Scale-up Synthesis of Tesirine

Abstract

This work describes the enabling synthesis of tesirine, a pyrrolobenzodiazepine antibody−drug conjugate druglinker. Over the course of four synthetic campaigns, the discovery route was developed and scaled up to provide a robust manufacturing process. Early intermediates were produced on a kilogram scale and at high purity, without chromatography. Midstage reactions were optimized to minimize impurity formation. Late stage material was produced and purified using a small number of key high-pressure chromatography steps, ultimately resulting in a 169 g batch after 34 steps. At the time of writing, tesirine is the drug-linker component of eight antibody−drug conjugates in multiple clinical trials, four of them pivotal.

Early Development, Scale-Up, and Reverse-Phase Purification of a Highly Potent Pyrrolobenzodiazepine Dimer, SG3259, for Use in Antibody–Drug Conjugates

“…Pyrrolobenzodiazepine (PBD) dimers are fully synthetic highly potent small molecules currently being developed as warheads for antibody–drug conjugates (ADCs). − PBD analogues have demonstrated extremely high potencies (low picomolar) by acting as DNA minor-groove binding cross-linkers in both dividing and nondividing cells. , SG3259 ( 1 ) is a PBD dimer linker drug in development by AbbVie (formerly Stemcentrx) for use in its ADC platform. − Several closely related PBD–ADCs have been and continue to be evaluated in clinical trials including the discontinued SGN-CD33A and Rova-T (PBDs talirine and tesirine ( 2 ), respectively), and the ongoing ADCT-301 and ADCT-402 (both tesirine linker drugs). , Considerable attention has been given to the gram-scale synthesis of tesirine ( 2 ), − but there are no publications on the development of terminally linked PBD linker drugs such as SG3259 ( 1 ). SG3259 has several notable structural differences from the more commonly employed tesirine (SG3249, 2 ), including a modified linker attachment site, added piperazine and aniline moieties, and an alkyl spacer (Figure ).…”

An Alternative Focus for Route Design for the Synthesis of Antibody–Drug Conjugate Payloads

“…The leading PBD linker-payload is tesirine ( 1 , SG3249), which is utilized in rovalpituzumab tesirine (Rova-T) for the treatment of small cell lung cancer and loncastuximab tesirine (Lonca-T) for the treatment of B-cell non-Hodgkin lymphoma, as well as in a range of further programs. The initial synthesis of tesirine has been described previously, as well as a detailed description of the synthetic development and scale-up of this route …”

An Isomerization Approach to Tesirine and Pyrrolobenzodiazepines

“… For our Discovery program the Suzuki reaction with the enol triflate is an effective approach allowing access to a range of differential functionalized PBDs. However, the route is inefficient for the manufacture of tesirine, as only one carbon atom is introduced, and the reaction has proved challenging to scale-up …”

“…8 The original synthesis of tesirine has been reported, 9 followed by details of the development and scale-up of this route. 10 More recently we reported that a Cost of Goods analysis of the original route revealed that the majority of the manufacturing cost was attributable to the final high containment 11 steps of the synthesis. A revised synthesis was developed, minimizing the number of high containment steps which made a significant reduction to the Cost of Goods.…”

“…However, the route is inefficient for the manufacture of tesirine, as only one carbon atom is introduced, and the reaction has proved challenging to scale-up. 10 As part of the array of PBDs synthesized, a range of molecules with an exo-methylene double bonds have been evaluated as both standalone therapeutics and ADC payloads. SG2000 (9) has completed Phase II clinical trials in patients with leukemia and ovarian cancer, 13 and both this molecule and SG2057 (10) 14 are under evaluation as ADC payloads by AstraZeneca (linker-payloads SG3400 15 and SG3600 16 ) and Genentech (linker-payloads SG3231 and SG3451 17 ).…”