MOLECULAR TARGETS AND THEIR SIGNIFICANCE IN THE MANAGEMENT OF NSCLC

MOLECULAR MARKERS AND THEIR ROLE IN THE MANAGEMENT OF NON SMALL CELL LUNG CANCERBY Dr DEEPAK KUMAR DASMOD- PROF. S. GHOSHALDEPT. OF RADIATION ONCOLOGYPGIMER, CHANDIGARH

MOLECULAR BASIS OF CANCER

CLINICAL USEFULLNESS OF MOLECULAR MARKERSDiagnosis of tumour susceptibilityDiagnosis of tumour micrometastasis, including early diagnosis and molecular stagingEvaluation of tumour profiling, such as tumour malignancy and drug sensitivityMolecular targeted therapy

DIAGNOSIS OF TUMOUR SUSCEPTIBILITY Single nucleotide polymorphism(SNP) occurs once per 1000 nucleotide in an individual. These polymorphisms occur within enzymes resulting in change of activity. The metabolic activation of carcinogens by CYP1A1, CYP2A6 and CYP2E1, and their detoxification and inactivation by GSTM1 is altered due their genetic polymorphism.

DIAGNOSIS OF TUMOUR MICROMETASTASIS The presence of tumour micrometastasis is helpful in early diagnosis and molecular staging of tumour. Lung cancer is diagnosed as tumour micrometastasis when gene alteration such as p53, Kras and p16 mutation, and telomerase activity are identified from sputum, blood and bronchoalveolar lavage fluid. EVALUATION OF TUMOUR PROFILING There is no novel prognostic factor with a ultility of determining the prognosis of lung cancer patients equal to staging. But it is possible to estimate the individual drug susceptibility ( tumour drug susceptibility)

The destruction of cell by cisplatin requires binding of the drug to DNA and formation of platinum-DNA adducts. These adducts produce cross link between DNA strands and prevents replication. Nucleotide excision repair has central role in DNA repair and is associated with resistance to platinum based chemotherapy. The excion repair cross complementation group 1(ERCC 1) plays an important role in nucleotide excision repair pathway that identifies and removes cisplatin induced DNA adducts.

PREDICTIVE ROLE OF THYMIDYLATE SYNTHASEThymidylate synthase, an important enzyme in DNA biosynthesis is one of the target enzyme for antifolate drugs.High levels of TS has been shown to be higher in squamous cell carcinoma and correlate with resistance to antifolate drugs such as premetrexedPremetrexed along with cisplatin is approved as first line therapy in advanced lung cancer patients with nonsquamous histology.

TARGETED THERAPYDrugs targeted at pathways, processes and physiology which are uniquely disrupted in cancer cells: ReceptorsGenesAngiogenesisTumour PH

In reality these pathways are not so distinct

IDEAL MOLECULE FOR TARGETED THERAPYThe molecule is uniquely expressed in cancer cells; hence the therapeutic agent will specifically target the cancer and not the normal cells.The molecule is important for the maintenance of the malignant phenotype; therefore once the targeted molecule has been effectively disabled, the cancer cell will not be able to develop resistance against therapeutic agent by suppressing its function or expelling the targeted molecule from the cell.The degree to which target molecules do not embody these characteristicscoupled with nonspecificity of the therapeutic agent determines, in part,the limitations of current targets and agents.

CLASSIFICATION OF MOLECULAR TARGETED THERAPYI-Function directed therapy Cell signaling targeted therapy 1-Blocking of ligand receptor binding a- EGFR family -EGFR1 targeted therapy - Her-2-neu targeted therapy b- Vascular endothelial growth factor(VEGF) c- IGF1R 2- Inhibition of RTKs - Erlotinib - Geftinib 3- Inhibition of intracellular signaling proteins and protein kinases a- Bcr-Abl tyrosine kinase- Imatinib, dasatinib b- Raf/MAP kinase pathway- sorafenib c- PI3K, AKT, and mTOR pathway inhibitors- Everolimus

Angiogenesis targeted therapy Protein degradation targeted therapy- Bortezomib Immune modulation targeted therapyII- Phenotype targeted therapy 1-Nonreceptor protein directed MoAbs a- Unconjugated antibodies- rituximab b- Conjugated antibodies 2- Immunotoxins 3- Cancer vaccines

MOLECULAR MARKERS

EGFR DETECTION METHODS

VeriStat is a commercially available serum or plasma based test utilizing matrix assisted laser desorption ionisation(MALDI) mass spectroscopy methods.

VeriStat assigns each spectrum a binary classification of good or poor. Patients classified as good has a better outcome with the EGFR TKI therapy than clasdsified as poor. A predictive marker

EGFR PATHWAY

TARGETING EGFRBy monoclonal antibodies that target extracellular domain of the receptor or by molecules that bind ATP site and inhibit tyrosine kinase activity of the receptorAbout 10% of patients with NSCLC have activating mutation in ATP binding pocket of EGFR which give rise to prolonged activity in response to ligands such as EGF or TGF-betaActivating mutations are primarily seen in patients having minimal or no smoking history, Asian women and more common in adenocarcinoma than squamous cell carcinomaPatients with wild type, overexpressed EGFR are more likely to show a response of growth restraint but not regression

FREQUENCY OF MUTATIONS

IPASS: STUDY DESIGN

RESULTSGEFTINIBPACLITAXEL PLUS CARBOPLATIN12 Month rate of PFS24.9%6.7%Adverse reaction-Rash or acne(66.2%)-Diarrhoea(46.6%)

-Neurotoxic effects(69.9%)-Neutropenia(67.1%)-Alopecia(58.4%)

NEJ002

No significant difference in overall survival is observed between geftinib andPaclitaxel/carboplatin probably due to high rate of crossover use of geftinib in thePacli/carbo group

INTEREST TRIAL Locally advanced or metastatic NSCLC previously treated with platinum based chemotherapyDocetaxel 75 mg/m2 every 3 weelyGeftinib 250 mg/dayMEDIAN SURVIVAL8 month7.6 monthMEDIAN SURVIVAL( in patients with EGFR mutation)7.5 month8.4 month

INCLUSION CRITERIA Age equal to or more than 18 years Stage IIIB or IV NSCLC Confirmed activating mutation of EGFR

Erlotinib(150 mg/day) until disease progression or toxic side effects4 cycles of gemcitabine and carboplatinMedian PFS 13.1 month 4.6 monthGrade 3 or 4 side effects Increased ALT Skin rashNeutropeniaThrombocytopenia

RESISTANCE TO TKIsSECONDARY MUTATION TO EGFRMost common of these mutations is T790MThreonine at position 790, commonly referred as gate keeperresidue owing to its central location within ATP binding pocket is commonly altered in NSCLC.Mutation of this residue to methionine(T790M) prevents incorporation of both geftinib and erotinib due to steric constraints produced due to decreased pocket size

ACTIVATION OF COMPENSATORY ONCOGENES Amplification and/or mutation of oncogenes with redudant function to EGFR have emerged as another key mode of resistance to TKIs.The best characteristic mechanism of this type is amplification of MET.

EPIGENETIC IDENTITY SWITCHING In presence of prolonged exposure to TKIs, cells undergo multistep process of nonrandom epigenetic switching to an alternative cellular identity. By switching to alternate TKs or reversion to cancer stem cell like identity

IRREVERSIBLE TKIs

These form irreversible, covalent attachments to the EGFR kinase domain. Due to covalent binding, they may have more activity against T790M or secondary mutations against which first generation TKIs are ineffective.

AFATINIBMost extensively studied of 2nd generation TKIsActive against both wild type and mutant forms of EGFRActive against T790MDose- 50 mg orally dailyDose limiting side effects include rash and dyspnea secondary to pneumonitis

LUX-Lung 1

AfatinibPlaceboPFS3.3 month1.1 monthPartial response7%0.5%Stable disease51%18%Disease control rate58%19%

RESULTS

LUX-Lung 2

All patientsN=129EGFR mutationDEL 19/L585ROverall response rate61%65%Disease control rate86%88%Median PFS14 month15 monthMedian OS24 month _

RESULTS

LUX-Lung3

Afatinb 40 mg/day v/s 6 cycle of premetrexed plus cisplatin

(FOR ALL PATIENTS)

FOR PATIENTS WITH COMMONMUTATION(del19/L858R)

LUX-Lung 4

Of 62 patients, 51 patients had acquired resistance to Geftinib /or Erlotinib Only 5 had confirmed objective response. Median PFS is 4.4 month Median OS is 19 month

LUX-Lung 5Patients with advanced NSCLC whose disease progressed after 1st line chemotherapy and an EGFR TKIs: either erlotinib or geftinib( after 12 weeks of treatment)

AfatinibProgression after 12 weeks of afatinib monotherapy

Afatinib plus chemotherapyAfatinib

(RESULT)

LUX-Lung6

(cough)

(dyspnea)

LUX-Lung 7

INCLUSION CRITERIAMale and female patient aged 18 to 90 years Stage IIIB/IV adenocarcinoma of lungDocumented EGFR mutation DEL19 and/or L585RAt least one measurable lesion according to RACIST 1.1ECOG performance status 0 or 1

LUX-Lung 8

OTHER 2nd GENERATION TKIs

NERATINIB An oral irreversible inhibitor of both EGFR and HER2 Active against EGFR T790M Maximum tolerated dose is 320 mg dailyDACOMITINIBAn irreversible pan-HER tyrosine kinase inhibitor with activity against EGFR Maximum tolerated dose is 45 mg orally daily

ALK PATHWAY

REARRANGEMENT OF ALKFound in 3-5% of NSCLCAlso found in anaplastic large cell lymphoma, neuroblastoma, IMTFound in younger patientsMore prevalent in patients having no history of smoking or light smokingAdenocarcinoma histology

FUSION PARTNERS

PROFILE 1014

Crizotinib is an oral small molecule tyrosine kinase inhibitor of ALK, MET and ROS1 kinases.

INCLUSION CRITERIAALK positive Advanced NSCLC No previous systemic treatmentCRIZOTINIB(250 mg twice daily)Premetrexed 500 mg/m2 plus cisplatin 75 mg/m2 or carboplatin AUC 5 or 6 every 3 weekly upto 6 cycle PFS10.9 Month7 monthObjective response rate74%45%Most common adverse eventVision disorder diarrhoea nausea edemaNausea fatigueVomitingDecreased appetite

RESULTS

REARRANGEMENT OF ROS-1ROS-1 is activated by chromosomal rearrangement found in variety of human cancer like NSCLC, cholangiocarcinoma, gastric cancer, ovarian cancer, and GBM.Rearrangement leads to fusion of portion of ROS-1 that includes tyrosine kinase domain with 1 of 12 partner proteins.The resulting fusion kinases are constitutively activated and leads to cellular transformation.Found in 1% of NSCLC.Found in patients who have never smoked or history of light smoking.Adenocarcinoma histology

N= 50Advanced NSCLC Positive for ROS-1RESULTSObjective response rate was 72% Median duration of response was 17.6 monthsMedian PFS was 19.2 months

BEVACIZUMABAngiogenesis is one of the hallmark of cancer.Vascular endothelial growth factor(VEGF) is the major regulator of angiogenesis.Increased expression of VEGF is found in most of human tumors including non small cell cancer.Humanised variant of monoclonal antibody against VEGF (bevacizumab) has shown clinical activity against human cancer.

PCBevacizumab plus PCMedian survival10.3 month12.3 monthMedian PFS4.5 month6.2 month

There were 15 treatment related death in chemo plus bevacizumab arm including 5 from pulmonary haemorrhage.

KRAS PATHWAY

SELUMETINIBKRAS mutation occurs in 20-30% of NSCLC patients.Selumetinib blocks the MAPK kinase(MEK) which is part of KRAS pathway.More specifically, it blocks the subtypes MEK 1 and MEK 2.

Jane PA, J Clin Oncol 2012; 30: Abstr 7503

SELECT 1 TRIALSelumetinib 75 mg bd continuous plus docetaxel 75 mg/m2 on day 1 of every 21 day cyclev/sPlacebo plus docetaxel 75 mg/m2 on day 1 of every 21 day cycleThis study will assess the pharmacokinetics, safety, patient related outcomesAnd tolerability profile of selumetinib/docetaxel compared toplacebo/docetaxel INCLUSION CRITERIAMale or female, aged 18 years or olderHistologically confirmed NSCLC stage III-IVKRAS positive tumour sampleFailure of 1st line chemotherapy

BRAF MUTATION

Found in 2% of lung cancer Poor prognostic indicator

HER 2Activated by homo or hetero dimerisation.Amplification of HER2 is found in 2-4% of NSCLC patients.More prevalent in adenocarcinomaNegative prognostic markerNeratinib, a pan HER inhibitor has shown clinical activity in phase I trials

C-MET

MET amplification occurs in 2-5% of NSCLC patients.Potential mechanism of resistance in EGFR inhibition.Ornatuzumab is a monoclonal antibody against HGFR. In a phase II study, ornatuzumab with erlotinib in comparision to erlotinib with placebo as a means of 2nd or 3rd line therapy did not show any improvement in survival.Tivatinib has high affinity for inactive kinase domain of MET.The randomised, double blind MARQUEE study investigated the addition of tivatinib to erlotinib in NSCLC patients. After a planned interim analysis, the trial was stopped due to futility.

RET

RET amplification occurs in 1.2% of pateients with adenocarcinoma histology, younger patients, light or never smokers and poorly differentiated tumours.Alectinib is potent inhibitor of ALK and shown anti tumour activity against RET. Other TKIs such as vandetanib, cabozantinib, ponatinib have shown activity against RET

FGFR1

FGFR1 amplification occurs in 20% squamous cell ca of lung and 5% of adenocarcinoma.More common in male smokersAssociated with poor outcomeClinical trials with FGFR inhibitors are ongoing.

DDR2Discoidin domain receptor 2DDR2 mutation is found in 4% of NSCLC patientsMultikinase TKI dasatinib has shown clinical activity against DDR2.

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TOXICITY

Median onset of cutaneous toxicity is after 1-2 weeks of initiation of treatment With maximum intensity at 2-3 weeks. Rash appears to be dose related and most patients experience transient mild to moderate symptoms. Moderate to severe rash occurs in 10% patients.

CONCLUSIONEGFR TKIs are the most extensively studied of targeted therapies in NSCLC.Cells develop resistance to TKIs leading to development of 2nd generation TKIs.In most studies, TKIs shows improvement in PFS without any benefit in OS.In cost effective analysis, targeted therapies show very minimal gain in live year and quality adjusted live year.Despite these, it gives an impetus to move from ready made therapy to tailor made therapy.

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