MGI^SM (Molecular Grade Index)

Molecular tumor grading to improve breast cancer management

MGI is a 5-gene expression index used to stratify breast cancer patients into low or high risk of recurrence.

• Allows quantitative and objective molecular assessment of tumor grade and proliferation rate.
• Discriminates between tumor grades 1 and 3 and reclassifies grade 2 tumors into two distinct groups:¹ — Low MGI – low risk of recurrence, Grade 1-like
— High MGI – high risk of recurrence, Grade 3-like

Patients with ER-positive, lymph node-negative breast cancer treated with endocrine therapy or combined chemoendocrine therapy (n = 93).

MGI is prognostic for estrogen receptor (ER) positive patients regardless of nodal status.¹ The five genes of MGI are preferentially expressed in:²

• High grade > low grade tumors
• Invasive tumors > ductal carcinoma in situ (DCIS)
• Different phases and processes of the cell cycle

In one study, MGI was associated with Pathological Complete Response (pCR) from chemotherapy.³

• Approximately 20% of high MGI tumors had a pCR
• No tumors with a low MGI (~55%) had a pCR

Stratification using MGI

• MGI eliminates intermediate grade
• MGI reclassifies grade 2 tumors into grade 1-like and grade 3-like tumors

Patient cohort of 239 stage I-III patients with ER-positive primary breast cancer treated at the Massachusetts General Hospital from 1991-1999. Following diagnosis, patients received treatment as per standards of care at that time, including chemotherapy plus endocrine therapy or endocrine therapy alone.

Assay information

• Real-time RT-PCR assay
• Compatible with formalin-fixed paraffin embedded samples
• Patent pending

Clinical validations

A collaborative study evaluating the MGI have been completed and published in peer reviewed scientific journals:

• Harvard Medical School/MGH, Boston, MA.¹

References:
1. Ma X-J, Salunga R, Dahiya S, et al: A five-gene molecular grade index and HOXB13:IL17BR are complementary prognostic factors in early stage breast cancer. Clin Cancer Res. 14(9): 2601-2608, May 1, 2008.
2. Whitfield ML, Sherlock G, Saldanha AJ, et al. Identification of genes periodically expressed in the human cell cycle and their expression in tumors. Mol Biol Cell., 13:1977-2000. 2002. Also http://genome-www.stanford.edu/Human-CellCycle/Hela/index.shtml
3. Raw data from Hess KR, Anderson K, Symmans WF, et al. Pharmacogenomic predictor of sensitivity to preoperative chemotherapy with paclitaxel and fluorouracil, doxorubicin, and cyclophosphamide in breast cancer. J Clin Oncol., 24:4236-4244, 2006.