X0306 4 2019-05-23 0 0001709401 Rubius Therapeutics, Inc. RUBY 0001222012 AFEYAN NOUBAR C/O RUBIUS THERAPEUTICS, INC. 399 BINNEY STREET, SUITE 300 CAMBRIDGE MA 02139 1 0 1 0 Stock Option (Right to Buy) 16.27 2019-05-23 4 A 0 25000 0 A 2029-05-22 Common Stock 25000 25000 D This option shall vest in full on the earlier of (i) the one year anniversary of the grant date or (ii) the date of the next annual meeting of stockholders following the grant date, subject to the recipient's continued service. Exhibit 24 - Power of Attorney /s/ Joanne M. Protano, Attorney-in-Fact 2019-05-28