Illustrations of Targeted Immunotherapy for Solid Malignancies

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Illustrations of Targeted Immunotherapy for Solid
Malignancies
Stephen Chia, MD, FRCP(C) Medical
Oncologist British Columbia Cancer Agency -
Vancouver Cancer Centre
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Goals

• History of skepticism
• Definitions with clinical illustrations
• Principles of immunotherapy
• Limitations of immunotherapy

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History of Skepticism

• Hewitt HB, et al. Br J Cancer 197633241
• in 27 different spontaneous tumors in mice no
  evidence of any immune response
• applicability of transplanted murine models
• Woglom WH. Cancer Res 19294129
• it would be as difficult to reject the right
  ear and leave the left ear intact as it is to
  immunize against cancer

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Classification of Immunotherapy

• Passive Immunotherapy
• immune based therapies with abilities to
  mediate anti-tumor response directly or
  indirectly
• antibodies trastuzumab, C225
• alone or conjugated (toxins, radiolabels)
• cells (adoptive) tumor infiltrating
  lymphocytes

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Classification of Immunotherapy

• Active Immunotherapy
• therapies designed to elicit a host immune
  response capable of eliminating or retarding
  tumor growth
• non-specific interferon, interleukin-2
• specific tumor antigen vaccines

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Principles of Immunotherapy

• Intact cell-mediated immunity
• Low tumor burden
• Immunogenic tumor

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Passive Immunotherapy Antibodies

• trastuzumab is a chimeric (95 human) monoclonal
  antibody directed against the extra-cellular
  domain of the HER-2/neu receptor
• HER2 overexpressed in 20 of breast cancers
  (ovarian, gastric cancer, NSCLC)
• prognostic and predictive value in breast cancer

Extracellular domain (632 amino
acids) Ligand-binding site
Transmembrane domain (22 amino acids)
Intracellular domain (580 amino acids) Tyrosine
kinase activity
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Trastuzumab in Combination with Chemotherapy in
Advanced Breast Cancer

• Slamon DJ, et al. N Engl J Med 2001344783-92
• combination of Herceptin chemotherapy superior
  to chemotherapy alone in
• RR 50 vs 32
• TTP 7.4 m vs 4.6 m
• OS 25.1 m vs 20.3 m
• N.B. 65 of chemo alone arm eventually received
  Herceptin

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Single agent Trastuzumab in Advanced Breast Cancer

• Vogel et al. J Clin Oncol 200220719-726
• phase II study of 114 MBC (HER2) of weekly
  trastuzumab
• RR 26 overall
• HER2 3 35
• HER2 2 0
• TTP 3.5 m

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Mechanism of Action Trastuzumab

• Cell cycle arrest (induction of p27 KIP1)
• Reduces metastatic potential (restores E-cadherin
  and ?2 integrin levels)
• Anti-angiogenic (reduces VEGF levels)
• Receptor down-modulation
• Complement dependent cytotoxicity
• Antibody dependent cell mediated cytotoxicity
  (ADCC)

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Mechanism of Action Monoclonal Antibodies

• Yin and Yang
• Fc?RIII is the activated
• Fc receptor on NK, mast cell and macrophages
• Fc?RIIB when activated inhibits Fc?RIII and
  thus down regulates immunity (macrophages not NK
  cells)

Adapted from Houghton AN, et al. Nature Med
20006373
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Passive Immunotherapy Antibodies

• Clynes RA, et al. Nature Med 20006443
• syngenic and xenograft models of mice deficient
  in Fc?RIII (activation) or Fc?RIIB (inhibitions)
• assessed in vivo effects of monoclonal
  antibodies (4D5, trastuzumab, rituximab)
• demonstrated lack of Fc?RIII abrogated efficacy
  of mAb

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Passive Immunotherapy Antibodies

• Clynes RA, et al. Nature Med 20006443
• demonstrated presence of Fc?RIIB abrogated
  efficacy of mAb
• elimination of Fc?RIIB restores efficacy of mAb

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2C4 disrupts ligand-dependent HER2 signaling
HER2
Low- affinity receptor
High- affinity receptor
Ligand-activated hetero-oligomer
Ligand
ATP
ADP
HERX
Akita R
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Effect of rhuMAb 2C4 or Herceptin on the growth
of human breast cancer cells (1 HER2 expression)
6,500 5,125 3,750 2,375 1,000
rhuMAb 2C4 Herceptin
RFU
IC50 120ng/mL 0.8nM
1 10 100 1,000 10,000
MAb (ng/mL)
3 day assay (Alamar Blue)
Totpal K
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AntibodyDrug Internalization
Receptor recycling
Early endosome
Ligand and receptor degradation
Ligand degradation
Lysosome
Low pH endosome
Nucleus
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Maytansinoids

• Natural products originally isolated from the
  East African shrub, Maytenus ovatus
• Now produced by microbial fermentation (Nocardia)
• Inhibits tubulin polymerization, similar to the
  vinca alkaloids

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Maytansinoids
O
O
CH3
H
O
N
S
S
lys-MAb
CH3
H3C
CI
CH3
O
O
H
O
H3CO
CH3
N
H3C
O
N
O
OH
CH3O
CH3
DM1
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In-vitro potency of DM1
100 80 60 40 20 0
Cisplatin VP-16 5-FU DM1 Doxorubicin
Survival ()
COLO 205 cells
1013 1012 1011 1010 109 108 107 106 105
104 103
Concentration (M)
Chari R, ImmunoGen
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MCF7HER2 xenograft (Herceptin-responsive model)
Herceptin, 10mg/kg, twice/week Herceptin-DM1,
300µg DM1/kg, days 15 Control MAb, 10mg/kg,
twice/week
3,200 2,800 2,400 2,000 1,600 1,200 800 400 0
Tumour volume (mm3)
0 4 8 12 16 20 24 28
Days
Dugger D, Schwall R
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Active Non-specific ImmunotherapyMetastatic
Renal Cell Carcinoma

• Rosenberg SA, et al. Ann Surg 199822307-19
• 409 consecutive metastatic melanoma or renal
  cell carcinoma
• treated with high dose IL-2 (720,000 IU/kg iv
  q8h for 5 days
• 8 CR and 9 PR
• 27/33 (82) maintained CR (39-148 m)
• IL-2 not cytotoxic in vitro
• in vivo IL-2 activate and expand lymphocytes

Adapted from Rosenberg SA. Nature 2001411380-4
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Active Specific ImmunotherapyAdjuvant Colon
Cancer

• Vermorken JB, et al. Lancet 1999353345-50
• prospective randomized trial 254 stage II and III
  to adjuvant ASI or no adjuvant therapy
• 2 autologous tumor cell vaccinations (107 viable
  irradiated cells) with 107 fresh frozen BCG q2w x
  2 followed by booster at 3 weeks and 6 months
  later
• 5.3 year median F/U
• improvement in recurrence free interval (p0.023)
• impact seen only in stage II

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Active Specific ImmunotherapyAdjuvant Colon
Cancer
Adapted from Vermorken JB, et al. Lancet
1999353345-50
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Limitations of Immunotherapy

• Low tumor burden
• tumor cells Mouse model Clinical setting
• 106 prophylaxis experiments
  clinically undetectable
• 107 therapy experiments clinically
  undetectable
• 108 therapy experiment clinically
  undetectable
• 109 rarely curable 1.5 cm mass
• 1010 beyond range testing advanced
  metastases
• 1011 beyond range testing terminally ill

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Active Specific Immunotherapy Metastatic
Melanoma

• Belli F, et al. J Clin Oncol 2002204169-80
• 42 patients metastatic melanoma
• autologous tumor derived heat shock protein
• (gp 96)-peptide complex (HSPPC-96)
• weekly immunizations x 4 (n39), then q2w x 4
  (n21) then monthly x 3 (n4)
• no treatment related toxicity
• 2/28 CR (559 and 703 days)
• 3/28 stable disease (153-272 days)

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Active Specific Immunotherapy Metastatic Melanoma

• Belli F, et al. J Clin Oncol 2002204169-80
• Principle of immunogenic tumor
• Immunopathology of resected metastases
• 7/8 clinical responders had high expression of
  HLA class 1(? 70 positive cells) and
  Melan-A/MART1or gp100
• 7/12 non-responders down-regulation of class
  1HLA (? 20 positive cells)

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Conclusions

• Renewed enthusiasm for immunotherapy as cancer
  treatment
• Abundance of clinical trials underway
• Early results do suggest suggest proof of
  principle of some efficacy
• Limitations exist as to the wide spread
  applicability across solid tumors and stages