Sutro Biopharma Presents Data from Ongoing Phase 1 Dose-Escalation Study for STRO-001 for the Treatment of B-cell Non-Hodgkin Lymphoma at the 62nd American Society of Hematology Annual Meeting

On December 7, 2020 Sutro Biopharma, Inc. (NASDAQ: STRO), a clinical-stage drug discovery, development and manufacturing company focused on the application of precise protein engineering and rational design to create next-generation cancer and autoimmune therapeutics, reported a poster presentation at the virtual 62nd American Society of Hematology (ASH) (Free ASH Whitepaper) Annual Meeting for the ongoing Phase 1 dose-escalation clinical trial for its CD74-targeted antibody drug conjugate (ADC) STRO-001 for patients with late-line Non-Hodgkin Lymphoma (NHL) (Press release, Sutro Biopharma, DEC 7, 2020, View Source [SID1234572388]). Additionally, data were presented from preclinical studies conducted in collaboration with researchers from the Fred Hutchinson Cancer Research Center.

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"With three product candidates in the pipeline actively enrolling patients—STRO-001, STRO-002, our folate receptor alpha- (FolRα) targeting ADC, and CC-99712 in partnership with Bristol Myers Squibb, a BCMA-targeting ADC—Sutro is working on addressing unmet needs via targeted therapies that can tackle cancer evolution," said Bill Newell, Sutro’s Chief Executive Officer. "The encouraging safety and preliminary efficacy clinical data presented at ASH (Free ASH Whitepaper) on STRO-001 for the treatment of late-line NHL further validates our platform and unique approach to ADC design, creating potential first-in-class and/or best-in-class therapeutic candidates."

STRO-001 Phase 1 Dose Escalation Interim Data
STRO-001-BCM1 is an ongoing first-in-human, phase 1 dose-escalation study evaluating the safety, tolerability, and preliminary antitumor activity of STRO-001 in adults with B-cell malignancies. The study is ongoing, and data presented at ASH (Free ASH Whitepaper) included results from the NHL cohort. There were 21 NHL patients treated and 18 evaluable patients for response. Patients had a median of 5 prior therapies. 6/21 patients (29%) had previous stem cell transplant or CAR-T therapy. Data as of October 30, 2020 are as follows:

Most (90%) treatment-emergent adverse events (TEAEs) were grade 1 or 2 and no ocular or neuropathy toxicity signals have been observed
Following a previously announced protocol amendment last year requiring pre-treatment screening imaging for patients at risk for thromboses, no additional thromboembolic events have been observed
In the 7 patients with diffuse large B-cell lymphoma (DLBCL), 1 complete response (CR) and 2 partial responses (PRs) were observed
Out of other NHL types, 2 patients with follicular lymphoma had stable disease (SDs), of which one is still on treatment at 9 weeks. One patient with marginal zone lymphoma had SD and is still on treatment at 39 weeks
"These results continue to demonstrate the potential clinical benefit of STRO-001 treatment in patients with NHL who are heavily pretreated, with a median of five prior lines of treatment," said Dr. Arturo Molina, Sutro’s Chief Medical Officer. "We are especially pleased for the patients who responded to STRO-001 after previously progressing on CAR-T treatments and an additional post- CAR-T regimen to which they had no response, seeing comparable duration of disease control to the duration on a cell therapy. STRO-001 has been well tolerated. We look forward to continuing the dose-escalation study to learn more about the potential for STRO-001 for patients with NHL."

Maximum tolerated dose (MTD) was not reached at 2.5 mg/kg. Active enrollment in the NHL cohort continues at the 3.5 mg/kg dose level and additional higher dose levels may be explored. The trial, registered with clinicaltrials.gov identifier NCT03424603, continues to enroll patients in dose escalation in both multiple myeloma (MM) and NHL cohorts.

The virtual poster titled "Preliminary Results of an Ongoing Phase 1 Dose Escalation Study of the Novel Anti-CD74 Antibody Drug Conjugate (ADC), STRO-001, in Patients with B-cell Non-Hodgkin Lymphoma," presented by Nirav N. Shah, M.D., Associate Professor of Medicine at Medical College of Wisconsin, is accessible through the Clinical/Scientific Presentation and Publication Highlights page of the News section of the company’s website at www.sutrobio.com.

Preclinical Data from Fred Hutchinson Cancer Research Center in Collaboration with Sutro
Fred Hutchinson Cancer Research Center, in collaboration with Sutro, presented preclinical models showing the potential of CD74-targeted therapies, and in particular STRO-001, for the treatment of acute myelogenous leukemia (AML). The research is out of the lab of Soheil Meshinchi, M.D., Ph.D., Professor, Clinical Research Division at Fred Hutchinson Cancer Center and Professor of Pediatrics at University of Washington School of Medicine.

"My team at Fred Hutchinson Cancer Research Center has built a robust computational platform leveraging our large AML transcriptome dataset to identify highly expressed antigens on leukemic cells that are being targeted by agents in early phase trials or preclinical development with the goal of repurposing these therapeutics for use in AML," said Soheil Meshinchi, M.D., Ph.D. "One of these therapies was the STRO-001 ADC which targets the cell surface protein CD74. We have demonstrated that CD74 is highly expressed in a significant proportion of patients with AML. Our initial studies of STRO-001 ADC in AML cell lines demonstrated robust in vitro cytotoxicity on AML cell lines expressing high- to moderate-levels of CD74, with no cytotoxicity in cells with no CD74 expression. This in vitro data, which identifies CD74 as a viable target in AML, coupled with the 27% incidence of CD74 in nearly 1,000 pediatric AML patients from our clinical trial with bortezomib, strengthens the notion that targeting CD74 with STRO-001 represents a viable targeted therapy in this patient population. In addition to AML, CD74 is highly expressed in high risk acute lymphoblastic leukemia (ALL), including Ph-positive and Ph-like ALL, thus providing rationale for exploring the efficacy of STRO-001 in all leukemias.

A virtual poster titled "Target-Informed Repurposing of Immunotherapies in AML – a Transcriptome Based Approach for Identifying Immediately Available Therapeutics," will be presented Amanda Leonti, MS, Computational Biology, Meshinchi lab, Fred Hutchinson Cancer Research Center, and include in vitro cytotoxicity data for STRO-001 in AML cell lines. See the abstract here.
A virtual oral session titled "Newly Diagnosed Childhood AML Patients Treated with Bortezomib Show Superior Survival If CD74 Is Expressed: A Report of 991 Patients from the Children’s Oncology Group AAML1031 Protocol," will be presented by Lisa Eidenschink Brodersen PhD HCLD, Director, Flow Cytometry, Hematologics, Inc in Seattle Washington, and will highlight the potential of CD74 targeted therapies in pediatric AML. See the abstract here.