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Poster display session

5399 - The First-in-Human, Dose-Finding PROCLAIM-CX-072 Trial to Assess the Antitumor Activity and Tolerability of the Probody Therapeutic CX-072 as Monotherapy and in Combination With Ipilimumab or Vemurafenib in Solid Advanced Tumors and Lymphomas


11 Sep 2017


Poster display session




Valentina Boni


Annals of Oncology (2017) 28 (suppl_5): v122-v141. 10.1093/annonc/mdx367


V. Boni1, J. Garcia-Corbacho2, J. Feliu3, J. Wydmanski4, Z. Horvath5, I. Bondarenko6, B. Irving7, M. Will7, E.G..E. de Vries8, F. Thistlethwaite9

Author affiliations

  • 1 Oncology, START Madrid-CIOCC, 28050 - Madrid/ES
  • 2 Oncology, Hospital Clinic Barcelona, 8036 - Barcelona/ES
  • 3 Oncology, Hospital Universitario La Paz, Madrid/ES
  • 4 Oncology, NZOZ Vegamed, Katowice/PL
  • 5 Oncology, Debreceni Egyetem Klinikai Kozpont, Debrecen/HU
  • 6 Oncology, Dnipropetrovsk State Medical Academy, Dnepropetrovsk/UA
  • 7 Oncology, CytomX Therapeutics, South San Francisco/US
  • 8 Medical Oncology, Universitair Medical Center Groningen, 9700 RB - Groningen/NL
  • 9 Oncology, The Christie NHS Foundation Trust and University of Manchester, Manchester/GB


Abstract 5399


CX-072 is a novel protease activatable prodrug (Probody™ therapeutic) derived from a human monoclonal antibody against programmed cell death ligand 1 (PD-L1). CX-072 was designed to restrict its activity to the tumor microenvironment and remain largely inactive in nonmalignant tissue. A surrogate molecule for CX-072 displayed potent antitumor activity with reduced systemic immune activation and immune-related toxicities in preclinical tumor models, potentially enabling new and more effective combination therapies. The phase 1/2 PROCLAIM-CX-072 (PRObody CLinical Assessment In Man) study will assess the safety, tolerability, and antitumor activity of CX-072, as monotherapy and in combination, in adults with advanced or recurrent solid tumors and lymphomas.

Trial design

In an open-label, multicenter, dose-escalation, 3 + 3 design, CX-072 will be administered as monotherapy (Part A) in 2 combination schedules with ipilimumab 3 mg/kg 3 weekly × 4 (Parts B1 and B2) and in combination with vemurafenib 960 mg/kg twice daily (Part C). The expansion cohort (Part D) will include CX-072 monotherapy in PD-L1–responsive tumor types. Patient recruitment was initiated on January 11, 2017. Key inclusion criteria are: Parts A and B1—advanced, refractory solid tumor or lymphoma in checkpoint inhibitor-naive patients for whom approved PD agents are not available; Part B2—advanced, refractory solid tumors or lymphomas with measurable disease that progressed on previous treatment with a PD-1/PD-L1 inhibitor but patients did not discontinue due to toxicity; Part C—checkpoint inhibitor, BRAF-inhibitor, and MEK-inhibitor-naive metastatic V600E BRAF-mutated melanoma. Efficacy will be determined according to irRECIST v1.1 criteria, and safety and tolerability will be assessed based on the incidence and nature of dose-limiting toxicities, adverse events (AEs), and serious AEs. Exploratory biomarkers will be used to characterize tumor protease activity, immune response pattern within the tumor, and CX-072 activation in tumor vs peripheral blood.

Clinical trial identification


Legal entity responsible for the study

CytomX Therapeutics, South San Francisco, CA, USA


CytomX Therapeutics, South San Francisco, CA, USA


J. Wydmanski: Consultant to Bristol-Myers Squibb. B. Irving, M. Will: Employee of CytomX Therapeutics. F. Thistlethwaite: Personal fees from Novartis, Bristol-Myers Squibb, Pfizer, and Ipsen. All other authors have declared no conflicts of interest.

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