76 Research and Development Expenses Research and development expenses increased $50.3 million, or 23%, during the year ended December 31, 2022 as compared to 2021. The following table summarizes our research and development expenses for the periods indicated (in thousands): Year Ended December 31, 2022 vs 2021 Change 2022 2021 2020 Dollar Tarcocimab program expenses........................ $ 132,953 $ 137,849 $ 58,563 $ (4,896) KSI-501 program expenses............................. 6,964 4,529 1,573 2,435 ABC Platform and other program expenses.... 27,409 11,354 7,365 16,055 Payroll and personnel expenses ...................... 79,314 51,171 30,434 28,143 Facilities and other research and development expenses ....................................................... 20,951 12,437 9,454 8,514 Total research and development expenses .. $ 267,591 $ 217,340 $ 107,389 $ 50,251 Tarcocimab program expenses decreased $4.9 million during the year ended December 31, 2022 as compared to 2021, primarily driven by the maturation of the tarcocimab clinical program and timing of manufacturing activities. We expect to read out topline data in the third quarter of 2023 for our paired long-interval Phase 3 studies GLEAM and GLIMMER in DME, short-interval Phase 3 study DAYLIGHT in wet AMD and prevention and treatment Phase 3 study GLOW in NPDR without DME, which are fully enrolled and have been designed to broaden tarcocimab’s product labeling. KSI-501 program expenses increased $2.4 million during the year ended December 31, 2022 as compared to 2021, primarily due to manufacturing activities for KSI-501. ABC Platform external expenses increased $16.1 million during the year ended December 31, 2022 as compared to 2021, primarily driven by manufacturing runs to support research and development efforts for our pipeline. Payroll and personnel expenses increased $28.1 million during the year ended December 31, 2022 as compared to 2021, primarily due to stock-based compensation expense. We recorded stock-based compensation expense of $36.7 million during the year ended December 31, 2022 relating to the Kodiak 2021 Long-Term Performance Incentive Plan, or LTPIP, as compared to $9.0 million for the year ended December 31, 2021. Facilities and other research and development expenses increased $8.5 million during the year ended December 31, 2022 as compared to 2021, primarily due to expansion of our Palo Alto facilities and infrastructure, as well as incremental research efforts on our pipeline. General and Administrative Expenses General and administrative expenses increased $24.1 million, or 48%, during the year ended December 31, 2022 as compared to 2021, primarily driven by stock-based compensation expense. We recorded stock-based compensation expense of $28.4 million for the year ended December 31, 2022 relating to the LTPIP, as compared to $6.7 million for the year ended December 31, 2021. Interest Income Interest income increased $6.8 million during the year ended December 31, 2022 as compared to 2021, which was mainly attributable to interest income earned on marketable securities invested during 2022. Other Income (Expense), Net Other income (expense), net increased $0.7 million during the year ended December 31, 2022 as compared to 2021, which was mainly attributable to gain from settlement of foreign currency forward contracts. Comparison of the Fiscal Years Ended December 31, 2021 and 2020 For a comparison of our results of operations for the fiscal years ended December 31, 2021 and 2020, see “Part II, Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations” in our Annual Report on Form 10-K for the fiscal year ended December 31, 2021, filed with the SEC on March 1, 2022.