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…


Immunotherapy, MEK Inhibitor Combo Effective for BRAF Wild-Type Melanoma

Excerpt:

“The combination of atezolizumab (Tecentriq) and cobimetinib (Cotellic) may lead to a higher overall response (ORR) and a longer progression-free survival (PFS) than either agent alone in patients with metastatic melanoma, according to findings presented at the 2016 Society for Melanoma Research (SMR) Annual Meeting.

“The findings were part of a phase Ib dose-escalation and dose-expansion study, which looked at the PD-L1 inhibitor and MEK inhibitor together in advanced solid tumors. Data on a cohort of 22 patients with ocular melanoma (n = 2) and non-ocular melanoma (n = 20) was presented at the meeting. Among patients in the non-ocular cohort, the ORR was 45% and the disease-control rate (complete response, partial response, and stable disease) was 75%. Median PFS was 12 months (95% CI, 2.8-16.7).”

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Atezolizumab Combos Highly Effective for Advanced Melanoma

Excerpt:

“The addition of the PD-L1 inhibitor atezolizumab (Tecentriq) to the MEK inhibitor cobimetinib (Cotellic) and the BRAF inhibitor vemurafenib (Zelboraf) induced a high response rate for patients with BRAF-mutant unresectable melanoma, according to findings from a phase Ib study presented at the 2016 Society for Melanoma Research Annual Meeting.

“At the data cutoff of June 15, 2016, 30 patients had received ≥1 dose of atezolizumab. The response rate with the triplet was 83%, which included 3 complete responses (10%) and 21 partial responses. Overall, 29 of the 30 patients were evaluable for response, with just 1 patient experiencing primary progressive disease. At the time of the analysis, median duration of response and progression-free survival were not yet reached.”

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Final OS Analysis Confirms Cobimetinib/Vemurafenib Benefit in Melanoma

Excerpt:

“Combination therapy with cobimetinib (Cotellic) and vemurafenib (Zelboraf) reduced the risk of death by 30% compared with vemurafenib alone in patients with BRAF-positive advanced melanoma, according to the final survival analysis of the phase III coBRIM study that has now been published in The Lancet Oncology.

“The targeted combination improved median overall survival (OS) by 4.9 months versus single-agent vemurafenib (HR, 0.70; 95% CI, 0.55-0.90; P = .005). The OS rates for the combination at 1 and 2 years were 74.5% and 48.3%, respectively.

“ ‘Melanoma is one of the few cancers that has increased in incidence over the past 30 years, and until recently, people with advanced forms of the disease have had few treatment options. Five years ago, the survival of people with advanced melanoma was measured in months, and now we have medicines that are helping people live years,’ Josina Reddy, MD, PhD, senior group medical director at Genentech, the company that manufactures the combination, said in an interview with OncLive.”

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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…


Cobimetinib, Vemurafenib Improved Survival in BRAF V600–Mutated Melanoma

Excerpt:

“Combination treatment with cobimetinib and vemurafenib resulted in significantly improved overall and progression-free survival in patients with previously untreated BRAF V600mutated advanced melanoma, according to updated efficacy results of the coBRIM trial published in Lancet Oncology.

“ ‘Patients treated with the combination of cobimetinib and vemurafenib achieved a higher objective response, longer progression-free survival, and longer overall survival compared with patients treated with vemurafenib alone,’ wrote researchers led by Paolo A. Ascierto, MD, of the Istituto Nazionale Tumori Fondazione G Pascale in Naples, Italy. ‘The combination of cobimetinib and vemurafenib was recently approved by the US Food and Drug Administration and the European Medicines Agency for the treatment of advanced BRAF V600mutant melanoma and represents a new standard of treatment for patients with this disease.’ ”

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Vemurafenib/Cobimetinib Combo for Melanoma Approved by FDA

“The FDA has approved a combination of vemurafenib (Zelboraf) and cobimetinib (Cotellic) to treat patients with metastatic or unresectable BRAF V600E/K mutation-positive melanoma. The approval was based on based on an extension in progression-free survival (PFS) in the phase III coBRIM study.

“In the data submitted to the FDA, the median PFS with the combination was 12.3 versus 7.2 months with vemurafenib plus placebo (HR, 0.58; 95% CI, 0.46-0.72). PFS was the primary endpoint of the study with secondary outcome measures including overall survival (OS), objective response rate (ORR), duration of response, and safety.”


Exelixis Announces Positive Overall Survival Results from Phase 3 Pivotal Trial of Cobimetinib in Combination with Vemurafenib in Patients with BRAF V600 Mutation-Positive Advanced Melanoma

“Exelixis, Inc.EXEL, -1.02% today announced positive overall survival (OS) results from coBRIM, the phase 3 pivotal trial evaluating cobimetinib, a specific MEK inhibitor discovered by Exelixis, in combination with vemurafenib in previously untreated patients with unresectable locally advanced or metastatic melanoma carrying a BRAF V600 mutation. Exelixis’ collaborator Genentech, a member of the Roche Group, informed the company that coBRIM met its secondary endpoint of demonstrating a statistically significant and clinically meaningful increase in overall survival for patients receiving the combination of cobimetinib and vemurafenib, as compared to vemurafenib monotherapy. Ongoing study monitoring did not identify any new safety signals. Long-term safety data are expected later this year. These data will be the subject of a presentation at an upcoming medical meeting.”