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Poster display session: Breast cancer - early stage, locally advanced & metastatic, CNS tumours, Developmental therapeutics, Genitourinary tumours - prostate & non-prostate, Palliative care, Psycho-oncology, Public health policy, Sarcoma, Supportive care

2945 - Preliminary results of the first-in-human, dose-finding PROCLAIM-CX-072 trial evaluating the PD-L1 Probody therapeutic CX-072 in combination with ipilimumab (ipi) in patients (pts) with advanced solid tumors


22 Oct 2018


Poster display session: Breast cancer - early stage, locally advanced & metastatic, CNS tumours, Developmental therapeutics, Genitourinary tumours - prostate & non-prostate, Palliative care, Psycho-oncology, Public health policy, Sarcoma, Supportive care


Clinical Research

Tumour Site


Ruth Plummer


Annals of Oncology (2018) 29 (suppl_8): viii133-viii148. 10.1093/annonc/mdy279


R. Plummer1, R.E. Sanborn2, E.G..E. de Vries3, P. Lorusso4, H. Arkenau5, N. Uboha6, J. Wydmanski7, M.J. Fidler8, V. Boni9, J. Garcia-Corbacho10, R. Humphrey11, M. Will11, K.A. Autio12, A.B. El-Khoueiry13, C.W. Menke-van der Houven van Oordt14, F. Thistlethwaite15

Author affiliations

  • 1 Northern Institute For Cancer Research, Newcastle University, NE2 4HH - Newcastle upon Tyne/GB
  • 2 Earle A. Chiles Research Institute, Providence Cancer Institute, Portland/US
  • 3 Medical Oncology, Universitair Medisch Centrum Groningen, 9700 RB - Groningen/NL
  • 4 Yale Cancer Center, Yale University School of Medicine, New Haven/US
  • 5 Scri, Sarah Cannon Research Institute SCRI UK, W1G 6AD - London/GB
  • 6 Carbone Cancer Center, University of Wisconsin, Madison/US
  • 7 Vegamed, NZOZ, Katowice/PL
  • 8 Medical Oncology, Rush University Medical Center, Chicago/US
  • 9 Medical Oncology, START Madrid-CIOCC HM Hospital Sanchinarro, Madrid/ES
  • 10 Medical Oncology, Hospital Clinic Barcelona, Barcelona/ES
  • 11 Medical Oncology, CytomX Therapeutics, South San Francisco/US
  • 12 Medical Oncology, Memorial Sloan Kettering Cancer Center, New York/US
  • 13 Medical Oncology, USC/Norris Comprehensive Cancer Center, Los Angeles/US
  • 14 Medical Oncology, VUMC Cancer Centre Amsterdam, Amsterdam/NL
  • 15 Medical Oncology, The Christie NHS Foundation Trust and University of Manchester, M20 4BX - Manchester/GB


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Abstract 2945


Combination treatment with PD-1 + CTLA-4 checkpoint inhibitors shows improvement in breadth, depth, and durability of response, coupled with a disproportionate increase in immune-related adverse events (irAE). CX-072, a Probody™ therapeutic (Pb-Tx) directed against PD-L1, is designed to be preferentially activated by tumor-associated proteases and not in healthy tissue. Preclinically, anti–PD-1 Pb-Tx + anti–CTLA-4 showed comparable efficacy with improved safety compared to the non–Pb-Tx combination control. This dose-escalation cohort examines safety and tolerability of CX-072 (anti-PD-L1 Pb-Tx) + the CTLA-4 inhibitor ipi in pts with advanced solid tumors.


In this ongoing phase 1/2 study (NCT03013491), PD-1, PD-L1, and CTLA-4 inhibitor-naive pts receive combination CX-072 + ipi (part B1). Planned doses of CX-072 (0.3, 1, 3, or 10 mg/kg) are administered in combination with ipi (3, 6, or 10 mg/kg) every 21 days for 4 cycles, followed by CX-072 monotherapy every 14 days.


As of April 20, 2018, part B1 enrolled 16 pts. Median age (range) and number of prior anticancer treatments was 60 years (28-70) and 3 (1-12), respectively. 6 pts were still on treatment at time of data cut. Median number (range) of CX-072 (0.3, 1, 3, or 10 mg/kg) and ipi (3 mg/kg) doses were 3 (1-20) and 3 (1-4), respectively. All cohorts through 10 mg/kg CX-072 (dose selected for monotherapy cohort expansion) are now enrolled without reaching the MTD. 1 DLT (grade 3 dyspnea, 0.3 mg/kg CX-072 + ipi) occurred. Grade 3 treatment-related (TR) irAEs occurred in 2 pts (12.5%; colitis and dyspnea/pneumonitis). No subject discontinued due to TR irAEs. Best response in 10 evaluable pts included 1 complete response (anal SCC, 0.3 mg/kg CX-072 + ipi), 2 partial response (non-seminoma testicular, 1 mg/kg CX-072 + ipi; small bowel, 3 mg/kg CX-072 + ipi), 1 stable disease, and 6 progressive disease.


Despite small pt numbers and limited follow up, early data suggest manageable safety profiles at all doses and antitumor activity with CX-072 + ipi in tumor types not approved for checkpoint inhibitors. The study is ongoing and escalation of ipi to 10 mg/kg is pending.

Clinical trial identification


Legal entity responsible for the study

CytomX Therapeutics, Inc.


CytomX Therapeutics, Inc.

Editorial Acknowledgement

Editorial support was provided by Andrew Occiano (ApotheCom, San Francisco, CA).


R.E. Sanborn: Research funding/grant: Merck; Investigator initiated Study: BMS, Medimmune; Institutional research support, honoraria: AstraZeneca; Advisory board: AstraZeneca, Seattle Genetics, Takeda, Genentech, Abbvie, Celldex; Travel, accommodations, investigator meeting: Janssen. E.G.E. de Vries: Research grant: Amgen, Genentech, Roche, Chugai, Synthon, CytomX, Nordic Nanovector, Regeneron, G1 Therapeutics, AstraZeneca, Radius Health (institution); Consulting: Pfizer, Sanofi (institution). P. Lorusso: Data safety monitoring board: Agios, FivePrime, Halozyme; Advisory board: Alexion, Ariad, CytomX, GenMab, Genentech, Glenmark, Ignyta, Menarini, Novartis, Omniox, Takeda, imCORE Alliance, Roche-Genentech. N. Uboha: Consulting: EMD Serono, Lilly, FlatIron, GLG. M.J. Fidler: Consulting: Genentech, AstraZeneca, Takeda, AbbVie; Speakers bureau: Merck, Celgene, Genentech, AbbVie. R. Humphrey, M. Will: Employment: CytomX Therapeutics. K.A. Autio: Research funding: CytomX, Pfizer, Lilly, GSK, Merck, ARMO Biosciences. F. Thistlethwaite: Research grant: Novartis; Consulting: Pfizer, BMS, Octimet, Achilles Therapeutics, Evelo Biosciences; Honorarium: Novartis; Speakers' bureau: BMS. All other authors have declared no conflicts of interest.

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