On June 10, 2022 Oncternal Therapeutics, Inc. (Nasdaq: ONCT), a clinical-stage biopharmaceutical company focused on the development of novel oncology therapies, reported that the rationale and plans for its upcoming Phase 3 ZILO-301 (zilovertamab plus ibrutinib targeting ROR1 for patients with Mantle Cell Lymphoma) clinical trial will be highlighted in a poster presentation at the European Hematology Association (EHA) (Free EHA Whitepaper) 2022 Hybrid Congress (Press release, Oncternal Therapeutics, JUN 10, 2022, View Source [SID1234615874]). ZILO-301 is designed to evaluate the efficacy and safety of zilovertamab, an investigational anti-ROR1 monoclonal antibody, plus ibrutinib compared to ibrutinib monotherapy for the treatment of patients with relapsed or refractory mantle cell lymphoma (R/R MCL).
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Poster Title: Study ZILO-301: A Phase 3, Randomized, Double-Blind, Placebo-Controlled, Multicenter Study of Zilovertamab Plus Ibrutinib vs. Ibrutinib in Patients with Relapsed or Refractory Mantle Cell Lymphoma
Abstract Number: P1154
Session Title: Indolent and mantle-cell non-Hodgkin lymphoma – Clinical
Session Date and Time: June 10, 2022 at 16:30 CEST
"The recently announced updated interim data from our Phase 1/2 study presented at ASCO (Free ASCO Whitepaper) 2022, provides ample support for the rationale of the design of our global registration Phase 3 study, ZILO-301, evaluating the combination of zilovertamab and ibrutinib in patients with MCL," noted Salim Yazji, M.D., Oncternal’s Chief Medical Officer. "We are excited to pursue a registrational pathway for zilovertamab based on an innovative enrichment study design that we believe can provide both an accelerated approval and regular approval in a single study. We expect to initiate ZILO-301 in the third quarter of 2022."
Zilovertamab is being evaluated in combination with ibrutinib in patients with R/R MCL and chronic lymphocytic leukemia (CLL) in the Phase 1/2 study, CIRM-0001. The most recent interim data update showed an Objective Response Rate (ORR) of 85% and a Complete Response (CR) rate of 41% in 27 evaluable patients with mantle cell lymphoma, both of which compare favorably to the historical ORR of 66% and CR rate of 20% for ibrutinib monotherapy.
The phase 3 study, ZILO-301, will evaluate the potential benefit for patients who achieve either a partial response (PR) or stable disease (SD) during a lead-in with ibrutinib monotherapy. Initially, patients enrolled in ZILO-301 will receive single agent ibrutinib (560 mg daily) for 4 months. Patients with an inadequate response (PR or SD) will be randomized (1:1) to receive zilovertamab or placebo while continuing to receive ibrutinib. The study aims to randomize approximately 250 patients.
Key Inclusion criteria:
Adults with histologically confirmed MCL
Relapsed or refractory with at least 1 prior therapy
Primary Objective
Progression-free survival (PFS) among subjects who had a PR or SD after open-label ibrutinib monotherapy phase and were randomized to receive zilovertamab + ibrutinib or ibrutinib + placebo
Secondary Objectives
Objective Response Rate (ORR) and Duration of Response (DoR)
Complete Response Rate (CR Rate)
Overall Survival (OS)
Proportion of subjects experiencing grade 3 or 4 neutrophil count decrease and overall safety profile
About Zilovertamab
Zilovertamab is an investigational, humanized, potentially first-in-class monoclonal antibody targeting Receptor tyrosine kinase-like Orphan Receptor 1 (ROR1). Zilovertamab is currently being evaluated in a Phase 1/2 clinical trial in combination with ibrutinib for the treatment of patients with MCL, chronic lymphocytic leukemia (CLL) or MZL, in a collaboration with the University of California San Diego (UC San Diego) School of Medicine and the California Institute for Regenerative Medicine (CIRM). In addition, Oncternal is supporting two investigator-sponsored studies being conducted at the UC San Diego School of Medicine, a Phase 1b clinical trial for patients with metastatic castration-resistant prostate cancer (mCRPC), and a Phase 2 clinical trial of zilovertamab in combination with venetoclax, a Bcl-2 inhibitor, for patients with relapsed/refractory CLL. Both are open for enrollment.
ROR1 is a potentially attractive target for cancer therapy because it is an onco-embryonic antigen, not usually expressed on adult cells, but its expression confers a survival and fitness advantage when reactivated and expressed by tumor cells. Researchers at the UC San Diego School of Medicine discovered that targeting a critical epitope on ROR1 was key to specifically inhibiting ROR1-expressing tumors. This led to the development of zilovertamab which binds this critical epitope of ROR1, highly expressed on many different cancers but not on normal tissues. Preclinical data showed that when zilovertamab bound to ROR1, it blocked Wnt5a signaling, inhibited tumor cell proliferation, migration and survival, and induced differentiation of the tumor cells. The FDA has granted Orphan Drug Designations to zilovertamab for the treatment of patients with MCL and CLL/small lymphocytic lymphoma. Zilovertamab is in clinical development and has not been approved by the FDA for any indication.