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Step Pharma publishes data identifying the key role of CTP Synthase 1 in haematological malignancies

By April 4, 2023May 23rd, 2023Press Release

Press Release

St. Genis-Pouilly, France, 04 April 2023

  • Preclinical data published in HemaSphere demonstrate potential of inhibiting CTPS1 as a novel treatment approach for cancer
  • Data further support rationale for developing STP938, currently in clinical trials for the treatment of T cell and B cell lymphoma

Step Pharma, the world leader in CTPS1 inhibition for the targeted treatment of cancer, today announces the publication of compelling preclinical data detailing the therapeutic potential of inhibiting CTPS1 in haematological malignancies.

The data, published in HemaSphere (the official journal of the European Hematology Association), describe the identification and characterisation of CTP synthase 1 (CTPS1), an enzyme that catalyses a rate-limiting step in pyrimidine synthesis, as a novel therapeutic target in T cell and B cell malignancies.

Step Pharma’s selective CTPS1 inhibitors induced cell death of neoplastic lymphoid cells in vitro and demonstrated anti-tumour activity in vivo in models of both T cell and B cell malignancies.

STP938, a first-in-class, highly selective, orally bioavailable inhibitor of CTPS1 recently entered a Phase 1/2 trial for T cell and B cell lymphomas (NCT05463263) and study sites are open in the UK and the USA.

Lymphoma is the most common haematological malignancy. Despite improvements in patient survival with modern immunochemotherapy treatments, there remains a significant need for novel targeted agents to treat both T cell and B cell malignancies.

Andrew Parker, Chief Executive Officer of Step Pharma, commented:

“Our deep understanding of the pyrimidine synthesis pathway and CTPS1 biology has yielded a new targeted approach to treating blood and solid tumours. This publication summarises the important work undertaken by Step Pharma, providing compelling evidence for CTPS1 being a key therapeutic target in T and B cell malignancies. We are pleased to have developed a host of CTPS1 small molecule modulators and to be conducting Phase 1/2 clinical trials with the most advanced CTPS1 inhibitor in the world, STP938. Our ultimate goal is to drive a step change in the way we treat cancer and make a real difference in patients’ lives.”

Article citation: Asnagli et al. CTP Synthase 1 Is a Novel Therapeutic Target in Lymphoma. HemaSphere 7(4):p e864, April 2023. | DOI: 10.1097/HS9.0000000000000864


Step Pharma
Andrew Parker, Chief Executive Officer

Media Relations
Consilium Strategic Communications
Amber Fennell, Namrata Taak, Stella Lempidaki
T. +44 (0) 20 3709 5700


About STP938

STP938 is a first-in-class, highly selective, orally bioavailable inhibitor of CTP synthase 1 (CTPS1), a key component of the pyrimidine synthesis pathway. CTPS1 inhibition blocks the proliferation of neoplastic lymphoid cells and results in cell death. All cancers appear to be addicted to CTPS1 for DNA synthesis. STP938 entered clinical development in September 2022 for the treatment of T cell and B cell lymphoma.


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.

The Company’s lead asset, STP938, has received both IND and CTA clearance to proceed into first in human trials in the US and UK for the treatment of T cell and B cell lymphomas. Clinical trials in lymphoma commenced in September 2022. STP938 has the potential to be the backbone of a multitude of cancer therapies as well as a potent monotherapy for hard-to-treat blood cancers.

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 led by Kurma Partners and including 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