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Exatecan mesylate is a semisynthetic, water-soluble derivative of camptothecin with antineoplastic activity. Exatecan mesylate inhibits topoisomerase I activity by stabilizing the cleavable complex between topoisomerase I and DNA and inhibiting the religation of DNA breaks, thereby inhibiting DNA replication and triggering apoptotic cell death. This agent does not require enzymatic activation and exhibits greater potency than camptothecin and other camptothecin analogs. 

Exatecan Mesylate (DX8951f) is a topoisomerase I inhibitor with an IC50 value of 2.2 μM (0.975 μg/mL) for cancer research.

Exatecan mesylate inhibits topoisomerase I activity by stabilizing the cleavable complex between topoisomerase I and DNA and inhibiting religation of DNA breaks, thereby inhibiting DNA replication and triggering apoptotic cell death. This agent does not require enzymatic activation and exhibits greater potency than camptothecin and other camptothecin analogues^[3].

The synthesis of Exatecan mesilate is as follows:
500mL reaction flask,To a suspension of compound II (15 g, 1.0 eq) in ethylene glycol monomethyl ether (150 mL),After adding methanesulfonic acid (75 mL) and water (75 mL) under cooling,The solution was heated under reflux for 24 hours,The reaction was complete as detected by LCMS and cooled to 25°C.Remove the solvent under reduced pressure, add 2L methanol, stir for 2 hours and filter,The filter cake was washed with 200 mL methanol,Dry to obtain 9g of yellow ixitecan mesylate crude product,Yield 53.9%, HPLC purity: 96%.

Exatecan mesylate is a synthetic camptothecin analog that is a more potent inhibitor of topoisomerase I than camptothecin, topotecan, and the active metabolite of irinotecan (CPT-11), SN-38. In preclinical studies, exatecan mesylate demonstrated broad antitumor activity compared with available camptothecin analogs. Furthermore, the antitumor activity observed in Phase I trials made exatecan mesylate an attractive compound for clinical development. A Phase II trial was designed to further evaluate the activity and pharmacokinetic (PK) profile of exatecan mesylate and determine its toxicity and tolerability in patients with metastatic breast carcinoma treated previously with anthracyclines and taxanes[1-2].

[1] M.D., Francisco J. Esteva and Ph.D. “A Phase II study of intravenous exatecan mesylate (DX-8951f) administered daily for 5 days every 3 weeks to patients with metastatic breast carcinoma.” Cancer 98 5 (2003): 900–907.
[2] D. Talbot. “Phase II study of Exatecan Mesylate (DX-8951f) in advanced NSCLC.” Lung Cancer 29 1 (2000): 55.