Resensitizing Treatment-Resistant Cancer Holds Promise Over Replacing Once-Efficacious Therapies
By John Yu, MD, CEO, Kairos Pharma
Modern oncology has made extraordinary strides over the past two decades. We have transitioned away from broad chemotherapies toward targeted therapeutics, precision diagnostics, and immunotherapies that turn once-fatal diagnoses into manageable conditions. Patients diagnosed with advanced prostate cancer or epidermal growth factor receptor (EGFR) mutant non-small cell lung cancer now routinely experience months or years of stable disease on first- and second-line targeted therapies.
Yet, despite these breakthroughs, cancer care faces a persistent biological wall. Even our most effective targeted treatments eventually lose their potency. When cancer cells adapt and treatment resistance emerges, the traditional response in drug development is to abandon the established drug and search for an entirely new therapeutic candidate.
This legacy paradigm of constant therapy replacement is inefficient and disconnected from biological reality. When a patient exhausts the efficacy of first- and second-line treatments, discarding the foundational regimen ignores the fact that the underlying drug mechanism was once extraordinarily successful.
Changing How We Think About Draining Efficacy
Standard-of-care therapies fail because tumor cells adapt under therapeutic pressure, shifting signaling pathways and altering their microenvironment to survive. We often forget that they often do not stop working because they were poorly designed. By abandoning these proven backbones, we force late-stage patients into high-risk trial settings, broad-spectrum salvage therapies, or palliative care.
A more pragmatic and biologically sound path forward for biotech and pharma companies should be to directly target the specific mechanisms of acquired resistance, restoring drug sensitivity to the very therapies that previously held the disease at bay.
Understanding the biology of acquired resistance reveals why this targeted strategy is so critical. Under the evolutionary pressure of therapy, cancer cells undergo molecular modifications to restore biological equilibrium.
In high unmet need settings like advanced prostate cancer and EGFR-mutant lung cancer, standard treatments such as anti-androgens, including enzalutamide, apalutamide, and abiraterone, or osimertinib deliver initial disease control. However, resistance develops in virtually all patients over time, frequently within 10 to 14 months in non-small cell lung cancer.
As these tumors adapt, they upregulate key protective drivers, including CD105, which acts as a shield against continued therapeutic exposure. The clinical consequences of this resistance loop are severe.
Prostate and lung cancers represent multibillion-dollar therapeutic markets, yet there are currently no FDA-approved treatments engineered specifically to reverse resistance once it emerges. When a patient progresses on osimertinib or anti-androgen therapy, clinicians face a stark clinical void with few viable options.
Shifting From Discovering The Next Therapy To Resensitizing Our Effective Ones
Abandoning these modern, highly potent backbones at the first sign of progression overlooks the clinical value already built into these regimens. Rather than forcing patients through endless cycles of increasingly toxic therapies, rising doses, and diminishing returns, our scientific community must focus on treatments designed to restore, rather than replace, established standards of care.
At Kairos Pharma, our clinical pipeline is built around this exact philosophy, and I implore more biotech and pharma companies to follow suit. Through our lead candidate, ENV105, we are testing whether blocking CD105 can resensitize resistant cancer cells to standard-of-care agents. Rather than acting as a stand-alone monotherapy to displace existing treatments, ENV105 is administered in combination with anti-androgens in prostate cancer and alongside osimertinib in EGFR-mutant lung cancer. Our ongoing randomized Phase 2 trial in prostate cancer and Phase 1 trial in non-small cell lung cancer are evaluating how intervention at the exact site of resistance can extend progression-free survival and restore sensitivity in refractory patient populations.
The clinical data gathered thus far confirms that resensitization is both biologically achievable and clinically tolerable. In prior prostate cancer clinical studies, pairing an anti-androgen with ENV105 achieved a 62% clinical benefit rate in resistant patients, notably without triggering grade four or five toxicities, and our latest interim data from the Phase 2 study showcases that median progression-free survival was more than 13 months, with many patients still continuing treatment.
Maintaining a clean safety profile is essential when treating patients who have already navigated multiple rounds of treatment. Additionally, supported by a $3.2 million-dollar National Institutes of Health grant, we have identified a three-gene biomarker signature that predicts patient responsiveness to ENV105. By coupling resistance-reversing therapeutics with precision biomarkers, we can ensure that patients who have exhausted standard options receive targeted, individualized interventions.
This combination strategy does not come without its own challenges, however. When you’re testing your candidate in combination with standard of care, your trial can face hurdles when that standard of care changes, forcing trial protocol changes and other headaches.
Future Implications Of A Target Resistance First Strategy
The broader implications of this strategy reach far beyond individual trials. Mechanisms of resistance, whether driven by tumor stem cells, macrophage reprogramming, or T-cell suppression, represent universal challenges across oncology and modern medicine. Preclinical research indicates that targeting resistance markers like CD105 can also resensitize models of colon, breast, and head and neck cancers that have acquired resistance to standard chemotherapy or radiation.
When we approach resistance as an actionable target rather than an inevitable endpoint, we create a reproducible blueprint for extending the life of modern therapeutics across oncology. The future of cancer drug development depends on our willingness to shift paradigms.
For patients facing high unmet need after failing first- and second-line therapies, abandoning effective standard-of-care treatments should no longer be the default. By learning how to target resistance mechanisms alongside existing standard-of-care therapies, even before the resistance begins to take hold, we can unlock new therapeutic life from proven drugs, deliver meaningful clinical benefit to vulnerable patients, and secure a more sustainable path forward for precision medicine.
About The Author:
John Yu, MD, is the founder and CEO of Kairos Pharma. Dr. Yu has spent his career at the intersection of neurosurgery, immunology, and cancer research, and also serves as professor of neurosurgery and director of surgical neuro-oncology at Cedars-Sinai Medical Center in Los Angeles. He earned his BAS from Stanford University and his MD from Harvard Medical School and MIT, completed his neurosurgery residency at Massachusetts General Hospital/Harvard, and pursued an immunology fellowship at the Institut Pasteur in Paris. This combined training in surgery and immunology has shaped his view of cancer as a complex biological system that can be retrained through immune-based strategies rather than isolated tumors to remove. Over the course of his career, Dr. Yu has developed eight FDA investigational drugs and holds multiple patents in immunotherapies and nanotechnologies, much of which stems from his NIH-funded laboratory at Cedars-Sinai. Prior to founding Kairos Pharma, he served as CEO and chairman of AcTcell and as director of Enviro Therapeutics.