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Abstract Background Folate receptor alpha (FRα) overexpression is seen in many cancers. Radioligand therapy (RLT) has emerged as a promising tool to target FRα and has been investigated previously, but further progression was limited due to high kidney retention and, subsequently, toxicity. To circumvent this, we present here the development of a [131I]I-GMIB-conjugated anti-human FRα (hFRα) single-domain antibody (sdAb), with intrinsically fast renal clearance and concomitant low kidney retention. We report the hit-to-lead development of an anti-hFRα sdAb. We evaluated its potential in vitro and assessed its targeting ability using SPECT imaging in hFRα-knockin and tumour-bearing mice. The toxicity and therapeutic efficacy of the [131I]I-GMIB-sdAb were investigated in mouse models. Results The lead anti-hFRα sdAb 2BD42 was developed with picomolar affinities, low koff, and radiolabelled using [131I]I with yields of > 41% and purity > 99%. [131I]I-GMIB-2BD42 retained tumour uptake (> 5%IA/g at 1 h p.i. and > 1.5%IA/g at 24 h p.i.) and fast kidney clearance (

Immune checkpoint inhibition (ICI) is a promising cancer therapy, which has progressed rapidly from a preclinical concept to clinical implementation. Commonly considered targets in ICI are CTLA-4, PD-1/PD-L1, and LAG-3, and the list grows. As ICI is generally only beneficial for a subset of patients, there is a need to select patients that are eligible for therapy as well as to monitor therapy response. There is growing interest to do this noninvasively, by molecular imaging with target-specific tracers. To this day, noninvasive imaging has focused on CTLA-4 and PD-1/PD-L1, while there is no noninvasive tool available to accurately assess LAG-3 expression in vivo. In this proof-of-concept study, we developed nanobodies, the smallest functional fragments from camelid heavy chain-only antibodies, to noninvasively evaluate mouse LAG-3 expression using single positron emission computed tomography (SPECT)/CT imaging. The in vitro characterization of 114 nanobodies led to the selection of nine nanobodies binding to mouse LAG-3. The injection of 99mTechnetium-labeled nanobodies in healthy mice showed specific uptake in immune peripheral organs like the spleen and lymph nodes, which was not observed in LAG-3 gene knock-out mice. Moreover, nanobody uptake could be visualized using SPECT/CT and correlated to the presence of LAG-3 as assessed in flow cytometry and immunohistochemistry. SPECT/CT scans of tumor bearing mice further confirmed the diagnostic potential of the nanobodies. These findings substantiate the approach to use nanobodies as a tool to image inhibitory immune checkpoints in the tumor environment.

Background: Interleukin-27 is a heterodimeric cytokine belonging to IL-12 and IL-23 families, secreted by Antigen Presenting Cells(APCs) .The IL-27 is composed of 2 subunits: Epstein-Barr virus induced gene 3 (EBI3) and p28. IL-27 is an anti-inflammatory cytokine which has an inhibitory effect on Th17 population and suppress the IL-17 expression. It is suggested that IL-27 could be a potent drug candidate for treating auto immune diseases.Methods: The IL-27 subunit genes were constructed into plasmid vectors, they sub-cloned into pETDeut-1an expression vector in restriction sites of BamHI, SacI and NotI. Subsequently the induction was done by IPTG and the recombinant proteins were confirmed by SDS-PAGE and Western Blot analysis using anti His-tag antibody.Results: The 28kDa and 25kDa protein bands were observed on SDS-PAGE and finally confirmed by Western blot technique.