients With Lower-Risk Myelodysplastic Syndromes: The Phase II PACE-MDS Study.

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.Luspatercept has high clinical activity in patients with transfusion-dependent lower-risk myelodysplastic syndromes (LR-MDS) and ring sideroblasts (RS) relapsed or refractory to erythropoietin. We report long-term luspatercept safety and efficacy in 108 patients with LR-MDS in the PACE-MDS study, including 44 non-RS and 34 non-transfusion-dependent or previously untreated patients. The primary end point was safety. Secondary end points included rates of hematologic improvement (HI) erythroid (HI-E), HI neutrophil, and HI platelet. Exploratory end points included erythropoiesis biomarker quantitation and mutation data. Median duration of luspatercept exposure was 315 days (range, 21-1,934 days). No new safety signals emerged. HI-E was observed in 53.7% of patients, including 36.4% of non-RS and 70.6% of non-transfusion-dependent patients. HI neutrophil and HI platelet were observed in 33.3% and 9.5% of patients, respectively. An almost three-fold increase in bone marrow late to early progenitor cell ratio accompanied HI-E response, irrespective of RS status. Lower baseline erythropoietin levels in non-RS patients (69.6 v 623.3 IU/L; P = .0077) and higher late to early erythroid progenitor cell ratio (10.44 v 4.48; P = .0106) in RS patients were associated with HI-E. This study highlights luspatercept's effects across LR-MDS subtypes, including untreated MDS-RS, serving as a platform for future trials.

Sotatercept with long-term extension for the treatment of anaemia in patients with lower-risk myelodysplastic syndromes: a phase 2, dose-ranging trial.

BACKGROUND: Myelodysplastic syndromes are characterised by ineffective erythropoiesis leading to anaemia. Sotatercept (ACE-011) is a novel activin receptor type IIA fusion protein that acts as a ligand trap to neutralise negative regulators of late-stage erythropoiesis. The aim of the study was to establish a safe and effective dose of sotatercept for the treatment of anaemia in patients with lower-risk myelodysplastic syndromes. METHODS: This open-label, multicentre, dose-ranging, phase 2 trial took place at 11 treatment centres in the USA and France. Eligible patients were aged 18 years or older, had International Prognostic Scoring System-defined low-risk or intermediate-1-risk myelodysplastic syndromes, had anaemia requiring red blood cell (RBC) transfusions, and were ineligible for, or refractory to, erythropoiesis-stimulating agents (ESAs). Patients were not eligible if they had chromosome 5q deletion myelodysplastic syndromes without documented failure of lenalidomide. Patients were randomly assigned to receive either 0·1 or 0·3 mg/kg sotatercept subcutaneously, using a permuted-block method with stratification for serum erythropoietin concentration and transfusion burden. Patients were assigned to 0·5, 1·0, and 2·0 mg/kg groups in a non-randomised fashion. The primary efficacy endpoint was the proportion of patients who achieved haematological improvement-erythroid (HI-E), according to International Working Group 2006 criteria. Efficacy and safety analyses were done in the intention-to-treat population. This trial is registered at ClinicalTrials.gov, number NCT01736683 and at EU Clinical Trials Register, number 2012-002601-22, and is ongoing. FINDINGS: Between Dec 5, 2012, and July 22, 2015, 74 patients were enrolled into the study (seven to receive 0·1 mg/kg sotatercept, six to 0·3 mg/kg, 21 to 0·5 mg/kg, 35 to 1·0 mg/kg, and five to 2·0 mg/kg). 36 (49%; 95% CI 38-60) of 74 patients achieved HI-E; 29 (47%; 95% CI 35-59) of 62 patients with a high transfusion burden achieved HI-E (RBC-transfusion reduction from baseline of 4 or more units for at least 56 days), and seven (58%; 95% CI 32-81) of 12 patients with a low transfusion burden achieved HI-E (haemoglobin increase of 1·5 g/dL or more sustained for at least 56 days in the absence of transfusions). The most commonly reported adverse events were fatigue in 19 (26%) of 74 patients and peripheral oedema in 18 (24%) of 74 patients. Grade 3-4 treatment-emergent adverse events (TEAEs) were reported in 25 (34%) of 74 patients; four (5%) patients had grade 3-4 TEAEs that were considered to be treatment related. The most common grade 3-4 TEAEs were lipase increase and anaemia, which each occurred in three (4%) of 74 patients. 17 (23%) of 74 patients had at least one serious TEAE, and one patient died from a treatment-emergent subdural haematoma due to a fall. INTERPRETATION: Sotatercept, a novel activin-receptor fusion protein, was well tolerated and effective for the treatment of anaemia in patients with lower-risk myelodysplastic syndromes in whom previous ESA treatment had failed. Treatment with sotatercept could be beneficial for these patients who have few available treatment options. FUNDING: Celgene Corporation.

Luspatercept for the treatment of anaemia in patients with lower-risk myelodysplastic syndromes (PACE-MDS): a multicentre, open-label phase 2 dose-finding study with long-term extension study.

BACKGROUND: Myelodysplastic syndromes are characterised by ineffective erythropoiesis. Luspatercept (ACE-536) is a novel fusion protein that blocks transforming growth factor beta (TGF ß) superfamily inhibitors of erythropoiesis, giving rise to a promising new investigative therapy. We aimed to assess the safety and efficacy of luspatercept in patients with anaemia due to lower-risk myelodysplastic syndromes. METHODS: In this phase 2, multicentre, open-label, dose-finding study (PACE-MDS), with long-term extension, eligible patients were aged 18 years or older, had International Prognostic Scoring System-defined low or intermediate 1 risk myelodysplastic syndromes or non-proliferative chronic myelomonocytic leukaemia (white blood cell count <13 000/µL), and had anaemia with or without red blood cell transfusion support. Enrolled patients were classified as having low transfusion burden, defined as requiring less than 4 red blood cell units in the 8 weeks before treatment (and baseline haemoglobin <10 g/dL), or high transfusion burden, defined as requiring 4 or more red blood cell units in the 8 weeks before treatment. Patients received luspatercept subcutaneously once every 21 days at dose concentrations ranging from 0·125 mg/kg to 1·75 mg/kg bodyweight for five doses (over a maximum of 12 weeks). Patients in the expansion cohort were treated with 1·0 mg/kg luspatercept; dose titration up to 1·75 mg/kg was allowed, and patients could be treated with luspatercept for a maximum of 5 years. Patients in the base study were assessed for response and safety after 12 weeks in order to be considered for enrolment into the extension study. The primary endpoint was the proportion of patients achieving modified International Working Group-defined haematological improvement-erythroid (HI-E), defined as a haemoglobin concentration increase of 1·5 g/dL or higher from baseline for 14 days or longer in low transfusion burden patients, and a reduction in red blood cell transfusion of 4 or more red blood cell units or a 50% or higher reduction in red blood cell units over 8 weeks versus pre-treatment transfusion burden in high transfusion burden patients. Patient data were subcategorised by: luspatercept dose concentrations (0·125-0·5 mg/kg vs 0·75-1·75 mg/kg); pre-study transfusion burden (high transfusion burden vs low transfusion burden, defined as ≥4 vs <4 red blood cell units per 8 weeks); pre-study serum erythropoietin concentration (<200 IU/L, 200-500 IU/L, and >500 IU/L); presence of 15% or more ring sideroblasts; and presence of SF3B1 mutations. Efficacy analyses were carried out on the efficacy evaluable and intention-to-treat populations. This trial is currently ongoing. This study is registered with ClinicalTrials.gov, numbers NCT01749514 and NCT02268383. FINDINGS: Between Jan 21, 2013, and Feb 12, 2015, 58 patients with myelodysplastic syndromes were enrolled in the 12 week base study at nine treatment centres in Germany; 27 patients were enrolled in the dose-escalation cohorts (0·125-1·75 mg/kg) and 31 patients in the expansion cohort (1·0-1·75 mg/kg). 32 (63% [95% CI 48-76]) of 51 patients receiving higher dose luspatercept concentrations (0·75-1·75 mg/kg) achieved HI-E versus two (22% [95% CI 3-60]) of nine receiving lower dose concentrations (0·125-0·5 mg/kg). Three treatment-related grade 3 adverse events occurred in one patient each: myalgia (one [2%]), increased blast cell count (one [2%]), and general physical health deterioration (one [2%]). Two of these treatment-related grade 3 adverse events were reversible serious grade 3 adverse events: one patient (2%) had myalgia and one patient (2%) had general physical health deterioration. INTERPRETATION: Luspatercept was well tolerated and effective for the treatment of anaemia in lower-risk myelodysplastic syndromes and so could therefore provide a novel therapeutic approach for the treatment of anaemia associated with lower-risk myelodysplastic syndromes; further studies are ongoing. FUNDING: Acceleron Pharma.

The DART Study: Results from the Dose-Escalation and Expansion Cohorts Evaluating the Combination of Dalantercept plus Axitinib in Advanced Renal Cell Carcinoma.

Purpose: Activin receptor-like kinase 1 (ALK1) is a novel target in angiogenesis. Concurrent targeting of ALK1 and VEGF signaling results in augmented inhibition of tumor growth in renal cell carcinoma (RCC) xenograft models. Dalantercept is an ALK1-receptor fusion protein that acts as a ligand trap for bone morphogenetic proteins 9 and 10. The DART Study evaluated the safety, tolerability, pharmacokinetics, pharmacodynamics, and antitumor activity of dalantercept plus axitinib in patients with advanced RCC and determined the optimal dose for further testing.Experimental Design: Patients received dalantercept 0.6, 0.9, or 1.2 mg/kg subcutaneously every 3 weeks plus axitinib 5 mg by mouth twice daily until disease progression or intolerance.Results: Twenty-nine patients were enrolled in the dose escalation (n = 15) and expansion (n = 14) cohorts. There were no dose-limiting toxicities or grade 4/5 treatment-related adverse events. In addition to common VEGFR tyrosine kinase inhibitor effects, such as fatigue and diarrhea, commonly seen treatment-related adverse events were peripheral edema, epistaxis, pericardial effusion, and telangiectasia. The objective response rate by RECIST v1.1 was 25% with responses seen at all dose levels. The overall median progression-free survival was 8.3 months.Conclusions: The combination of dalantercept plus axitinib is well tolerated and associated with clinical activity. On the basis of safety and efficacy results, the 0.9 mg/kg dose level was chosen for further study in a randomized phase II trial of dalantercept plus axitinib versus placebo plus axitinib. Clin Cancer Res; 23(14); 3557-65. ©2016 AACR.

A phase 2 study of dalantercept, an activin receptor-like kinase-1 ligand trap, in patients with recurrent or metastatic squamous cell carcinoma of the head and neck.

BACKGROUND: Patients with platinum-refractory, recurrent or metastatic squamous cell carcinoma of the head and neck (RM-SCCHN) have limited options. Activin receptor-like kinase 1 (ALK1) is a type I receptor of the transforming growth factor ß superfamily expressed on activated endothelial cells. Dalantercept is an ALK1 receptor fusion protein that acts as a ligand trap to block signaling through ALK1 and inhibits stages of angiogenesis involved in blood vessel maturation and stabilization. In a phase 1 study, dalantercept demonstrated clinical activity in patients with RM-SCCHN. The objective of the current study was to evaluate the activity of dalantercept in RM-SCCHN. METHODS: Forty-six patients received dalantercept at doses of 80 mg (n = 2), 0.6 mg/kg (n = 13), or 1.2 mg/kg (n = 31) subcutaneously every 3 weeks. The primary endpoint was the overall response rate according to Response Evaluation Criteria in Solid Tumors (RECIST version 1.1). Secondary endpoints included progression-free survival and overall survival, safety and tolerability, and pharmacokinetic and pharmacodynamic assessments. RESULTS: Forty patients were evaluable for response (13 who received dalantercept 0.6 mg/kg and 27 who received dalantercept 1.2 mg/kg). The overall response rate was 5% (n = 2), and 35% of patients had stable disease; 44% of patients who received 1.2 mg/kg and 30.8% of those who received 0.6 mg/kg achieved disease control (partial response or stable disease). The median progression-fee survival was 1.4 months (95% confidence interval, 1.3-2.2 months), and the median overall survival was 7.1 months (95% confidence interval, 5.5-11.1 months). Drug-related adverse events (>15%) were anemia, fatigue, peripheral edema, headache, and hyponatremia. CONCLUSIONS: In an unselected, heavily pretreated population of patients with RM-SCCHN, dalantercept monotherapy resulted in a favorable safety profile but only modest dose-dependent activity, and it did not meet the primary efficacy objective of the study. Cancer 2016;122:3641-9. © 2016 American Cancer Society.

A phase 1 study of ACE-536, a regulator of erythroid differentiation, in healthy volunteers.

ACE-536, a recombinant protein containing a modified activin receptor type IIB, is being developed for the treatment of anemias caused by ineffective erythropoiesis, such as thalassemias and myelodysplastic syndromes. ACE-536 acts through a mechanism distinct from erythropoiesis-stimulating agents to promote late-stage erythroid differentiation by binding to transforming growth factor-ß superfamily ligands and inhibiting signaling through transcription factors Smad 2/3. The goal of this Phase 1 study was to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamic effects of ascending dose levels of ACE-536 in healthy volunteers. Thirty-two postmenopausal women were randomized in sequential cohorts of eight subjects each to receive up to two doses of either ACE-536 (0.0625-0.25 mg/kg) or placebo (3:1 randomization) given subcutaneously every 2 weeks. Mean baseline age was 59.4 years, and hemoglobin was 13.2 g/dL. ACE-536 was well tolerated at dose levels up to 0.25 mg/kg over the 1-month treatment period. There were no serious or severe adverse events, nor clinically meaningful changes in safety laboratory measures or vital signs. Mean ACE-536 AUC0-14d and Cmax increased proportionally after first dose; mean t½ was 15-16 days. Dose-dependent increases in hemoglobin concentration were observed, beginning 7 days after initiation of treatment and maintained for several weeks following treatment. The proportion of subjects with a hemoglobin increase ≥1.0 g/dL increased in a dose-dependent manner to 83.3% of subjects in the highest dose group, 0.25 mg/kg. ACE-536 was well tolerated and resulted in sustained increases in hemoglobin levels in healthy postmenopausal women.

Safety, pharmacokinetics, pharmacodynamics, and antitumor activity of dalantercept, an activin receptor-like kinase-1 ligand trap, in patients with advanced cancer.

PURPOSE: The angiogenesis inhibitor dalantercept (formerly ACE-041) is a soluble form of activin receptor-like kinase-1 (ALK1) that prevents activation of endogenous ALK1 by bone morphogenetic protein-9 (BMP9) and BMP10 and exhibits antitumor activity in preclinical models. This first-in-human study of dalantercept evaluated its safety, tolerability, pharmacokinetics, pharmacodynamics, and antitumor activity in adults with advanced solid tumors. EXPERIMENTAL DESIGN: Patients in dose-escalating cohorts received dalantercept subcutaneously at one of seven dose levels (0.1-4.8 mg/kg) every 3 weeks until disease progression. Patients in an expansion cohort received dalantercept at 0.8 or 1.6 mg/kg every 3 weeks until disease progression. RESULTS: In 37 patients receiving dalantercept, the most common treatment-related adverse events were peripheral edema, fatigue, and anemia. Edema and fluid retention were dose-limiting toxicities and responded to diuretic therapy. No clinically significant, treatment-related hypertension, proteinuria, gross hemorrhage, or gastrointestinal perforations were observed. One patient with refractory squamous cell cancer of the head and neck had a partial response, and 13 patients had stable disease according to RECISTv1.1, eight of whom had prolonged periods (≥12 weeks) of stable disease. Correlative pharmacodynamic markers included tumor metabolic activity and tumor blood flow, which decreased from baseline in 63% and 82% of evaluable patients, respectively, and telangiectasia in eight patients. CONCLUSION: Dalantercept was well-tolerated at doses up to 1.6 mg/kg, with a safety profile distinct from inhibitors of the VEGF pathway. Dalantercept displayed promising antitumor activity in patients with advanced refractory cancer, and multiple phase II studies are underway.