Table 2.

T1D drug development at present.

Target pathways	Target	Limitations	Clinical status	References
Inhibition of T cell activation	Anti-CD3, anti-CD2, etc.	Broad suppression induces adverse events	Approved by FDA	[53, 54, 57]
B cell antagonists	Anti-CD20	Not universal or persistent	Approved in multiple AIDs	[58]
Cytokine antagonists	IL-1, TNF-α, etc.	Focus on the last, more advanced stages of illness pathogenesis rather than their earliest stages; recurrent treatment; off-target effects	Several being tested in phase 1,2 studies of stage 3 T1D patients	[59, 60]
Cytokine agonists	IL-2, etc.	Off-target effects; recurrent treatment	Being tested in phase 1, 2 studies of stage 3 T1D patients	[61]
Autoantigen therapies	Peptides, nanoparticles, etc.	Mostly disappointing results	Early clinical trials	[62]
Adoptive cell therapy	CAR/TCR-Treg, etc.	Challenging drug development	Preclinical and early phase 1 trials underway	[63, 64]
β cell regeneration	Islet β cells, pancreatic α cells, etc.	Current therapeutic medicines have limited β cell recovery efficiency	Being tested	[120]