When a B cell (either CLL or NHL) signals through the b cell receptor - a sequence of enzymes gets activated. This starts with Syk, goes to BTK, and then onto PI3 Kinase after several steps. S-Y-K stands for "spleen tyrosine kinase"
Back in 2005 as a fellow at Stanford, I figured it might be useful to shut off this pathway, so I proposed using a drug that was being developed for nasal allergies to treat NHL. The idea was a little far fetched at the time, so I had to prove my point in the lab before we could take it to the clinic. Didn't take long for me to realize I had no business trying to be a laboratory scientist although we did present the very first abstract on this idea back in 2007 at ASCO.
Our Syk inhibitor worked ok and was the first time we ever saw a "small molecule tyrosine kinase inhibitor" work against NHL/CLL. It was presented in the plenary session at ASH and eventually published in Blood here.
Richard Miller who was the chief medical officer at Pharmacyclics at the time but also saw patients with us at Stanford worked in the same clinic as me. He saw some of the patients responding to our drug (fostamatinib) and deduced that a compound he was working on called PCI-32765 that he got for free (best deal in pharma EVER) from Celera would work even better since it went after BTK. We took a casual gentleman's bet about which was the better target. I voted for Syk, he voted for BTK. Too bad because I could be retired by now had I picked BTK. PCI-32765 became ibrutinib. We treated the first CLL patients with it here in Eugene (I had left Stanford by then). The story is nicely told in a Forbes article (linked here).
Anyhow, I always believed the problem with going after Syk was not about the target, but about the drug we were using. So when the chance came up for us to try again with a new drug, I had to jump at the chance. Enter ENTOSPLETINIB.
After working on the phase I studies of idelalisib (back when it was CAL-101), we built some really nice relationships with Gilead. They are honestly a really nice group of folks. They picked up a drug (GS-9973) and we started testing it on patients with NHL and CLL. Like most of the drugs that inhibit BCR signaling, we got a really nice signal of efficacy and tolerability in CLL. Today, our first paper on the topic was published in Blood - link here.
Entospletinib looks to have pretty good efficacy in CLL. It is a twice daily pill. You really cannot compare across studies, but some of the early numbers look a lot like idelalisib. Lots of work left to be done and the trial is still recruiting patients with CLL (trial link here). Talk to your own doctor or seek an opinion at one of the centers offering the trial.
Thanks for reading.
Thursday, February 19, 2015
Tuesday, February 17, 2015
Frontline video
Some time ago, I wrote a blog post about dying (link here). It was an in depth reflection about the choices I see people make when confronting disease that has escaped control. While the post was well received and I got a lot of positive feedback, I recognize that I barely scratched the surface of a really important topic.
I would therefore like to continue to put up a variety of multimedia topics on the post that I think do a good job diving into a very difficult topic - because the topic is strangely taboo for many doctors and patients.
A while back, I added a podcast on hospice that I thought was especially good (link here)
Now Atul Gawande has put together a frontline video. Not sure if you ever watch frontline - but it doesn't pull any punches. Atul writes regularly for the New Yorker and really has a clear voice on many important topics. The video is getting very favorable reviews - so I wanted to post a link to it from the blog. Not necessarily a happy joyful topic, but a sober view to consider (link here).
In the meantime, we ARE making huge progress against CLL and NHL. I am more excited about research than ever before. I now find myself wondering if CLL or even follicular lymphoma might become curable cancers in the next ten years with emerging technologies. Please know that there is a lot of plausible hope out there - just putting these links out there to expose something that doesn't get the attention it deserves.
Thanks for reading (and listening and viewing).
I would therefore like to continue to put up a variety of multimedia topics on the post that I think do a good job diving into a very difficult topic - because the topic is strangely taboo for many doctors and patients.
A while back, I added a podcast on hospice that I thought was especially good (link here)
Now Atul Gawande has put together a frontline video. Not sure if you ever watch frontline - but it doesn't pull any punches. Atul writes regularly for the New Yorker and really has a clear voice on many important topics. The video is getting very favorable reviews - so I wanted to post a link to it from the blog. Not necessarily a happy joyful topic, but a sober view to consider (link here).
In the meantime, we ARE making huge progress against CLL and NHL. I am more excited about research than ever before. I now find myself wondering if CLL or even follicular lymphoma might become curable cancers in the next ten years with emerging technologies. Please know that there is a lot of plausible hope out there - just putting these links out there to expose something that doesn't get the attention it deserves.
Thanks for reading (and listening and viewing).
Monday, November 10, 2014
Rituximab monotherapy in CLL
I expect this blog post is going to ruffle some feathers. I can’t wait to see the responses in CLL forum, ACOR and elsewhere.
Patterns of care databases report that during the course of CLL approximately one third of patients will receive mono-therapy with rituximab (ie. rituximab with NO OTHER CHEMOTHERAPY). In fact, it is one of the most commonly utilized therapies in the management of CLL but should almost completely disappear in light of new clinical trial data. Based upon information published within the last 6 months, I think any treatment recommendation for single agent rituximab should he held to some additional scrutiny.
I will admit that I have given this therapy a limited number of times in CLL/SLL before under circumstances where I thought it might be appropriate. In CLL/SLL I think rituximab monotherapy is mostly outdated as of late 2014. Newer drugs such as obinutuzumab and Ibrutinib or new combinations such as idelalisib with rituximab have taken the place of rituximab monotherapy and I have changed my practice patterns as a result.
I recently blogged about rituximab monotherapy in follicular lymphoma and highlighted several key papers published that show how well this immunotherapy drug works. I also blogged about how the addition of lenalidomide may alter the landscape of front line treatment in follicular / indolent lymphoma. Indeed, rituximab monotherapy in indolent NHL (follicular, marginal zone) is a good treatment and definitely appropriate in many circumstances - particularly low tumor burden disease. But what is true for some indolent lymphoma isn’t necessarily true for ALL indolent b-cell disorders.
Small lymphocytic lymphoma and chronic lymphocytic leukemia are often considered two different manifestations of the same disease. Indeed, they are often referred together as CLL/SLL and lumped in with the rest of the indolent lymphomas. But different lymphomas have different behaviors and the response to rituximab is one key difference. Unfortunately, many doctors don’t pay too close attention to this distinction.
Rituximab is often a very easy drug to administer (some uncommon exceptions apply). In most indolent lymphomas and even CLL, you can see things get better and everyone seems happy. Both doctors and patients can be lulled into a sense that they are getting good therapy when they see things going the right direction – but good can sometimes be the enemy of better and may not be best in long term.
When rituximab first came out as a new drug it was noted that it had fairly modest activity in the management of chronic lymphocytic leukemia. Response rates were lower than in follicular lymphoma and didn’t last as long. Two key papers were published in the Journal of Clinical Oncology in 2001 authored by John Byrd (linked here) and Susan O’Brien (linked here). Both of them looked at ways to increase the dose of rituximab in order to get a better response in patients with relapsed disease. Dr. Byrd's paper looked at more frequent dosing and Dr O’Brien’s paper looked at giving mega-doses. Despite these efforts the overall response rates were between 35-45% and generally lasted 8-10 months.
Two key caveats though should dampen even that modest efficacy. The first is that this was in a population that had largely not been exposed to rituximab previously. Rituximab works better in patients who have never received it before. Nowadays virtually all patients get rituximab added to their first line therapy. When their disease relapses, a sizable population is getting rituximab mono-therapy and it is less likely to work when used a second time. The second caveat is that in 2001 we had different criteria for response assessments and CT scans were not used the same way they are today. Since lots of patients have enlarged lymph nodes hanging out in their chest or abdomen that cannot be detected by physical exam, looking more closely with CT scan would influence the determination of response and progression.
To get a good estimation of how well rituximab or even ofatumumab actually works, I would suggest looking at the control arm of the recently reported studies that led to the approval of idelalisib and Ibrutinib (linked here and here respectively). In these studies patients were randomly assigned to one of the “tried and true” or one of the new drugs but looked at rituxan exposed patients and used CT scans to determine progression. In the rituximab alone arm of the idelalisib study, the lymph node response rate was only 6% and the median progression free survival was under six months. Those response rates are really lousy. In the ofatumumab alone arm of the ibrutinib study, patients didn’t fare much better.
CLL researchers look at the patterns of care data and look at the utilization of rituximab monotherapy with a measure of disdain. While in the past I might have argued back that CLL patients treated in academic centers are fundamentally different from those seen in community practice (an assertion which has good data to support). Indeed, community patients are on average older, have more medical issues, and less good baseline organ function, and several other key differences compared to patients seen in academic medical centers. In the past, I think you could have used that logic to support some utilization of rituximab monotherapy but new data sets strip that away.
So what are the key new data sets?
In previously untreated CLL, obinutuzumab is better than rituximab. These are both CD20 antibodies but obinutuzumab has a number of key modifications that make it more effective than rituximab. In a paper published late last year (linked here), the German group performed a three arm study comparing chlorambucil to chlorambucil in combination with either rituximab OR obinutuzumab. From progression free survival perspective these came in at 11, 16, and 26 months respectively with obinutuzumab the clear winner. If you only compared the chlorambucil arm to the obinutuzumab arm, you even saw an overall survival benefit (second paper to ever show this in CLL). I have heard some people argue that the better performance of obinutuzumab was just based on differences in dosing in the study. I believe that is an argument made by people who are unfamiliar with obinutuzumab (gazyva). Clinically, it is a very different drug and the differences in dosing are pretty minimal.
This study was in CLL patients that are more typical for the disease (average age 71). Of course chlorambucil is somewhat of a pariah in the US and many have asked whether it is even a necessary part of the regimen. I was recently at the International Myeloma, Lymphoma, and Leukemia conference in NY where this topic was the subject of a one hour debate (hot Friday nights in the CLL research world). Hard to debate the topic given the lack of published data in this space but our group led a large study of obinutuzumab monotherapy that was presented at ASCO (link here) and will hopefully be published soon. My take on the data: you get a little more bang for the buck when you add the chlorambucil but not clear it is worth the cost, particularly with the agents available now in the relapsed setting.
Two years of average benefit in this disease can be meaningful. It will even be more meaningful if we can apply molecular data to pull out the patients less likely to benefit as well. There is new data from two studies that suggest the presence of NOTCH1 mutations makes CD20 antibody therapy considerably less effective (FC vs FCR and Chlorambucil vs chlorambucil-ofatumumab). Not sure if it applies yet to obinutuzumab yet, but hopefully that data will come out soon. You can test for NOTCH mutations here.
The second key data set (linked here) led to the approval of idelalisib. In this study, patients received either rituximab alone or in combination with idelalisib – a twice daily, non-chemotherapy pill. The difference was striking. Instead of a nodal response rate of 4% it was 96% and the difference in progression free survival was improved by 82%. In fact the difference was so striking the study had to be terminated for ethical reasons because the difference in overall survival started becoming too obvious to ignore (which we were not expecting to be different for technical reasons attributable to cross-over study design). This was the third study ever reported to show that there could be a survival difference in CLL with a new regimen.
I fundamentally believe that there is a significantly sized population of CLL patients who are not appropriate for an aggressive chemotherapy regimen. Let’s face it, the average age at first treatment in CLL is between 71-74 years old. Many are much older. Tack on heart and lung disease or multiple other medications, arthritis, etc which is entirely common in the population and things like FCR are absolutely prohibitive and even bendamustine-rituximab can be a stretch. If a CLL patient TODAY received the recommendation for rituximab therapy alone, I think it would be hard to justify why idelalisib isn’t included (note, I do not put rituximab or ofatumumab in combination with ibrutinib outside of a clinical trial as there is some suggestion that the ibrutinib may make the antibody work less well).
The third data set (linked here) compared Ibrutinib pills to ofatumumab infusions. Here too, the differences were so striking the study had to be terminated before it was planned to do so. In clinical research you set out to conduct studies when there is a sense of “equipoise.” That means there is an honest uncertainty about the difference between two therapies that you need to prove. The difference between ofatumumab and Ibrutinib in this particular study shatters the possibility of equipoise – the differences are too overwhelming. Response rates, progression free survival, and overall survival for patients treated with ibrutinib absolutely trounced ofatumumab.
So between these three papers the justification for rituximab monotherapy in either front line or relapsed CLL disappears. In front line, obinutuzumab is better than rituximab and in relapsed disease either adding idelalisib or swapping the two for Ibrutinib improve outcomes enough to fundamentally change the paradigm.
The remaining setting where CD20 antibody therapy such as rituximab or ofatumumab is used in CLL is as a “maintenance therapy” following some other chemotherapy. There have been several recent updates in this space and I think you could make a rational argument in support of maintenance though I’m not sure this is widely adopted in CLL treatment. I have provided a few links (here and here) but will leave this discussion for another time.
To summarize:
In previously untreated CLL, I think obinutuzumab has demonstrated sufficient clinical superiority over rituximab (either monotherapy or in combination with chlorambucil) to justify the swap in most cases - there is some debate about this point but I think the argument is settled. To date, there is not enough published data to routinely combine obinutuzumab with drugs like bendamustine or fludarabine outside of a clinical trial.
In patients with relapsed CLL, adding idelalisib to rituximab makes it work a whole lot better and Ibrutinib monotherapy trounces ofatumumab. Neither rituximab nor ofatumumab look nearly as good as single agents as we had believed in the past.
I anticipate the next several years of research will be about swapping out the various parts and putting them together again. Newer antibodies will be combined with newer pills and newer pills will be used earlier and earlier in the disease. It is a new era and we are quite fortunate to be in a time period where many of the “rules” are being re-written. Patients will live longer than our standard “prognosis” dictums and maybe we will even begin see a disease once considered incurable to be curable. Throw in BCL-2 inhibitors, CAR-T cells, bi-specific antibodies, and immune checkpoint inhibitors and I hope all patients will look to join in research studies so we can move the needle more quickly.
Thanks for reading
Patterns of care databases report that during the course of CLL approximately one third of patients will receive mono-therapy with rituximab (ie. rituximab with NO OTHER CHEMOTHERAPY). In fact, it is one of the most commonly utilized therapies in the management of CLL but should almost completely disappear in light of new clinical trial data. Based upon information published within the last 6 months, I think any treatment recommendation for single agent rituximab should he held to some additional scrutiny.
I will admit that I have given this therapy a limited number of times in CLL/SLL before under circumstances where I thought it might be appropriate. In CLL/SLL I think rituximab monotherapy is mostly outdated as of late 2014. Newer drugs such as obinutuzumab and Ibrutinib or new combinations such as idelalisib with rituximab have taken the place of rituximab monotherapy and I have changed my practice patterns as a result.
I recently blogged about rituximab monotherapy in follicular lymphoma and highlighted several key papers published that show how well this immunotherapy drug works. I also blogged about how the addition of lenalidomide may alter the landscape of front line treatment in follicular / indolent lymphoma. Indeed, rituximab monotherapy in indolent NHL (follicular, marginal zone) is a good treatment and definitely appropriate in many circumstances - particularly low tumor burden disease. But what is true for some indolent lymphoma isn’t necessarily true for ALL indolent b-cell disorders.
Small lymphocytic lymphoma and chronic lymphocytic leukemia are often considered two different manifestations of the same disease. Indeed, they are often referred together as CLL/SLL and lumped in with the rest of the indolent lymphomas. But different lymphomas have different behaviors and the response to rituximab is one key difference. Unfortunately, many doctors don’t pay too close attention to this distinction.
Rituximab is often a very easy drug to administer (some uncommon exceptions apply). In most indolent lymphomas and even CLL, you can see things get better and everyone seems happy. Both doctors and patients can be lulled into a sense that they are getting good therapy when they see things going the right direction – but good can sometimes be the enemy of better and may not be best in long term.
When rituximab first came out as a new drug it was noted that it had fairly modest activity in the management of chronic lymphocytic leukemia. Response rates were lower than in follicular lymphoma and didn’t last as long. Two key papers were published in the Journal of Clinical Oncology in 2001 authored by John Byrd (linked here) and Susan O’Brien (linked here). Both of them looked at ways to increase the dose of rituximab in order to get a better response in patients with relapsed disease. Dr. Byrd's paper looked at more frequent dosing and Dr O’Brien’s paper looked at giving mega-doses. Despite these efforts the overall response rates were between 35-45% and generally lasted 8-10 months.
Two key caveats though should dampen even that modest efficacy. The first is that this was in a population that had largely not been exposed to rituximab previously. Rituximab works better in patients who have never received it before. Nowadays virtually all patients get rituximab added to their first line therapy. When their disease relapses, a sizable population is getting rituximab mono-therapy and it is less likely to work when used a second time. The second caveat is that in 2001 we had different criteria for response assessments and CT scans were not used the same way they are today. Since lots of patients have enlarged lymph nodes hanging out in their chest or abdomen that cannot be detected by physical exam, looking more closely with CT scan would influence the determination of response and progression.
To get a good estimation of how well rituximab or even ofatumumab actually works, I would suggest looking at the control arm of the recently reported studies that led to the approval of idelalisib and Ibrutinib (linked here and here respectively). In these studies patients were randomly assigned to one of the “tried and true” or one of the new drugs but looked at rituxan exposed patients and used CT scans to determine progression. In the rituximab alone arm of the idelalisib study, the lymph node response rate was only 6% and the median progression free survival was under six months. Those response rates are really lousy. In the ofatumumab alone arm of the ibrutinib study, patients didn’t fare much better.
CLL researchers look at the patterns of care data and look at the utilization of rituximab monotherapy with a measure of disdain. While in the past I might have argued back that CLL patients treated in academic centers are fundamentally different from those seen in community practice (an assertion which has good data to support). Indeed, community patients are on average older, have more medical issues, and less good baseline organ function, and several other key differences compared to patients seen in academic medical centers. In the past, I think you could have used that logic to support some utilization of rituximab monotherapy but new data sets strip that away.
So what are the key new data sets?
In previously untreated CLL, obinutuzumab is better than rituximab. These are both CD20 antibodies but obinutuzumab has a number of key modifications that make it more effective than rituximab. In a paper published late last year (linked here), the German group performed a three arm study comparing chlorambucil to chlorambucil in combination with either rituximab OR obinutuzumab. From progression free survival perspective these came in at 11, 16, and 26 months respectively with obinutuzumab the clear winner. If you only compared the chlorambucil arm to the obinutuzumab arm, you even saw an overall survival benefit (second paper to ever show this in CLL). I have heard some people argue that the better performance of obinutuzumab was just based on differences in dosing in the study. I believe that is an argument made by people who are unfamiliar with obinutuzumab (gazyva). Clinically, it is a very different drug and the differences in dosing are pretty minimal.
This study was in CLL patients that are more typical for the disease (average age 71). Of course chlorambucil is somewhat of a pariah in the US and many have asked whether it is even a necessary part of the regimen. I was recently at the International Myeloma, Lymphoma, and Leukemia conference in NY where this topic was the subject of a one hour debate (hot Friday nights in the CLL research world). Hard to debate the topic given the lack of published data in this space but our group led a large study of obinutuzumab monotherapy that was presented at ASCO (link here) and will hopefully be published soon. My take on the data: you get a little more bang for the buck when you add the chlorambucil but not clear it is worth the cost, particularly with the agents available now in the relapsed setting.
Two years of average benefit in this disease can be meaningful. It will even be more meaningful if we can apply molecular data to pull out the patients less likely to benefit as well. There is new data from two studies that suggest the presence of NOTCH1 mutations makes CD20 antibody therapy considerably less effective (FC vs FCR and Chlorambucil vs chlorambucil-ofatumumab). Not sure if it applies yet to obinutuzumab yet, but hopefully that data will come out soon. You can test for NOTCH mutations here.
The second key data set (linked here) led to the approval of idelalisib. In this study, patients received either rituximab alone or in combination with idelalisib – a twice daily, non-chemotherapy pill. The difference was striking. Instead of a nodal response rate of 4% it was 96% and the difference in progression free survival was improved by 82%. In fact the difference was so striking the study had to be terminated for ethical reasons because the difference in overall survival started becoming too obvious to ignore (which we were not expecting to be different for technical reasons attributable to cross-over study design). This was the third study ever reported to show that there could be a survival difference in CLL with a new regimen.
I fundamentally believe that there is a significantly sized population of CLL patients who are not appropriate for an aggressive chemotherapy regimen. Let’s face it, the average age at first treatment in CLL is between 71-74 years old. Many are much older. Tack on heart and lung disease or multiple other medications, arthritis, etc which is entirely common in the population and things like FCR are absolutely prohibitive and even bendamustine-rituximab can be a stretch. If a CLL patient TODAY received the recommendation for rituximab therapy alone, I think it would be hard to justify why idelalisib isn’t included (note, I do not put rituximab or ofatumumab in combination with ibrutinib outside of a clinical trial as there is some suggestion that the ibrutinib may make the antibody work less well).
The third data set (linked here) compared Ibrutinib pills to ofatumumab infusions. Here too, the differences were so striking the study had to be terminated before it was planned to do so. In clinical research you set out to conduct studies when there is a sense of “equipoise.” That means there is an honest uncertainty about the difference between two therapies that you need to prove. The difference between ofatumumab and Ibrutinib in this particular study shatters the possibility of equipoise – the differences are too overwhelming. Response rates, progression free survival, and overall survival for patients treated with ibrutinib absolutely trounced ofatumumab.
So between these three papers the justification for rituximab monotherapy in either front line or relapsed CLL disappears. In front line, obinutuzumab is better than rituximab and in relapsed disease either adding idelalisib or swapping the two for Ibrutinib improve outcomes enough to fundamentally change the paradigm.
The remaining setting where CD20 antibody therapy such as rituximab or ofatumumab is used in CLL is as a “maintenance therapy” following some other chemotherapy. There have been several recent updates in this space and I think you could make a rational argument in support of maintenance though I’m not sure this is widely adopted in CLL treatment. I have provided a few links (here and here) but will leave this discussion for another time.
To summarize:
In previously untreated CLL, I think obinutuzumab has demonstrated sufficient clinical superiority over rituximab (either monotherapy or in combination with chlorambucil) to justify the swap in most cases - there is some debate about this point but I think the argument is settled. To date, there is not enough published data to routinely combine obinutuzumab with drugs like bendamustine or fludarabine outside of a clinical trial.
In patients with relapsed CLL, adding idelalisib to rituximab makes it work a whole lot better and Ibrutinib monotherapy trounces ofatumumab. Neither rituximab nor ofatumumab look nearly as good as single agents as we had believed in the past.
I anticipate the next several years of research will be about swapping out the various parts and putting them together again. Newer antibodies will be combined with newer pills and newer pills will be used earlier and earlier in the disease. It is a new era and we are quite fortunate to be in a time period where many of the “rules” are being re-written. Patients will live longer than our standard “prognosis” dictums and maybe we will even begin see a disease once considered incurable to be curable. Throw in BCL-2 inhibitors, CAR-T cells, bi-specific antibodies, and immune checkpoint inhibitors and I hope all patients will look to join in research studies so we can move the needle more quickly.
Thanks for reading
Subscribe to:
Posts (Atom)