Since 2000, the research and development of precision therapy represented by small molecule targeted drugs and antibodies has made great progress and become the main targeted therapy for tumors. However, since small molecules and antibody drugs can specifically target tumor signaling pathways or antigens on the surface of tumor cells, and the heterogeneity between tumor cells is strong, precision therapy is very important for precision therapy. ADCs combine the dual advantages of small molecule and antibody drugs compared to antibody or small molecule drugs alone. Many ADCs have demonstrated impressive activity against treatment-refractory cancers, resulting in their approval for both hematologic malignancies and solid tumorindications.
After decades of research and troubleshooting, significant technological advancements and an improved mechanistic understanding of ADC activity culminated in the FDA approval of 14 ADCs, each providing demonstrable therapeutic benefit to cancer patients. Currently, about 297 ADCs are in preclinical/clinical development, indicating that the world is ushering in a new era of targeted cancer therapy.
|ADC||Common Name||Target||mAb||Linker||Payload||Payload Action||DAR||Conjugation||Company|
|Mylotarg||Gemtuzumab Ozogamicin||CD33||IgG4||Acid Cleavable||Ozogamicin/ Calicheamicin||DNA Cleavage||2-3||Lysine||Pfizer|
|Adcetris||Brentuximab Vedotin||CD30||IgG1||Enzyme Cleavable||MMAE/ Auristatin||Microtubule Inhibitor||4||Cys||Seattle|
|HER2||IgG1||Non-Cleavable||DM1/ Maytansinoid||Microtubule Inhibitor||3.5||Lysine||Roche|
|CD22||IgG4||Acid Cleavable||Ozogamicin/ Calicheamicin||DNA Cleavage||6||Lysine||Pfizer|
|CD79b||IgG1||Enzyme Cleavable||MMAE/ Auristatin||Microtubule Inhibitor||3.5||Cys||Roche|
|CD22||-||Enzyme Cleavable||Pseudomonas Exotoxin A||-||-||Cys||Astrazeneca|
|Nectin4||IgG1||Enzyme Cleavable||MMAE/ Auristatin||Microtubule Inhibitor||3.8||Cys||Seattle|
|Enhertu||Famtrastuzumab Deruxtecannxk||HER2||IgG1||Enzyme Cleavable||DXd/ Camptothecin||TOP1 Inhibitor||8||Cys||Daiichi Sankyo|
|TROP2||IgG1||Acid Cleavable||SN-38/ Camptothecin||TOP1 Inhibitor||7.6||Cys||Immunomedics|
|BCMA||IgG1||Non-Cleavable||MMAF/ Auristatin||Microtubule Inhibitor||4||Cys||GSK|
|CD19||IgG1||Enzyme Cleavable||SG3199/ PBD Dimer||DNA Cleavage||2.3||Cys||ADC Therapeutics|
|Akalux||Cetuximab Saratolacan||EGFR||-||-||-||-||-||Lysine||Rakuten Medical|
|Aidixi||Disitamab Vedotin||HER2||IgG1||Enzyme Cleavable||MMAE||Microtubule Inhibitor||4||Cys||RemeGen|
|Tivdak||Tisotumab Vedotintftv||Tissue Factor||IgG1||Enzyme Cleavable||MMAE/ Auristatin||Microtubule Inhibitor||4||Cys||Seagen|
Table 1. FDA approved ADCs currently on the market.
A typical antibody formulation contains ADC, excipients (sugars or salts), buffers, surfactants (Tween) and other metal ion chelators. Table 2 lists the formulations of 14 ADCs, which show that even with the same linker-payload, the final formulation buffer used by different antibodies will be different.
|Mylotarg||4.5mg||1mg/ml||5mM Phosphate||14mg Sucrose, 8mg Glucan 40, 5.2mg Sodium Chloride||-||7.4|
|Adcetris||50mg||5mg/ml||20mM Citrate||70mg Trehalose Dihydrate||0.2mg Tween80||6.6|
|Kadcyla||100mg, 160mg||20mg/ml||10mM Succinic acid||60mg Sucrose||0.2mg Tween80||5.0|
|Besponsa||1mg||0.25mg/ml||18mM Tromethamine||45mg Sucrose, 5.2mg Sodium Chloride||0.1mg Tween80||8.0|
|Lumoxiti||1mg||1mg/ml||25mM Phosphate||40mg Sucrose, 80mg Glycine||0.2mg Tween80||7.4|
|Polivy||140mg||20mg/ml||8mM Succinic Acid||40mg Sucrose||1mg Tween80||5.3|
|Padcev||23mg, 33mg||10mg/ml||20mM Histidine||55mg Trehalose Dihydrate||0.2mg Tween80||6.0|
|Enhertu||100mg||20mg/ml||25mM Histidine||90mg Sucrose||0.3mg Tween80||5.5|
|Trodelvy||180mg||10mg/ml||18mM MES||7.8mg Trehalose Dihydrate||0.1mg Tween80||6.5|
|Blenrep||100mg||50mg/ml||20mM Citrate||75.6mg Trehalose Dihydrate||0.2mg Tween80||6.2|
|Akalux||250mg||5mg/ml||10mM Sodium Phosphate||90mg Trehalose||0.2mg Tween80||7.1|
|Zynlonta||10mg||5mg/ml||20mM Histidine||59.9mg Sucrose||0.2mg Tween80||6.0|
|Aidixi||60mg||10mg/ml||10mM Histidine||43.72mg Mannitol, 20.54mg Sucrose||0.2mg Tween80||6.1|
|Tivdak||40mg||10mg/ml||30mM Histidine||30mg Mannitol, 30mg Sucrose||-||6.0|
Table 2. ADCs formulation analysis.
Among the 14 ADCs on the market, most ADCs have pH values between 6.0 and 6.9. Among them, histidine salt was the most important buffer type. Among the 14, 5 were histidine, 3 phosphate, 2 citrate, 2 succinate, 1 tromethamine and 1 MES. Generally, the selection of ADC buffer needs to follow the following principles: according to the buffer range of different buffer pairs, the pH gradient was set from 4.0-8.0 to prepare the ADC concentration for clinical use. Then, they were placed at 25°C and 40°C for 7 days, observed and sampled on day 0, day 1, day 3 and day 7, respectively, including observation of clarity, BCA detection concentration, SEC-HPLC detection of purity, DSC detection of thermal stability, etc.
When the suitable pH range is determined, two buffers at the pH can be selected. For example, when the suitable pH is 6.0, 30 mM histidine or 20 mM citric acid can be selected as the buffering agent of the preparation, and then the next step is screened.
|Mylotarg||5mM Phosphate||0.52mg disodium hydrogen phosphate anhydrous, 0.09mg sodium dihydrogen phosphate monohydrate||7.4|
|Adcetris||20mM Citrate||5.6mg sodium citrate dihydrate, 0.21mg citric acid monohydrate||6.6|
|Kadcyla||10mM Succinic Acid||-||5.0|
|Besponsa||18mM Tromethamine||2.15mg tromethamine||8.0|
|Lumoxiti||25mM Phosphate||3.4mg water sodium bicarbonate phosphate||7.4|
|Polivy||8mM Succinic Acid||1mg Succinic Acid||5.3|
|Padcev||20mM Histidine||1.40mg L-histidine, 2.31mg L-histidine hydrochloride||6.0|
|Enhertu||25mM Histidine||0.89mg L-histidine, 4.04mg L-histidine hydrochloride||5.5|
|Trodelvy||18mM MES||3.8mg MES||6.5|
|Blenrep||20mM Citrate||0.42mg citric acid, 6.7mg disodium and trisodium citrate dihydrate||6.2|
|Akalux||10mM Sodium Phosphate||-||7.1|
|Zynlonta||20mM Histidine||1.4mg L-histidine, 2.3mg L-histidine hydrochloride||6.0|
|Aidixi||10mM Histidine||2.1mg histidine hydrochloride (adjusted with NaOH)||6.1|
|Tivdak||30mM Histidine||2.11mg L-histidine, 3.44mg L-histidine hydrochloride||6.0|
Table 3. ADCs pH and buffer analysis.
Surfactants reduce aggregate production primarily by reducing surface tension. Of the 14 ADCs, 7 used 0.01-0.02% (W/V) Tween 80, 3 used 0.01-0.02% (W/V) Tween 20, and 1 used 0.03% Tween 80, 1 used 0.1% Tween 20, and the other 2 did not add surfactant. Generally, there are two screening principles for surfactants.
Among the 14 ADC formulations, various sugars or salts were added as excipients mainly. When setting different sugars and salts, there are many combinations and types. 10% trehalose, 9% sucrose, 5% sorbitol, etc. can be used as the basic formula for preliminary screening. When it is necessary to combine, the content of the two is halved. After 14 days of storage at 4°C, 25°C, and 40°C, characterizations were performed for transparency observation, BCA concentration detection, SEC-HPLC purity detection, DSC thermal stability detection, CIEF pH detection, etc.