Helix Biopharma Corp. Announces Publication in Frontiers in Oncology on the Effects of L-DOS47 as Monotherapy in NSCLC

(TheNewswire)

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

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

The Phase I/II open-label study demonstrated thatL-DOS47 was well tolerated at doses up to 13.55 µg/kg. While nocomplete or partial responses were observed, post-hoc exploratoryanalyses in Phase I revealed that patients receiving higher dosesexperienced a statistically significant extension in progression-freesurvival (PFS), with median PFS reaching 4.1 months (approximately 16weeks) in the highest dosing quartile (P=0.0203). This finding isparticularly notable given that over 90% of these patients hadreceived two or more prior lines of therapy. Immunohistochemical tumortissue analysis of an unrelated cohort also revealed that CEACAM6 washighly expressed in nearly half of NSCLC cases, supporting theexploration of biomarker-driven patient selection for future trials.For reference, median PFS with pembrolizumab monotherapy in previouslytreated 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-DOS47and highlights the importance of CEACAM6 as a new biomarker forbiologics for the treatment of lung cancer,” said Brenda Lee, corresponding author andClinical Director at Helix . “It lays thegroundwork for further development of L-DOS47 as part of combinationstrategies in CEACAM6-expressing cancers.”

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

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

About Helix BioPharma Corp.

Helix BioPharma is an oncology company that innovatesfrom strength to bring near-term solutions for today’shardest-to-treat cancers. The Company’s pipeline is led by TumorDefense Breaker™ L-DOS47, a clinical-stageantibody-enzyme conjugate designed to prime CEACAM6-expressing tumorsfor increased sensitivity to therapy and augment the effectiveness oftoday’s front-running anti-cancer treatments. L-DOS47 has completedPhase Ib studies in non-small cell lung cancer (NSCLC) and shares itsCEACAM6-targeting foundation with Helix’s next-generationbi-specific antibody-drug conjugates (ADCs), currently in discovery.The Company also advances two pre-IND candidates: (i) LEUMUNA™, anoral immune checkpoint modulator aimed at achieving durable remissionin post-transplant leukemia relapse, and (ii) GEMCEDA™, afirst-in-class oral gemcitabine prodrug with bioavailability on a parwith 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/

—ENDS—

For more information, pleasecontact:

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

corporate@helixbiopharma.com

Forward-Looking Statements and Risksand Uncertainties

This news release containsforward-looking statements and information (collectively,“forward-looking statements”) within the meaning of applicableCanadian securities laws. Forward-looking statements are statementsand information that are not historical facts but instead includefinancial projections and estimates, statements regarding plans,goals, objectives, intentions and expectations with respect to theCompany’s future business, operations, research and development,including the Company’s activities relating to Tumor DefenseBreaker™ L-DOS47, LEUMUNA™ and GEMCEDA™. These statements useterms like “estimates,” “expects,” “will,” and similarlanguage indicating future events, or the negative thereof or anyother comparable terminology referring to future events orresults.

However, forward-looking statementsare subject to risks and uncertainties beyond Helix’s control,which may lead to actual results differing materially from thoseanticipated. These risks and uncertainties include, but are notlimited to, risks relating to Helix’s financial condition, including(a) lack of significant revenues to date and reliance on equity andother financing; (b) business, including its stage of development,government regulation, development success of and market acceptancefor its products, rapid technological change and dependence on keypersonnel; (c) intellectual property including the ability of Helix toprotect its intellectual property and dependence on its strategicpartners; and (d) capital structure, including its lack of dividendson its common shares, volatility of the market price of its commonshares and public company costs. Forward-looking statements reflectthe management’s current beliefs and are based on informationavailable to the management on the date of this news release, and theCompany does not assume the obligation to update any forward-lookingstatement should those beliefs change, except as required bylaw. Further information regarding these risks and uncertainties canbe found in Helix’s periodic reports and information forms on theCompany’s SEDAR+ profile at www.sedarplus.ca .

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

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