Nature of business and basis of presentation	3 Months Ended
Mar. 31, 2020
Nature of business and basis of presentation
Nature of business and basis of presentation	1. Nature of business and basis of presentation Mersana Therapeutics, Inc. is a clinical stage biopharmaceutical company focused on developing antibody drug conjugates (ADCs) that offer a clinically meaningful benefit for cancer patients with significant unmet need. The Company has leveraged 20 years of industry learning in the ADC field to develop proprietary and differentiated technology platforms that enable it to design ADCs to have improved efficacy, safety and tolerability relative to existing ADC therapies. The Company’s innovative platforms which include Dolaflexin and Dolasynthen, each delivering its DolaLock payload, as well as Immunosynthen, delivering a novel stimulator of interferon genes (STING) agonist, provide an efficient product engine that has enabled a robust discovery pipeline for the Company and its partners. The Company’s product candidates include XMT‑1536 and XMT-1592. XMT-1536, an ADC utilizing the Company’s Dolaflexin platform and targeting NaPi2b, an antigen broadly expressed in ovarian cancer and non-small cell lung cancer (NSCLC) adenocarcinoma is currently in the expansion portion of a Phase 1 study in patients with ovarian cancer and NSCLC adenocarcinoma. XMT-1592 uses one of the Company’s new platforms, Dolasynthen, and also targets NaPi2b. The Company filed an Investigational New Drug (IND) application in the first quarter of 2020, which was approved by the U.S. Food and Drug Administration (FDA). The Company remains on track to initiate the Phase 1 dose escalation study of XMT-1592 in the second quarter of 2020. The Company has incurred cumulative net losses since inception. For the three months ended March 31, 2020, the net loss was $16,926, compared to net income of $21,901 in the three months ended March 31, 2019. The difference year over year is primarily attributable to $39,965 in revenue that was recognized in the first quarter of 2019 as a result of the discontinuation of the partnership with Takeda in the first quarter of 2019. The Company expects to continue to incur operating losses for at least the next several years. As of March 31, 2020, the Company had an accumulated deficit of $209,300. The future success of the Company is dependent on, among other factors, its ability to identify and develop its product candidates, and ultimately upon its ability to attain profitable operations. The Company has devoted substantially all of its financial resources and efforts to research and development and general and administrative expense to support such research and development. Net losses and negative operating cash flows have had, and will continue to have, an adverse effect on the Company’s stockholders' equity and working capital. On April 7, 2020, the Company sold 8,938,599 and 1,962,000 shares of common stock at $5.59 per share and $7.74 per share, respectively, to raise gross proceeds of $65,153 through its at-the-market equity offering program (ATM). The Company believes that its currently available funds will be sufficient to fund the Company’s operations through at least the next twelve months from the issuance of this Quarterly Report on Form 10-Q. Management’s belief with respect to its ability to fund operations is based on estimates that are subject to risks and uncertainties. If actual results are different from management’s estimates, the Company may need to seek additional funding. The Company is subject to risks common to companies in the biotechnology industry, including but not limited to, the need for additional capital, risks of failure of preclinical and clinical studies, the need to obtain marketing approval and reimbursement for any drug product candidate that it may identify and develop, the need to successfully commercialize and gain market acceptance of its product candidates, dependence on key personnel, protection of proprietary technology, compliance with government regulations, development of technological innovations by competitors, reliance on third party manufacturers and the ability to transition from pilot-scale production to large-scale manufacturing of products. The Company’s unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (U.S. GAAP) and the rules and regulations of the Securities and Exchange Commission (SEC). Any reference in these notes to applicable guidance is meant to refer to the authoritative United States generally accepted accounting principles as found in the Accounting Standards Codification (ASC) and Accounting Standards Updates (ASU) of the Financial Accounting Standards Board (FASB). All dollar amounts, except per share data in the text and tables herein, are stated in thousands unless otherwise indicated. Certain information and footnote disclosures normally included in annual financial statements prepared in accordance with U.S. GAAP have been condensed or omitted from this report, as is permitted by such rules and regulations. Accordingly, these financial statements should be read in conjunction with the audited financial statements as of and for the year ended December 31, 2019 and the notes thereto, included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019 filed with the SEC on February 28, 2020. The unaudited condensed consolidated financial statements have been prepared on the same basis as the audited financial statements. In the opinion of the Company’s management, the accompanying unaudited condensed consolidated financial statements contain all adjustments that are necessary to present fairly the Company’s financial position as of March 31, 2020, the results of its operations for the three months ended March 31, 2020 and 2019, a statement of stockholders’ equity for the three months ended March 31, 2020 and 2019 and cash flows for the three months ended March 31, 2020 and 2019. Such adjustments are of a normal and recurring nature. The results for the three months ended March 31, 2020 are not necessarily indicative of the results for the year ending December 31, 2020, or for any future period.

1. Nature of business and basis of presentation

Mersana Therapeutics, Inc. is a clinical stage biopharmaceutical company focused on developing antibody drug conjugates (ADCs) that offer a clinically meaningful benefit for cancer patients with significant unmet need. The Company has leveraged 20 years of industry learning in the ADC field to develop proprietary and differentiated technology platforms that enable it to design ADCs to have improved efficacy, safety and tolerability relative to existing ADC therapies. The Company’s innovative platforms which include Dolaflexin and Dolasynthen, each delivering its DolaLock payload, as well as Immunosynthen, delivering a novel stimulator of interferon genes (STING) agonist, provide an efficient product engine that has enabled a robust discovery pipeline for the Company and its partners. The Company’s product candidates include XMT‑1536 and XMT-1592. XMT-1536, an ADC utilizing the Company’s Dolaflexin platform and targeting NaPi2b, an antigen broadly expressed in ovarian cancer and non-small cell lung cancer (NSCLC) adenocarcinoma is currently in the expansion portion of a Phase 1 study in patients with ovarian cancer and NSCLC adenocarcinoma. XMT-1592 uses one of the Company’s new platforms, Dolasynthen, and also targets NaPi2b. The Company filed an Investigational New Drug (IND) application in the first quarter of 2020, which was approved by the U.S. Food and Drug Administration (FDA). The Company remains on track to initiate the Phase 1 dose escalation study of XMT-1592 in the second quarter of 2020.

The Company has incurred cumulative net losses since inception. For the three months ended March 31, 2020, the net loss was $16,926, compared to net income of $21,901 in the three months ended March 31, 2019. The difference year over year is primarily attributable to $39,965 in revenue that was recognized in the first quarter of 2019 as a result of the discontinuation of the partnership with Takeda in the first quarter of 2019. The Company expects to continue to incur operating losses for at least the next several years. As of March 31, 2020, the Company had an accumulated deficit of $209,300. The future success of the Company is dependent on, among other factors, its ability to identify and develop its product candidates, and ultimately upon its ability to attain profitable operations. The Company has devoted substantially all of its financial resources and efforts to research and development and general and administrative expense to support such research and development. Net losses and negative operating cash flows have had, and will continue to have, an adverse effect on the Company’s stockholders' equity and working capital.

On April 7, 2020, the Company sold 8,938,599 and 1,962,000 shares of common stock at $5.59 per share and $7.74 per share, respectively, to raise gross proceeds of $65,153 through its at-the-market equity offering program (ATM). The Company believes that its currently available funds will be sufficient to fund the Company’s operations through at least the next twelve months from the issuance of this Quarterly Report on Form 10-Q. Management’s belief with respect to its ability to fund operations is based on estimates that are subject to risks and uncertainties. If actual results are different from management’s estimates, the Company may need to seek additional funding.

The Company is subject to risks common to companies in the biotechnology industry, including but not limited to, the need for additional capital, risks of failure of preclinical and clinical studies, the need to obtain marketing approval and reimbursement for any drug product candidate that it may identify and develop, the need to successfully commercialize and gain market acceptance of its product candidates, dependence on key personnel, protection of proprietary technology, compliance with government regulations, development of technological innovations by competitors, reliance on third party manufacturers and the ability to transition from pilot-scale production to large-scale manufacturing of products.

The Company’s unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (U.S. GAAP) and the rules and regulations of the Securities and Exchange Commission (SEC). Any reference in these notes to applicable guidance is meant to refer to the authoritative United States generally accepted accounting principles as found in the Accounting Standards Codification (ASC) and Accounting Standards Updates (ASU) of the Financial Accounting Standards Board (FASB). All dollar amounts, except per share data in the text and tables herein, are stated in thousands unless otherwise indicated. Certain information and footnote disclosures normally included in annual financial statements prepared in accordance with U.S. GAAP have been condensed or omitted from this report, as is permitted by such rules and regulations. Accordingly, these financial statements should be read in conjunction with the audited financial statements as of and for the year ended December 31, 2019 and the notes thereto, included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019 filed with the SEC on February 28, 2020.

The unaudited condensed consolidated financial statements have been prepared on the same basis as the audited financial statements. In the opinion of the Company’s management, the accompanying unaudited condensed consolidated financial statements contain all adjustments that are necessary to present fairly the Company’s financial position as of March 31, 2020, the results of its operations for the three months ended March 31, 2020 and 2019, a statement of stockholders’ equity for the three months ended March 31, 2020 and 2019 and cash flows for the three months ended March 31, 2020 and 2019. Such adjustments are of a normal and recurring nature. The results for the three months ended March 31, 2020 are not necessarily indicative of the results for the year ending December 31, 2020, or for any future period.