A first-in-human study of an experimental immunotherapy has produced an encouraging—but still preliminary—signal in people with advanced solid tumors that had stopped responding to standard treatments. The investigational drug, invikafusp alfa (invika), is designed to stimulate a narrow set of tumor-fighting T cells rather than activating the immune system broadly.
What was tested
The phase 1 and early phase 2 START-001 trial enrolled people with several types of advanced solid cancer, most of whom had already received immune checkpoint inhibitors without durable benefit. During phase 1, researchers tested different doses every two weeks to assess safety and identify a dose that produced the intended immune response. Participants in the early phase 2 portion then received that selected dose.
Invika is a bispecific protein intended to engage two groups of tumor-infiltrating T cells. The rationale is precision: expanding immune cells already positioned to recognize tumor tissue may strengthen anti-tumor activity while avoiding the widespread immune activation associated with some other T-cell approaches.
The early results
Among 27 participants treated at the selected dose across the two phases, 16—59.3%—had no disease progression during the assessment period. Four participants, or 14.8%, had reductions of more than 30% in the size of targeted tumors. Responses included people with treatment-resistant metastatic colorectal cancer and advanced non-small cell lung cancer.
These numbers should be read in context. This was a small, early-stage trial involving different tumor types and no randomized comparison group. “Disease control” combines stable disease and tumor shrinkage; it does not show that the treatment improves survival. Participants also received the drug after extensive prior treatment, so the results cannot be generalized to people with earlier-stage cancer.
Safety and mechanism
Several participants experienced flu-like effects, which the investigators described as expected and generally manageable with supportive care. At the selected dose, the drug expanded the targeted T-cell populations without broadly affecting other T cells. The largest changes in those target populations occurred in the four participants whose tumors shrank, although immune changes did not always translate into a measurable clinical response.
That distinction matters. A treatment can produce the biological effect it was designed to create without necessarily delivering a lasting benefit for every patient. Larger studies must establish how long tumor control persists, which cancers are most likely to respond, and whether combinations with other therapies improve outcomes.
What happens next
The trial remains ongoing. Further research will need to confirm the selected dose, monitor uncommon or delayed adverse effects, and compare outcomes with established treatment strategies. Biomarker work may also clarify which patients have tumors containing the T-cell populations that invika is designed to stimulate.
For now, invika should be understood as an experimental treatment—not an approved alternative to standard cancer care. The study provides a reason for continued investigation in a difficult clinical setting, but it does not support changing treatment outside a clinical trial. Patients considering research participation should discuss eligibility, potential benefits, uncertainties and alternatives with their oncology team.
Source: U.S. National Institutes of Health, reporting the phase 1/2 START-001 trial published in Nature Medicine on 23 October 2026.
Image: National Cancer Institute via Unsplash, used under the Unsplash License.
