Company Overview This presentation and the accompanying oral presentation contain "forward-looking" statements that are based on our management's beliefs and assumptions and on information currently available to management. Forward-looking statements include all statements other than statements of historical fact contained in this presentation, including information concerning our future financial performance, business plans and objectives, current and future clinical activities, timing, design and success ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from ________ to ________ Commission File Number: 001-38662 SUTRO BIOPHARMA, INC. (Exact Name of Registrant as Specified in its Charter) Delaware 47-0926186 (State ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-K (Mark One) ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2022 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number 001-38662 SUTRO BIOPHARMA, INC. (Exact Name of Registrant as Specified in Its Charter) (State or other jurisdiction of (I.R.S. Employer i ...

| --- | --- | --- | |---------------------------------------------------------------|-------|-------| | | | | | | | | | | | | | Company Overview November 2022 Sutro Biopharma NASDAQ: STRO | | | Forward-Looking Statements This presentation and the accompanying oral presentation contain "forward-looking" statements that are based on our management's beliefs and assumptions and on information currently available to management. Forward-looking statements include all statements other than statements of historica ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2022 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from ________ to ________ Commission File Number: 001-38662 SUTRO BIOPHARMA, INC. (Exact Name of Registrant as Specified in its Charter) Delaware 47-0926186 (State ...

| --- | --- | --- | |-----------------------------------------------------------|-------|-------| | | | | | | | | | | | | | Company Overview June 2022 Sutro Biopharma NASDAQ: STRO | | | Forward Looking Statements This presentation and the accompanying oral presentation contain "forward-looking" statements that are based on our management's beliefs and assumptions and on information currently available to management. Forward-looking statements include all statements other than statements of historical fact c ...

PART I. FINANCIAL INFORMATION [Financial Statements (Unaudited)](index=3&type=section&id=Item%201.%20Financial%20Statements%20%28Unaudited%29) Sutro Biopharma reported a net loss of **$39.1 million** for Q1 2022, an increase from **$30.4 million** in Q1 2021, due to decreased revenue and higher operating expenses [Condensed Balance Sheets](index=3&type=section&id=Condensed%20Balance%20Sheets) As of March 31, 2022, total assets decreased to **$303.7 million** from **$341.4 million** at year-end 2021, primarily due to reduced marketable securities and stockholders' equity Condensed Balance Sheet Highlights (in thousands) | Account | March 31, 2022 | December 31, 2021 | | :--- | :--- | :--- | | **Assets** | | | | Cash and cash equivalents | $28,901 | $30,414 | | Marketable securities (current & non-current) | $163,199 | $199,118 | | Total current assets | $228,742 | $218,515 | | Total assets | $303,675 | $341,408 | | **Liabilities & Stockholders' Equity** | | | | Total current liabilities | $38,760 | $41,736 | | Total liabilities | $83,303 | $88,844 | | Total stockholders' equity | $220,372 | $252,564 | | Total Liabilities and Stockholders' Equity | $303,675 | $341,408 | [Condensed Statements of Operations](index=4&type=section&id=Condensed%20Statements%20of%20Operations) For Q1 2022, revenues significantly decreased to **$5.9 million** from **$14.7 million** year-over-year, leading to a wider net loss of **$39.1 million** Statement of Operations Summary (in thousands, except per share data) | Metric | Q1 2022 | Q1 2021 | | :--- | :--- | :--- | | Revenues | $5,897 | $14,660 | | Research and development | $29,990 | $22,562 | | General and administrative | $15,039 | $11,107 | | Loss from operations | ($39,132) | ($19,009) | | Net loss | ($39,110) | ($30,359) | | Net loss per share, basic and diluted | ($0.84) | ($0.66) | [Condensed Statements of Comprehensive Loss](index=5&type=section&id=Condensed%20Statements%20of%20Comprehensive%20Loss) Comprehensive loss for Q1 2022 increased to **$39.9 million** from **$30.5 million** in Q1 2021, driven by a higher net loss and unrealized losses on securities Comprehensive Loss Summary (in thousands) | Metric | Q1 2022 | Q1 2021 | | :--- | :--- | :--- | | Net loss | $(39,110) | $(30,359) | | Unrealized loss on available-for-sale securities | $(838) | $(129) | | **Comprehensive loss** | **$(39,948)** | **$(30,488)** | [Condensed Statements of Stockholders' Equity](index=6&type=section&id=Condensed%20Statements%20of%20Stockholders%27%20Equity) Total stockholders' equity decreased by **$32.2 million** to **$220.4 million** as of March 31, 2022, primarily due to the net loss for the quarter - Stockholders' equity declined by **$32.2 million** during Q1 2022, mainly due to a net loss of **$39.1 million**[15](index=15&type=chunk) [Condensed Statements of Cash Flows](index=7&type=section&id=Condensed%20Statements%20of%20Cash%20Flows) Net cash used in operating activities was **$35.3 million** in Q1 2022, resulting in a **$1.5 million** net decrease in cash and equivalents Cash Flow Summary (in thousands) | Activity | Q1 2022 | Q1 2021 | | :--- | :--- | :--- | | Net cash used in operating activities | $(35,255) | $(30,430) | | Net cash provided by (used in) investing activities | $32,982 | $(121,730) | | Net cash provided by financing activities | $760 | $1,826 | | **Net decrease in cash, cash equivalents and restricted cash** | **$(1,513)** | **$(150,334)** | [Notes to Unaudited Condensed Financial Statements](index=8&type=section&id=Notes%20to%20Unaudited%20Condensed%20Financial%20Statements) The notes detail the company's accumulated deficit, liquidity, revenue sources, and the renegotiation of the Tasly License Agreement post-quarter end - The company has an accumulated deficit of **$372.5 million** as of March 31, 2022, but believes its unrestricted cash, cash equivalents, and marketable securities of **$192.1 million** are sufficient to fund operations for at least the next 12 months[23](index=23&type=chunk)[24](index=24&type=chunk)[25](index=25&type=chunk) Revenue by Collaborator (in thousands) | Collaborator | Q1 2022 | Q1 2021 | | :--- | :--- | :--- | | Bristol Myers Squibb Company ("BMS") | $2,165 | $1,239 | | Merck Sharp & Dohme Corporation ("Merck") | $1,064 | $11,883 | | EMD Serono | $1,897 | $220 | | Vaxcyte | $771 | $1,318 | | **Total revenue** | **$5,897** | **$14,660** | - The company did not recognize the **$40.0 million** upfront payment from the Tasly License Agreement as of March 31, 2022, because Tasly requested to renegotiate terms in February 2022[97](index=97&type=chunk) - Subsequent to the quarter end, on April 18, 2022, the Tasly agreement was amended, changing the upfront payment to **$25.0 million** with an additional **$15.0 million** in escrow contingent on regulatory milestones[128](index=128&type=chunk) [Management's Discussion and Analysis of Financial Condition and Results of Operations](index=26&type=section&id=Item%202.%20Management%27s%20Discussion%20and%20Analysis%20of%20Financial%20Condition%20and%20Results%20of%20Operations) Management attributes the Q1 2022 revenue decrease to lower Merck collaboration revenue and explains increased operating expenses due to higher headcount and clinical development activities - The company's two most advanced wholly-owned product candidates are STRO-002 for ovarian and endometrial cancers, and STRO-001 for B-cell malignancies[133](index=133&type=chunk) Financial Results Comparison (in thousands) | Metric | Q1 2022 | Q1 2021 | Change (%) | | :--- | :--- | :--- | :--- | | Revenues | $5,897 | $14,660 | (60)% | | Research and development | $29,990 | $22,562 | 33% | | General and administrative | $15,039 | $11,107 | 35% | | Loss from operations | $(39,132) | $(19,009) | 106% | - The decrease in revenue was primarily due to a **$10.8 million** decrease from Merck, related to the completion of performance obligations under the 2018 agreement[156](index=156&type=chunk) - As of March 31, 2022, the company had **$192.1 million** in cash, cash equivalents, and marketable securities, which is believed sufficient to fund operations for at least the next twelve months[162](index=162&type=chunk)[169](index=169&type=chunk) - The COVID-19 pandemic is causing increased costs and delays in material availability, though patient enrollment and treatment remain on track[141](index=141&type=chunk) [Quantitative and Qualitative Disclosures About Market Risk](index=35&type=section&id=Item%203.%20Quantitative%20and%20Qualitative%20Disclosures%20About%20Market%20Risk) The company is exposed to market risks, primarily interest rate sensitivities on its investment portfolio and equity price risk from its Vaxcyte common stock holding - The company's primary market risks are interest rate sensitivity and equity price risk from its investment in Vaxcyte common stock[185](index=185&type=chunk) - As of March 31, 2022, the company held **$37.7 million** in Vaxcyte common stock, where a hypothetical 10% decrease in market price would reduce fair value by **$3.8 million**[186](index=186&type=chunk)[187](index=187&type=chunk) - The company's outstanding debt of **$25.3 million** bears a floating interest rate, but a 100 basis point change would not materially impact interest expense[189](index=189&type=chunk) [Controls and Procedures](index=35&type=section&id=Item%204.%20Controls%20and%20Procedures) Management concluded that the company's disclosure controls and procedures were effective as of March 31, 2022, with no material changes in internal control over financial reporting - The CEO and CFO concluded that as of March 31, 2022, the company's disclosure controls and procedures were effective at a reasonable assurance level[191](index=191&type=chunk) - No changes in internal control over financial reporting occurred during Q1 2022 that materially affected, or are reasonably likely to materially affect, internal controls[192](index=192&type=chunk) PART II. OTHER INFORMATION [Legal Proceedings](index=36&type=section&id=Item%201.%20Legal%20Proceedings) The company is not currently a party to any legal proceedings that management believes would have a material adverse effect on its business - The company is not presently a party to any legal proceedings that would have a material adverse effect on its business[194](index=194&type=chunk) [Risk Factors](index=36&type=section&id=Item%201A.%20Risk%20Factors) The company outlines significant risks including its history of losses, dependence on early-stage product candidates, need for additional funding, and challenges with its unproven platform and manufacturing - The company has a history of significant losses (**$372.5 million** accumulated deficit as of March 31, 2022) and may never achieve profitability[197](index=197&type=chunk)[200](index=200&type=chunk) - The business is highly dependent on the success of its proprietary product candidates, STRO-001 and STRO-002, which are in early stages of clinical development[197](index=197&type=chunk)[217](index=217&type=chunk) - The COVID-19 pandemic is impacting the availability of routine materials, causing sourcing difficulties and modified manufacturing schedules, which could potentially delay clinical trials[197](index=197&type=chunk)[201](index=201&type=chunk)[205](index=205&type=chunk) - The company's approach is based on novel XpressCF® and XpressCF+® platforms, which are unproven and may not result in marketable products, as no cell-free platform product has FDA approval[223](index=223&type=chunk)[239](index=239&type=chunk) - The company relies on third-party manufacturers for components and faces risks related to their compliance, quality, and supply capacity, as well as risks in scaling its own internal manufacturing[201](index=201&type=chunk)[253](index=253&type=chunk) [Unregistered Sales of Equity Securities and Use of Proceeds](index=88&type=section&id=Item%202.%20Unregistered%20Sales%20of%20Equity%20Securities%20and%20Use%20of%20Proceeds) The company reported no unregistered sales of equity securities during the period - There were no unregistered sales of equity securities in the quarter[427](index=427&type=chunk) [Defaults Upon Senior Securities](index=88&type=section&id=Item%203.%20Defaults%20Upon%20Senior%20Securities) The company reported no defaults upon senior securities - There were no defaults upon senior securities[427](index=427&type=chunk) [Mine Safety Disclosures](index=88&type=section&id=Item%204.%20Mine%20Safety%20Disclosures) This item is not applicable to the company - Not applicable[428](index=428&type=chunk) [Other Information](index=88&type=section&id=Item%205.%20Other%20Information) The company reported no other information for the period - None[429](index=429&type=chunk) [Exhibits](index=89&type=section&id=Item%206.%20Exhibits) This section lists the exhibits filed with the Quarterly Report on Form 10-Q, including CEO and CFO certifications and Inline XBRL data files - The exhibits include certifications from the Principal Executive Officer and Principal Financial Officer pursuant to Sarbanes-Oxley Act Sections 302 and 906, as well as Inline XBRL documents[432](index=432&type=chunk)

| --- | --- | |-------|-------| | | | | | | Forward Looking Statements This presentation and the accompanying oral presentation contain "forward-looking" statements that are based on our management's beliefs and assumptions and on information currently available to management. Forward-looking statements include all statements other than statements of historical fact contained in this presentation, including information concerning our future financial performance, business plans and objectives, current and f ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-K (Mark One) ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2021 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number 001-38662 SUTRO BIOPHARMA, INC. (Exact Name of Registrant as Specified in Its Charter) Delaware 47-0926186 (State or other jurisdiction o ...

STRO-002 Clinical Trial Updates - Interim data from the dose expansion cohort of the STRO-002 Phase 1 study in advanced ovarian cancer showed a 333% objective response rate (ORR) in all 33 evaluable patients, unenriched for FolRα expression[52] - A higher response rate of 471% ORR was observed in patients starting at the 52 mg/kg dose level of STRO-002[52] - Exploratory analysis suggests that a Tumor Proportion Score (TPS) > 25% correlated with a higher response rate, demonstrating a 400% ORR (10/25) in patients at the 52 mg/kg starting dose[68, 76] - The company plans to initiate a pivotal trial in ovarian cancer by year-end 2022[13] - First patient dosed in endometrial cancer cohort in November 2021[13] - First patient dosed in bevacizumab combination trial in Q1 2022[13] STRO-001 Clinical Trial Updates - STRO-001 is undergoing Phase 1 dose escalation study with NHL update at ASH 2020[88] - As of October 2021, the last reported doses levels were of 50 mg/kg in the multiple myeloma (MM) cohort and 42 mg/kg in the non-Hodgkin's lymphoma (NHL) cohort[91] Financial Status - The company reported $2542 million in cash, cash equivalents, and marketable securities as of September 30, 2021[99] - Projected cash runway into 2H 2023, based on current business plans and assumptions[99] - Funding received from collaborators of approximately $434 million through September 30, 2021[99]