Tumour immunotherapy

Tumour Immunotherapy:Harnessing Immune Responses to Cancer

Dr Alasdair Fraser

Sylvia Aitken Research Fellow Section of Experimental Haematology,

Glasgow Royal Infirmary

Tumour Immunotherapy: possible?

“It would be as difficult to reject the right ear and leave the left ear intact, as it is to immunize against cancer.”

W.H.Woglom, Cancer Research (1929)

Tumour Immunotherapy: questions

• Can immune stimulators combat cancer?

• Which forms of immunotherapy can be used?

• Is vaccination effective against established tumours?

• Can anti-tumour responses be generated in vitro?

• Can in vitro responses translate into in vivo effects?

• What barriers are there to development of effective IT?

How can we harness the immune response?

Tumour cell present

Broken up to release antigens

APC

APC recruits T cells able to recognise tumour antigens

T

T

Th

CTL

CTL recognise and destroy other

tumour cells

CTL

Th cells educate other T/B cells

B

Ab / ADCC / cytokine attack

‘Passive’ immunotherapy

• Adminstration of monoclonal antibodies which target either tumour-specific or over-expressed antigens.

• Kill tumour cells in a variety of ways:

Apoptosis induction

Complement-mediated

cytotoxicity

ADCC

NKMØ

Conjugated to toxin / isotope

Antibody-based immunotherapy

Name Malignancy Target

Rituxan B cell lymphoma CD20

Herceptin Breast, lymphoma Her-2/neu

Campath B-CLL CD52

Erbitux Colo-rectal EGFR

Avastin Colo-rectal VEGF

Name Malignancy Target

Mylotarg AML CD33(calicheamicin)

Bexxar B cell lymphoma CD20(131In / 90Y)

Effects of antibody therapy

• Rituxan and Campath often used to control disease with fewer side-effects than chemotherapy.

• Herceptin is the only monoclonal which is effective against solid tumours.

• Immunotoxins still not commonly used due to problems with penetration and specificity.

• Bexxar trial in 2005 reported 59% of BCL disease-free 5 years after a single treatment.

‘Active’ immunotherapies

• Cytokines- IL-2 / IFNs / TNFα

• Vaccination strategies- single peptidemultiple peptides

HSP complexes whole tumour cells

• Cell-based therapies - tumour-specific CTLtumour-derived

APC DC priming

Complete regression of a large liver metastasis from kidney cancer in a patient treated with IL-2.

Regression is ongoing seven years later

Effective therapies

Rosenberg (2001) Nature, 411;381-4

Other Immunostimulants

• BCG (bacterial preparation) injected intra-tumour- Can be effective for early-stage bladder cancer.

• IFNα was ‘gold standard’ for CML until recent introduction of Gleevec (imatinib) – affects MHC Class I expression and cell division.

• TNFα effective in vitro, but too toxic to use in patients (pyrexia / -algias).

Peptide vaccines

•Single peptides:

Melanoma most thoroughly covered (Phase III).

bcr-abl fusion peptide trial underway.

Naked DNA prime-boost also trialled.

Tumour escape through selection of non-antigen variants selected.

•Multiple peptide vaccines

Microarray data identified new candidate Ags.

Breadth of IR correlates with improved survival.

Peptide vaccination

• Improved effects of vaccination when given with adjuvants (eg CpG).

• Immunostimulators also accentuate response (GM-CSF, IL-2, IL-12).

• Alternatively, can target inhibitory receptors to increase anti-tumour responses (αCTLA4).

Effectiveness of multiple antigen vaccines

Patient with multiple metastatic melanomas treated with tyrosinase / gp100 / MART vaccine

STRESSES

HSPs protect the delicate functions of the cell.

Heat Shock Proteins for Therapy

Heat Shock Proteins(HSP70)

NH4COOH

ATPase peptide-binding domain

tumour peptide sequence

How is the anti-tumour effect produced?

APC

TAP systemTransporter Associated with Peptide processingCD91

Hsp70 or gp96 / peptide complex

endocytosisreceptor

CTL

NK

tumour peptides presented to CTL / NK cells via HLA Class I

Survival rates in a model of lymphoma

Immunized with PBS ()

40 µg HSP70 from liver ()

20 µg HSP70 A20 cells ()

40 µg HSP70 A20 cells ()

Vaccination using HSP complexes

Peripheral blood from CML patient

Isolate HSP complexes from

tumour cellsDevelop DC

Co-culture with patient T cells and expand effectors

for infusion into patient

Load mdDC with HSP complexes in vitro

Immunize patient directly with tumour antigen-

primed mdDC

Using whole cells for immunization

• Killed tumour cells effective vaccinating agents in mouse models- not effective in humans.

• Novel methods can enhance immunogenicity of tumour cells.

CTL

tumour

tumour

tumourtumour

CTL

tumour

CTL

tumour

CTLCTL

CTL

Allogeneic Transplant-The Original Immunotherapy.

• Allogeneic bone marrow or stem cells – repopulate patient with entirely new immune system (matched to donor closely)

• Relatively crude- associated with significant morbidity / mortality

• Modification using T cell depletion or RISCT

relapse

Tumourtherapy

No Donor Available

MRD established

peptide vaccine (single Ag) HSP vaccine (multiple Ag) Ag-specific CTL leukaemic DCs ex-vivo Ag-primed DC IFNα/ IL-2

Development of resistance to therapy

Lasting remission / cure

Myeloablative alloSCT or RISCT

+ DLI

Matched allodonor

Quiescent tumour ‘stem’ cell

Proliferating tumour cells

?

Diagnosis

Copland et al (2005) Cancer Immunol. Immunother. 54:297

Dendritic cell therapy

• Dendritic cells are key components of the adaptive immune response

• APC function with ability to direct IR (activation/tolerance)

• Present in peripheral blood as circulating subtypes (<0.4% TWC)

Dendritic cell sources for therapy

Haemopoietic Stem Cell

Common Myeloid Progenitor

Monocyte

CirculatingMyeloid DC

Immature mdDC

Ex vivo GM-CSF + IL-

4

CD34+Stem Cell

CD34+ DC

Ex vivo GM-CSF +

Flt-3 + TNF

Mature mdDC

Maturation factors

Copland et al (2005) Cancer Immunol. Immunother. 54:297

DC-based therapy

DC developed from patient monocytes

Pulsed with target antigens

Stimulated to maturation and inoculated back into

patient

Tumour-specific immune responses

measured

Currently in Phase II and Phase III trials for melanoma, prostatic carcinoma and lymphoma.

Results of current clinical trials

• Wide variation in markers of response:

Evidence of IR through dth, CD4 prolifn., isolation of tumour-specific CTL in periphery and detection of TIL.

• How do these reflect true responses to therapy?

Peptide vaccine trials

175 patients total

7 patients responded

(4.0%)

Tumour vaccine trials

142 patients total

6 patients responded

(4.2%)

DC vaccine trials

257 patients total

16 patients responded

(6.2%)

Total for all cancer vaccine studies = 3.8%

Immunotherapy of cancer in action

•PTLD- Post-transplant lymphoproliferative disease

•Caused by EBV recrudescence during immuno-suppression.

•Current chemotherapy toxic.

•Novel immunotherapy approach applied-

Bank of EBV-specific T cell clones collected from dozens of blood donors, expanded and stored

(currently covers ~95% of all UK MHC haplotypes)

Effects of matched EBV-specific CTL therapy

Haque et al. J Immunol (1998). 160, 6204-6209

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Sample Timepoint

EB

V C

op

y N

um

ber

/Mill

ion

Cel

ls

EBV load after allogeneic CTL infusions

Defining whether malignancies are suitable for Immunotherapy

Chronic Myeloid Leukaemia

• High tumour burden

• Effective therapy (IM)

• Intact immune response

• Several candidate antigens identified

• Strong potential for IT approaches

Multiple Myeloma

• Low tumour burden

• Adequate therapies

• Impaired immune response

• Few candidate antigens identified

• Many factors (eg. age) reduce effectiveness of IT.