Bladder cancer drug alpha1-oleate disrupts adipokine-driven tumor metabolism

A bladder cancer therapy built from a fragment of human alpha-lactalbumin and oleic acid has been shown to act on more than tumor cell survival: it also reaches deep into the metabolic machinery of the tumor itself. In a secondary analysis of samples from a placebo-controlled Phase I/II trial, researchers report that intravesical treatment with the alpha1-oleate complex strongly suppressed metabolic genes and networks in non-muscle invasive bladder cancer tissue, with the adipokine regulators adiponectin and leptin emerging as central nodes of the response. The findings, published in Cancer & Metabolism, suggest that a locally delivered tumoricidal compound can simultaneously rewire how tumor tissue handles glucose and lipids.

The study drew on patients with non-muscle invasive bladder cancer (NMIBC) enrolled in a single-center, double-blinded, placebo-controlled Phase I/II clinical trial (EudraCT 2016-004269-14; NCT03560479). Participants received six intravesical instillations of alpha1-oleate at 8.5 mM (14 tumors) or placebo (27 tumors) over one month before transurethral resection of the bladder tumor (TURBT), and all completed treatment. Cells shed into the urine were harvested at each instillation, biopsies were taken at TURBT after the sixth instillation, and the material was subjected to RNA sequencing, genome-wide transcriptomic analysis and urine adipokine arrays.

In tissue biopsies, RNA sequencing detected significant inhibition of metabolic genes and networks in the alpha1-oleate group compared with placebo. Using a cutoff of fold change greater than 2 and P less than 0.05, the significantly regulated metabolic genes were predicted to affect glucose metabolism (261 genes), lipid metabolism (164 genes) or both (195 genes). The response was overwhelmingly suppressive: 517 of 678 significantly regulated metabolism-associated genes — 76 percent — were inhibited in treated tumors. Functional analysis pointed the same direction, with glucose metabolism disorder the most strongly affected function (341 of 455 downregulated genes), impaired glucose tolerance predicted, and glucose uptake, synthesis and carbohydrate metabolism inhibited. On the lipid side, lipid synthesis (99 of 118 downregulated genes), fatty acid metabolism, fatty acid concentration, terpenoid synthesis and steroid synthesis were all inhibited.

The most dramatic changes clustered around specific metabolic genes. The top ten regulated metabolic genes were downregulated with fold changes ranging from −78 to −26,907 relative to placebo. Among them were GC, encoding the vitamin D binding protein (FC = −26,907); ADIPOQ, which encodes the glucose- and lipid-regulating protein adiponectin (FC = −5,354); CALB1, encoding calbindin 1, a regulator of calcium and energy metabolism (FC = −429); BAAT (FC = −273); and CSF3 (FC = −171). Further down the list were EREG, encoding the growth factor epiregulin linked to metabolic reprogramming (FC = −127); the inflammatory chemokine CXCL2 (FC = −112); PTN, encoding pleiotrophin (FC = −96); DGKB (FC = −91); and the lipid droplet protein CIDEC (FC = −79). Networks built around these genes were similarly skewed toward suppression, with 66 of 78 genes downregulated in the ADIPOQ network, 15 of 19 in the GC network, 10 of 11 in the CALB1 network and 53 of 62 in the CSF3 network.

Leptin added a second regulatory axis. The gene encoding leptin, LEP, was strongly downregulated in treated tumor biopsies (FC = −60) and was identified as the top upstream regulator of ADIPOQ, with additional upstream regulators including PTGS2, CD36 and pro-inflammatory cytokines such as CRH, CXCL8, CCL11, IL1B, CCL2 and EDN1. Of the significantly regulated LEP-dependent genes, 55 of 70 were downregulated, and network analysis predicted inhibition of the CD36 receptor (FC = −7.6), lipoprotein lipase (FC = −4.3), perilipin 1 (FC = −6.9), acyl-CoA dehydrogenase long chain (FC = −2.7) and acetyl-CoA acetyltransferase 1 (FC = −2.1), consistent with broad effects on fatty acid uptake, storage and synthesis. The LEP and ADIPOQ networks were strongly interconnected, sharing regulated genes including FABP4 (FC = −3.9), FASN (FC = 2.98), LPL (FC = −4.34) and CD36 (FC = −7.6), along with PPARGC1A (FC = −5), PRKAA2 (FC = −3.4) and IGF1 (FC = −3). Interestingly, a set of upregulated genes encoding putative repressors — including FOXA2, PTH2R, IGHM, CXCR5, HTR3A, UTS2R, MMP8, GRIK3, CD79A and SLC27A2, with fold changes of roughly 13 to 24 — regulated networks of inhibited metabolic genes, hinting that activation of repressors may contribute to the overall inhibitory effect.

The treatment effect was not uniform across the bladder. Because bladder cancer is known to have a field effect, in which apparently healthy tissue may still harbor malignant or precancerous cells, the researchers compared treated tumor biopsies with biopsies from macroscopically benign areas located away from the tumor. Principal component analysis showed that samples from alpha1-oleate-treated patients clustered apart from the placebo group in both tissue types, but the benign-tissue samples clustered closer to the treated tumors than to placebo, suggesting a treatment effect that was weaker than in tumor tissue. In the direct comparison, about 1,200 genes were significantly regulated only in the tumor group, and 1,050 of them — 87 percent — were inhibited. ADIPOQ-dependent (118 of 130 genes) and LEP-dependent (155 of 180 genes) networks were again suppressed, indicating that the compound acts most potently where malignant cells are concentrated.

Urine samples provided a window on how fast the metabolic response unfolds. RNA isolated from cells shed into the urine within two hours of instillation showed a striking shift compared with pre-treatment samples: 1,145 of 1,192 regulated metabolic genes — 96 percent — were inhibited, using a high cutoff of fold change at least 5 and P less than 0.05. The top downregulated gene, SAT1, is a known bladder cancer biomarker that regulates polyamine synthesis and positively regulates insulin sensitivity and lipid peroxidation. Functional analysis identified inhibited glycolysis, glucose uptake and metabolism, lipid metabolism and prostaglandin synthesis. Adiponectin and leptin were not among the top regulated genes in urine RNA, but their networks showed a predominance of inhibition, including the adiponectin receptor R1, and the magnesium homeostasis gene SLC41A was the top upregulated metabolic gene. The authors interpret these findings as evidence of rapid kinetics in the metabolic response of treated tumor cells.

Protein-level measurements reinforced the transcriptomic picture. Using a customized Luminex panel of 16 human adipokines, the team quantified urinary adipokine levels in six patients per group across six visits. No changes were detected in the placebo group, indicating that the instillation procedure itself did not alter urinary adipokine concentrations. In the alpha1-oleate group, post-instillation urine showed increased levels of adiponectin, leptin, vitamin D binding protein, TIMP-1, PBEF/visfatin and cathepsin S, assessed with the Mann Whitney U-test, while insulin, TREM-1, IGFBP-rp1/IGFBP-7, CXCL2, myeloperoxidase, DPPIV/CD26 and M-CSF remained unchanged and resistin was lower than in placebo. The response was rapid for several adipokines and, for adiponectin, leptin, vitamin D binding protein and TIMP-1, was maintained relative to pre-instillation samples, suggesting both acute and sustained effects.

Immunostaining of shed cells traced the adipokine signal back to the tumor cells themselves. Alpha1-oleate is known to trigger rapid tumor cell detachment within two hours of instillation, raising cell counts in urine to several hundred thousand or millions per milliliter. In matched pre- and post-treatment samples from a subset of patients at visits 3 and 6, cytospin preparations of shed cells and tissue fragments showed higher cellular adiponectin levels after treatment than before, and the staining intensity was higher in post-treatment samples from treated patients than in the placebo group, albeit with heterogeneity. Leptin staining was detected in three alpha1-oleate-treated patients and one placebo patient. Notably, lower urine RNA levels for adiponectin and leptin gene networks were found in the same samples where shed cells contained high adiponectin protein, and neither pre-treatment samples nor placebo samples showed increased protein levels, indicating that both endpoints were treatment-related. The authors propose that shedding of cells rich in adiponectin and leptin could potentially deplete the tumor of cells with high adipokine levels.

The study has limits worth noting. It is a secondary analysis of a Phase I/II trial rather than a trial designed around metabolic endpoints, the adipokine comparison involved six patients per group, and the IPA-based functional predictions of glucose and lipid effects are computational inferences from gene expression, not direct measurements of metabolic flux. The molecular mechanism by which alpha1-oleate regulates ADIPOQ and LEP expression was not addressed experimentally here, although the authors cite recent in silico modeling with AlphaFold 3 and surface plasmon resonance data suggesting the complex may bind the adiponectin receptor AdipoR2, with preliminary evidence for interaction with the leptin receptor. Even with those caveats, the convergence of transcriptomic suppression, rapid urine RNA changes, altered urinary adipokine proteins and stained shed cells makes a coherent case: in these patients, alpha1-oleate acted as a broad local inhibitor of tumor metabolism, targeting the adiponectin–leptin axis that earlier work has linked to bladder cancer recurrence, progression and signaling through JAK/STAT, PI3K/Akt/mTOR, MAPK/ERK and RAS pathways. Whether this ‘inverse metabolic reprogramming’ translates into improved clinical outcomes will require further study, but the results mark adipokine-dependent metabolism as a tangible, druggable dimension of the HAMLET-family complex’s anti-tumor activity.

Subject of Research: Effects of intravesical alpha1-oleate on adipokine-dependent metabolism in non-muscle invasive bladder cancer

Article Title: Identification of alpha1-oleate as a potent regulator of adipokine-dependent metabolism, in bladder cancer tissue

Article References: Haq, F., Chinchankar, S., Ambite, I., Ahmadi, S., Tran, H., Nazari, A., Brisuda, A., Hacek, J., Babjuk, M., & Svanborg, C. (2026). Identification of alpha1-oleate as a potent regulator of adipokine-dependent metabolism, in bladder cancer tissue. Cancer & Metabolism, 14(1), Article 21. https://doi.org/10.1186/s40170-026-00445-2

Image Credits: AI Generated

DOI: 10.1186/s40170-026-00445-2

Keywords: bladder cancer, alpha1-oleate, adiponectin, leptin, tumor metabolism, intravesical therapy, transcriptomics, NMIBC, adipokines, HAMLET, clinical trial, urine biomarkers