The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities as of the date of the condensed consolidated financial statements, and the reported amounts of expenses during the reporting periods. Significant estimates and assumptions reflected in these condensed consolidated financial statements include, but are not limited to, the accrual of research and development expenses and the valuation of stock-based awards. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Actual results could differ from the Company’s estimates.

Marketable debt securities consist of debt investments with original maturities greater than ninety days. The Company has classified its debt investments with maturities beyond one year as short term, based on their highly liquid nature and because such marketable debt securities represent the investment of cash that is available for current operations. The Company classifies its marketable debt securities as available-for-sale. Accordingly, these investments are recorded at fair value, which is based on quoted market prices. When the fair value is below the amortized cost the amount of the expected credit loss is estimated. The credit-related impairment amount is recognized in net income; the remaining impairment amount and unrealized gains are reported as a component of accumulated other comprehensive income in stockholders’ equity. Credit losses are recognized through the use of an allowance for credit losses account and subsequent improvements in expected credit losses are recognized as a reversal of the allowance account. If the Company has the intent to sell the security or it is more likely than not that the Company will be required to sell the security prior to recovery of its amortized cost basis, the allowance for credit loss is written off and the excess of the amortized cost basis of the asset over its fair value is recorded in net income.

Basic net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted average number of common shares outstanding for the period. Diluted net loss per share attributable to common stockholders is computed by dividing the diluted net loss attributable to common stockholders by the weighted average number of common shares, including potential dilutive common shares assuming the dilutive effect of outstanding stock options and unvested restricted common shares, as determined using the treasury stock method. For periods in which the Company has reported net losses, diluted net loss per common share attributable to common stockholders is the same as basic net loss per common share attributable to common stockholders, since dilutive common shares are not assumed to have been issued if their effect is antidilutive.

The Company excluded the following common stock equivalents, outstanding as of March 31, 2020 and 2019, from the computation of diluted net loss per share for the three months ended March 31, 2020 and 2019 because they had an anti-dilutive impact due to the net loss incurred for the periods:

	As of March 31,
	2020		2019
Options to purchase common stock		3,945,647		6,663,162
Unvested restricted common stock		40,766		351,371
		3,986,413		7,014,533

The Company is subject to risks and uncertainties as a result of the COVID-19 pandemic. The extent of the impact of the COVID-19 pandemic on the Company's business is highly uncertain and difficult to predict, as the response to the pandemic is in its incipient stages and information is rapidly evolving. Capital markets and economies worldwide have also been negatively impacted by the COVID-19 pandemic, and it is possible that it could cause a local and/or global economic recession. Such economic disruption could have a material adverse effect on the Company’s business. Policymakers around the globe have responded with fiscal policy actions to support the healthcare industry and economy as a whole. The magnitude and overall effectiveness of these actions remains uncertain.

The severity of the impact of the COVID-19 pandemic on the Company's business will depend on a number of factors, including, but not limited to, the duration and severity of the pandemic, all of which are uncertain and cannot be predicted. The Company is required to have a net cash balance of at least $30,000,000 at the closing of the merger as a condition to Chondrial’s obligation to consummate the merger. For purposes of the merger agreement, net cash is subject to certain reductions, including, without limitation, accounts payable, accrued expenses (except those related to the merger), current liabilities payable in cash, unpaid expenses related to the merger and certain other unpaid obligations, including outstanding lease obligations. The liability with regards to the Company’s outstanding lease obligations is a large component of the Company’s net cash and COVID-19 has created uncertainties surrounding our ability to take the steps necessary to sublease or negotiate a buy-out of our existing leases. In the event that the Company’s net cash falls below this threshold, a condition to the Chondrial’s obligation to consummate the merger will fail to be satisfied and Chondrial will have the right to terminate the merger agreement at an outside date of September 17, 2020 (subject to extension as provided in the merger agreement) if the Company’s net cash continues to be lower than the $30,000,000 threshold. As of the date of issuance of these condensed consolidated financial statements, the extent to which the COVID-19 pandemic may materially impact the Company's financial condition, liquidity, or results of operations is uncertain.

In June 2016 the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The FASB subsequently issued amendments to ASU 2016-13, which have the same effective date and transition date of January 1, 2020. This standard requires entities to estimate an expected lifetime credit loss on financial assets ranging from short-term trade accounts receivable to long-term financings and report credit losses using an expected losses model rather than the incurred losses model that was previously used, and establishes additional disclosures related to credit risks. For available-for-sale debt securities with unrealized losses, the standard now requires allowances to be recorded instead of reducing the amortized cost of the investment. This standard limits the amount of credit losses to be recognized for available-for-sale debt securities to the amount by which carrying value exceeds fair value and requires the reversal of previously recognized credit losses if fair value increases.

This standard became effective for the Company on January 1, 2020, and based on the composition of the Company’s marketable debt securities, current economic conditions and historical credit loss activity, the adoption of this standard did not have a material impact on the Company’s condensed consolidated financial statements and related disclosures.

In August 2018 the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement. This standard modifies certain disclosure requirements on fair value measurements. This standard became effective for the Company on January 1, 2020. The adoption of this standard did not have a material impact on the Company’s disclosures.