Association between gut microbiota characteristics and therapeutic efficacy of multimodal combination therapy in hepatocellular carcinoma with portal vein tumor thrombus: a secondary analysis of a prospective phase II trial.
Liang X, Li Y, et al. • Frontiers in immunology • 2026
In HCC patients with PVTT treated with SBRT plus cadonilimab and lenvatinib, overall gut microbiota architecture remained relatively stable, whereas selected baseline genus-level features—most notably Extibacter as a non-response-associated signal—were associated with therapeutic response.
Key Findings
Results
Baseline Faith's phylogenetic diversity was significantly higher in responders compared to non-responders, while other alpha-diversity indices were largely comparable between groups.
23 treatment-naïve HCC patients with PVTT were included; 10 were responders (CR/PR) and 13 were non-responders (SD/PD) by mRECIST criteria.
Faith's phylogenetic diversity was higher in responders (P = 0.0178).
Other alpha-diversity indices did not show statistically significant between-group differences at baseline.
46 paired fecal samples were collected: Phase A (before treatment) and Phase B (after 3 cycles of cadonilimab).
Results
Beta-diversity analysis did not reveal clear between-group separation at baseline or marked community restructuring after treatment.
Beta-diversity metrics were applied to both baseline (Phase A) and post-treatment (Phase B) samples.
No clear separation between responders and non-responders was observed at either timepoint.
The overall gut microbiota architecture was described as 'relatively stable' across the treatment period.
A total of 1,410,203 high-quality non-chimeric reads were retained and rarefied to 5,459 reads per sample for analysis.
Results
Genus-level DESeq2 analysis identified 7 differential genera at baseline between responders and non-responders.
Analysis was performed using 16S rRNA amplicon sequencing with downstream bioinformatic analyses including DESeq2 differential abundance testing.
Seven genera showed differential abundance at baseline between the two response groups.
Extibacter was absent in all responders but detectable in 6 of 13 non-responders.
Extibacter showed the strongest discriminatory signal among all identified differential genera (P = 0.0179).
Results
Extibacter demonstrated exploratory discriminatory performance as a non-response-associated biomarker, with AUC improving when combined with AFP.
In exploratory ROC analysis, baseline Extibacter alone yielded an AUC of 0.731.
When Extibacter was combined with AFP (alpha-fetoprotein), the AUC increased to 0.777.
Extibacter was absent in all 10 responders and present in 6/13 (approximately 46%) of non-responders.
Authors characterized this as an 'exploratory non-response-associated signal that requires validation in larger independent studies.'
Results
[Ruminococcus]_gnavus_group abundance was positively correlated with predicted KEGG functional modules for 'immune diseases' and 'carbohydrate metabolism' after correction for multiple comparisons.
Predicted functional analysis was performed using KEGG pathway profiles derived from 16S rRNA data.
[Ruminococcus]_gnavus_group showed positive correlation with both 'immune diseases' and 'carbohydrate metabolism' KEGG level 2 modules.
Differences in KEGG level 2 modules were observed between groups in the broader predicted functional analysis.
Methods
This study was a complementary exploratory analysis nested within a prospective phase II trial of SBRT combined with cadonilimab and lenvatinib for HCC with PVTT.
The parent trial is registered at ClinicalTrials.gov (identifier NCT06040177).
The study enrolled 23 patients from a prospective multicenter exploratory cohort drawn from the parent trial.
Patients were categorized by best mRECIST response: responders (CR/PR; n = 10) and non-responders (SD/PD; n = 13).
All patients were treatment-naïve at enrollment.
16S rRNA amplicon sequencing was used; the study assessed microbial diversity, differential taxa, predicted KEGG functional profiles, and exploratory discriminatory performance.
What This Means
This research examined whether the community of bacteria living in the gut (the gut microbiota) could help predict how well patients with an aggressive form of liver cancer (hepatocellular carcinoma with portal vein tumor thrombus) would respond to a combination treatment involving targeted radiation (SBRT), an immunotherapy drug (cadonilimab), and a targeted therapy drug (lenvatinib). Stool samples were collected from 23 patients before and after three cycles of treatment, and bacterial DNA was analyzed to characterize the gut microbial communities. Patients who responded to treatment (tumor shrinkage or disappearance) were compared to those who did not respond.
The study found that the overall composition of gut bacteria remained relatively stable throughout treatment. However, certain bacterial groups at baseline differed between responders and non-responders. Most notably, a genus called Extibacter was completely absent in all patients who responded to treatment but was detectable in nearly half of the non-responders. When used as a marker, Extibacter showed moderate ability to distinguish responders from non-responders, and this predictive ability improved slightly when combined with a standard blood marker for liver cancer (AFP). Additionally, patients who responded tended to have greater diversity in their gut bacteria, as measured by one specific diversity metric (Faith's phylogenetic diversity).
This research suggests that certain features of a patient's gut bacteria before starting treatment may be linked to how well they respond to this combination therapy for liver cancer. The finding around Extibacter is particularly notable as a potential early indicator of non-response. However, the authors themselves emphasize that this was a small exploratory study with only 23 patients, and these findings need to be confirmed in larger, independent studies before any clinical conclusions can be drawn.
Liang X, Li Y, Liang M, Zeng Z, Hu K, Yang L, et al.. (2026). Association between gut microbiota characteristics and therapeutic efficacy of multimodal combination therapy in hepatocellular carcinoma with portal vein tumor thrombus: a secondary analysis of a prospective phase II trial.. Frontiers in immunology. https://doi.org/10.3389/fimmu.2026.1864941