Background

Uncontrolled cell growth is a property of all tumors or growths, but such tumors can be benign or malignant. Benign tumors have unregulated cell growth that is localized to one place in the body and is not typically life-threatening. Malignant, or cancerous, tumors are aggressive, invasive and intrude upon and destroy both adjacent and distal (distant) tissues. If left unchecked they can be fatal.

 

Some forms of cancer are inherited and may be transmitted through maternal eggs or paternal sperm while other forms of cancer are acquired from environmental conditions and exposure to carcinogens. Cancer is a genetic disease wherein abnormal changes in the cells’ DNA (genetic mutations) lead to the cells’ dysfunctional growth. The genetic mutations result in errors in both DNA replication and repair. In normal cells, when DNA is damaged the cell either repairs the damage or induces its own cell death (apoptosis). In cancer cells, the damaged DNA is not repaired. Instead, the cell replicates and perpetuates the same damaged DNA. The most common genetic mutations involve the activation of pro-cancer genes or the inactivation of tumor suppressor genes. From either activation or inactivation of these genes, the cells in question proliferate uncontrollably and invade nearby tissues and spread to other parts of the body where they damage or destroy normal cells.

 

Although mutation and damage to DNA does occur on a somewhat periodic basis, the body’s immune system is usually able to detect and eliminate abnormally growing cells. However, if the cancerous tumors are able to evade the immune system’s detection or overwhelm its ability to respond adequately, the cancer cells prevail and proceed with their uncontrolled and unregulated growth. As the cancer cell growth continues and spreads they cause different signs and symptoms that generally depend on the type of cancer, its size, location and its effect on nearby tissues or organs. Cancer can also occur in organs deep within the body and initially not cause any signs or symptoms. With continued proliferation and spread of the cancerous cells, cell clusters or solid tumors are formed. If left untreated, the spreading of cancer cells from a local to a regional area and then throughout the body can cause serious illness. The invasion of other normal tissues can result in various signs or symptoms such as fatigue, non-healing sores and changes in mole characteristics, pain, weight loss, disfigurement, and can impact the function of vital organs. While each cancer type can spread to various areas of the body, malignant cells can typically be found to invade the liver, lungs or brain. Impairment or dysfunction of these critical organs will usually result in the patient’s death.

 

Provided a cancerous tumor can be detected before it has spread and removed at an early stage the prognosis for specific cancer types can be quite favorable. During the later stages of metastatic cancer, in which systemic treatments become the necessity, the removal of tumors via surgery may still be necessary in order to manage pain and preserve organ function. To date there have been three main therapeutic approaches to the removal and management of tumor growth and spreading (metastatic) cancers: surgery, radiation and chemotherapy.

Surgery is the current primary treatment for localized and operable tumors or lesions. In this regard surgery requires cutting away (resecting) the tumor mass and a surrounding margin of healthy tissue to ensure that no cancer cells remain at the tumor site. Surgery can potentially cause both physical disfigurement and/or debilitating effects on organ function. In addition surgery may require a costly and lengthy hospital stay.

 

Radiation therapy is sometimes used in conjunction with surgery to shrink a tumor before surgical removal, or afterwards to destroy any cancer cells that may remain. Unfortunately, the combination of surgery and radiation can be very damaging to nerves, blood vessels, or vital organs within the treatment zone. Radiation is also an expensive therapeutic approach, and requires considerable expertise to administer. Radiation brings with it significant complications, including nausea, diarrhea, dry mouth, taste alterations, loss of appetite, and the real potential for damage to normal tissue, including the formation of new cancerous lesions.

 

Chemotherapy is typically a secondary or palliative treatment to help control systemic tumor growth whereas both surgery and radiation may be considered local treatments. In response to the spread of cancer, physicians infuse chemotherapy agents to circulate throughout the body - system wide - and in high concentrations in order to counter the difficulty that some chemotherapeutic agents have in reaching and penetrating the cell membrane to bring about the intended cancer cell death. Unfortunately, this system-wide application often has serious side effects, killing healthy as well as cancerous cells. The systemic use of chemotherapeutics can produce alopecia (loss of hair); nausea; vomiting; myelosuppression (resulting in reduction in the number of platelets, red cells and white cells found in the circulation, and therefore less resistance to infection); and drug resistance. Unfortunately, chemotherapy is curative for only a few tumor types.

 

Emerging treatments, such as radio frequency (RF) ablation, cryoablation, photodynamic therapy, and percutaneous ethanol injection are all in limited clinical use. Generally, each of the above modalities has drawbacks that potentially limit their broad-based use for the treatment of solid tumors.

 

None of these therapies is able to selectively destroy cancer cells without having some impact on normal both local and distal tissues. Consequently there remains a significant unmet medical need for an approach that can effectively treat cancerous tumors while preserving healthy tissue and minimizing detrimental functional, cosmetic and other side effects.

 

OncoSec’s novel tumor therapies are designed to address the drawbacks of conventional therapies by being tissue sparing; providing potential functional, cosmetic and quality of life benefits; being less invasive and reducing side effects; and potentially reducing both treatment and post-treatment costs.