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Poster display

4300 - Phase 1 study of the PSMA-targeted tubulysin small-molecule drug conjugate EC1169 in patients with metastatic castrate-resistant prostate cancer (mCRPC): Study update


09 Oct 2016


Poster display


Michael Morris


Annals of Oncology (2016) 27 (6): 243-265. 10.1093/annonc/mdw372


M.J. Morris1, N.J. Vogelzang2, O. Sartor3, A. Armour4, D. Petrylak5, A. Tolcher6, S. Ejadi7, H.M. Babiker8

Author affiliations

  • 1 Medical Oncology, Memorial Sloan-Kettering Cancer Center, 10065 - New York, NY/US
  • 2 Medical Oncology, US Oncology Research c/o Comprehensive Cancer Crts of NV, Las Vegas/US
  • 3 Dept. Of Medicine & Urology, Tulane University, 70112 - New Orleans/US
  • 4 Clinical, Endocyte, Inc, 46268 - Indianapolis/US
  • 5 Medical Oncology, Smilow Cancer Hospital at Yale-New Haven, 208032 - New Haven/US
  • 6 Clinical Research, START - South Texas Accelerated Research Therapeutics, LLC, 78229 - San Antonio/US
  • 7 Clinical Trials, Virginia G. Piper Cancer Center at Scottsdale Healthcare, 85258 - Scottsdale/US
  • 8 Clinical Oncology, Honor Health, Scottsdale/US


Abstract 4300


Prostate-specific membrane antigen (PSMA) is overexpressed by most prostate cancers. EC1169 is a conjugate of a PSMA targeting moiety linked to the cytotoxic agent tubulysin B hydrazide (TubBH). Following internalization of EC1169 by targeted cancer cells, intracellular release of TubBH results in inhibition of tubulin polymerization. In PSMA-positive LNCaP and MDA PCa 2b xenografts, complete responses and cures have been observed following EC1169 treatment. EC1169 does not show activity in PSMA-negative models, demonstrating its specificity. EC0652 is a companion radiodiagnostic conjugate of a 99mTc chelator and a PSMA-targeting moiety designed to characterize PSMA-expressing disease in real time. Rapid tumor uptake of 99mTc-EC0652 and rapid normal tissue clearance result in enhanced tumor: background ratios with SPECT imaging.


Key inclusion criteria are age ≥18 years, ECOG PS 0–1, and adequate organ function. Patients (pts) must have failed androgen-deprivation therapy, progressed on abiraterone or enzalutamide, and have been previously treated with a taxane unless contraindicated. Patients are to undergo a 99mTc-EC0652 SPECT scan prior to therapy. PSMA positivity is not a requirement for study entry. EC1169 is administered as an intravenous bolus on Days (D) 1, 8 (QW) every 21 D. Dose escalation is based upon the “3 + 3” method. Study objectives include determination of EC1169 MTD and recommended phase II dose, safety, pharmacokinetics, antitumor activity and its correlation with PSMA expression as identified on 99mTc-EC0652 SPECT imaging.


23 pts have been treated on the QW schedule. Median age is 70 (range: 57-82). The median number of administered EC1169 cycles is 2 (range: 1-11). 12 (52%) treatment related AEs have been reported. Most common Grade 3/4 AEs were anaemia (2; 8.7%) and lymphopenia (2; 8.7%). No DLT, related SAEs or toxicity requiring dose reductions occurred. PSA response (≥50% max decline) has been observed in 2 pts. Data will be updated at the meeting.


To date, EC1169 has been well tolerated. There are promising signs of early efficacy in this heavily pre-treated population.

Clinical trial identification

ClinicalTrials.gov NCT02202447

Legal entity responsible for the study

Endocyte, Inc.


Endocyte, Inc.


M.J. Morris: MSKCC receives funding from Endocyte for the conduct of this study. I've received funding for advisory boards from Progenics, Tokai, & Millennium Pharmaceuticals. I'm an uncompensated advisor for Bayer, which my institution also receives funding. O. Sartor, D. Petrylak: Endocyte: consultancy fees.

A. Armour: Alison Armour is an employee of Endocyte. H.M. Babiker: Endocyte: consultancy fees. Celgene: Consultant/Advisory Board. SirTex: Honorarium. All other authors have declared no conflicts of interest.

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