8-K: Silexion's SIL204 Shows Pan-KRAS Activity, 99.7% Inhibition

Silexion Therapeutics announced positive new human cell line data for SIL204, confirming pan-KRAS activity with up to 99.7% inhibition and first evidence in gastric cancer.

Summary

• SIL204 demonstrated activity against eleven human cell lines originating from 5 different organ cancer sites, each with a specific KRAS mutation.
• High inhibition rates ranged from 83.5% to 99.7% at nanomolar concentrations, with IC50 values between 23.4 nM and 85.3 nM.
• The company reported first evidence of gastric cancer activity, with the SNU-601 cell line (G12D mutation) showing 89.2% inhibition.
• Expanded validation in colorectal cancer was achieved, with the HCT 116 cell line (G13D mutation) demonstrating an IC50 of 105 nM.
• Highest activity to date was observed in NCIH2009 lung cancer cells (G12A mutation), showing 99.7% inhibition.
• Pancreatic cancer G12R confirmation was achieved in the KP2 cell line, showing 91.5% inhibition with an IC50 of 31.5 nM, addressing a mutation affecting 17% of pancreatic cancer patients.
• Comprehensive lung cancer activity was demonstrated across four cell lines, with 83.5% to 99.7% inhibition for G12C, G13C, G12A, and G12V mutations.
• SIL204 now demonstrates activity against G12D, G12V, G12R, G12C, G13C, G12A, Q61H, and G13D mutations, covering virtually all KRAS-driven cancers.
• KRAS mutations are prevalent in approximately 90% of pancreatic cancers, 45% of colorectal cancers, and 35% of non-small cell lung cancers.

Sentiment

Score: 9

Explanation: The filing presents highly positive preclinical data for SIL204, demonstrating exceptional potency, broad pan-KRAS mutation coverage, and expansion into new cancer types. This significantly de-risks the early development stage and positions the drug candidate favorably for future clinical trials, indicating strong potential for addressing a major unmet medical need.

Positives

• SIL204 demonstrated exceptional potency across all tested human cancer cell lines, achieving 83.5% to 99.7% maximum inhibition.
• The drug candidate showed activity against a broad range of clinically significant pan-KRAS mutations, including G12D, G12V, G12R, G12C, G13C, G12A, Q61H, and G13D.
• First evidence of activity in gastric cancer expands SIL204's potential therapeutic reach to a fifth cancer type.
• The highest activity reported for SIL204 to date was 99.7% inhibition in NCIH2009 lung cancer cells (G12A mutation).
• Confirmation of activity against the G12R mutation in pancreatic cancer is significant, as this mutation affects 17% of pancreatic cancer patients and has been difficult to inhibit by small molecule KRAS inhibitors.
• The data validates SIL204 as a comprehensive pan-KRAS isoform selective inhibitor, specific for KRAS but not other RAS isozymes.

Risks

• Ability to successfully complete preclinical studies and initiate clinical trials.
• Silexion's strategy, future operations, financial position, projected costs, prospects, and plans.
• Impact of the regulatory environment and compliance complexities.
• Expectations regarding future partnerships or other relationships with third parties.
• Future capital requirements and sources and uses of cash, including the ability to obtain additional capital.
• Ability to maintain Nasdaq listing.
• Other risks and uncertainties set forth in documents filed with the SEC, including the Annual Report on Form 10-K for the year ended December 31, 2024.

Future Outlook

Silexion Therapeutics plans to advance SIL204 toward Phase 2/3 clinical trials in the first half of 2026. Regulatory submissions to the Israel Ministry of Health are expected in Q4 2025, followed by submissions to the European Union in Q1 2026. The broad mutation coverage and multi-cancer activity demonstrated in these studies support a comprehensive clinical development strategy for SIL204.

Management Comments

• Ilan Hadar, Chairman and CEO, stated that the results validate SIL204 as a true pan-KRAS therapeutic candidate, demonstrating high activity against a range of different KRAS mutations across multiple cancer types.
• Hadar highlighted that the ability to achieve near-complete inhibition across such a diverse range of mutations positions SIL204 uniquely in the competitive landscape.
• Hadar emphasized that SIL204's coverage, extending from common G12D and G12V mutations to rarer variants like G12R, G13D, and G13C, supports building a comprehensive solution for KRAS-driven cancers that could address a significantly broader patient population than existing targeted therapies.

Industry Context

The announcement positions SIL204 as a potentially significant advancement in the oncology field, particularly for KRAS-driven cancers, which are notoriously difficult to treat and represent a large patient population across various solid tumors. The pan-KRAS activity and high inhibition rates suggest a broader therapeutic applicability compared to existing targeted therapies that often focus on specific KRAS mutations. This broad coverage could address a substantial unmet medical need, as KRAS mutations are prevalent in major cancers like pancreatic, colorectal, and non-small cell lung cancers.

Comparison to Industry Standards

• SIL204's activity against the G12R mutation in pancreatic cancer is notable, as this specific mutation has been difficult to inhibit by small molecule KRAS inhibitors currently in development or on the market.
• The ability to achieve near-complete inhibition (up to 99.7%) across a diverse range of KRAS mutations positions SIL204 uniquely in a competitive landscape often characterized by therapies targeting single or limited KRAS variants.

Stakeholder Impact

• Shareholders: Positive impact due to strong preclinical data for a lead drug candidate, potentially increasing company valuation and future prospects.
• Patients: Potential for a comprehensive therapeutic solution for a broad range of KRAS-driven cancers, including those with mutations difficult to treat with existing therapies.
• Employees: Positive impact from advancing the company's pipeline and achieving significant scientific milestones.

Next Steps

• Advance SIL204 toward Phase 2/3 clinical trials.
• Submit regulatory applications to the Israel Ministry of Health in Q4 2025.
• Submit regulatory applications to the European Union in Q1 2026.

Key Dates

Recommendation

The strong preclinical data for SIL204, demonstrating exceptional potency and broad pan-KRAS activity across multiple difficult-to-treat cancer types, represents a significant de-risking event for Silexion Therapeutics. The drug's ability to inhibit mutations like G12R, which are challenging for existing therapies, positions it uniquely. With clear next steps towards Phase 2/3 clinical trials and regulatory submissions, this announcement suggests substantial future value creation potential, making it a strong buy for investors seeking exposure to innovative oncology treatments.

Keywords

Silexion Therapeutics, SIL204, KRAS, RNAi therapy, cancer treatment, oncology, pancreatic cancer, colorectal cancer, lung cancer, gastric cancer, preclinical data, mutation inhibition, G12D, G12V, G12R, G12C, G13C, G12A, Q61H, G13D