Trastuzumab emtansine (ado-trastuzumab emtansine, trade name Kadcyla) is a combination between a monoclonal antibody and a small-molecule drug. Each molecule of trastuzumab emtansine consists of a single trastuzumab molecule with several molecules of DM1, a cytotoxic maytansinoid, attached. SMCC, or succinimidyl trans-4-(maleimidylmethyl)cyclohexane-1-carboxylate, is a heterobifunctional crosslinker, a type of chemical reagent that contains two reactive functional groups, a succinimide ester and a maleimide. The succinimide group of SMCC reacts with the free amino group of a lysine residue in the trastuzumab molecule and the maleimide moiety of SMCC links to the free sulfhydryl group of DM1, forming a covalent bond between the antibody and the DM1. Each trastuzumab molecule may be linked to zero to eight DM1 molecules (3.5 on average). Trastuzumab emtansine is an antibody-drug conjugate consisting of the recombinant anti-epidermal growth factor receptor 2 (HER2) monoclonal antibody trastuzumab conjugated to the maytansinoid DM1. The trastuzumab moiety of this ADC binds to HER2 on tumor cell surface surfaces; upon internalization, the DM1 moiety is released and binds to tubulin, thereby disrupting microtubule assembly/disassembly dynamics and inhibiting cell division and the proliferation of cancer cells that overexpress HER2. Linkage of antibody and drug through a nonreducible linker has been reported to contribute to the improved efficacy and reduced toxicity of this ADC compared to similar ADCs constructed with reducible linkers. Trastuzumab emtansine is used for the treatment of patients with HER2-positive, metastatic breast cancer who previously received rastuzumab and a taxane, separately or in combination. Patients should have either: received prior therapy for metastatic disease, or developed disease recurrence during or within six months of completing adjuvant therapy. Ado-trastuzumab emtansine is marketed under the brand name Kadcyla and is indicated for use in HER2-positive, metastatic breast cancer patients who have already used taxane and/or trastuzumab for metastatic disease or had their cancer recur within 6 months of adjuvant treatment. The FDA label has two precautions. First that ado-trastuzumab emtansine and trastuzumab cannot be interchanged. Second that there is a black box warning of serious side effects such as hepatotoxicity, embryo-fetal toxicity, and cardiac toxicity.

Linaclotide (marketed under the trade name Linzess and Constella) is a peptide agonist of the guanylate cyclase 2C (GC-C). Once linaclotide and its active metabolite binds to GC-C, it has local effect on the luminal surface of the intestinal epithelium. Activation of GC-C by linaclotide results in the intra- and extracellular increase of cyclic guanosine monophosphate concentrations (cGMP). This elevation of cGMP levels stimulates the secretion of chloride and bicarbonate into the intestinal lumen via activation of cystic fibrosis transmembrane conductance regulator (CFTR) ion channel. The metabolite of linaclotide MM-419447 (CCEYCCNPACTGC) contributes to the pharmacologic effects of linaclotide. Ultimately, linaclotide helps patients with IBS (especially with constipation) as GI transit is accelerated and the release of intestinal fluid is increased. In animal models, a decrease in visceral pain after administration of linaclotide may be observed. A decrease in the activity of pain-sensing nerves occurs as a result of an increase in extracellular cGMP. It was approved by the FDA in August 2012 for the treatment of chronic idiopathic constipation and irritable bowel syndrome with constipation (IBS-C) in adults.

Teduglutide is a glucagon-like peptide-2 (GLP-2) analogue. It is made up of 33 amino acids and is manufactured using a strain of Escherichia coli modified by recombinant DNA technology. Teduglutide differs from GLP-2 by one amino acid (alanine is substituted by glycine). The significance of this substitution is that teduglutide is longer acting than endogenous GLP-2 as it is more resistant to proteolysis from dipeptidyl peptidase-4. GLP-2 is known to increase intestinal and portal blood flow, and inhibit gastric acid secretion. Teduglutide binds to the glucagon-like peptide-2 receptors located in intestinal subpopulations of enteroendocrine cells, subepithelial myofibroblasts and enteric neurons of the submucosal and myenteric plexus. Activation of these receptors results in the local release of multiple mediators including insulin-like growth factor (IGF)-1, nitric oxide and keratinocyte growth factor (KGF). FDA approved on December 21, 2012. In Europe it has been granted orphan drug status and is marketed under the brand Revestive by Nycomed. It works by promoting mucosal growth and possibly restoring gastric emptying and secretion.