Targeted Therapies in Hematology & Oncology

Mark B Juckett MDSection of Hematology/BMT

University of Wisconsin

Classical Drug Discovery

Targeted Therapy

Therapeutics directed at specific molecular “lesions” responsible for carcinogenesis

Examples:• tyrosine kinase pathway (bcr-abl, PDGF)• proteosomal pathways• survival signals (MCL1, BCL2)• heat shock proteins• immunological activation/tolerance

Chronic Myeloid Leukemia (CML)and Targeted Therapy

CML

– Cancer of the hematopoietic stem cell

– Well-characterized molecular pathogenesis

Philadelphia (Ph) chromosome

– First abnormality associated with cancer

Bcr-Abl tyrosine kinase

– A single molecular abnormality that causes transformation of a hematopoietic progenitor into a malignant clone

Epidemiology of CML

Median age range at presentation: 45 to 55 years

Incidence increases with age

– 12%–30% of patients are >60 years old

Male-to-female ratio–1.3:1

At presentation

– 50% diagnosed by routine laboratory tests

– 85% diagnosed during chronic phase

CML - Age specific incidence

BMT Candidates

Clinical Course: Phases of CML

Chronic phase

Median 5–6 yearsstabilization

Accelerated phase

Median duration6–9 months

Blast crisis

Median survival3–6 months

Advanced phases

Therapies for Advanced Stages of CML

Usual therapy Hematologicresponse

(complete)

Cytogeneticresponse

Survival

Accelerated phase Various single-agent orcombinationchemotherapy, IFN-

<50% anecdotal <18 months

Blast crisis Acute leukemia typemultiagentchemotherapy

20%–40%(5%–30%)

anecdotal 3–6 months

Essentially, NO effective treatment

Therapeutic Options for CML

Allogeneic stem cell transplantation (SCT)

Interferon - alpha

hydroxyurea (busulfan, 32P)

Imatinib mesylate (formerly STI571)

Allogeneic Stem Cell Transplant in CML

International Bone Marrow Transplant Registry: 1990–1995

HLA = human leukocyte antigen; MUDs = matched unrelated donors.www.bmtinfo.org. Accessed June 11, 2000.

HLA-identical siblingsMUDs

1 2 3 4 5Years From BMT

P=.0001

100

80

60

40

20

0

Pro

ba

bil

ity

(%

) o

fL

eu

ke

mia

-Fre

e S

urv

iva

l

Chronic Phase (N=1756)

Chronic Phase (MUD) (N=391)

Blast Phase (N=72)

Accelerated Phase (N=262)

•Only Curative Treatment

IFN-: Clinical Results in CML

CHR = complete hematologic response.1.Kantarjian HM et al. Ann Intern Med. 1995;122:254-261; 2. Ozer H et al. Blood. 1993;82:2975-2984; 3. Mahon F et al. Blood. 1994;84:3592; 4. Hehlmann Ret al. Blood. 1994; 84:4064-4077; 5. Italian Cooperative Study Group on CML. N Engl J Med. 1994;330:820; 6. Allan NC et al. Lancet. 1995;345:1392-1397; 7. Ohnishi K et al. Blood. 1995;86:906-916; 8. Silver RT et al. Blood. 1996;88 (suppl 1) 638a; 9. Tura S et al. Blood. 1998;92 (suppl 1) 317a; 10. Guilhot F et al. N Engl J Med. 1997;337:223-229; 11. Kantarjian HM et al. J Clin Oncol. 1999;17:284-292.

Response

IFN- (results from 7 clinical trials)1-7

IFN- + Ara-C (results from 4

clinical trials)8-11 CHR (%) Cytogenetic responses (%) Any Major

31–80

18–58 6–38

64–92

41–74 10–50

3-year survival rates (%)

79

86

Complete Cytogeneic response 10 – 15%

Cytogenetic Response and Survival With IFN-

Guilhot F et al. N Engl J Med. 1997;337:223-229.

Major response

Pro

po

rtio

n S

urv

ivin

g

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0.0

0.0 12 24 36 48 60

Minor or no response

P < .001

Months After Treatment

Chemotherapy: Chronic Phase CML

Oral cytotoxic agents– Hydroxyurea - standard treatment for rapid control– Busulfan - rarely used, toxic, decreased survival

Hematologic response in up to 90% of patients

Well tolerated

No cytogenetic effects

Palliative care—no effect on disease progression

Cytogenetic Abnormality of CML:The Philadelphia Chromosome

•Discovered in 1960 by Nowell and Hungerford•First consistent genetic “lesion” in human cancer

The Ph Chromosome: t(9;22) Translocation

22

bcr

abl

Ph ( or 22q-)

bcr-abl

FUSION PROTEINWITH TYROSINEKINASE ACTIVITY

9 9 q+

p210Bcr-Abl Fusion Protein Tyrosine Kinase

Faderl S et al. N Engl J Med. 1999;341:164-172.

Extracellular space

Y177

BAP-1 GRB2

Cytoplasm

SH3 SH2 SH1

CBL SHC CRKL

bcr-abl Gene and Fusion Protein Tyrosine Kinases

Adapted from Melo JV. Blood. 1996;88:2375-2384.

p210Bcr-Abl

p185Bcr-Abl2-11

2-11

Chromosome 9

c-bcr

Chromosome 22

c-abl

Exons

Introns

CML Breakpoints

ALL Breakpoints

1

2-11

Bcr-Abl as a Therapeutic Target for CML

Bcr-Abl translocation is detected in all patients with CML

Bcr-Abl tyrosine kinase is the causative abnormality of CML

Bcr-Abl tyrosine kinase is constitutively activated in CML cells, and activation is necessary for growth

Inhibitors of Bcr-Abl inhibit the growth of CML cells

Imatinib mesylate specifically blocks the function of Bcr-Abl

Steps to Develop Imatinib mesylate

Study and understand the Bcr-Abl tyrosine kinase• homologous to abl, PDGF, c-kit proteins

Design a molecule that blocks the activation site• i.e. the ATP binding site

Refine the molecule to enhance specificity Add a chemical group to allow it to work as a pill Test the compound on CML cells in the lab Determine whether it is safe Test the new drug in patients

Structure of Imatinib Mesylate

Class: Phenylaminopyrimidines, 589.7 mw

C29H31N7O•CH4SO3

• CH3SO3H

Mechanism of Action of Imatinib Mesylate

Goldman JM, Melo JV. N Engl J Med. 344:1084-1086.

Cellular Selectivity of Imatinib Mesylate: IC50 M

Kinases Inhibited Kinases Not Inhibited

v-ABL 0.1–0.3 Flt-3 >10

p210Bcr-Abl 0.25 c-Fms, v-Fms >10

p185Bcr-Abl 0.25 EGF receptor >100

TEL-Abl 0.35 c-erbB2 >100

PDGF-R 0.1 Insulin receptor >100

TEL-PDGF-R 0.15 IGF-I receptor >100

c-Kit 0.1 v-Src >10

JAK-2 >100

PDGF-R = platelet-derived growth factor receptor; EGF = epidermal growth factor; IGF-I = insulin-like growth factor-I.Druker BJ et al. Nat Med. 1996;2:561-566.

Effect of Imatinib Mesylate on Growth ofBcr-Abl–Positive and Bcr-Abl–Negative Cell Lines

Gambacorti-Passerini C et al. Blood Cells Mol Dis. 1997;23:380-394.

*Bcr-Abl–negative cell lines.

†Bcr-Abl–positive cell lines.

Imatinib Mesylate Concentration (M)

U937*KG1*SU DHL1*

KCL22†

K562†

KU812†

Imatinib Mesylate: Rapid Hematologic ResponseW

BC

x 1

03

100

10

10 30 60 90 120 150

Days on Imatinib Mesylate

Imatinib Mesylate: Steady-State Pharmacokinetics

Rapidly and completely absorbed after oral administration

Absolute bioavailability 98%

Terminal half-life (t1/2) 18–22 h; volume of distribution

435 L; and clearance 14 L/h

Linear and dose-proportional increase in AUC with doses

25 mg to 1000 mg

Clinical Trials Phase I Conclusions

Well tolerated with a mild side-effects profile

In all phases of CML, imatinib mesylate achieved– Hematologic responses– Cytogenetic responses

Time to response was rapid

Phase II Studies With Imatinib Mesylate

3 large international trials have been conducted– 0110: Patients with CML in chronic phase

after failure of IFN- therapy – 0109: Patients with CML in accelerated phase– 0102: Patients with CML in myeloid blast crisis

Study design and objectives– Open-label, multicenter, noncontrolled– Imatinib mesylate dose: 400 mg to 600 mg– Assess safety, efficacy, and survival rate

Phase II Study Patients With CML Kantarjian, et al, 2002

Patients with CML Chronic phase after IFN failure

Accrual time: December 1999 to May 2000

Patients with CML in chronic phase:

– Hematologic failure

– Cytogenetic failure

– IFN- intolerant Primary endpoint: cytogenetic response

NEJM 346:645, 2002

Chronic Phase: Patient Demographics (n=532)

Median age [yrs] (range) 57 (18–90)

IFN- failure– Hematologic failure 152 (29%)– Cytogenetic failure 186 (35%)– IFN- intolerance 194 (36%)

Months from diagnosis (range) 32 (3–218)

Months of prior IFN-* (range) 14 (>1–135)

* IFN- at doses >25 MIU/week. NEJM 346:645, 2002

Cytogeneic and Hematologic Responses

All Patients Patients intolerantto interferon

CytogeneticResponse Complete 41% 47% Partial 19% 19%

HematologicResponse

95% 93%

NEJM 346:645, 2002

•Median time on treatment was 17.5 months

Time to Progression to Advanced disease

•Rate of progression-free survival was 89% at 18 months

NEJM 346:645, 2002

Time to Progression According to Cytogenetic Response

NEJM 346:645, 2002

•Major cytogenetic response includes complete and partial responders

Prognostic Factors associated with Major Cytogenetic Response

Response to interferon therapy Time since diagnosis of CML Presence of anemia at diagnosis Presence of Blasts in peripheral blood Presence of Blasts in the bone marrow

NEJM 346:645, 2002

Adverse Events related to Treatment

Event Any Grd 3 or 4

Edema 60 1.1

Nausea 55 1.5

Muscle Cramps 49 0.9

Rash 32 3

Diarrhea 29 0.9

Neutropenia 27 8.1

Weight gain 26 4.3

Vomiting 23 0.6

Myalgia 20 0.2

NEJM 346:645, 2002

Accelerated Disease Study: ResponsesTalpaz, et al, 2002

400mg dose 600 mg dose

Cytogenetic Response

Complete 11% 19% Partial 5% 5%

Complete Hematologic Response

27% 37%

Blood 99: 1928, 2002

Time to Hematologic and Cytogeneic Response

Blood 99: 1928, 2002

Overall Survival

Blood 99: 1928, 2002

P = 0.01

Blast Crisis Study: Responses

Sawyers et al Blood 99:3530

Kantarjian et al Blood 99:3547

Cytogenetic Response

N = 260 N = 75

Complete 7% 7% Partial 9% 4%

Any Hematologic Response ( 4 wks)

31% 46%

•Median time to major cytogenetic response was 3 months•Most patients treated with 600mg

Hematologic Response Duration

•Median duration of response 10 months

Overall survival (229 pts)

•Median survival time 6.9 months

Gleevec vs. Interferon for new CML

International Randomized Study – Phase III 1,106 patients, 177 center, 16 countries Gleevec 400 mg/day

• vs INF 5 MIU/M2/day with Ara-C 20mg/M2/day

10 days per month Median follow-up 14 months

Gleevec vs. Interferon for new CML

Gleevec INF/ARAC

Cytogenetic Response

Complete 69% 12% Partial 15% 30%

Complete Hematologic Response

96% 67%

•Interim analysis presented at ASCO 2002

Considerations When Using Imatinib Mesylate

Imatinib mesylate should be taken with food and a large glass of water

Exposure to imatinib mesylate may increase if liver function is impaired

Effect of renal or liver insufficiency not well studied Use in pregnancy unknown Potential for drug interactions

– P450-CYP3A4 or CYP2D6 inhibitors and substrates

Cytochrome p450 - CYP2D6

Substrates Amitriptyline captopril Beta-blockers Morphine derv. Cyclophosphamide Antiarrhythmics Tamoxifen Nicotine

Inhibitors Amiodarone Celecoxib Chlopromazine Cimetidine Fluoxetine Ritonavir Valproic acid Methadone

Substrates - concentration increases when given with GleevecInhibitors - concentration of Gleevec increases when given with Inhibitor

Cytochrome p450 - CYP3A4

Substrates Acetaminophen Amiodarone Nifedipine Cyclosporin Corticosteroids Warfarin Cannabinoids Estradiol Pantoprazole

Inhibitors Amiodarone Azithromycin Cyclosporine Metronidazole Itraconazole Ranitidine Troglitazone

Substrates - concentration increases when given with GleevecInhibitors - concentration of Gleevec increases when given with Inhibitor

Imatinib Mesylate—Use in CMLPractical Considerations

Side Effect Possible Management

Cytopenia Dose reduction, interruption, or discontinuation

Diarrhea Supportive care

Edema Diuretics, supportive or localized care

Fluid retention Diuretics, supportive measures, dosereduction, interruption, or discontinuation

GI upset Take with a meal and a large glass of water

Muscle cramps Ca2+ supplementation, tonic (quinine) water

Rash Topical or systemic steroids, dose interruptionor discontinuation

Imatinib Mesylate: Dosing

In chronic phase CML– 400 mg once daily

In advanced phase CML– 600 mg once daily

Imatinib mesylate is supplied as 100-mg capsules Dose escalation (400 mg to 600 mg or 600 mg to 800 mg) may

be considered:– Disease progression– Failure to achieve a hematologic response after

at least 3 months– Loss of a previously achieved hematologic response

Conclusions: Imatinib Mesylate in CML

Therapy specifically designed to target the molecular cause of CML

– Potent and selective inhibitor of Bcr-Abl

Improved rates of hematologic and cytogenetic responses in all stages of disease

Encouraging survival and time to progression - so far

• Survival compared to IFN unknown

Favorable side-effects profile (compared to IFN)

Convenient once-daily oral dosing (but $$$)

Imatinib Mesylate use in Solid Tumors

Additional molecular targets– c-Kit– PDGF-R

Relationship to prognosis and malignant transformationis unknown

Tumors associated with these targets– Sarcomas– Lung cancer– Prostate cancer– Gliomas and neuroblastoma– Breast cancer– Seminomas and germ-cell tumors

Evidence for mutations leading to constitutive activation

KIT Expression in Human Malignancies

Tumor type KIT Proteinexpression

c-kit Genemutation

Mastocytosis 100% >90%

GIST 100% >70%

Seminoma 78-100% 9%

Melanoma 90% ?

Thyroid 100% ?

Ovarian 70-90% ?

JCO 20:1692, 2002

Tyrosine Kinase Inhibitors to KIT

Compound KIT IC50 Other Targets

STI571 0.1 Bcr-abl, PDGFR

SU4984 <5 PDGFR, IR, FGFR

SU5416 0.1-1.0 KDR, PDGFR, FGFR

SU5614 0.05-0.1 KDR, PDGFR, FGFR

SU6577 <5 PDGFR, KDR

PTK787 0.73 KDR, FLT1, FMS

Gastrointestinal Stromal Tumors (GIST)

Infrequent tumor (~0.2% of all GI tumors) Occur primarily in stomach (60%–70%) and small intestine Therapeutic options

– Surgery was only effective modality– Few respond to chemotherapy

Outcomes– For unresectable/metastatic disease

• Estimated time to progression <2 months

• Estimated survival <1 year

Distinguishing GIST from sarcomas is difficult Arise from GI mesenchymal stem cells Gain-of-function mutations in c-kit appear to be the most

important alteration leading to the formation of GIST Abnormal KIT signaling in GIST may be the result of genetic

mutations in the DNA of the c-kit gene GIST cells are positive for KIT (CD117) in 100% of cases

Pathology of GIST

Microscopic Appearance of GIST

H+E Stain CD117 (c-kit) Stain

GIST

NormalSmall

Intestine

Normal Functions of c-KIT

KIT is tyrosine kinase found in many normal tissues and is essential for Hematopoiesis (blood cell development) Melanogenesis (development of skin pigmentation) Fertility

Activation of KIT plays a critical role in different cell functions Proliferation (cell multiplication) Differentiation (cell maturation) Apoptosis (programmed cell death) Adhesion (cell attachment)

June 27, 2000 October 4, 2000

3 March 2000 5 April 2000

First GIST Patient After 4-Week Treatment With Imatinib Mesylate

Joensuu et al. N Engl J Med. 2001;344:1052-1056.

EORTC Phase I Study of Imatinib mesylate

Primary objective: Establish a maximum tolerated dose (MTD) for GIST patients

Secondary objective: Determine efficacy

40 patients, 36 with documented GIST Dose administered at 400mg daily and

increased by 200mg increments, up to 1000mg

Proc ASCO 20:1a, abst 2, 2001

MTD = 800mg daily dose with 1000mg leading to DLT’s Objective Response = 69.4%

• PR = 52.7%• SD = 16.7%

Adverse events (AEs) were mild to moderate in severity Most patients experienced relief of symptoms after one

week of treatment

EORTC Phase I Study: Results

Proc ASCO 20:1a, abst 2, 2001

Phase II Study: Objectives

Primary objective: assessment of clinical and biologic activity in GIST patients

Secondary objectives:• Time to onset of response• Duration of response• Time to treatment failure

JCO 20:1a, abst1, 2001

Phase II Study: Patient Characteristics

n (%)

Total 147 (100)Age - median 54 (18–83)ECOG PS

0 62 (42)Recurrent tumor 132 (90)

Liver 115 (78)Peritoneum 56 (38)Retroperitoneum 21 (14)

Previous therapy Surgery 144 (98)Chemotherapy 75 (51)

JCO 20:1a, abst1, 2001

Phase II Study:Best Confirmed Responses

All Doses(N=147)

400mg n=73600mg n=74

Best Response

Complete response (CR) 0Partial response (PR) 40%Stable disease (SD) 41%Progressive disease (PD) 12%Not evaluable 5%

JCO 20:1a, abst1, 2001