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Sareum Holdings PLC

(“Sareum” or the “Company”)

Sareum notes key takeaways from Sierra Oncology webcast to discuss positive preliminary results from Phase 1/2 trials with SRA737 presented at ASCO

Sareum Holdings plc (AIM: SAR), the specialist small molecule drug development business, notes that Sierra Oncology (the licence holder for SRA737) held an analyst and investor event today featuring distinguished oncologists Professor Johann de Bono and Dr Rebecca Kristeleit, to discuss clinical findings and possible next steps for SRA737, its oral, highly selective Chk1 inhibitor. Positive preliminary clinical data from two first-in-human Phase 1/2 studies of SRA737, as monotherapy and as SRA737+LDG (low dose gemcitabine), were presented on Saturday 1 June at the 2019 Annual Meeting of the American Society of Clinical Oncology (ASCO) in Chicago. Detailed results were issued by press release on 1 June and both press release and the posters are available at www.sierraoncology.com.

The webcast presentation can be downloaded here.

Key highlights of the webcast were:

• SRA737 is competitively positioned as potentially one of the leading clinical assets targeting the DNA damage repair (DDR) pathway with clinical safety & efficacy of SRA737 +/-LDG supporting standalone development and in combination with both PARP inhibitors (PARPi) and immuno-oncology (IO) therapy such as immune checkpoint blockade
• The two Phase 1/2 signal-seeking clinical trials were successful in establishing safety and proof-of-concept activity in multiple cancer indications, i.e. identifying genetic contexts that sensitise tumours to SRA737; that LDG potentiates SRA737 activity; and that anti-cancer activity correlated with genetic contexts
• A very promising signal was observed in anogenital cancer, which represents a tractable opportunity to potentially pursue trials leading to market registration filings given its unmet medical need, particularly in patients for whom initial 1^st-line therapy has become ineffective, and substantial potential market opportunity
• There is a clear rationale for combining a targeted DDR agent with PARPi & IO therapy, both of which provide compelling additional opportunities, with illustrative clinical trial designs given that:
  • Acquired PARPi resistance is a significant and growing clinical problem that Chk1 inhibition could address, with promising data already observed in preclinical studies in this setting – a Phase 1b/2 trial of SRA737+PARPi (niraparib) is expected to begin with the timing of its initiation still to be decided
  • Sierra has presented evidence for synergistic interplay between the DDR network and tumour immune response, with SRA737+LDG activating innate immunity resulting in a highly favourable immune anti-tumour microenvironment and profound tumor regressions in preclinical models – Sierra has noted that it has received management support from a major IO company to  potentially supply its leading immunotherapeutic agent to run a combination study with SRA737
• Sierra stated that its next steps are
  • To evaluate further the clinical data in the context of its emerging pipeline, noting that a Phase 2 registration trial for SRA737+LDG in anogenital cancer would cost an estimated $10 million
  • Explore options to enable continued advancement of SRA737

Dr Tim Mitchell, CEO of Sareum Holdings, said: “The enthusiasm for the clinical data and the potential of SRA737 was evident among the attendees in Chicago at Sierra’s webcast today. It seems clear that, with proof-of-concept established, there are multiple opportunities for the ongoing development of this exciting prospect, particularly in combination with other therapeutic approaches. The success of the trials and the exciting future development opportunities discussed increases the likelihood of further milestone payments being received and we look forward to further development updates in due course.”

SRA737 was discovered and initially developed by scientists at The Institute of Cancer Research, London, UK in collaboration with Sareum, and with funding from Cancer Research UK. SRA737 was licensed to Sierra Oncology for up to $328.5 million plus royalties by co-investment partner, CRT Pioneer Fund. Sareum is eligible to receive up to $88 million in milestone payments, plus sales royalties as SRA737 advances.

Professor Johann de Bono is Regius Professor of Cancer Research, Head of the Division of Clinical Studies and Professor in Experimental Cancer Medicine at The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust;

Dr Rebecca Kristeleit is Clinical Senior Lecturer and Honorary Consultant Medical Oncologist at University College London (UCL) Cancer Institute & UCLH Dept. of Oncology, a leading expert in gynaecological malignancies.

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Notes for editors: 

Sareum is a specialist drug development company delivering targeted small molecule therapeutics, to improve the treatment of cancer and autoimmune disease. The Company generates value through licensing its candidates to international pharmaceutical and biotechnology companies at the preclinical or early clinical trials stage.

Sareum’s leading clinical-stage programme, SRA737, a novel Checkpoint kinase 1 (Chk1) inhibitor licensed to NASDAQ-listed Sierra Oncology, is in Phase 2 clinical trials targeting ovarian and other advanced cancers. The key role of Chk1 in cancer cell replication and DNA damage repair suggests that SRA737 may have broad application as a targeted therapy in combination with other oncology and immune-oncology drugs in genetically defined patients.

Sareum is also advancing internal programmes focused on distinct dual tyrosine kinase 2 (TYK2) /Janus kinase 1 (JAK1) inhibitors through preclinical development as therapies for autoimmune diseases (SDC-1801) and cancers (SDC-1802). TYK2 and JAK1 have roles in pro-inflammatory responses in autoimmune diseases (e.g. psoriasis, rheumatoid arthritis, inflammatory bowel diseases and lupus) and tumour cell proliferation in certain cancers (e.g. T-cell acute lymphoblastic leukaemia and some solid tumours). The Company is targeting first human clinical trials in each indication in 2020.

The Company also has an Aurora+FLT3 inhibitor targeting haematological cancers, which is at the preclinical development stage.

Sareum Holdings plc is listed on the AIM market of the London Stock Exchange, trading under the ticker SAR. For further information, please visit www.sareum.co.uk

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