The story of SLU-PP-915 is not a story about a new fat-burning mechanism. Its mechanism is the same as its predecessor's: activation of the estrogen-related receptors ERRα/β/γ. It is a story about good pharmacology that could not reach the body, and what chemists did to fix that.
The molecule that did not survive the liver
A few years ago Thomas Burris's laboratory at Saint Louis University described SLU-PP-332, a small molecule that switches on a muscle transcriptional programme closely resembling the body's response to aerobic exercise. The idea is appealing: ERRs, together with the coactivator PGC-1α, govern genes for mitochondrial biogenesis and fatty-acid oxidation, and exercise raises PGC-1α specifically.
The problem was never the receptor, it was pharmacokinetics. SLU-PP-332 is rapidly degraded by hepatic enzymes, so studies had to dose it by injection. Tolerable for a chemical probe; not for anything more ambitious.
The swap the chemists made
In 2023 Hampton and colleagues published work in the European Journal of Medicinal Chemistry describing an entirely new series of pan-ERR agonists. The key finding was elegant: the phenolic or aniline group, precisely the fragments metabolism grabbed most eagerly, could be replaced with a boronic acid. Receptor activity was preserved, while stability in human and mouse liver microsomes rose to T½ ≥ 60 min.
That produced SLU-PP-915. Worth emphasising: this is not "332 with minor edits". Its scaffold is different, thiophene rather than acylhydrazone, and so is its formula (C₁₇H₁₃BFNO₃S, ~341 g/mol). The authors of the follow-up paper describe 915 explicitly as a chemically distinct pan-ERR agonist. Potency in cell-based reporter assays is EC₅₀ around 414, 435 and 378 nM at ERRα, ERRβ and ERRγ.
Boron in drugs is not exotic: it works in bortezomib and tavaborole. Here the boronic acid serves as a bioisostere of a hydroxyl, it occupies the same position and does roughly the same job, but resists metabolic conjugation.
What the mice showed
The test came in 2026 in the Journal of Pharmacology and Experimental Therapeutics. In male C57BL/6 mice, orally administered SLU-PP-915 increased aerobic exercise capacity, meaning the entire point of the chemistry campaign had been achieved.
The molecular marker was more interesting. Both 332 and 915 robustly induced the Ddit4 gene in muscle, at levels matching or exceeding actual treadmill running. By that readout, the pharmacological signal was comparable to physical exercise.
The twist: it is not a replacement for training
The most interesting result usually gets lost in retellings. When SLU-PP-915 was given to mice that were already training, it did not simply duplicate the effect, it further enhanced Ddit4 and mitochondrial gene expression beyond what training alone produced.
That distinction matters. The popular framing of exercise mimetics is "a pill instead of the gym". The data instead describe something closer to an amplifier of training adaptation. In a preclinical model, in mice, over a short window, but that is how it looks in the published results, and it is not worth swapping that picture for a simpler one.
Why anti-doping labs got there first
There is a detail in 915's biography that most research reagents lack. Before the compound had even a hint of a clinical path, anti-doping chemists took up its metabolism.
Möller, Krug and Thevis incubated 332 and 915 with human liver microsomes and S9 fractions and described seven Phase-I metabolites of 915, synthesising three of them to confirm the structures. The main routes are amide hydrolysis, oxidation of the boronic acid and hydroxylation. No Phase-II products were found.
The purpose was pre-emptive: to prepare mass-spectrometric screening targets in advance. SLU-PP-915 is not currently on the WADA (World Anti-Doping Agency) Prohibited List, but non-approved substances with performance-enhancing potential land there regularly. For a laboratory planning work with this compound, that is simply a fact worth knowing.
The limits of what we know
Directness is required here. There are no human studies of SLU-PP-915 at all, not on efficacy, not on safety, not on pharmacokinetics. There is no established human dose. Chronic toxicology is unpublished, and ERRα is expressed in muscle and also in heart, kidney and a range of tumours, so the consequences of sustained systemic pan-ERR activation are simply unknown.
Add that most available data come from a single research programme, and independent replication is still lacking. That is a normal state for a compound at this stage, but it is genuinely an early stage, not a nearly-finished drug.
See also: a general overview of SLU-PP-915 as an orally bioavailable ERR agonist.
SLU-PP-915 is supplied strictly for laboratory research use (RUO): not a medicine, supplement or food, and not for human or veterinary consumption. The full breakdown is in the SLU-PP-915 monograph; the series predecessor is SLU-PP-332; the whole category is ERR agonists.
