In our study, there were no differences in the percentages of Gr-1+CD11b+ myeloid cells or regulatory T cells in the spleens of myeloma-bearing mice treated with anti-PD-L1 plus anti-CTLA4 as compared to anti-PD-L1 plus other checkpoint antibodies (Additional file 3: Figure S3). Here, CTLA4 is linked to plasma cell myeloma.