Outline

1. The immune system, infection, and the prevention of cancer Epidemiological clues from transplant recipients and people with AIDSAndrew GrulichUNSW Medical Faculty Dean’s Lecture, September 2007 National Centre in HIV Epidemiology and Clinical Research, University of New South Wales, Sydney, Australia.

2. Outline • Background • The known role of infection in the causation of cancer • What can we learn from immune deficient populations? • Studies in transplant recipients • Studies in people with HIV/AIDS • Two examples • What causes Kaposi’s sarcoma? • What causes non-Hodgkin’s lymphoma? • Future directions and interventions

3. Established virus-cancer relationships aIn immune suppressed populations

4. Established virus-cancer relationships

5. Other infective agents and cancer

6. The magnitude of the effect Parkin et al, Int J Cancer, 2006

7. How does infection cause cancer? • Direct effects of virally-encoded proteins • HPV • E6 inactivates P53 by inducing rapid degradation • E7 activates cyclin dependent kinase 2 • HTLV1 • Tax transcriptionally activates a variety of oncogenes • EBV • LMP1 up-regulates BCL2 and a range of cellular oncogenes • Indirect effects • HBV/HCV • Not directly oncogenic • Carcinogenicity may depend on the immune response • H pylori and flukes • Not directly oncogenic • ?chronic inflammation

8. Summary: the role of infection • Infection is acknowledged as having an important role in the causation of cancer • Over the past 25 years, the proportion of all cancers thought to be infection-related has increased from around 5% to close to 20% • Discoveries have arisen mainly from the study of single agent-single cancer associations • What can the study of immune deficient populations add?

9. Immune deficient populations Impaired immunity can unmask the carcinogenic effects of infection

10. The interlinked effects of infection and immunity • The effects of infection and of impaired immunity are linked • Impaired immunity leads to increased clinical expression of infectious diseases • Increased replication of infective agents and • an increased risk of those cancers related to infection • The relationship may be more complex • when carcinogenesis depends on a robust immune response • eg liver cancer, stomach cancer • When the cancer arises from cells of the immune system • B lymphocytes (90% of lymphoma) • T lymphocytes • Others (rare)

11. Immunological surveillance: • “small accumulations of tumour cells may develop, and because of their possession of new antigenic potentialities, provoke an effective immunological reaction with regression of the tumour, and no clinical hint of its existence” • Cancer - a biological approach, 1957. Sir Frank Macfarlane Burnet Nobel Prize, 1960

12. Immune deficiency and cancer: history • 1950’s: immune surveillance theory • Immunity essential for the recognition and elimination of emerging cancer clones • Impaired immunity should result in increased risk of all cancer types • 1970: the advent of post-transplantation immune suppression • Increased rates of Kaposi’s sarcoma and NHL noted immediately • Little evidence of other increases • 1980: the advent of AIDS • Increased rates of Kaposi’s sarcoma and NHL noted immediately • Inconsistent evidence of other increases • 2000+: larger populations of people with HIV and transplant recipients • Are other cancers associated with immune deficiency? • Might these populations provide a way to allow new discoveries of infectious causes of cancer?

13. Study design: immune suppression and cancer How do we study whether cancer occurs at increased rates in people with immune deficiency? • Clinical cohort studies • Relatively expensive, of limited power thus far • “Linkage” studies • Link identifiers of people with HIV/AIDS, or transplant recipients, with cancer registers • Compare rates of cancer to those in the general population using the SIR • Where such databases exist, these effectively create a population-wide cohort study • Australia’s advantage • longstanding and nationwide HIV and transplant registration and cancer registration • A comparison of the pattern of cancer in transplant recipients with cancer in people with HIV/AIDS has the potential to help guide our thinking about which cancers we might expect to occur at increased risks in people with impaired immunity

14. Cancer in transplant recipients • By the year 2000, there was • General agreement that there are markedly increased rates of Kaposi’s sarcoma and non-Hodgkin lymphoma • A study from Sweden in the late 1990’s suggested a wider range of cancers occur at increased rates • There was a lack of agreement on which cancers occur at increased rates, and whether or not these might be related to factors which also caused end stage renal disease • New, potentially less carcinogenic compounds being trialled for use in immune suppression (m-TOR inhibitors)

15. Cancer in Australian kidney transplant recipients • Methods • Data linkage • Name-based, probabilistic • Retrospective population-wide cohort study, 1982-2002 • Data linkage between: • Australia and New Zealand Dialysis and Transplant Registry (ANZDATA) • Population-based register of renal transplantation, since 1960’s • Enter register at dialysis for end stage renal disease • National Death Index (NDI) • Population-based register of all deaths in Australia • National Cancer Statistics Clearing House (NCSCH) • Population-based register of cancers occurring nationally, since 1982

16. Methodology Study population

17. Results Cohort characteristics

18. Results: viruses Inconclusive evidence Sufficient evidence Limited evidence Vajdic et al, JAMA, 2006

19. Summary • Kidney transplantation is associated with increased cancer risk across a number of sites • For most of these, cancer risk was not increased prior to transplantation • Most, but not all, were cancers with a known or suspected viral cause • These data suggest an important role of the interaction between common viral infections and the immune system in the aetiology of a large variety of types of cancer

20. How does this compare to HIV? • NHL, KS and cervical cancer are recognised as part of the definition of AIDS • A variety of other cancers occur at increased rates in people with HIV • Anal Cancer (RR 40, only in gay men) • Leiomyosarcoma in children (RR > 50) • SCC of the conjunctiva (RR 10-20) • Hodgkin disease (RR about 10) • Lip cancer (RR at least 5) Grulich et al, AIDS, 1999; Engels et al, AIDS, 2006. • Based on the largest single study, the US AIDS-cancer match, these were not associated with immune deficiency • The authors concluded that lifestyle factors , and not immune deficiency, likely explain these increased risks Frisch et al, JAMA, 2001.

21. Are these cancers associated with i-deficiency? • US AIDS-cancer match • A cancer is judged as AIDS-related if • SIR increased for the entire period from 5 years before until 2 years after AIDS • Increasing trend of SIRS pre to post AIDS • Many cancers increased overall • few had an increasing trend from early to late stages • problem: in the era of effective HIV therapy a pre-post AIDS comparison may not represent increasing immune deficiency • A new approach • Which cancers occur at increased rates in people with HIV? • How does this compare to transplant recipients? • If the pattern is similar, then it is likely to be immune deficiency, and not shared lifestyle factors, which increase cancer risk

22. HIV-cancer studies Grulich et al, Lancet, 2007

23. Transplant studies Grulich et al, Lancet, 2007

24. Infection-related cancers Grulich et al, Lancet, 2007

25. Infection-related cancers 2: HPV

26. Common epithelial cancers Grulich et al, Lancet, 2007

27. Other cancers increased in one or both Grulich et al, Lancet, 2007

28. Conclusion • A new approach to determine the range of immune deficiency-related cancer • A much larger range of cancers than previously appreciated is associated with transplant and HIV-associated immune deficiency • Most, but not of all of these, are infection-related, and HPV plays a prominent role • The lack of association with immune deficiency in the US AIDS-cancer match may mean that these cancers occur at relatively preserved CD4 counts • The association with degree of immune deficiency may well not be linear, and appears to be different for different cancers • Considerations of increased cancer risk in mild immune deficiency may influence the question of “when to start” HIV therapy.

29. What causes Kaposi’s sarcoma?

30. Kaposi’s sarcoma • A malignancy arising from lymphatic endothelial cells • Gives rise to darkly pigmented lesions of the skin and mucous membranes • Lesions can occur anywhere on skin, and are frequently disfiguring • Involvement of internal organs (respiratory and GI tract) can lead to bleeding and death

32. KS in AIDS • KS was the harbinger of the AIDS epidemic • Relative risk of 50,000 or more • Percent of AIDS defining illnesses • Developed countries • male homosexuals 30-40% • all others < 5% • African heterosexuals 20% + • Risk of KS is raised in homosexual men who report • More sexual activity • A history of sexually transmissible infections • Consistent with a sexually transmissible agent

33. The cause of KS: human herpesvirus 8 Chang et al, Science, 1994 • Discovered in KS tissue in 1994 • Discovered by a molecular biologist-epidemiologist team • A gamma herpesvirus, • found in close to 100% of KS tissue, • rarely described in control tissue • infection precedes development of KS • HHV-8/KSHV is now recognised as the cause of KS • Close relatives found in African green monkeys, other primates • Closest human relative is Epstein Barr Virus • Probably an ancient cross species transmission

34. Risk factors for HHV8 in people with HIV • Homosexual men with serological evidence of HHV-8 infection: • Report more STDs • Report twice as many casual partners • Significantly more likely to report sexual risk behaviours with casual partners • More likely to be HSV2 IgG positive • ie a sexually transmissible infection • HHV-8 serology predicts future development of KS Grulich et al, J AIDS & HR, 1999

35. Pathogenesis • HHV-8 is the necessary cause of KS. • It contains a several recognisable host genes (“molecular piracy”). • The proteins encoded by these genes include some that are homologous to human oncoproteins. • a cyclin that inhibits retinoblastoma protein • bcl 2 like protein that prevents apoptosis. • G protein coupled receptor • an inhibitor of apoptosis mediated by the FLICE pathway • an inhibitor of the interferon signalling pathway • IL-6 (induces B cell proliferation) • three functional chemokines (?Angiogenic) • Products encoded by viral genes directly de-rail cell cycle control • Stopping HHV8 replication should stop carcinogenesis

36. The extra-ordinarily distinctive epidemiology of immune deficiency and of infection with HHV-8 among people with KS led us to the cause Incidence has plummeted in developed countries KS is essentially an opportunistic infection associated with loss of cell-mediated immunity against HHV-8 HHV-8 is under very close control by the immune system: maintenance of immunity prevents KS development When KS presents clinically in a person with HIV, first line therapy is usually anti-retroviral therapy (ARV) Restoration of anti-HHV-8 immunity mostly results in tumour regression This challenges our concept of what is a malignancy KS remains an enormous issue in those sub-Saharan African countries where ARV therapy access is poor and HHV-8 seroprevalence is high Now the most common cancer in sub-Saharan Africa KS: a story (almost) solved

37. KS in SE Sydney, 1972-99 Discovery of HHV-8 KS and sexual transmission KS mainly in homosexual men HIV epidemic Combination therapy 1. Age standardised to Australian population 1991 Source: NSW Cancer Council

38. What causes non-Hodgkin lymphoma?

39. Non Hodgkin Lymphoma • A cancer arising from lymphocytes and presenting as a mass • If presenting in the blood = leukaemia • Common cause of cancer death with incidence rapidly increasing (?recent plateau) • 6th most common cause of cancer death in Western countries • It mainly involves B, not T, lymphocytes (also in HIV) • ie not the target cells for HIV infection • Risk factors largely unknown; immune deficiency important • Rate increased 10 fold in immune suppressed transplant recipients

40. NHL in AIDS • 3-5% of AIDS-defining illnesses • probably more than 10% of AIDS deaths in Western settings • 50-100x more common than general population • Unusual subtypes, aggressive (“high grade”) and often rapidly fatal • Burkitt’s: mild immune deficiency (median CD4 300+) • Large cell-immunoblastic: severe i-deficiency (CD4 50) • Primary CNS: profound immune deficiency (CD4 10) • EBV present in 20% of Burkitt’s lymphoma, 50%+ of LCI NHL and 100% of CNS NHL • Little variation in risk with route of HIV infection • Therefore unlikely to be due to a STI or a BBV

41. Risk factors: NSW case-control study • Design • Cases: 219 people with AIDS NHL in Sydney, 1984-94 • Controls: 219 people with HIV infection without NHL • Matched: degree of immune deficiency (CD4 count) • Data: medical record review • Serial CD4 counts • Long term markers of B cell stimulation (serum Ig, globulin) • Therapies active against EBV Grulich et al, AIDS, 2000

42. Duration of immune deficiency CD 4 count one year prior to match date CD4 count Odds Ratio 95 %CI <20 1.0 20-99 1.04 0.51-2.12 100-199 0.51 0.24-1.05 200-499 0.50 0.25-0.99 500 0.48 0.19-1.16 p trend 0.003 Grulich et al, AIDS, 2000

43. Long term B cell stimulation n cases 216 108 67 47 28 20 n controls 201 110 63 42 23 16 Grulich et al, AIDS, 2000-

44. Indices of the role of EBV • Anti-herpes drugs in the previous year • Acyclovir OR 1.06 (95% CI 0.65-1.71) • no dose effect • no subtype effect • Ganciclovir OR 0.51 (95 % CI 0.20-1.25) • Effective anti-EBV therapy does not prevent AIDS-NHL • Grulich & Law, Clin Inf Dis, 2001

45. AIDS-NHL in the era of effective ARV therapy • Incidence declining • CNS NHL is disappearing in areas where HAART access is universal • an opportunistic infection due to lack of cell mediated immunity against EBV. • restoration of CMI against EBV prevents, and in some cases cures, CNS NHL • Immunoblastic lymphoma declining less • Burkitt’s Lymphoma ?not declining • Treatment of NHL is improving rapidly • No longer universally fatal • Aim to treat HIV (HAART) and NHL (chemotherapy) at the same time if at all possible

46. An unanswered question: what causes NHL? • Why has the incidence of NHL increased rapidly in the developed world over the last 50 years? • What is the role of EBV in the non immune-deficient population? • What is the role of immune deficiency? • Could a mild, sub-clinical form of immune deficiency explain much of the risk of NHL? • Other immune dysfunction • Auto-immune disease (increased risk) • Atopic disease (decreased risk) Grulich et al, JNCI, 2005 Grulich et al, CEBP, 2007

47. InterLYMPH– member studies Next meeting: Sydney July 2008

48. Future directions • Are these cancer-immunity associations reversible? • Would earlier therapy of HIV reduce cancer risk? • Does cancer risk return to normal on the cessation of immune suppression? • Is cancer risk lower among recipients of m-TOR inhibitors? • The role of HPV • Does the wider than expected role of HPV in these settings reflect an important role for HPV in upper aero-digestive cancers in the general population? • Should we be vaccinating men? • What explains the increased rate of specific cancers? • Lung cancer • Lip cancer • Melanoma • Thyroid cancer (in ESRD and kidney transplant patients) • Cancer in other conditions of dysregulated immunity • Primary immune deficiency • Is there a highly prevalent but mild form of immune deficiency or immune dysfunction that could explain why NHL has increased so much?

49. NCHECR, Sydney Professor John Kaldor Dr Claire Vajdic Dr Matthew Law Yueming Li Marina van Leeuwen Michael Falster NSW Cancer Council Dr Xinan Wan Professor Bruce Armstrong Dr Anne Kricker Dr Margaret McCredie Anne-Maree Hughes Marylon Coates ANZDATA Prof Jeremy Chapman Dr Stephen Macdonald Dr Angela Webster St Vincent’s Hospital Dr Sam Milliken Dr Jenny Turner Columbia University, USA Professor Patrick Moore Dr Yuan Chang Viral Epidemiology Laboratory, NCI Dr Denise Whitby Interlymph immunology sub-group Dr Wendy Cozen, UCLA Acknowledgements