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