TY - JOUR
T1 - In vivo characterization of platinum (II)-based linker technology for the development of antibody-drug conjugates
T2 - Taking advantage of dual labeling with 195mPt and 89Zr
AU - Muns, Joey A.
AU - Montserrat, Veronica
AU - Houthoff, Hendrik Jan
AU - Codée-Van Der Schilden, Karlijn
AU - Zwaagstra, Oene
AU - Sijbrandi, Niels J.
AU - Merkul, Eugen
AU - Van Dongen, Guus A.M.S.
PY - 2018/7/1
Y1 - 2018/7/1
N2 - Linker instability and impaired tumor targeting can affect the tolerability and efficacy of antibody-drug conjugates (ADCs). To improve these ADC characteristics, we recently described the use of a metal-organic linker, [ethylenediamineplatinum(II)]21, herein called Lx. Initial therapy studies in xenograft-bearing mice revealed that trastuzumab-Lx-auristatin F (AF) outperformed its maleimide benchmark trastuzumab-mal-AF and the Food and Drug Administration- approved ado-trastuzumab emtansine, both containing conventional linkers. In this study, we aimed to characterize Lx-based ADCs for in vivo stability and tumor targeting using 195mPt and 89Zr. Methods: The γ-emitter 195mPt was used to produce the radiolabeled Lx [195mPt]Lx. 89Zr-Desferrioxamine (89Zr-DFO) was conjugated to trastuzumab either via [195mPt]Lx (to histidine residues) or conventionally (to lysine residues) in order to monitor the biodistribution of antibody, payload, and linker separately. Linker stability was determined by evaluating the following ADCs for biodistribution in NCI-N87 xenograft-bearing nude mice 72 h after injection: Trastuzumab-[195mPt]Lx-DFO-89Zr, trastuzumab-[195mPt]Lx- AF, and 89Zr-DFO-(Lys)trastuzumab (control), all having drug-toantibody ratios (DARs) of 2.2-2.5. To assess the influence of DAR on biodistribution, 89Zr-DFO-(Lys)trastuzumab-Lx-AF with an AF-to-antibody ratio of 0, 2.6, or 5.2 was evaluated 96 h after injection. Results: Similar biodistributions were observed for trastuzumab-[195mPt]Lx-DFO-89Zr, trastuzumab-[195mPt]Lx-AF, and 89Zr-DFO-(Lys)trastuzumab irrespective of the isotope used for biodistribution assessment. The fact that Lx follows the antibody biodistribution indicates that the payload-Lx bond is stable in vivo. Uptake of the 3 conjugates, as percentage injected dose (%ID) per gram of tissue, was about 30 %ID/g in tumor tissue but less than 10 % ID/g in most healthy tissues. Trastuzumab-[195mPt]Lx-AF (DAR 2.2) showed a tendency toward faster blood clearance and an elevated liver uptake, which increased significantly to 28.1 ± 4.2 %ID/g at a higher DAR of 5.2, as revealed from the biodistribution and PET imaging studies. Conclusion: As shown by 195mPt/89Zr labeling, ADCs containing the Lx linker are stable in vivo. In the case of trastuzumab-Lx-AF (DARs 2.2 and 2.6), an unimpaired biodistribution was demonstrated.
AB - Linker instability and impaired tumor targeting can affect the tolerability and efficacy of antibody-drug conjugates (ADCs). To improve these ADC characteristics, we recently described the use of a metal-organic linker, [ethylenediamineplatinum(II)]21, herein called Lx. Initial therapy studies in xenograft-bearing mice revealed that trastuzumab-Lx-auristatin F (AF) outperformed its maleimide benchmark trastuzumab-mal-AF and the Food and Drug Administration- approved ado-trastuzumab emtansine, both containing conventional linkers. In this study, we aimed to characterize Lx-based ADCs for in vivo stability and tumor targeting using 195mPt and 89Zr. Methods: The γ-emitter 195mPt was used to produce the radiolabeled Lx [195mPt]Lx. 89Zr-Desferrioxamine (89Zr-DFO) was conjugated to trastuzumab either via [195mPt]Lx (to histidine residues) or conventionally (to lysine residues) in order to monitor the biodistribution of antibody, payload, and linker separately. Linker stability was determined by evaluating the following ADCs for biodistribution in NCI-N87 xenograft-bearing nude mice 72 h after injection: Trastuzumab-[195mPt]Lx-DFO-89Zr, trastuzumab-[195mPt]Lx- AF, and 89Zr-DFO-(Lys)trastuzumab (control), all having drug-toantibody ratios (DARs) of 2.2-2.5. To assess the influence of DAR on biodistribution, 89Zr-DFO-(Lys)trastuzumab-Lx-AF with an AF-to-antibody ratio of 0, 2.6, or 5.2 was evaluated 96 h after injection. Results: Similar biodistributions were observed for trastuzumab-[195mPt]Lx-DFO-89Zr, trastuzumab-[195mPt]Lx-AF, and 89Zr-DFO-(Lys)trastuzumab irrespective of the isotope used for biodistribution assessment. The fact that Lx follows the antibody biodistribution indicates that the payload-Lx bond is stable in vivo. Uptake of the 3 conjugates, as percentage injected dose (%ID) per gram of tissue, was about 30 %ID/g in tumor tissue but less than 10 % ID/g in most healthy tissues. Trastuzumab-[195mPt]Lx-AF (DAR 2.2) showed a tendency toward faster blood clearance and an elevated liver uptake, which increased significantly to 28.1 ± 4.2 %ID/g at a higher DAR of 5.2, as revealed from the biodistribution and PET imaging studies. Conclusion: As shown by 195mPt/89Zr labeling, ADCs containing the Lx linker are stable in vivo. In the case of trastuzumab-Lx-AF (DARs 2.2 and 2.6), an unimpaired biodistribution was demonstrated.
KW - ADC radiolabeling
KW - Antibody-drug conjugates
KW - Lx linker
KW - Pt
KW - Zr
UR - http://www.scopus.com/inward/record.url?scp=85049402989&partnerID=8YFLogxK
U2 - https://doi.org/10.2967/jnumed.117.206672
DO - https://doi.org/10.2967/jnumed.117.206672
M3 - Article
C2 - 29496986
SN - 0161-5505
VL - 59
SP - 1146
EP - 1151
JO - Journal of nuclear medicine
JF - Journal of nuclear medicine
IS - 7
ER -