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Abstract Background Immune checkpoint inhibitors, including those against programmed cell death protein-1 (PD-1) or its ligand (PD-L1), are routinely used to treat non-small cell lung cancer (NSCLC). PD-L1 is a validated prognostic and predictive immunohistochemical biomarker of anti-PD-1/PD-L1 therapy but displays temporospatial heterogeneity of expression. Non-invasive radiopharmaceutical techniques, including technetium-99m [99mTc]-labelled anti-PD-L1 single-domain antibody (NM-01) SPECT/CT, have the potential to improve the predictive value of PD-L1 assessment. This study aims to determine the inter- and intra-rater agreement of the quantitative measurement of [99mTc]NM-01 SPECT/CT in NSCLC. Methods Participants (n = 14) with untreated advanced NSCLC underwent [99mTc]NM-01 SPECT/CT at baseline (n = 3) or at baseline plus 9-week follow-up (n = 11). [99mTc]NM-01 uptake (of primary lung, lymph node, thoracic and distant metastases, and healthy reference tissues) was measured using SUVmax and malignant lesion-to-blood pool ratios with Siemens xSPECT Broad Quantification software by three independent raters. Intraclass correlation coefficients (ICC) were calculated and Bland–Altman plot analysis performed to determine inter- and intra-rater agreement. Results There was excellent inter-rater agreement of manual freehand SUVmax scores of primary lung tumour (T; n = 25; ICC 1.00; 95% CI 0.99–1.00), individual lymph node metastases (LN; n = 56; ICC 0.97; 95% CI 0.95–0.98), thoracic metastases (ThMet; n = 9; ICC 0.94; 95% CI 0.83–0.99) and distant metastases (DisMet; n = 21; ICC 0.91; 95% CI 0.83–0.96). The inter-rater ICCs of tumour-to-blood pool (T:BP), LN:BP, ThMet:BP and DisMet:BP measures of [99mTc]NM-01 uptake also demonstrated good or excellent agreement. Manual freehand scoring of T, LN, ThMet, DisMet and their ratios using [99mTc]NM-01 SPECT/CT following a 28-day interval was consistent for all raters with good or excellent intra-rater agreement demonstrated (ICCs range 0.86–1.00). Conclusion Quantitative assessment of [99mTc]NM-01 SPECT/CT in NSCLC, using SUVmax of malignant primary or metastatic lesions and their ratios with healthy reference tissues, demonstrated good or excellent inter- and intra-rater agreement in this study. Further validation with ongoing and future larger cohort studies is now warranted. Clinical trial registration ClinicalTrials.gov identifier no. NCT04436406 (registered 18th June 2020; available at https://clinicaltrials.gov/ct2/show/NCT04436406 ) and NCT04992715 (registered 5th August 2021; available at https://clinicaltrials.gov/ct2/show/NCT04992715 ).

Single-domain antibodies, also known as nanobodies, are broadly important for studying the structure and conformational states of several classes of proteins, including membrane proteins, enzymes, and amyloidogenic proteins. Conformational nanobodies specific for aggregated conformations of amyloidogenic proteins are particularly needed to better target and study aggregates associated with a growing class of associated diseases, especially neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. However, there are few reported nanobodies with both conformational and sequence specificity for amyloid aggregates, especially for large and complex proteins such as the tau protein associated with Alzheimer's disease, due to difficulties in selecting nanobodies that bind to complex aggregated proteins. Here, we report the selection of conformational nanobodies that selectively recognize aggregated (fibrillar) tau relative to soluble (monomeric) tau. Notably, we demonstrate that these nanobodies can be directly isolated from immune libraries using quantitative flow cytometric sorting of yeast-displayed libraries against tau aggregates conjugated to quantum dots, and this process eliminates the need for secondary nanobody screening. The isolated nanobodies demonstrate conformational specificity for tau aggregates in brain samples from both a transgenic mouse model and human tauopathies. We expect that our facile approach will be broadly useful for isolating conformational nanobodies against diverse amyloid aggregates and other complex antigens. [ABSTRACT FROM AUTHOR]

Background: Immune checkpoint inhibitors, including those against programmed cell death protein-1 (PD-1) or its ligand (PD-L1), are routinely used to treat non-small cell lung cancer (NSCLC). PD-L1 is a validated prognostic and predictive immunohistochemical biomarker of anti-PD-1/PD-L1 therapy but displays temporospatial heterogeneity of expression. Non-invasive radiopharmaceutical techniques, including technetium-99m [99mTc]-labelled anti-PD-L1 single-domain antibody (NM-01) SPECT/CT, have the potential to improve the predictive value of PD-L1 assessment. This study aims to determine the inter- and intra-rater agreement of the quantitative measurement of [99mTc]NM-01 SPECT/CT in NSCLC. Methods: Participants (n = 14) with untreated advanced NSCLC underwent [99mTc]NM-01 SPECT/CT at baseline (n = 3) or at baseline plus 9-week follow-up (n = 11). [99mTc]NM-01 uptake (of primary lung, lymph node, thoracic and distant metastases, and healthy reference tissues) was measured using SUVmax and malignant lesion-to-blood pool ratios with Siemens xSPECT Broad Quantification software by three independent raters. Intraclass correlation coefficients (ICC) were calculated and Bland–Altman plot analysis performed to determine inter- and intra-rater agreement. Results: There was excellent inter-rater agreement of manual freehand SUVmax scores of primary lung tumour (T; n = 25; ICC 1.00; 95% CI 0.99–1.00), individual lymph node metastases (LN; n = 56; ICC 0.97; 95% CI 0.95–0.98), thoracic metastases (ThMet; n = 9; ICC 0.94; 95% CI 0.83–0.99) and distant metastases (DisMet; n = 21; ICC 0.91; 95% CI 0.83–0.96). The inter-rater ICCs of tumour-to-blood pool (T:BP), LN:BP, ThMet:BP and DisMet:BP measures of [99mTc]NM-01 uptake also demonstrated good or excellent agreement. Manual freehand scoring of T, LN, ThMet, DisMet and their ratios using [99mTc]NM-01 SPECT/CT following a 28-day interval was consistent for all raters with good or excellent intra-rater agreement demonstrated (ICCs range 0.86–1.00). Conclusion: Quantitative assessment of [99mTc]NM-01 SPECT/CT in NSCLC, using SUVmax of malignant primary or metastatic lesions and their ratios with healthy reference tissues, demonstrated good or excellent inter- and intra-rater agreement in this study. Further validation with ongoing and future larger cohort studies is now warranted. Clinical trial registration: ClinicalTrials.gov identifier no. NCT04436406 (registered 18th June 2020; available at https://clinicaltrials.gov/ct2/show/NCT04436406) and NCT04992715 (registered 5th August 2021; available at https://clinicaltrials.gov/ct2/show/NCT04992715). [ABSTRACT FROM AUTHOR]

Single-domain antibodies, also known as nanobodies, are broadly important for studying the structure and conformational states of several classes of proteins, including membrane proteins, enzymes, and amyloidogenic proteins. Conformational nanobodies specific for aggregated conformations of amyloidogenic proteins are particularly needed to better target and study aggregates associated with a growing class of associated diseases, especially neurodegenerative disorders such as Alzheimer’s and Parkinson’s diseases. However, there are few reported nanobodies with both conformational and sequence specificity for amyloid aggregates, especially for large and complex proteins such as the tau protein associated with Alzheimer’s disease, due to difficulties in selecting nanobodies that bind to complex aggregated proteins. Here, we report the selection of conformational nanobodies that selectively recognize aggregated (fibrillar) tau relative to soluble (monomeric) tau. Notably, we demonstrate that these nanobodies can be directly isolated from immune libraries using quantitative flow cytometric sorting of yeast-displayed libraries against tau aggregates conjugated to quantum dots, and this process eliminates the need for secondary nanobody screening. The isolated nanobodies demonstrate conformational specificity for tau aggregates in brain samples from both a transgenic mouse model and human tauopathies. We expect that our facile approach will be broadly useful for isolating conformational nanobodies against diverse amyloid aggregates and other complex antigens.

Abstract Purpose Checkpoint inhibition therapy using monoclonal antibodies against programmed cell death protein 1 (PD-1) or its ligand (PD-L1) is now standard management of non-small cell lung cancer (NSCLC). PD-L1 expression is a validated and approved prognostic and predictive biomarker for anti-PD-1/PD-L1 therapy. Technetium-99 m [99mTc]-labelled anti-PD-L1 single-domain antibody (NM-01) SPECT/CT quantification correlates with PD-L1 expression in NSCLC, presenting an opportunity for non-invasive assessment. The aim of this study was to determine the inter- and intraobserver agreement of the quantitative assessment of [99mTc]NM-01 SPECT/CT in NSCLC. Methods [99mTc]NM-01 SPECT/CT studies of 21 consecutive NSCLC participants imaged for the evaluation of PD-L1 expression were analysed. Three independent observers measured maximum counts in a tumour region of interest (ROImax) of primary lung, metastatic lesions and normal tissue references of both 1 and 2 h post-injection (n = 42) anonymised studies using a manual technique. Intraclass correlation coefficients (ICC) were calculated, and Bland–Altman plot analysis was performed to determine inter- and intraobserver agreement. Results Intraclass correlation of primary lung tumour-to-blood pool (T:BP; ICC 0.83, 95% CI 0.73–0.90) and lymph node metastasis-to-blood pool (LN:BP; ICC 0.87, 0.81–0.92) measures of [99mTc]NM-01 uptake was good to excellent between observers. Freehand ROImax of T (ICC 0.94), LN (ICC 0.97), liver (ICC 0.97) and BP (ICC 0.90) reference tissues also demonstrated excellent interobserver agreement. ROImax scoring of healthy lung demonstrated moderate to excellent interobserver agreement (ICC 0.84) and improved when measured consistently at the level of the aortic arch (ICC 0.89). Manual ROImax re-scoring of T, LN, T:BP and LN:BP using [99mTc]NM-01 SPECT/CT following a 42-day interval was consistent with excellent intraobserver agreement (ICC range 0.95–0.97). Conclusion Good to excellent inter- and intraobserver agreement of the quantitative assessment of [99mTc]NM-01 SPECT/CT in NSCLC was demonstrated in this study, including T:BP which has been shown to correlate with PD-L1 status. [99mTc]NM-01 SPECT/CT has the potential to reliably and non-invasively assess PD-L1 expression. Clinical trial registration ClinicalTrials.gov identifier no. NCT02978196. Registered 30th November 2016.

Purpose: Macrophage mannose receptor (MMR, CD206) expressing tumor-associated macrophages (TAM) are protumorigenic and was reported to negatively impact therapy responsiveness and is associated with higher chances of tumor relapse following multiple treatment regimens in preclinical tumor models. Since the distribution of immune cells within the tumor is often heterogeneous, sampling "errors" using tissue biopsies will occur. In order to overcome this limitation, we propose positron emission tomography (PET)/X-ray computed tomography (CT) imaging using 68Ga-labeled anti-MMR single-domain antibody fragment (sdAb) to assess the presence of these protumorigenic TAM.Procedures: Cross-reactive anti-MMR-sdAb was produced according to good manufacturing practice (GMP) and conjugated to p-SCN-Bn-NOTA bifunctional chelator for 68Ga-labeling. Biodistribution and PET/CT studies were performed in wild-type and MMR-deficient 3LL-R tumor-bearing mice. Biodistribution data obtained in mice were extrapolated to calculate radiation dose estimates for the human adult using OLINDA software. A 7-day repeated dose toxicity study for NOTA-anti-MMR-sdAb was performed in healthy mice up to a dose of 1.68 mg/kg.Results: [68Ga]Ga-NOTA-anti-MMR-sdAb was obtained with 76 ± 2 % radiochemical yield, 99 ± 1 % radiochemical purity, and apparent molar activity of 57 ± 11 GBq/μmol. In vivo biodistribution analysis showed fast clearance via the kidneys and retention in MMR-expressing organs and tumor, with tumor-to-blood and tumor-to-muscle ratios of 6.80 ± 0.62 and 5.47 ± 1.82, respectively. The calculated effective dose was 0.027 mSv/MBq and 0.034 mSv/MBq for male and female, respectively, which means that a proposed dose of 185 MBq in humans would yield a radiation dose of 5.0 and 6.3 mSv to male and female patients, respectively. In the toxicity study, no adverse effects were observed.Conclusions: Preclinical validation of [68Ga]Ga-NOTA-anti-MMR-sdAb showed high specific uptake of this tracer in MMR-expressing TAM and organs, with no observed toxicity. [68Ga]Ga-NOTA-anti-MMR-sdAb is ready for a phase I clinical trial. [ABSTRACT FROM AUTHOR]

Highlights: [•] We provide an overview of the diverse chemistries that are used for preparing quantum dot bioconjugates. [•] Polyhistidine-mediated metal-affinity coordination to QD surfaces is described in detail. [•] A variety of modular, chemoselective ligation chemistries that can be applied to QD bioconjugation are described. [•] Applications incorporating various QD-bioconjugates assembled using different chemistries are included. [Copyright &y& Elsevier]

Highlights: [•] Single-domain antibodies with high specificity to human lactoferrin are generated. [•] Generated antibodies are used to efficiently separate human and goat lactoferrins. [•] Single-domain antibody-based ligands can help to separate highly homologous proteins. [ABSTRACT FROM AUTHOR]

Purpose: Checkpoint inhibition therapy using monoclonal antibodies against programmed cell death protein 1 (PD-1) or its ligand (PD-L1) is now standard management of non-small cell lung cancer (NSCLC). PD-L1 expression is a validated and approved prognostic and predictive biomarker for anti-PD-1/PD-L1 therapy. Technetium-99 m [99mTc]-labelled anti-PD-L1 single-domain antibody (NM-01) SPECT/CT quantification correlates with PD-L1 expression in NSCLC, presenting an opportunity for non-invasive assessment. The aim of this study was to determine the inter- and intraobserver agreement of the quantitative assessment of [99mTc]NM-01 SPECT/CT in NSCLC. Methods: [99mTc]NM-01 SPECT/CT studies of 21 consecutive NSCLC participants imaged for the evaluation of PD-L1 expression were analysed. Three independent observers measured maximum counts in a tumour region of interest (ROImax) of primary lung, metastatic lesions and normal tissue references of both 1 and 2 h post-injection (n = 42) anonymised studies using a manual technique. Intraclass correlation coefficients (ICC) were calculated, and Bland–Altman plot analysis was performed to determine inter- and intraobserver agreement. Results: Intraclass correlation of primary lung tumour-to-blood pool (T:BP; ICC 0.83, 95% CI 0.73–0.90) and lymph node metastasis-to-blood pool (LN:BP; ICC 0.87, 0.81–0.92) measures of [99mTc]NM-01 uptake was good to excellent between observers. Freehand ROImax of T (ICC 0.94), LN (ICC 0.97), liver (ICC 0.97) and BP (ICC 0.90) reference tissues also demonstrated excellent interobserver agreement. ROImax scoring of healthy lung demonstrated moderate to excellent interobserver agreement (ICC 0.84) and improved when measured consistently at the level of the aortic arch (ICC 0.89). Manual ROImax re-scoring of T, LN, T:BP and LN:BP using [99mTc]NM-01 SPECT/CT following a 42-day interval was consistent with excellent intraobserver agreement (ICC range 0.95–0.97). Conclusion: Good to excellent inter- and intraobserver agreement of the quantitative assessment of [99mTc]NM-01 SPECT/CT in NSCLC was demonstrated in this study, including T:BP which has been shown to correlate with PD-L1 status. [99mTc]NM-01 SPECT/CT has the potential to reliably and non-invasively assess PD-L1 expression. Clinical trial registration: ClinicalTrials.gov identifier no. NCT02978196. Registered 30th November 2016. [ABSTRACT FROM AUTHOR]

Purpose: Checkpoint inhibition therapy using monoclonal antibodies against programmed cell death protein 1 (PD-1) or its ligand (PD-L1) is now standard management of non-small cell lung cancer (NSCLC). PD-L1 expression is a validated and approved prognostic and predictive biomarker for anti-PD-1/PD-L1 therapy. Technetium-99 m [ 99m Tc]-labelled anti-PD-L1 single-domain antibody (NM-01) SPECT/CT quantification correlates with PD-L1 expression in NSCLC, presenting an opportunity for non-invasive assessment. The aim of this study was to determine the inter- and intraobserver agreement of the quantitative assessment of [ 99m Tc]NM-01 SPECT/CT in NSCLC., Methods: [ 99m Tc]NM-01 SPECT/CT studies of 21 consecutive NSCLC participants imaged for the evaluation of PD-L1 expression were analysed. Three independent observers measured maximum counts in a tumour region of interest (ROI max ) of primary lung, metastatic lesions and normal tissue references of both 1 and 2 h post-injection (n = 42) anonymised studies using a manual technique. Intraclass correlation coefficients (ICC) were calculated, and Bland-Altman plot analysis was performed to determine inter- and intraobserver agreement., Results: Intraclass correlation of primary lung tumour-to-blood pool (T:BP; ICC 0.83, 95% CI 0.73-0.90) and lymph node metastasis-to-blood pool (LN:BP; ICC 0.87, 0.81-0.92) measures of [ 99m Tc]NM-01 uptake was good to excellent between observers. Freehand ROI max of T (ICC 0.94), LN (ICC 0.97), liver (ICC 0.97) and BP (ICC 0.90) reference tissues also demonstrated excellent interobserver agreement. ROI max scoring of healthy lung demonstrated moderate to excellent interobserver agreement (ICC 0.84) and improved when measured consistently at the level of the aortic arch (ICC 0.89). Manual ROI max re-scoring of T, LN, T:BP and LN:BP using [ 99m Tc]NM-01 SPECT/CT following a 42-day interval was consistent with excellent intraobserver agreement (ICC range 0.95-0.97)., Conclusion: Good to excellent inter- and intraobserver agreement of the quantitative assessment of [ 99m Tc]NM-01 SPECT/CT in NSCLC was demonstrated in this study, including T:BP which has been shown to correlate with PD-L1 status. [ 99m Tc]NM-01 SPECT/CT has the potential to reliably and non-invasively assess PD-L1 expression., Clinical Trial Registration: ClinicalTrials.gov identifier no. NCT02978196. Registered 30th November 2016.

Reagents that bind tightly and specifically to biomolecules of interest remain essential in the exploration of biology and in their ultimate application to medicine. Besides ligands for receptors of known specificity, agents commonly used for this purpose are monoclonal antibodies derived from mice, rabbits, and other animals. However, such antibodies can be expensive to produce, challenging to engineer, and are not necessarily stable in the context of the cellular cytoplasm, a reducing environment. Heavy chain-only antibodies, discovered in camelids, have been truncated to yield single-domain antibody fragments (VHHs or nanobodies) that overcome many of these shortcomings. Whereas they are known as crystallization chaperones for membrane proteins or as simple alternatives to conventional antibodies, nanobodies have been applied in settings where the use of standard antibodies or their derivatives would be impractical or impossible. We review recent examples in which the unique properties of nanobodies have been combined with complementary methods, such as chemical functionalization, to provide tools with unique and useful properties., Competing Interests: Conflict of interest—The authors declare that they have no conflicts of interest with the contents of this article., (© 2020 Cheloha et al.)