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New Promise Shown in Treatments for Melanoma, Breast Cancer

June 6, 2011 at 12:00 AM EST
Two studies have doctors energized about the prospects for treating people with advanced cases of deadly skin cancer and the prospects for a new breast cancer drug. Judy Woodruff discusses the latest developments with Dr. George Sledge of The American Society of Clinical Oncology.
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TRANSCRIPT

GWEN IFILL: Next, some hopeful news in the field of cancer treatment.

Judy Woodruff has our story.

JUDY WOODRUFF: Astounding and unprecedented aren’t words you often hear from the country’s leading cancer specialists, but two studies released this weekend have oncologists excited about the prospects of treatment options for people with advanced cases of the deadly skin cancer melanoma.

Two new drugs, with two new approaches, have been found to help combat the disease. One goes after a gene mutation that accelerates tumor growth. The other stimulates the immune system to fight the cancer. Eighty-four percent of those taking the gene-targeting drug were still alive after six months, reducing the death risk by 63 percent. Twenty-one percent of those taking the immune-boosting drug were alive after three years, compared to just 12 percent on chemotherapy or a placebo.

In other cancer news, a drug used to prevent recurrences of breast cancer was also found to reduce the risk of it occurring in the first place. And screening for ovarian cancer was found not to reduce the risk of dying from the disease.

Well, all of this was released at the American Society of Clinical Oncology‘s annual meeting in Chicago.

And to tell us more is that group’s outgoing president. He’s Dr. George Sledge.

Dr. Sledge, thank you for being with us.

And let me ask you first about the melanoma treatments. Do these qualify as a breakthrough?

DR. GEORGE SLEDGE, American Society of Clinical Oncology: These — Judy, these are genuinely exciting.

I have been in this field for 30 years. During that period, the standard therapy for melanoma has been a drug that is both toxic and relatively ineffective, a chemotherapy drug called dacarbazine. It has a response rate of about 5 percent in patients with advanced disease.

One of the two drugs that you mentioned, the drug that is the inhibitor of the growth factor pathway, gives you a response rate of 48 percent. So it’s nine to 10 times as effective at shrinking the tumors compared to the older therapy, so a genuine advance and genuine excitement in the field over this.

JUDY WOODRUFF: What is so different, Dr. Sledge, about the way these drugs go after the cancer?

DR. GEORGE SLEDGE: Well, our older therapies were non-specific therapies. They basically targeted cell division in the cancer cell.

The new therapies are true targeted therapies. So the BRAF inhibitor, drug that inhibits the growth factor pathway, we actually can measure a very specific mutation in patients who have melanomas in their skin. If that mutation is there, we then apply the drug that targets that mutation — total change from how we did business 10 years ago, part of the emerging trend in cancer medicine of going after very specific molecular targets.

JUDY WOODRUFF: And is one of these two approaches more impressive than the other?

DR. GEORGE SLEDGE: Well, we don’t know yet. We don’t have a head-to-head comparison.

Oncologists, when they have two new drugs that improve survival — and both of these drugs improve survival — probably the first thing we are going to do is to combine them to see if we get even better improvement. Neither of these drugs will — in and of itself, is likely to cure metastatic melanoma, so we will want to do novel combinations with them to see if we do — will do better.

We will want to move these drugs up front to patients with earlier-stage disease to see whether or not something that improves survival on the one hand may actually improve the cure rate when used in an earlier stage of patients.

JUDY WOODRUFF: And why does it — why has it taken so long to find these approaches?

DR. GEORGE SLEDGE: Well, very simply, we just didn’t understand the biology of melanoma until very recently.

The mutation, for instance, that we’re going after with this new drug was one that 10, 15 years ago, we didn’t know existed in melanoma. This is part of the payoff for the nation’s investment in cancer research over the past several decades.

We’re now beginning to understand, for just about every cancer, what makes these cancers tick, and therefore, how we can interrupt the growth of these cancers.

JUDY WOODRUFF: And as you suggested a minute ago, Dr. Sledge, and I was reading today, not everyone can benefit — with melanoma can benefit from this. There are limits to the — to the benefits that it has.

Explain who can and who can’t expect to — to try this drug.

DR. GEORGE SLEDGE: Well, for the drug that interferes with the growth factor receptor pathway, there’s a very specific mutation in the protein called BRAF. BRAF is one of the drivers of growth in metastatic melanoma.

Only about 45 to 50 percent of patients have this mutation. We can measure the mutation in the tumors of patients with melanoma. If you have the mutation, you’re a candidate for the drug. If you don’t have the mutation — and this is half the patients with melanoma — the drug simply doesn’t work.

JUDY WOODRUFF: All right, let me turn you now, Dr. Sledge, to this breast cancer finding.

The drug is called Aromasin, stopping the production of estrogen, which we know fuels tumor growth. Help us understand how that works and why that’s important.

DR. GEORGE SLEDGE: So, this is a drug that’s been around for a while. It was developed in the mid-1990s. We have used it to treat both metastatic breast cancer and early-stage breast cancer to prevent recurrence in early-stage disease.

It’s a drug that works in women after — who have gone through the menopause by lowering estrogen levels in their blood. Now, we know that many breast cancers develop as a result of chronic estrogen exposure. So, if we take a group of women who we know to be at high risk for developing breast cancer, and give women this drug, for those high-risk women, it roughly cuts in half their risk of developing a new breast cancer.

JUDY WOODRUFF: But — but what’s new here is that you have now learned that women who have had not had breast cancer before can benefit from this.

DR. GEORGE SLEDGE: That’s absolutely correct.

This is not a treatment for breast cancer. This is a preventative agent now for breast cancer.

JUDY WOODRUFF: All right.

And, finally, let me ask you about — I guess this news is less hopeful with regard to ovarian cancer. Explain that to us.

DR. GEORGE SLEDGE: Well, we had hoped for many years that, by using blood tests that can detect ovarian cancer, or by using ultrasound to look at the ovaries of women with — with — who are at high risk for ovarian cancer, that we might be able to detect these cancers early.

So, in a government-sponsored trial, we took a large group of women and either did a screening with the blood test, what’s called a CA-125, along with ultrasound screening, or — or neither of those, and then followed the women for a prolonged period of time, up to 13 years in this study. And, unfortunately, the results of this trial are that the extensive screening doesn’t improve the woman’s likelihood — doesn’t lower a woman’s likelihood of dying of ovarian cancer.

I think what this says is back to the drawing board. These are fairly crude tools. We need tools that are more precise, that detect the cancer at an earlier point in time, or alternatively, we just simply need better treatments for ovarian cancer once it develops.

JUDY WOODRUFF: So, what does that say about the diagnosis for ovarian cancer?

DR. GEORGE SLEDGE: Well, it still represents a very dangerous disease.

Now, there were other studies at the meeting that were looking at new agents for the treatment of ovarian cancer. And one in — one in particular in two separate studies was shown to significantly prolong the period that women remained in remission with overt ovarian cancer.

But we clearly need to get better at finding these cancers earlier and treating them before they can reach a point that they threaten the life of the woman with the disease.

JUDY WOODRUFF: But, to sum up, it sounds as if there is some — certainly some excitement about what came out of this meeting with regard to melanoma.

DR. GEORGE SLEDGE: Absolutely, real progress on that front.

JUDY WOODRUFF: All right.

Dr. George Sledge, we thank you very much for being with us.

DR. GEORGE SLEDGE: My pleasure.