Toronto, Ontario – TheNewswire - 13 August 2025 – Helix BioPharma Corp. (TSX: “HBP”, OTC PINK: “HBPCD”, FRANKFURT: “HBP0”) (“Helix” or the “Company”), a clinical-stage oncology company shaping a near future where today’s hard-to-treat cancers are vincible, announced today the publication of a peer-reviewed article in Frontiers in Oncology titled “Safety of unconventional antibody-drug conjugate L-DOS47 in a Phase I/II monotherapy study targeting advanced NSCLC”.

The publication reports results from a previously completed Phase I/II clinical study of L-DOS47 as a single agent in patients with advanced non-small cell lung cancer (NSCLC). Initiated in 2012 with clinical sites in Poland and later, academic institutions in Canada, the study evaluated the safety, tolerability, and preliminary efficacy in NSCLC of monotherapy with L-DOS47, Helix’s lead candidate. L-DOS47 is first-in-class antibody-enzyme conjugate (AEC) designed to selectively target CEACAM6-expressing solid tumors and locally neutralize the pH of the acidic tumor microenvironment (TME), which is increasingly recognized as a critical barrier to efficacious therapy.

The Phase I/II open-label study demonstrated that L-DOS47 was well tolerated at doses up to 13.55 µg/kg. While no complete or partial responses were observed, post-hoc exploratory analyses in Phase I revealed that patients receiving higher doses experienced a statistically significant extension in progression-free survival (PFS), with median PFS reaching 4.1 months (approximately 16 weeks) in the highest dosing quartile (P=0.0203). This finding is particularly notable given that over 90% of these patients had received two or more prior lines of therapy. Immunohistochemical tumor tissue analysis of an unrelated cohort also revealed that CEACAM6 was highly expressed in nearly half of NSCLC cases, supporting the exploration of biomarker-driven patient selection for future trials. For reference, median PFS with pembrolizumab monotherapy in previously treated NSCLC populations typically ranges from 2 to 6.3 months, depending on PD-L1 expression levels.¹

“This study supports the safety profile of L-DOS47 and highlights the importance of CEACAM6 as a new biomarker for biologics for the treatment of lung cancer,” said Brenda Lee, corresponding author and Clinical Director at Helix. “It lays the groundwork for further development of L-DOS47 as part of combination strategies in CEACAM6-expressing cancers.”

“We’re excited to build on these findings by advancing L-DOS47 into a new clinical study in combination with the PD-1 inhibitor pembrolizumab,” said Thomas Mehrling, MD, PhD, CEO of Helix BioPharma. “By neutralizing tumor acidity, L-DOS47 has the potential to create a more favorable tumor microenvironment for immunotherapies like checkpoint inhibitors to work more effectively. We have just received positive feedback from the FDA on our planned Phase I/II study in combination with pembrolizumab, and we are now laser-focused on executing this next crucial step in the development of L-DOS47 in NSCLC.”

The full article is available online in Frontiers in Oncology: https://www.frontiersin.org/journals/oncology/articles/10.3389/fonc.2025.1544967/full

About Helix BioPharma Corp.

Helix BioPharma is an oncology company that innovates from strength to bring near-term solutions for today’s hardest-to-treat cancers. The Company’s pipeline is led by Tumor Defense Breaker™ L-DOS47, a clinical-stage antibody-enzyme conjugate designed to prime CEACAM6-expressing tumors for increased sensitivity to therapy and augment the effectiveness of today’s front-running anti-cancer treatments. L-DOS47 has completed Phase Ib studies in non-small cell lung cancer (NSCLC) and shares its CEACAM6-targeting foundation with Helix’s next-generation bi-specific antibody-drug conjugates (ADCs), currently in discovery. The Company also advances two pre-IND candidates: (i) LEUMUNA™, an oral immune checkpoint modulator aimed at achieving durable remission in post-transplant leukemia relapse, and (ii) GEMCEDA™, a first-in-class oral gemcitabine prodrug with bioavailability on a par with IV, designed to expand treatment options for advanced cancers.

Helix is listed on TSX (HBP), OTC PINK (HBPCD), and FWB (HBP0). For more information, please visit: https://www.helixbiopharma.com/

For more information, please contact:

Helix BioPharma Corp.

Bay Adelaide Centre - North Tower

40 Temperance Street, Suite 2

Toronto, ON M5H 0B4

Tel: +1 857 208 7687

Thomas Mehrling, CEO

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Forward-Looking Statements and Risks and Uncertainties

This news release contains forward-looking statements and information (collectively, “forward-looking statements”) within the meaning of applicable Canadian securities laws. Forward-looking statements are statements and information that are not historical facts but instead include financial projections and estimates, statements regarding plans, goals, objectives, intentions and expectations with respect to the Company’s future business, operations, research and development, including the Company’s activities relating to Tumor Defense Breaker™ L-DOS47, LEUMUNA™ and GEMCEDA™. These statements use terms like “estimates,” “expects,” “will,” and similar language indicating future events, or the negative thereof or any other comparable terminology referring to future events or results. 

However, forward-looking statements are subject to risks and uncertainties beyond Helix’s control, which may lead to actual results differing materially from those anticipated. These risks and uncertainties include, but are not limited to, risks relating to Helix’s financial condition, including (a) lack of significant revenues to date and reliance on equity and other financing; (b) business, including its stage of development, government regulation, development success of and market acceptance for its products, rapid technological change and dependence on key personnel; (c) intellectual property including the ability of Helix to protect its intellectual property and dependence on its strategic partners; and (d) capital structure, including its lack of dividends on its common shares, volatility of the market price of its common shares and public company costs. Forward-looking statements reflect the management’s current beliefs and are based on information available to the management on the date of this news release, and the Company does not assume the obligation to update any forward-looking statement should those beliefs change, except as required by law. Further information regarding these risks and uncertainties can be found in Helix’s periodic reports and information forms on the Company’s SEDAR+ profile at www.sedarplus.ca.

¹ https://linkinghub.elsevier.com/retrieve/pii/S0140673615012817 ; https://www.nejm.org/doi/10.1056/NEJMoa1501824