SAN DIEGO, May 26, 2022 (GLOBE NEWSWIRE) -- Oncternal Therapeutics, Inc. (Nasdaq: ONCT), a clinical-stage biopharmaceutical company focused on the development of novel oncology therapies, today announced updated interim clinical data from the ongoing Phase 1/2 CIRLL (Cirmtuzumab and Ibrutinib targeting ROR1 for Leukemia and Lymphoma) clinical trial, that will be presented in a poster presentation at the American Society of Clinical Oncology (ASCO) 2022 Annual Meeting. In the CIRLL study, zilovertamab, an investigational anti-ROR1 monoclonal antibody, is being evaluated in combination with ibrutinib in patients with mantle cell lymphoma (MCL) and chronic lymphocytic leukemia (CLL). The clinical trial is being conducted in collaboration with the University of California San Diego (UC San Diego) and has been partially funded by the California Institute for Regenerative Medicine (CIRM).
The updated interim data will be presented as a poster discussion session at the Hematologic Malignancies—Lymphoma and Chronic Lymphocytic Leukemia session on Saturday, June 4, 2022 as part of the ASCO 2022 Annual Meeting:
“The interim data update presented today further strengthens our confidence in the significant clinical value the combination of zilovertamab and ibrutinib can deliver to MCL and CLL patients. Solid objective response rate (ORR) of 85% and median progression-free survival (PFS) of 36 months in heavily pre-treated MCL patients in our CIRLL study support our Phase 3 registrational study ZILO-301, which we plan to initiate in the third quarter,” said James Breitmeyer, M.D., Ph.D., Oncternal’s President and CEO. “We continue to be especially intrigued by the encouraging and robust response rate across multiple populations of high-risk MCL and CLL patients, most notably the prolonged PFS seen for those that express the p53 mutation, a particularly challenging population for BTK inhibitors. This is further proof that the combination is very active, and we believe it may address important unmet medical needs in difficult-to-treat patients with aggressive forms of hematological malignancies.”
The results that will be presented in poster form and reviewed in a poster discussion at the ASCO 2022 Annual Meeting include 33 patients with relapsed/refractory MCL enrolled in the dose-finding and dose-expansion cohorts of the CIRLL clinical trial (Part 1 + Part 2), of whom 27 were evaluable for efficacy as of the April 8, 2022 data cut-off date.
Thirty-four patients with CLL enrolled in the dose-finding and dose-confirming cohorts of this clinical trial (Part 1 & Part 2) as of the April 8, 2022 data cut-off date, were all evaluable for efficacy. Patients had high-risk factors, and most were heavily pre-treated at study entry, with 71% having RAI staging ≥2 and a median of two systemic prior therapies (range 1-9).
Thirty-one patients with CLL have also been enrolled in the randomized efficacy cohort of this clinical trial (Part 3), of which 23 were evaluable for efficacy. Data on this cohort are maturing. The median PFS had not been reached for either group as of the April 8, 2022 cut-off date after 24 months of follow up.
The combination of zilovertamab plus ibrutinib has been well tolerated, with treatment emergent adverse events consistent with those reported for ibrutinib alone. There have been no dose-limiting toxicities and no serious adverse events attributed to zilovertamab alone. In patients with MCL, Grade 3-4 neutrophil decrease was documented in 9.1% of patients with zilovertamab plus ibrutinib, compared to 29% for ibrutinib alone from its registration study.
About the CIRLL Clinical Trial
The CIRLL clinical trial (CIRM-0001) is a Phase 1/2 trial evaluating zilovertamab in combination with ibrutinib in separate groups of patients with CLL or MCL. Enrollment of the dose-finding cohorts in CLL and MCL, dose-expansion cohort in CLL and MCL and randomized Phase 2 cohort in CLL has been completed. An additional dose-expansion cohort of up to 10 patients with marginal zone lymphoma (MZL) has recently been added. Enrollment is expected to begin in Q2 2022. Additional information about the CIRM-0001 clinical trial and other clinical trials of zilovertamab may be accessed at ClinicalTrials.gov.
About Zilovertamab
Zilovertamab (formerly designated cirmtuzumab) 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.
About Oncternal Therapeutics
Oncternal Therapeutics is a clinical-stage biopharmaceutical company focused on the development of novel oncology therapies for the treatment of patients with cancers that have critical unmet medical need. Oncternal pursues drug development targeting promising, yet untapped biological pathways implicated in cancer generation or progression, focusing on hematological malignancies and prostate cancer. The lead clinical program is zilovertamab, an investigational monoclonal antibody designed to inhibit ROR1, a type I tyrosine kinase-like orphan receptor. Zilovertamab is being evaluated in a Phase 1/2 clinical trial in combination with ibrutinib for the treatment of patients with mantle cell lymphoma (MCL) and chronic lymphocytic leukemia (CLL), in investigator-initiated studies, including a Phase 2 clinical trial of zilovertamab in combination with venetoclax, a Bcl-2 inhibitor, in patients with relapsed/refractory CLL, and in a Phase 1b study of zilovertamab in combination with docetaxel in patients with metastatic castration-resistant prostate cancer (mCRPC). Oncternal is also developing ONCT-808, a chimeric antigen receptor T cell (CAR-T) therapy that targets ROR1, which is currently in preclinical development as a potential treatment for hematologic cancers and solid tumors. The early-stage pipeline also includes ONCT-534, a dual-action androgen receptor inhibitor (DAARI), that is in preclinical development as a potential treatment for castration resistant prostate cancer, including those with clinically important resistance to approved androgen receptor inhibitors. More information is available at https://oncternal.com/.
Forward-Looking Information
Oncternal cautions you that statements included in this press release that are not a description of historical facts are forward-looking statements. In some cases, you can identify forward-looking statements by terms such as “may,” “will,” “should,” “expect,” “plan,” “anticipate,” “could,” “intend,” “target,” “project,” “contemplates,” “believes,” “estimates,” “predicts,” “potential” or “continue” or the negatives of these terms or other similar expressions. These statements are based on Oncternal’s current beliefs and expectations. Forward-looking statements include statements regarding the potential for zilovertamab in combination with ibrutinib to treat MCL or CLL; the potential that Study ZILO-301 can serve as a registrational clinical trial; and the expected initiation or enrollment of clinical trials, including Study ZILO-301. Forward-looking statements are subject to risks and uncertainties inherent in Oncternal’s business, including risks associated with the clinical development and process for obtaining regulatory approval of Oncternal’s product candidates, such as potential delays in the commencement, enrollment and completion of clinical trials; Oncternal has not conducted head-to-head studies of zilovertamab in combination with ibrutinib compared to ibrutinib monotherapy and data from separate studies may not be directly comparable due to the differences in study protocols, conditions and patient populations; the risk that interim results of a clinical trial do not predict final results and that one or more of the clinical outcomes may materially change as patient enrollment continues, following more comprehensive reviews of the data, as follow-up on the outcome of any particular patient continues, and as more patient data become available; later developments with the FDA may be inconsistent with the minutes from the completed end of Phase 2 meeting, including that the proposed Study ZILO-301 that may not support registration of zilovertamab in combination with ibrutinib which is a review issue with the FDA upon submission of a BLA; and other risks described in Oncternal’s filings with the U.S. Securities and Exchange Commission. All forward-looking statements in this press release are current only as of the date hereof and, except as required by applicable law, Oncternal undertakes no obligation to revise or update any forward-looking statement, or to make any other forward-looking statements, whether as a result of new information, future events or otherwise. All forward-looking statements are qualified in their entirety by this cautionary statement. This caution is made under the safe harbor provisions of the Private Securities Litigation Reform Act of 1995.
Contact Information:
Investors
Richard Vincent
858-434-1113
[email protected]
Media
Corey Davis, Ph.D.
LifeSci Advisors
212-915-2577
[email protected]
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