APLS 2017 Annual Report

80 obligation related to the future issuance of our common stock and therefore no common stock derivative liability on the consolidated balance sheets. Interest Income (Expense), Net Interest income (expense), net was an expense of $0.1 million for the year ended December 31, 2017, a decrease of $0.2 million, compared to $0.1 million of interest income for the year ended December 31, 2016. The interest expense incurred in 2017 was primarily attributable to interest expense incurred on our long-term debt. The interest income earned in 2016 and 2017 relates to interest earned from cash equivalents and cash equivalents. Other Income, Net Other income, net remained relatively stable for the year ended December 31, 2017 as compared to the year ended December 31, 2016. In both periods, other income was primarily attributable to rent charged to two related entities while other expense was primarily related to corporate franchise taxes and fees. Comparison of Years Ended December 31, 2015 and 2016 The following table summarizes our results of operations for the years ended December 31, 2015 and 2016, together with the dollar increase or decrease and percentage change in those items: Year Ended December 31, Change Change 2015 2016 $ % Operating expenses: Research and development $ 13,730,311 $ 22,978,599 $ 9,248,288 67.4% Cost of acquired in process research and development 26,486,000 — (26,486,000) (100.0) General and administrative 6,356,782 4,303,743 (2,053,039) (32.3) Operating loss (46,573,093) (27,282,342) 19,290,751 (41.4) Interest income, net 50,853 135,309 84,456 166.1 Other income, net 6,284 22,396 16,112 256.4 Net loss and comprehensive loss $ (46,515,956) $ (27,124,637) $ 19,391,319 (41.7) Research and Development Expenses The following table summarizes our research and development expenses incurred during the years ended December 31, 2015 and 2016, together with the dollar increase or decrease and percentage change in those items: Year Ended December 31, Change Change 2015 2016 $ % Clinical trial costs $ 6,926,701 $ 11,486,499 $ 4,559,798 65.8% Contract manufacturing 1,969,963 5,098,538 3,128,575 158.8 Pre-clinical study expenses 3,466,671 3,431,482 (35,189) (1.0) Compensation and related personnel costs 1,160,379 1,989,164 828,785 71.4 Other research and development costs 206,597 972,916 766,319 370.9 Total research and development expenses $ 13,730,311 $ 22,978,599 $ 9,248,288 67.4 Research and development expenses increased by $9.2 million to $23.0 million for the year ended December 31, 2016 from $13.7 million for the year ended December 31, 2015, an increase of 67.4%. The increase was attributable to an increase of $4.6 million in clinical trial costs, an increase of $3.1 million in formulation and manufacturing expenses, an increase of $0.8 million in employee related costs as a result of hiring additional personnel and an increase of $0.7 million related to other research and development costs for supporting activities.