Tebentafusp Doubles 5-Year Survival, but HLA-Negative Patients Still Wait

Five-year overall survival reached 16% with tebentafusp versus 8% with investigator's choice in the IMCgp100-202 trial, giving clinicians in metastatic uveal melanoma their first realistic shot at long-term survival — but most patients still need what comes next.

The field's next act is split across two fronts: liquid biopsy as a decision tool, and a non-HLA-restricted combination that more than doubled median progression-free survival. Darovasertib plus crizotinib delivered a median PFS of 6.9 months versus 3.1 months for investigator's choice in HLA-A*02:01–negative disease in the OptimUM-02 trial, presented at the 2026 ASCO annual meeting (J Clin Oncol. 2026;44[suppl 17]:LBA9503).

The IMCgp100-202 five-year data were published by Piperno-Neumann and colleagues in Annals of Oncology (2026;37[9]:1266-1277). Together, the two datasets frame the current treatment conversation.

What can ctDNA add when scans mislead?

Circulating tumor DNA can confirm a patient is benefiting from tebentafusp even when imaging shows little shrinkage or slight lesion growth, the expert explained. That matters because tebentafusp responses often don't follow classic RECIST patterns.

But the tool has limits. Not every patient has detectable ctDNA or cfDNA at baseline. And prospective validation is lagging.

"We need a very large study to say we are going to use ctDNA as one of our primary or co-primary end points," the expert said. Right now, investigators embed ctDNA mostly as secondary aims, with results analyzed months after trials close.

Real-time, contemporaneous ctDNA reporting that reaches physicians as fast as a CT or MRI — and proves better than RECIST — remains unachieved. "We have yet to get high-quality data to say this is better than RECIST," the expert said.

In practice, ctDNA is used selectively, not universally. Sometimes scans or improving symptoms speak for themselves.

How much does HLA-A*02:01 status matter?

It matters enormously, because tebentafusp's FDA approval and most ongoing antigen-targeting trials — including those against PRAME — require HLA-A*02:01. Roughly 40% of people carry it even in the most enriched populations of Northern and Western Europe.

Geography widens the gap:

• Northern/Western Europe: about 60% lack the allele
• New York City: only 30% to 35% carry it
• Brazil: about 20% carry it
• East Asia: also quite low

Clinicians, the expert argued, carry "a moral imperative" to push non-HLA-restricted treatments with a solid scientific basis, because those can reach everybody. Extending HLA-specific approaches to other alleles like 03:01, 01:01 or 29:02 remains years away — each is a different molecule requiring years of proof.

Why does uveal melanoma develop drugs on a separate track?

Nearly all uveal melanomas are driven by GNAQ or GNA11 mutations, with CYSLTR2 alterations less common. Until recently, no targeted treatment could durably shrink or stabilize disease.

Darovasertib plus crizotinib changes that calculus by hitting the PKC and MET signaling pathways those mutations activate. By contrast, 99% of cutaneous melanomas don't use those pathways, so PKC and MET inhibition won't work for them. The exception is the roughly 1% of skin melanomas — malignant blue nevus–type tumors with distinct histology and genomic subsets — now being carved out for dedicated trials.

How big is the OptimUM-02 benefit, really?

"The magnitude of PFS benefit with darovasertib and crizotinib is extremely significant. It is, by any sense in modern clinical oncology, an advance," the expert said.

The right end of the curve matters more than the median for patients asking how long a treatment can realistically work. The chance of staying on therapy for one or two years is life-changing — the same shift tebentafusp delivered.

The regimen isn't for everyone; patients should discuss fitness and readiness with their physician. IDEAYA Biosciences, in its November 3, 2026 third-quarter business update, advanced the program toward an expected FDA decision. "Hopefully [there will be] an FDA approval in 2027, which is what we're all openly rooting for, and I would be shocked if that didn't happen," the expert said.

Could darovasertib go neoadjuvant for eye preservation?

A significant minority of patients can't receive radiation and face enucleation. A drug that quickly shrinks the primary tumor could allow globe salvage, radiation of a smaller visual field, and better long-term vision.

It's a familiar pattern across solid tumors: prove benefit in stage IV, then move the drug earlier. Darovasertib is among the first tools the uveal melanoma field broadly believes could work in the neoadjuvant setting.

Compared with a little over a decade ago, the pace of improvement in uveal melanoma is accelerating — and if 2027 delivers a second frontline approval, that curve steepens again.