Smart drug that strips cancer cells of ‘invisibility cloak’ can shrink tumours by 30%, trial shows

A groundbreaking cancer treatment that strips tumors of their “invisibility cloak” has shown dramatic results in early trials, with some patients experiencing complete tumor elimination—even after other therapies failed. Two separate experimental drugs, one a tablet and another an injection, are delivering unprecedented responses in patients with advanced cancers, according to findings presented at the American Society of Clinical Oncology’s annual meeting in Chicago this week.

Two Drugs, One Radical Mechanism: How They Outsmart Cancer

The breakthroughs hinge on a shared strategy: dismantling the biochemical shields cancer cells use to evade the immune system. One drug, GRWD5769—a tablet developed by Oxford-based Greywolf Therapeutics—targets an enzyme called ERAP1, which tumors manipulate to hide from immunotherapy. The other, amivantamab (an injection from Johnson & Johnson), attacks tumors through three pathways: blocking growth signals, disrupting resistance mechanisms, and rallying the immune system to strike. Both are now in late-stage trials, with early data revealing responses that oncologists are calling “unprecedented.”

The drugs represent a shift from treating symptoms to dismantling cancer’s fundamental defenses. “For a drug that is given as a tablet, this is very impressive,” said Prof Fiona Thistlethwaite, lead investigator of the GRWD5769 trial, emphasizing the oral formulation’s convenience and the drug’s ability to “remove the invisibility cloaks” from tumor cells. Meanwhile, amivantamab’s trial results—presented at the same conference—showed 15 of 102 patients with head and neck cancer experiencing complete tumor disappearance, with responses visible within days. The Jerusalem Post reported that 43 patients saw tumor shrinkage or elimination, including those whose cancers had resisted chemotherapy and immunotherapy.

Trial Results That Defy Expectations: Numbers That Matter

The data defy the grim prognosis for patients whose cancers have progressed despite standard treatments. In the GRWD5769 trial—spanning the UK, France, Spain, and Australia—26 of 83 patients saw tumor shrinkage, with 15 achieving at least a 30% reduction. The drug worked across six cancer types: cervical, bladder, liver, bowel, lung, and head and neck. For liver cancer patients, 32% saw disease stabilization for six months; for lung cancer, the figure was 55%. The Guardian noted these results are particularly striking given that all participants had previously failed immunotherapy.

cluster (priority): The Independent

Amivantamab’s trial, meanwhile, targeted 102 patients with head and neck cancer—a group with historically poor outcomes after treatment failure. Here, 43 patients responded, including 15 whose tumors vanished entirely. Median survival after starting amivantamab was 12.5 months, a dramatic improvement for a cancer type where standard therapies often offer months at best. The drug is now being tested in 60 additional trials for lung, colorectal, brain, and gastric cancers, with early signals of efficacy in lung cancer as well.

Drug	Mechanism	Trial Response Rate	Key Cancer Types Tested
GRWD5769 (Greywolf Therapeutics)	Inhibits ERAP1 enzyme to expose tumors to immunotherapy	26/83 patients with tumor shrinkage; 15 with ≥30% reduction	Cervical, bladder, liver, bowel, lung, head/neck
Amivantamab (Johnson & Johnson)	Blocks growth receptors, disrupts resistance pathways, activates immune system	43/102 patients with tumor shrinkage/elimination; 15 with complete response	Head/neck (primary), lung, colorectal, brain, gastric (expanding)

What’s striking is the speed of response. Patients like Carl Walsh, 56, who joined the amivantamab trial after his tongue cancer returned, saw improvements within weeks. “I now feel able to live a normal life,” Walsh told The Guardian. “Before starting the trial, I struggled to speak properly and found eating difficult because of the swelling and pain. Since beginning treatment, the swelling has reduced significantly, and my pain levels have improved considerably.” His experience mirrors others in the trials, where quality-of-life improvements often precede measurable tumor changes.

Why This Matters: The Science Behind the Hype

The drugs’ success hinges on a fundamental flaw in cancer’s armor: its reliance on ERAP1 (for GRWD5769) and epidermal growth factor receptors (for amivantamab) to evade detection. Immunotherapy has revolutionized cancer care, but it fails in two-thirds of patients because tumors learn to hide. These new drugs force tumors back into the immune system’s crosshairs.

Kevin Harrington, a professor of biological cancer therapies at London’s Institute of Cancer Research, called the results “very striking” for a patient group with “extremely limited” options. “These are unprecedentedly strong responses in patients whose disease has become resistant to both chemotherapy and immunotherapy,” he said. The Independent highlighted Harrington’s estimate that the treatments could benefit “many thousands of patients each year” if approved.

The implications extend beyond survival rates. Both drugs are designed for oral or injectable administration, eliminating the need for invasive procedures like chemotherapy infusions. GRWD5769’s tablet form could improve adherence, while amivantamab’s rapid action (visible within days) offers hope for patients who’ve exhausted other options. Yet challenges remain: both drugs are still in trials, and long-term safety data are lacking. Side effects—ranging from immune-related reactions to skin rashes—will need careful monitoring as trials expand.

What Comes Next: The Path to Approval and Beyond

The next 12–18 months will be critical. Both drugs are poised for phase 3 trials, with regulatory submissions likely by 2027. If successful, GRWD5769 could become the first oral immunotherapy adjuvant, while amivantamab may carve out a niche for multi-targeted antibody therapies in resistant cancers. Johnson & Johnson, which acquired amivantamab’s developer earlier this decade, is already positioning it as a cornerstone of its oncology pipeline.

cluster (priority): The Jerusalem Post

The broader question is whether these results will translate into broader approvals—or if they’re outliers in a field where most breakthroughs fizzle in later trials. Historically, only about 10% of experimental drugs that show promise in early trials make it to market. Yet the consistency across cancer types and the speed of response suggest these may be exceptions. Oncologists are already debating whether such drugs could become first-line treatments for certain cancers, bypassing the need for chemotherapy entirely.

For patients like Walsh, the timeline is agonizing. “I’m very pleased with the progress,” he said, but added that the uncertainty of trial participation weighs heavily. The emotional toll of cancer treatment—especially when other options have failed—is a reminder that even groundbreaking science must balance hope with realism. As trials expand, the focus will shift from “Does it work?” to “For whom, and at what cost?”

One certainty: the race to develop similar therapies is accelerating. Companies are now screening for drugs that target other “invisibility mechanisms,” from metabolic pathways to DNA repair defects. If GRWD5769 and amivantamab succeed, they could redefine not just cancer treatment, but the very architecture of how tumors evade the body’s defenses.

For now, patients and oncologists alike will watch the trials closely. The data from Chicago offer a glimpse of a future where cancer’s most stubborn forms can be exposed—and destroyed.