Blood-brain barrier penetration from structure
Classify whether a compound crosses the blood-brain barrier, scored by AUROC on TDC’s scaffold split of 1,975 drugs.
| 1 | # Blood-brain barrier penetration from structure |
| 2 | |
| 3 | The blood-brain barrier keeps most foreign molecules out of the brain. Drugs for the central nervous system have to cross it; drugs for everything else usually should not. This benchmark asks which way a compound goes, from its structure. |
| 4 | |
| 5 | ## Task |
| 6 | |
| 7 | Given a drug as a SMILES string, predict the binary blood-brain barrier penetration label: $1$ if the compound penetrates, $0$ if it does not. Submissions are scored by AUROC on TDC’s held-out test set, so higher is better. |
| 8 | |
| 9 | ## Background |
| 10 | |
| 11 | Martins et al. (2012) built this set for a Bayesian model of blood-brain barrier penetration, and it later travelled into MoleculeNet as "BBBP"; TDC uses 1,975 of its compounds. The task matters in both directions — getting a neurological drug in, and keeping a peripheral drug out of the brain to avoid central side effects — which is why it appears in nearly every ADMET model comparison. It is also the most contested endpoint in this group, with 26 submissions. |
| 12 | |
| 13 | ## Data and evaluation |
| 14 | |
| 15 | TDC ships the group as one archive (`admet_group`, Harvard Dataverse file 4426004), loaded with |
| 16 | `admet_group(path='data/')` from the `tdc.benchmark_group` module. The group’s `bbb_martins` folder holds 1,624 `train_val` and 406 `test` rows (2,030 rows, 1,975 distinct SMILES, matching TDC’s count of drugs); 76.4% of labels are positive. |
| 17 | |
| 18 | The split is a scaffold split: TDC holds out a fixed 20% test set (here 406 of 2,030 rows in |
| 19 | the group’s files), and the remaining `train_val` part is split again per seed by |
| 20 | `group.get_train_valid_split(benchmark=name, split_type='default', seed=seed)` into 87.5% training |
| 21 | and 12.5% validation. The leaderboard asks for five independent runs with seeds 1, 2, 3, 4 and 5; |
| 22 | `group.evaluate_many` then reports the mean and the standard deviation of the per-seed test scores, |
| 23 | rounded to three decimals. The test set never changes, so only the training split moves with the seed. |
| 24 | |
| 25 | The metric is AUROC, the area under the receiver operating characteristic curve, computed by TDC’s `Evaluator(name='roc-auc')`; it equals the probability that a positive compound is scored above a negative one, and higher is better. Submissions pass continuous scores, not hard labels. |
| 26 | |
| 27 | Official evaluation code: [`tdc/benchmark_group/base_group.py`](https://github.com/mims-harvard/TDC/blob/main/tdc/benchmark_group/base_group.py) |
| 28 | in the TDC repository (MIT licence), whose `evaluate` and `evaluate_many` methods are what the |
| 29 | leaderboard numbers come from. The dataset page gives the licence as "Not Specified. CC BY 4.0". |
| 30 | |
| 31 | ## What is known |
| 32 | |
| 33 | - Best on the leaderboard: MiniMol, AUROC $0.924 \pm 0.003$ (Kläser, Banaszewski et al., 2024). |
| 34 | - Next: CFA, $0.920 \pm 0.006$ (submitted by Nan Jiang), then MapLight, $0.916 \pm 0.001$ (Notwell and Wood, 2023). |
| 35 | - Twenty-six entries are listed, the most of any endpoint in the group, and the top ten are inside $0.02$ AUROC of each other — so progress here is now measured in thousandths. |
| 36 | |
| 37 | ## What would count as progress |
| 38 | |
| 39 | - A mean AUROC on TDC’s fixed test set that beats MiniMol (AUROC 0.924), averaged over the official |
| 40 | seeds 1-5 and produced by `group.evaluate_many`, with the five per-seed numbers reported as well. |
| 41 | - The training and inference code, the environment and the fitted model, so that the five runs can be |
| 42 | repeated end to end from the `train_val` part alone. |
| 43 | - Evidence that the gain is larger than run-to-run noise: the gap between the top two entries here is |
| 44 | 0.004 AUROC, so a difference smaller than the reported standard deviation is not a result. |
| 45 | |
| 46 | ## References |
| 47 | |
| 48 | 1. Martins, I. F. et al., "A Bayesian Approach to in Silico Blood-Brain Barrier Penetration Modeling", *Journal of Chemical Information and Modeling* 52 (2012), 1686–1697. [doi:10.1021/ci300124c](https://doi.org/10.1021/ci300124c) |
| 49 | 2. Wu, Z. et al., "MoleculeNet: a benchmark for molecular machine learning", *Chemical Science* 9 (2018), 513–530. [doi:10.1039/C7SC02664A](https://doi.org/10.1039/C7SC02664A) |
| 50 | 3. Kläser, K., Banaszewski, B. et al., "MiniMol: A Parameter-Efficient Foundation Model for Molecular Learning", arXiv:2404.14986 (2024). [arxiv.org/abs/2404.14986](https://arxiv.org/abs/2404.14986) |
| 51 | 4. Notwell, J. H. and Wood, M. W., "ADMET property prediction through combinations of molecular fingerprints", arXiv:2310.00174 (2023). [arxiv.org/abs/2310.00174](https://arxiv.org/abs/2310.00174) |
| 52 | |
| 53 | ## Source |
| 54 | |
| 55 | Imported from [TDC ADMET benchmark group, BBB_Martins](https://tdcommons.ai/benchmark/admet_group/07bbb/), curated by Therapeutics Data Commons (Harvard). Open according to the source as of 2026-10-20. The statement above is written in our own words; see the source for the original wording, history and discussion. |