No Data to Compare BsAbs and CAR T-Cells Directly
Both agreed that there have been no trials directly comparing a BsAb therapy vs CAR T cells, so there is no definitive answer, and Landsburg was reluctant to take a hard line on reserving BsAbs until after CAR T-cell therapy has been tried.
“Because BsAbs and CAR Ts are approved in the third-line setting, you might consider debulking a patient getting ready for a CAR T with a bispecific,” Landsburg said. However, he acknowledged that the next step becomes complex if patients achieved a complete response after just a few BsAb doses.
“Do you stop what is already working?” Landsburg asked rhetorically, suggesting that the best way forward is not always clear.
For R/R FL, currently there are three approved products: axicabtagene ciloleucel (Yescarta), tisagenlecleucel (Kymriah), and lisocabtagene maraleucel (Breyanzi). The entry criteria and design of the three pivotal trials differed, so their specific indications vary. Looking across the trials, Landsburg suggested that there might be differences in activity as defined by objective response rates or risk for cytokine release syndrome, but these remain theoretical without head-to-head comparisons.
“My suspicion is we are going to see very similar — quote, unquote — long-term survival curves for patients treated with any of these therapies,” he said, noting that progression-free survival at 3 years has been in the vicinity of 50% for the trials that have had long enough follow-up to judge.
Rather than trying to pick the best agent, he suggested that it makes more sense now to concentrate on strategies to improve response irrespective of CAR T-cell product; these include paying attention to total metabolic tumor volume at the time of infusion, optimizing bridging therapies, and thinking about T-cell fitness, which might be impaired in some patients by recent exposure to bendamustine.
Overall, with multiple ongoing studies with both CAR T-cell therapies and BsAbs in R/R FL — as well with targeted small-molecule agents and immunomodulatory drugs — all of the debate participants acknowledged that choices in R/R FL will evolve.
“I actually think that combinations will be the future,” Wagner-Johnston said. Singling out tazemetostat and a BsAb and one approach that seems promising, she also predicted that some of the therapies in advanced disease are likely to be moved forward to earlier stages of FL therapy.
Rhodes reported ties with AbbVie, AstraZeneca, ADC Therapeutics, BeiGene, Bristol Myers Squibb, Epizyme, Genentech, Genmab, Janssen, Loxo Oncology, MorphoSys, Pharmacyclics, and Pfizer. Wagner-Johnston disclosed relationships with Cuno Science, Dava Oncology, Epizyme, Grünenthal, Karyopharm, and Seagen. Landsburg reported ties with ADC Therapeutics, Calithera, Curis, Epizyme, Karyopharm, MorphoSys, and Novartis.
A version of this article appeared on Medscape.com.