Moderna’s Cancer Vaccine Rally Hits a Wall. This Other Drugmaker Stole the Show.

Moderna and Merck were set to present an expanded data set for their experimental cancer vaccine, intismeran autogene, at an oncology conference; however, the results were leaked. (Maddie Meyer/Getty Images)

Key Points

Moderna and Merck presented late-stage trial data for their cancer vaccine candidate, intismeran, at a European medical conference.
Citi analyst Geoff Meacham noted that the intismeran presentation drew a lukewarm reception and far less enthusiasm than Amgen’s presentation.
Amgen reported that its experimental treatment Imdelltra combined with AstraZeneca’s Imfinzi reduced the risk of death by 58% in a trial.

Moderna and Merck were primed for a victory lap at Europe’s premier oncology conference, but it was another drugmaker that stole the show.

In August, the partners previewed late-stage trial data for their cancer vaccine candidate, intismeran autogene, which sparked a massive run-up in Moderna shares. That momentum made the annual meeting of the European Society for Medical Oncology (ESMO), which kicked off Oct. 23, a high-stakes proving ground for the drug.

However, a data leak days earlier blunted the impact. While the findings were solid, they fell short of the lofty expectations priced in following the stock’s eye-watering rally in late summer.

Citi analyst Geoff Meacham noted that while the presentation reinforced intismeran’s “meaningful efficacy in melanoma,” attendee reception was lukewarm at best—drawing a “minimal standing ovation” and far less enthusiasm compared with Amgen’s presentation for its experimental small-cell lung cancer drug.

“While audience reaction is not a clinical endpoint, we think it reflected a dataset…that supports approval but leaves intismeran’s positioning unresolved,” Meacham wrote in a research note after the event.

Intismeran was hailed as a paradigm shift in cancer treatment when partial data showed that combining the vaccine with Merck’s blockbuster immunotherapy Keytruda reduced the risk of melanoma recurrence more effectively than Keytruda alone.

Following ESMO, however, intismeran’s prospects are even less certain. Concerns beyond the trial data itself are coming back into focus, such as manufacturing hurdles and competition from cheaper, off-the-shelf neoadjuvant immunotherapies.

A recurring question is whether the findings offer any read-through to intismeran’s efficacy in other tumor types. While analysts had already cautioned in August that broad applicability was a long shot, especially as other trials run their course, the data appear to have tempered optimism for now. As Meacham noted, “the presentation did not validate a transformative oncology modality.”

While the intismeran data missed investors’ elevated expectations, another drugmaker delivered the spark investors were looking for.

Over the weekend, Amgen showcased late-stage trial data for its experimental treatment Imdelltra in combination with AstraZeneca’s Imfinzi for patients with extensive-stage small-cell lung cancer.

The combined treatment reduced the risk of death by 58%, Amgen reported, calling the figure “unprecedented.”

Wall Street was equally impressed. Jefferies analyst Akash Tewari described the data as “excellent” and noted that the presentation received an enthusiastic standing ovation.

Amgen shares advanced 0.3% on Monday as Moderna fell 1.3%, extending losses for a third straight trading session. Merck, meanwhile, fell 2.4%.

The results were particularly impactful given that patients with this specific cancer have historically faced very poor survival rates. Standard chemotherapy combined with immunotherapy typically keeps the disease from progressing for only about 5 months, with overall survival averaging just 12 to 13 months.

The combination of Imdelltra and Imfinzi worked so well, Tewari added, that he expects it to become the standard of care for maintenance therapy, an approach designed to keep the cancer from returning after it responds to initial treatment. He models $5 billion in peak annual sales for Imdelltra, up sharply from the $627 million it generated last year.

A big piece of the equation is limited commercial competition. While both drugs are already on the market, they aren’t prescribed together as standard of care, and currently approved alternatives have little to offer.

Tewari cited a combination of lurbinectedin and atezolizumab approved for extensive-stage small-cell lung cancer in late 2025, saying it provides “only incremental benefit” in a maintenance setting.

Other voices on the Street are just as constructive on the drug’s commercial trajectory. William Blair analyst Matt Phipps noted that Amgen plans to quickly submit the data to regulators to support Imdelltra’s label expansion.

Phipps is eyeing a “significant market opportunity” for the drug, which was already on pace for more than $1 billion in annualized sales through the first half of 2026. The results augment a recent string of positive clinical readouts and further diversify Amgen’s commercial portfolio, he added.

Caution is still warranted, especially taking Moderna’s historic rally as precedent. Amgen’s valuation relies on far more than this single asset, and questions remain around its execution in weight-loss with MariTide.

Regardless, the massive survival benefit establishes Imdelltra as one of the conference’s standouts—and underlines just how quickly Moderna’s fortunes have turned.

Write to Mackenzie Tatananni at mackenzie.tatananni@barrons.com

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