Regulatory & Clinical Updates - A BLA amendment was filed in May 2020 to further support the favorable safety and tolerability profile of Vicinium[4, 5, 6] - The PPQ campaign is expected to begin in June 2020 to demonstrate analytical comparability[4, 7] - CHMP provided CMC advice on May 29, 2020, supporting a clear regulatory path forward in Europe, aligning with global standards issued by the ICH[4, 9] - The MAA for Vicinium is expected to be submitted to the EMA in early 2021, with potential approval anticipated in early 2022[9] - Phase III trial data shows a 40% complete response rate (CRR) at 3 months for CIS patients[47, 48] - 76% of patients are cystectomy-free for 3 years based on Phase III trial data[47, 48, 62] Financial Status - The company had cash and cash equivalents of $425 million as of March 31, 2020[13] - Net proceeds from the ATM facility were $19 million in 4Q 2019, $32 million in 1Q 2020, and an estimated $30 million in April/May 2020[13] - Approximately $26 million remains available on a $35 million ATM facility[13] Commercial Opportunity - The company estimates that approximately 1500 urologists treat 75% of BCG patients, allowing for efficient targeting[81, 97]

[PART I - FINANCIAL INFORMATION](index=4&type=section&id=PART%20I%20-%20FINANCIAL%20INFORMATION) [Item 1. Financial Statements](index=4&type=section&id=Item%201.%20Financial%20Statements.) Presents unaudited condensed consolidated financial statements for Sesen Bio, Inc., including Balance Sheets, Statements of Income, Changes in Stockholders' Equity, and Cash Flows Condensed Consolidated Balance Sheet (Unaudited, In thousands) | Account | March 31, 2020 | December 31, 2019 | | :--- | :--- | :--- | | **Assets** | | | | Cash and cash equivalents | $42,463 | $48,121 | | Total current assets | $44,883 | $54,447 | | Total Assets | $104,665 | $114,365 | | **Liabilities & Stockholders' Equity** | | | | Total current liabilities | $7,366 | $8,517 | | Contingent consideration | $66,320 | $120,020 | | Total Liabilities | $86,214 | $141,065 | | Total Stockholders' Equity (Deficit) | $18,451 | $(26,700) | Condensed Consolidated Statements of Operations (Unaudited, In thousands) | Account | Three Months Ended March 31, 2020 | Three Months Ended March 31, 2019 | | :--- | :--- | :--- | | Research and development | $8,867 | $4,686 | | General and administrative | $3,448 | $3,055 | | Change in fair value of contingent consideration | $(53,700) | $(1,000) | | **Income (Loss) from Operations** | **$41,385** | **$(6,741)** | | **Net Income (Loss)** | **$41,564** | **$(6,480)** | Condensed Consolidated Statements of Cash Flows (Unaudited, In thousands) | Account | Three Months Ended March 31, 2020 | Three Months Ended March 31, 2019 | | :--- | :--- | :--- | | Net Cash Used in Operating Activities | $(8,838) | $(7,992) | | Net Cash Provided by Financing Activities | $3,180 | $7 | | **Net Decrease in Cash, Cash Equivalents and Restricted Cash** | **$(5,658)** | **$(7,985)** | - The company is a late-stage clinical company focused on targeted fusion protein therapeutics (TFPTs) for cancer, with its lead product, **Vicinium®**, in a **Phase 3** trial for high-risk non-muscle invasive bladder cancer (NMIBC), and a **Biologics License Application (BLA)** initiated with the **FDA** under Rolling Review in December 2019[27](index=27&type=chunk) - As of March 31, 2020, the company had cash and cash equivalents of **$42.5 million**, which management concluded is not sufficient to fund operations for at least twelve months, raising **substantial doubt** about the company's ability to continue as a **going concern**[29](index=29&type=chunk)[31](index=31&type=chunk) - The fair value of contingent consideration liability decreased significantly from **$120.0 million** at year-end 2019 to **$66.3 million** as of March 31, 2020, with this **$53.7 million decrease** primarily due to significant increases in discount rates resulting from financial market volatility related to the COVID-19 pandemic[47](index=47&type=chunk)[48](index=48&type=chunk) [Item 2. Management's Discussion and Analysis of Financial Condition and Results of Operations](index=24&type=section&id=Item%202.%20Management%27s%20Discussion%20and%20Analysis%20of%20Financial%20Condition%20and%20Results%20of%20Operations.) Management discusses financial condition, operating results, liquidity, and critical accounting policies, highlighting progress of Vicinium and going concern doubt - The company initiated a **Biologics License Application (BLA)** for **Vicinium** under Rolling Review with the **FDA** in December 2019, with the final module (CMC) expected to be submitted in the **second half of 2020**, though potential disruptions from COVID-19 are noted[103](index=103&type=chunk) VISTA Trial Preliminary Efficacy Data (Pooled Cohorts 1 & 2, n=89) | Time Point | Complete Response Rate (95% CI) | | :--- | :--- | | 3-months | 40% (30%-51%) | | 6-months | 28% (19%-39%) | | 9-months | 21% (13%-31%) | | 12-months | 17% (10%-26%) | - The median Duration of Response (DoR) for patients in Cohorts 1 and 2 is **287 days**, and among patients who achieved a complete response at 3 months, **52%** remained disease-free for 12 months or longer[112](index=112&type=chunk) - The European Medicines Agency (**EMA**) provided clinical Scientific Advice, stating the existing data is sufficient to support a marketing authorization application (**MAA**), which the company expects to submit in **early 2021**[115](index=115&type=chunk) - Management does not believe its cash of **$42.5 million** as of March 31, 2020, is sufficient to fund operations for the next twelve months, leading to **substantial doubt** about its ability to continue as a **going concern**[123](index=123&type=chunk) Comparison of Operating Results (In thousands) | Account | Three Months Ended March 31, 2020 | Three Months Ended March 31, 2019 | Change (%) | | :--- | :--- | :--- | :--- | | Research and development | $8,867 | $4,686 | 89% | | General and administrative | $3,448 | $3,055 | 13% | | Change in fair value of contingent consideration | $(53,700) | $(1,000) | 5,270% | | **Net Income (Loss)** | **$41,564** | **$(6,480)** | **(741)%** | - The **$4.2 million increase** in **R&D expense** was primarily due to costs for technology transfer and manufacturing scale-up for commercial supply of Vicinium, while the **$53.7 million decrease** in the fair value of contingent consideration was due to higher discount rates from market volatility[133](index=133&type=chunk)[135](index=135&type=chunk) [Item 3. Quantitative and Qualitative Disclosures About Market Risk](index=38&type=section&id=Item%203.%20Quantitative%20and%20Qualitative%20Disclosures%20About%20Market%20Risk.) The company, as a smaller reporting entity, is not required to provide market risk disclosures - As a **smaller reporting company**, Sesen Bio is **not required** to provide quantitative and qualitative disclosures about market risk[159](index=159&type=chunk) [Item 4. Controls and Procedures](index=38&type=section&id=Item%204.%20Controls%20and%20Procedures.) Management concluded disclosure controls and procedures were effective as of March 31, 2020, with no material changes to internal controls - Management, including the CEO and CFO, concluded that the company's disclosure controls and procedures were **effective** at a reasonable assurance level as of **March 31, 2020**[160](index=160&type=chunk) - There were **no changes** in the company's **internal control over financial reporting** during the quarter ended March 31, 2020, that have materially affected, or are reasonably likely to materially affect, internal controls[162](index=162&type=chunk) [PART II - OTHER INFORMATION](index=39&type=section&id=PART%20II%20-%20OTHER%20INFORMATION) [Item 1. Legal Proceedings](index=39&type=section&id=Item%201.%20Legal%20Proceedings.) The company is not currently subject to any material legal proceedings - As of the filing date, the company is **not a party** to any **material legal proceedings**[165](index=165&type=chunk) [Item 1A. Risk Factors](index=39&type=section&id=Item%201A.%20Risk%20Factors.) Updates risk factors, emphasizing potential adverse impacts of the COVID-19 pandemic and stock market volatility on the business - A significant new risk factor is the **COVID-19 pandemic**, which could **adversely impact business operations**, including difficulties in raising capital, delays in regulatory interactions, and interruptions to manufacturing and commercialization activities[167](index=167&type=chunk) - The company warns that its **common stock price** may **fluctuate substantially** due to general market volatility, particularly in response to the **COVID-19 pandemic**, which could be unrelated to the company's operational performance[169](index=169&type=chunk) [Item 2. Unregistered Sales of Equity Securities and Use of Proceeds](index=39&type=section&id=Item%202.%20Unregistered%20Sales%20of%20Equity%20Securities%20and%20Use%20of%20Proceeds.) The company did not issue any unregistered equity securities during the three months ended March 31, 2020 - **No unregistered equity securities** were issued during the first quarter of 2020[170](index=170&type=chunk) [Item 3. Defaults Upon Senior Securities](index=40&type=section&id=Item%203.%20Defaults%20Upon%20Senior%20Securities.) This item is not applicable to the company for the reporting period - The company reports **no defaults** upon senior securities[172](index=172&type=chunk) [Item 4. Mine Safety Disclosures](index=40&type=section&id=Item%204.%20Mine%20Safety%20Disclosures.) This item is not applicable to the company - The company has **no mine safety disclosures** to report[172](index=172&type=chunk) [Item 5. Other Information](index=40&type=section&id=Item%205.%20Other%20Information.) The company reports no other information to disclose for this period - There was **no other information** to report for the quarter[172](index=172&type=chunk) [Item 6. Exhibits](index=41&type=section&id=Item%206.%20Exhibits.) Lists exhibits filed with the Quarterly Report on Form 10-Q, including corporate governance documents and CEO/CFO certifications - The report includes standard exhibits such as the **Certificate of Incorporation**, **By-laws**, and **certifications** from the Chief Executive Officer and Chief Financial Officer pursuant to the **Sarbanes-Oxley Act**[174](index=174&type=chunk)[175](index=175&type=chunk)[177](index=177&type=chunk)

Financial Data and Key Metrics Changes - The company finished Q1 2020 with approximately $42.5 million in cash and cash equivalents, which is deemed sufficient to fund strategic priorities into 2021 [50] - The company carries no debts, which is considered a strength in the current environment [52] Business Line Data and Key Metrics Changes - The company successfully completed the manufacturing of the pre-PPQ batch at Fuji, demonstrating meaningful progress for CMC comparability [14] - The pre-PPQ batch met all quality acceptance criteria, indicating a positive review on the ability to demonstrate analytical comparability during the Process Performance Qualification (PPQ) campaign [30][34] Market Data and Key Metrics Changes - The market research indicates that approximately 30% of urologists treat about 75% of non-muscle invasive bladder cancer patients, allowing for a focused sales force of roughly 40 to 50 representatives [43] - The company estimates that the peak sales in Europe will be higher than in the United States due to a larger patient population and higher incidence rates of bladder cancer [64] Company Strategy and Development Direction - The company aims to leverage digital and social media to reach caregivers and family members who influence treatment decisions, which is seen as an efficient and scalable commercial approach [46][47] - The company is planning to initiate a confirmatory trial around the time of U.S. approval, with a design to compare against standard care chemotherapeutic agents [77] Management's Comments on Operating Environment and Future Outlook - Management expressed confidence in the strong commercial opportunities supported by recent market research results, highlighting the differentiated mechanism of action of Vicinium [13] - The company remains on track to complete the BLA submission in the second half of 2020, with potential U.S. approval anticipated in the first half of 2021 [37] Other Important Information - The company has instituted a flexible work-from-home policy for all employees in Canada and the U.S., ensuring that internal operations continue at normal levels [10] - The company has received positive feedback from the European Medicines Agency (EMA) regarding the marketing authorization application for Vicinium, with no additional clinical trials requested [39] Q&A Session Summary Question: Can you walk us through the next steps regarding manufacturing? - The company has completed the pre-PPQ run at Fuji and the first PPQ run at Baxter, with plans to conduct three consecutive runs this summer at Fuji [57] Question: What additional analyses does the EMA require? - The EMA prefers controlled clinical trials with survival endpoints, contrasting with the FDA's focus on single-arm trials [60] Question: What is the market opportunity for non-muscle invasive bladder cancer in Europe? - The incidence of bladder cancer in Europe is estimated to be two to three times that of the U.S., indicating a significant market opportunity [64] Question: What are the expectations regarding prior authorizations and step edits from payers? - Payers are expected to have minimal step edits and prior authorizations, focusing on high-grade non-muscle invasive bladder cancer patients [70] Question: How does the company view the confirmatory trial's impact on market access? - A successful confirmatory trial is expected to improve global access and reimbursement opportunities in both the U.S. and Europe [80] Question: Are there significant differences in bladder cancer treatment between the U.S. and Europe? - Generally, treatment practices are similar, with both regions using BCG as the first-line standard of care [83]

Business Updates & Clinical Development - Patient enrollment in the VISTA trial was completed in March 2018, with all patients finishing treatment and data submitted to the FDA in December 2019[3] - The company anticipates finalizing the BLA submission in 2H 2020, following positive interactions with the FDA [3, 18] - EMA submission for Vicinium is expected in early 2021, with potential approval anticipated in early 2022 [19] Market Opportunity & Research - Market research indicates a large commercial opportunity for Vicinium, supported by a highly differentiated mechanism of action and clinical profile [5, 31] - In Q1 2020, market research showed high-prescribing urologists prefer the Vicinium profile [10] - Urologists would use a branded agent in approximately 80% of their high-risk, BCG-unresponsive patients [11] - The company estimates that approximately 1,500 urologists treat 75% of BCG patients, allowing for efficient commercial targeting [22, 101] Financial Status - As of March 31, 2020, the company's cash and cash equivalents totaled $42.5 million, sufficient to fund key strategic priorities into 2021 [29]

Product Development and Clinical Trials - The company is advancing targeted fusion protein therapeutics (TFPTs) for cancer treatment, with its most advanced product candidate, Vicinium, targeting high-risk NMIBC[268] - As of May 29, 2019, the complete response rate (CRR) for Cohort 1 (n=86) at 3 months was 39% (95% CI: 28%-50%) and at 12 months was 17% (95% CI: 10%-27%) in evaluable patients[268] - The median duration of response (DoR) for patients in Cohorts 1 and 2 combined (n=93) is 287 days, with 52% remaining disease-free for 12 months or longer after treatment[275] - The company estimates that over 75% of patients treated with Vicinium in the VISTA Trial will remain cystectomy-free at 2.5 years[277] - The median time to disease recurrence for patients in Cohort 3 (n=40) is 402 days (95% CI: 170-NE)[277] - 90% of all patients treated with Vicinium are estimated to remain progression-free for 2 years or more[277] - The company received Fast Track designation from the FDA for Vicinium in August 2018 and reached agreement on an accelerated approval pathway in June 2019[279] - The first full commercial-scale cGMP run for Vicinium was completed at Fujifilm in April 2019, supporting the ability to produce the drug substance for commercial purposes upon regulatory approval[282] - The company has deferred further development of Vicinium for the treatment of SCCHN and VB6-845d to focus on Vicinium for high-risk NMIBC[286] Financial Performance - As of December 31, 2019, the company had cash and cash equivalents of $48.1 million and a net working capital of $45.9 million[286] - The company incurred negative cash flows from operating activities of $37.5 million, $22.8 million, and $17.8 million for the years ended December 31, 2019, 2018, and 2017, respectively[286] - The net loss for 2019 was $107.5 million, compared to a net loss of $33.7 million in 2018, reflecting a 219% increase in losses[295] - Cash and cash equivalents as of December 31, 2019, were $48.1 million, with a net working capital of $45.9 million and an accumulated deficit of $293.5 million[302] - Negative cash flows from operating activities were $37.5 million in 2019, compared to $22.8 million in 2018[302] - The company raised $27.8 million in net proceeds from a public offering in June 2019, selling 20.4 million shares of common stock[302] - The company anticipates continued operating losses as it progresses through the Phase 3 VISTA Trial for Vicinium and seeks FDA marketing approval[302] - The company reported a net cash increase of $(2.3) million in 2019, compared to an increase of $35.8 million in 2018[308] Research and Development Expenses - Research and development expenses for Vicinium for the treatment of high-risk NMIBC were $16.0 million in 2019, up from $8.9 million in 2018 and $7.0 million in 2017, indicating a 79% increase year-over-year[290] - Total research and development expenses for the company were $24.7 million in 2019, compared to $14.1 million in 2018 and $12.5 million in 2017[290] - The company expects research and development expenses for Vicinium for the treatment of high-risk NMIBC to continue increasing in subsequent periods[288] - Research and development expenses increased to $24.7 million in 2019 from $14.1 million in 2018, a rise of $10.6 million or 75%[296] Operating Expenses and Losses - Total operating expenses surged to $108.5 million in 2019 from $34.5 million in 2018, an increase of $73.99 million or 214%[295] - The non-cash change in fair value of contingent consideration was $71.6 million in 2019, up from $8.8 million in 2018, representing a 714% increase[298] - General and administrative expenses rose to $12.2 million in 2019 from $11.6 million in 2018, an increase of $0.6 million or 5%[297] - The net loss for 2019 was $107.5 million, adjusted for non-cash items including a change in the fair value of contingent consideration of $71.6 million[309] Funding and Agreements - The company has received a total of $30.0 million in payments from Roche under the License Agreement, including a $7.5 million upfront payment and a $22.5 million milestone payment[284] - The company is entitled to receive up to an additional $240.0 million upon achieving specified regulatory, development, and commercial milestones from Roche[284] - The company has no committed external funding sources other than amounts payable under the License Agreement with Roche[307] Assets and Liabilities - The company has indefinite-lived intangible assets related to in-process research and development for Vicinium, which will be amortized upon product launch if approved[313] - Goodwill on the balance sheet, resulting from the Viventia Acquisition, was tested for impairment and found not to be impaired for the years ended December 31, 2019, 2018, and 2017[314] - Contingent consideration related to the Viventia Acquisition is measured at fair value and is subject to fluctuations based on future sales and milestones[315] Tax and Off-Balance Sheet Arrangements - The company did not have any uncertain tax positions as of December 31, 2019, and 2018[319] - There were no off-balance sheet arrangements during the periods presented[321]

Financial Data and Key Metrics Changes - The company ended 2019 with approximately $48 million in cash and cash equivalents, which is deemed sufficient to fund strategic priorities into 2021 [35] - The company has no debt and ended the year with 106.8 million shares of common stock outstanding, equating to $136 million on a fully diluted basis [35] Business Line Data and Key Metrics Changes - Vicinium is positioned to address a significant unmet need in bladder cancer treatment, with a projected $6 billion burden on payers in the U.S. alone for the year [8] - In Phase III data, 76% of patients were able to avoid radical cystectomy for at least three years, showcasing a strong clinical benefit [12] Market Data and Key Metrics Changes - Approximately 80,000 patients are diagnosed with bladder cancer each year in the U.S., with urologists managing the majority of treatment journeys [8] - Market research indicates that physicians prefer Vicinium over Keytruda for high-risk non-muscle invasive bladder cancer patients about 80% of the time [17] Company Strategy and Development Direction - The company aims to complete its Biologics License Application (BLA) submission this year, with a clear regulatory path forward based on recent FDA meetings [7][31] - A focused commercial model is planned, targeting approximately 1,500 urologists who prescribe the majority of treatments in this category [23] Management's Comments on Operating Environment and Future Outlook - Management expressed confidence in the regulatory path forward and the potential for a successful launch of Vicinium, emphasizing the strong advocacy from stakeholders [36] - The company has not experienced any business disruptions due to the COVID-19 pandemic and is executing risk mitigation strategies [45] Other Important Information - The company has partnered with Fuji and Baxter for manufacturing capabilities to meet global demand for Vicinium [32] - The company plans to initiate a confirmatory trial prior to approval, projecting possible approval in the first half of 2021 [51] Q&A Session Summary Question: Differences in Keytruda data for approval in the U.S. versus outside - Management noted a significant disparity in Keytruda's overall data, with a 41% complete response rate globally compared to roughly 31% in the U.S. [39] Question: Stability data for Vicinium's manufacturing and analytical comparability - Management outlined that the FDA will look for analytical release testing, biophysical characterization, forced degradation studies, and long-term stability studies [41] Question: Modifications due to the pandemic and status of confirmatory trial - Management confirmed that there are currently no significant regulatory or manufacturing risks due to COVID-19 and that the confirmatory trial is projected to start in the first half of 2021 [50][51]

seser b i o March 2020 Business Update March 16, 2020 NASDAQ: SESN For investor purposes only FORWARD-LOOKING STATEMENTS This presentation contains forward-looking statements that involve substantial risks and uncertainties. All statements, other than statements of historical facts, contained in this presentation, including statements regarding our strategy, future operations, clinical development of our protein therapies, future financial position, future revenues, projected costs, prospects, plans and obj ...

Regulatory & Clinical - Sesen Bio initiated its BLA submission for Vicinium under Rolling Review on December 6th, significantly de-risking the regulatory path to approval[12] - The FDA accepted Sesen's analytical comparability plan, potentially eliminating the need for additional clinical trials to support the BLA and commercialization of Vicinium[10, 145] - In a Phase III trial, Vicinium achieved a 40% complete response rate (CRR) at 3 months in CIS patients[54, 59] - 52% of CIS patients who had a complete response at 3 months remained disease-free for a total of 12 months after starting Vicinium treatment in Phase III trial[54, 59] - In Phase III trial, the median time to recurrence for papillary patients treated with Vicinium was 402 days[54, 59] Commercial & Financial - Sesen Bio had $57.9 million in cash and cash equivalents as of September 30, 2019, sufficient to fund key strategic priorities into 4Q 2020[8] - Approximately 84% of high-prescribing Urologists stated they would prescribe Vicinium to their patients after reviewing the data[119, 122] - The company estimates that the OUS opportunity for Vicinium is 2-3 times larger than the US market[136] Manufacturing & Pipeline - Vicinium is manufactured using a robust, industry-standard microbial expression system, reducing the risk of supply shortages and leading to a relatively low cost-of-goods[140] - Sesen Bio is exploring Vicinium in combination with AstraZeneca's anti-PD-LI, Imfinzi (durvalumab), in a Phase I study run by the National Cancer Institute[116, 117]

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) [X] QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2019 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: 001-36296 Sesen Bio, Inc. (Exact name of registrant as specified in its charter) Delaware 26-2025616 (Sta ...

seser i b O 3Q 2019 Business Update November 12, 2019 FORWARD-LOOKING STATEMENTS This presentation contains forward-looking statements that involve substantial risks and uncertainties. All statements, other than statements of historical facts, contained in this presentation, including statements regarding our strategy, future operations, clinical development of our protein therapies, timing or probability of regulatory approval, future financial position, future revenues, projected costs, prospects, plans a ...