A Nature Biotechnology paper described engineered inhalable exosomes carrying a bispecific T‑cell activator that, when delivered to the lung, activated antitumor T cells and suppressed pembrolizumab‑resistant metastatic melanoma in vivo. The platform targets the tumor microenvironment and aims to overcome immune checkpoint inhibitor resistance by recruiting and activating T cells locally. Authors reported chronic sensing, programmable stimulation and efficacy in preclinical models, positioning inhalable exosome platforms as a potential new modality for hard‑to‑treat metastatic disease.