Question: What is the amount of proteins that targeted therapeutics initially conceived?
About the article "Chemotherapy", section "Cytotoxics and targeted therapies".

Candidate passages:
Targeted therapies are a relatively new class of cancer drugs that can overcome many of the issues seen with the use of cytotoxics.
They are divided into two groups: small molecule and antibodies.
The massive toxicity seen with the use of cytotoxics is due to the lack of cell specificity of the drugs.
They will kill any rapidly dividing cell, tumor or normal.
Targeted therapies are designed to affect cellular proteins or processes that are utilised by the cancer cells.
This allows a high dose to cancer tissues with a relatively low dose to other tissues.
As different proteins are utilised by different cancer types, the targeted therapy drugs are used on a cancer type specific, or even on a patient specific basis.
Although the side effects are often less severe than that seen of cytotoxic chemotherapeutics, life-threatening effects can occur.
Initially, the targeted therapeutics were supposed to be solely selective for one protein.
Now it is clear that there is often a range of protein targets that the drug can bind.
An example target for targeted therapy is the protein produced by the Philadelphia chromosome, a genetic lesion found commonly in chronic myelomonocytic leukemia.
This fusion protein has enzyme activity that can be inhibited by imatinib, a small molecule drug.
Trubion’s product development efforts were focused on three technology pillars: SMIP protein therapeutics, SCORPION protein therapeutics, and TRU-ADhanCe potency enhancing technology for immunopharmaceuticals.SMIP, or small modular immunopharmaceutical, therapeutics are single chain polypeptides comprising one binding domain, one hinge domain and one effector domain designed in an effort to meet predetermined therapeutic specifications for specific diseases.
SMIP therapeutics are mono-specific (they recognize and attach to single antigen targets and initiate biological activity).
Trubion worked on SMIP drug candidates that targeted validated antigens with the same specificity and predictable biological activity as mAbs.SCORPION protein therapeutics are also single chain polypeptides composed of functional domains from naturally occurring proteins.
The difference between SMIP and SCORPION technologies is that SCORPION compounds are multi-specific therapeutics that are capable of targeting two or more antigens simultaneously.TRU-ADhanCe potency enhancing technology was designed to enhance the potency of existing therapies that work through Fc-directed or antibody-directed cellular cytotoxicity, or ADCC.
TRU-ADhanCe technology could be applied late in development to established manufacturing lines and generate candidates with increased ADCC and longer in vivo half lives. 
Silence Therapeutics (AIM:SLN) is a biotechnology company that develops gene therapeutic technology based on RNA interference (RNAi).
They are involved in developmental research of targeted RNAi therapeutics for the treatment of serious diseases.
Formed in 1994 as a publicly traded drug research and development company, Silence Therapeutics has offices in London and Berlin, with its corporate headquarters based at 1 Lyric Square, London. 
Fusion proteins or chimeric proteins (literally, made of parts from different sources) are proteins created through the joining of two or more genes that originally coded for separate proteins.
Translation of this "fusion gene" results in a single or multiple polypeptides with functional properties derived from each of the original proteins.
"Recombinant fusion proteins" are created artificially by recombinant DNA technology for use in biological research or therapeutics.
"Chimeric" or "chimera" usually designate hybrid proteins made of polypeptides having different functions or physico-chemical patterns.
"Chimeric mutant proteins" occur naturally when a complex mutation, such as a chromosomal translocation, tandem duplication, or retrotransposition creates a novel coding sequence containing parts of the coding sequences from two different genes.
Naturally occurring fusion proteins are commonly found in cancer cells, where they may function as oncoproteins.
The bcr-abl fusion protein is a well-known example of an oncogenic fusion protein, and is considered to be the primary oncogenic driver of chronic myelogenous leukemia. 
Clinical Therapeutics is a monthly peer-reviewed medical journal that was established in 1979 and is published by Elsevier.
It is the official journal of the European Association for Clinical Pharmacology and Therapeutics.
The journal covers all aspects of clinical pharmacology and therapeutics.