Step Pharma to spotlight work in CTPS2-null solid tumours at 2025 EORTC-NCI-AACR International Conference on Molecular Targets and Cancer Therapeutics

Saint-Genis-Pouilly, France, 21 October 2025 – Step Pharma (“the Company”), the global leader in CTPS1 inhibition for targeted cancer treatment, today announces that its Chief Scientific Officer, Philip Beer, will be presenting data on the identification of a CTPS1-dependent synthetic lethality in solid tumours at the 2025 EORTC-NCI-AACR International Conference on Molecular Targets and Cancer Therapeutics, being held from 22-26 October in Boston, MA.

The presentation will focus on the use of the AACR Project GENIE data, a publicly accessible cancer registry of real-world clinico-genomic data, to identify loss of CTPS2 as a novel biomarker to select solid tumours with a synthetic lethal dependency on CTPS1. Deletion of CTPS2 was subsequently identified as a frequent event in many cancer types, with the highest prevalence found in ovarian cancer. As tumours derived from epithelial tissues can utilise both CTPS1 and CTPS2 in the final step of the CTP synthesis cascade, loss of CTPS2 in solid tumours exposes a dependence which could be targeted with CTPS1 inhibition to prevent tumour cell proliferation.

As a result of these findings, dencatistat, an orally available and highly potent inhibitor of CTPS1, which is currently being evaluated in a phase 1a dose escalation study in patients with solid tumours, will be evaluated in safety expansion cohorts in patients with CTPS2 null cancers, with the first being ovarian cancer (NCT06297525). Selecting patients whose tumours have deleted CTPS2 represents a precision oncology approach that is expected to maximise the therapeutic potential of dencatistat.

Philip Beer, Chief Scientific Officer of Step Pharma, said: “Our work analysing clinico-genomic data led us to identify patients with CTPS2 null solid tumours as a promising therapeutic application for dencatistat. About 15-20% of ovarian cancers harbour this deletion, and so through inhibition of CTPS1 with dencatistat, we can selectively target the de novo pyrimidine synthesis pathway in ovarian cancer and other solid tumours. I look forward to presenting at the EORTC-NCI-AACR international conference and to initiating the first expansion cohort in the near future.”

Session: AACR Project GENIE: Powering Drug Discovery Through an International Consortium’
Presentation title: Using GENIE data to drive oncology target identification and drug development.
Date: Thursday 23 October 2025
Time: 17:55 EDT

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About Step Pharma
Step Pharma’s goal is to bring about a step change in how cancer is treated with targeted therapies that kill cancer cells and leave healthy cells unharmed. The Company is the world leader in CTPS1 inhibition, a new approach with the potential to yield highly selective, safe and effective treatments for both blood cancers and solid tumours.

Step Pharma was founded in 2014 by Kurma Partners, the Imagine Institute and Sygnature Discovery, based on the scientific discoveries of Prof. Alain Fischer and Dr Sylvain Latour. Step Pharma is based in Saint-Genis-Pouilly, France, and is supported by a strong syndicate of investors including Kurma Partners, V-Bio Ventures, Bpifrance (Fonds Biothérapies Innovantes et Maladies Rares and InnoBio2 Fund), Pontifax, Hadean Ventures, Sunstone Life Science Ventures, Inserm Transfert Initiative, Idinvest, Sygnature Discovery and the Imagine Institute. More information on the company can be found at www.step-ph.com.

For more information please contact:

Step Pharma
Andrew Parker, Chief Executive Officer
contact@step-ph.com

Media Relations
ICR Healthcare
Amber Fennell, Namrata Taak, Phillip Marriage
Tel. +44 (0) 20 3709 5700
steppharma@icrhealthcare.com