UCLA Finds E2F3 Weakness in RB-Deficient Cancers, Flagging 2 FDA-Approved Drugs

Q: After decades of stalled progress, what technology finally cracked the code for these notoriously resistant neuroendocrine tumors?

The breakthrough came from genome-wide CRISPR screening, made possible by newly built human organoid and mouse tumor models that accurately mimic these cancers. UCLA researchers said progress had been stalled for decades largely because aggressive small cell neuroendocrine tumors were difficult to model in the lab. To solve that, they genetically engineered normal human prostate cells with key cancer-driving changes, grew them into organoids, and then generated tumors in mice. Those models gave them a realistic system for testing what the tumors need to survive. Using that platform, they ran genome-wide CRISPR screens and identified a key vulnerability: RB-deficient small cell cancers become critically dependent on E2F3. That exposed a synthetic lethal relationship—loss of RB alone is tolerated, but disrupting E2F3 kills the cancer cells. The finding matters because it points to a treatment strategy for tumors in the lung, prostate, and ovary that have long resisted standard therapies. Although there is no direct E2F3 drug yet, the team showed that inhibiting DHODH can lower E2F3 levels and slow tumor growth. Because DHODH inhibitors such as leflunomide and teriflunomide are already FDA-approved for autoimmune diseases, they could potentially be tested more quickly in cancer patients. In short, it was the combination of advanced organoid-based disease models and genome-wide CRISPR technology that finally cracked the code.

Q: An autoimmune drug may halt deadly cancers. When will human trials for this repurposed therapy begin?

There is no announced start date yet for human trials of the repurposed therapy. The UCLA study, published March 20, 2026, showed in lab models and mice that RB-deficient small cell neuroendocrine cancers depend on E2F3, and that DHODH inhibitors can lower E2F3 and slow tumor growth. Because leflunomide and teriflunomide are already FDA-approved for autoimmune diseases, researchers say they could move into cancer testing faster than a brand-new drug. But the available reporting and supporting material do not identify an active or scheduled clinical trial in patients for this specific approach. The work remains preclinical, and the researchers have only said the findings “open the door” to using existing drugs in a new way and may allow strategies to reach patients more quickly. So the most accurate answer is that human trials have not yet been publicly scheduled, at least based on the information now available. The next likely step would be an early-phase cancer trial to test safety, dosing, and whether DHODH inhibitors such as leflunomide or teriflunomide show activity in patients with these aggressive neuroendocrine cancers.

1 articles · Updated · SciTechDaily · Jun 9

PNAS findings show RB-deficient small-cell neuroendocrine cancers in the lung, prostate and ovary depend on E2F3, and blocking that protein halted tumor growth in lab experiments.
Genome-wide CRISPR screens using new prostate cancer organoid and mouse models identified nearly 1,400 survival genes, with E2F3 emerging as a shared dependency across small-cell cancers from different organs.
Further tests found suppressing E2F3 stopped RB-deficient cells from dividing, prevented cluster formation and in some cases killed them, defining a synthetic-lethal weakness in tumors long resistant to targeted therapy.
Because no drug directly targets E2F3, the team turned to DHODH inhibition; leflunomide and teriflunomide—2 FDA-approved autoimmune drugs—lowered E2F3 levels and slowed tumor growth.
The study remains early-stage, but researchers say the result could open a faster path to new treatments for cancers whose survival rates have changed little for decades.

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SciTechDaily11h ago

UCLA Scientists Uncover E2F3 Vulnerability in Aggressive RB-Deficient Cancers

After decades of stalled progress, what technology finally cracked the code for these notoriously resistant neuroendocrine tumors?

This protein drives multiple aggressive cancers. What is the biggest hurdle to developing a direct drug to block it?

An autoimmune drug may halt deadly cancers. When will human trials for this repurposed therapy begin?

Exploiting RB Gene Loss: Repurposing DHODH Inhibitors for Aggressive Small Cell Neuroendocrine Cancers

Overview

UCLA researchers have made a major breakthrough by uncovering a hidden vulnerability in some of the most aggressive and deadly cancers. This discovery reveals a new way to target tumors that have resisted existing treatments for years. For decades, patients with these cancers had very limited options, making the search for new therapies urgent. Now, this finding opens the door to entirely new treatment strategies and offers hope for innovative interventions. By identifying this critical weakness, scientists are providing a fresh perspective on how to fight cancers that have long been difficult to treat.

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SciTechDaily11h ago

UCLA Scientists Uncover E2F3 Vulnerability in Aggressive RB-Deficient Cancers

UCLA Finds E2F3 Weakness in RB-Deficient Cancers, Flagging 2 FDA-Approved Drugs

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Exploiting RB Gene Loss: Repurposing DHODH Inhibitors for Aggressive Small Cell Neuroendocrine Cancers

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