X0306 4 2021-02-16 0 0001645460 Cue Biopharma, Inc. CUE 0001571862 Pienta Kenneth C/O CUE BIOPHARMA, INC. 21 ERIE STREET CAMBRIDGE MA 02139 0 1 0 0 Chief Medical Officer Common Stock 2021-02-16 4 M 0 16000 2.86 A 18000 D Common Stock 2021-02-16 4 S 0 16000 15.1514 D 2000 D Common Stock 2021-02-17 4 M 0 1280 2.86 A 3280 D Common Stock 2021-02-17 4 M 0 2994 5.00 A 6274 D Common Stock 2021-02-17 4 S 0 4274 15.055 D 2000 D Stock Option (right to buy) 2.86 2021-02-16 4 M 0 16000 0.00 D 2023-11-16 Common Stock 16000 1280 D Stock Option (right to buy) 2.86 2021-02-17 4 M 0 1280 0.00 D 2023-11-16 Common Stock 1280 0 D Stock Option (right to buy) 5.00 2021-02-17 4 M 0 2994 0.00 D 2024-04-17 Common Stock 2994 147006 D The transactions reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on August 20, 2020. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $15.06 to $15.60, inclusive. The reporting person undertakes to provide to Cue Biopharma, Inc., any security holder of Cue Biopharma, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote (2) to this Form 4. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $15.00 to $15.20, inclusive. The reporting person undertakes to provide to Cue Biopharma, Inc., any security holder of Cue Biopharma, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote (3) to this Form 4. The option, representing a right to purchase a total of 20,000 shares, became exercisable in full on November 16, 2017. The option, representing a right to purchase a total of 150,000 shares, vests in four equal annual installments beginning December 31, 2017. /s/ Kenneth Pienta by Colin Sandercock, attorney-in-fact 2021-02-18