Extracting Knowledge From Scientific Texts on Patient-Derived Cancer Models Using Large Language Models: Algorithm Development and Validation Study.

Background: Patient-derived cancer models (PDCMs) have become essential tools in cancer research and preclinical studies. Consequently, the number of publications on PDCMs has increased significantly over the past decade. Advances in artificial intelligence, particularly in large language models (LLMs), offer promising solutions for extracting knowledge from scientific literature at scale. Objective: This study aims to investigate LLM-based systems, focusing specifically on prompting techniques for the automated extraction of PDCM-related entities from scientific texts. Methods: We explore 2 LLM-prompting approaches. The classic method, direct prompting, involves manually designing a prompt. Our direct prompt consists of an instruction, entity-type definitions, gold examples, and a query. In addition, we experiment with a novel and underexplored prompting strategy-soft prompting. Unlike direct prompting, soft prompts are trainable continuous vectors that learn from provided data. We evaluate both prompting approaches across state-of-the-art proprietary and open LLMs. Results: We manually annotated 100 abstracts of PDCM-relevant papers, focusing on PDCM papers with data deposited in the CancerModels.Org platform. The resulting gold annotations span 15 entity types for a total 3313 entity mentions, which we split across training (2089 entities), development (542 entities) and held-out, eye-off test (682 entities) sets. Evaluation includes the standard metrics of precision or positive predictive value, recall or sensitivity, and F1-score (harmonic mean of precision and recall) in 2 settings: an exact match setting, where spans of gold and predicted annotations have to match exactly, and an overlapping match setting, where the spans of gold and predicted annotations have to overlap. GPT4-o with direct prompting achieved F1-scores of 50.48 and 71.36 for exact and overlapping match settings, respectively. In both evaluation settings, LLaMA3 soft prompting improved performance over direct prompting (F1-score from 7.06 to 46.68 in the exact match setting; and 12.0 to 71.80 in the overlapping evaluation setting). Results with LLaMA3 soft prompting are slightly higher than GPT4-o direct prompting in the overlapping match evaluation setting. Conclusions: We investigated LLM-prompting techniques for the automatic extraction of PDCM-relevant entities from scientific texts, comparing the traditional direct prompting approach with the emerging soft prompting method. In our experiments, GPT4-o demonstrated strong performance with direct prompting, maintaining competitive results. Meanwhile, soft prompting significantly enhanced the performance of smaller open LLMs. Our findings suggest that training soft prompts on smaller open models can achieve performance levels comparable to those of proprietary very large language models.