Aligning LLMs with Biomedical Knowledge using Balanced Fine-Tuning

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Hauptverfasser: Tang, Zhenchao, Wang, Fang, He, Haohuai, Zhou, Jiale, Lv, Tianxu, Zhu, Jun, Chen, Shouzhi, Yang, Minghao, Wang, Yu, Wu, Jiayang, Song, Yidong, Li, Yaokun, Huang, Jiehui, He, Bing, Yao, Jianhua
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Veröffentlicht: 2025
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author Tang, Zhenchao
Wang, Fang
He, Haohuai
Zhou, Jiale
Lv, Tianxu
Zhu, Jun
Chen, Shouzhi
Yang, Minghao
Wang, Yu
Wu, Jiayang
Song, Yidong
Li, Yaokun
Huang, Jiehui
He, Bing
Yao, Jianhua
author_facet Tang, Zhenchao
Wang, Fang
He, Haohuai
Zhou, Jiale
Lv, Tianxu
Zhu, Jun
Chen, Shouzhi
Yang, Minghao
Wang, Yu
Wu, Jiayang
Song, Yidong
Li, Yaokun
Huang, Jiehui
He, Bing
Yao, Jianhua
contents Engineering LLMs to accelerate life sciences research requires a robust alignment with biomedical knowledge. We observe that biomedical text exhibits a fundamentally different uncertainty structure from general text: dense low-confidence runs encode epistemic knowledge gaps (dense causal chains, rare entities) rather than the sparse aleatoric stylistic variation typical of general text. Based on this discovery, we propose Balanced Fine-Tuning (BFT), a dual-scale post-training method that combines group-normalized token reweighting with sequence-level reallocation toward knowledge-dense samples exhibiting dense epistemic uncertainty. Across medical evaluation, biological reasoning, sparse-reward RL, and biological representation tasks, BFT provides more consistent gains than SFT and DFT under a shared training setup. When replacing the default closed-source backbones in GeneAgent (GPT-4o) and VCWorld (Gemini-2.5-Flash), the BFT-aligned 70B model delivers stronger performance across biological process reasoning and chemical perturbation prediction. Critically, all BFT variants further improve after subsequent GRPO with sparse rewards, while SFT and DFT degrade, suggesting that epistemic-aware post-training provides a more robust policy initialization. Beyond text generation, BFT-aligned LLMs produce more accurate and professional biomedical profile texts; after encoding these profiles with a text embedding model, the resulting representations support gene-level, cell-level, and perturbation-response tasks, suggesting that BFT-enhanced generation can facilitate biological representation and, in turn, broader biomedical downstream tasks.
format Preprint
id arxiv_https___arxiv_org_abs_2511_21075
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Aligning LLMs with Biomedical Knowledge using Balanced Fine-Tuning
Tang, Zhenchao
Wang, Fang
He, Haohuai
Zhou, Jiale
Lv, Tianxu
Zhu, Jun
Chen, Shouzhi
Yang, Minghao
Wang, Yu
Wu, Jiayang
Song, Yidong
Li, Yaokun
Huang, Jiehui
He, Bing
Yao, Jianhua
Machine Learning
Artificial Intelligence
Engineering LLMs to accelerate life sciences research requires a robust alignment with biomedical knowledge. We observe that biomedical text exhibits a fundamentally different uncertainty structure from general text: dense low-confidence runs encode epistemic knowledge gaps (dense causal chains, rare entities) rather than the sparse aleatoric stylistic variation typical of general text. Based on this discovery, we propose Balanced Fine-Tuning (BFT), a dual-scale post-training method that combines group-normalized token reweighting with sequence-level reallocation toward knowledge-dense samples exhibiting dense epistemic uncertainty. Across medical evaluation, biological reasoning, sparse-reward RL, and biological representation tasks, BFT provides more consistent gains than SFT and DFT under a shared training setup. When replacing the default closed-source backbones in GeneAgent (GPT-4o) and VCWorld (Gemini-2.5-Flash), the BFT-aligned 70B model delivers stronger performance across biological process reasoning and chemical perturbation prediction. Critically, all BFT variants further improve after subsequent GRPO with sparse rewards, while SFT and DFT degrade, suggesting that epistemic-aware post-training provides a more robust policy initialization. Beyond text generation, BFT-aligned LLMs produce more accurate and professional biomedical profile texts; after encoding these profiles with a text embedding model, the resulting representations support gene-level, cell-level, and perturbation-response tasks, suggesting that BFT-enhanced generation can facilitate biological representation and, in turn, broader biomedical downstream tasks.
title Aligning LLMs with Biomedical Knowledge using Balanced Fine-Tuning
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2511.21075