Item 7.01 Regulation FD Disclosure.
On January 5, 2022, Sutro Biopharma, Inc. (the "Company") issued a press release
announcing additional data from its ongoing, Phase 1 study of STRO-002 in
patients with advanced ovarian cancer. The Company also hosted a live webcast
KOL discussion regarding the interim data on January 5, 2022 at 5:00 p.m.
Eastern Time. An archived webcast of the event will be available on the Investor
section of the company's website at ir.sutrobio.com for approximately 30 days.
A copy of the press release and clinical data presentation presented during the
webcast event are attached as Exhibits 99.1 and 99.2, respectively to this
Current Report on Form 8-K. The clinical data presentation will also be
available on the Company's website in the Events & Presentations section at
The information furnished in this Item 7.01, including Exhibits 99.1 and 99.2,
shall not be deemed "filed" for purposes of Section 18 of the Securities
Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to
the liabilities of that section, nor shall it be deemed incorporated by
reference into any other filing under the Exchange Act or the Securities Act of
1933, as amended, except as expressly set forth by specific reference in such a
Item 8.01 Other Events.
On January 5, 2022, the Company announced updated data from its ongoing Phase 1
clinical trial of STRO-002 in patients with ovarian cancer.
The dose-expansion cohort for ovarian cancer enrolled 44 patients, who had
experienced up to three prior lines of therapy. As of the interim data cutoff
date of November 8, 2021, 43 patients had been randomized into dose levels
starting at 4.3 mg/kg and 5.2 mg/kg, and one patient had not yet been dosed. 81%
of the patients were platinum-resistant, and 63% and 65% of the patients had
been treated previously with bevacizumab and PARP inhibitors, respectively. Of
the 43 patients, 33 had at least one post-baseline scan, and therefore were
evaluable for RECIST v1.1 responses. As of the interim data cutoff date, the
Best Overall Response ("BOR") for evaluable patients were as follows (N=33):
Seven patients had achieved partial responses ("PR"), which were confirmed with
at least two post-baseline scans.
Five patients had unconfirmed partial responses ("PRu")s, based on having
received only one post-baseline scan as of the interim data cutoff date. Their
next scheduled scan, subsequent to the interim data cutoff date, revealed the
following: Four PRs were confirmed and one patient was in stable disease ("SD").
An Objective Response Rate ("ORR") of 33% (11 PRs out of 33 patients) was
demonstrated in all evaluable patients, unenriched for FolR?-expression levels
at both dose levels.
14 total patients experienced SD and 8 patients had progressive disease ("PD").
Dose response was observed, with an ORR of 47% (8 PRs out of 17 patients) for
patients who started at the 5.2 mg/kg dose level, unenriched for biomarker
Higher FolR? expression levels calculated using tumor proportion scores ("TPS")
correlated with higher response rates. TPS has been identified as a potentially
appropriate scoring algorithm for STRO-002 with respect to the biomarker
enrichment strategy. Based on an exploratory cut-off of TPS > 25%, a 40% ORR (10
PRs out of 25 patients) was observed. TPS <=25% demonstrates 13% ORR. Based on
the Company's data, an enrichment approach of TPS > 25% FolR? expression may
enable treatment of about 70% of the advanced ovarian cancer patient population.
Safety signals from the 43 safety evaluable patients, at the 5.2 mg/kg and 4.3
mg/kg starting dose levels, were consistent with data from the dose-escalation
No new safety signals were observed in the dose-expansion cohort, including the
absence of keratopathy.
85.5% treatment emergent adverse events ("TEAEs") were Grade 1-2.
Neutropenia was the leading TEAE, resulting in treatment delay or dose
reduction. The majority of the cases of neutropenia were generally asymptomatic
and resolved with a one week dose delay or, in other cases, with standard
medical treatment, including the use of G-CSF.
There were limited observed cases of febrile neutropenia, including one Grade 5
event at the 5.2 mg/kg starting dose level and one Grade 3 event at the 4.3
mg/kg starting dose level. The trial protocol was subsequently updated to
require dose reduction for Grade 4 neutropenia.
Data from the STRO-002 dose-expansion cohort are expected to provide further
information to inform regulatory discussions and a global registration strategy.
This current report contains forward-looking statements within the meaning of
the "safe harbor" provisions of the Private Securities Litigation Reform Act of
1995, including, but not limited to, anticipated preclinical and clinical
development activities, timing of announcements of clinical results, potential
benefits of STRO-002 and the company's other product candidates and platform,
potential future milestone and royalty payments, and potential market
opportunities for STRO-002 and the company's other product candidates. All
statements other than statements of historical fact are statements that could be
deemed forward-looking statements. Although the company believes that the
expectations reflected in such forward-looking statements are reasonable, the
company cannot guarantee future events, results, actions, levels of activity,
performance or achievements, and the timing and results of biotechnology
development and potential regulatory approval is inherently uncertain.
Forward-looking statements are subject to risks and uncertainties that may cause
the company's actual activities or results to differ significantly from those
expressed in any forward-looking statement, including risks and uncertainties
related to the company's ability to advance its product candidates, the receipt
and timing of potential regulatory designations, approvals and commercialization
of product candidates, and the Company's ability to successfully leverage Fast
Track designation, the market size for the Company's product candidates to be
smaller than anticipated, the impact of the COVID-19 pandemic on the Company's
business, clinical trial sites, supply chain and manufacturing facilities, the
Company's ability to maintain and recognize the benefits of certain designations
received by product candidates, the timing and results of preclinical and
clinical trials, the company's ability to fund development activities and
achieve development goals, the company's ability to protect intellectual
property, the value of the Company's holdings of Vaxcyte common stock, and the
Company's commercial collaborations with third parties and other risks and
uncertainties described under the heading "Risk Factors" in the Company's most
recent Quarterly Report on Form 10-Q for the period ended September 30, 2021
filed with the Securities and Exchange Commission (SEC), and other reports as
filed with the SEC. The Company undertakes no obligation to publicly update any
forward-looking statement, whether written or oral, that may be made from time
to time, whether as a result of new information, future developments or
Item 9.01 Financial Statements and Exhibits.
Exhibit No. Description
99.1 Press release by Sutro Biopharma, Inc.
99.2 Clinical Data Presentation
104 Cover Page Interactive Data File (embedded within the Inline XBRL
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