When a lock stops working, you can change the key - or bring a very small locksmith carrying chemotherapy.
That is roughly the idea behind ORCHARD, a phase II study testing osimertinib plus datopotamab deruxtecan in people with advanced EGFR-mutated non-small-cell lung cancer whose cancer had already grown on first-line osimertinib.
Cancer, naturally, did not file a complaint first. It just adapted.
The Usual Trick: EGFR Lung Cancer Learns to Dodge
Some lung cancers are powered by a mutation in EGFR, a growth-signal switch on the cell surface. When that switch gets stuck in the “go” position, cells can divide like someone taped down the accelerator.
Osimertinib targets that switch. For many patients, it works remarkably well. It can shrink tumors, slow progression, and often reach brain metastases better than older EGFR drugs.
Then resistance shows up.
This is the part where cancer biology becomes less “one villain, one weapon” and more “the villain hired consultants.” Tumors may mutate EGFR again, amplify MET, activate bypass pathways, transform their cell identity, or do something we still cannot neatly name. Reviews of osimertinib resistance describe a messy landscape where many patients have no single obvious target after progression Fu et al., 2022; Lee et al., 2022.
That is the problem ORCHARD is trying to solve.
Enter the Smart Bomb, With Paperwork
Datopotamab deruxtecan, or Dato-DXd, is an antibody-drug conjugate. That means it has three parts: an antibody, a linker, and a chemotherapy payload.
The antibody targets TROP2, a surface protein found on many epithelial cancers, including lung cancers. Once Dato-DXd binds, the cancer cell internalizes it, the linker gets cut, and the payload gets released.
Elegant. Also slightly rude, if you are a cancer cell.
Dato-DXd already has evidence as a single agent in previously treated NSCLC, including tumors with actionable genomic alterations such as EGFR mutations. In TROPION-Lung05, it showed activity after targeted therapy and platinum chemotherapy Ahn et al., 2025. In TROPION-Lung01, it beat docetaxel on progression-free survival in previously treated advanced NSCLC, with the clearest signal in nonsquamous disease Ahn et al., 2024.
The ORCHARD twist: instead of using Dato-DXd alone, researchers kept osimertinib on board and added Dato-DXd after progression.
Why keep the old drug when the cancer has progressed? Because not every tumor cell may be resistant in the same way. Some cells may still depend on EGFR signaling. Cancer is rarely tidy. It does not alphabetize its escape routes.
What ORCHARD Found
The study enrolled 69 patients with EGFR-mutated advanced NSCLC after progression on first-line osimertinib. Patients received osimertinib 80 mg daily plus Dato-DXd every three weeks at either 4 mg/kg or 6 mg/kg.
The response rates were notable:
- 43% confirmed objective response rate with 4 mg/kg
- 36% confirmed objective response rate with 6 mg/kg
Median progression-free survival was:
- 9.5 months with 4 mg/kg
- 11.7 months with 6 mg/kg
Duration of response looked longer in the 6 mg/kg group: 20.5 months, though with wide uncertainty. Overall survival was also numerically longer at 6 mg/kg: 26.2 months, compared with 19.8 months at 4 mg/kg.
Small study. Open-label. No randomized control arm. Still, those numbers are hard to ignore. They do not shout. They clear their throat very firmly.
The Price Tag: Toxicity
The 6 mg/kg dose looked stronger, but it also hit harder.
Grade 3 or higher adverse events occurred in:
- 49% of patients at 4 mg/kg
- 76% at 6 mg/kg
Dose reductions were much more common at 6 mg/kg. Interstitial lung disease or pneumonitis, a serious lung inflammation risk, occurred in 3% at 4 mg/kg and 15% at 6 mg/kg.
That matters. These are patients with lung cancer. Their lungs already have enough plot.
The authors argue that 6 mg/kg has the better overall benefit-risk profile when used with monitoring, prevention strategies, and dose reduction. That is reasonable, but it also means this combination is not a casual add-on. It needs careful eyes.
Why This Matters
After first-line osimertinib stops working, the next step can be frustrating. If testing finds a clear resistance mechanism, doctors may match a targeted therapy. If not, patients often move toward chemotherapy-based options.
ORCHARD points to a broader strategy: keep suppressing EGFR while adding an antibody-drug conjugate that can attack tumor cells through TROP2. It is less like finding the one master switch and more like cutting power while also changing the locks.
If larger randomized trials confirm these results, this could help patients whose cancers have outgrown osimertinib but still carry EGFR-mutated biology. It may also fit into the growing ADC era, where lung cancer treatment becomes less about plain chemotherapy and more about delivery systems with bad news attached.
Not magic. Not done. But interesting medicine.
And in oncology, interesting medicine that buys time with a tolerable plan is not a small thing.
References
Riess JW, Yu HA, Le X, et al. Osimertinib plus datopotamab deruxtecan in patients with EGFR-mutated advanced NSCLC after progression on first-line osimertinib: ORCHARD. Annals of Oncology. 2026. https://doi.org/10.1016/j.annonc.2026.02.014
Fu K, Xie F, Wang F, Fu L. Therapeutic strategies for EGFR-mutated non-small cell lung cancer patients with osimertinib resistance. Journal of Hematology & Oncology. 2022;15:173. https://doi.org/10.1186/s13045-022-01391-4
Lee J, Piotrowska Z, Soo R, Cho BC, Lim SM. Combatting acquired resistance to osimertinib in EGFR-mutant lung cancer. Therapeutic Advances in Medical Oncology. 2022;14. https://doi.org/10.1177/17588359221144099
Ahn MJ, et al. Datopotamab deruxtecan in advanced or metastatic non-small cell lung cancer with actionable genomic alterations: results from the phase II TROPION-Lung05 study. Journal of Clinical Oncology. 2025;43:1254-1265. https://doi.org/10.1200/JCO-24-01349
Ahn MJ, et al. Datopotamab deruxtecan versus docetaxel for previously treated advanced or metastatic non-small cell lung cancer: the randomized, open-label phase III TROPION-Lung01 study. Journal of Clinical Oncology. 2024. https://doi.org/10.1200/JCO-24-01544
Disclaimer: The image accompanying this article is for illustrative purposes only and does not depict actual experimental results, data, or biological mechanisms.