Title: New bioorthogonal Raman tags as tools for preclinical oncology drug development
Funder: Cancer Research UK

Abstract: Oncology drug development is costly and ineffective with a 5% success rate from first-in-man studies to new drug registration. A task force set up to address issues in anticancer therapy development highlighted the necessity to demonstrate proof-of-mechanism and obtain information on key pharmacokinetic aspects of drug behaviour in preclinical and early clinical trials. Rapid advances in the field of Raman imaging, particularly in stimulated Raman scattering (SRS), offer the potential to transform our understanding of intracellular drug distribution and mechanism of action. • Raman is a non-destructive technique, employing relatively low energy laser irradiation allowing live cell imaging with fast acquisition speeds • Raman imaging allows species-specific label-free visualization without fixatives or stains • Emerging strategies in bioorthogonal chemistry target the “silent region” of the Raman spectra of cells providing dramatic enhancements in contrast and signal-to-noise ratios • SRS provides a quantitative readout (in contrast to more widely-used CARS and SERS techniques), allowing local intracellular concentrations to be determined • SRS provides high spatial and temporal resolution enabling single cell pharmacokinetic measurements Analysis of FDA approved drugs identified only 5% that contain spectroscopically bioorthogonal Raman functional groups inherent to their structure. However, we have demonstrated the potential for biorthogonal chemistry tagging strategies to allow visualization of intracellular drug uptake. To fully realize the potential of this methodology novel chemistry approaches will be utilised to minimise the impact of tags on biological activity while maximizing their Raman activity. As a test platform we will develop Raman active analogues of the poly [ADP-ribose] polymerase (PARP) inhibitor olaparib and the WEE1 inhibitor AZD1775. Although olaparib is currently used for the treatment of ovarian cancer, further understanding of resistance mechanisms and possible synergism with other targeted agents, including AZD1775, would help increase the potential number of patients who would benefit from treatment. Quantitative SRS imaging of ovarian cancer cell line models (including those that are resistant to olaparib and AZD1775) will provide measurements of rates of individual drug uptake and localization to specific intracellular organelles. In combination with multiphoton imaging approaches, including the use of fluorescence reporters, this will allow intracellular drug concentrations to be mapped onto phenotypic outputs such as DNA damage and apoptosis. We will show how these approaches can then be applied to models of tumour imaging and how system modifications such as SRGOLD and adaptive optics, will further improve imaging sensitivity and resolution allowing imaging in mouse models.

Lay abstract: Oncology drug development is costly and ineffective with a 5% success rate from first-in-man studies to new drug registration. A task force set up to address issues in anticancer therapy development highlighted the necessity to demonstrate proof-of-mechanism and obtain information on key pharmacokinetic aspects of drug behaviour in preclinical and early clinical trials. Rapid advances in the field of Raman imaging, particularly in stimulated Raman scattering (SRS), offer the potential to transform our understanding of intracellular drug distribution and mechanism of action. • Raman is a non-destructive technique, employing relatively low energy laser irradiation allowing live cell imaging with fast acquisition speeds • Raman imaging allows species-specific label-free visualization without fixatives or stains • Emerging strategies in bioorthogonal chemistry target the “silent region” of the Raman spectra of cells providing dramatic enhancements in contrast and signal-to-noise ratios • SRS provides a quantitative readout (in contrast to more widely-used CARS and SERS techniques), allowing local intracellular concentrations to be determined • SRS provides high spatial and temporal resolution enabling single cell pharmacokinetic measurements Analysis of FDA approved drugs identified only 5% that contain spectroscopically bioorthogonal Raman functional groups inherent to their structure. However, we have demonstrated the potential for biorthogonal chemistry tagging strategies to allow visualization of intracellular drug uptake. To fully realize the potential of this methodology novel chemistry approaches will be utilised to minimise the impact of tags on biological activity while maximizing their Raman activity. As a test platform we will develop Raman active analogues of the poly [ADP-ribose] polymerase (PARP) inhibitor olaparib and the WEE1 inhibitor AZD1775. Although olaparib is currently used for the treatment of ovarian cancer, further understanding of resistance mechanisms and possible synergism with other targeted agents, including AZD1775, would help increase the potential number of patients who would benefit from treatment. Quantitative SRS imaging of ovarian cancer cell line models (including those that are resistant to olaparib and AZD1775) will provide measurements of rates of individual drug uptake and localization to specific intracellular organelles. In combination with multiphoton imaging approaches, including the use of fluorescence reporters, this will allow intracellular drug concentrations to be mapped onto phenotypic outputs such as DNA damage and apoptosis. We will show how these approaches can then be applied to models of tumour imaging and how system modifications such as SRGOLD and adaptive optics, will further improve imaging sensitivity and resolution allowing imaging in mouse models.

Research activity codes: 4.1 DISCOVERY AND PRECLINICAL TESTING OF MARKERS AND TECHNOLOGIES;5.1 PHARMACEUTICALS
Health categories: CANCER AND NEOPLASMS