On August 6, 2025 Moleculin Biotech, Inc., (Nasdaq: MBRX) ("Moleculin" or the "Company"), a late-stage pharmaceutical company with a broad portfolio of drug candidates targeting hard-to-treat tumors and viruses, reported the presentation of encouraging preclinical data for its lead drug candidate, Annamycin, also known by its non-proprietary name of naxtarubicin, which demonstrated significant efficacy against various primary and metastatic liver cancers, including hepatocellular carcinoma (HCC), colorectal liver metastases, and pancreatic ductal adenocarcinoma (PDAC) liver metastases (Press release, Moleculin, AUG 6, 2025, View Source [SID1234654867]). This is believed to be the result of targeted accumulation in the liver and other organs.

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These findings were highlighted in a poster titled "Liposomal Annamycin (L-ANN) Efficacy Against Primary and Metastatic Liver Cancers," presented by Dr. Waldemar Priebe, Lead Author and Chairman of the Scientific Advisory Board at Moleculin at the recently held Shelby-Lavine Pancreatic Cancer Symposium at MD Anderson Cancer Center.

Key Highlights

Targeted Accumulation in Organs: The preclinical studies confirmed that Annamycin exhibits distinct organotropic properties, leading to significantly higher concentrations in the liver, spleen, lungs, and pancreas when compared to doxorubicin (DOX). This targeted accumulation is critical for effectively treating liver-localized tumors.
Efficacy in Orthotopic Hepatocellular Carcinoma (HCC) Models: Annamycin demonstrated excellent anti-tumor activity in orthotopic HCC models (Hepa 1-6 Luc), showing a marked reduction in tumor progression and improved survival rates in treated animals compared to vehicle controls.
Potent Impact on Colorectal Liver Metastasis: In an experimental liver metastatic model of colorectal carcinoma (CT26 Luc), Annamycin significantly inhibited metastatic growth and extended survival, highlighting its potential for addressing liver metastases in colon cancer that affects close to 50% of patients.
Promising Results in Pancreatic Cancer Liver Metastasis: Annamycin also showed compelling efficacy in liver-implanted human pancreatic ductal adenocarcinoma (MIA PaCa-2), leading to inhibition of tumor growth, suggesting its potential role in managing advanced pancreatic cancer with liver involvement.
Favorable Safety Profile: Consistent with previous preclinical and clinical findings, Annamycin continued to show low or no cardiotoxicity, a significant advantage over traditional anthracyclines like doxorubicin, which are often limited by dose-dependent cardiac side effects. This safety profile was previously observed in clinical trials, where 32 out of 42 subjects reviewed received more than the FDA-established lifetime maximum allowable level of anthracycline without evidence of cardiotoxicity.
"We are incredibly encouraged by these preclinical results, which further validate Annamycin’s potential as a powerful and differentiated therapeutic agent for liver cancers," said Dr. Priebe. "The ability of Annamycin to concentrate effectively in the liver, combined with its demonstrated efficacy across multiple aggressive liver cancer models and its favorable cardiotoxicity profile, positions it as a highly promising candidate for patients facing these devastating diseases. We believe these data provide a strong foundation for advancing Annamycin in clinical development for these indications, offering new hope where treatment options are often limited."

Walter Klemp, Chairman and CEO of Moleculin, added, "We continue to be strongly encouraged by the potential of Annamycin. Beyond our preliminary programs in AML and soft tissue sarcoma lung metastases (STS lung mets), we continue to advance and develop Annamycin through multiple investigator-initiated studies to further unlock its potential as a treatment option for many other types of cancers. We believe this preclinical data highlights that potential and provides additional validation of its unique pharmacological profile and importantly showcases the opportunity for its use across a wide range of cancers."

Moleculin’s novel drug candidate is being positioned to become the first ever non-cardiotoxic anthracycline to be approved and is currently being developed for the treatment of AML and STS lung mets. For more information, please visit moleculin.com.