ADC are an emerging class of new anti-cancer agents. They are the future of oncological management. Discussed here are their past, present and probable future.

1. Antibody-Drug Conjugates:
Current Status and Future Perspective
Presenter: Dr. Pranav Sopory
Junior Resident, MD Pharmacology
All India Institute of Medical Sciences
New Delhi
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2. Contents
Introduction
Conventional Cytotoxic Drugs: Side effects due to non-specificity
Monoclonal antibodies: Production, nomenclature and uses
Antibody-Drug Conjugates
Structure and mechanism of action
Current status of ADCs
Future perspectives
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3. Anti-Cancer Drugs
1. CYTOTOXIC DRUGS
Class Examples
Alkylating agents Mechlormethamine, Mitomycin, Melphalan, Cyclophosphomide,
Ifosphomide, Procarbazine, Nitrosourea, Busulfan
Platinum compounds Cisplatin, Carboplatin, Oxaliplatin
Anti-metabolites (S) DHFR#: Methotrexate, Pemetrexate.
Purine Analogues: 6-MP, 6-TG, Cladaribine, Fludaribine.
Pyrimidine Analogue: 5-FU, Capecitabine, Gemcitabine, Cytarabine.
Microtubule damaging agent (M) Formation#: Vincristine, Vinblastine
Breakdown#: Paclitaxel, Docetaxel
Topoisomerase-1 inhibitors Topotecan, Irenotecan
Topoisomerase-2 inhibitors Etoposide, Doxorubicin, Daunorubicin
Antibiotics Bleomycin, L-Asparginase,.
Miscellaneous Arsenic Trioxide, Thalidomide
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4. Cytotoxic Drugs: Side Effects
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• Bone Marrow
• Appetite
• Oral
• CNS
• PNS
• Renal
• Sterility

5. Monoclonal antibodies
mAb:
• Identical antibodies: clones of a single parent cell
• Are directed against a specific epitope
• Are produced by B-cell clones of a single parent or a single hybridoma cell
line
A hybridoma cell line
• is formed by the fusion of one B-cell lymphocyte with a myeloma cell.
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6. mAb: Production
B Cell
• Ig* (+)
• HGPRT* +
• Mortal
Myeloma Cells
• Ig (–)
• HGPRT (–)
• Immortal
Fusion of these cells via P.I.L.E* Techniques
Grown in a HAT medium
Myeloma cells die out due to Aminopterin | B Cells have a short lifespan
Only hybrid cells remain: Ig(+), HGPRT (+), Immortal
HYBRIDOMA TECHNIQUEIg: Immunoglobulin
HGPRT: Hypoxanthine Guanine Phosphoribosyl transferase
PILE: PEG, Inactivated Virus, Laser & Electricity
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7. mAb: Nomenclature
Palivizumab Abciximab Infliximab Denosumab Trastuzumab Bavituximab
Prefix Target substem Source substem Stem
Variable
-vi- Virus -a- rat
-mab
-ci- Circulation -e- hamster
-li- Immune
system
-i- primate
-so- Bone -o- mouse
-tu- Tumor -u- human
-tox- Toxin -xi- chimeric
-zu- humanized
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8. mAB: Structure
MOA:
1. Downregulation
2. ADCC*
3. CDC*
4. Phagocytosis
*ADCC: Antibody Dependent Cell Cytotoxicity
*CDC: Complemet Dependent Cytotoxicity
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9. mAB: Disadvantages
1. Anaphylaxis
Non-human component
Gomuliximab withdrawn from Asthma treatment
2. Resistance
P glycoprotein efflux
Receptor polymorphism
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10. Antibody Drug Conjugates (ADCs)
• Emerging model of anti-cancer treatment
• Combines:
1. Selectivity of targeted treatment
2. Cytotoxic potency of anti-cancer agents
• Increased Therapeutic Window
• T.W. = MEC / MTC
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11. ADC: Structure
LINKER Cytotoxic
Drug
• Targets a well- characterized
antigen Maintains specificity
and internalization when
attached to a cytotoxin
• Highly potent• Stable in circulation
• Selective intracellular release
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12. 1. Target Antigen
1. Limited Heterogeneity
2. High rate of expression
3. MAS*
4. Downregulation after internalization
5. Shared by TICs*
*MAS: Minimal Antigen Shedding
*TICS: Tumor Initiating Cells 12

13. 2. Antibody Selection
1. Humanized/ Fully Human Ab
Early generation: murine component
2. Preferably IgG1 component
3. Should retain ADCC and CDC
4. Downregulation
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14. 3. Linker
1. Stable
2. Devoid of pharmacological action
3. Site specific conjugation
4. Optimal DAR (Drug Antibody Ratio)
5. Three types
• Non-cleavable
• Cleavable
• Glutathione sensitive
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15. 4. Cytotoxic Payload
• Def: Percentage of administered drug reaching the tumor cells
• Usually 1-2 % for conventional cytotoxics
Cause of failure when used with Doxorubicin or MTX
• ADC: Chemotherapy should be extremely potent, being effective at
picomolar or nanomolar concentrations
• Newer agents used in ADC
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16. 4. Cytotoxic Payload: Newer agents
Maytansinoids:
Tubulin inhibitor
Used in Trastuzumab Emtansine
(T-DM1)
IC50: 10-11 to 10-9 M
Auristatins:
Tubulin inhibitor
M/C used payload in all ADCs
Used in Brentuximab Vendotin
Calicheamycin
Anti-tumor antibiotic
Used in Gentuzumab Ozagamicin
Others:
Duacarmycin: Alkylating agent
Alpha Amantin: RNA polymerase inhibitor
SN 38: Active metabolite of Irinotecan
Radio-immuno conjugates: Yittrium 90,
Iodine 131
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17. Timeline of ADC
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18. T-DM1: Trastuzumab Emtansine (Kadcyla)
• Components:
1. Trastuzumab: Anti-HER-2 Humanized IgG1 Ab
2. Non Cleaveable linker
3. Maytanisoid (DM1)
• Currently, FDA approved (2013) for:
2nd line HER-2 +ve MBC patients previously treated
with Trastuzumab or Taxane therapy
LINKER
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19. T-DM1: Trastuzumab Emtansine (Kadcyla)
• HER-2 neu +ve Breast Cancer
• Human Epidermal Growth Factor Receptor- 2
• Overexpression: Oncogenic
• 15-20% of all primary breast cancers
• Rx
1. Trastuzumab (Binds to EC sub-domain IV of HER-2)
2. Lapatinib (TKI)
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20. T-DM1: Mechanism of action
(endocytosis)
(attachment)
(proteolysis)
(DAR: 3.5)
Trastuzumab mediated effects:
Downregulation
ADCC
CDC
Phagocytosis
(resistance)
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21. T-DM1: Clinical Efficacy
3 year study
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22. T-DM1: Clinical Efficacy
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23. T-DM1: Clinical Efficacy
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24. T-DM1: Clinical Efficacy
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25. T-DM1
• Dose: 3.6 mg/kg given as an IV infusion.
• Duration of Rx: q 3 weeks (21-day cycle) until disease progression or unacceptable
toxicity
• t1/2: 4 days
• Side Effects:
1. Fatigue (46.4 percent)
2. Nausea (43 percent)
3. Thrombocytopenia(32.2 percent)
• Adverse Effects:
1. Hepatotoxicity: Acute Liver Failure
2. Cardiotoxicity (C/I: CHF)
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26. T-DM1: Future Status
1. Potential role as first line Rx for HER-2-neu +ve MBC
2. Combination with other therapies
3. Circumvent MDR 1 resistance
• PEG4Mal-DM1 metabolite evades MDR 1 drug resistance
4. Modulation of HER-2 recycling
• HSP-90 mediated
• Geldanamycin (# HSP-90): Increases I/C conc. of T-DM1
• T-DM1 is being investigated as a single agent in treatment of previously
treated Gastric carcinoma
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27. Rx guideline: Her-2-neu MBC
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28. Brentuximab Vedontin (Adcetris)
• Specifically targets CD 30 +ve cells
1. HD (Heterogenous)
2. ALCL (Homogenous)
• FDA approved (2011) for
1. Hodgkin’s Disease
• Relapsed, refractory CD 30 +ve HD following ASCT*
• Patients not eligible for ASCT who have failed 2 chemotherapy regimens
2. Anaplastic Large Cell Lymphoma
• Second line treatment
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*ASCT: Autologous Stem Cell Transplant

29. Adcetris
1. Components
• Anti-CD 30 Ab
• Cleavable linker
• MMAE (tubulin #)
2. Mechanism
a. Target localization
b. Endocytosis
c. Breakup
d. Action
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LINKER
cAC: Carnitine Acylcarnitine

30. Brentuximab Vedontin: Clinical Efficacy
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ORR: CR + PR
Hodgkin lymphoma (n = 102)
Systemic anaplastic large cell lymphoma (ALCL; n = 58)
Receiving brentuximab vedotin in phase II trials.
86%
74%

31. Brentuximab Vedontin
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• Dose: 1.8 mg/kg q 3 weekly
• Duration: Continue treatment until disease progression or unacceptable
toxicity.
• Contraindications:
Concomitant use with Bleomycin

32. Mylotarg (Gemtuzumab Ozogamicin)
• First ADC approved (accelerated*) in 2000 for AML patients>60 y.o.
who are not suitable candidates for conventional chemotherapy.
• Components:
1. Anti- CD33 IgG4 mAB (H’phillic)
2. Linker
3. Ozagamicin: Calicheamycin cytotoxin (H’phobic)
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33. Mylotarg (Gemtuzumab Ozogamicin)
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34. Withdrawal of Mylotarg (2010)
• Difficulty in linking small H’phillic mAb to large H’phobic cytotoxin
Conjugation required 20 % DMF (Di Methyl Formamide)
1. Helps maintain solubility of Hydrophobic payload
2. Promotes aggregation of mAB
• Also:
1. Drug showed good efficacy but poor effectiveness
2. Increased R/O thromboembolic disease
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35. Future perspective
1. Phase 1 clinical trials
2. Combination chemotherapy
3. Diagnostics with Radiolabeling
4. Combating Resistance
5. Cost
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36. Future perspective
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37. Thank You
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