Endocyte Announces Enrollment of First Patient in Phase 3 VISION Trial

Endocyte, Inc. recently announced the enrollment of the first patient in its global phase 3 VISION trial of ¹⁷⁷Lu-PSMA-617 in prostate cancer by Dr. Luke Nordquist at Urology Cancer Center in Omaha, NE, a member of Precision Cancer Research. The international, prospective, open-label, multicenter, randomized Phase 3 study is evaluating patients with progressive prostate specific membrane antigen (PSMA)-positive metastatic castration-resistant prostate cancer (mCRPC), who have received at least one novel androgen axis drug (abiraterone or enzalutamide) and at least one taxane regimen.

“We are pleased to announce the initiation of this important clinical trial so quickly following our end-of-phase 2 meeting with the FDA. This speed of execution is a result of the enthusiasm of participating physicians and the focus and urgency of our clinical operations team,” said Mike Sherman, president and CEO of Endocyte. “Having collaborated with several of the key opinion leaders in prostate cancer around the world, we are confident in the robustness of the VISION trial design and eager to complete enrollment.”

“In spite of the introduction of new drugs in the last several years, there continues to be a significant need for therapeutic alternatives with new mechanisms of action for men suffering from metastatic castration-resistant prostate cancer,” added Oliver Sartor, MD, Medical Director of the Tulane Cancer Center. “The data generated with ¹⁷⁷Lu-PSMA-617 in early clinical trials have yielded a high level of enthusiasm among physicians. There is a real need to advance this investigational therapy as quickly as possible for these heavily pre-treated patients and begin the work to evaluate it in earlier lines of therapy, particularly in advance of chemotherapy.”

 Incremental data from an expansion cohort of 20 patients recently presented at ASCO confirmed and improved upon PSA response to ¹⁷⁷Lu-PSMA-617 previously reported in a cohort of 30 patients enrolled in a phase 2 trial at the Peter MacCallum Cancer Centre in Melbourne, Australia.

“Twenty-six of the 50 patients (52%) enrolled in this trial are more heavily pre-treated than the minimum eligibility criteria for the VISION trial, so it is particularly compelling to see a PSA decline of 50% or more in 62% of these advanced patients and a median PSA progression-free survival (PFS) of 7.0 months,” said Alison Armour, Chief Medical Officer of Endocyte. “While the overall survival data are not yet mature for the second cohort of 20 patients, we were pleased to see six-month survival rates similar to the first cohort of 30 patients. Consistent response rates across patient groups with variations in prior therapy is likely a result of a potential differentiated mechanism of action for ¹⁷⁷Lu-PSA-617 compared to currently approved therapies.”

 ¹⁷⁷Lu-PSMA-617 was generally well tolerated, with no significant dose-limiting toxicities observed. The most common treatment-related toxicity was Grade 1-2 xerostomia (dry mouth) seen in 68% of patients, but infrequently required any intervention. The occurrence of treatment-related Grade 3-4 hematologic toxicity was low and comparable to the largest retrospective published cohort.

VISION will enroll up to 750 patients worldwide with PSMA-positive scans, randomized in a 2:1 ratio to receive either ¹⁷⁷Lu-PSMA-617 plus best supportive/best standard of care versus best supportive/best standard of care alone.  Best supportive/best standard of care is palliative in nature and, at the discretion of the investigator, may include enzalutamide or abiraterone. Patients treated with ¹⁷⁷Lu-PSMA-617 will receive 7.4 gigabecquerel (GBq) intravenously every six weeks for a maximum of six cycles.

The primary endpoint of the study agreed to by the FDA is overall survival (OS). Secondary endpoints include radiographic progression-free survival (rPFS), response evaluation criteria in solid tumors (RECIST) response, and time to first symptomatic skeletal event. Two interim efficacy analyses of OS will be conducted at 50% and 70% of the first 489 targeted events. Endocyte plans to discuss modifying the first interim analysis endpoint to rPFS to expedite a potential accelerated approval in the U.S.  Further information on the global Phase 3 VISION study can be found at www.VISIONClinicalTrial.com.

Endocyte is a biopharmaceutical company and leader in developing targeted therapies for the personalized treatment of cancer. The company’s drug conjugation technology targets therapeutics and companion imaging agents specifically to the site of diseased cells. Endocyte’s lead program is a prostate specific membrane antigen (PSMA)-targeted radioligand therapy, ¹⁷⁷Lu-PSMA-617, entering phase 3 for metastatic castration-resistant prostate cancer (mCRPC). Endocyte also expects to have an Investigational New Drug application submitted in the fourth quarter of 2018 for its adaptor-controlled CAR T-cell therapy which will be initially studied in osteosarcoma. For more information, visit www.endocyte.com.