SLC34A2 and neoplasm: However, further investigation of this hypothesis is warranted due to the recent discontinuation of upifitamab rilsodotin targeting sodium-dependent phosphate transport protein 2B (SLC34A2/NaPi2b), which is expressed in both tumor and normal tissues, such as the lungs, bronchus, and kidneys, due to the lack of efficacy at phase Ib doses, as well as on-target, off-tumor toxicities (as discussed below) observed with several clinical-stage ADCs [24,25,26].