A novel variant of t-PA resistant to plasminogen activator inhibitor-1; expression in CHO cells based on In Silico experiments

Resistance to PAI-1 is a factor which confers clinical benefits in thrombolytic therapy. The only US FDA approved PAI-1 resistant drug is Tenecteplase$^{(R)}$. Deletion variants of t-PA have the advantage of fewer disulfide bonds in addition to higher plasma half lives. A new variant was developed by deletion of the first three domains in t-PA in addition to substitution of KHRR 128-131 amino acids with AAAA in truncated t-PA. The specific activity of this new variant, $570\;IU/{\mu}g$, was found to be similar to those found in full length t-PA (Alteplase$^{(R)}$), $580\;IU/{\mu}g$. A 65% and 85% residual activity after inhibition by rPAI-1 was observed for full length and truncated-mutant form, respectively. This new variant as the first PAI-1 resistant truncated t-PA may offer more advantages in clinical conditions in which high PAI-1 levels makes the thrombolytic system prone to re-occlusion.