GRACE :: Lung Cancer

EGFR mutations and other molecular markers

Mutations, FISH, immunohistochemistry, and other emerging molecular markers predicting clinical benefit with EGFR-based therapy.

Dr West

Is immunotherapy the wrong choice for some lung cancer patients?

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Amidst all of the glowing reports about immunotherapy for lung and many other cancers, it would be understandable for patients and physicians to be tempted to rush toward prioritizing immunotherapy as the first treatment strategy to pursue. In fact, a highly publicized trial called KEYNOTE-024 was just presented at the ESMO meeting in Copenhagen and demonstrated a significant improvement in progression-free and overall survival over standard chemotherapy doublet treatment as the first line approach for patients with high level expression of the PD-L1 protein on their tumor (about 30% of patients).  But there is also converging evidence that some patients are consistently less likely to benefit from immunotherapy — specifically, those patients with an EGFR mutation and perhaps others with another “driver mutation” such as an ALK or ROS1 rearrangement.  This is an important issue to know, because I and some other lung cancer specialist colleagues see patients with one of these highly targetable lesions sometimes being mistakenly recommended immunotherapy over the optimal targeted therapy for their cancer, or patients deflect a recommendation for an EGFR or ALK inhibitor in favor of immunotherapy based largely or completely on the hype around the latest new idea in cancer treatment.

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Dr West

Divergent Paths for Tagrisso (Osimertinib) and Rociletinib for EGFR T790M Mutation-Positive NSCLC and Acquired Resistance: What Happened, and Where Are We Now?

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For patients with an activating EGFR mutation and who develop “acquired resistance”, the pattern of progression that occurs after a sometimes long period of good initial response to an oral EGFR tyrosine kinase inhibitor (TKI) like Tarceva (erlotinib), Iressa (gefitinib), or Gilotrif (afatanib), the evolving story of the treatment options has been a wild ride with several ups and a few downs. Over the last two years, several “third generation EGFR TKIs” with a strong affinity for EGFR activating mutations and, importantly, a different mutation called T790M, which is seen in 50-60% of patients with EGFR mutation-positive acquired resistance, but very low affinity for “wild type” (normal, non-mutated) EGFR molecules (which mediate the common, problematic side effects with EGFR TKIs, such as rash and diarrhea).  Given the very different paths that the two leading entrants – Astrazeneca’s Tagrisso (osimertinib, also previously known as AZD9291 and transiently as merelitinib) and Clovis’s rociletinib (also known as CO-1686) – it’s high time to review what has happened to get to where we are now.

The annual ASCO meeting in 2014 included very prominent presentations about these agents (Tagrisso and rociletinib, respectively), at that point still in early trials with several dozen patients each, that showed both agents had marked activity against the subset of patients with acquired resistance whose tumors test positive for T790M. At that time, AZD9291, which ultimately became osimertinib and then branded as Tagrisso, was a half-step ahead in terms of a slightly larger number of patients tested, but both agents were very promising for a population in which alternative treatment options other than standard chemotherapy. Though some concerns were raised about hyperglycemia (high blood sugar levels) in patients on CO-1686, my view at the time was that in people facing the threat of an advanced cancer, taking pills or even possibly insulin to manage blood sugar levels wasn’t likely to be a major issue if it worked effectively. Like many other lung cancer specialists and general oncologists alike, my perspective was that access to either agent would be a welcome opportunity for patients eligible for an accessible clinical trial. 

These two agents have been widely studied in a range of global trials as they continued their footrace over the next 12-18 months. In August, 2015, the remarkably early results with these two agents was featured in back to back articles (on Tagrisso and rociletinib, respectively in the prestigious New England Journal of Medicine.

But since that time, the paths of those two agents have diverged remarkably.  Tagrisso became FDA-approved in November, 2015 after continuing to demonstrate a response rate of significant tumor shrinkage in about 55-60% of T790M-positive recipients and up to 90% experiencing “disease control” that includes less significant shrinkage and stable disease. Importantly, these responses tend to last for many months to a year or longer, and this longitudinal treatment has been associated with a very low risk of significant side effects, with most patients experiencing either no issues or a rash and diarrhea that is so minimal that, in my experience, they haven’t felt warrants a hint of complaint.  The value of offering Tagrisso for T790M-positive acquired resistance has really changed the standard of care for EGFR mutation-positive patients with progression, making it instantly critical to seek and hope to find a T790M mutation, with a valuable subsequent treatment option to pursue before moving on to other options routinely offered for advanced NSCLC.

The path of rociletinib has been very dramatic over the past 6-7 months, but unfortunately it has been in a downward trajectory. Though provocative work over the past year has shown that this agent could work well in patients with T790M detected even in plasma, perhaps obviating the need for repeat tissue biopsies, the side effect profile with further use made it arguably a less attractive option than Tagrisso.  In my own experience, the constellation of nausea, diminished appetite, and diarrhea could create a cascade of weakness and misery that required aggressive dose reductions in a significant minority of patients and an occasional patient expressing dramatically “if this is what I need to do to have my cancer respond, I’d rather die” (though other patients certainly tolerate it better). But the biggest hit came in November, 2015, when the FDA reported that it was planning to delay a decision on potential approval of rociletinib after updated information revealed that the response rate reported to rociletinib of 59% was actually an “unconfirmed” response rate that dropped to about half that rate when looking only at confirmed responses (though the latest published update pegs response rate at 45%). The fortunes for rociletinib, along with Clovis’s stock price, dropped like a rock.

Tailspin

 Since then, clinical trials with rociletinib have continued on, and the FDA has continued its review process for the drug. The Oncology Drug Advisory Committee (ODAC) to the FDA, eviewing the evidence in April, came back with a 12-1 vote against approval until results from a randomized trial of rociletinib vs. chemotherapy be completed and demonstrate a clear benefit for rociletinib.  Then, in early May, Clovis announced very suddenly that the FDA, which almost always followed ODAC’s thoughtful recommendations, had notified the company that the FDA would not be offering an approval until further data supported its use. In that same press release, Clovis announced that it was terminating all trials with rociletinib (and was laying off 35% of its employees).

One important issue that the potential approval of rociletinib raised was the question of whether it should be compared to osimertinib or not. Technically, rociletinib didn’t need to be better than its predecessor to the market in the same space, but it is hard to determine what value there is in offering an agent with seemingly less activity and worse side effects than an agent we already have available. This issue of a strong incumbent will be a critical factor for other would-be challengers, further behind in development, which enter a world with Tagrisso as an entrenched, effective therapy in this setting, so how might other agents fit in?

A key relevant question here is how similar or dissimilar these agents truly are. One might well assume that there is a great deal of “cross-resistance” to drugs in the same family, as we see minimal activity of one first or second generation EGFR TKI after another (such as trying Tarceva after Iressa, or Gilotrif after Tarceva), just as you wouldn’t expect to have many people wildly excited about having a Pepsi after drinking a two liter bottle of Coke. But in fact, Dr. Lecia Sequist and colleagues from Massachusetts General Hospital recently reported that they have seen several cases of tumor shrinkage or prolonged stable disease on Tagrisso – including in the brain as well as other parts of the body — in patients who had demonstrated clear progression on rociletinib previously. As someone who had patients progressing on rociletinib in clinical trials, I followed this lead and have treated several of my patients with Tagrisso and also seen several very encouraging responses after progression on rociletinib. This is an important finding for patients in this setting who may benefit.

These advances are very significant, but we must still acknowledge the work that still needs to be done. Third generation EGFR TKIs may prove to offer meaningful benefits to the 40-50% of patients with T790M-negative acquired resistance, or we may need to search for better options elsewhere. It will also represent a great breakthrough if we can do repeat biopsies to check for T790M or other mutations in circulating plasma of patients rather than be required to pursue invasive biopsies at several time points over the course of treatment.  Though we probably can’t predict future developments much better than we might have predicted the drama in this space over the past two years, I can predict that it will be eventful and that we will only have a better understanding of and treatments for EGFR mutation-positive NSCLC in the future.

What do you think of these developments?


GRACE Video

Rociletinib/Osimertinib for EGFR T790M-negative NSCLC

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GRACE Cancer Video Library - Lung

GCVL_LU-F13_Rociletinib_Osimertinib_EGFR_T790M-Negative_NSCLC

 

Dr. Jack West, Swedish Cancer Institute, reviews trial evidence for the efficacy of rociletinib and osimertinib for EGFR acquired resistance not driven by a T790M mutation.

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For patients who have an activating mutation in their cancer known as EGFR we have several very good first line treatment options to consider. There are three leading contenders as oral targeted therapies that block EGFR and tend to work very well for patients with an EGFR mutation. These agents are known as Iressa (gefitinib), Tarceva (erlotinib), and Gilotrif (afatinib). These agents have a chance of shrinking the tumor in the range of 60% to 75% which is great, but unfortunately these responses do not last forever and on average, patients will develop progression of their cancer, so-called acquired resistance to this first line therapy, after something in the range of nine to 12 months — can be less, can be more.

The question is what to do when that occurs. Well, there are a couple of agents that have shown great promise and great activity, at least in the subset of patients who have a mutation, found at the time of this acquired resistance, that is known as T790M. And so we repeat a biopsy of an area of progressing cancer while patients are on and progressing on this first line EGFR inhibitor, and 50% or 60% will have this acquired resistance mutation known as T790M. For those patients, we standardly consider drugs like osimertinib and rociletinib, and I say standardly consider as if they’re commercially available, and they’re not yet, at this moment in late 2015, FDA approved but it is expected that both will be approved by the FDA based on their very good activity in the very near future, perhaps by the time you see this.

But these agents are best studied and have their greatest activity in the patients with a T790M mutation. So what about the patients who are still 40% or 50% of that population with progressing cancer on an EGFR inhibitor who don’t have a T790M mutation? It turns out that both of these agents have good activity, or at least some degree of activity, in patients who are T790M-negative. It doesn’t tend to be as long-lasting and the response rates tend to be lower, but the activity is certainly encouraging.

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When you look at what’s called a waterfall plot that’s shown here of how patients respond, the bars going downward represent patients whose cancers have shrunk, and the ones that go upward are the ones whose cancers have progressed on a therapy. You can see that when we look at patients who received osimertinib, the AstraZeneca drug AZD9291, there is good activity in the majority of patients who receive this agent, even if they have no T790M mutation.

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The same is true for rociletinib, the Clovis drug CO1686 — the waterfall plot shows that most of the bars do go down, and that a lot of patients receive a substantial benefit, even if they do not have T790M detected in their rebiopsied tumor.

So there are studies that are looking specifically at these agents in patients who are T790M-negative. A trial with rociletinib known as TIGER-3 is looking at patients who have received prior EGFR inhibitors like Iressa, Tarceva or Gilotrif, and have also received prior chemotherapy. These patients are then randomized to either receive rociletinib or a standard chemotherapy as a single agent, and there are several that your doctor can choose from. This trial will be looking at which patients do better depending on whether they get the targeted therapy or standard chemotherapy.

There is another trial being done with osimertinib in combination with an EGFR monoclonal antibody known as necitumumab, so a two drug combination being looked at in patients who are T790M-negative after progressing on a first line EGFR inhibitor. So both of these agents are being studied not just in patients with a T790M-positive cancer, but a T790M-negative cancer, and if you do have acquired resistance and are found to not have a T790M mutation, you might want to look into information about these trials to see if one might be a good choice for you.


GRACE Video

Local Therapy for Limited Acquired Resistance

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GRACE Cancer Video Library - Lung

GCVL_LU-FB06_Local_Therapy_Limited_Acquired_Resistance

 

Dr. Jared Weiss, UNC Lineberger Comprehensive Cancer Center, describes the types of situations in which local therapy is appropriate for treating limited acquired resistance.

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It’s my privilege to speak to you today about a favorite topic of mine, local therapy for limited acquired resistance.

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So just five years ago, we were celebrating the curves that I’m showing you here. This is great — we have a targeted therapy, it works better than chemotherapy, it’s less toxic, it’s more convenient, demedicalizes the patient’s life, and this is a legitimate victory and I don’t want to take that celebration away, but I think only five years later, I guess now six years later, I think the perspective is a little bit different as our drugs get more effective and the bar goes up.

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We say these drugs are lasting less than a year on average — now what? We’re trying to find something other than chemotherapy. There are multiple promising approaches, including next generation drugs aimed at the targeted therapy, but I’m going to talk to you today about a slightly different approach. Before doing so, I want to just share that this story is very analogous for crizotinib and ALK and ROS1, it’s the exact same story.

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The approach I colloquially call “weeding the garden.”  This approach is what it sounds like — using some kind of local ablation or surgery to take out areas of progression, areas that are growing despite the targeted therapy, the areas that perhaps have a resistance mutation of some kind, and then using the original therapy for the rest of the cancer that’s still well controlled.

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So when might this make sense, and when might it not? Well the situation  where it surely does not make sense is classical progression. Prior to the advent of targeted therapies and immunotherapies, there was really only one pattern of progression that we mostly saw: when the cancer was going to grow, it grew everywhere and it grew in multiple new spots — not a time when weeding the garden makes good common sense.

We have two new patterns of progression where it does make more common sense. One is oligoprogression — that is what it sounds like, you have progression in just one or two spots, those spots maybe have T790m or some other resistance change, where the rest of the cancer is beautifully controlled still on the targeted therapy. The other situation is when the progression is in an area that the drug doesn’t get to so well. So there’s this filter between the rest of the body and the brain called the blood-brain barrier. Its job is to keep poisons out of the brain and it appropriately sees most of our anti-cancer therapies as poisons and keeps them out of the brain. You can have cancer growing in the brain not because there’s some resistance gene, some secondary mutation or amplification of some gene, but just because the drugs aren’t getting there well. I think that’s another area where it conceptually makes sense to consider weeding the garden.

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For EGFR, I think radiation is a particularly promising approach to do this — at left you can see data preclinically in the lab on why EGFR mutated cells seem to be more sensitive to radiation than non-mutated cells, and at right some human data to back up that this actually happens in real people.

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This approach has been tried retrospectively — the Memorial group here did a mostly surgical series where they got a median time until progression of another ten months after this approach, so they’ve mostly cut out the sites of progression and started TKI back up again.

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Our colleagues at Colorado, where we happen to be taping today, have done this in a mixed series of EGFR and ALK patients; they show their data separately for whether the progression was primarily in the brain or elsewhere. When the brain was the primary site of progression, they got another 7.1 months out of targeted therapy. When it was outside of the brain, they got an additional four months.

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I have the privilege to lead a study prospectively evaluating this approach for patients with oligoprogression on EGFR mutation. The design is very simple, you have to have gotten benefit out of an EGFR TKI, typically erlotinib in the first line in this country, but no prohibition against gefitinib or afatinib, but now one or two sites, up to five sites, are growing. We do stereotactic radiosurgery to those sites of progression, and then restart a TKI for the remainder of the sensitive disease. My collaborators are shown at right, including many GRACE contributors.

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[In 2015] Pfizer agreed to fund a very similar study for patients who have previously received a benefit on crizotinib but are now  progressing. The design is rather similar here, where we do radiosurgery to the sites of progression, restart the crizotinib, and because which mutations are sensitive to crizotinib is evolving at the current time, we don’t define this on a molecular basis but on a practical basis — patients who have received benefit but now have growth in four or less spots.

You might reasonably ask me the question, “well we have all these exciting next generation tyrosine kinase inhibitors we’ve heard about on GRACE, we have the clovis compound and the AZ compound for EGFR, we have alectinib and ceritinib for ALK — why not just jump to one of those?” I actually think that would be a perfectly reasonable approach, perhaps the preferred approach when there’s poly progression, but I can show you graphically why you might consider the approach that I’m talking about.

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So here’s the approach of starting with the first-gen TKI and moving straight to the next-gen TKI. Let’s imagine that my approach of eliminating oligoprogressive disease only has minimal efficacy, only gets you a few extra months on the first line therapy, you might look at this graphically this way: that you’ve inserted an additional therapy, you’ve squeezed a little more juice from the orange, in first line, before moving to that next line. But it’s entirely possible that in reality we get something better than that. So the first of these alternative hypotheses is that we get a longer duration of control — perhaps ten months or a year, replicating the original experience with the first line targeted therapy. Here we have a larger advantage to total cancer control before moving on to chemotherapy. Alternatively, if we’re radiating spots, we may be eliminating some of the spots that are eventually going to cause resistance on second line TKI, and so it’s entirely possible, I would call it my professional fantasy, that we’ll actually not only prolong the duration of benefit of the first line drug, but make the second line drug last longer when we get there. The possibility of that approach is shown at the very bottom — that fantasy phenomenon.

So I thank you for your kind attention.


GRACE Video

Combinations and Other Options for Acquired Resistance in EGFR Mutation-Positive NSCLC

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GRACE Cancer Video Library - Lung

GCVL_LU-F14_Combinations_Other_Options_EGFR_Acquired_Resistance

 

Dr. Nathan Pennell, Cleveland Clinic, describes other options for treatment of acquired resistance, including chemotherapy, ablation with SBRT and a combination of Gilotrif and Erbitux.

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On other videos in this series, we talked about next generation inhibitors for molecularly defined subgroups of patients who’ve developed acquired resistance. Now I want to talk about other options — if you don’t have a clinical trial available, or if you’ve already tried a next generation inhibitor and it stopped working.

We know that for patients with EGFR mutation-positive lung cancer, or ALK-positive lung cancer, the targeted therapies with drugs like Tarceva or Xalkori are more effective than chemotherapy and are really the standard of care for these patients. But unfortunately, most patients go on to develop what’s known as acquired resistance, where the cancer eventually begins to grow despite initially being controlled by the targeted therapy. While there are drugs being developed that are better inhibitors in that setting, they’re not always available outside of a clinical trial, or perhaps not ideally suited for a particular patient’s situation. So, what do you do in that setting?

There are a number of different options. The first thing to keep in mind is, not every patient who is developing acquired resistance needs to change what they’re doing. Sometimes, if the cancer is beginning to grow, it can grow in a very slow, asymptomatic way. In other words, it’s not causing symptoms, every time you do a scan it’s a little bit bigger, but the patient feels fine, is not having a lot of side effects from the drugs — you can continue to watch these. This can be anxiety-provoking, but I’ve watched patients for six months, nine months, sometimes longer before we really need to make a change. In the same vein, we know that about 20% of patients who develop acquired resistance don’t develop resistance everywhere in the body. Maybe only one or a couple of the tumors are growing, and if you biopsy those you can see that new mutations and mechanisms of resistance can arise in individual tumors while the rest of the cancer remains under control.

To borrow a phrase from my friend Dr. Ross Camidge at the University of Colorado: don’t overthink it — if one of the tumors is growing and all of the rest of them are the same, we can ablate the tumor that’s growing, essentially eliminate that, and patients can stay on the drug that they’re already on, sometimes, again, for six or nine months, sometimes longer, before resistance emerges elsewhere in the body.

The most commonly used mechanism for this is something called stereotactic body radiotherapy, or SBRT, which is a very effective way of using radiation to target individual tumors that tends to have very few side effects. Most patients, however, will eventually need to change the therapy that they’re on.

So, if you can’t stay on the drug any longer and you need to make a switch, one thing that many patients don’t even consider is going to chemotherapy. We know now that, since patients are being tested for EGFR mutations and ALK gene fusions upfront, many of them never receive chemotherapy and they start on a targeted therapy, but chemotherapy can be very effective for patients with EGFR mutant lung cancer or ALK-positive lung cancer, and in fact, tends to work better on average than in people who don’t have these mutations. I’ve had many patients who’ve had longer periods of disease control on chemotherapy than they had on the targeted therapies that everyone was so excited about. So, don’t despair if your doctor suggests chemotherapy because it may be a good option for you.

There are other clinical trials available, we’ve got the immune therapies that are out there — just the same treatments that are available for other types of lung cancer. There is one other thing I want to mention, for EGFR mutation-positive patients, there is a second generation inhibitor called afatinib, or Gilotrif. Gilotrif by itself is not effective for acquired resistance in EGFR, but when you add it to a second EGFR inhibitor called Erbitux, or cetuximab, in a large phase IB trial, we know that about a third of patients will have a major response to that combination, regardless of why their cancer developed acquired resistance. Sometimes this can last, on average, seven or eight months; I’ve used this and actually seen pretty good responses. It can be a little bit tough — both drugs cause diarrhea and skin rash, which can be worse when given together, but these tend to be manageable for most people.

So, in 2015, if your cancer develops acquired resistance to a targeted therapy and there isn’t a clinical trial available for one of the newer agents, don’t despair. There still are a number of things that can be tried, from remaining on the drug, to ablating the limited number of spots that are progressing, to switching to chemotherapy or participating in another clinical trial.


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