12: Molecular Targeted Therapy

Question 1

Stages in Development of New Cancer Drugs:

1. Preclinical Studies: Laboratory testing on normal and cancer cell lines. _____ testing for efficacy and toxicity.
2. Investigational New Drug (IND) Application: File with FDA for clinical testing in _____.
3. Phase I Trial: designed to determine safe and appropriate _____ for subsequent studies. If successful then Phase II trial starts.
4. Phase II Trial: designed to determine effectiveness and _____ _____ of new drug in one type of cancer. If successful then Phase III trial starts.
5. Phase III Trial: evaluates the effectiveness of new drug and compares it to _____ available standard treatment.
6. New Drug Application (NDA): File _____ (new drug application) or BLA (biologics license application) with FDA/ Submit the Phase _____ trial data that new drug is safe/superior to standard treatment.
7. FDA Approval: FDA _____ new drug if satisfied with Phase III results. Market under a label: drug’s dosage, safety, indications and side effects.
8. Phase IV Trials determine the _____-term safety and effectiveness of new drug.

Answer 1

1. Preclinical Studies: Laboratory testing on normal and cancer cell lines. Animal testing for efficacy and toxicity.
2. Investigational New Drug (IND) Application: File with FDA for clinical testing in humans.
3. Phase I Trial: designed to determine safe and appropriate dose for subsequent studies. If successful then Phase II trial starts.
4. Phase II Trial: designed to determine effectiveness and side effects of new drug in one type of cancer. If successful then Phase III trial starts.
5. Phase III Trial: evaluates the effectiveness of new drug and compares it to best available standard treatment.
6. New Drug Application (NDA): File NDA (new drug application) or BLA (biologics license application) with FDA/ Submit the Phase III trial data that new drug is safe/superior to standard treatment.
7. FDA Approval: FDA approves new drug if satisfied with Phase III results. Market under a label: drug’s dosage, safety, indications and side effects.
8. Phase IV Trials determine the long-term safety and effectiveness of new drug.

Question 2

Chromosome _____ = BCR gene

Chromosome _____ = ABL gene which codes for tyrosine kinase

CML is a clonal bone marrow stem cell disorder in which a proliferation of mature granulocytes of _____ lineage (neutrophils, eosinophils and basophils) and their precursors is found.

After this fusion of BCR-ABL in CML, the gene becomes constitutively active!

Answer 2

Chromosome 22 = BCR gene

Chromosome 9 = ABL gene which codes for tyrosine kinase

CML is a clonal bone marrow stem cell disorder in which a proliferation of mature granulocytes of myeloid lineage (neutrophils, eosinophils and basophils) and their precursors is found.

After this fusion of BCR-ABL in CML, the gene becomes constitutively active!

Mnemonic (A):(B) = 9:22–A from Abl & B from Bcr

Question 3

Treatment for CML

_____ or interferon-a regimen with allogenic stem-cell _____.

< 20% cure rate.

Answer 3

Treatment for CML

Hydroxyurea or interferon-a regimen with allogenic stem-cell transplantation.

< 20% cure rate.

Question 4

_____ (STI-571) binds to the Bcr-Abl protein at its ATP binding site thereby preventing phosphorylation of other proteins and subsequent malignant transformation.

Answer 4

Imatinib (STI-571) binds to the Bcr-Abl protein at its ATP binding site thereby preventing phosphorylation of other proteins and subsequent malignant transformation.

Question 5

Imatinib is used to treat what disease?

Answer 5

Chronic myelogenous leukemia

Imatinib is Standard First-Line Therapy for CML

Question 6

Imatinib (STI571): Mechanism of Relapse and Resistance

Intrinsic Resistance: patients with persistent Bcr-Abl kinase activity due to kinase _____ or drug _____.

Relapse due to _____ in Abl kinase or Bcr-Abl _____ .

Answer 6

Imatinib (STI571): Mechanism of Relapse and Resistance

Intrinsic Resistance: patients with persistent Bcr-Abl kinase activity due to kinase mutation or drug efflux.

Relapse due to mutatations in Abl kinase or Bcr-Abl amplification.

Question 7

_____ Generation Tyrosine Kinase Inhibitors for CML include Nilotinib & Dasatinib.

Answer 7

Second Generation Tyrosine Kinase Inhibitors for CML include Nilotinib & Dasatinib.

Question 8

Nilotinib: Structure _____ to Imatinib

Answer 8

Nilotinib: Structure Similar to Imatinib

Question 9

Nilotinib _____ to that of Imatinib and _____ fit in ABL kinase pocket!

About 20-30-fold more _____ than Imatinib against BCR-ABL in vitro

Active against most BCR-ABL mutants with clinical _____ to Imatinib

Major side effects of _____ obviously: thrombocytopenia, neutropenia and anemia

Answer 9

Nilotinib similar to that of Imatinib and better fit in ABL kinase pocket!

About 20-30-fold more potent than Imatinib against BCR-ABL in vitro

Active against most BCR-ABL mutants with clinical resistance to Imatinib

Major side effects of myelosuppression obviously: thrombocytopenia, neutropenia and anemia

Question 10

Dasatinib: Structure _____ from Imatinib.

It is also an ATP mimetic and binds within the ABL kinase _____.

More than 300-fold more _____ than Imatinib against BCR-ABL in vitro

Active against most BCR-ABL mutants with clinical _____ to Imatinib

Major side effect is Pulmonary _____ _____

Answer 10

Dasatinib: Structure Different from Imatinib.

It is also an ATP mimetic and binds within the ABL kinase pocket.

More than 300-fold more potent than Imatinib against BCR-ABL in vitro

Active against most BCR-ABL mutants with clinical resistance to Imatinib

Major side effect is Pulmonary Arterial Hypertension (PAH)**

Question 11

_____ is also given for Gastrointestinal Stromal Tumors (GIST).

In GISTs there are _____ mutations in genes of KIT and PDGFRA receptor tyrosine kinases.

_____ inhibits KIT and PDGFRA and it is used at 400 mg/day.

Some patients show primary resistance other develop secondary resistance due to secondary KIT and PDGFRA mutations.

Answer 11

Imatinib is also given for Gastrointestinal Stromal Tumors (GIST).

In GISTs there are activating mutations in genes of KIT and PDGFRA receptor tyrosine kinases.

Imatinib inhibits KIT and PDGFRA and it is used at 400 mg/day.

Some patients show primary resistance other develop secondary resistance due to secondary KIT and PDGFRA mutations.

Question 12

Acute Promyelocytic Leukemia (APL), a type of acute myeloid leukemia (AML). A distinct _____ of myeloid differentiation. _____ of immature promyelocytes in marrow and peripheral blood. A reciprocal translocation between chromosomes _____ and _____ in 98% of cases.

Answer 12

Acute Promyelocytic Leukemia (APL), a type of acute myeloid leukemia (AML). A distinct blockage of myeloid differentiation. Accumulation of immature promyelocytes in marrow and peripheral blood. A reciprocal translocation between chromosomes 15 and 17 t(15;17) in 98% of cases.

Question 13

In Acute Promyelocytic Leukemia the t(15;17) translocation fuses the _____ acid receptor a (RARa) gene with _____ leukemia (PML) gene: PML-RARa fusion.

The PML-RARa fusion protein functions as an _____ protein: malignant transformation.

Answer 13

In Acute Promyelocytic Leukemia the t(15;17) translocation fuses the retinoic acid receptor a (RARa) gene with promyelocytic leukemia (PML) gene: PML-RARa fusion.

The PML-RARa fusion protein functions as an oncoprotein: malignant transformation.

Question 14

All trans-Retinoic Acid (ATRA), a metabolite of vitamin A, induced first complete _____ in APL patients. Earliest example of ‘ _____ Targeted Therapy’.

In APL the malignant immature promyelocytes continue to self-renew and proliferate _____ undergoing differentiation.

Answer 14

All trans-Retinoic Acid (ATRA), a metabolite of vitamin A, induced first complete remission in APL patients. Earliest example of ‘Molecular Targeted Therapy’.

In APL the malignant immature promyelocytes continue to self-renew and proliferate without undergoing differentiation.

Question 15

Retinoic acid induces terminal _____ of malignant cells, which subsequently undergo natural _____.

ATRA given concurrently with _____-based regimens.

_____ _____ with ATRA in patients unable to tolerate anthracycline-based approach.

Shifting trends: ATRA concurrently with _____ _____ as initial therapy.

Answer 15

Retinoic acid induces terminal differentiation of malignant cells, which subsequently undergo natural apoptosis.

ATRA given concurrently with anthracycline-based regimens.

Arsenic trioxide with ATRA in patients unable to tolerate anthracycline-based approach.

Shifting trends: ATRA concurrently with Arsenic trioxide as initial therapy.

Question 16

ATRA toxicity = Increased _____ blood count: ‘leukocyte activation syndrome’ or ‘retinoic acid syndrome’

Answer 16

ATRA toxicity = Increased white blood count: ‘leukocyte activation syndrome’ or ‘retinoic acid syndrome’

Question 17

Mechanism of Relapse and/or Resistance to Retinoic Acid:

Induction of cytochrome P450 enzymes that enhance retinoic acid _____ and reduction of retinoic acid in plasma.

Alterations in levels of cytosolic retinoic acid _____ protein II (CRBP II) that may affect retinoic acid transport to its target.

Answer 17

Induction of cytochrome P450 enzymes that enhance retinoic acid catabolism and reduction of retinoic acid in plasma.

Alterations in levels of cytosolic retinoic acid binding protein II (CRBP II) that may affect retinoic acid transport to its target.

Question 18

Epidermal Growth Factor Receptor (EGFR)

Trastuzumab (_____) a humanized monoclonal antibody against Erb-_____.

Erb _____ overexpressed in 25 –30% of advanced breast cancers and predictive of worse prognosis.

ErbB2 is a good target for immunotherapy.

Answer 18

Epidermal Growth Factor Receptor (EGFR)

Trastuzumab (HERCEPTIN) a humanized monoclonal antibody against Erb-B2.

ErbB2 overexpressed in 25 –30% of advanced breast cancers and predictive of worse prognosis.

ErbB2 is a good target for immunotherapy.

Question 19

Mechanism of Action of HERCEPTIN/ Trastuzumab:

Prevents transduction of proliferation and _____ signals.

Growth _____ in ErbB2 overexpressing cells due to antibody-induced _____ regulation of ErbB2 and subsequent _____ of the receptor.

Given in combination with _____ (paclitaxel, docetaxel). Paclitaxel is cytotoxic so induces apoptosis

Answer 19

Mechanism of Action of HERCEPTIN/ Trastuzumab:

Prevents transduction of proliferation and survival signals.

Growth inhibition in ErbB2 overexpressing cells due to antibody-induced downregulation of ErbB2 and subsequent degradation of the receptor.

Given in combination with taxanes (paclitaxel, docetaxel). Paclitaxel is cytotoxic so induces apoptosis

Question 20

Toxicity of HERCEPTIN/ Trastuzumab:

_____ reaction (can still occur even with humanized version).

Ventricular dysfunction and _____ heart failure.
Can enhance the cardiac toxicity of doxorubicin.

Answer 20

Toxicity of HERCEPTIN/ Trastuzumab:

Hypersensitivity reaction (can still occur even with humanized version).

Ventricular dysfunction and congestive heart failure.
Can enhance the cardiac toxicity of doxorubicin.

Question 21

Ado-trastuzumab emtansine (T-DM1): an antibody-drug conjugate

In ErbB2 (HER2)-positive metastatic breast cancer patients with prior _____ history of trastuzumab and/or taxane.

Trastuzumab is conjugated to DM1.

DM1: a derivative of Maytansine, _____ inhibitor.

Tumor Selectivity: Preferential delivery of drug to _____ (HER2) expressing cancers.

A bifunctional reagent: Antibody-drug conjugate undergoes receptor-dependent _____.

Antitumor effects of Trastuzumab remain intact. Drug is released inside cancer cells and causes cytotoxicity.

Major side effects are _____ dysfunction & _____ toxicity.

Answer 21

Ado-trastuzumab emtansine (T-DM1): an antibody-drug conjugate

In ErbB2 (HER2)-positive metastatic breast cancer patients with prior treatment history of trastuzumab and/or taxane.

Trastuzumab is conjugated to DM1.

DM1: a derivative of Maytansine, microtubule inhibitor.

Tumor Selectivity: Preferential delivery of drug to ErbB2 (HER2) expressing cancers.

A bifunctional reagent: Antibody-drug conjugate undergoes receptor-dependent internalization.

Antitumor effects of Trastuzumab remain intact. Drug is released inside cancer cells and causes cytotoxicity.

Major side effects are ventricular dysfunction & hepatotoxicity.

Question 22

Trastuzumab Gastric or Gastro-esophageal Junction Cancer

For treatment of _____-positive advanced gastric or gastro-oesophageal junction cancer.

Trastuzumab plus chemotherapy versus chemotherapy alone.

Outcome: Trastuzumab plus Chemo significantly _____ survival versus chemo alone.

Answer 22

Trastuzumab Gastric or Gastro-esophageal Junction Cancer

For treatment of HER2-positive advanced gastric or gastro-oesophageal junction cancer.

Trastuzumab plus chemotherapy versus chemotherapy alone.

Outcome: Trastuzumab plus Chemo significantly increases survival versus chemo alone.

Question 23

Cetuximab is an anti-Erb _____ (EGFR) monoclonal antibody

Cetuximab binds to Erb _____ with similar affinity as EGF or TGFa. Competes for binding to ligands and inhibits Erb _____ tyrosine kinase activity & growth promoting and survival signals.

Used in combination with radiation therapy

Also, used as a single agent in individuals treated previously with platinum-based regimen.

Major toxicity is pulmonary _____.

Answer 23

Cetuximab is an anti-ErbB1 (EGFR) monoclonal antibody

Cetuximab binds to ErbB1 with similar affinity as EGF or TGFa. Competes for binding to ligands and inhibits ErbB1 tyrosine kinase activity & growth promoting and survival signals.

Used in combination with radiation therapy

Also, used as a single agent in individuals treated previously with platinum-based regimen.

Major toxicity is pulmonary embolism.

Question 24

Rituximab is a monoclonal antibody for _____-Hodgkin’s Lymphoma.

Follicular Lymphoma is a type of Non-Hodgkin’s Lymphoma that involves mature B cells that mostly affects _____ adults.

Classified into Grade 1, 2 and 3

15% of Grade 1 and 2 are early stage lymphomas; directed _____ therapy is effective

Majority of Grade 1 and 2 follicular lymphoma patients have advanced disease; for them two approaches:

1. _____ approach: no initial treatment, single agent (Chlorambucil), combination chemo (CHOP) and/or radiation as needed
2. _____ approach: initial combination chemo (CHOP) plus radiation

Answer 24

Rituximab is a monoclonal antibody for Non-Hodgkin’s Lymphoma.

Follicular Lymphoma is a type of Non-Hodgkin’s Lymphoma that involves mature B cells that mostly affects older adults.

Classified into Grade 1, 2 and 3

15% of Grade 1 and 2 are early stage lymphomas; directed radiation therapy is effective

Majority of Grade 1 and 2 follicular lymphoma patients have advanced disease; for them two approaches:

1. Conservative approach: no initial treatment, single agent (Chlorambucil), combination chemo (CHOP) and/or radiation as needed
2. Aggressive approach: initial combination chemo (CHOP) plus radiation

Question 25

Treatment with Rituximab

Rituximab is a _____ monoclonal antibody with variable region of mice IgG but constant region and Fc portion from human

Effective in many relapsed or refractory follicular lymphomas

Standard dose and schedule: 375 mg/m2 weekly _____ infusion for 4 weeks

Rituximab eliminates CD _____-positive follicular lymphoma cells by Direct activation of apoptosis, Complement activation, Cell-mediated cytotoxicity.

Answer 25

Treatment with Rituximab

Rituximab is a chimeric monoclonal antibody with variable region of mice IgG but constant region and Fc portion from human

Effective in many relapsed or refractory follicular lymphomas

Standard dose and schedule: 375 mg/m2 weekly I.V. infusion for 4 weeks

Rituximab eliminates CD20-positive follicular lymphoma cells by Direct activation of apoptosis, Complement activation, Cell-mediated cytotoxicity.

Question 26

Melanoma:

A highly aggressive malignancy that arises in _____ (cells of skin color).

The cutaneous type is the most common; affects _____, association with exposure to UV.

The acral type affects skin of _____, soles and the area underneath fingernails or toenails.

The uveal type affects melanocytes in other organs for example, in _____ of the eye.

Answer 26

Melanoma:

A highly aggressive malignancy that arises in melanocytes (cells of skin color).

The cutaneous type is the most common; affects skin, association with exposure to UV.

The acral type affects skin of palms, soles and the area underneath fingernails or toenails.

The uveal type affects melanocytes in other organs for example, in iris of the eye.

Question 27

Melanoma:

BRAF gene encodes a _____ threonine kinase.

Mutations in BRAF gene in ~45%-50% of _____ melanomas.

BRAFV600E mutation in the kinase activation domain is the most common. Results in constitutive _____ of BRAF kinase.

Answer 27

Melanoma:

BRAF gene encodes a serine threonine kinase.

Mutations in BRAF gene in ~45%-50% of cutaneous melanomas.

BRAFV600E mutation in the kinase activation domain is the most common. Results in constitutive activation of BRAF kinase.

Question 28

Vemurafenib for treatment of melanomas used for melanomas harboring _____ mutations.

Vemurafenib inhibits BRAF _____.

Side effects:

Cutaneous squamous cell carcinoma (SCC)

QT prolongation and thus, enhanced risk of ventricular arrhythmias.

Should not be given to melanomas harboring _____ type BRAF or to patients with long QT syndrome.

Answer 28

Vemurafenib for treatment of melanomas used for melanomas harboring BRAF mutations.

Vemurafenib inhibits BRAF kinase.

Side effects:

Cutaneous squamous cell carcinoma (SCC)

QT prolongation and thus, enhanced risk of ventricular arrhythmias.

Should not be given to melanomas harboring wild type BRAF or to patients with long QT syndrome.

Question 29

Dabrafenib is a next generation agent used for unresectable stage III and IV or metastatic melanomas that harbor BRAFV600E _____.

Side effects include Serious Febrile Drug Reactions: fever or fever associated with hypotension, rigors or chills, dehydration, or kidney failure.

Should not be given to melanoma harboring _____ type BRAF.

Answer 29

Dabrafenib is a next generation agent used for unresectable stage III and IV or metastatic melanomas that harbor BRAFV600E mutation.
Side effects include Serious Febrile Drug Reactions: fever or fever associated with hypotension, rigors or chills, dehydration, or kidney failure.

Should not be given to melanoma harboring wild type BRAF.

Question 30

Trametinib mechanism of action somewhat different from that of vemurafenib or dabrafenib. Trametinib works _____ stream from the BRAF inhibitors in metastatic melanoma.

Serious _____ Toxicity: rash, dermatitis, acneiform rash, palmar-plantar erythrodysesthesia syndrome, and erythema.

Should _____ be given to melanoma harboring wild type BRAF or to patients previously treated with BRAF inhibitors.

Answer 30

Trametinib mechanism of action somewhat different from that of vemurafenib or dabrafenib. Trametinib works downstream from the BRAF inhibitors in metastatic melanoma.

Serious Skin Toxicity: rash, dermatitis, acneiform rash, palmar-plantar erythrodysesthesia syndrome, and erythema.

Should not be given to melanoma harboring wild type BRAF or to patients previously treated with BRAF inhibitors.