On the Selectivity of Generative Models in Structure-Based Drug Design
Authors: Ella Miray Rajaonson, Jungyoon Lee, William Chau, Alan Aspuru-Guzik, Benjamin Sanchez-Lengeling, Dominique Beaini, Kirill Neklyudov, Marta Skreta
Organizations: University of Toronto · Vector Institute · Université de Montréal · Mila – Québec AI Institute · NVIDIA · Acceleration Consortium · CIFAR · Valence Labs · Institut Courtois
Designing small-molecule drugs that selectively bind to a target protein while avoiding unintended interactions with other proteins is essential for reducing side effects that contribute substantially to clinical attrition. Although structure-based drug design (SBDD) has advanced rapidly with deep learning, most generative models still optimize binding to a single target and disregard selectivity due to limited training data and unknown off-target interactions. Motivated by this gap, we introduce SELECTBENCH, a comprehensive benchmark assessing the selectivity of generative SBDD models. SELECTBENCH provides three curated evaluation tasks reflecting different real-world drug discovery scenarios: literature-based case studies, safety screening panels used in pharmaceutical development, and large-scale structure-based evaluation sets. We further introduce a suite of metrics to quantify selectivity and conduct a systematic evaluation of nine representative SBDD models, including methods explicitly trained for selectivity and widely-used inference-time guidance techniques. Our results show that even selectivity-trained models achieve only modest off-target discrimination and inference-time guidance provides limited gains, underscoring the need for method improvement. SELECTBENCH provides both a characterization of where current generative SBDD stands on selectivity and an open, extensible platform to accelerate progress. The benchmark is available at https://github.com/lovetaro/selectbench.
Figures & tables
Figure 1: Off-target interactions are a major consideration in real-world drug design (top left) and often not accounted for in current generative SBDD (top right). SelectBench provides tasks, metrics, and baselines to assess selectivity in generative SBDD (bottom).
Figure 2: SelectBench task summary. SelectBench -Case focuses on case studies, SelectBench -Safety models safety screening, and SelectBench -XL enables large-scale evaluation.
On-Target Gene
On-Target Application
Off-Target Gene
Off-Target Effect
Computational study
PARP1
Cancer [ 52 ]
PARP2
Hematological toxicity [ 52 ]
CMD-GEN [ 74 ]
BMP2K
Antiviral [ 28 ]
TTK
Hematological toxicity, neutropenia [ 6 ]
DiffSBDD [ 63 ]
CDK9
Cancer [ 51 ]
CDK2
Hematological toxicity, GI issues [ 34 ]
Alchemical free-energy [ 3 ]
MAPK1
Cancer [ 60 ]
CDK2
Hematological toxicity, GI issues [ 34 ]
Alchemical free-energy [ 3 ]
DRD2
Neuropsychiatric [ 72 ]
HRH1
Hypertension, neutropenia [ 23 ]
Docking [ 68 ]
Table 1: Summary of case studies in SelectBench -Case.
Table 2: Summary of baseline models evaluated in SelectBench .
Figure 3: Baseline performances on SelectBench -Case The mean performance is reported across Δˉtop-10z ( ↑ ) and SRτ=1z ( ↑ ) for each baseline on each on-/off-target pair in SelectBench -Case. The color of the marker indicates the model type, and its shape indicates if inference-time methods were additionally employed. Data points in the top-right region indicate better performance.
Figure 4: Baseline performances on SelectBench -Safety-Priority. The mean performance is reported across R20z(↑) and SRτ=1z, avg(↑) for each baseline on each on-target POI/priority off-targets case in SelectBench -Safety-Priority. The color of the marker indicates the model type, and its shape indicates if inference-time methods were additionally employed. Data points in the top-right region indicate better performance.
Figure 5: Baseline performances on SelectBench -XL The mean performance is reported across Δˉtop-10z ( ↑ ) and SRτ=1z ( ↑ ) for each baseline on each on-/off-target pairs in SelectBench -XL by difficulty. The color of the marker indicates the model type, and its shape indicates if inference-time methods were additionally employed. Data points in the top-right region indicate better performance.
Figure 6: Multi-objective metrics exploration on one case study of SelectBench -Case The mean performance is reported across Δz ( ↑ ), −son ( ↑ ) and SA ( ↑ ) for each baseline on the PARP1/PARP2 case study The color of the marker indicates the model type, and its shape indicates if inference-time methods were additionally employed. Data points in the top-right region indicate better performance. The potency/selectivity trend in can be captured by introducing the potency-and-selectivity metric PS=−son∗Δz ( ↑ ). We report PS across all other evaluation tasks in SelectBench in App. G . Additional metrics assessing the quality of generated molecules beyond selectivity and potency for each task are reported in App. H .
Appendix figures & tables19 assets
Supplementary material from the paper’s appendix.
Appendix
ID
On-target
Off-target
ID
On-target
Off-target
ID
On-target
Off-target
717
4tqr_A
14gs_A
3498
1r1h_A
2rma_A
2308
1coy_A
2pqw_A
823
1h0i_A
14gs_A
4773
5mgl_A
4keu_A
2508
2jjg_A
1djy_A
981
4rlu_A
2v3r_A
4886
4q8b_B
3ej8_A
2515
2rma_A
2jjg_A
2167
4zfa_A
3g51_A
5895
1k9t_A
4p6p_A
2978
2pqw_A
3pnm_A
2219
4kcq_A
3g51_A
6354
4lfu_A
3l3n_A
3311
2pc8_A
5bur_A
8550
1ai4_A
3hy9_B
8989
4gvd_A
5mgl_A
9741
3af2_A
3u9f_C
Appendix
Table A1: Easy pairs sampled from SelectBench -XL
sˉon
Δˉ
SRτ=0
SRτ=1
sˉonz
Δˉz
SRτ=0z
SRτ=1z
−11.008±0.969
−0.033±0.502
0.556
0.000
−1.631±1.009
0.207±0.540
0.667
0.111
Appendix
Table A2: PARP1/PARP2 positive control evaluation We report: the mean on-target Vina score sˉon ( ↓ ); Δˉ over selected molecules and the selectivity ratio SRτ for τ∈{0,1} kcal/mol. Additionally, we report the z-score normalized analogues of the corresponding raw metrics, standardized against a reference score distribution: sˉonz , Δˉz , SRτ=0z and SRτ=1z .
Ligands
sˉon
Δˉ
SRτ=0
SRτ=1
sˉonz
Δˉz
SRτ=0z
SRτ=1z
CDK9-selective
−8.050±0.121
−0.691±0.365
0.000
0.000
−0.117±0.166
0.172±0.439
0.750
0.000
CDK9 non-selective
−7.822±0.741
−1.074±0.594
0.000
0.000
0.195±1.014
−0.323±0.648
0.250
0.000
Appendix
Table A3: CDK9/CDK2 positive control evaluation We report: the mean on-target Vina score sˉon ( ↓ ); Δˉ over selected molecules and the selectivity ratio SRτ for τ∈{0,1} kcal/mol. Additionally, we report the z-score normalized analogues of the corresponding raw metrics, standardized against a reference score distribution: sˉonz , Δˉz , SRτ=0z and SRτ=1z .
Method
SelectBench -Case
SelectBench -Safety
SelectBench -XL
DecompDiff
2.4%
3.5%
3.1%
DiffSBDD
1.6%
1.4%
5.2%
TargetDiff
0.6%
0.7%
2.3%
MolSnapper
2.5%
5.4%
6.7%
MolForm
0.6%
2.2%
9.2%
Pocket2Mol
0.6%
0.4%
0.4%
Appendix
Table A4: Pre-docking failure rates by method and evaluation track. Failures occur when a wrapper-validated molecule is rejected by Meeko/RDKit ligand preparation before AutoDock Vina runs. Aggregated as 1−(Ndocked/Ngenerated) over all (method, target) cells in each track. SelectBench -Safety totals are computed over the full 85-pair panel.
Method
sˉon(↓)
Δˉ(↑)
Δˉtop-5(↑)
Δˉtop-10(↑)
SRτ=0(↑)
SRτ=1(↑)
sˉonz(↓)
Δˉz(↑)
SRτ=0z(↑)
SRτ=1z(↑)
\hlcustom Blue1 Case: PARP1 (on) / PARP2 (off)
Standard SBDD models
DecompDiff
−7.43±0.57
−0.03±0.42
1.05
0.84
0.41
0.02
2.15±0.60
0.02±0.41
0.46
0.04
DiffSBDD
−8.44±1.67
−0.05±0.43
0.90
0.77
0.46
0.01
1.09±1.76
0.08±0.43
0.57
0.03
TargetDiff
−8.56±1.22
0.07±0.54
1.52
1.16
0.55
0.05
0.96±1.28
0.20±0.53
0.67
0.07
MolForm
−8.30±1.23
−0.27±0.43
0.59
0.45
0.29
0.00
1.24±1.29
−0.15±0.44
0.37
0.00
Appendix
Table A5: SelectBench -Case evaluation. For each method, we report: the mean on-target Vina score sˉon ( ↓ ); Δˉ over valid molecules; the mean of the k largest Δ(i) ( k=5,10 ) Δˉtop-k ; the selectivity ratio SRτ for τ∈{0,1} kcal/mol. Additionally, we report the z-score normalized analogues of the corresponding raw metrics, standardized against a reference score distribution: sˉonz , Δˉz , SRτ=0z , SRτ=1z . The τ=1 cutoff in z-space corresponds to Δz≥1 (one reference- σ in the off-target’s own scale).
Method
sˉon(↑)
Δˉ(↑)
Δˉtop-5(↑)
Δˉtop-10(↑)
SRτ=0rank(↑)
SRson>0.6,soff<0.4(↑)
SRpon>0.6,poff<0.4rank(↑)
\hlcustom Blue1 Case: PARP1 (on) / PARP2 (off)
Standard SBDD models
DecompDiff
0.396±0.126
0.085±0.083
0.257
0.241
0.490
0.010
0.080
DiffSBDD
0.421±0.214
0.050±0.094
0.300
0.253
0.444
0.010
0.020
TargetDiff
0.372±0.158
0.069±0.088
0.284
0.241
0.500
0.010
0.030
MolForm
0.323±0.162
0.038±0.070
0.174
0.163
0.500
0.000
0.010
Appendix
Table A6: SelectBench -Case Boltz-2 evaluation. For each method, we report: the mean on-target predicted probability score sˉon ( ↑ ); Δˉ over valid molecules; the mean of the k largest Δ(i) ( k=5,10 ) Δˉtop-k ; the selectivity ratio SRτ=0rank over percentile-normalized ranks as well as the threshold-based SR over predicted binding probabilities SRτon=0.6,τoff=0.4 and percentile-normalized ranks SRτon=0.6,τoff=0.4rank
Method
sˉon(↓)
Δˉworst-mol(↑)
SRτ=0worst-mol(↑)
SRτ=1worst-mol(↑)
R20(↑)
sˉonz(↓)
Δˉz(↑)
SRτ=0z,avg(↑)
SRτ=1z,avg(↑)
R20z(↑)
\hlcustom Blue1 POI: 5HT1B (priority)
Standard SBDD models
DecompDiff
−6.73±1.69
−1.16±1.71
0.24
0.02
0.64
2.45±1.75
0.74±1.85
0.68
0.44
0.43
DiffSBDD
−6.83±1.76
−1.32±1.05
0.07
0.00
0.38
2.34±1.82
−0.08±1.18
0.51
0.21
0.21
TargetDiff
−7.21±1.53
−1.20±1.42
0.19
0.04
0.50
1.95±1.59
1.04±1.77
0.65
0.41
0.35
MolForm
−7.00±2.64
−2.00±2.27
0.09
0.02
0.45
2.17±2.73
0.72±2.01
0.63
0.40
0.34
Appendix
Table A7: SelectBench -Safety-Priority evaluation For each method, we report: the mean on-target Vina score sˉon ( ↓ ); the worst per-molecule Δˉworst-mol averaged across T=22 off-targets (least Selectivity-trained models); the fraction of molecules SRτ=0worst-mol / SRτ=1worst-mol whose worst per-target Δ is ≥0 / ≥1 , respectively; the fraction R20 of ligands whose on-target ranks in the top-20% across all 23 targets. Additionally, we report the z-score normalized analogues of the corresponding raw metrics, standardized against a reference score distribution: sˉonz , Δˉz , SRτ=0z,avg , SRτ=1z,avg , R20z . SRτz,avg is the panel-average of per-target z-SRs. τ=1 in z-space corresponds to one reference- σ margin in the off-target’s own scale
Figure A1: Baseline performances on SelectBench -Safety-All The mean performance is reported across R20z(↑) and SRτ=1avg(↑) for each baseline on each on-target POI/all off-targets case in SelectBench -Safety-All. The color of the marker indicates the model type, and its shape indicates if inference-time methods were additionally employed. Data points in the top-right region indicate better performance.
Method
sˉon(↓)
Δˉworst-mol(↑)
SRτ=0worst-mol(↑)
SRτ=1worst-mol(↑)
R20(↑)
sˉonz(↓)
Δˉz(↑)
SRτ=0z,avg(↑)
SRτ=1z,avg(↑)
R20z(↑)
\hlcustom Blue1 POI: 5HT1B
Standard SBDD models
DecompDiff
−6.73±1.69
−1.60±1.68
0.11
0.01
0.70
2.45±1.75
0.61±1.79
0.66
0.41
0.44
DiffSBDD
−6.83±1.76
−1.57±0.99
0.00
0.00
0.44
2.34±1.82
−0.13±1.12
0.50
0.19
0.19
TargetDiff
−7.21±1.53
−1.54±1.32
0.06
0.01
0.62
1.95±1.59
0.79±1.56
0.64
0.37
0.35
MolForm
−7.00±2.64
−2.35±2.20
0.02
0.00
0.55
2.17±2.73
0.56±1.92
0.61
0.38
0.33
Appendix
Table A8: SelectBench -Safety-All evaluation. For each method, we report: the mean on-target Vina score sˉon ( ↓ ); the worst per-molecule Δˉworst-mol averaged across T=22 off-targets (least Selectivity-trained models); the fraction of molecules SRτ=0worst-mol / SRτ=1worst-mol whose worst per-target Δ is ≥0 / ≥1 , respectively; the fraction R20 of ligands whose on-target ranks in the top-20% across all 23 targets. Additionally, we report the z-score normalized analogues of the corresponding raw metrics, standardized against a reference score distribution: sˉonz , Δˉz , SRτ=0z,avg , SRτ=1z,avg , R20z . SRτz,avg is the panel-average of per-target z-SRs. τ=1 in z-space corresponds to one reference- σ margin in the off-target’s own scale
Method
sˉon(↓)
Δˉ(↑)
Δˉtop-5(↑)
Δˉtop-10(↑)
SRτ=0(↑)
SRτ=1(↑)
sˉonz(↓)
Δˉz(↑)
SRτ=0z(↑)
SRτ=1z(↑)
\hlcustom Blue1 Hard
Standard SBDD models
DecompDiff
−5.48±0.66
0.10±0.40
0.85
0.74
0.51
0.09
3.39±0.76
0.07±0.45
0.53
0.12
DiffSBDD
−5.98±1.16
0.08±0.46
1.12
0.92
0.54
0.06
2.76±1.37
0.07±0.53
0.53
0.09
TargetDiff
−6.42±1.15
0.12±0.57
1.27
1.08
0.55
0.11
2.24±1.32
0.10±0.62
0.55
0.11
MolForm
−6.75±1.30
0.10±0.52
1.13
0.97
0.53
0.10
1.89±1.51
0.10±0.58
0.53
0.11
Appendix
Table A9: SelectBench -XL evaluation. Metrics are defined as in the case-study table and computed per on-/off-target pair. Values are means over all pairs in the tier; where shown, ± is the standard deviation across molecules within a pair, averaged over pairs. sˉonz , Δˉz , SRτ=0z , SRτ=1z : z-score variants computed against per-pocket reference distributions; τ=1 in z-space corresponds to one reference- σ margin.
Method
\hlcustom Blue1 PARP1
\hlcustom Pink1 BMP2K
\hlcustom Yellow2 CDK9
\hlcustom Purple1 ERK2
\hlcustom Blue2 DRD2
Standard SBDD models
DecompDiff
0.14
−3.63
0.49
0.74
−8.27
DiffSBDD
0.65
1.13
−0.05
−0.16
−6.87
TargetDiff
1.74
−0.16
2.10
0.50
−4.11
MolForm
−1.23
−2.76
1.04
3.09
−0.28
MolSnapper
0.91
0.82
0.53
1.25
−8.65
Appendix
Table A10: SelectBench -Case potency and selectivity evaluation. For each method, we report PS ; higher values indicate methods yielding jointly potent and selective molecules.
Method
\hlcustom Blue1 PARP1
\hlcustom Pink1 JAK2
\hlcustom Yellow2 BRAF
\hlcustom Purple1 5-HT1B
\hlcustom Blue2 FA7
Standard SBDD models
DecompDiff
−4.23
0.91
−1.86
4.09
−1.79
DiffSBDD
2.81
2.03
−1.17
−0.88
−1.73
TargetDiff
6.09
1.01
1.20
5.70
1.78
MolForm
8.36
3.25
7.25
3.89
−1.41
MolSnapper
1.87
−1.45
0.57
−2.77
3.32
Appendix
Table A11: SelectBench -Safety potency and selectivity evaluation. For each method, we report PS ; higher values indicate methods yielding jointly potent and selective molecules.
Method
\hlcustom Blue1 Easy
\hlcustom Pink1 Medium
\hlcustom Yellow2 Hard
Standard SBDD models
DecompDiff
1.98
0.59
0.38
DiffSBDD
0.36
0.48
0.42
TargetDiff
0.19
1.14
0.64
MolForm
0.50
1.20
0.68
MolSnapper
0.86
0.07
0.78
Appendix
Table A12: SelectBench -XL potency and selectivity evaluation. For each method, we report PS ; higher values indicate methods yielding jointly potent and selective molecules.
Method
QED (↑)
SA (↑)
LogP
Lipinski (↑)
MW
Diversity (↑)
\hlcustom Blue1 PARP1 (on) / PARP2 (off)
Standard SBDD models
DecompDiff
0.22±0.12
0.57±0.07
1.75±2.01
3.48±0.74
412.72±18.46
0.799
DiffSBDD
0.39±0.21
0.58±0.12
1.29±1.94
4.16±1.20
415.26±134.94
0.677
TargetDiff
0.25±0.17
0.50±0.09
2.05±1.93
3.42±1.39
495.64±94.75
0.667
MolForm
0.23±0.10
0.56±0.11
9.00±1.43
2.98±0.73
483.83±100.48
0.728
Appendix
Table A13: SelectBench -Safety evaluation on additional molecular generation metrics.
Method
QED (↑)
SA (↑)
LogP
Lipinski (↑)
MW
Diversity (↑)
\hlcustom Blue1 POI: 5HT1B
Standard SBDD models
DecompDiff
0.18±0.09
0.45±0.09
6.31±2.35
2.56±0.75
605.66±10.96
0.662
DiffSBDD
0.43±0.21
0.58±0.14
2.87±1.72
4.44±0.86
405.97±156.40
0.721
TargetDiff
0.36±0.16
0.50±0.13
5.98±2.04
3.51±0.93
495.19±100.06
0.690
MolForm
0.21±0.08
0.52±0.14
11.19±1.55
2.81±0.57
522.51±117.95
0.726
Appendix
Table A14: SelectBench -Safety evaluation on additional molecular generation metrics.
Method
QED (↑)
SA (↑)
LogP
Lipinski (↑)
MW
Diversity (↑)
\hlcustom Blue1 Hard
Standard SBDD models
DecompDiff
0.44±0.12
0.68±0.10
1.92±2.24
4.44±0.77
270.66±163.66
0.80±0.08
DiffSBDD
0.50±0.05
0.64±0.04
0.83±0.82
4.77±0.17
270.73±67.72
0.82±0.05
TargetDiff
0.47±0.07
0.58±0.06
1.44±1.74
4.53±0.32
337.44±110.22
0.72±0.09
MolForm
0.45±0.07
0.67±0.11
5.62±1.93
4.17±0.56
309.89±117.62
0.75±0.08
Appendix
Table A15: SelectBench -Safety evaluation on additional molecular generation metrics.
Figure A2: SelectBench -Case on-/off-target pairs protein structures overlay and their associated similarity. This visually demonstrates the high structural similarity of pairs in SelectBench -Case. Co-crystallized ligands are displayed in yellow sticks. Reported ProBiS Z-scores quantify global structural similarity of the structures, with higher values indicating stronger similarity.
Figure A3: Heatmaps of structural similarity between POIs and the off-targets panel in SelectBench -Safety. Each row corresponds to an on-target, each column corresponds to an off-target, and color intensity reflects the ProBiS Z-score, with darker shades indicating higher local structural similarity. ProBiS Z-score of zero or below are set to white. Priority targets of SelectBench -Safety-Priority are highlighted by the yellow box, the HTR1B off-target structure excluded due to overlap with POI 5HT1B is highlighted by the blue box.
Figure A4: Heatmaps of structural similarity between on-/off-target pairs in SelectBench -XL. Each row corresponds to an on-target, each column corresponds to an off-target, and color intensity reflects the ProBiS Z-score, with darker shades indicating higher local structural similarity. ProBiS Z-score of zero or below are set to white. Grey shade indicates self-pairs, which are excluded from SelectBench -XL.
Computer Science and Engineering, The Ohio State University, Columbus, OH 43210. · Industrial and System Engineering, University of Minnesota, Minneapolis, MN 55455. · Google Cloud, Google LLC, Mountain View, CA 94043. +6