Functional Optical Imaging of Primary Human Tumor Organoids: Development of a Personalized Drug Screen

Abstract

Primary tumor organoids are a robust model of individual human cancers and present a unique platform for patient-specific drug testing. Optical imaging is uniquely suited to assess organoid function and behavior because of its subcellular resolution, penetration depth through the entire organoid, and functional endpoints. Specifically, optical metabolic imaging (OMI) is highly sensitive to drug response in organoids, and OMI in tumor organoids correlates with primary tumor drug response. Therefore, an OMI organoid drug screen could enable accurate testing of drug response for individualized cancer treatment. The objective of this perspective is to introduce OMI and tumor organoids to a general audience in order to foster the adoption of these techniques in diverse clinical and laboratory settings.

Keywords: 3D culture; cancer drug screens; fluorescence imaging; multiphoton microscopy; optical; primary human spheroids.

FIGURE 1.

Clinical workflow of organoid-based anticancer drug screen.

FIGURE 2.

(A) Example fluorescence lifetime data (blue dots), system response (green line), and exponential decay fit (red line). Fluorescence lifetime decays, I(t), are often fit to 2-component exponential decay model, with mean lifetime (τ _m ) computed as weighted average of short and long lifetimes (τ ₁ and τ ₂) and proportion of short and long lifetimes (α ₁ and α ₂). χ² provides goodness-of-fit measure. At right are representative redox ratio image (B), NADH τ _m image (C), and FAD τ _m image (D) of organoid derived from human breast cancer biopsy. (Reprinted from (20).)

FIGURE 3.

OMI of primary (HER2-positive) human tumor organoids that develop resistance to paclitaxel chemotherapy over 72 h of treatment (upper row) and that respond to experimental drug cocktail of trastuzumab (anti-HER2) plus paclitaxel plus XL147 (lower row). A longer NADH mean lifetime, as evidenced by more red and orange tones, indicates resistance, whereas a shorter NADH mean lifetime, as evidenced by blue, indicates response. Scale bar is 100 μm.

FIGURE 4.

(A) NADH fluorescence lifetime image of organoid derived from HER2-positive human breast cancer biopsy sample demonstrates intraorganoid heterogeneity (reprinted from (20)). (B) Population modeling of representative organoid data, where blue bars are data and red lines are gaussian fits. (C) Population-density models of human-derived breast cancer organoids treated with control, trastuzumab plus paclitaxel plus XL147 (H+P+X), and trastuzumab plus paclitaxel plus tamoxifen plus XL147 (H+P+T+X). H+P+X-treated organoids demonstrate responding and nonresponding populations, whereas H+P+T+X-treated organoids demonstrate greater proportion of responding cells.