Assessing scale and predictive diversity in models for single-cell transcriptomics based on Geneformer.

Single-cell transcriptomic data provide critical insights into cellular states and disease mechanisms, and foundation models have recently emerged as powerful tools for learning gene-gene relationships from these data. However, current approaches often overlook key challenges, including the mismatch between model design and the rank-ordered structure of gene expression profiles, as well as the unclear benefits of large-scale pretraining for biological applications. Here, we present GFCAB, a modified modeling framework designed to better capture the structural properties of ranked single-cell transcriptomic data. GFCAB incorporates a cumulative assignment mechanism to suppress repeated gene predictions and a similarity-based regularization strategy to promote diversity in model outputs. Across multiple evaluation settings, including pretraining behavior, biologically relevant classification tasks, and cross-dataset analyzes, GFCAB consistently reduces redundancy and enhances the recovery of low-frequency genes with known functional and disease relevance while maintaining or improving predictive accuracy. In downstream applications, including classification and zero-shot batch effect correction, the model achieves competitive or improved performance compared to existing approaches. We further show that indiscriminately increasing the pretraining data scale does not uniformly improve performance. Instead, models trained on substantially smaller datasets can match or exceed the performance of larger models and often demonstrate improved generalization across datasets. Together, these findings highlight the importance of aligning model design with the intrinsic structure of biological data and suggest that architectural innovation can reduce reliance on large-scale training data. GFCAB provides a framework for developing more efficient and biologically informative models for single-cell analysis, with potential applications in disease characterization and precision biology.