A Phase I Study of the Anti-Activin Receptor-Like Kinase 1 (ALK-1) Monoclonal Antibody PF-03446962 in Patients with Advanced Solid Tumors

Clin Cancer Res. 2016 May 1;22(9):2146-54. doi: 10.1158/1078-0432.CCR-15-1622. Epub 2015 Dec 11.


Purpose: Objectives of this dose-finding study were to determine the MTD and recommended phase II dose (RP2D) of the first-in-class anti-activin receptor-like kinase 1 (ALK-1) monoclonal antibody PF-03446962, and assess safety and antitumor activity in patients with advanced solid tumors.

Experimental design: This open-label, multicenter study was based on a 3+3 design. PF-03446962 was administered biweekly by intravenous infusion, at doses ranging from 0.5 to 15 mg/kg.

Results: Forty-four patients received treatment with PF-03446962. Dose-limiting toxicities observed during dose escalation included grade 3 increased amylase, grade 3/4 increased lipase, and grade 3/4 thrombocytopenia. The MTD was determined to be 10 mg/kg. The RP2D was set at 7 mg/kg for patients with advanced solid tumors, based on the observed safety, pharmacokinetics, and antitumor activity. The most-frequent treatment-related, all-grade adverse events included thrombocytopenia (20.5%), fatigue (15.9%), and nausea, increased amylase, and increased lipase (each 11.4%). Treatment-related telangiectasia was noted in 7% of patients, suggesting in vivo inhibition of the ALK-1 pathway. None of the deaths was deemed to be treatment-related. Three (6.8%) patients with advanced hepatocellular carcinoma, renal cell carcinoma, or non-small cell lung cancer achieved a partial response, and 12 (27.3%) patients had stable disease, across dose levels. Contrast-enhanced ultrasound analysis of tumor vascularity showed reduction in tumor perfusion in 2 patients with stable disease following treatment with PF-03446962.

Conclusions: The clinical activity demonstrated in this study points to PF-03446962 as a novel approach to antiangiogenic therapy, with manageable safety profile and single-agent, antitumor activity in patients with advanced solid tumors. Clin Cancer Res; 22(9); 2146-54. ©2015 AACR.

Trial registration: ClinicalTrials.gov NCT00557856.

Publication types

  • Clinical Trial, Phase I
  • Multicenter Study

MeSH terms

  • Activin Receptors, Type II / immunology*
  • Adult
  • Aged
  • Aged, 80 and over
  • Antibodies, Monoclonal / therapeutic use*
  • Antibodies, Monoclonal, Humanized
  • Antineoplastic Agents / therapeutic use*
  • Dose-Response Relationship, Drug
  • Female
  • Humans
  • Male
  • Middle Aged
  • Neoplasms / drug therapy*
  • Treatment Outcome


  • Antibodies, Monoclonal
  • Antibodies, Monoclonal, Humanized
  • Antineoplastic Agents
  • ascrinvacumab
  • ACVRL1 protein, human
  • Activin Receptors, Type II

Associated data

  • ClinicalTrials.gov/NCT00557856