New Pancreatic Cancer Treatment Eliminates Tumors and Prevents Drug Resistance

Pancreatic cancer is the deadliest major malignancy in the developed world. Its five-year survival rate — stuck at a grim 13% — has barely budged in a generation, and the disease is projected to kill more than 52,000 Americans this year alone [1]. Treatments that initially show promise almost invariably fail as tumors evolve resistance within months, rendering drugs useless. Now, a team of Spanish researchers has achieved something that has eluded oncology for decades: complete tumor elimination in animal models with no resistance developing, even after nearly seven months of observation.

The findings, published in the Proceedings of the National Academy of Sciences (PNAS) in January 2026, come from the laboratory of Mariano Barbacid at Spain's National Cancer Research Centre (CNIO) — a scientist who has spent his career pursuing the oncogene at the heart of pancreatic cancer [2][3]. The approach is deceptively simple in concept, though fiendishly difficult in execution: block the KRAS signaling pathway at not one, but three separate points, so the cancer has nowhere to run.

The 'Undruggable' Gene That Drives 90% of Pancreatic Cancers

To understand why this research matters, you have to understand KRAS — and why it has been oncology's most frustrating adversary for more than 40 years.

KRAS was identified as one of the first driver oncogenes in human cancer in the early 1980s [4]. Mutations in the KRAS gene are found in approximately 90% of pancreatic ductal adenocarcinoma (PDAC) cases, the most common and lethal form of pancreatic cancer [5]. The protein it encodes acts as a molecular switch, transmitting signals that tell cells to grow and divide. When KRAS is mutated, that switch gets stuck in the "on" position, driving relentless, uncontrolled tumor growth.

For nearly four decades, KRAS was labeled "undruggable." The protein's surface was smooth, lacking the deep pockets where drug molecules typically bind. Its affinity for GTP — the energy molecule that activates it — was extraordinarily high, making it nearly impossible for a competing drug to shoulder its way in [4].

The first crack in the wall came in 2013, when researchers at the University of California, San Francisco discovered a previously hidden pocket on the surface of one specific KRAS mutant, G12C. This led to the development of sotorasib and adagrasib, the first KRAS inhibitors to receive FDA approval in 2021 and 2022 respectively — but for lung cancer, not pancreatic [4]. The G12C mutation is common in lung cancer but extremely rare in pancreatic tumors, occurring in only 1-2% of PDAC cases. The dominant KRAS mutation in pancreatic cancer is G12D, which remained beyond therapeutic reach.

The emergence of a new class of drugs called RAS(ON) multi-selective inhibitors has begun to change that picture. Daraxonrasib (formerly RMC-6236), developed by Revolution Medicines, can target multiple KRAS mutations — including G12D — and has received FDA Breakthrough Therapy Designation for previously treated metastatic pancreatic cancer [6]. Multiple Phase 3 clinical trials are now underway.

The Three-Pronged Attack

But the CNIO team's insight was that even a powerful KRAS inhibitor, used alone, was destined to fail. Cancer cells are evolutionary machines. Block one pathway, and they will find another route to survival — often within months.

"Overcoming therapeutic resistance in PDAC requires coordinated inhibition of KRAS downstream, upstream, and parallel survival pathways," the researchers wrote in PNAS [2].

Their solution was a triple-drug combination that simultaneously attacks three critical nodes in the signaling network:

1. Daraxonrasib — the experimental KRAS inhibitor that blocks the oncogene's primary downstream signaling through RAF1
2. Afatinib — an already-approved drug for certain lung adenocarcinomas that irreversibly inhibits the EGFR family of receptors, cutting off the upstream signals that can reactivate KRAS
3. SD36 — a PROTAC (proteolysis targeting chimera) protein degrader that destroys STAT3, a parallel survival pathway that tumors can hijack when the main KRAS route is blocked

The logic is straightforward: if you close every escape hatch, the tumor has no way to develop resistance.

Complete Elimination, Zero Resistance

The results were striking. The CNIO team tested the triple combination in three separate mouse models of pancreatic ductal adenocarcinoma, including genetically engineered mice with KRAS and TP53 mutations — the same genetic landscape seen in most human PDAC patients — and patient-derived xenografts [2][3].

In every model, the treatment triggered complete tumor regression. "You couldn't even see where the tumor was," the researchers reported. "The pancreas was completely healthy" [3].

More remarkably, the tumors did not return. The mice were monitored for more than 200 days — nearly seven months — after treatment, with no evidence of tumor regrowth or resistance [2]. In a disease where treatments typically stop working within months, this durability was unprecedented.

The triple combination was also well tolerated, causing no significant toxicities in the animal models — a critical finding, since combination therapies often compound side effects to intolerable levels [7].

"Although experimental results like those described here have never been obtained before, we are still not in a position to carry out clinical trials with the triple therapy," Barbacid cautioned [3]. The gap between mouse models and human patients remains vast, and each component of the triple therapy must be optimized for human use.

Source: GDELT Project

Data as of Mar 15, 2026CSV

The Stubborn Reality of Pancreatic Cancer Survival

The urgency of this research is underscored by the stagnation in pancreatic cancer outcomes. While overall cancer survival rates in the United States have reached a milestone 70% five-year survival, pancreatic cancer remains stranded at 13% — the only major cancer with a five-year survival rate below 20% [1][8].

The numbers are even bleaker when broken down by stage. Only about 15% of patients are diagnosed with localized disease, where the five-year survival rate has climbed to 44%. But for the majority who present with distant metastatic disease, the five-year survival rate has crawled from 2% to just 3% over two decades [8].

In 2026, an estimated 67,530 Americans will be diagnosed with pancreatic cancer, and 52,740 are expected to die from it [1]. The disease is on track to become the second-leading cause of cancer death in the United States, surpassing colorectal cancer, within the coming years.

Source: American Cancer Society / SEER

Data as of Mar 15, 2026CSV

A Broader Landscape of Progress

The CNIO study does not exist in isolation. It arrives amid a surge of activity in pancreatic cancer research that, while still far from producing a cure, represents the most concentrated effort against the disease in history.

Daraxonrasib in human trials. Revolution Medicines is running three Phase 3 clinical trials for daraxonrasib in pancreatic cancer: RASolute 302, testing the drug as a monotherapy against standard chemotherapy in previously treated metastatic PDAC; RASolute 303, studying it in first-line metastatic disease; and RASolute 304, evaluating it as an adjuvant treatment after surgery [6]. Early data from the Phase 1/1b trial showed "promising clinical activity and durability" that earned FDA Breakthrough Therapy Designation in July 2025 and Orphan Drug Designation in October 2025 [6].

Immunotherapy combinations. At NewYork-Presbyterian, the Chemo4METPANC trial is combining chemotherapy with a CXCR4 inhibitor (motixafortide) and an immune checkpoint inhibitor (cemiplimab). In an initial pilot of 11 patients, nearly two-thirds showed tumor responses — far exceeding the typical response rate for chemotherapy alone [9]. Meanwhile, Northwestern University researchers have developed an antibody therapy that "reawakens" the immune system to recognize and attack pancreatic tumors [10].

Oncolytic virus therapy. The FDA granted Fast Track Designation to VCN-01, an oncolytic virus that replicates within tumor cells and breaks down the dense stromal barrier that shields pancreatic tumors from treatment. It is being studied in the VIRAGE trial in combination with chemotherapy for metastatic patients [11].

UCLA's universal immunotherapy. Researchers at UCLA have developed a "one-product-fits-all" immunotherapy approach specifically designed for pancreatic cancer, potentially offering an off-the-shelf treatment that could bypass the need for patient-specific cell manufacturing [12].

The Funding Question

Progress in pancreatic cancer research remains constrained by funding that critics say is disproportionate to the disease's lethality. The National Cancer Institute currently allocates approximately $237.6 million annually to pancreatic cancer research — roughly 3% of its $7.35 billion total budget [13]. By comparison, breast cancer, which has a 91% five-year survival rate, receives substantially more.

The Pancreatic Cancer Research Program (PCARP), a Department of Defense initiative, was reinstated in fiscal year 2026 with $20 million — its largest allocation ever, but still a fraction of what advocates argue is needed [13]. These gains came against a backdrop of the Trump administration's proposed 37% cut to NIH funding, which Congress ultimately rejected, maintaining flat funding levels [13].

The CNIO study itself was funded by a consortium of European sources, including the Fundación CRIS Contra el Cáncer, the European Research Council, and the Spanish State Research Agency [3] — a reminder that some of the most consequential cancer research is happening outside the United States.

From Mice to Patients: The Hard Road Ahead

The CNIO team's results are genuinely unprecedented in pancreatic cancer research. No prior study has achieved complete tumor elimination with no resistance in multiple animal models of this disease. But the chasm between mouse experiments and clinical treatment remains formidable.

SD36, the STAT3 degrader in the triple combination, is not yet approved for human use and would require its own extensive safety testing before it could be deployed in patients. The optimal dosing, sequencing, and duration of the triple combination for humans are unknown. And the dense tumor microenvironment of human pancreatic cancers — the fibrous stroma that acts as a physical barrier to drug delivery — may present challenges that mouse models do not fully replicate.

"These studies open the road to design novel combination therapies that may improve the survival of PDAC patients," the authors wrote [2]. Barbacid's group and others are now working to identify which components of the triple therapy could be substituted with drugs already in clinical development, potentially accelerating the timeline to human trials.

The convergence of KRAS inhibitor development, immunotherapy advances, and the CNIO's resistance-blocking strategy offers a more comprehensive toolkit against pancreatic cancer than has ever existed. Whether that translates to meaningful survival gains for patients will be determined in clinical trials over the coming years. For the more than 67,000 Americans diagnosed annually with this disease, the wait is measured not in scientific timelines but in months of remaining life.

Source: SEER Cancer Statistics

Data as of Mar 15, 2026CSV