Mouse avatars, or avatar

mice A mouse ( : mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus' ...

, refers to an experimental method employed to identify the best chemotherapeutic choice for a particular cancer patient.

Origin

The method was originally employed to treat cancer patients by Dr. Manuel Hidalgo (Spanish National Cancer Research Center in Madrid).Hidalgo M, Bruckheimer E, Rajeshkumar NV, et al: A pilot clinical study of treatment guided by personalized tumorgrafts in patients with advanced cancer. Mol Cancer Ther 10:1311-6, 2011 The name mouse avatar or avatar mice was originally coined by the Spanish National Cancer Research Center and was subsequently popularized by the journals '' Nature'' and '' Science'', the

Mayo Clinic The Mayo Clinic () is a nonprofit American academic medical center focused on integrated health care, education, and research. It employs over 4,500 physicians and scientists, along with another 58,400 administrative and allied health staff, ...

and The New York Times among others.

Method

Generally, mouse avatars involve three steps, as follows:

Step one

The tumor is obtained by

surgical resection Segmental resection (or segmentectomy) is a surgical procedure to remove part of an organ or gland, as a sub-type of a resection, which might involve removing the whole body part. It may also be used to remove a tumor and normal tissue around i ...

. This may cure the patient. The tumor however may regrow, at the same or at a distant location ( metastasis), a process that usually entails several months. If this happens, the avatar mice may guide the oncologist to choose the most efficient chemotherapeutic treatment.

Step two

Fresh pieces of the tumor are implanted into mice (these are the so-called "first-generation" avatar mice). The implants can be at the same location where the tumor was formed in the patient, in which case are known as orthotopic xenografts or, most commonly, at a different location, generally subcutaneous, in which case are called heterotopic xenografts. If necessary, the tumors from the first-generation avatar mice can be extracted, divided into pieces, and implanted again in multiple avatar mice ("second generation"). This process can be repeated several times to obtain a large number of avatar mice from a single patient. In general, 3–4 generations are needed to obtain enough avatar mice from a single patient.

Step three

Once the desired number of avatar mice has been achieved, the mice are treated with the several available options of chemotherapy (single agents or combined agents). The response of the tumors in the avatar mice to the various chemotherapeutic regimens is examined and the most efficient one is chosen. The whole process usually takes several months. If the tumor of the patient recurs, then the oncologist can decide which chemotherapeutic treatment to apply based on the response of the avatar mice that carried the original tumor of the patient.

In practice

The therapeutic benefits of the avatar mice have been demonstrated in pilot studies by Dr. Manuel Hidalgo with

pancreatic cancer Pancreatic cancer arises when cell (biology), cells in the pancreas, a glandular organ behind the stomach, begin to multiply out of control and form a Neoplasm, mass. These cancerous cells have the malignant, ability to invade other parts of t ...

patients as well as with other cancers.Villarroel MC, Rajeshkumar NV, Garrido-Laguna I, et al: Personalizing cancer treatment in the age of global genomic analyses: PALB2 gene mutations and the response to DNA damaging agents in pancreatic cancer. Mol Cancer Ther 10:3-8, 2011

References

{{Reflist Oncology