- Clarified NIH Criteria by amending the test related to the NIH Consensus Criteria Clinical Assessment (Modified version) throughout the protocol. - Added Consensus Clinical Assessment terminology. - Clarified that the TSS will be completed for all subjects in order to avoid confusion between subjects with or without cutaneous involvement and those for whom the eCRF may have been incorrectly completed. - Clarified that increases in CsA dosing should only be in the setting of serum levels which are below the therapeutic level. - Added “Relapse of underlying malignancy” to the Safety Endpoint and Subject Withdrawal and Replacement sections. - Clarified the time of randomization and assessment of study evaluations and treatments. - Increased allowed exposure to corticosteroids before the Baseline Visit from 3 days to 4 days. - Added information regarding the use of topical skin and ophthalmic corticosteroids as concomitant medication in order to reflect clinical practice as well as to control duration. - Clarified subject hospitalization, expedited reporting, and elective hospitalization. - Added information regarding the external DSMB. - Added information regarding Data Quality Assurance.

- Provided changes in sponsor signatories and to safety reporting centers in the US and Europe throughout the protocol. - Clarified that CsA treatment may be continuing, rather, than initiated, at the start of study treatment. - Revised the study synopsis consistent with revisions to the study exclusion criteria. - Clarified: -the inclusion of subjects with moderate or severe cGvHD as defined by the NIH Consensus Criteria. -exclusion criteria regarding the duration of previous treatment with systemic steroids for mild and moderate to severe cGvHD. -that subjects who have discontinued treatment with low absorption steroids or enema preparations prior to or at screening are still eligible for the study. -that subjects who have received DLI in the past are still eligible for the study. - Provided examples of prohibited TKIs, indicated that PUVA is prohibited during the study, and included tapering requirements for MMF. - Added TKI, PUVA, and UK to List of Abbreviations and Definition of Terms. - Clarified: -for subjects with aphakia, that if the eye with aphakia has no vision capabilities then the subject may be included in the study. -that the Screening Visit platelet count will be used for stratification of treatment arms. - Added quantity of blood to process during each treatment for subjects in the SoC + ECP treatment arm. - Updated drugs/therapies prohibited during the study based on revisions to exclusion criteria. - Removed inaccurate sentence regarding baseline and randomization timing from Section 6. 1. 2. - Clarified: -that for subjects randomized to SoC + ECP treatment arm, additional blood samples will be collected for hematocrit and hemoglobin tests, and samples will be sent to local laboratory to perform testing before ECP therapy. -that all visits should occur within ± 3 days of the scheduled visit including ECP therapy visits. -the start corticosteroid treatment with occurrencof Baseline Visit. - Corrected for readability

- Revised inclusion criteria for allowed dose of corticosteroids for cGvHD to be consistent with revised exclusion criteria. - Included new inclusion criteria for emphasis on the already existing 1.0 mg/kg corticosteroid dose at baseline study requirement. - Expanded the subject population by allowing subjects who develop cGvHD for up to 3 years after their transplant to be included. - Expanded the subject population to include a more common subject type by altering the requirement for allowed treatment for mild cGvHD in the exclusion criteria. - Revised exclusion criteria to allow a higher corticosteroid dose for moderate to severe cGvHD prior to baseline. - Allowed more time for early study logistics by revising the exclusion criteria. - Added information and instruction for the optional long-term 2-year follow-up. - Expanded the SoC treatment to include the use of either Tac or CsA. - Expanded the possible number of countries and study centers for the study. - Revised the study synopsis to be consistent with revisions to the body of the protocol. - Revised eligibility criteria to ease enrollment requirements. - Clarified method (using the instrument display or the manual calculation with rounding) for determining dose. - Added DSMB and Tac to the List of Abbreviations and Definition of Terms. - Phase corrected from 2b to Early phase 1 (Pilot)