ALDH1L2 Reduces Sunitinib Sensitivity in Renal Cancer Organoids
Three renal cancer organoid models linked ALDH1L2 to redox changes and reduced sunitinib response. A candidate compound, HA-1, bound ALDH1L2 and strengthened the organoid response to sunitinib, while its mechanism, exposure and safety remain unresolved.
Starting with Organoids from Poor Clinical Responders
Researchers at the Second Affiliated Hospital of Hainan Medical University and collaborating academic centers studied a metabolic component of sunitinib response in renal cell carcinoma. Their Biology Direct paper used three patient-derived organoid lines from patients with poor response or resistance to sunitinib, alongside cell-line and xenograft experiments. The work identified ALDH1L2 as a contributor to reduced drug sensitivity under the tested conditions.
The organoids received sunitinib for 48 hours across a concentration series from 0.1 to 1,000 μM, with untreated controls. Their estimated IC50 values were around 8 μM, and subsequent experiments used 10 μM for 48 hours. ATP-based viability, live/dead staining and redox measurements supplied different views of the response. Five paired clinical tumor and peritumor specimens were used separately to examine ALDH1L2 expression.
ALDH1L2 Perturbation Shifted the Drug Response
RNA sequencing after sunitinib exposure identified 236 differentially expressed genes: 80 increased and 156 decreased. ALDH1L2 was among the increased genes. Increasing its expression reduced sunitinib-associated growth injury and reactive oxygen species, whereas reducing expression shifted responses in the opposite direction.
The accompanying measurements included GPX4 and SLC7A11, glutathione and NADPH-related redox balance, ferrous iron and malondialdehyde. The pattern supported a link to ferroptosis-associated responses, and erastin counteracted the protective effect of ALDH1L2 overexpression. The study did not establish death specificity through ferroptosis-inhibitor rescue or a direct lipid-reactive-oxygen assay, so the redox findings provide a narrower mechanistic conclusion than a complete demonstration of one death pathway.
An organoid-derived xenograft experiment used 24 mice, six per group. ALDH1L2 overexpression reduced the tumor-growth suppression and oxidative response associated with sunitinib. This added an in vivo comparison of ALDH1L2 status; it did not test the candidate combination subsequently studied in culture.
A Binding Candidate Emerged from a Natural-Product Screen
The team docked 310 natural-product monomers against ALDH1L2, narrowed the candidates computationally and tested six compounds in 786-O renal cancer cells. HA-1 had the lowest cellular IC50 among these candidates and was taken forward. It reduced ALDH1L2 abundance and produced a thermal-stability change in a cellular target-engagement assay.
Surface plasmon resonance measured direct binding with an estimated dissociation constant of 7.83 × 10⁻⁶ M. Binding and reduced protein abundance support an interaction with ALDH1L2, although the paper did not establish inhibition of its catalytic activity with a dedicated enzyme assay. The mechanism by which HA-1 lowers protein abundance also remains to be resolved.
Combination Activity Remains a Preclinical Finding
HA-1 plus sunitinib produced stronger growth and viability effects than the individual conditions, accompanied by greater oxidative and ferroptosis-associated changes. The combination also counteracted protection associated with ALDH1L2 overexpression. These results support further investigation of the target–drug relationship in the experimental models.
The public expression analysis addressed a different question. An ROC AUC of 0.695 distinguished renal cancer from normal tissue in TCGA-KIRC; the dataset lacked the sunitinib-response information needed to evaluate a resistance predictor. It therefore does not establish ALDH1L2 expression as a patient-selection biomarker for this drug.
The organoid evidence comes from three donors, and the HA-1 combination was not supported by in vivo pharmacokinetic, toxicity or efficacy testing in this paper. Larger donor collections, clearer death-pathway tests and exposure measurements would be needed to determine whether the combination retains its activity at tolerable concentrations.