Minor changes as per MHRA request to contraceptive use and addition of serum magnesium in biochemistry tests. PI’s to advise male participants about sperm conservation prior to treatment.

Added transformed follicular to DLBCL to inclusion criteria Updated RSI information and versions of IBs for all IMPs. Wording of PET-CT requirements clarified, where PET/CT was used replaced with PET-CT. Removed text instructions to take Flow sample at diagnosis as this is not part of trial procedures. Update to Adverse Events of Special Interest section 7.5.4 Update Appendix 7 with Atezolizumab IB v10 guidance for the Management of Atezolizumab specific adverse events.

References to data protection act removed throughout. Updates to trial procedures: • Screening PET-CT window extended from within 28 days of treatment to within 42 days from treatment. (Also updated in section 5.1) • Bone marrow at screening now optional, investigators discretion as to whether it should be performed. Should still be performed if screening lab values are lower than expected to confirm eligibility on basis of bone marrow involvement. (Also updated in section 5.1) • Correction to wording, where ‘registration’ was written and it should have read ‘randomisation’ to occur following successful completion of screening stage. • Flow Samples collection window extended, can be taken up to 72 hours prior to day 1 of cycles where sample is to be collected. Now in line with the Streck sample window for collection. (Also updated in section 8.2) • Removal of instruction to randomise 3 days prior to treatment, this was an error. Randomisation to occur within 14 days of treatment. • Physical exam and ECOG performance status. To be taken within 48 hours of IMP administration.

Updates to eligibility criteria: • CD20 +ve diffuse large B-cell lymphoma (including transformation of previous low-grade lymphoma and primary mediastinal B-cell lymphoma) • Sufficient diagnostic material is now preferable, not mandatory, and age of blocks is ‘ideally’ within 6 months. • Clarification that patients can have received more than two prior lines of treatment. • Correction to the text where incorrectly it has been stated that male patients should use ‘one form’ of highly effective contraception and then listed acceptable forms which came as sets of two. This should have read ‘two forms’, so is now in line with the Patient Information Sheet (also corrected in section 7.5.6). • Creatinine clearance exclusion values made clearer that values below 60ml/min would be excluded, even with normal creatinine result.

Updates to section 5.1- Screening procedures updated to include new instructions for the tumour block requirements. These should ‘ideally’ be taken within 6 months of enrolment, previously it was stated they ‘must be’ taken within 6 months of enrolment. Sending of local pathology reports on the blocks where available to HMDS. Updates to section 6.8- Dose delays and modifications for toxicity Haematological toxicity-guided adjustments for immunochemotherapy, if platelets fall below 75 x 109/L chemotherapy should be delayed. Previously this was below 100 x 109/L and has been changed to be in line with exclusion criteria screening levels.

Updates to section 9.2- Sample Size: • Removal of information about Case-Morgan design and inclusion of information relating to trial length. • Minor wording updates to the flow diagram to clarify analysis will be on experimental arm patients. Updates to 9.3 Statistical Analysis Plan (SAP): • Clarification of analysis populations, to now include ‘efficacy safety population’ Appendix 7 - Management of atezolizumab-specific adverse events, updated to include new information from Roche regarding Immune related Nephritis as a known side effect, and its recommended management.

Update to section 6.10- IMP storage so that it is in agreement with IB guidance. Update to Reference Safety Information: • New IB’s and locations of RSI information • Information to refer to the most up to date SmPC in place for the trials nIMP Updates to section 8.3- Translational Blood Samples. Expanding the Streck sample description so that it is as detailed as that of Flow samples in section 8.2

Update to RSI table – SmPC’s for Gemcitabine and Oxaliplatin, and Atezolizumab IB updated from previous version. Guidelines added for permitted uses of single site radiotherapy post cycles in sections 5.3 and 5.9