Dr. Peter John M.Phil, PhD Atta-ur-Rahman School of Applied Biosciences (ASAB) National University of Sciences & Technology (NUST)

Gene Therapy & other molecular based therapeutic approaches

Gene Therapy Cancer Gene Therapy Approaches Problems in Therapeutic Trials Clinical Trials Lungs Cancer

Gene Therapy for Cancer Lungs Cancer Breast Cancer Colorectal cancer Malignant Lymphoma, myeloma Leukemias Ovarian

General Treatments Strategies Surgical Radiotherapy Chemotherapy

GT for Cancer Problems Tumour may retained within the treatment area. Inability to differentiate b/w normal & affected cells. To target the therapeutic gene to every tumour cell.

Cancer GT Strategies Gene Augmentation Therapy (GAT) Antisense Oligonucleotides Targeted Killing of specific Cells Immunotherapy Targeted Mutation Correction Targeted Inhibition of gene expression

Augmentation (GAT) It attempts to replace the defective gene with wild type For disease cause by loss of function gene extra copy of gene may increase the amount of normal gene product. Gain of function mutations are not treatable by this approach.

Augmentation (GAT) Adeno & Retrovirus delivery systems have been used for this. Phse-1 clinical trials using augmentation accounts for 7% of the total cancer trials.

Antisense Oligonucleotides Such clinical trials have been used against cellular transcription & translation. Such Oligonucleotides have been used for mutant p53 Problem: Inability to target every tumour cell with the delivery systems

Targeted Killing of Specific Cells In this approach genes are directed to the targeted cells and then expressed so as to cause cell killing. Direct Cell Killing Indirect Cell Killing

Direct Cell killing The inserted genes are expressed to produce a lethal toxins (suicide genes) The gene encoding a prodrug is inserted confirming susceptibility to killing by a subsequently administrated

Indirect Cell Killing We can use immunostimulatory genes to provoke or enhance an immune response against the targeted cells

Suicide GT & Immunotherapy Delivery of toxic genes into to targeted cell. Tumor cell have weak immune response. We can manipulate tumor cells to express cytokines such as IL-2, gamma interferon and TNF to stimulate tumor activity.

Targeted Mutation Correction If inherited gene produce dominant negative mutation. The mutation must be corrected. This approach has yet to be applied but at different levels this can be done. By homologous recombination/at RNA level.

Targeted inhibition of gene If disease display a novel gene product/inappropriate expression of gene. A variety of different systems can be used to block the expression of gene at RNA/DNA or protein level. Allele specific inhibition may be possible in some cases.

Constitutive Androstane Receptor (CAR) gene

Clinical Trials for Lung Cancer In this clinical trial the scientist used gene therapy in combination with radiation therapy to treat lung cancer in 19 different patients

Gene and Radiation Therapy. Intratumoral needle injections of Ad-p53 on days 1, 18 and 32 of the treatment. tumors ≥ 4 cm where injected with 10 ml tumors ‹ 4 cm were injected with 3 ml Radiation therapy

Results 18/19 patients made it through the entire therapy complete response in 2 patients (11%) partial response in 4 patients (21%) stable disease in 1 patient (5%) progressive disease in 11 patients (57%) 57% of the patients showed that the cancer progressed to worse stages Why?

Novel Strategies? Identify more efficient ways to deliver the genes to the patients’ genetic material Develop vectors that can specifically focus on the targeted cells Ensure that vectors will successfully insert the desired genes into each of these target cells

Novel Strategies? Deliver genes to a precise location in the patient’s DNA Ensure that transplanted genes are precisely controlled by the body’s normal physiologic signals

The End