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Real-World Treatment Patterns, FLT3 Testing, and Outcomes in AML

January 14, 2021

 

Amer Zeidan, MBBS, MHS, Yale University School of Medicine and Yale Cancer Center, New Haven, Connecticut, discusses updated results from an ongoing retrospective study examining FLT3 testing trends, treatment patterns, and overall survival in patients with relapsed/refractory FLT3-positive acute myeloid leukemia (AML).

Dr Zeidan presented these results at the virtual 62nd American Society of Hematology (ASH) Annual Meeting.

Transcript

Hello. My name is Amer Zeidan and I'm Associate Professor of Medicine at Yale University, in section of hematology, and the director of Hematology Early Therapeutics research.

It's my pleasure to be talking about the streamlined study today, about acute myeloid leukemia and the FLT3 mutation. FLT3 mutation is one of the most common mutations that are seen within acute myeloid leukemia patients. Up to 30% of patients have this abnormality detected.

There have been several drugs that have been approved. Midostaurin in the frontline setting, in combination with intensive chemotherapy, as well as the use of gilteritinib in relapsed/refractory patients.

It's important to understand the trends in FLT3 testing and utilization across the US in real‑life settings. Here we provide, in this abstract, updated data on understanding testing trends, treatment patterns, and overall survival in patients with refractory or relapsed FLT3-positive acute myeloid leukemia.

The methods of this analysis used electronic medical record data which were available to ConcertAI through data sharing agreements with community and academic‑based oncology practices, as well as the ASCO CancerLinQ.

Data were approximately 90% drawn from community practices, with data from every part of the country, including every state in the US.

The study design is an ongoing study, and it includes patients diagnosed between January 1, 2015, and April 17, 2020. Of course, this is a retrospective study using electronic medical records. Eligible patients were older than 18 and had a confirmed diagnosis of FLT3-positive acute myeloid leukemia, including more than one relapse/refractory event during that period mentioned. The study variables included FLT3 testing trends, as well as treatment patterns and overall survival.

We have data on 175 patients. Almost half were males. The median length of follow up was limited in the post‑gilteritinib approval period. Gilteritinib was approved in November, 2018, so the follow up for those patients after approval was 9.2 months, while before approval was 15 months. Among those patients, 124 patients were in the pre‑gilteritinib era, while 51 were in the post‑gilteritinib era.

The trends of FLT3 mutation testing showed that the number of patients who were being tested at initial diagnosis increased from 85% in the pre‑gilteritinib cohort to 98% in the post‑gilteritinib cohort, indicating a significant increase in testing. The rate of retesting increased by almost 55%, from 29% to 46% for both cohorts.

For treatment received at the first refractory or relapse event, the use of FLT3 tyrosine kinase inhibitors has been increased by 60%, from 31% in the pre‑gilteritinib era to 49% in the post‑gilteritinib era. The FLT3 TKI monotherapy used was significantly also increased, from 5.6% to 20% across these two cohorts.

Midostaurin and sorafenib were the most commonly used FLT3 inhibitors, as expected in the pre‑gilteritinib era, while gilteritinib became the most commonly used agent in the post‑gilteritinib approval era.

In terms of overall survival, the median overall survival for all patients across the first refractory/relapse event was 13.4 months in the pre‑gilteritinib era, while it was 13 months in the post‑gilteritinib cohort. The difference was not statistically different.

Of course, for patients who went for bone marrow transplantation, the outcomes were better.

Our data basically has some limitations. The completeness of any real‑life data, electronic medical record type of data, is not always complete, and there is a lot of variations. It is possible that testing for patients included in this data set could be different from testing in other settings. This data reflects practices within the community, and that might differ from academic practices.

In conclusion, there was a significant increase in FLT3 TKI use, both as monotherapy and in combination, as well as a decrease in the use of high intensity chemotherapy between the pre‑gilteritinib and post‑gilteritinib eras.

In the 18‑month post‑approval period, FLT3 TKI use increased by 60% with gilteritinib, accounted for more than half of the FLT3 TKI use in the refractory lab setting. Retesting increased by 55% after the availability of gilteritinib. However, this was encouraging but still suboptimal, as there is a need to retest patients as sometimes these mutations could occur subsequent to the initial diagnosis.

Patients who did not undergo bone marrow transplantation, there was an improvement in overall survival in the post‑gilteritinib era, compared to the pre‑gilteritinib era. We will continue to monitor. This is an ongoing study, so we will continue to look at patterns of practice in terms of testing and treatment.

Thank you so much for your attention.

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