On November 12, 2026 Racura Oncology Limited (ASX: RAC), a late clinical-stage biopharmaceutical company developing new small molecule-based approaches to cancer treatment focused on silencing MYC gene expression, reported that new preclinical data on the MYC-directed mechanism of action of (E,E)-bisantrene are being presented as a poster at the Frontiers in Cancer Science (FCS) 2026 Conference, held in Singapore from 11–13 November 2026. The data show that (E,E)-bisantrene is the major active isomer (molecular form) of bisantrene able to stabilize the G-quadruplex in the MYC gene promoter region, leading to reduced MYC gene expression and MYC protein levels.

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In these preclinical studies, light exposure converted (E,E)-bisantrene into less active isomers, which resulted in significantly less MYC G-quadruplex stabilization and a lowering of the inhibition of MYC gene expression.

In the study, exposing (E,E)-bisantrene to blue (440 nm) light reduced its content in solution to approximately 60% after 15 minutes, approximately 40% after one hour and an unquantifiable level after four hours. In MDA-MB-231 breast cancer cells, pure (E,E)-bisantrene suppressed MYC gene expression with a half-maximal effective concentration of 277 nM, compared with 514 nM to 1,166 nM for the light-exposed isomer mixtures, and reduced cancer cell viability with a half-maximal inhibitory concentration of 266 nM, compared with 310 nM to 825 nM for the mixtures. An isomer mixture containing 62% (E,E)-bisantrene stabilized the MYC G-quadruplex significantly less than pure (E,E)-bisantrene at the same concentration, and stabilization was restored when the amount of (E,E)-bisantrene was matched.

These findings build on the MYC gene expression inhibition data for (E,E)-bisantrene presented at the 2026 American Association for Cancer Research (AACR) (Free AACR Whitepaper) Annual Meeting in April 2026 and further support the importance of the MYC-directed mechanism of action of RC220. Racura continues to investigate this mechanism through its ongoing research collaboration with Purdue University.

The poster is entitled "Light-Induced Isomerization Attenuates (E,E)-Bisantrene G-Quadruplex Binding and MYC Silencing" and reports work by Racura scientists and collaborators at the University of Wollongong, Australia.

Daniel Tillett, Ph.D., Chief Executive Officer of Racura Oncology, said: "These data show that (E,E)-bisantrene is the form that stabilizes G-quadruplex structures and inhibits MYC gene expression. Bisantrene can exist as several isomers, and confirming that the (E,E)-isomer is the active form supports our development of RC220 as a proprietary formulation of (E,E)-bisantrene. While these are preclinical findings, they add to the growing body of evidence for the MYC-directed mechanism of action of RC220."

Scientific Rationale

RC220 is being clinically developed to target non-canonical G-quadruplex DNA and RNA structures enriched in oncogenic regulatory regions, including promoters, untranslated regions and highly transcribed loci. Stabilization of these structures can disrupt transcriptional and post-transcriptional control networks that sustain malignant proliferation, including the silencing of MYC-driven growth and survival pathways.

(E,E)-bisantrene contains two hydrazone groups that can isomerize, and exposure to light converts it into (E,Z)- and, it is postulated, (Z,Z)-isomers. The FCS 2026 data indicate that the (E,E)-isomer is the form most responsible for MYC G-quadruplex stabilization, MYC suppression and anticancer activity, supporting Racura’s development of RC220 as a proprietary formulation of (E,E)-bisantrene.

About RC220 & (E,E)-bisantrene

RC220 is a proprietary formulation of (E,E)-bisantrene designed to overcome drug solubility issues that prevent safe peripheral intravenous infusion. (E,E)-bisantrene is a clinically validated small molecule anticancer agent that primarily functions via G4-DNA and RNA binding, leading to potent transcriptional silencing of the important cancer growth regulator MYC and downstream pathways.

(Press release, Racura Oncology, NOV 12, 2026, View Source [SID1234674709])