Continuous measurements of pressure and temperature within the intracranial, intraocular, and intravascular spaces provide essential diagnostic information for the treatment of traumatic brain injury, glaucoma, and cardiovascular diseases, respectively. Optical sensors are attractive because of their inherent compatibility with magnetic resonance imaging (MRI). Existing implantable optical components use permanent, nonresorbable materials that must be surgically extracted after use. Bioresorbable alternatives, introduced here, bypass this requirement, thereby eliminating the costs and risks of surgeries. Here, millimeter-scale bioresorbable Fabry-Perot interferometers and two dimensional photonic crystal structures enable precise, continuous measurements of pressure and temperature. Combined mechanical and optical simulations reveal the fundamental sensing mechanisms. In vitro studies and histopathological evaluations quantify the measurement accuracies, operational lifetimes, and biocompatibility of these systems. In vivo demonstrations establish clinically relevant performance attributes. The materials, device designs, and fabrication approaches outlined here establish broad foundational capabilities for diverse classes of bioresorbable optical sensors.

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Programmed cell death protein 1 (PD-1) blocking agents are novel immunotherapeutics used for treatment of advanced-stage malignancies. They have shown promise in the treatment of several malignancies, with greater efficacy and better tolerability than cytotoxic T-lymphocyte antigen 4 (CTLA-4) blocking agents. However, as with anti-CTLA-4 agents, clinically significant colitis remains an important complication. Although there is growing awareness of the histopathologic features of anti-CTLA-4 therapy, there is little information on the pathologic features of anti-PD-1 colitis. We describe here the histopathologic findings in 8 patients who developed colitis while on anti-PD-1 monotherapy. The most common pattern of injury observed (5/8 cases) was an active colitis with neutrophilic crypt microabscesses and with prominent crypt epithelial cell apoptosis and crypt atrophy/dropout. These latter features are reminiscent of other colitides with prominent apoptosis such as acute graft-versus-host disease or certain drug-induced colitides. The remainder of cases (3/8) showed a lymphocytic colitis-like pattern, characterized by increased intraepithelial lymphocytes and surface epithelial injury. Apoptosis was also often increased in these cases but crypt atrophy/dropout was not present. In patients who experienced recurrence of anti-PD-1 colitis, histologic features were similar to the initial insult but, in addition, features of chronicity developed that mimicked inflammatory bowel disease (basal lymphoplasmacytosis and crypt architectural irregularity, and Paneth cell metaplasia in 1 case). Awareness of the clinical scenario, however, should allow pathologists to suggest anti-PD-1 colitis. Interestingly, recurrent colitis was observed in patients who had been off anti-PD-1 therapy for many months. As anti-PD-1 agents are increasingly used in oncology, we present this series to increase awareness of anti-PD-1 colitis among pathologists, to facilitate its timely diagnosis and treatment.