Functional Genetic Screening Enables Theranostic Molecular Imaging in Cancer

Abstract

◥Purpose: Targeted therapies for cancer have accelerated the need for functional imaging strategies that inform therapeutic efficacy. This study assesses the potential of functional genetic screening to integrate therapeutic target identification with imaging probe selection through a proof-of-principle characterization of a therapyprobe pair using dynamic nuclear polarization (DNP)-enhanced magnetic resonance spectroscopic imaging (MRSI).Experimental Design: CRISPR-negative selection screens from a public dataset were used to identify the relative dependence of 625 cancer cell lines on 18,333 genes. Follow-up screening was performed in hepatocellular carcinoma with a focused CRISPR library targeting imaging-related genes. Hyperpolarized [1-13 C]-pyruvate was injected before and after lactate dehydrogenase inhibitor (LDHi) administration in male Wistar rats with autochthonous hepatocellular carcinoma. MRSI evaluated intratumoral pyruvate metabolism, while T 2 -weighted segmentations quantified tumor growth.Results: Genetic screening data identified differential metabolic vulnerabilities in 17 unique cancer types that could be imaged with existing probes. Among these, hepatocellular carcinoma required lactate dehydrogenase (LDH) for growth more than the 29 other cancer types in this database. LDH inhibition led to a decrease in lactate generation (P < 0.001) and precipitated dose-dependent growth inhibition (P < 0.01 overall, P < 0.05 for dose dependence). Intratumoral alanine production after inhibition predicted the degree of growth reduction (P < 0.001).Conclusions: These findings demonstrate that DNP-MRSI of LDH activity using hyperpolarized [1-13 C]-pyruvate is a theranostic strategy for hepatocellular carcinoma, enabling quantification of intratumoral LDHi pharmacodynamics and therapeutic efficacy prediction. This work lays the foundation for a novel theranostic platform wherein functional genetic screening informs imaging probe selection to quantify therapeutic efficacy on a cancer-bycancer basis.

Pharmacodynamics and pharmacokinetics of hyperpolarized [1‐13C]‐pyruvate in a translational oncologic model

“…The described experiments present an application of DNP as a means to directly quantify drug pharmacokinetics and pharmacodynamics that are consistent with prior work. 26,40,41 They extend upon the existing literature to confirm, with an independent measurement of LDH activity, that the model-free approach to measuring enzyme flux with the lactate-to-pyruvate ratio correlates with the concentration of active enzyme. Furthermore, in contrast to prior studies using FX11-which does not effectively target all isoforms of LDH-this application produced near-complete suppression of intratumoral lactate production.…”

“…We have previously validated our sequence parameters to resolve pyruvate's metabolites. 19,26 In the described experimental setup, we have not observed bicarbonate generation, including after suppression of LDH activity.…”

Efficient Parahydrogen Induced 13C Hyperpolarization on a Microfluidic Device

“…Hyperpolarized metabolites have great potential as contrast agents for magnetic resonance imaging (MRI) and magnetic resonance spectroscopic imaging (MRSI), providing real-time and quantitative information on active metabolic pathways in healthy and diseased tissues. 20,21 This approach has been used in vivo for metabolic profiling of tumours such glioma, 22,23 hepatocellular carcinoma, lymphoma, 24,25 pancreatic 26 and breast cancers. 27,28 In this modality, relatively large amounts (several g) of hyperpolarized material (most commonly pyruvate) are prepared and injected intravenously into the patient.…”

Efficient Parahydrogen Induced 13C Hyperpolarization on a Microfluidic Device

“…This allows provision of real-time and quantitative information on the kinetics of downstream metabolites in healthy and diseased systems. The method has been used in vivo for metabolic profiling of tumours such glioma, 12,13 hepatocellular carcinoma, lymphoma, 14,15 pancreatic 16 and breast cancers. 17,18 More generally, high-resolution NMR spectroscopy is an ideal technique to follow chemical reactions and monitor biological systems in LoC and OoC due to its non-invasive nature, chemical specificity and the ability to quantify metabolites.…”