Cancer Vaccines

Gerald P. Linette, MD, PhDDivison of OncologySiteman Cancer CenterWashington University School of Medicine

April 17, 2002

Tumor Immunology lies at the intersection of 2 distinct (and complex) disciplines

Cancer Biology Immunology

Tumor Immunology

1. Cancer Vaccines2. Monoclonal Antibodies

Multiple cell-cell interactions influence anti-tumor immunity

- primary histology (lung vs melanoma vs lymphoma)

- local versus distant site

Why is there interest in cancer vaccines ?

• Vaccination against microbes is efficacious and saves lives. (NEJM 345:1042, 2001)

• Activation of the innate immune system can provide clinical benefit for select cancers. (Nature Immunology 2:293, 2001)

• Identification of tumor antigens. (Immunity 10: 281, 1999)

• New vaccination strategies. (Nature Med 4:525, 1998)

Today’s Discussion

• Historical Perspective

• Advances in basic immunology

• Tumor rejection antigens: do they truly exist?

• Immunization strategies: can we generate sustained (antigen-specific) immunity against tumors?

Old, 1996

Noble Prizes in Immunology: Impact on Tumor Immunology

1980 Benacerraf, Dausset, and Snell (immunogenetics)

1984 Milstein, Kohler, and Jerne (monoclonal antibodies)

1987 Tonegawa (antibody diversity)

1996 Doherty and Zinkernagel (MHC restriction)

II. Recent advances in basic immunology

• Innate immune system

• Precise monitoring of T cell immunity and the emerging model of T cell homeostasis

• Tolerance as the essential determinant of anti-tumor immunity

Innate Immune System: Toll-like receptors allow pattern recognition of microbes

TMHC IIpeptide

Immune monitoring: tetramer staining can quantitate antigen-specific CD8+ T cells

MHC class I

BAL fluid from Influenza virus

infected mice

Avidin-PE

T Cell Homeostasis: 3 distinct phases

R. Ahmed

T cell frequencies in various disease states

Tumors

EBV infectionInfluenza infection

Hepatitis virus

P Klenerman et al., 2002

Immunologic response depends on the contextof initial antigen-presentation

1. Activation

-mature DC-pro-inflammatory -2o lymphoid tissue

2. Tolerance

-immature DC or other APC-non-inflammatory-non lymphoid tissue

D. Pardoll

Additionalmechanisms oftolerance

MJ Smyth et al, 2001

Other variables that influence tolerance

• age

• co-morbid illness

• medications

• tumor burden

III. Tumor rejection antigens: Do they really exist?

• unique mutated (host-specific)

» p68 helicase

• shared mutated (tumor-specific)» ras

• shared non-mutated (cancer-testis)» MAGE family

• shared non-mutated (lineage-restricted)» gp100/tyrosinase/MART1

JNCI 18:769, 1957

Tumor-rejection antigensare unique and not shared.

What is the antigen?

Tumor-specific CD8+ CTL recognize a somatic mutation in p68 helicase (JEM 185:695, 1997)

Tumor - - - - - - - - - - - - - T - - - - - - - - - -GL AGT AAT TTT GTA TCT GCT GGC ATAProtein S N F V S/F A G I

UV-induced mutation (C->T) at nt1812 generates a unique,mutated protein that is specific for this host. P5 residue is nowan anchor residue for Kb class I molecule. Is this a true tumorrejection antigen?

HPLCMass Spec

Synthetic peptides

Ras is frequently mutated in human tumors

Position 12 or 61mutated: gain of function

Tumor % mutationpancreas 90colon 40liver 30

Mage Family - discovered in 1991- silent in normal tissues except testis and placenta- expressed in tumors of various histologies- 13 subfamilies with 55 genes- function is unknown

Chomez et al., 2001

Vaccine Design

• whole cell• protein (includes

DNA)• peptide

• conventional (alum, emulsions, microbial products, liposomes)

• cytokines• dendritic cells• blockade of negative

regulatory molecules

Antigen + Adjuvant = VACCINE

Current Cancer Vaccine Studies in Patients

156 clinical vaccine trials are currently openin the US

clinical trials.gov (April 16, 2002)

IV. Immunization Strategies: Can we generate sustained antigen-specific immunity?

• Dendritic cells as adjuvants (Mayordomo)

• Blockade of negative regulatory cell surface molecules and depletion of Treg cells (Sutmuller)

Pre-clinical studies

Therapeutic immunization for established tumors

3LL carcinoma model

0

50

100

150

200

0 7 14 21 28 35

days

mea

n tu

mor

siz

e (m

m2)

control

MUT1/DC

0

10

20

30

40

50

11 33 100

Effector:target ratio

DC/Mut1

DC/control

Mayordomo et al. 1995, Nature Med.

In vitro cytotoxicity assay

Tumor burden influences response to immunization

0

20

40

60

80

100

7 14 21 28

Per

cent

tu m

or-f

ree

Start of DC immunization (days post-tumor graft)

Therapeutic Immunization

-Peptide antigen

-DC hyper-immunization

-minimal tumor burden

Depletion of CD25+ Treg prior to vaccination promotes the rejection of melanoma in tumor bearing mice

Day: -4 0 0,3,6

Anti-CD25 mAb B16/GM-CSF VAX given sc

Anti-CTLA4 mAb

Irradiated B16/GM-CSF melanoma vaccine

Survival

NO CD25

Vax+CTLA4

Vax+CD25

Vax+CD25+CTLA4Vax+CD25+CTLA4

Vax+CTLA4

CD25

Vax alone is ineffective

Sutmuller, JEM 2001

Therapeutic efficacy correlates with increased frequency of antigen-specific CTL

Tetramer analysis Intracellular staining

*

*

*

Clinical studies

• Peptide with dendritic cells as adjuvants in melanoma vaccine (Nestle)

• idiotype protein with GM-CSF as adjuvant in lymphoma vaccine (Bendandi)

Dendritic cell vaccination in humans

F Nestle et al, 2001

Vaccination of melanoma patients with peptide- or tumor lysate-pulsed dendritic cells

F.O. Nestle et al. Nature Med 4:328, 1998

• Phase I clinical trial (n=16) in stage 4 melanoma using autologous DC.

• Patients were immunized with 1x106 DC by direct injection into an uninvolved lymph node qweek x6.

• 5 objective responses were recorded (2CR, 3PR) by week 10. Immunological reactivity to melanoma antigens was documented in 11 patients.

• Treatment was safe, well-tolerated and feasible.

year # enrolled #CR #PR RR(%) DC source antigen author1998 16 2 3 31% monocyte peptide or lysate Nestle2000 11 0 0 0 monocyte mage peptide Thurner2000 14 0 0 0 HSC peptides Mackensen2000 10 0 1 10 monocyte modified peptide Panelli2000 16 1 0 6 monocyte modified peptide Lau2001 12 1 1 17 monocyte modified peptide Linette2001 11 0 0 0 Mo vs HSC peptide Jonulett2001 2 0 0 0 monocyte peptide Andersen2001 23 0 0 0 monocyte peptide Toungouz2001 18 3 2 25 HSC peptide Banchereau2002 22 1 1 9 monocyte ad/gp100 and Mart1 Linette

TOTAL 155 8 8 10

Clinical Trials for Melanoma: First Generation Dendritic Cell Vaccines

Idiotype serves as a tumor antigen

Complete molecular remissions induced by patient-specific vaccination plus GM-CSF

against lymphomaM Bendandi et al. Nature Med 5:1171, 1999

• Phase I/II clinical trial (n=20) in low-grade, stage III/IV NHL who achieved CR after combination chemotherapy.

• Patients were immunized with Ig protein conjugated to KLH (beginning at 6 mo) q mo x 4

• Immunological reactivity was seen in 19/20 patients.

• 18/20 patients remain in first CR (median 42 mo; range 28-53+).

8 (of 11) patients had a molecular CR after vaccination

Summary

• Antigen identification and new vaccination strategies have been instrumental in advancing our knowledge of cancer vaccines.

• Vaccines for melanoma and lymphoma show encouraging results.

• Vaccines for other malignancies such as breast, colon, lung, and prostate carcinoma are in early stage clinical trials.

Summary

• Past: cancer vaccine clinical trials have been conducted in patients with advanced (metastatic) disease.

• Future: cancer vaccines will most likely be used as adjuvant therapy for patients with minimal or no measurable disease.