What Is the Prostate Cancer Vaccine?

Cancer vaccines use tumor cell-associated antigens to awaken the body's immune system against cancer. A U.S. Food and Drug Administration (FDA) advisory board has unanimously approved a proposal to allow Merck's cervical cancer vaccine to be marketed, which means that the human anti-cancer war is about to enter a new era. In addition to HPV, many vaccines have entered the clinic. Although some countries have not received similar FDA approval in view of the huge cost of clinical trials, relying on word of mouth of patients has been on the market for several years, such as the Japanese lotus vaccine. (Hasumi Vaccine).

Chinese name: Cancer vaccine
Foreign name: Merck

Cancer vaccine: Tumor cell associated antigen
To wake people up: Humans target cancer
On behalf of: Cervical cancer vaccine

Cancer Vaccine Overview

The most popular cancer vaccine programs today require the identification and identification of tumor cell-associated antigens. There are hundreds of these antigens. Almost half of ongoing clinical trials involve one or more antigens. Unfortunately, these antigens can only trigger a weak immune system response. If a large number of T cells targeting tumor cell-associated antigens are to be produced, not only the appropriate antigens, but also a variety of stimulus signals are required; without these signals, T cell inactivation and peripheral tolerance will occur. Therefore, the new antigen tests have used various immune stimulating molecules to increase the feedback of the immune system.

HPV Cancer vaccine HPV vaccine

HPV virus (English abbreviation of human papilloma virus) is a papilloma vacuole virus A genus belonging to the Papillomaviridae family. It is a spherical DNA virus that can cause squamous epithelial proliferation of human skin and mucosa. Many, the virus only invades humans, and sexual transmission is the main source of infection. Among female groups aged 18 to 24 who have not had sex, "the probability of infection with the virus is very low." ^[1] Free appointment for HPV vaccination in Hong Kong. ^[1]

The world's first HPV vaccine was launched in the United States in 2006. In 7 years, HPV vaccine was applied in more than 100 countries, which significantly reduced the prevalence of HPV and the incidence of precancerous lesions. At present, HPV vaccine approval in China has entered the phase III clinical trial stage. It is estimated that it will take at least 3-5 years to collect sufficient data. The main method for controlling HPV infection is early detection and treatment. ^[1]

Cancer vaccine cell-mediated

Cell-mediated introduction of antigens is a good method. It uses antigen presenting cells, mainly dendritic cells. The target antigen is first introduced into these cells, and then the dendritic cells containing the antigen are introduced into cancer patients. As more and better antigen-presenting cells are discovered by scientists, and these cells are activated by cytokines (such as GM-CSF), the mechanism for optimizing antibody expression is becoming clearer. With cell mediation, Dendreon's prostate cancer vaccine provence is expected to be the first cancer vaccine to receive FDA (US Food and Drug Administration) approval. In their Phase III clinical data published in October 2008, they stated that the vaccine could reduce the risk of death by 20%.

That is, a new problem has been discovered before-active immunosuppression in the tumor microenvironment. Tumor cells have long been suspected of evading immune tests by not expressing surface antigens. In fact, "escape" is not the full capacity possessed by tumor cells. It can also stimulate regulatory T cells or "hiring" suppressor cells from the bone marrow to induce immune suppression. As a result, things got even more troublesome, and I had to find ways to neutralize this immunosuppression and let the vaccine really work.

Cancer vaccine virus antigen

Cancer vaccine prophylactic vaccine

Some tumors express viral antigens, such as cervical cancer and some melanomas. Immunotherapy can use classic preventative vaccines similar to smallpox and polio (poliomyelitis). In this case, cancer cells overexpress a specific endogenous surface antibody, which triggers passive immunity and controls the tumor to a certain extent. Active immunity takes a different path. Antigens on tumor tissue may be specific or non-specific. The immune system is stimulated by one or more of these antigens and responds. This is active immunity. Active immunity can be achieved in two ways-peptide / protein vaccines and cellular vaccines. Polypeptide / protein vaccines can be divided into two types: the first one uses polypeptide / protein antibodies that are commonly found in certain tumors, and these proteins can be injected directly or introduced into the lesion through some microbial agents to trigger an immune response; It is to isolate the antigen from the patient, and then re-direct the antigen that can trigger the immune system back to the patient.

Cancer vaccine cell vaccine

Cell vaccines are divided into exogenous and endogenous. Exogenous cell vaccines, also known as "finished" vaccines, come from collected tumor samples, and they often contain possible tumor antigens; endogenous cell vaccines, derived from the patient's own tumor tissue, are introduced back into the patient after in vitro modification. Compared with cellular vaccines, peptide / protein vaccines are more similar to existing vaccines designed for infectious diseases. This is a great advantage. Such vaccine systems have been used clinically for decades. Cancer vaccines account for only a small percentage of all commercially developed anticancer drugs, only about 20%. In the more than 20 years since the development of modern cancer vaccines, none has been approved by the FDA, and only five vaccines have been approved by Russia, Canada, Europe, South Korea, and Brazil worldwide. To date, more than 7,000 people have participated in cancer immunotherapy trials, but all of the test agents, even though they performed well in early trials, have stopped in phase III clinical trials.

Cancer vaccine development

Most of the antigens used are related antigens. They are strongly expressed in tumor tissues and are also expressed in normal tissues. The immune system has been "accustomed to" these antigens. With good luck, one or two mutant tumor-specific antigens can be found, but these antigens are often only effective for certain types of tumors with less than 5%, and the effect is difficult to determine, which is very distressing for cancer researchers. Not only that, each type of cancer has its own characteristics, which also causes great trouble for researchers. In theory, all cancers can be immunotherapy, but only a few such as melanoma have received the attention of scientists, and it was the earliest to be found with specific antigens. It was later discovered that the antigen was not specific, and trials using peptide / protein vaccines failed.

Patients with advanced cancer are the preferred test subjects for vaccine development commercial companies, and they can quickly get efficacy data. However, decades of clinical data on cancer vaccines tell us that the effects of immunotherapy are mostly reflected in patients with early cancers or patients with low-grade malignancies, which have been effectively reduced to the microscopic level by surgery or chemotherapy. About 50% of cancer patients can be reduced to minimal residual disease, which is probably the most effective stage for cancer vaccines. But assessing the effect of cancer vaccines on minimal residual tumors is another challenge.

Scientists bring hope to patients again and again, and night after night to drug design and regulators. How to detect and evaluate their efficacy, let them rack their brains. An antigen may be specific or only strongly related; specific antigens may be universally specific, or they may be unique to a patient. To complicate matters, there are more than 30 active cancer immune vaccines that have adopted different production methods and different detection methods. The design of the trial is more complicated, with the early and late stages of each patient, and the design termination time of the trial may vary from time to time. Depending on the diagnosis, there are different sampling times. The results are naturally difficult to evaluate.

Cancer vaccine treatment plan

Cancer vaccine cancer treatment vaccine enters phase III clinical trial

Dr. Oleg Loran's daily job is to treat patients with kidney cancer. However, he did not have much choice in choosing a treatment plan for these cancer patients. If kidney cancer is detected early, the patient's 5-year chance of survival is 60%. However, more than one-third of patients have reached advanced cancer when they are diagnosed, and their 5-year chance of survival has dropped sharply to 11%. So when an innovative product for kidney cancer was approved, Dr. Loran was relieved. Oncophage is a cancer vaccine that prevents cancer from recurring for up to two years. It was developed by American startup Antigenics. But Americans are probably not so lucky. Loran is practicing medicine in Moscow, and Russia is the only country in the world that has approved the listing of Oncophage. The trial data on Oncophage have not convinced the Food and Drug Administration (FDA). To this end, Antigenics must implement another clinical trial that will take 8-10 years and cost $ 500 million, which is far beyond what Antigenics can do. This example also reflects the dilemma faced by anticancer drug development from another aspect.

Cancer vaccine new anti-cancer drug

Since 2005, the FDA has approved 18 new anticancer drugs, many of which are breakthrough products. However, hundreds of anti-cancer drugs being developed by pharmaceutical companies will never enter the market because corporate developers cannot (or are unwilling to) invest the necessary financial resources and energy to recruit patients for trials in order to gain access to regulatory agencies Accepted research data. A study by Tufts University found that only 8% of experimental anticancer drugs were eventually approved by the FDA, compared with 20% of new drugs for other diseases. In fact, the FDA understands the problems. To this end, the FDA announced in 2004 an initiative called The Critical Path Initiative (CPI) to make clinical trials more effective. However, the operation was not supported by much funds from the beginning, and then it was completely silent. Outside the FDA, academics and scientific researchers in the pharmaceutical industry have proposed routine evaluations of drugs through innovative ideas. They complain that the FDA is too conservative and is hesitant to adopt new methods.

Kessler believes that the FDA should comprehensively review its approach to anticancer drug approval. In the late 1980s and 1990s, the FDA established rapid approval procedures for anti-AIDS drugs, which brought protease inhibitors and other breakthrough anti-AIDS drugs to the market one after another, increasing the probability of patients receiving life-saving drugs. Kessler and others hope similar approaches to new cancer drugs, including major reforms in human trials. "For example, mathematical models are used to predict the safety and effectiveness of drugs, and the set goals can be reached within a few months; for example, pharmaceutical companies can break down drug test results based on the target population, and so on. Whether these recommendations can be passed will depend on The ultimate authority is the FDA's Oncology Medicines Office, which is headed by Richard Pazdur, one of the most powerful figures in the medical field. Usually, when clinical trials produce ambiguous results, the Oncology Medicines Office will not release the drug.

Under normal circumstances, a dynamic balance is maintained between cell proliferation and apoptosis. Uncontrolled cell proliferation or blocked apoptosis can lead to tumorigenesis, and GS-Rh2 acts as a messenger of balance. Regulating and inducing apoptosis of tumor cell proliferation cycle is the most basic and effective mechanism of GS-Rh2 antitumor way.