The tumor throws a cloak over itself, making it invisible to the body's defenses.
Among the most relentless of human cancers, glioblastoma has long confounded the immune system's best weapons — not by brute force alone, but by learning to disappear. Researchers at Massachusetts General Hospital and Harvard Medical School have traced one mechanism of that vanishing act to a molecule called Wnt7b, and have shown in preclinical models that silencing it, alongside standard immunotherapy, can restore the immune system's ability to see and destroy the tumor. The work represents not merely a new drug combination, but a deeper reckoning with how cancers engineer their own invisibility — and how that invisibility might, at last, be undone.
- Glioblastoma remains one of medicine's most urgent unsolved problems — fast-growing, treatment-resistant, and leaving most patients without viable options even as immunotherapy has transformed other cancers.
- A molecule called Wnt7b acts as a cloaking device inside these tumors, actively suppressing the immune response and explaining why anti-PD1 therapies, which work by releasing immune brakes, so often fail here.
- Combining the Wnt inhibitor WNT974 with anti-PD1 therapy in mouse models produced striking results — shrinking tumors, extending survival, and in some cases preventing recurrence entirely by simultaneously awakening immune sentries, activating killer T cells, and dismantling the tumor's defensive suppressor cells.
- Because WNT974 has already cleared a phase I safety trial in non-brain cancer patients, the path to human testing is shorter than it might otherwise be.
- Personalized clinical trials targeting glioblastoma patients with elevated Wnt7b signaling are now being planned, marking the transition from laboratory promise to potential clinical reality.
Glioblastoma kills with particular cruelty — growing fast, resisting treatment, and leaving patients with almost no good options. Standard immunotherapy, which works by unlocking the immune system to attack cancer, fails for most people with this brain tumor. Researchers at Massachusetts General Hospital and Harvard Medical School believe they have identified a key reason why, and have tested a potential solution in the lab.
The culprit is a molecule called Wnt7b, which runs at high levels in glioblastoma tumors and helps the cancer hide from the immune system. This cloaking effect explains why anti-PD1 therapy — designed to remove the brakes on immune cells — rarely helps glioblastoma patients: the immune system never gets a clear shot at the tumor to begin with.
Rakesh Jain, director of the Edwin Steele Laboratories for Tumor Biology, led a team that tested whether blocking Wnt7b could change that equation. Using a drug called WNT974 combined with anti-PD1 therapy in mouse models, the results published in the Proceedings of the National Academy of Sciences were striking: tumors shrank, survival extended, and in some cases tumors did not return. The mechanism was layered — blocking Wnt7b awakened dendritic cells, boosted killer T cell activity, and reduced the suppressor cells that normally shield the tumor, effectively pressing the accelerator while dismantling the tumor's defenses at once.
WNT974 has already been tested in a phase I trial for non-brain tumors and found to be safe, which shortens the road to human testing. Jain's team is now making the case for personalized clinical trials enrolling glioblastoma patients with elevated Wnt7b signaling. For a disease that has left most patients without viable paths forward, a therapy capable of overcoming immunotherapy resistance would not simply be another option — it could be transformative.
Glioblastoma kills with a particular cruelty: it grows fast, resists treatment, and leaves patients with almost no good options. The standard immunotherapy approach—drugs that unlock the immune system to attack cancer—fails for most people who get this brain tumor. Researchers at Massachusetts General Hospital and Harvard Medical School think they've found one reason why, and they've tested a fix in the lab.
The culprit is a molecule called Wnt7b. In glioblastoma tumors, this molecule runs at high levels, and it does something insidious: it helps the cancer hide from the immune system. The tumor essentially throws a cloak over itself, making it invisible to the body's natural defenses. This is why anti-PD1 therapy—a class of immunotherapy that normally works by removing the brakes on immune cells—doesn't help most glioblastoma patients. The immune system never gets a clear shot at the tumor in the first place.
Rakesh Jain, director of the Edwin Steele Laboratories for Tumor Biology at Massachusetts General Hospital, led a team that tested whether blocking Wnt7b could change that equation. They used a drug called WNT974, which inhibits Wnt signaling, and combined it with anti-PD1 therapy. The results, published in the Proceedings of the National Academy of Sciences, were striking. In mouse models of glioblastoma, the combination shrank tumors, extended survival, and in some cases prevented tumors from returning at all.
The mechanism matters. When the researchers looked closely at what was happening inside the treated tumors, they found that blocking Wnt7b did three critical things. First, it woke up dendritic cells—immune sentries that present tumor antigens to other immune cells, essentially sounding an alarm. Second, it boosted the activity of killer T cells, the immune system's assassins. Third, it reduced the number of suppressor cells that normally protect the tumor from attack. In other words, the combination therapy didn't just remove one brake; it simultaneously pressed the accelerator and dismantled the tumor's defenses.
WNT974 itself is not entirely new. It has already been tested in a phase I trial in patients with non-brain tumors and was found to be safe. That safety record matters because it means the drug could potentially move into human trials relatively quickly. Jain and his team are now making the case for personalized clinical trials—studies that would enroll glioblastoma patients whose tumors show elevated Wnt7b signaling and test whether the combination therapy works in people the way it worked in mice.
For glioblastoma patients, the stakes could hardly be higher. The disease remains one of the most aggressive human cancers, and the fact that standard immunotherapy doesn't work for most people has left them with few paths forward. A therapy that could overcome that resistance wouldn't just be another treatment option; it could be transformative. The next phase is clinical testing, and the researchers have made clear they believe the evidence warrants moving forward.
Notable Quotes
Targeting the Wnt7b/β-catenin pathway can sensitize glioblastoma to immune checkpoint blockade, offering a promising new therapeutic avenue.— Rakesh Jain, director of the Edwin Steele Laboratories for Tumor Biology at Massachusetts General Hospital
The Hearth Conversation Another angle on the story
Why does glioblastoma resist immunotherapy when it works for other cancers?
The tumor isn't just hiding—it's actively suppressing the immune system. Wnt7b acts like a chemical silencer, preventing immune cells from even recognizing the cancer is there.
So blocking Wnt7b alone wouldn't be enough?
Right. You need both pieces. Block Wnt7b to remove the suppression, then use anti-PD1 to activate the immune system. One without the other leaves the job half-done.
The mice that didn't develop tumors again—what does that tell you?
It suggests the immune system, once properly activated, can remember the tumor and prevent recurrence. That's the holy grail of cancer immunotherapy.
Why hasn't this been tested in patients yet?
Because preclinical work is just the beginning. You have to prove safety and efficacy in humans, and that takes time. But WNT974 already passed a safety trial, so the path forward is clearer than it might be for a completely new drug.
What happens if the clinical trials fail?
Then we learn something important about what works in mice versus humans, and researchers move on to other resistance mechanisms. But the biology here is solid—we know Wnt7b is elevated in glioblastoma patients, and we know it suppresses immunity. The question is whether blocking it in humans produces the same benefit we saw in the lab.