The past 12 months have been anything but boring for Micromet’s shareholders (MITI). Last summer, Micromet’s stock climbed to $7 following excellent clinical data (discussed here) and a landmark publication in Science Magazine (discussed here), but since then the company has lost half of its value. Volatile trading is quite standard for small, cash burning biotechnology companies, however, Micromet’s case was particularly frustrating.
Micromet invented a new class of antibodies it calls BiTE (Bispecific T-Cell Engager) antibodies. Unlike conventional antibodies, BiTE antibodies bind two targets, the first target is presented on a cancer cell and the second is presented on an immune cell. The simultaneous binding of both cells by the BiTE antibody can redirect the immune cell to attack the cancer cell, thus exploiting the body’s natural immune mechanisms to fight cancer. Conceptually, a BiTE antibody is similar to cancer vaccines, which also aim at producing an immune response against tumors. Despite a history of failures in the field of immunostimulating antibodies, it looks like Micromet has found the right formula.
Chemotherapeutic Drugs in The Clinic – Competitors or Potential Partners?
Obviously, SGN-33 was not directly compared to any other agent, so insight gained from comparing SGN-33 to other agents from different clinical trials is far from being conclusive. In addition, a comparison of a naked antibody (that will likely be given in combination with other drugs), to other chemo and combination regimens is not a fair one. Nevertheless, these comparisons are the only means researchers and investors alike have when evaluating the prospects of SGN-33.
The efficacy/safety ratio of SGN-33 is very impressive when compared to available treatments as well as other treatments currently evaluated in clinical trials. The cornerstone treatment for older AML patients is low-dose araC which has less than 20% complete response rate as a single agent (compared with 29% for SGN-33 in the current trial). araC is typically administered with other agents and is currently evaluated in combination with some novel drug candidates. These combinations result in a much better response rate, in the range of 30-60% among a variety of patient populations.