Metastatic Melanoma: Not Quite Curable…But Getting There


By 2050, the number of deaths due to malignant melanoma in the U.S. could be three times lower than peak levels reached before 1960. Researchers presented the data behind this prediction at the 2017 European Cancer Congress in January.

It is unclear how much of this anticipated decline in deaths can be attributed to the availability of new, effective treatments. However, it is obvious that much-increased awareness of sunlight exposure as the single factor most responsible for the development of skin melanoma has contributed to lower incidence of the disease.

In any case, the armament of treatments available for metastatic melanoma is currently such that this diagnosis has transformed from being almost universally fatal (even just a few years ago) into a being largely treatable. Since 2011, the U.S. Food and Drug Administration (FDA) has approved eight new drugs for melanoma.

Now, the pressing questions are: Why do these drugs not work for all patients? How can doctors select which patients should be treated with different types of drugs (targeted versus immune checkpoint versus intralesional)? And how can doctors identify patients who may benefit from a combination of different drugs?

BRAF-mutant melanoma: targeted drugs 

Getting a positive test for the BRAF V600 tumor mutation is certainly good news for a newly diagnosed melanoma patient. This is because some targeted drugs work very well against such tumors, which account for about 50% of melanomas.

The drugs vemurafenib or dabrafenib, which attack tumors by inhibiting mutant BRAF proteins, are no longer used on their own because combining them with MEK inhibitors (cobimetinib and trametinib, respectively) works so much better. The percentage of patients who respond to combined BRAF/MEK inhibition is about 70% or higher, and durable complete responses were observed in about 19% patients with stage IV or unresectable stage III melanoma in three large clinical trials that tested these combinations. The results of treatment with dabrafenib and trametinib in patients with resectable stage III melanoma were particularly impressive. One hundred percent of these patients had no relapse within the first six months after treatment, compared to just 28% of those treated with standard chemotherapy. All patients had fewer than three metastatic sites.

That last point brings us to an important question: Which stage IV patients with BRAF-mutant (BRAF+) melanoma may need a combined treatment with targeted and immunotherapy (immune checkpoint) drugs?

It is becoming clear that stage IV patients who have fewer, less bulky metastases (lower tumor burden) do much better on BRAF/MEK-targeting drugs. High blood levels of a protein called LDH has long been recognized as a poor prognostic factor in melanoma, and it has not lost its grim significance in the era of targeted and immunotherapy drugs. Patients with high LDH and many metastatic tumors may need a combined treatment with BRAF/MEK inhibitors and immune checkpoint drugs.

So far, combination treatments have proven to be efficacious in patients with high tumor burden. The problem is that combining BRAF/MEK inhibitors with immune checkpoint drugs of the type known as anti-PD-1 increases side effects (toxicity) in quite a dramatic way. The Keynote 022 clinical trial—which combined the anti-PD-1 drug pembrolizumab with dabrafenib and trametinib in a small group of patients—reported that 40% experienced serious side effects (grade 3–4), and close to 30% discontinued treatment. A response rate of 60% was observed but remains to be confirmed.

A very similar rate of side effects was observed in a trial that combined atezolizumab (another immune checkpoint drug of the type known as anti-PD-L1) with vemurafenib and cobimetinib. On a highly positive note, 83% of the patients in this trial responded to the treatment, with 10% going into complete remission. An earlier study of durvalumab (also anti-PD-L1) with dabrafenib and trametinib saw responses in 69% of patients.

Several trials have also addressed the possibility of sequential treatment with two different types of drugs in order to address the problem of toxicity.

Immune checkpoint drugs across the molecular subtypes

Immune checkpoint drugs may also be effective in tumors with mutations other than BRAF, including a mutation in the NRAS gene (NRAS+). Data are being accumulated for patients receiving the FDA-approved immunotherapy drugs nivolumab or pembrolizumab (both anti-PD-1 drugs). It appears that 47% of patients receiving nivolumab survive for three years, and 48–49% of those receiving pembrolizumab survive for 2 years (pembrolizumab data have not yet reached the 3-year point). Combination of nivolumab and ipilimumab (a type of immune checkpoint drug known as an anti-CTLA4 antibody) could eventually produce better results, but at the cost of a much higher toxicity. It is a bit difficult to say if these data are similar for BRAF+ and BRAF-/NRAS+ melanoma patients receiving immune checkpoint drugs, because most patients with BRAF+ cancers receive targeted drugs.

NRAS-mutant melanoma

Patients whose tumors test positive for an NRAS mutation (NRAS+) but not for a BRAF mutation (BRAF-) certainly have fewer treatment options than those whose tumors are BRAF-positive. NRAS mutations are encountered in about 20% of melanomas, and there are no effective targeted drugs for this subgroup. The only targeted drug that has shown promise in NRAS+ melanoma is binimetinib, a MEK inhibitor. In a trial for patients who were either untreated or had not responded to immune checkpoint drugs, binimetinib produced responses in 45% of patients; of those receiving only dacarbazine, a standard chemotherapy, just 9% responded. However, binimetinib prolonged overall survival by just 1.3 months compared to dacarbazine—not exactly an impressive improvement, which is apparently why the manufacturer of binimetinib withdrew its application for FDA approval of the drug.

Other trials are testing immune checkpoint drugs combined with MEK inhibitors for patients whose melanomas have no BRAF mutations (of which a substantial proportion have mutated NRAS). No results of these trials have yet been reported. Meanwhile, a very small study reported a response rate of 45% to combination of atezolizumab (anti-PD-L1) and cobimetinib in BRAF- melanoma patients. Additional trials testing durvalumab or pembrolizumab with trametinib have not posted results yet.

Regardless of specific tumor mutations, much hope lies in the clinical exploration of combinations of drugs that activate the immune system in different ways. Numerous immune checkpoint drugs work by activating the immune system. However, unlike the anti-PD-1 and anti-CTLA4 drugs discussed above, which remove inhibitory signals from the immune system’s T cells so they can attack cancer cells, newer drugs actually activate T cells by binding to positive regulatory proteins on these cells. Other new drugs aim to eliminate inhibitory signals created in the tumor microenvironment, such as those produced by different types of inflammatory cells or regulatory T cells. I would refer the interested reader to this excellent overview of these new drugs, which are now being tested against metastatic melanoma in numerous phase I trials.


Super Patient: Peter Fortenbaugh Faces the Uncertainty of Pioneering Melanoma Treatment


In spring of 2014, Peter Fortenbaugh noticed what appeared to be a tick that had bitten his lower calf. “It turned out not to be a tick, but it didn’t really go away,” he says.

The spot began to grow and bulge, and in October, Peter showed it to his primary care doctor, who referred him to a dermatologist to remove it. At the time, Peter recalls, it did not occur to him that the growth could be serious.

“I was actually very concerned about skin cancer because I spent a lot of time out in the sun sailing,” Peter says. “I put on a tremendous amount of sunscreen and protection, but never on my legs…I never connected the dots.”

However, a biopsy of the growth came back positive for melanoma. Peter, who lives in Palo Alto, California, with his wife and three children, immediately reached out to several doctors in the San Francisco Bay Area, and all had the same advice: “Take it out, take a biopsy.” Continue reading…


How Precision Medicine Could Be A Lifesaver For Kids With Brain Cancer

Excerpt:

“A team of Dana-Farber scientists has released new research with an important message about precision medicine: Sequencing the genes of brain tumors in kids could point to treatments that target their genetic abnormalities and therefore have the best chance of being effective. At least one of those drugs is already on the market, Novartis’ Tafinlar (dabrafenib), approved by the FDA to treat other types of cancer but still readily available to pediatric oncologists who may want to try it in their patients.”

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Melanoma: New Drugs and New Challenges (Part 2 of 2)


Editor’s note: This is part 2 of a 2-part post on the latest research in melanoma. To learn about research into drug combinations for melanoma that may work better than single drugs, check out Melanoma: New Drugs and New Challenges (Part 1 of 2).

As always, the more new treatments become available in melanoma, the more new challenges arise. With eight new drugs approved for melanoma in the last five years, oncologists may sometimes face the difficult choice of what drugs to choose for a patient’s first-line treatment. Immune checkpoint drugs sometimes cause serious side effects, but progress is being made on how to treat these and also how to treat patients with pre-existing autoimmune conditions. New approaches are needed in efforts to prevent recurrence of melanomas diagnosed at earlier stages of disease progression. These and other challenges are discussed below. Continue reading…


Melanoma: New Drugs and New Challenges (Part 1 of 2)


New targeted and immunotherapy drugs have changed the diagnosis of metastatic melanoma from a death sentence into a disease that can potentially be managed and even cured. Nevertheless, these new drugs do not work in all patients, or they may stop working after a transient response. This post (part one of two) will describe ongoing efforts to find drug combinations with higher efficacy than single drugs and decipher the mechanisms underlying drug resistance. Continue reading…


Lung Cancer Highlights from ASCO 2016


This year, the Annual Meeting of the American Society of Clinical Oncology (ASCO) did not produce any truly groundbreaking revelations about new treatments for lung cancer. However, researchers did report quite a few positive findings, and some disappointing ones. I have summarized some of the more prominent presentations below. Continue reading…


3-Year Follow-Up Data for Dabrafenib/Trametinib Confirm Results of Combo in Melanoma

Excerpt:

“Three-year follow-up data from the phase III COMBI-d study was presented at the 2016 ASCO Annual Meeting, revealing impressive overall survival (OS) and progression-free survival (PFS) data for the dabrafenib (Tafinlar) and trametinib (Mekinist) combination therapy for patients with BRAF-mutant metastatic melanoma.

“At the February 15, 2016 data cutoff for the 3-year analysis, 58% of patients remained on therapy. The 3-year PFS rate with the combination was 22% versus 12% with single-agent dabrafenib. The 3-year OS rate was 44% with dabrafenib plus trametinib compared with 32% with dabrafenib alone.

” ‘This is the longest OS follow-up among randomized phase III trials evaluating a BRAF plus MEK inhibitor in patients with BRAF-mutant metastatic melanoma,’ said lead investigator Keith T. Flaherty, MD, Massachusetts General Hospital Cancer Center and Professor of Medicine, Harvard Medical School. ‘With additional follow-up, and now 3-year maturity, dabrafenib plus trametinib continued to show significant benefit over dabrafenib monotherapy, despite crossover.’ ”

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Dabrafenib/Trametinib Combo Highly Effective in BRAF-Mutant NSCLC

Excerpt:

“The combination of dabrafenib (Tafinlar) and trametinib (Mekinist) was highly effective as a treatment for patients with BRAF V600E-mutant non–small cell lung cancer (NSCLC), according to lead investigator David Planchard MD, PhD, who presented the phase II data at the 2016 ASCO Annual Meeting.1 Findings from the study were also concurrently published in Lancet Oncology.2

“The investigator assessed objective response rate (ORR) with the combination was 63% (95% CI, 49-75), which lasted for a median duration of 9.0 months (95% CI, 6.9-18.3). When adding those with stable disease for ≥12 weeks, the overall disease control rate was 79% (95% CI, 66-89). The median progression-free survival (PFS) was 9.7 months (95% CI, 6.9-19.6).

“In addition to the combination cohort, the study also included a single-agent arm that included 78 previously treated patients with metastatic BRAF V600E–mutant NSCLC. In this cohort, the ORR with single-agent dabrafenib was 33% and the median PFS was 5.5 month. Findings from both cohorts of the study have led to breakthrough therapy designations from the FDA for dabrafenib as a single agent and in combination with trametinib.”

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Dabrafenib Active in BRAF-Mutant Metastatic NSCLC

Excerpt:

“Planchard et al found that the BRAF kinase inhibitor dabrafenib (Tafinlar) produced responses in previously treated and untreated patients with BRAF-mutant metastatic non–small cell lung cancer (NSCLC), according to a phase II trial reported in The Lancet Oncology. Activating BRAF V600E mutations are found in approximately 1% to 2% of lung adenocarcinomas.”

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Do you have questions about this story? Let us know in a comment below. If you’re wondering whether this story applies to your own cancer case or a loved one’s, we invite you to use our Ask Cancer Commons service.