Navigation Links
Hit multiple targets for maximum benefit in HER2-positive breast cancer, studies suggest

Combining targeted therapies might be required for maximum anti-tumor activity when treating HER2-positive breast cancers, according to two new studies by Vanderbilt-Ingram Cancer Center (VICC) investigators.

The findings, reported in two papers in the Proceedings of the National Academy of Sciences (PNAS), suggest that upregulation of the HER3 receptor limits the effectiveness of two classes of targeted therapies (HER2- and PI3 kinase-targeted therapies). Therefore targeting HER3 together with these agents should improve their clinical utility.

Around 25 percent of breast cancers have increased expression of the HER2 receptor, which is associated with more aggressive tumors and a poorer prognosis. HER2-targeted therapies like trastuzumab (Herceptin) and lapatinib (Tykerb) are effective in many women with HER2-positive breast tumors.

"But even in patients who respond to HER2-targeted therapies, the clinical response tends to be short-lived and tumors become resistant," said Carlos Arteaga, M.D., professor of Medicine and Cancer Biology, and director of the VICC Breast Cancer Research Program.

HER2 is a member of the EGF receptor family involved in signaling pathways that promote cell growth. HER2 must interact and form complexes with other members of the EGF receptor family, and its main partner in activating pathways that promote tumor growth is HER3. This complex of HER2/HER3 is a potent activator of the PI3K/Akt pathway, the key survival pathway in HER2-positive cancers.

"Based on this evidence, we hypothesized that, for these therapies to have maximum effect, HER3 and its output to the PI3K/Akt pathway must be completely shut down," Arteaga said.

A postdoctoral fellow in Arteaga's laboratory, Joan Garrett, Ph.D., led experiments to examine the effect of the HER2 tyrosine kinase inhibitor, lapatinib, on HER3 expression and activity.

She found that inhibiting HER2 with lapatinib led to an increase in HER3 expression and activation in both HER2-positive human breast tumors and cell lines. Inhibiting HER3 in HER2-positive breast cancers growing in mice made tumor cells markedly more sensitive to lapatinib. Additionally, blocking both HER2 and HER3 was more effective at inhibiting the activity of PI3K/Akt pathway than either inhibitor alone.

Those results, published March 7 in PNAS, show that upregulation of HER3 limits the effectiveness of HER2-targeted therapies and that a combination of drugs that target both HER2 and HER3 should be considered for optimal clinical benefit.

Since PI3K/Akt is the key pro-survival signaling pathway downstream of HER2, the investigators also examined the utility of inhibitors of PI3K in HER2-positive breast cancer cells.

Those experiments, led by postdoctoral fellow Anindita Chakrabarty, Ph.D., and published Feb. 28 also in PNAS, showed a similar upregulation of HER3 in response to treatment with a PI3K inhibitor currently in clinical development. In turn, this compensatory upregulation of HER3 partially reactivated the PI3K/Akt pathway and limited the action of the PI3K inhibitor.

"This shows that therapeutic use of PI3K inhibitors would be limited if used as single agents in HER2-positive cancers. These results have implications for other cancers treated with this class of drugs," Arteaga said. However, he notes PI3K inhibitors might have clinical merit when used in combination with HER2-HER3 antagonists.

Since both HER3 inhibitors and PI3K inhibitors are now in clinical development, "these studies provide a scientific rationale for how a combination of the new drugs with HER2-targeted therapies might be used to provide better results for many patients with breast cancer," Arteaga said.


Contact: Melissa Marino
Vanderbilt University Medical Center

Related medicine news :

1. Multiple sclerosis blocked in mouse model
2. Psoriasis medication rises hope in the fight against multiple sclerosis
3. How sunlight may reduce the severity of multiple sclerosis
4. Multiple childbirth linked to increased risk of rare, aggressive triple-negative breast cancer
5. Wayne State University researchers publish results settling multiple sclerosis debate
6. VCU Massey first to combine targeted agents to kill multiple myeloma cells
7. Most ADHD Kids Have Multiple Conditions, Study Says
8. More than allergies: Histamine may be a possible drug target for multiple sclerosis
9. Tiny RNA shown to cause multiple types of leukemia
10. Laboratory studies show promise for new multiple sclerosis treatment
11. Common for patients to undergo multiple cardiac imaging tests, with high cumulative radiation dose
Post Your Comments:
(Date:6/27/2016)... , ... June 27, 2016 , ... ... mental health professionals, announced today its affiliation with Tennessee Counseling Association. ... to the network of the Tennessee Counseling Association, adding exclusive benefits and promotional ...
(Date:6/26/2016)... (PRWEB) , ... June 26, 2016 , ... On June ... sponsor of the 2016 Cereal Festival and World’s Longest Breakfast Table in Battle Creek, ... of the city’s history as home to some of the world’s leading providers of ...
(Date:6/25/2016)... Washington, D.C. (PRWEB) , ... June 25, 2016 ... ... will discuss health policy issues and applications at AcademyHealth’s Annual Research Meeting June ... share their work on several important health care topics including advance care planning, ...
(Date:6/25/2016)... ... June 25, 2016 , ... As a lifelong Southern ... Laude and his M.D from the David Geffen School of Medicine at UCLA. He ... Los Angeles to complete his fellowship in hematology/oncology at the UCLA-Olive View-Cedars Sinai program ...
(Date:6/24/2016)... ... 24, 2016 , ... Those who have experienced traumatic events may suffer from ... avenues, such as drug or alcohol abuse, as a coping mechanism. To avoid this ... coping following a traumatic event. , Trauma sufferers tend to feel a range of ...
Breaking Medicine News(10 mins):
(Date:6/24/2016)... KNOXVILLE, Tenn. , June 24, 2016 /PRNewswire/ ... market providing less invasive and more durable cerebrospinal ... million in funding.  The Series-A funding is led ... the Lighthouse Fund, and other private investors.  Arkis, ... less-invasive neurosurgical instrumentation and the market release of ...
(Date:6/23/2016)... -- Any dentist who has made an implant supported denture ... of them do not even offer this as a viable ... costs involved. And those who ARE able to offer that ... cost that the majority of today,s patients would not be ... , founder of Dental Evolutions Inc. and inventor of Implanova ...
(Date:6/23/2016)... Roche (SIX: RO, ROG; OTCQX: RHHBY) announced that it ... (procalcitonin) assay as a dedicated testing solution for people ... Roche is the first IVD company in the U.S ... assessment and management. PCT is a sepsis-specific ... blood can aid clinicians in assessing the risk of ...
Breaking Medicine Technology: