Methotrexate α-tert-butyl ester, capped by OtBu, significantly reduces tumor growth in HT1080 tumor bearing mice. Methotrexate is an antimetabolite and antifolate agent and is also an immunosuppressant and antineoplastic agent. In Vitro OtBu-MTX-PVG is less HT1080 than MTX-PVG against HT1080 cells. It shows that protection of the α-carboxyl group of MTX results in reduced in vitro activity. MCE has not independently confirmed the accuracy of these methods. They are for reference only. In Vivo Lys-MTXcleavable- (OtBu) significantly reduces tumor growth in HT1080 tumor bearing mice . The protection of the α-carboxyl group of methotrexate may be used to improve the circulatory half-life and reduce the liver accumulation of similar MTX-conjugated dendrimers, while still retaining antitumor activity in vivo . MCE has not independently confirmed the accuracy of these methods. They are for reference only. Animal Model: Female, Balb/c nu/nu, 6 weeks (bearing HT1080 cells) Dosage: 30 mg/kg Administration: Once per week for 2 weeks Result: Showed a significant (63%) reduction in tumor size on day 12. Form:Solid