1. ImmunoPET helps predicting the efficacy of antibody-drug conjugates targeting TENB2 and STEAP1.
- Author
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Williams SP, Ogasawara A, Tinianow JN, Flores JE, Kan D, Lau J, Go M, Vanderbilt AN, Gill HS, Miao L, Goldsmith J, Rubinfeld B, Mao W, Firestein R, Yu SF, Marik J, and Terwisscha van Scheltinga AG
- Subjects
- Animals, Antibodies, Monoclonal pharmacology, Antigens, Neoplasm, Antineoplastic Agents pharmacology, Humans, Male, Membrane Proteins antagonists & inhibitors, Mice, Molecular Targeted Therapy, Neoplasm Proteins antagonists & inhibitors, Oligopeptides pharmacology, Oxidoreductases antagonists & inhibitors, Prostatic Neoplasms drug therapy, Radioisotopes, Xenograft Model Antitumor Assays, Zirconium, Immunoconjugates pharmacology, Positron-Emission Tomography methods, Prostatic Neoplasms diagnostic imaging
- Abstract
The efficacy of antibody-drug conjugates (ADCs) targeted to solid tumors depends on biological processes that are hard to monitor in vivo. 89Zr-immunoPET of the ADC antibodies could help understand the performance of ADCs in the clinic by confirming the necessary penetration, binding, and internalization. This work studied monomethyl auristatin E (MMAE) ADCs against two targets in metastatic castration-resistant prostate cancer, TENB2 and STEAP1, in four patient-derived tumor models (LuCaP35V, LuCaP70, LuCaP77, LuCaP96.1). Three aspects of ADC biology were measured and compared: efficacy was measured in tumor growth inhibition studies; target expression was measured by immunohistochemistry and flow cytometry; and tumor antibody uptake was measured with 111In-mAbs and gamma counting or with 89Zr-immunoPET. Within each model, the mAb with the highest tumor uptake showed the greatest potency as an ADC. Sensitivity between models varied, with the LuCaP77 model showing weak efficacy despite high target expression and high antibody uptake. Ex vivo analysis confirmed the in vivo results, showing a correlation between expression, uptake and ADC efficacy. We conclude that 89Zr-immunoPET data can demonstrate which ADC candidates achieve the penetration, binding, and internalization necessary for efficacy in tumors sensitive to the toxic payload., Competing Interests: All authors are former or current employees of Genentech.
- Published
- 2016
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