Moderna Stock Selloff: Why positive cancer vaccine results failed to lift shares

Moderna shares plunged sharply on October 22 after detailed late-stage trial results for its experimental personalised melanoma vaccine failed to sustain investor enthusiasm. The selloff erased about $24 billion in market value, despite encouraging clinical findings. The decline followed a spectacular rally that had lifted the stock by more than 500% this year. (Sources: Reuters, TradingKey, Yahoo Finance)

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​Cancer Vaccine Cuts Recurrence Risk by 42%

Moderna and Merck's Phase III INTerpath-001 trial evaluated intismeran autogene alongside Keytruda in more than 1,100 patients with high-risk melanoma. The combination reduced the risk of cancer recurrence or death by 42% and the risk of distant metastasis or death by 38%, compared with Keytruda alone.

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​Two-Year Results Show Promise

Approximately 82.2% of patients receiving the vaccine combination remained free of melanoma recurrence at two years, compared with 70% of patients receiving Keytruda alone. The findings mark a significant development for personalised mRNA cancer treatments. However, overall survival data remain immature and require further follow-up.

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​Why Investors Sold Despite Positive Results

Investors had already priced in substantial optimism after Moderna's rally earlier this year. The detailed results prompted a sell-the-news reaction, while questions remained over the treatment's commercial potential and its effectiveness beyond melanoma. Analysts also scrutinised the results against expectations raised by earlier trial findings.

ETiStock

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​$176–$180 Support Zone in Focus

Moderna shares fell below key short-term moving averages, signalling increased selling pressure. TradingKey identified the $176–$180 range as an important support zone, with $160 as a possible downside level if support breaks. A recovery could bring the stock towards the $250 resistance area, although these are technical levels rather than guaranteed price targets.

ETMarkets.com

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​Regulatory Timeline and Future Cancer Trials

Moderna and Merck are engaging with regulators, with a potential US regulatory submission aimed at supporting a 2027 launch timeline. The treatment's longer-term commercial opportunity will depend on regulatory decisions, additional survival data and results from trials in other cancers, including lung, kidney and bladder cancer. For investors, the key question is whether the promising melanoma results can translate into a broader oncology business.