CD19 and neoplasm: These 4-1BBL antibody fusion proteins provide signal 2 to 4-1BB-expressing T cells, either in cis by binding to CD19-expressing malignant B cells in combination with the CD20-TCB glofitamab [26] or in trans by binding to FAP-expressing tumor fibroblasts in combination with the CEA-TCB cibisatamab [27,28].