invoX Pharma Presents Positive Clinical Data from Phase 1 Study of FS222 in Patients with Advanced Solid Tumours at the 2024 American Society of Clinical Oncology Annual Meeting

LONDON, United Kingdom – June 3, 2024 – Today, invoX Pharma Limited (“invoX”), a research-driven global biopharmaceutical company with an advancing pipeline of innovative products, has presented updated findings from its ongoing phase 1 study of FS222, an investigational CD137/PD-L1 bispecific antibody, in patients with advanced solid tumours. These data demonstrated encouraging anti-tumour activity in multiple tumour types with a manageable safety profile. These preliminary findings were presented today at the 2024 American Society of Clinical Oncology Annual Meeting in Chicago as an oral presentation during the Development Therapeutics – Immunology Session.

FS222 is a novel tetravalent bispecific antibody, using invoX's proprietary Fcab® platform technology, that drives PD-L1 dependent CD137 agonism. The data presented today are from 100 subjects in the ongoing first-in-human (FIH) dose-escalation phase 1 clinical trial of FS222 (NCT04740424) in patients with advanced solid tumours. The study is designed to evaluate safety and identify the maximum tolerated dose, with secondary objectives related to anti-tumour activity, pharmacokinetics, and pharmacodynamics.

As a monotherapy dosed once every 4 weeks, FS222 increased T cell proliferation and intratumoural CD8+ T cell infiltration across a wide range of doses. The rate of treatment-related adverse events (TRAEs) was generally dose dependent.  Overall, TRAEs were consistent with the intended dual mechanism of action of CD137 agonism and PD-L1-blockade and were generally manageable and reversible. Grade ≥ 3 TRAEs occurred in 36/100 subjects, with the most common including increases in aspartate aminotransferase and alanine aminotransferase, thrombocytopenia, neutropenia and febrile neutropenia.

In the study, FS222 demonstrated encouraging anti-tumour activity in multiple tumour types. Responses (as defined by RECIST1.1 criteria) were observed in cutaneous melanoma (n=9), ovarian cancer (n=2), non-small cell lung cancer (NSCLC) (n=2), and one each for mucosal melanoma, triple negative breast cancer (TNBC), mesothelioma and MSS colorectal cancer. The rate of disease control (defined as the rate of complete responses, partial responses and stable disease combined) was 45.0% for all patients in the study.

In 19 patients with metastatic/advanced cutaneous melanoma previously treated with a PD-1 antibody the overall response rate (defined as the rate of complete responses and partial responses combined) was 47.4% and the disease control rate was 68.4%.

Elena Garralda, MD, MSc, Director of Early Drug Development at Vall d’Hebron University Hospital, said: “While there have been great advances in immuno-oncology research, existing treatments continue to face challenges with response rates and duration of response, especially in treatment-resistant cancer. The opportunity to target multiple complementary immune mechanisms with a single agent is very exciting and has significant potential to address an unmet need for patients. These results for FS222 are really encouraging and should be studied further, as they show a promising anti-tumour effect with a manageable safety profile.” 

Ben Toogood, Chief Executive Officer at invoX, said: “We are encouraged by these results and are impressed by the preliminary anti-tumour activity observed with FS222, especially in melanoma patients previously treated with a PD-1 antibody. There is an urgent need for innovative immuno-oncology treatments for patients with treatment-resistant cancers. We see significant potential for FS222 in this area and will continue to investigate FS222 further, with the aim of providing benefit to patients in the future.”

Ben added: “These data also provide important validation of our antibody platform. We are excited about the potential to utilise our proprietary CD137-agonist domain from our Fcab® platform in additional bispecific antibodies targeting multiple tumour types and patient populations.”

Enrollment in this phase 1 study of FS222 is ongoing and the study is exploring additional FS222 dose optimization.