DEVELOPING THE NEXT GENERATION of immuno-oncology therapeutics w w w.phiopharma.com I Ticker: PHIO (NASDAQ) September 2021 Forward Looking Statements This presentation contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Words such as "believes," "anticipates," "plans," "expects," "indicates," "will," "intends," "potential," "suggests" and similar expressions are intended to identify forward-looking statements. These statements are based on Phio Pha ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 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: 001-36304 Phio Pharmaceuticals Corp. (Exact name of registrant as specified in its charter) Delaware 45-3215903 (State of inc ...

Part I - Financial Information [Financial Statements (Unaudited)](index=4&type=section&id=Item%201%20Financial%20Statements%20(Unaudited)) Phio Pharmaceuticals reported an increased net loss for Q1 2021, primarily due to higher R&D expenses, while significantly strengthening its balance sheet through substantial financing activities [Condensed Consolidated Balance Sheets](index=4&type=section&id=Condensed%20Consolidated%20Balance%20Sheets) As of March 31, 2021, total assets significantly increased to **$33.9 million**, primarily driven by a rise in cash, while stockholders' equity more than doubled due to financing activities Condensed Consolidated Balance Sheets (in thousands) | | March 31, 2021 | December 31, 2020 | | :--- | :--- | :--- | | **Assets** | | | | Cash | $32,695 | $14,244 | | Total current assets | $33,322 | $15,164 | | **Total assets** | **$33,856** | **$15,739** | | **Liabilities & Stockholders' Equity** | | | | Total current liabilities | $2,191 | $2,196 | | Total liabilities | $2,456 | $2,722 | | Total stockholders' equity | $31,400 | $13,017 | | **Total liabilities and stockholders' equity** | **$33,856** | **$15,739** | [Condensed Consolidated Statements of Operations](index=5&type=section&id=Condensed%20Consolidated%20Statements%20of%20Operations) For Q1 2021, the company reported a net loss of **$3.4 million**, an increase from the prior year, primarily due to a significant rise in Research and Development expenses Condensed Consolidated Statements of Operations (in thousands, except per share data) | | Three Months Ended March 31, 2021 | Three Months Ended March 31, 2020 | | :--- | :--- | :--- | | Research and development | $2,621 | $1,218 | | General and administrative | $1,017 | $1,138 | | **Total operating expenses** | **$3,638** | **$2,356** | | Operating loss | $(3,638) | $(2,356) | | Gain on extinguishment of debt | $233 | $– | | **Net loss** | **$(3,407)** | **$(2,351)** | | Net loss per common share (Basic and diluted) | $(0.32) | $(1.33) | [Condensed Consolidated Statements of Stockholders' Equity](index=6&type=section&id=Condensed%20Consolidated%20Statements%20of%20Stockholders'%20Equity) Stockholders' equity significantly increased to **$31.4 million** by March 31, 2021, primarily driven by substantial net proceeds from private placements, direct offerings, and warrant exercises - Total stockholders' equity increased from **$13.0 million** to **$31.4 million** in Q1 2021[15](index=15&type=chunk) - The company raised net proceeds of **$12.7 million** from a private placement and **$6.9 million** from a registered direct offering[15](index=15&type=chunk) - Net proceeds from the exercise of warrants amounted to **$2.1 million** during the quarter[15](index=15&type=chunk) [Condensed Consolidated Statements of Cash Flows](index=7&type=section&id=Condensed%20Consolidated%20Statements%20of%20Cash%20Flows) Net cash used in operating activities was **$3.0 million** for Q1 2021, offset by **$21.5 million** in net cash from financing activities, resulting in a **$18.5 million** net increase in cash Condensed Consolidated Statements of Cash Flows (in thousands) | | Three Months Ended March 31, 2021 | Three Months Ended March 31, 2020 | | :--- | :--- | :--- | | Net cash used in operating activities | $(3,033) | $(2,176) | | Net cash used in investing activities | $(6) | $(10) | | Net cash provided by financing activities | $21,490 | $8,536 | | **Net increase in cash and restricted cash** | **$18,451** | **$6,350** | | Cash and restricted cash at end of period | $32,745 | $13,334 | [Notes to Condensed Consolidated Financial Statements](index=8&type=section&id=Notes%20to%20Condensed%20Consolidated%20Financial%20Statements) The notes detail the company's immuno-oncology operations, its belief in sufficient cash for the next 12 months, the forgiveness of its PPP loan, and significant equity financing activities - The company is a biotechnology firm developing immuno-oncology therapeutics based on its self-delivering RNAi (INTASYL™) platform[22](index=22&type=chunk) - Management believes existing cash is sufficient to fund operations for at least the next 12 months from the report's release date[44](index=44&type=chunk) - In February 2021, the company's PPP loan of **$231,252** was fully forgiven, resulting in a gain on debt extinguishment of **$233,000**[52](index=52&type=chunk) - The company completed a private placement in January 2021 and a registered direct offering in February 2021, raising net proceeds of **$12.7 million** and **$6.9 million**, respectively[53](index=53&type=chunk)[54](index=54&type=chunk) [Management's Discussion and Analysis of Financial Condition and Results of Operations](index=17&type=section&id=Item%202%20Management's%20Discussion%20and%20Analysis%20of%20Financial%20Condition%20and%20Results%20of%20Operations) Management discusses the company's immuno-oncology platform and lead candidate PH-762, noting an increased operating loss driven by R&D expenses, yet significantly improved liquidity from financing activities [Overview](index=17&type=section&id=Overview) Phio is a biotechnology company developing immuno-oncology therapeutics using its INTASYL™ platform, with lead candidate PH-762 advancing towards clinical trials for direct therapeutic use and in collaboration with AgonOx - The company's development efforts are based on its self-delivering RNAi (INTASYL™) therapeutic platform, which does not require a delivery vehicle to penetrate tissues and cells[75](index=75&type=chunk)[76](index=76&type=chunk) - Lead product candidate PH-762 targets the checkpoint protein PD-1, with a clinical study for advanced melanoma expected to start in **Q4 2021**[82](index=82&type=chunk)[91](index=91&type=chunk) - The company entered a clinical development collaboration with AgonOx to develop T cell-based therapies using PH-762, with regulatory submission planned for **Q3 2021**[84](index=84&type=chunk) [Results of Operations](index=22&type=section&id=Results%20of%20Operations) Operating loss for Q1 2021 increased to **$3.6 million**, primarily driven by a **115%** rise in R&D expenses for clinical trial preparation, partially offset by lower G&A expenses and increased other income from PPP loan forgiveness Operating Expenses Comparison (in thousands) | Description | Q1 2021 | Q1 2020 | Dollar Change | | :--- | :--- | :--- | :--- | | Research and development | $2,621 | $1,218 | $1,403 | | General and administrative | $1,017 | $1,138 | $(121) | | **Total operating expenses** | **$3,638** | **$2,356** | **$1,282** | - The **115%** increase in R&D expenses was primarily due to manufacturing costs and fees for preclinical studies supporting the planned clinical trials for PH-762[107](index=107&type=chunk) - Other income increased by **$226,000** compared to the prior year, primarily due to the full forgiveness of the Company's PPP loan[110](index=110&type=chunk) [Liquidity and Capital Resources](index=23&type=section&id=Liquidity%20and%20Capital%20Resources) The company's cash position significantly increased to **$32.7 million** by March 31, 2021, driven by **$21.5 million** in net cash from financing activities, which management believes is sufficient for at least the next 12 months - The company believes its existing cash of **$32.7 million** at March 31, 2021, is sufficient to fund operations for at least the next 12 months[111](index=111&type=chunk)[113](index=113&type=chunk) Cash Flow Summary (in thousands) | | Three Months Ended March 31, 2021 | Three Months Ended March 31, 2020 | | :--- | :--- | :--- | | Net cash used in operating activities | $(3,033) | $(2,176) | | Net cash provided by financing activities | $21,490 | $8,536 | | **Net increase in cash and restricted cash** | **$18,451** | **$6,350** | - The increase in cash from financing activities was primarily due to net proceeds from capital raise activities and warrant exercises[117](index=117&type=chunk) [Quantitative and Qualitative Disclosures About Market Risk](index=24&type=section&id=Item%203%20Quantitative%20and%20Qualitative%20Disclosures%20About%20Market%20Risk) As a smaller reporting company, Phio Pharmaceuticals is not required to provide information for this item - The company is a smaller reporting company and is not required to provide this information[119](index=119&type=chunk) [Controls and Procedures](index=25&type=section&id=Item%204%20Controls%20and%20Procedures) Management concluded that disclosure controls and procedures were effective as of March 31, 2021, with no material changes to internal control over financial reporting during the quarter - Management, including the CEO and Principal Accounting Officer, concluded that the company's disclosure controls and procedures were effective as of March 31, 2021[121](index=121&type=chunk) - No changes in internal control over financial reporting occurred during the quarter that materially affected, or are reasonably likely to materially affect, internal controls[122](index=122&type=chunk) Part II - Other Information [Legal Proceedings](index=26&type=section&id=Item%201%20Legal%20Proceedings) The company reports that it is not currently a party to any material legal proceedings - There are no material legal proceedings at this time[125](index=125&type=chunk) [Risk Factors](index=26&type=section&id=Item%201A%20Risk%20Factors) This section directs readers to the detailed risk factors disclosed in the company's Annual Report on Form 10-K for the year ended December 31, 2020 - The report refers to the risk factors section in the Annual Report on Form 10-K for the year ended December 31, 2020[126](index=126&type=chunk) [Unregistered Sales of Equity Securities and Use of Proceeds](index=26&type=section&id=Item%202%20Unregistered%20Sales%20of%20Equity%20Securities%20and%20Use%20of%20Proceeds) The company reports no sales or issues of unregistered securities that have not been previously disclosed in a Current Report on Form 8-K - No sales or issues of unregistered securities occurred that have not previously been disclosed[127](index=127&type=chunk)[132](index=132&type=chunk) [Defaults Upon Senior Securities](index=26&type=section&id=Item%203%20Defaults%20Upon%20Senior%20Securities) The company reports no defaults upon senior securities - None[127](index=127&type=chunk) [Mine Safety Disclosures](index=26&type=section&id=Item%204%20Mine%20Safety%20Disclosures) This item is not applicable to the company - Not applicable[128](index=128&type=chunk) [Other Information](index=26&type=section&id=Item%205%20Other%20Information) The company reports no other information for this item - None[129](index=129&type=chunk) [Exhibits](index=26&type=section&id=Item%206%20Exhibits) This section provides an index of the exhibits filed with the Form 10-Q, including Sarbanes-Oxley certifications and XBRL data files - Lists exhibits filed with the report, including Sarbanes-Oxley certifications (31.1, 32.1) and XBRL financial data (101)[131](index=131&type=chunk)

Table of Contents 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, 2020 Or (508) 767-3861 ☐ 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 001-36304 PHIO PHARMACEUTICALS CORP. (Exact name of registrant as specified in its charter) (State or ot ...

DEVELOPING THE NEXT GENERATION of immuno-oncology therapeutics www.phiopharma.com I Ticker: PHIO (NASDAQ) January 2020 Forward Looking Statements This presentation contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Words such as "believes," "anticipates," "plans," "expects," "indicates," "will," "intends," "potential," "suggests" and similar expressions are intended to identify forward-looking statements. These statements are based on Phio Pharmac ...

DEVELOPING THE NEXT GENERATION of immuno-oncology therapeutics September 2019 www.phiopharma.com I Ticker: PHIO (NASDAQ) Forward Looking Statements This presentation contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Words such as "believes," "anticipates," "plans," "expects," "indicates," "will," "intends," "potential," "suggests" and similar expressions are intended to identify forward-looking statements. These statements are based on Phio Pharm ...