Supervised Training of Conditional Monge Maps
Charlotte BunneAndreas KrauseMarco Cuturi
Introduces CONDOT, a neural optimal transport framework using partially input convex neural networks to learn context-conditioned Monge maps across probability measures, enabling accurate prediction of cellular responses to unseen drug and genetic perturbation combinations.
Predicting how complex biological systems respond to interventions is a major hurdle in personalized medicine and drug development. In cancer therapeutics, single-cell sequencing can measure individual cell behaviors before and after interventions, but the measurement process destroys the cells, leaving before and after populations completely unpaired. Optimal transport provides a mathematical foundation for mapping such unpaired distributions, but existing methods typically calculate a standalone map for a single isolated condition. Because real-world biomedical applications involve varying drug dosages, patient-specific covariates, and vast combinations of genetic or therapeutic treatments, there is an urgent need for models that can incorporate contextual variables and generalize to previously unobserved conditions.
The article introduces a framework designed to estimate a global family of context-conditioned optimal transport maps from labeled population pairs. Its core objective is to accurately map source distributions to target distributions across known conditions while demonstrating the ability to predict the outcomes of unseen contexts and composite perturbations.
To achieve this, the researchers parameterized optimal transport maps as the gradients of partially input convex neural networks, which modulate convex potentials via contextual inputs. Contextual factors—ranging from continuous scalars like dosage to discrete genetic perturbations—are processed through specialized embedding modules and permutation-invariant combination networks. To overcome the known training instability of convex neural architectures, the approach introduces an initialization strategy that mimics closed-form affine transport maps between Gaussian approximations of the source and target distributions. The framework was evaluated across single-cell genomics benchmarks, including thousands of gene expression profiles across diverse drug dosages, distinct cell lines, and nearly one hundred distinct CRISPR-guided genetic perturbations.
The experimental findings highlight substantial improvements in predictive performance. When modeling the response of single cells to varying drug dosages, the context-aware model achieved significantly lower distribution discrepancies on out-of-sample dosages compared to baseline models, reducing marker gene perturbation error metrics by more than half relative to standard architectures. In multi-cell-line benchmarks, the method captured cell-type-specific responses where baseline models failed to match target distribution shifts. Furthermore, on large-scale genetic perturbation screens, the architecture accurately predicted cellular responses to completely unseen perturbation combinations, recovering distinct subpopulations that alternative deep-learning baselines missed entirely.
These results establish that embedding contextual variables directly into transport map estimation enables effective multi-task learning and robust out-of-distribution generalization. For drug discovery and clinical development pipelines, this capability offers a viable route to drastically decrease experimental costs, reduce development timelines, and mitigate the risk of missed therapeutic effects by screening combinatorial interventions computationally before conducting laboratory trials.
Organizations evaluating computational perturbation models should consider piloting this architecture for preclinical drug combination screening and dosage interpolation. Incorporating domain-specific action embeddings or mode-of-action representations is recommended to enhance performance when predicting novel compounds. However, practitioners should maintain reasonable caution: the framework relies on the assumption that underlying population shifts follow optimal transport trajectories, and its predictive accuracy decreases as the combinatorial distance from observed training data grows. Future initiatives should focus on validating predictions through targeted wet-lab follow-up experiments and scaling the framework across larger, multi-modal biological datasets.
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