Intro to immunotherapy

Question 1

What % of pts does surgery kill?

Answer 1

~50%

Question 2

What percentage does radiotherapy cure?

Answer 2

20-30%

Question 3

Describe chemotherapy

Answer 3

Systemic cytotoxics e.g. cisplatin (interferes with DNA replication)
Biologics – monoclonal or SMIs

A lot of pts dont respond.

£15,000/course/person

Adverse effects

Question 4

Describe success of standard treatment

Answer 4

• The 5-year survival rate of metastatic testicular cancer is almost 100% due to its sensitivity to platinum chemotherapy
• There have been large improvements in the treatment of prostate and breast cancer due to hormonal targeting of testosterone and oestrogen.
• However, for many cancers, including those of the pancreas, lungs, and oesophagus, not much has changed in the past 40 years, and survival is still very poor.

Question 5

Dr William Coley 1891

Answer 5

• used Coley’s toxin (inactivated Streptococcus pyogenes and Serratia marcescens) for intratumoral injection to stimulate the patient’s immune system, following which, occasional continuous tumour regression was observed

Question 6

What was cancer immunotherapy awarded?

Answer 6

Science’s Breakthrough of the year in 2013

Question 7

Describe first cancer to be targetted by ICIs. What what the mainstay therapy before 2011?

Answer 7

Melanoma

• Stage 0/1 – confined to epidermal region - 100% survival if caught at this point
• Stage 4 – spread to other organs (brain, lungs, liver).
• Surgery is not curative. 5-year survival = 20-30% (before immunotherapy) Therefore, need pharmacological treatment

Pre-2011 standard of care – what were we giving melanoma pts before 2011?:

• Mainstay was dacarbazine which gained FDA approval in 1975
• Dacarbazine (DTIC) - nucleotide analogue - methylates guanine at O-6 and N-7 positions - methylated DNA strands stick together and cannot be repaired - cell cannot divide
  
  • Numerous side effects – immune suppression, sterility, N + V
  • But survival benefit has never been shown in metastatic melanoma patients
• For certain patients we would also give IL-2 immunotherapy, which was approved in 1992 by the FDA…
  
  • T-cell stimulant, cytokine, produced by CD4+ T cells
  • Shown to be capable of inducing proliferation of T lymphocytes in vivo

Question 8

Rosenberg 1985

Answer 8

• administration of recombinant IL-2 intraperitoneally to tumour-bearing mice  regression of small established pulmonary metastases + subcutaneous tumours
  
  • Led to LTS (long-term survival)  effective at high doses but high toxicity

This led to the initiation of clinical trials of recombinant IL-2 in humans

Question 9

Atkins et al (2000)

Answer 9

• Looked at 270 pts entered into clinical trials of IL-2 for metastatic melanoma.
  
  • IL-2 works in 16% of patients (tumour responses were seen) – only worked on a subset of pts
  • However, they showed that these had severe SEs - infections, MI, kidney failure, severe nausea and vomiting etc

Question 10

What came into practice for metastatic melanoma in 2011? (specific name) What are some issues with this?

Answer 10

B-RAF inhibitor, vemurafenib

• Resistance invariably develops
  
  • Patients were recurring with even worse disease than before
  • Now in clinical practice we actually add a MEK inhibitor with BRAF inhibitors which is downstream of BRAF and stops resistance for about 9 months
• But still standard of care if pt has BRAF mutation as improves survival by ~6 months whilst resistance develops

Question 11

Davies, 2002

Answer 11

Did a genome-wide screen in cancer cell lines – DNA seq – found that missense mut in BRAF gene occur in 66% of malignant melanoma. They did used a kinase cascade assay to demonstrate that all four mutants found that elevated basal kinase activity compared to WT BRAF.

Question 12

Patton, 2005

Answer 12

• Found that BRAF cooperates with p53 in the genesis of melanoma.
  
  • Generated zebrafish expressing the most common BRAF mutant form under the control of a melanocyte promoter
  • Expression of mutation but not WT lead to dramatic patches of ectopic melanocytes (nevi)
  • In p53 deficient fish activated BRAF induced formation of melanoma lesions that rapidly developed into invasive melanomas

Question 13

Chapman, 2011 NEJM

Answer 13

• Phase III trial of stage 4 melanoma comparing vemurafenib with dacarbazine in pts with BRAF V600E mutation
  
  • 675 pts - either being given dacarbazine or vemurafenib
  • At 6 months OS was 84% in vemurafenib but 64% in dacarbazine

Vemurafenib = reduction of 74% in the risk of either death or disease progression vs dacarbazine

Question 14

Describe 3 potential situations that occur when immune system meets cancer

Answer 14

1. Elimination
   
   1. Immune system can eradicate early cancer cells, killed by T cells.
   2. CD4/8 T cells recognise tumour association Ags; NK cells activated by tumour ligands, direct killing, chemo/cytokine prod  facilitates killing
2. Equilibrium
   
   1. Immune system controls cancer cells. Occurs in late-stage tumours – they don’t expand but persists. It represents a balanced “dynamic” between the immune system and cancer.
3. Immune exhaustion/inhibition or emergence of tumour cells variants enable tumour to evade immune pressure ….

…Escape

• Cancer cells evade immune system, so tumour cell variants grow. Results in the appearance of clinically detectable tumours  PROGRESSIVE DISEASE
• Immune cells don’t recognise Ags on tumours, instead grow around

Question 15

Give general ev for role of immune system in the control of cancer

Answer 15

• Animals:
  
  • Mice with deficiency in innate/ adaptive systems have higher incidence of spontaneous/ carcinogen induced cancers
  • In mice with a normal immune system cancer cells with immunogenic mutations rapidly depleted (aka immunoediting)
  • Cancers that develop in immunodeficient mice retain immunogenic mutations and are rapidly rejected by normal mice
• Humans:
  
  • Patients with AIDS/ on immunosuppressants have increased incidence of cancer
  • Cancers dormant for long periods can relapse after immunosuppression
  • Donor origin tumours develop in immunosuppressed recipients of organs from asymptomatic donor

Question 16

Zhang et al 2003

Answer 16

The group did immunohistochemical analysis of 186 frozen specimens from advanced stage ovarian cancer and assessed distribution of tumour-infiltrating T cells

• There were significant differences in the distributions of progression-free survival and OS according to the presence or absence of TILs
• The five year OS rat was 38% among pts whose tumours contained T cells and 4.5% among patients whose tumours contained no T cells
• Although this was just correlative data  presence of T cells in tumour correlates with improved survival

Question 17

Galon et al 2006

Answer 17

characterised tumour-infiltrating immune cells in large cohorts of human CRCs by gene expression profiling + in situ immunohistochemical staining (about 500 pts total)

• Used RT-QPCR to evaluate genes related to adaptive immunity and inflammation – they found an inverse relationship between the expression of these genes and tumour recurrent – cav – they looked at a specific set of genes – could they have missed any?
• They used the immunostaining to show that tumours from patients without recurrence had higher immune cell density
• They even found that collectively the immunological data (the type, density and location of immune cells in CRC) had a prognostic value that was a better predictor of patient survival than the histopathological methods currently used to stage CRC
• This suggested that the time to recurrence and the OS time are governed in large part by the state of the local adaptive immune response
• This shows that maybe we could use in-situ analysis of tumour-infiltrating cells as a biomarker/prognosis tool?
  
  • This was only in CRC – might not apply to other cancers
  • This finding has been replicated in many other studies
  • However, there is currently a lack of consensus on methods for the identification, enumeration and scoring of TIL subsets – need to do better

Question 18

What is Immunoscore?

Answer 18

• It is a novel scoring algorithm
• This is a scale and is based on digitally quantified densities of IHC-labelled CD3+ and CD8+ T cells, both in the tumour centre (TC) and in the invasive margin (IM)

Question 19

Pages et al (2018)

Answer 19

• Recent multi-centre study in CRC tissue samples for >2,500 pts. These were analysed by Immunoscore. It had high reproducibility and reliability. Pts with high Immunoscore had sig reduced risk of recurrence at 5 years compared to those with a low Immunoscore
• It has now received regulatory approval for clinic use in colon cancer

Question 20

Afshar-Sterle, 2014

Answer 20

noted that B cell tumours occur in transgenic mice overexpressing BCL6, but only after a really long latency (none had developed it by 200 days). When they genetically ablated the T cell receptor complex in these mice, they developed lymphoma in 8-12 weeks after birth. Therefore, T cells prevent the development of overt lymphomas in mice harbouring a B cell specific Bcl6 transgene  this is even more direct, less correlative evidence

Question 21

• used Coley’s toxin (inactivated Streptococcus pyogenes and Serratia marcescens) for intratumoral injection to stimulate the patient’s immune system, following which, occasional continuous tumour regression was observed

Answer 21

Dr William Coley 1891

Question 22

• administration of recombinant IL-2 intraperitoneally to tumour-bearing mice  regression of small established pulmonary metastases + subcutaneous tumours
  
  • Led to LTS (long-term survival)  effective at high doses but high toxicity

This led to the initiation of clinical trials of recombinant IL-2 in humans

Answer 22

Rosenberg 1985

Question 23

• Looked at 270 pts entered into clinical trials of IL-2 for metastatic melanoma.
  
  • IL-2 works in 16% of patients (tumour responses were seen) – only worked on a subset of pts
  • However, they showed that these had severe SEs - infections, MI, kidney failure, severe nausea and vomiting etc

Answer 23

Atkins et al (2000)

Question 24

Did a genome-wide screen in cancer cell lines – DNA seq – found that missense mut in BRAF gene occur in 66% of malignant melanoma. They did used a kinase cascade assay to demonstrate that all four mutants found that elevated basal kinase activity compared to WT BRAF.

Answer 24

Davies, 2002

Question 25

• Found that BRAF cooperates with p53 in the genesis of melanoma.
  
  • Generated zebrafish expressing the most common BRAF mutant form under the control of a melanocyte promoter
  • Expression of mutation but not WT lead to dramatic patches of ectopic melanocytes (nevi)
  • In p53 deficient fish activated BRAF induced formation of melanoma lesions that rapidly developed into invasive melanomas

Answer 25

Patton, 2005

Question 26

• Phase III trial of stage 4 melanoma comparing vemurafenib with dacarbazine in pts with BRAF V600E mutation
  
  • 675 pts - either being given dacarbazine or vemurafenib
  • At 6 months OS was 84% in vemurafenib but 64% in dacarbazine

Vemurafenib = reduction of 74% in the risk of either death or disease progression vs dacarbazine

Answer 26

Chapman, 2011 NEJM

Question 27

The group did immunohistochemical analysis of 186 frozen specimens from advanced stage ovarian cancer and assessed distribution of tumour-infiltrating T cells

• 102 of the 186 tumours had TILs
• There were significant differences in the distributions of progression-free survival and OS according to the presence or absence of TILs
• The five year OS rat was 38% among pts whose tumours contained T cells and 4.5% among patients whose tumours contained no T cells
• Although this was just correlative data  presence of T cells in tumour correlates with improved survival

Answer 27

Zhang et al 2003

Question 28

characterised tumour-infiltrating immune cells in large cohorts of human CRCs by gene expression profiling + in situ immunohistochemical staining (about 500 pts total)

• Used RT-QPCR to evaluate genes related to adaptive immunity and inflammation – they found an inverse relationship between the expression of these genes and tumour recurrent – cav – they looked at a specific set of genes – could they have missed any?
• They used the immunostaining to show that tumours from patients without recurrence had higher immune cell density
• They even found that collectively the immunological data (the type, density and location of immune cells in CRC) had a prognostic value that was a better predictor of patient survival than the histopathological methods currently used to stage CRC
• This suggested that the time to recurrence and the OS time are governed in large part by the state of the local adaptive immune response
• This shows that maybe we could use in-situ analysis of tumour-infiltrating cells as a biomarker/prognosis tool?
  
  • This was only in CRC – might not apply to other cancers
  • This finding has been replicated in many other studies
  • However, there is currently a lack of consensus on methods for the identification, enumeration and scoring of TIL subsets – need to do better

Answer 28

Galon et al 2006

Question 29

• Recent multi-centre study in CRC tissue samples for >2,500 pts. These were analysed by Immunoscore. It had high reproducibility and reliability. Pts with high Immunoscore had sig reduced risk of recurrence at 5 years compared to those with a low Immunoscore
• It has now received regulatory approval for clinic use in colon cancer

Answer 29

Pages et al (2018)

Question 30

noted that B cell tumours occur in transgenic mice overexpressing BCL6, but only after a really long latency (none had developed it by 200 days). When they genetically ablated the T cell receptor complex in these mice, they developed lymphoma in 8-12 weeks after birth. Therefore, T cells prevent the development of overt lymphomas in mice harbouring a B cell specific Bcl6 transgene  this is even more direct, less correlative evidence

Answer 30

Afshar-Sterle, 2014