In an interview with the Journal of Clinical Pathways, Adam Kittai, MD, The Ohio State University Comprehensive Cancer Center, Columbus, OH, discussed his study on the causes of racial disparities in the overall survival among patients with chronic lymphocytic leukemia. His abstract “Analysis of Racial Disparities Accounting for Treatment Received in Chronic Lymphocytic Leukemia: A Real-World Cohort Analysis” was presented at the ASCO 2023 Annual Meeting.

Transcript:

Adam Kittai, MD: Hi, my name is Adam Kittai. I'm from The Ohio State University where I specialize in the treatment of chronic lymphocytic leukemia and Richter's transformation.

Can you give some background about your study and what prompted you to undertake it?

Dr Kittai: This study is a follow-up to a study that we published last year in Blood Advances. In that study we looked at the SEER database, which is a national database from 17 different registries across the country, and looked at racial disparities in CLL. What we found in that study was that Black patients had worse overall survival than White patients across the country, but what that study couldn't account for is what treatment our patients received. There had been some prior studies that showed that when patients are treated the same that they had similar outcomes. And so, ultimately, we wanted to do another study where were able to account for treatment received and potentially comorbidities.

Here, this particular study uses the Flatiron Health Database, which is a registry that captures data from academic and private centers around the country and also has what patients received in terms of their treatment, some comorbidity data in terms of their ECOG performance status, including race. And so, we used the Flatiron Health Database to answer some questions that we couldn't answer on our prior study.

Can you briefly describe how the study was conducted?

Dr Kittai: This study is sort of a population-based study or a retrospective analysis where the data was collected from the Flatiron Health Database that we just talked about. What we did was we looked at prognostic variables of survival and did a multivariable analysis to determine which prognostic variables were independently associated with survival using race and treatment received as variables.

What were the key findings of the study?

Dr Kittai: There were some interesting findings here. For one, we found that Black patients continued to have worse overall survival compared to White patients, and what we found specifically interesting here was that there was an interaction between race and age. When we see that in statistical design, what that means is that patients of different age didn't have the same effect across the board. And so, then when we dichotomized it between a younger age as in 30 to 50, middle age between 50 to 70 and greater than 70, we found that Black patients who were younger in that 30 to 50 range had a much worse overall survival than their White patients who are of the same age cohort. This disparity did decrease as patients got older where the older population had pretty much the same survival between White and Black patients.

Furthermore, one of the other interesting things that we found was that Black patients were more likely to be treated with small molecule inhibitors such as ibrutinib, acalabrutinib, zanubrutinib, and venetoclax. In addition, when patients were treated with the same type of therapy, so if they received our moderate therapy for CLL, they continued to do worse, meaning that being Black continued to be an independent prognostic variable for survival even when treatment was equivalent between Black and White patients. So, what this shows us is that the disparity between Black and White patients continues to occur, despite equal treatment.

To what do you attribute the worse overall survival seen in Black patients in your study?

Dr Kittai: That answer is kind of hard for us to say. I think that more work needs to be done to determine why this disparity exists. I think that it's probably multifactorial and it probably has to do with access to care. Over and over again, we're finding that access to care is an issue where Black patients have less access to primary care doctors and, ultimately, maybe less access to oncologists and hematologists as well. One of the signs that points to this is that the time from diagnosis to treatment is shorter with Black patients than White patients. Also, in other studies it has been shown that shorter time to first treatment is associated with worse prognostic survival. What that tells me is that our Black patients are arriving to the hematology clinic at a later stage, meaning that they have worse disease or are they coming with more aggressive disease, do they have worse prognostic variables in terms of their CLL? And so, these are all things that we need to look at, whether or not they're coming in with worse CLL, why they're coming with later stage disease. And I think, ultimately, it comes down to an access issue and access to health care.

Looking ahead, what potential impact do you hope your findings will have on decreasing disparities in outcomes among Black and White patients with CLL?

Dr Kittai: As I said in the last question, is that more work still needs to be done. I think that this just draws attention to the problem in terms of a checklist of what could be the problem, checks off issues as we go down. And so, here we're showing that despite treatment being equal Black patients continue to do worse. That means that maybe there's not a treatment issue here, meaning that as hematologists oncologists we are prescribing small molecule inhibitors equally to Black patients and White patients. I'm not saying that we should be sitting here tapping our backs and saying, "Wow, good job, we're great, we're making sure that everyone's treated the same." I think that we can say that we are doing that, which is great, but our patients are still having a worse survival, so that's not great.

In order for us to make a dent on that, we have to think outside of just what we can do as hematologists oncologists. What else can we do? Can we monitor these patients closer to make sure they have less adverse events? Can we make sure that each and every one of our patients has access to a primary care doctor? What else can we do as physicians to make an improvement in our patients' lives despite their race?

Is there anything else you would like to add?

Dr Kittai: The one thing I'd like to add here is that this is an ongoing project and one of the interesting things that we found here that we need to do more work on to figure out why and if it's impacting our results is, in our prior study we found that patients diagnosed after 2014 had improved survival than those patients diagnosed pre-2014. The reason why 2014 is key is that that was when ibrutinib got its first approval for CLL and revolutionized the way we treat CLL. Here we found that those patients diagnosed after 2014 had actually worse overall survival. I'm just highlighting this because there's always limitations to these population-based studies and more work needs to be done to figure out why these inconsistencies are there. And I'm excited to have this work done and hopefully present it at a future conference and a future manuscript and make sure that this is highlighted and that this continues to draw attention to this major issue.