What Are Monoclonal Antibodies?

Monoclonal antibodies are highly homogeneous antibodies produced by a single B-cell clone that target only a specific epitope. It is usually prepared by hybridoma technology. Hybridoma antibody technology is based on cell fusion technology, which fuses sensitized B cells with the ability to secrete specific antibodies and myeloma cells with infinite reproduction ability to B-cell hybridization. tumor.

Monoclonal antibodies are produced by artificially prepared hybridoma cells. Hybridoma cells are formed by the fusion of an antigen-activated B cell with a myeloma cell. The advantages of monoclonal antibodies: high purity, high sensitivity, strong specificity, less cross-reactivity, and low cost of preparation. Disadvantages: There are certain requirements for the technology, and the epitope is easily lost through the chemical treatment of the antigen ^[1]

GJF, molecular biologist, 1975

Immunized animal

Immunizing animals is the process of immunizing mice with the antigen of interest to cause mice to sensitize B lymphocytes. Generally, 6-8 week-old female BALB / c mice are selected for immunization according to a pre-established immunization schedule. Antigens enter through blood or lymph circulation

Antigen refers to the ability to stimulate the body to produce a (specific) immune response, and to bind to the immune response product antibody and sensitized lymphocytes in vitro to occur

BALB / c mice are generally used as host animals for monoclonal antibody preparation. Murine monoclonal antibodies have a wide range of applications. Some domestic and foreign companies have developed rabbit monoclonal antibody preparation techniques.

The immunogen is divided into soluble antigen and granular (cell) antigen. It is diluted with sterile saline and mixed with adjuvant. The stable emulsion formed by intraperitoneal injection of antigen and adjuvant is thoroughly mixed to provide a basis for continuous immune response in immunogen Booster

0.2ml of blood was collected on the first day of the cycle (0.1ml of pre-immune serum was obtained)

First immunization (antigen plus

1. material

1. Hybridoma cell chromosome inspection using

The positive wells tested for antibodies can be expanded and cloned to obtain monoclonal antibodies secreted by the progeny of a single cell. Cloning is generally done as soon as possible. Because during this period various

(A) Spleen cells

1. material

(1) Immune

Since the advent of monoclonal antibodies, due to their unique characteristics, they have rapidly been used in many fields of medicine. It is mainly manifested in the following aspects.

1. Laboratory medicine

1. Advantages of monoclonal antibodies

(1) Hybridomas can survive and be passaged "permanently" in vitro, as long as no genetic mutations in the cell line occur, they can continuously produce highly specific and highly uniform antibodies.

(2) A large number of highly specific and uniform antibodies can be obtained with relatively impure antigens.

(3) Since it is possible to obtain an "infinite amount" of uniform antibodies, it is suitable for

The development of monoclonal antibody drugs originated in 1975, and the advent of hybridoma technology made it possible to prepare a large number of uniform mouse monoclonal antibodies. Muromab-CD3 (OKT3), the first murine monoclonal antibody against immune rejection after transplantation in 1986, was approved for marketing by the Food and Drug Administration (FDA), but originated from hybridization of murine lymphocyte Tumor antibodies are recognized by the human immune system and cause a severe human anti-mouse antibody (HAMA), which not only shortens the half-life of the therapeutic monoclonal antibody, weakens the efficacy, and sometimes causes serious adverse reactions. .

The development of monoclonal antibody drugs fell into a trough between 1988 and 1993. With the development of recombinant DNA technology, various antibody humanization technologies have developed rapidly. Monoclonal antibody drugs have undergone the stages of human and mouse chimeric monoclonal antibodies and humanized monoclonal antibodies. Subsequent phage display library technology and transgenic mouse technology enabled the production of fully human monoclonal antibodies, the first fully human antibody in 2002

The development of monoclonal antibodies has gone through four stages, namely:

Murine monoclonal antibodies, chimeric monoclonal antibodies, humanized monoclonal antibodies and fully human monoclonal antibodies.

Fully human-derived monoclonal antibodies: The variable and constant regions of the antibodies are of human origin, eliminating immunogenicity and toxic side effects.

Relevant technologies for the preparation of fully human antibodies include:

Human hybridoma technology, EBV transformed B lymphocyte technology, phage display technology, transgenic mouse antibody preparation technology (transgenic mouse) and single B cell antibody preparation technology, etc.

Humanized and fully human antibody drugs prepared from humanized and fully human antibodies have overcome the shortcomings of animal-derived antibodies and chimeric antibodies because of their high affinity, high specificity, and low toxicity. Has become an inevitable trend in the development of therapeutic antibody drugs.

Sales and growth

In 2010, the total sales of monoclonal antibodies for treatment reached US $ 44 billion. If US $ 10 billion of monoclonal antibody diagnostic and research reagents are added, the total market for monoclonal antibodies will reach US $ 55 billion. The total market for monoclonal antibodies in 2011 has reached US $ 62.8 billion. In the future, global monoclonal antibody drugs will still maintain a high growth rate. By 2015, global monoclonal antibody drug sales are expected to reach about 98 billion US dollars. China's monoclonal antibody drugs have been developed from scratch and are playing an increasingly important role in China's pharmaceutical market. At present, the size of the monoclonal antibody market in China is increasing by more than 50% every year. Monoclonal antibodies are still high-end products in the Chinese market and are mainly imported. Roche is the biggest winner in the monoclonal antibody market in China. Both the rituximab and trastuzumab with the highest market share are from Roche Pharmaceuticals. The share of all Roche products exceeds half of the domestic monoclonal antibody products. In 2010, China's oncology drug market sales reached 16 billion yuan, an increase of 24% year-on-year, ranking seventh globally, far exceeding the United States 4.4% and other mature or emerging markets; in 2011, market sales reached 20.8 billion yuan. 30% year-on-year growth. One of the factors limiting the market penetration of biosimilars is legislation, which prevents the use of biosimilars to replace original products. This means that the use of biosimilars is limited to new patients and short-term indications. However, the opportunities for medical cost control created using biosimilars are huge. In markets that have not yet established a regulatory path for biosimilars, including the United States, the key factors for the success of biosimilars are patent exclusivity, clinical trial requirements, and interchangeability.

R & D policy support

During the "Twelfth Five-Year Plan" period, China's "Major New Drug Creation" project will receive 10 billion yuan from the central government and 30 billion yuan from supporting funds. The special strategic focus includes research and development of innovative drugs, and technological transformation of large drug varieties. The research and development of drugs for 10 major diseases such as malignant tumors, cardiovascular and cerebrovascular diseases, neurodegenerative diseases, diabetes, and tuberculosis is the focus of funding support.

During the "Twelfth Five-Year Plan" period, the development goal of the pharmaceutical industry is an average annual increase in total output value of 20%, to reach 3.1 trillion yuan by 2015.

In 2011, monoclonal antibody drugs continued to lead the global pharmaceutical market, with a large year-on-year growth.

From 2000 to 2010, the compound growth rate of the global monoclonal antibody drug market was as high as 32%.

In 2011, 6 of the top 20 prescription drugs worldwide were monoclonal antibody drugs, of which 5 had sales of more than $ 5 billion. Previously in 2009 and 2008, the figures were $ 40 billion and $ 37 billion, respectively. Currently, almost all large pharmaceutical companies have monoclonal antibody R & D projects.

Among the 20 best-selling medicines in the world in 2011, Pfizer's atorvastatin calcium, which is used to lower cholesterol, ranked first, reaching $ 13.3 billion. In 2011, the global market size of biopharmaceutical products exceeded US $ 155 billion, accounting for 25% of pharmaceutical / biopharmaceutical products. However, some research data show that the proportion of biopharmaceutical products in the global market will increase significantly in the next few years.

It is predicted that by 2014, the top three products in global sales will be biotech drugs (Avastin, Humira and Enbrel), and their total sales will reach $ 25.4 billion.

Monoclonal antibody drugs have become the most important category in biopharmaceuticals. The sales of the seven largest antibody drugs in 2011 reached 38.82 billion US dollars, accounting for nearly 50% of the total biopharmaceutical market; monoclonal antibodies are still being developed The hot spot will also be an important driving force for the development of the biopharmaceutical industry in the future ^[2] .