91 ITEM 6. SELECTED CONSOLIDATED FINANCIAL DATA You should read the selected historical financial data below in conjunction with the section titled “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and the consolidated financial statements and related notes included elsewhere in this Annual Report on Form 10-K. The selected financial data set forth below is derived from our audited consolidated financial statements and may not be indicative of future operating results. Year Ended December 31, 2018 2017 2016 (in thousands, except share and per share data) Consolidated Statements of Operations Data: Operating expenses Research and development .................................................................. $ 18,793 $ 22,022 $ 14,053 General and administrative.................................................................. 7,581 3,499 3,098 Total operating expenses................................................................ 26,374 25,521 17,151 Loss from operations................................................................................. (26,374) (25,521) (17,151) Interest expense ................................................................................... (5,519) (1,185) (6) Other income (expense), net................................................................ (4,071) (1,230) 25 Loss on extinguishment of debt........................................................... (5,479) — — Net loss and comprehensive loss .............................................................. $ (41,443) $ (27,936) $ (17,132) Net loss per share attributable to common stockholders, basic and diluted..................................................................................... $ (2.77) $ (3.72) $ (2.38) Weighted-average shares outstanding used in computing net loss per share attributable to common stockholders, basic and diluted......... 14,976,515 7,515,336 7,211,360 As of December 31, 2018 2017 2016 (in thousands) Consolidated Balance Sheet Data: Cash and cash equivalents......................................................................... $ 88,254 $ 1,395 $ 9,622 Working capital......................................................................................... 85,623 (7,563) 7,682 Total assets................................................................................................ 92,189 3,244 12,114 Total liabilities .......................................................................................... 5,356 21,965 3,180 Accumulated deficit .................................................................................. (110,766) (69,323) (41,387) Total stockholders’ equity (deficit)........................................................... 86,833 (68,738) (41,083)