Exscientia acquires $20m CDK7 inhibitor, plans breast cancer trial

Exscientia has recently taken complete ownership of an oral cyclin-dependent kinase 7 (CDK7) inhibitor, acquiring the shares held by its development partner, GT Apeiron Therapeutics. This acquisition entailed an upfront payment of $20 million, divided equally between cash and equity. Following this transaction, Exscientia will be responsible for all current development expenses associated with the drug, while also compensating GT Apeiron with sales royalties.

The CDK7 candidate, designated as GTAEXS617, is the focus of ongoing investigation in a Phase I/II dose-escalation trial known as ELUCIDATE (NCT05985655). This trial aims to explore the drug's efficacy both as a standalone treatment and in combination with standard therapies among patients suffering from advanced or metastatic solid tumors. Exscientia anticipates a data readout from this trial in the second half of the year.

Pending positive results from the current trial, Exscientia intends to further examine the potential of GTAEXS617 as a combination therapy specifically for patients with recurrent or advanced hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative breast cancer.

The company strongly supports the CDK7 candidate, asserting that GTAEXS617 could potentially address significant safety and efficacy issues present in existing approved treatments. Furthermore, Exscientia believes the therapy might effectively overcome common resistance pathways linked to CDK4/6 inhibitors, including Pfizer’s Ibrance (palbociclib) and Novartis and Astex’s Kisqali (ribociclib).

Currently, no CDK7 inhibitors have received regulatory approval, with most candidates still in the early stages of development. One notable company also engaged in developing CDK7 inhibitor treatments is Carrick Therapeutics. Carrick is actively researching a CDK7 inhibitor named samuraciclib (CT7001) as a combination therapy for breast cancer. They are conducting a Phase II trial (NCT05963997) to evaluate samuraciclib in conjunction with Menarini Group’s oral selective estrogen receptor degrader, Orserdu (elacestrant), for HR+/HER2- metastatic breast cancer patients.

Additionally, Carrick is investigating the use of samuraciclib in combination with Arvinas and Pfizer’s vepdegestrant, an investigational oral PROteolysis Targeting Chimera (PROTAC) estrogen receptor protein degrader. This combination is being assessed in a Phase I/II trial (NCT06125522) for patients with estrogen receptor-positive (ER+)/HER2- advanced or metastatic breast cancer.

In summary, Exscientia's acquisition of full ownership over the CDK7 candidate GTAEXS617 marks a significant step forward in its development. The ongoing and future trials aim to address both standalone and combination treatment potentials, specifically targeting advanced and resistant forms of cancer. The broader landscape of CDK7 inhibitors remains largely experimental, with key players like Carrick Therapeutics pushing similar boundaries in breast cancer treatment.