Full-Life's c-MET tracer FL-261 shows high lesion contrast in first NSCLC patients

Imaging results from 10 lung cancer patients

The data were presented as a Top Rated Oral Presentation (OP-442) at the 39th Annual Congress of the European Association of Nuclear Medicine (EANM) in Vienna, held October 17 to 21, 2026. Full-Life Technologies, a privately held, clinical-stage radiopharmaceutical company, describes FL-261 as a c-MET-targeted theranostic radionuclide drug conjugate (RDC), meaning one ligand can be used for both imaging and treatment.

The prospective clinical trial enrolled 10 patients with histologically confirmed NSCLC and was designed to evaluate safety, biodistribution and diagnostic performance. Patients underwent SPECT/CT imaging 4, 24 and 72 hours after injection, plus a baseline [18F]FDG PET/CT for comparison. Mean age was 65.3 years (range 59 to 71), and nine of 10 patients were male. Five patients had adenocarcinoma, four had squamous cell carcinoma and one had NSCLC not otherwise specified. One patient had MET exon 14 skipping, two had no MET alteration detected and seven were not tested.

Uptake tracks c-MET expression

For a patient with a high c-MET immunohistochemistry (IHC) score, tumor SUVmax was 13.8, 25.7 and 43.2 at 4, 24 and 72 hours. For a patient with a moderate IHC score, the values were 12.7, 22.9 and 20.7. The ratio of tumor SUVmax to kidney and bone marrow SUVmean ranged from 2.8 to 20.3 and from 17.4 to 72.4 respectively for these two patients at all time points.

Across six patients with available c-MET IHC scores, uptake of [111In]In-FL-261 in lesions showed a positive trend with c-MET expression (Spearman rho 0.82, P = 0.034). [18F]FDG uptake did not (rho -0.13, P = 0.80).

Tracer uptake in normal organs was generally low with rapid washout, according to the company. The organs with the highest uptake were liver, spleen and kidneys. [111In]In-FL-261 was well tolerated in all patients, with no tracer-related serious adverse events.

Prof. Xiaoli Lan of Union Hospital, Tongji Medical College, said that c-MET is "an oncogenic driver and a mediator of resistance to treatment in lung cancer". He called the ability to see c-MET expression across the whole body noninvasively "an encouraging step toward matching radioligand therapy to the patients who can benefit."

Preclinical data and the path to Phase 1

Full-Life also presented E-Poster #0035, which covers discovery and preclinical work on FL-261. In cells and tumor-bearing mice, [111In]In-FL-261 showed potent, c-MET-specific binding and rapid internalization. Tumor uptake exceeded that of normal organs and was nearly completely blocked by unlabeled FL-261. The actinium-225 version, [225Ac]Ac-FL-261, produced marked tumor regression in xenograft models with varying levels of c-MET expression. These included a model derived from a patient previously treated with a c-MET-targeted antibody-drug conjugate, with no notable changes in body weight.

In September 2026, the company announced that the U.S. Food and Drug Administration had cleared the Investigational New Drug application for [225Ac]Ac-FL-261, and that clearances had also been received in Australia and China. These allow the Phase 1 SumMET trial (NCT07873450) to proceed at sites in those countries for patients with non-squamous NSCLC that expresses c-MET.

What it means

The imaging study is small, with 10 patients, and the correlation with c-MET expression rests on six patients with IHC scores. Even so, Chief Medical Officer Debora Barton said the data "provide strong support to advance [225Ac]Ac-FL-261 into the SumMET Phase 1 trial." If the approach holds up in larger groups, a c-MET imaging agent could help identify which patients are suited to the matching alpha-emitting therapy.

Full-Life lists three clinical-stage programs, including [225Ac]Ac-FL-020 for metastatic castration-resistant prostate cancer and an NTSR1-targeted small-molecule radioconjugate. FL-261 is its c-MET-targeted candidate, with an initial focus on non-squamous NSCLC.