Doctors treating lymphoma patients with the CAR-T therapy Yescarta in the “real world” are seeing results that are slightly worse than data collected in the pivotal clinical trial conducted by Kite Pharma, now a part of Gilead Sciences. But the analysis may have been affected by the inclusion of sicker patients who would have been denied entry into the Yescarta clinical trial.

In one of two real-world retrospective studies presented today, researchers collected outcomes from 104 lymphoma patients treated with Yescarta at six academic hospitals since the CAR-T was approved. The results: an overall response rate of 71 percent with a complete response rate of 44 percent, according to lead author Dr. Caron Jacobson from Boston’s Dana-Farber Cancer Institute.

Yescarta was approved based on a clinical trial called Zuma-1 that demonstrated an 82 percent overall response rate, including a 54 percent complete response rate. The frequency and severity of cytokine release syndrome and neurological toxicity — the most worrisome side effects of CAR-T treatment — were similar between the real-world analysis and the Zuma-1 results. The durability of responses was also nearly identical.

Jacobson said 60 percent of the patients included in her real-world analysis would not have been eligible for the Zuma-1 trial. Many of these patients had more advanced disease or poorer prognostic factors before treatment. Taken those differences into account, she views the comparable Yescarta response rates to be “similar and encouraging.”

Additional data and longer follow-up is being collected from patients to help identify biomarkers that might one day help doctors better predict which patients will respond best to CAR-T therapy, Jacobson said.