Rechallenge of afatinib for EGFR-mutated non-small cell lung cancer previously treated with osimertinib: a multicenter phase II trial protocol (REAL study).

Background: Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have revolutionized the treatment of advanced non-small cell lung cancer (NSCLC) and contributed to the development of precision medicine. Osimertinib is a standard first-line (1L) treatment for EGFR-mutated NSCLC and has demonstrated superior survival benefits over previous-generation TKIs. However, resistance to osimertinib is nearly inevitable, and subsequent treatment strategies remain unmet medical needs in this setting. Afatinib, a second-generation EGFR-TKI, exhibits activity against certain uncommon EGFR mutation types in the 1L setting. There are a few case reports on the efficacy of afatinib against EGFR-dependent resistance after osimertinib treatment, although these have not been prospectively investigated. Methods: The present phase II, single-arm multicenter trial aims to verify the efficacy and safety of afatinib rechallenge after 1L osimertinib resistance. Patients (aged ≥20 years) with advanced or recurrent non-squamous NSCLC harboring drug-sensitive EGFR mutations (deletion of exon 19 or L858R) who were previously treated with 1L osimertinib and second-line chemotherapy other than TKIs are considered eligible. Undergoing next-generation sequence-based comprehensive genomic profiling is one of the key inclusion criteria. The primary endpoint is the objective response rate; the secondary endpoints are progression-free survival, overall survival, and tolerability. Thirty patients will be recruited in December 2023. Discussion: The results of this study may promote incorporating afatinib rechallenge into the treatment sequence after 1L osimertinib resistance, a setting in which concrete evidence has not been yet established. Registration: UMIN Clinical Trial Registry: UMIN000049225.

Systematic screening and identification of antigens recognized by monoclonal antibodies raised against the developing lateral olfactory tract.

During development, olfactory bulb axons navigate a complex microenvironment composed of myriad molecules to construct a bundle called the lateral olfactory tract. The axons themselves also express thousands of different molecules. In the present study, we produced and characterized six monoclonal antibodies that label the lateral olfactory tract and its surroundings in a unique pattern. The labeling profiles suggested that the antigen molecules recognized by each antibody are heterogeneously distributed around the developing lateral olfactory tract. We developed an efficient screening method to identify the antigen molecules by combining expression of a cDNA library in COS-7 cells and the subsequent immunohistochemical staining of the cells. The systematic screening successfully identified specific cDNA clones for all of the monoclonal antibodies, which highly probably coded for the antigen molecules, and therefore unveiled the molecular nature of local components that embrace the developing lateral olfactory tract in mice.

Expression of Nogo protein by growing axons in the developing nervous system.

We produced monoclonal antibody NG1 that strongly binds growing axons in the developing nervous system of mice. This antibody intensely labeled the growth cone of cultured neurons. Although these immunostaining patterns suggested the association of growing axons with the antigen recognized by this antibody, the antigen was identified as Nogo protein, an axonal repulsive factor isolated from the myelin. On the basis of this unexpected finding, we discuss the possible functions of Nogo in the developing nervous system.

Mosaic development of the olfactory cortex with Pax6-dependent and -independent components.

The olfactory cortex is the target area of olfactory bulb axons and is suggested to be derived from neuroepithelial progenitors of various ventricular domains during development. In the present study, we examined the development of the olfactory cortex, using the newly developed monoclonal antibody (mAb) 9-4c, which recognizes reticulon 1-A and -B. The mAb labeled neuroepithelial progenitors at the pallio-subpallial boundary (PSB) and their putative descendants in the deep layers of the olfactory cortex. In the Pax6 mutant embryo, labeling at the PSB was specifically lacking, and the number of immunopositive cells in the olfactory cortex was markedly reduced. In contrast, the guidepost neurons of olfactory bulb axons, lot cells, developed relatively normally in the superficial layer of the olfactory cortex in the mutant embryo. These guidepost neurons have been recently shown to originate in the pallium and eventually guide the initial projection of olfactory bulb axons. The olfactory bulb projection in the Pax6 mutant embryo also suggested the dualistic nature of the olfactory cortex development; the initial projection of olfactory bulb axons developed relatively normally, whereas the final projection of their collateral branches was severely defective.