Bioinfo Chem
Generative Flow Networks in Molecular Generation: Stochastic Sampling, Multi-objective Optimization, and Drug Discovery Applications
Mohd Hasan Mujahid 1, Salaman Ahamad 1, Shaista Fatima 1*
Bioinfo Chem 5 (1) 1-8 https://doi.org/10.25163/bioinformatics.5110725
Submitted: 19 June 2023 Revised: 10 August 2023 Accepted: 14 August 2023 Published: 16 August 2023
Abstract
Generative Flow Networks (GFlowNets) are emerging as a promising framework for molecular generation and drug discovery, addressing key challenges in exploring vast chemical space. Despite significant advances in computational drug design, traditional approaches—including variational autoencoders, reinforcement learning, and Markov Chain Monte Carlo methods—often struggle to balance diversity and optimization, leading to limited exploration of high-quality molecular candidates. This review examines how Generative Flow Networks introduce a stochastic sampling paradigm in which molecular structures are generated proportionally to a defined reward function. Unlike conventional optimization methods that converge toward a single solution, GFlowNets maintain a diverse distribution of candidate molecules, enabling more effective exploration of chemical space. This property is particularly advantageous in multi-objective optimization settings, where factors such as binding affinity, drug-likeness, and synthetic feasibility must be simultaneously considered. Across recent studies, GFlowNets demonstrate improved performance in molecular generation tasks, offering a balance between exploration and exploitation that is difficult to achieve with existing machine learning approaches. However, challenges remain, particularly in reward function design, proxy model accuracy, and computational scalability. Overall, Generative Flow Networks represent a shift toward stochastic, distribution-based molecular discovery, providing a flexible and scalable framework for navigating chemical space in drug discovery and AI-driven molecular design.
Keywords: Generative Flow Networks; Molecular Discovery; Stochastic Sampling; Drug Design; Multi-objective Optimization
References
Battaglia, P. W., Hamrick, J. B., Bapst, V., Sanchez-Gonzalez, A., Zambaldi, V., Malinowski, M., Tacchetti, A., Raposo, D., Santoro, A., Faulkner, R., et al. (2018). Relational inductive biases, deep learning, and graph networks. arXiv preprint arXiv:1806.01261.
Bemis, G. W., & Murcko, M. A. (1996). The properties of known drugs. 1. Molecular frameworks. Journal of Medicinal Chemistry, 39(15), 2887–2893. https://doi.org/10.1021/jm9602928
Bickerton, G. R., Paolini, G. V., Besnard, J., Sorel, M., & Hopkins, A. L. (2012). Quantifying the chemical beauty of drugs. Nature Chemistry, 4(2), 90–98. https://doi.org/10.1038/nchem.1243
Bishop, C. M. (2006). Pattern recognition and machine learning. Springer.
Blei, D. M., Kucukelbir, A., & McAuliffe, J. D. (2017). Variational inference: A review for statisticians. Journal of the American Statistical Association, 112(518), 859–877. https://doi.org/10.1080/01621459.2017.1285773
Blum, L. C., & Reymond, J.-L. (2009). 970 million druglike small molecules for virtual screening in the chemical universe database GDB-13. Journal of the American Chemical Society, 131, 8732. https://doi.org/10.1021/ja902302h
Brooks, S. (1998). Markov chain Monte Carlo method and its application. Journal of the Royal Statistical Society: Series D (The Statistician), 47(1), 69–100. https://doi.org/10.1111/1467-9884.00117
Coello Coello, C. A., & Sierra, M. R. (2004). A study of the parallelization of a coevolutionary multi-objective evolutionary algorithm. MICAI 2004: Advances in Artificial Intelligence, 688–697. https://doi.org/10.1007/978-3-540-24694-7_71
Durant, J. L., Leland, B. A., Henry, D. R., & Nourse, J. G. (2002). Reoptimization of MDL keys for use in drug discovery. Journal of Chemical Information and Computer Sciences, 42(6), 1273–1280. https://doi.org/10.1021/ci010132r
Ertl, P., & Schuffenhauer, A. (2009). Estimation of synthetic accessibility score of drug-like molecules based on molecular complexity and fragment contributions. Journal of Cheminformatics, 1(1), 8. https://doi.org/10.1186/1758-2946-1-8
Goodfellow, I. J., Pouget-Abadie, J., Mirza, M., Xu, B., Warde-Farley, D., Ozair, S., Courville, A., & Bengio, Y. (2014). Generative adversarial nets. Neural Information Processing Systems (NeurIPS).
Haarnoja, T., Zhou, A., Abbeel, P., & Levine, S. (2018). Soft actor-critic: Off-policy maximum entropy deep reinforcement learning with a stochastic actor. International Conference on Machine Learning (ICML).
Hastings, W. K. (1970). Monte Carlo sampling methods using Markov chains and their applications. Biometrika, 57(1), 97–109. https://doi.org/10.1093/biomet/57.1.97
Hinton, G. E., Dayan, P., Frey, B. J., & Neal, R. M. (1995). The “wake-sleep” algorithm for unsupervised neural networks. Science, 268(5214), 1158–1161. https://doi.org/10.1126/science.7761831
Hoffman, M. D., Blei, D. M., Wang, C., & Paisley, J. W. (2013). Stochastic variational inference. Journal of Machine Learning Research, 14, 1303–1347.
Ishibuchi, H., Masuda, H., Tanigaki, Y., & Nojima, Y. (2015). Modified distance calculation in generational distance and inverted generational distance. Evolutionary Multi-Criterion Optimization, 110–125. https://doi.org/10.1007/978-3-319-15892-1_8
Jamil, M., & Yang, X. S. (2013). A literature survey of benchmark functions for global optimization problems. International Journal of Mathematical Modelling and Numerical Optimisation, 4(2), 150–194. https://doi.org/10.1504/IJMMNO.2013.055204
Jin, W., Barzilay, R., & Jaakkola, T. (2018). Junction tree variational autoencoder for molecular graph generation. International Conference on Machine Learning (ICML).
Jordan, M. I., Ghahramani, Z., Jaakkola, T., & Saul, L. K. (2004). An introduction to variational methods for graphical models. Machine Learning, 37, 183–233. https://doi.org/10.1023/A:1007665907178
Kingma, D. P., & Welling, M. (2014). Auto-encoding variational Bayes. International Conference on Learning Representations (ICLR).
Kumar, A., Voet, A., & Zhang, K. Y. J. (2012). Fragment based drug design: From experimental to computational approaches. Current Medicinal Chemistry, 19(30), 5128–5147. https://doi.org/10.2174/092986712803530467
Loshchilov, I., & Hutter, F. (2017). SGDR: Stochastic gradient descent with warm restarts. International Conference on Learning Representations (ICLR).
Minka, T. P. (2005). Divergence measures and message passing. Microsoft Research Technical Report.
Mnih, V., Badia, A. P., Mirza, M., Graves, A., Lillicrap, T., Harley, T., Silver, D., & Kavukcuoglu, K. (2016). Asynchronous methods for deep reinforcement learning. International Conference on Machine Learning (ICML).
Montavon, G., Rupp, M., Gobre, V., Vazquez-Mayagoitia, A., Hansen, K., Tkatchenko, A., Müller, K. R., & von Lilienfeld, O. A. (2013). Machine learning of molecular electronic properties in chemical compound space. New Journal of Physics, 15(9). https://doi.org/10.1088/1367-2630/15/9/095003
Morgan, H. L. (1965). The generation of a unique machine description for chemical structures: A technique developed at Chemical Abstracts Service. Journal of Chemical Documentation, 5(2), 107–113. https://doi.org/10.1021/c160017a018
Schulman, J., Levine, S., Abbeel, P., Jordan, M., & Moritz, P. (2015). Trust region policy optimization. International Conference on Machine Learning (ICML).
Schulman, J., Wolski, F., Dhariwal, P., Radford, A., & Klimov, O. (2017). Proximal policy optimization algorithms. arXiv preprint arXiv:1707.06347.
Schütze, O., Esquivel, X., Lara, A., & Coello Coello, C. A. (2012). Using the averaged Hausdorff distance as a performance measure in evolutionary multiobjective optimization. IEEE Transactions on Evolutionary Computation, 16(4), 504–522. https://doi.org/10.1109/TEVC.2011.2161872
Shahriari, B., Swersky, K., Wang, Z., Adams, R. P., & De Freitas, N. (2015). Taking the human out of the loop: A review of Bayesian optimization. Proceedings of the IEEE, 104(1), 148–175. https://doi.org/10.1109/JPROC.2015.2494218
Sutton, R. S., & Barto, A. G. (2018). Reinforcement learning: An introduction. MIT Press.
Sutton, R. S., & Barto, A. G. (2018). Reinforcement learning: An introduction (2nd ed.). MIT Press.
Trott, O., & Olson, A. J. (2010). AutoDock Vina: Improving the speed and accuracy of docking with a new scoring function, efficient optimization, and multithreading. Journal of Computational Chemistry, 31(2), 455–461. https://doi.org/10.1002/jcc.21334
Trott, O., & Olson, A. J. (2010). AutoDock Vina: Improving the speed and accuracy of docking with a new scoring function, efficient optimization, and multithreading. Journal of Computational Chemistry, 31(2), 455–461. https://doi.org/10.1002/jcc.21334
Van Veldhuizen, D. A. (1999). Multiobjective evolutionary algorithms: Classifications, analyses, and new innovations. Air Force Institute of Technology. https://doi.org/10.1145/298151.298382
Weininger, D. (1988). SMILES, a chemical language and information system. 1. Introduction to methodology and encoding rules. Journal of Chemical Information and Computer Sciences, 28(1), 31–36. https://doi.org/10.1021/ci00057a005
Willett, P., Barnard, J. M., & Downs, G. M. (1998). Chemical similarity searching. Journal of Chemical Information and Computer Sciences, 38(6), 983–996. https://doi.org/10.1021/ci9800211
Williams, R. J. (1992). Simple statistical gradient-following algorithms for connectionist reinforcement learning. Reinforcement Learning, 5–32. https://doi.org/10.1007/978-1-4615-3618-5_2
Williams, R. J. (1992). Simple statistical gradient-following algorithms for connectionist reinforcement learning. Machine Learning, 8(3), 229–256. https://doi.org/10.1023/A:1022672621406
Zadeh, J. N., Steenberg, C. D., Bois, J. S., Wolfe, B. R., Pierce, M. B., Khan, A. R., Dirks, R. M., & Pierce, N. A. (2011). NUPACK: Analysis and design of nucleic acid systems. Journal of Computational Chemistry, 32(1), 170–173. https://doi.org/10.1002/jcc.21596
Zhou, W., Saran, R., & Liu, J. (2017). Metal sensing by DNA. Chemical Reviews, 117(12), 8272–8325. https://doi.org/10.1021/acs.chemrev.7b00063
Recommended articles
Artificial Intelligence in Drug Discovery: Systematic Review and Meta-Analysis of Predictive Performance, Structural Modeling, and Translational Reliability
Advances in Molecular Docking for Allosteric Drug Discovery: Ensemble Modeling, Molecular Dynamics, and Artificial Intelligence
Save
Citation
View
Share