Iovance Stock Crashes 35%: Lung Cancer Data Left One Big Question Unanswered

Iovance Biotherapeutics stock crashed 35.45% on Thursday, October 29, 2026, closing at $9.56, after updated lung cancer data for lifileucel showed a 24.6% response rate in 69 patients — and left how long those responses last unanswered. The fall, from a $14.81 prior close, made Iovance the day's biggest biotech loser, on volume of about 59 million shares, roughly three and a half times its usual pace.

What happened?

Iovance released updated results from its IOV-LUN-202 trial of lifileucel in previously treated, non-squamous metastatic non-small cell lung cancer. In 69 patients, 24.6% responded to treatment. That was essentially unchanged from 25.6% in an earlier cut of 39 patients, and it is roughly double the 12% to 15% response rate typically seen with docetaxel, the standard second-line treatment for this condition.

The split by tumor type was sharp. Patients with KRAS wild-type tumors responded at 43.3%, while those with KRAS-mutant tumors responded at just 11.4%. Reports on the fuller dataset also pointed to a 59.1% response rate in a small biomarker-enriched subgroup — but that subgroup was only 22 patients, identified retrospectively, which makes it a hypothesis to test rather than a proven result.

Why did the stock fall 35% if the response rate held up?

The missing number was durability. Iovance did not say how long responses lasted, and it did not lay out detailed safety and tolerability results. Both were covered by a single line in the release: response durability and the safety profile remained consistent with previous reports.

That gap matters because durability is the whole argument for this kind of therapy. Lifileucel is a tumor-infiltrating lymphocyte, or TIL, therapy: doctors take a piece of a patient's tumor, grow huge numbers of immune cells from it, and infuse them back after a lymphodepletion process that weakens the immune system. If responses fade in a few months, the treatment looks much less different from chemotherapy. If they last well over a year, it looks very different.

Company executive Brian Gastman told Investor's Business Daily that critics were taking a "cup half empty" view, saying median durability has never been reached and that it looks likely to be well over a year — while also conceding the data are immature and the company still does not know. Investors, faced with a promise instead of a number, sold first.

Why it's blowing up

Context made the drop bigger. Iovance shares carried a perfect Relative Strength Rating of 99, meaning they had performed in the top 1% of all stocks over the past 12 months, and the stock had run up hard into the readout. The company had described the results in advance as "positive" and scheduled a webcast to unveil them, which raised expectations further. When the headline number merely matched the earlier cut and the key durability figure was absent, there was a long way to fall — the close of $9.56 sits well inside a 52-week range of $1.76 to $15.37.

There is also a history investors remember. The lung cancer study was paused in December 2023 after a patient died, potentially tied to lymphodepletion; regulators allowed dosing to resume at a lower lymphodepletion dose. Skeptics have argued that change might have weakened effectiveness. Gastman said the similar response rate should settle that debate — but without durability data, the debate stayed open for another day.

Key facts

Move: Down 35.45% to $9.56 on October 29, 2026, from $14.81, on about 59 million shares.
Response rate: 24.6% in 69 non-squamous lung cancer patients, versus 25.6% in the earlier 39-patient cut.
Subgroups: 43.3% in KRAS wild-type tumors; 11.4% in KRAS-mutant tumors.
Missing: No duration-of-response figure and no detailed safety breakdown in the release.
Next steps reported: A supplemental filing is planned for 2027, alongside a biomarker-focused strategy; enrollment toward about 80 patients is the bar the company has cited for seeking approval.
Already approved: Lifileucel, sold as Amtagvi, is approved for melanoma that cannot be removed by surgery and has worsened on prior treatment.

What's next?

The next hard date is earnings. Iovance reports third-quarter results on Thursday, November 5, 2026, and analysts expect about $115.5 million in sales, comprised entirely of Amtagvi. That report will test the commercial side of the story while the lung cancer question waits on more mature data — in particular, a duration-of-response number and results from a prospective biomarker-enriched cohort. Until those arrive, Thursday's verdict stands: a response rate that held up was not enough, on its own, to hold up the stock. This article reports what happened and why markets reacted; it is not a recommendation to buy, sell or hold any security.

Sources

FAQ

Why did Iovance stock fall 35% on October 29, 2026?

Investors sold after updated lifileucel lung cancer data matched the earlier response rate but gave no figure for how long responses last, leaving the therapy's main advantage unproven for now.

What was the response rate in the IOV-LUN-202 trial?

The objective response rate was 24.6% in 69 patients with previously treated non-squamous metastatic non-small cell lung cancer, versus 25.6% in an earlier 39-patient cut.

Is lifileucel already approved for anything?

Yes. Sold as Amtagvi, it is approved to treat melanoma that cannot be removed surgically and has worsened after previous treatment; lung cancer would be an expansion.

When does Iovance report earnings next?

Iovance is due to report third-quarter results on November 5, 2026, with analysts expecting about $115.5 million in sales, all from Amtagvi.