In the study, investigators led by Thomas examined outcomes from a clinical trial testing bintrafusp alfa, an experimental therapy that simultaneously blocks the immune checkpoint protein PD-L1 and the signaling molecule TGF-beta in patients with relapsed small cell lung cancer and related neuroendocrine cancers.

They found that while some patients experienced a favorable response to treatment, others developed hyperprogressive disease, a phenomenon in which tumors grow faster after treatment begins. Among 34 patients evaluated in the study, 18% experienced significant tumor shrinkage, while 38% experienced hyperprogressive disease.