We've known it helps tumors hide, but until now, attempts to target it have failed.
For decades, oncologists have watched promising immunotherapies falter against tumors that learned to hide behind a molecular cloak — a protein called TGFβ1 that silences the immune system's call to arms. Now, a Phase I trial at MD Anderson Cancer Center suggests that a precisely engineered antibody, linavonkibart, may have found a way through that barrier without the toxicities that doomed earlier attempts. In a field where resistance has long been the final word, this moment represents not a cure but a door — one that researchers believe may open wider the earlier it is used.
- Tumors have long exploited TGFβ1 as a shield against immunotherapy, and every prior attempt to block it caused harm by disrupting proteins the body cannot do without.
- Linavonkibart's selective design — locking only TGFβ1 in an inactive state using fully human protein structures — breaks that deadlock without triggering the severe toxicities that ended earlier programs.
- The trial enrolled 112 patients with a median life expectancy of three months, making every response signal carry extraordinary weight against a backdrop of near-exhausted options.
- A 20% response rate in advanced renal cell cancer, alongside responses in melanoma, head and neck, and urothelial cancers, emerged with only four grade-four adverse events in the largest cohort.
- Researchers now believe the real test lies ahead — in earlier-line patients whose resistance has not yet hardened — where the combination may prove substantially more powerful.
At MD Anderson Cancer Center, a Phase I trial has produced one of the more consequential findings in cancer immunotherapy in recent years: an antibody that may finally crack the resistance mechanism tumors use to hide from the immune system. Published in Nature Medicine, the study centers on linavonkibart, a monoclonal antibody designed to neutralize TGFβ1 — a protein that acts as a molecular cloak, shielding tumors from immune detection.
The challenge this drug addresses has frustrated oncologists for years. Immunotherapies like pembrolizumab work by releasing the immune system's brakes, but many cancers either never respond or develop resistance over time. Scientists identified TGFβ1 as a key culprit long ago, yet every attempt to block it also disrupted two related proteins — TGFβ2 and TGFβ3 — that the body depends on for normal function, producing toxicities that made treatment untenable. Linavonkibart sidesteps this by binding exclusively to TGFβ1 and locking it permanently inactive, while its fully human protein architecture improves tolerability over earlier, partly animal-derived antibodies.
The 112 patients enrolled were among the most difficult cases imaginable — heavily pretreated individuals with a median prognosis of just over three months. The trial moved through dose escalation of linavonkibart alone, then in combination with pembrolizumab, before settling on an optimal dose for a larger expansion cohort. The safety profile held: rash was the most common serious side effect, only four patients experienced grade-four adverse events, and no dose-limiting toxicities forced a halt.
Efficacy signals were meaningful given the population. In advanced clear cell renal cell cancer, 20% of patients responded — a striking figure for people who had exhausted prior options. Responses also appeared in melanoma, head and neck squamous cell cancer, and urothelial cancer. Biomarker analyses suggested that patient selection could be refined further, potentially concentrating benefit where it is most likely to occur.
Trial lead Timothy Yap framed the results as a beginning rather than an endpoint. The patients enrolled represented the hardest test — those with the deepest, most entrenched resistance. The working hypothesis for what comes next is that linavonkibart will perform even better when introduced earlier, before resistance has had time to consolidate. First presented at the 2024 ASCO annual meeting, the full published data now position this antibody as a credible candidate to address one of immunotherapy's most persistent limitations.
Researchers at MD Anderson Cancer Center have identified a new way to break through one of immunotherapy's most stubborn obstacles: cancers that refuse to respond to the drugs designed to wake up the immune system. The answer, according to a Phase I trial published in Nature Medicine, lies in a monoclonal antibody called linavonkibart, which targets a specific protein that tumors use to hide from the body's defenses.
The problem linavonkibart addresses is well-known to oncologists. Immunotherapies like pembrolizumab have transformed cancer treatment by releasing the brakes on immune cells, allowing them to recognize and attack tumors. But many cancers either never respond to these drugs or develop resistance over time. Research has pointed to a culprit: a protein called transforming growth factor-beta 1, or TGFβ1, which acts like a cloak, helping tumors evade immune detection. Scientists have wanted to block this protein for years, but earlier attempts ran into a wall. Those drugs targeted not just TGFβ1 but also two related proteins, TGFβ2 and TGFβ3, which the body needs for normal function. The result was severe toxicity that made the treatment worse than the disease.
Linavonkibart takes a different approach. It is selective—it binds only to TGFβ1 and locks it in an inactive state, preventing it from ever switching on. Because it is built entirely from human protein structures, the body should tolerate it better than previous antibodies, which were partly derived from other species. Timothy Yap, who led the trial, called the development a breakthrough after decades of failed attempts. "We've known that it helps tumors evade the immune system and develop resistance to immunotherapies but, until now, attempts to target it have failed," he said.
The trial enrolled 112 heavily pretreated cancer patients—people who had already tried multiple lines of therapy and were running out of options. Their median life expectancy was just over three months. The study had three phases: patients received linavonkibart alone, then linavonkibart combined with pembrolizumab in escalating doses, and finally a larger group received the combination at the optimal dose. The safety profile was manageable. The most common serious side effect was rash, and only four patients in the largest group experienced grade four adverse effects. No dose-limiting toxicities emerged that would have forced researchers to stop the trial.
The efficacy signals were encouraging. Among the 78 patients in the dose expansion cohort, physicians observed multiple objective responses—tumors that shrank or disappeared. The most striking result came in advanced clear cell renal cell cancer, where 20 percent of heavily pretreated patients responded. Responses also appeared in melanoma, head and neck squamous cell cancer, and urothelial cancer. Exploratory biomarker studies suggested researchers may be able to identify which patients are most likely to benefit, potentially allowing for smarter patient selection in future trials.
What comes next is perhaps the most intriguing question. Yap noted that the Phase I trial deliberately enrolled the sickest patients—those with the most advanced resistance to immunotherapy. The hypothesis driving future work is that linavonkibart will prove even more effective if given earlier, before tumors have had time to develop deep resistance. "We believe that this linavonkibart combination will be even more effective when given in earlier treatment settings, before significant resistance to immunotherapy has developed," Yap said. The trial data were first presented at the 2024 American Society of Clinical Oncology annual meeting, and the full results now published suggest the field may finally have a tool to overcome one of cancer immunotherapy's most persistent limitations.
Citas Notables
We've known that it helps tumors evade the immune system and develop resistance to immunotherapies but, until now, attempts to target it have failed. This is potentially a significant step in helping patients overcome resistance and benefit further from immunotherapies.— Timothy Yap, MD Anderson Cancer Center
We believe that this linavonkibart combination will be even more effective when given in earlier treatment settings, before significant resistance to immunotherapy has developed.— Timothy Yap
La Conversación del Hearth Otra perspectiva de la historia
Why did previous attempts to block this TGFβ protein fail so badly?
Because they were too blunt. They blocked TGFβ1, but also TGFβ2 and TGFβ3—proteins the body actually needs to function normally. Patients got too sick to continue treatment.
And linavonkibart is different because it's selective?
Exactly. It only targets TGFβ1. It's like the difference between a sledgehammer and a scalpel. The selectivity is what makes it tolerable.
The response rate of 20 percent in renal cancer—is that good?
In this population, yes. These are people who've already failed multiple treatments and have three months to live. Any response is meaningful. But the real excitement is that this might work better earlier, before resistance sets in.
Why would it work better earlier?
Because the tumor hasn't had time to build up multiple layers of immune evasion. You're hitting the resistance mechanism before it becomes entrenched. It's preventive rather than rescue therapy.
What's the risk of moving to earlier-line treatment?
You're treating more patients, including some who might have responded to standard therapy alone. But if the combination is safe and more effective, the benefit likely outweighs that concern.