The study found that CBX-12 displays pH selectivity, stability in plasma and selective delivery of exatecan to tumor cells versus healthy tissue. The selective delivery of exatecan to tumors led to extremely potent and durable anti-tumor activity in a range of xenograft models with minimal to no side effects relative to the unconjugated exatecan warhead, equimolar amounts of which are poorly tolerated.

“Dependence on antigens is a major barrier to the development of effective cancer therapeutics, and this study supports Cybrexa’s approach to delivering exatecan selectively to tumor cells in an antigen-independent manner,” said Vishwas Paralkar, Ph.D., Chief Scientific Officer of Cybrexa. “These findings are a major boost as CBX-12 advances through its first clinical trial, and we work toward making effective therapeutics available to more patients.”

CBX-12 is a novel treatment for solid tumors that includes a highly potent topoisomerase I inhibitor payload that is in the same class as the payloads used by antibody-drug conjugates (ADCs) ENHERTU® and TRODELVY™. In contrast to these ADCs, CBX-12 is able to target cancer cells independent of antigen expression, which could greatly expand the addressable patient populations. In May, Cybrexa initiated a Phase 1/2 clinical trial to evaluate CBX-12 in patients with advanced or metastatic refractory solid tumors to determine its safety and tolerability, maximum tolerated doses and dose limiting toxicities, and to establish the recommended Phase 2 dose.

CBX-12’s significantly enhanced therapeutic window relative to unconjugated exatecan enables combinations that were previously too toxic to use at efficacious doses, such as with DDR inhibitors. Because highly efficacious doses can be administered with minimal toxicity, this also provides the basis to explore novel combinations, such as with immunotherapies.

About the alphalex™ Technology Platform
The Cybrexa alphalex™ technology platform – which consists of a pHLIP® peptide, linker, and small molecule anti-cancer agent (payload) – enables antigen-independent targeting of tumors and intracellular delivery of highly potent anticancer therapies, creating therapeutics that can revolutionize the standard of care. pHLIP® peptides are a family of pH-Low Insertion Peptides that target acidic cell surfaces. pHLIP® was developed at Yale University and the University of Rhode Island, and is exclusively licensed to pHLIP, Inc. alphalex™ represents the disruptive next generation in tumor targeting. View a video of the mechanism of action of the technology at

About Cybrexa
Cybrexa is a privately-held biotechnology company dedicated to developing next-generation tumor-targeted cancer therapies using its alphalex™ platform. The Company’s lead candidate, CBX-12, an alphalex™-exatecan conjugate, is expected to enter Phase I/II in 2021 in advanced solid tumors. Cybrexa also has other preclinical toxin conjugate programs as well as synthetic lethality programs. Cybrexa was founded by physician-scientists and has an experienced management team that has built numerous successful life sciences companies. For more information about Cybrexa, please visit


Cybrexa Therapeutics
Lisa Rehm
Email: [email protected]

Investor Relations
Stephanie Carrington
Tel: 646-277-1282
Email: [email protected]

Media Relations
Mark Corbae
Tel: 203-682-8288
Email: [email protected]

Kyle Evans
Tel: 201-421-5061
Email: [email protected]