What's In Store for Hematologic Malignancies?
Andrew D. Zelenetz, M.D., Ph.D. weighs in on recent research and the future of treating hematologic malignancies.
BY Gina Columbus and Ellie Leick
PUBLISHED January 04, 2017
Research is needed in the first-line treatment of hematologic malignancies, according to Andrew D. Zelenetz, M.D., Ph.D.
For patients with indolent lymphoma or chronic lymphocytic leukemia (CLL), the optimal frontline choice does not exactly exist, he says. While treatment options have evolved and improved over time, researchers are still debating between bendamustine- or CHOP-based regimens for follicular lymphoma, for example. And while chemoimmunotherapy remains a standard frontline approach for younger, fit patients with CLL, it’s not as clear as to what is best for the older patient population.
Zelenetz, the medical director of Quality Informatics at Memorial Sloan Kettering Cancer Center, spoke on indolent lymphoma and CLL treatment in an interview with CURE.
Can you provide an overview of the current landscape of indolent lymphoma?
When you are diagnosed with follicular lymphoma, your expected survival is inferior to the age match general population, but not by very much. The median survivals in this disease have changed from eight to 10 years 25 years ago, to 16 to 20 years as a median survival today.
We know that first-line therapy is important. First-line therapy can result in long progression-free survival (PFS). We’re still struggling to find the optimal first-line therapy, whether it’s bendamustine-based, or CHOP or CVP; the answer is not crystal clear.
One of the interesting things we saw from the 2016 ASH Annual Meeting is what’s called the GALLIUM trial, which is bendamustine plus CHOP or CVP combined with Rituxan (rituximab) or Gazyva (obinutuzumab). This was a head-to-head comparison of Rituxan versus Gazyva in indolent lymphoma. The follicular lymphoma cohort was spoken about at the presentation, while the non-follicular indolent cohort wasn’t. It actually met its endpoint. The statistical plan was looking for an improvement (with Gazyva)—a hazard ratio of 0.74. The hazard ratio is 0.66. That corresponds to a 50 percent increase in the PFS.
People think that not much has been accomplished because the curves don’t look that different, but the curves can’t look that different. A 50 percent increase in PFS is going to correlate to about a 10-year survival after first-line therapy. That’s pretty impressive, and it’s going to be hard to beat. We have a large, randomized study comparing Rituxan and Revlimid (lenalidomide) with Rituxan chemotherapy, but it’s going to be hard to beat a median PFS of 10 years with chemoimmunotherapy.
What about the CLL landscape?
In the CLL world, we are still struggling with first-line therapy. There’s a group of patients, particularly young, fit patients with mutated immunoglobulin genes, who have a 10-year PFS in the range of 70 percent. They’re probably cured. There are very few events in that group of patients. From that group, which is a very small group, we can define a standard of care, which is FCR (fludarabine, cyclophosphamide, and Rituxan).
However, for the older patient or the fit patient who does not have a mutated immunoglobulin gene, chemoimmunotherapy works, but will fail. Findings from the RESONATE-2 trial suggest that you can give Imbruvica (ibrutinib). However, the problem with Imbruvica is it’s going to be far too expensive in the United States, let alone the rest of the world. This is the economic challenge of introducing new drugs early in the treatment paradigm. We know Imbruvica works really well after chemoimmunotherapy. In the selected patient, Imbruvica should be used. We now have Zydelig (idelalisib) and Venclexta (venetoclax), so we have other options in the relapsed refractory setting.
There are a couple of the emerging things from the 2016 ASH Annual Meeting in the relapse setting for indolent lymphoma. Imbruvica looks okay in marginal zone lymphoma, but positively awful in follicular lymphoma. Again, this is pointing out that all indolent lymphomas are not created equal; these are different diseases.
In upfront CLL, following chemoimmunotherapy, there seems to be a role for Revlimid maintenance. Here’s yet another treatment we have that can [improve] PFS — not in itself a very cheap one either — but at least this was demonstrated in a particularly high-risk population that did not achieve an minimal residual disease (MRD)-negative status. These are patients who had greater than 10-2 residual disease or between 10-2 and 10-4 but another adverse feature, such as an unmutated immunoglobulin gene, p53mutation, or deletion 17p. This group of patients, when selected, had a clear benefit in PFS. It is too early to see any survival difference, and there may not be an overall survival (OS) difference given the ability to treat patients in the relapsed setting.
Going back to indolent lymphoma, you mentioned there is no optimal first-line choice. What are the factors to consider when looking at a patient to determine which therapy you are going to give them first?
It’s interesting because the GALLIUM study is actually the first large-scale, well-done study of a bendamustine-containing treatment. People may argue we already have the StiL trial and the BRIGHT trial, but the StiL trial was a community-based study. The toxicity was dramatically underreported, as well as the long-term consequences because the follow-up wasn’t very good.
The BRIGHT study was an overall response rate study, so follow-up essentially ended at response. One of the things we’ve seen in the GALLIUM study is there is an excess early-death rate in bendamustine-treated patients. When I first saw that data number months ago, I was concerned. That will have a bearing on what I do in the upfront setting. I will probably give a little more old-fashioned CVP and stick to CHOP-based treatments. Based on the data, integration of Gazyva in chemoimmunotherapy and follicular lymphoma really is the right way to go.
Given the data we saw at this year's ASH Annual Meeting, where do you see the future for indolent lymphomas going?
The challenge is going to be in identifying high-risk patients. If the median time to progression is going to be around 10 years, what we really need to do is identify those 20 percent or so patients who fail within the first 12 months or the first 24 months. Those patients have a very poor survival, but the challenge has been to identify them when we first treat them. Those are the patients who need to be targeted for novel treatment strategies because chemoimmunotherapy is a very effective treatment for the standard-risk patient.
In CLL, what is your go-to approach for when patients fail on either Imbruvica or idelalisib?
There are two ways to fail a kinase inhibitor. One is to progress. If you progress on Imbruvica, then going to the other kinase inhibitor apparently doesn’t work very well. We know that from a retrospective study presented at the 2015 ASH Annual Meeting by Anthony Mato, M.D.
Secondly, you can fail if you’re intolerant of the drug. You come off of Imbruvica because you have severe muscle cramping and you just can’t tolerate any more. You have copious diarrhea on idelalisib but you’re responding, then switching to the alternative kinase inhibitor is a viable treatment strategy.
However, for patients who are progressing on Imbruvica and idelalisib, we saw preliminary data from Jeffrey Jones, MD demonstrating that single-agent venetoclax is very effective in this group of patients with very high response rates. A number of patients were actually able to achieve an MRD state. We do have treatment options for patients who are progressing on the kinase inhibitors.
What are your thoughts on acalabrutinib?
Acalabrutinib and BGB-3111 are pseudo next-generation [drugs]. The reason they are pseudo-next generation is they’re really not “next-generation” drugs. They have exactly the same mechanisms of action. They bind to the active site cysteine and they covalently modify the drug.
We know that acalabrutinib and BGB-3111 don’t interfere with antibody-dependent cell-mediated cytotoxicity in culture, so they should play better in vivo with monoclonal antibodies. That has to be proven. There should be fewer T-cell effects with acalabrutinib and BGB-3111. We know they can achieve very high levels of occupancy of BTK and are highly active in CLL.
If you had the two drugs at the same time in the laboratory and had to pick one, you might have picked one of the others, but once Imbruvica is there it becomes pretty hard to displace—unless there’s a clear differentiating factor. That might be in combination with drugs. Limited duration of therapy in combination might be more effective with one or the other of the BTK inhibitors.
What are your thoughts on the ongoing research exploring Opdivo (nivolumab) in CLL?
There was a trial of Opdivo combined with Imbruvica with Richter’s transformation. All of the activity observed with Opdivo was in patients who had Richter’s transformation, which is the activity you would expect Imbruvica to have in patients with CLL. Opdivo really added something to patients with Richter’s transformation, but not very much to patients with CLL.