Zosia Chustecka

June 01, 2014

Chicago — Sunday afternoon is the plenary session here at the 2014 Annual Meeting of the American Society of Clinical Oncology® (ASCO), where highly anticipated results will be presented in breast, prostate, and colorectal cancer. A quick summary of the results follows, but please check back later in the day for detailed coverage and reactions to the new findings.

"Today's results answer critical questions faced by people with cancer and their doctors every day. There is no doubt that patients will live longer and better because of these studies," commented ASCO president Clifford Hudis, MD, chief of breast cancer medicine at the Memorial Sloan-Kettering Cancer Center in New York City.

Young Women With Breast Cancer

One of the breast cancer presentations focuses on young women with hormone-sensitive early disease (abstract LBA1) and reports a joint analysis of the TEXT and SOFT trials, conducted in a total of 5738 premenopausal women.

For years, tamoxifen has been the gold standard for preventing breast cancer recurrences in premenopausal women, but the new results show that the aromatase inhibitor exemestane, together with ovarian function suppression, offers "a valid alternative," say the researchers.

In fact, exemestane appears to be more effective than tamoxifen, when both are used in combination with ovarian function suppression, as it resulted in a greater reduction in the risk for breast cancer recurrence. But the researchers caution that longer follow-up is needed to assess survival, as well as long-term adverse effects and fertility.

One issue is that ovarian function suppression is not usually combined with tamoxifen in clinical practice in the United States; it is usually used alone. However, ovarian function suppression is necessary for exemestane to work, so in these trials both drugs were combined with ovarian function suppression, which was achieved by surgical oophorectomy, ovarian irradiation, or the drug triptorelin. Obviously, these options affect future fertility, so the question of whether the young woman being treated would like to have children in the future is an important consideration.

The other breast cancer presentation focuses on HER2-positive disease and reports results from the ALTTO trial (abstract LBA4), in which women with early-stage disease had already undergone surgery and were then treated with HER2-targeted agents, as well as chemotherapy.

Surprisingly, adding lapatinib (Tykerb) to trastuzumab (Herceptin) did not improve significantly on the benefits seen with trastuzumab alone, even though an added benefit had been seen previously in an earlier trial that used the combination prior to surgery.

"A key lesson of this trial is that we need robust clinical trials in specific disease settings to fully assess and understand the value of new treatment regimens," commented senior author Edith Perez, MD, deputy director at large at the Mayo Clinic Cancer Center in Jacksonville, Florida.

New Treatment Paradigm in Prostate Cancer

The prostate cancer trial (abstract LBA2) being presented at the plenary session offers a new treatment paradigm of adding chemotherapy early on in the disease, and using it in combination with androgen-deprivation therapy (ADT) in men with newly diagnosed hormone-sensitive metastatic disease.

ADT has been the standard first-line therapy in this clinical situation for more than 50 years, and typically chemotherapy is used in prostate cancer only when the disease becomes resistant and progresses despite ADT.

In this clinical trial, known as E3805, chemotherapy (docetaxel) was used together with ADT from the outset in one group of patients, and was shown to extend survival by 10 months when compared with ADT alone.

"These results demonstrate how we can use 'old tools' in new, more powerful ways to improve and extend patients' lives." Dr. Hudis commented in a statement, adding that both docetaxel and ADT are available as generics.

Also being presented today is another study in prostate cancer, which suggests that it may be safe to delay restarting ADT in men who show biochemical recurrence (i.e., rising levels of prostate-specific antigen). There was no significant difference in 5-year or estimated 10-year survival rates between men who started back on ADT immediately after biochemical recurrence and those who waited for up to 2 years (abstract 5003).

Reassuring Results in Colorectal Cancer

The colorectal cancer trial (abstract LBA3) presented at the plenary session offers reassurance to patients and physicians who are having to decide on which treatment regimen to choose.

The trial was conducted in patients with metastatic colorectal cancer and no KRAS mutations. The results show that there is little difference between 2 targeted antibody products — bevacizumab (Avastin) and cetuximab (Erbitux) — or between 2 chemotherapy regimens — FOLFOX (oxaliplatin/5-fluorouracil/leucovorin) and FOLFIRI (irinotecan/5-fluorouracil/leucovorin).

The median overall survival was about 29 months with any combination of antibody and chemotherapy.

"Our findings clearly show that the 2 antibodies — with either FOLFOX or FOLFIRI — are both acceptable and similarly effective," commented lead investigator Alan Venook, MD, from the University of California, San Francisco. He noted that about 75% of patients with metastatic colorectal cancer in the United States receive bevacizumab, but these results show that cetuximab is "also a good option for a subset of patients" (i.e., those who have been tested and found negative for KRAS mutations).

First Drug Therapy for Rare Joint Disorder

Also happening today is the presentation (abstract 10503) about a new targeted therapy (PLX3397, Plexxikon) that could offer the first drug treatment for pigmented villonodular synovitis. This is a rare disorder that results in bone destruction and repeated joint bleeding. It is currently treated by surgery and joint replacement, but it eventually advances to a point where a patient is no longer operable.

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