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. 2016 May 24;7(11):983-987.
doi: 10.1021/acsmedchemlett.6b00062. eCollection 2016 Nov 10.

Design and Synthesis of Tesirine, a Clinical Antibody-Drug Conjugate Pyrrolobenzodiazepine Dimer Payload

Arnaud C Tiberghien  1 , Jean-Noel Levy  1 , Luke A Masterson  1 , Neki V Patel  1 , Lauren R Adams  1 , Simon Corbett  1 , David G Williams  1 , John A Hartley  1 , Philip W Howard  1
Affiliations

Design and Synthesis of Tesirine, a Clinical Antibody-Drug Conjugate Pyrrolobenzodiazepine Dimer Payload

Arnaud C Tiberghien et al. ACS Med Chem Lett. .

Abstract

Pyrrolobenzodiazepine dimers are an emerging class of warhead in the field of antibody-drug conjugates (ADCs). Tesirine (SG3249) was designed to combine potent antitumor activity with desirable physicochemical properties such as favorable hydrophobicity and improved conjugation characteristics. One of the reactive imines was capped with a cathepsin B-cleavable valine-alanine linker. A robust synthetic route was developed to allow the production of tesirine on clinical scale, employing a flexible, convergent strategy. Tesirine was evaluated in vitro both in stochastic and engineered ADC constructs and was confirmed as a potent and versatile payload. The conjugation of tesirine to anti-DLL3 rovalpituzumab has resulted in rovalpituzumab-tesirine (Rova-T), currently under evaluation for the treatment of small cell lung cancer.

Keywords: Rova-T; SG3249; Tesirine; antibody−drug conjugates; talirine.

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Conflict of interest statement

The authors declare the following competing financial interest(s): A.T., L.M., N.P., L.A., D.W., J.H., and P.H. are Spirogen employees. J.L. is a Stemcentrx employee.

Figures

Figure 1
Figure 1
Structures of SG2202 and ADC warhead SG3199. LogD values calculated at pH 7.4. Structures of payloads (drug-linker), SG3249 (tesirine), and SGD-1910 (talirine). Red coding denotes released warhead. Conventional ring numbering shown on SG3199.
Scheme 1
Scheme 1. Synthesis and Coupling of A and C Rings
Reagents and conditions: (a) HNO3, 12 °C, 95%; (b) TFA, 85 °C, 50%; (c) TIPSCl, imidazole, 100 °C, 88%; (d) NaClO2, NaH2PO4, H2O2, THF, −78 °C to rt, 100%; (e) DCC, HOBt, Et3N, DCM, −10 °C to rt, 90%; (f) TEMPO, TCCA, DCM, 100%.
Scheme 2
Scheme 2. Synthesis of Monomeric Phenol 20 and 21
Reagents and conditions: (a) Tf2O, 2,6-lutidine, DCM, −45 °C, 78%; (b) MeB(OH)2, Ag2O, AsPh3, Pd(PhCN)2Cl2, 70 °C, 70%; (c) Zn (30 equiv), HCOOH/EtOH 5/95, 30 °C, 80%; (d) Alloc-Cl, pyridine, DCM, −78 °C to rt, 100%; (e) triphosgene, Et3N, THF, 5 °C, then Alloc-Val-Ala-PAB-OH, Et3N, THF, 40 °C, 50%; (f) AcOH/MeOH/THF/water 7/1/1/2, rt, 71%, 15, 80%, 16; (g) DMSO, (COCl)2, Et3N, DCM, −78 °C to rt, 66%, 17, 60%, 18; (h) TBS-OTf, 2,6-lutidine, DCM, 0 °C, 85%, 19, 65%, 20; (i) LiOAc, DMF/water, 95/5, rt, 100%, 21, 100%, 22.
Scheme 3
Scheme 3. Final Steps, Synthesis of SG3249 (Tesirine)
Reagents and conditions: (a) 1,5-diiodopentane, K2CO3, acetone, 60 °C, 90%; (b) 22, K2CO3, acetone, 65 °C, 86%; (c) TBAF/AcOH, THF, rt, 80%; (d) Pd(PPh3)4, pyrrolidine, DCM, rt, 100%; (e) Mal-dPEG8-acid, EDCI, DCM, rt, 73%.
Figure 2
Figure 2
UPLC of SG3249: (a) unbuffered TBAF used in Scheme 3, step c; (b) buffered TBAF. Ace Excel 2 C18-AR (2 μm, 3.0 mm × 100 mm), 40 °C, 20 mM ammonium formate (pH = 4)/acetonitrile, 25/75 to 55/45 over 30 min, 0.6 mL/min. Peaks i and ii in (a) diastereoisomers of SG3249. Peak i in (b) pure SG3249.
Figure 3
Figure 3
Growth inhibition curves in human SKBR3 cells for SG3249 ADCs.
See this image and copyright information in PMC

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