Moderna Stock Slides Again Friday: What's Going On?

Moderna Inc. (NASDAQ:MRNA) stock extended its decline in Friday’s premarket trading after plunging more than 17% Thursday amid investor concerns over clinical trial data for its experimental personalized melanoma vaccine.

The selloff followed an alleged leak of an abstract from the ESMO 2026 conference, raising questions about the vaccine’s effectiveness.

Later Thursday, Moderna and Merck & Co. Inc. (NYSE:MRK) released detailed results from the Phase 3 INTerpath-001 trial.

The study evaluated intismeran combined with Merck’s Keytruda (pembrolizumab) against Keytruda alone in patients with stage IIB-IV melanoma who had undergone surgery.

Combination Therapy Cuts Cancer Recurrence Risk

In the trial’s primary analysis, intismeran plus Keytruda reduced the risk of cancer recurrence or death by 42% after a median follow-up of 24.6 months.

The combination also lowered the risk of distant metastasis or death by 38% compared with Keytruda alone.

Researchers reported consistent improvements in recurrence-free survival and distant metastasis-free survival across prespecified patient subgroups.

Vaccine Shows Stronger Benefits After Six Months

The combination therapy showed greater benefits after patients completed their initial immunization series.

During the first six months, outcomes were similar between the treatment groups. However, a prespecified sensitivity analysis showed that the combination reduced the risk of recurrence or death by 58% after that period.

It also cut the risk of distant metastasis or death by 50%.

A separate sensitivity analysis excluded patients who had not received at least one planned dose.

In that group, the combination reduced the risk of recurrence or death by 49% and distant metastasis or death by 45%.

William Blair Sees Sell-The-News Reaction

William Blair analyst Myles Minter suggested Thursday’s sharp selloff reflected profit-taking despite encouraging trial results.

“We had believed investors were looking for an HR of 0.6 or better on RFS, which was delivered according to the leaked information, but there appears to be a sell-the-news reaction playing out here,” the analyst wrote.

The firm noted that Moderna shares had surged 525% year to date, even after Thursday’s decline.

Minter also said the data suggested similar effectiveness across patients with lower- and higher-risk disease, potentially signaling benefits across different levels of tumor mutational burden.

While calling the interim INTerpath-001 results encouraging, Minter cautioned that investors would continue to debate Moderna’s valuation and the vaccine’s potential across different tumor types.

MRNA Price Action

MRNA Price Action: Moderna shares were down 4.04% at $194.45 during premarket trading on Friday, according to Benzinga Pro data.

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