The antibody-drug conjugate HER3-DXd, when combined with the PARP inhibitor olaparib, demonstrates significantly stronger anti-tumor effects in lung cancer models than either treatment used alone. This combination mechanism forces cancer cells to accumulate irreparable DNA damage while simultaneously stimulating the immune system to target tumors more aggressively.
Lung cancer holds the grim distinction of being both the most frequently diagnosed cancer worldwide and the leading cause of cancer-related deaths. Although smoking rates have declined among men, incidence rates are climbing among younger women who do not smoke. Many existing targeted therapies eventually fail as tumors develop resistance mechanisms.
Researchers from Tampere University, the University of Helsinki, Harvard University, and the Dana-Farber Cancer Institute investigated the combination therapy in non-small cell lung cancer models, which is the most common form of lung cancer. Their focus centered on tumors carrying EGFR or KRAS mutations. The study revealed that olaparib disrupts DNA repair pathways in cancer cells, while HER3-DXd delivers a cytotoxic agent specifically to cells expressing the HER3 protein—a marker present in most non-small cell lung cancers.
The results showed that the combination therapy overwhelmed cancer cells’ ability to repair damage, triggering massive programmed cell death. Tumor progression slowed dramatically, and treated lab animals exhibited extended survival. These benefits were observed consistently across both EGFR-mutated and KRAS-mutated tumor models.
The therapy’s effectiveness extended beyond direct cell destruction. Activation of the cGAS-STING immune pathway enhanced the body’s natural defenses, making natural killer cells more potent against cancer cells. This dual mechanism, targeted cell killing combined with immune system activation, created a more robust anti-tumor response.
Unlike many precision cancer drugs, this combination demonstrated broad activity against genetically diverse lung cancers. Heidi Haikala, the lead investigator from Tampere University and Assistant Professor at the University of Helsinki, highlighted that HER3 expression could serve as a predictive biomarker to select patients most likely to respond. Given that HER3 is also frequently found in other solid tumors, the approach may hold promise for treating cancers beyond lung malignancies.
These findings provide a strong foundation for advancing the combination into human clinical trials. The research was published under the title PARP inhibition enhances the antitumor activity of HER3-DXd in non-small cell lung cancer.
