Amorphous Treatment Paradigm in Melanoma Provides Countless Options

Rene Gonzalez, MD

Jeffrey S. Weber, MD, PhD

As new information regarding the efficacy of targeted and immunotherapeutic approaches emerge, the standard of care for patients with melanoma becomes slightly more altered.

Use of Immunotherapies and Sequencing in Advanced Melanoma

For BRAF-positive patients with metastatic or unresectable melanoma, the standard of care includes a BRAF inhibitor with a MEK inhibitor. For patients with or without BRAF mutations, there are immunotherapeutic options in frontline and resistant disease settings. Still, questions remain on the optimal sequencing and/or combinations of both targeted agents and immunotherapies. In the same train of thought lies a question for BRAF-mutant diseases and when it is appropriate to switch from a targeted approach to an immunotherapeutic one.

In December 2015, the PD-1 inhibitor pembrolizumab gained indications as a frontline treatment in patients with advanced melanoma, regardless of BRAF status, and another for patients refractory to the CTLA-4 inhibitor ipilimumab1. The FDA also recently approved the PD-1 immune checkpoint inhibitor nivolumab to include it in combination as a frontline treatment for patients with BRAF wild-type advanced melanoma.2

Jeffrey S. Weber, MD, PhD, said the “tail of the curve” with ipilimumab, nivolumab, and pembrolizumab, shows a long-lasting treatment effect with these immunotherapies.

“If you get beyond 3 years in remission, partial, complete, or with stable disease, you’re probably going to stay there for a long time ... I’ve been treating patients with ipilimumab for 14 years and I occasionally get an e-mail, or a letter, or a postcard from a patient I treated 13, 14 years ago when I was in Los Angeles, and they’re alive and doing well,” Weber said, adding he feels as though

Optimal sequencing with anti-PD-1 and anti-CTLA-4 antibodies remains unclear. Despite initial approvals for pembrolizumab and nivolumab as second-line therapies post-ipilimumab, there is evidence that PD-1 inhibition upfront may be a better approach.

Jason J. Luke, MD, referred to theCheckMate-064 data, which showed an objective response rate (ORR) by modified RECIST criteria at week 25 of 41.2% in patients who received nivolumab followed by ipilimumab. This contrasts the 20.0% in patients receiving the 2 therapies in the opposite sequence.3

“I think there are pretty good data now that suggest that anti-PD-1 antibody, absent other particular caveats, really ought to be the frontline therapy. I prefer to use a single-agent anti-PD-1 antibody upfront because it’s robust, you get response rates, you get disease control, and you don’t have this massive increase in toxicity profile,” Luke stated.

Rene Gonzalez, MD, expressed an opposing perspective.

“I would quibble a little bit with that for two reasons,” he said. “One, is we have the really long tail with ipilimumab that nothing comes even close to, IL-2 maybe. But, the other thing is we don’t know how long to treat people with PD-1 [inhibitors]. One of the beauties of ipilimumab is you get your 4 doses, and you’re done.”

Weber, lead investigator on the CheckMate-064 trial, also supported using a PD-1 inhibitor prior to the CTLA-4 inhibitor.

Rene Gonzalez, MD

Rene Gonzalez, MD

Combination Strategies

“They all got the same therapy. Very few patients dropped out,” added Weber. “The only difference was the sequence.”

Data from CheckMate-069, which showed a 60% reduction in the risk of progression or death with the combination of nivolumab and ipilimumab versus ipilimumab alone, led to the approval of the combination in patients with BRAF V600 wild-type unresectable or metastatic melanoma. With the combination, the ORR was 61% compared with 11% with ipilimumab alone. The ORR was independent of PD-L1 status.4

The combination was also associated with significantly higher rates of grade 3/4 adverse events, 54% with the doublet versus 24% with the monotherapy. An FDA decision is pending on a full approval for the combination in patients who are previously untreated, the application for which is based on the phase III CheckMate-067 trial.5

The PD-1/CTLA4 combination approach may be the right one in patients who need a rapid response, noted Luke, such as a younger patient who has brain metastases. However, in most patients, he is more comfortable using anti-PD-1 frontline monotherapy.

“The question becomes, can we find patients where we don’t have to expose them to the toxicity? We don’t know how to answer it yet,” said Luke, also mentioning how patient-specific treatment has become.

The toxicities with the combination are more frequent and more severe, added Gonzales.

Weber pointed out that the very steep and immediate response makes the combination “a perfect therapy for a BRAF wild-type patient who has aggressive, high LDH bulk, rapidly growing disease, or even a BRAF-mutated patient.”

Although the toxicities can be more intense, much of the reaction is biochemical, such as grade 3 hyperamylasemia with no symptoms, noted Weber. Grade 3/4 colitis or diarrhea can be very problematic, however.

Luke added that anyone who has toxicity that requires steroids should probably not receive more ipilimumab, but restarting anti-PD-1 therapy depends on the situation. The evidence suggests the responses last well past treatment.

“Most of the side effects happen very quickly…a lot of [patients] came off very early from treatment, and yet they’re ongoing in response far later,” Luke said. “So, I don’t think that we need to push all these doses.”

Jason J. Luke, MD

Jason J. Luke, MD

Switching Therapies

Weber pointed out that patients in the Check- Mate-064 trial who had toxicities with ipilimumab were able to continue with nivolumab. “I think you could have combination toxicity, much of which may well be the ipilimumab, stop, recover, and then go to the nivolumab maintenance,” Weber said.

Pembrolizumab and ipilimumab have indications that are independent of BRAF status. The approval of the nivolumab/ipilimumab combination is limited to BRAF wild-type disease. Weber pointed out that the evidence suggests “there is no difference in BRAF-mutated, BRAF wild-type patients in how well they respond to the combination.” A recent retrospective analysis by Larkin et al showed that nivolumab had similar efficacy and safety in both BRAF-mutant and BRAF wild-type disease. In addition, the efficacy and safety outcomes were similar regardless of prior BRAF inhibitor or ipilimumab treatment.9

Gonzales commented on the difficulty of knowing when to switch a patient from BRAF/MEK therapy to immunotherapy. “When I’ve started a BRAF/MEK combination on a patient and he’s had a great response, when do I switch him? Do I switch him to ipilimumab/PD-1 [inhibitor] combination…in the hopes of getting that durable remission?” Gonzales said.

Luke commented that he uses the BRAF/MEK inhibitor combination therapy as the backbone. “I know I can always go to it,” said Luke. “If patients come off of other things, we’re going to go back to it, get this back under control for a few months, and then we can think of what else can we try to do.”

Gonzales noted that the data with the combination of ipilimumab/nivolumab have prompted him to more often consider switching some patients to immunotherapy from the BRAF/MEK combination. “And I think my bar is falling as to when I do that because with BRAF/MEK combination, half the patients will die in about 2 years,” Gonzales said. “And so I’m not worried about the half that go beyond that, but it’s the front end of that curve that we might be able to impact better now rather than later.”

“I think in the context of some of this data that we’re getting now that a sizable fraction of patients do very, very well for a long time on targeted therapy,” Luke stated. “I think we need to push back on that message that everyone needs to get on [an anti PD-1 therapy]. There are other drugs that are very effective.”

References

1. Broderick J. FDA approves two new indications for pembrolizumab in advanced melanoma.OncLive.com. http://goo.gl/7yv1wV. Published December 18, 2015. Accessed January 2, 2016.
2. Inman S. FDA approves frontline nivolumab for advanced melanoma.OncLive.com. http://goo.gl/0XltAI. Published November 24, 2015. Accessed January 2, 2016.
3. Hodi FS, Gibney G, Sullivan R, et al. An open-label, randomized, phase 2 study of nivolumab (NIVO) given sequentially with ipilimumab (IPI) in patients with advanced melanoma (CheckMate 064). Presented at: 2015 European Cancer Congress; September 25-29, 2015; Vienna, Austria. Abstract 23LBA.
4. Postow MA, Chesney J, Pavlick AC, et al. Nivolumab and ipilimumab versus ipilimumab in untreated melanoma.N Eng J Med. 2015;372(21):2006-2017.
5. Bristol-Myers Squibb announces regulatory update for Opdivo (nivolumab) in advanced melanoma [press release]. Princeton, NJ: Bristol-Myers Squibb Company; November 27, 2015; http://goo.gl/z1LBnj. Accessed January 2, 2016.
6. Larkin JMG, Yan Y, McArthur GA, et al. Update of progression-free survival (PFS) and correlative biomarker analysis from coBRIM: phase III study of cobimetinib (cobi) plus vemurafenib (vem) in advanced BRAF-mutated melanoma.J Clin Oncol. 2015;33 (suppl; abstr 9006).
7. Robert C, Karaszewska B, Schachter J, et al. Two year estimate of overall survival in COMBI-v, a randomized, open-label, phase III study comparing the combination of dabrafenib (D) and trametinib (T) with vemurafenib (Vem) as first-line therapy in patients (pts) with unresectable or metastatic BRAF V600E/K mutation-positive cutaneous melanoma. Presented at: 2015 European Cancer Congress; September 25-29; Vienna, Austria. Abstract 3301.
8. Long GV, Stroyakovskiy D, Gogas H, et al. Dabrafenib and trametinib versus dabrafenib and placebo for Val600 BRAF-mutant melanoma: a multicentre, double-blind, phase 3 randomised controlled trial.Lancet. 2015;386(9992):444-451.
9. Larkin J, Lao CD, Urba WJ, et al. Efficacy and safety of nivolumab in patients with BRAF V600 mutant and BRAF wild-type advanced melanoma: a pooled analysis of 4 clinical trials.JAMA Oncol. 2015;1(4):433-440.