Multiparameter immunohistochemistry analysis of HIV DNA, RNA and immune checkpoints in lymph node tissue.

The main barrier to a cure for HIV is the persistence of long-lived and proliferating latently infected CD4+ T-cells despite antiretroviral therapy (ART). Latency is well characterized in multiple CD4+ T-cell subsets, however, the contribution of regulatory T-cells (Tregs) expressing FoxP3 as well as immune checkpoints (ICs) PD-1 and CTLA-4 as targets for productive and latent HIV infection in people living with HIV on suppressive ART is less well defined. We used multiplex detection of HIV DNA and RNA with immunohistochemistry (mIHC) on formalin-fixed paraffin embedded (FFPE) cells to simultaneously detect HIV RNA and DNA and cellular markers. HIV DNA and RNA were detected by in situ hybridization (ISH) (RNA/DNAscope) and IHC was used to detect cellular markers (CD4, PD-1, FoxP3, and CTLA-4) by incorporating the tyramide system amplification (TSA) system. We evaluated latently infected cell lines, a primary cell model of HIV latency and excisional lymph node (LN) biopsies collected from people living with HIV (PLWH) on and off ART. We clearly detected infected cells that coexpressed HIV RNA and DNA (active replication) and DNA only (latently infected cells) in combination with IHC markers in the in vitro infection model as well as LN tissue from PLWH both on and off ART. Combining ISH targeting HIV RNA and DNA with IHC provides a platform to detect and quantify HIV persistence within cells identified by multiple markers in tissue samples from PLWH on ART or to study HIV latency.

Programmed death ligand-1 (PD-L1) as a predictive marker for immunotherapy in solid tumours: a guide to immunohistochemistry implementation and interpretation.

Immunotherapy with checkpoint inhibitors is well established as an effective treatment for non-small cell lung cancer and melanoma. The list of approved indications for treatment with PD-1/PD-L1 checkpoint inhibitors is growing rapidly as clinical trials continue to show their efficacy in patients with a wide range of solid tumours. Clinical trials have used a variety of PD-L1 immunohistochemical assays to evaluate PD-L1 expression on tumour cells, immune cells or both as a potential biomarker to predict response to immunotherapy. Requests to pathologists for PD-L1 testing to guide choice of therapy are rapidly becoming commonplace. Thus, pathologists need to be aware of the different PD-L1 assays, methods of evaluation in different tumour types and the impact of the results on therapeutic decisions. This review discusses the key practical issues relating to the implementation of PD-L1 testing for solid tumours in a pathology laboratory, including evidence for PD-L1 testing, different assay types, the potential interchangeability of PD-L1 antibody clones and staining platforms, scoring criteria for PD-L1, validation, quality assurance, and pitfalls in PD-L1 assessment. This review also explores PD-L1 IHC in solid tumours including non-small cell lung carcinoma, head and neck carcinoma, triple negative breast carcinoma, melanoma, renal cell carcinoma, urothelial carcinoma, gastric and gastroesophageal carcinoma, colorectal carcinoma, hepatocellular carcinoma, and endometrial carcinoma. The review aims to provide pathologists with a practical guide to the implementation and interpretation of PD-L1 testing by immunohistochemistry.

Stability of nivolumab in its original vials after opening and handing in normal saline bag for intravenous infusion.

OBJECTIVES: Nivolumab is an anti-programmed cell death-1 monoclonal antibody, approved for numerous indications in oncohaematological cancers. It is available as solution for infusion at 10 mg/ml. In accordance with the Summary of Product Characteristics (SmPCs), the product is stable for 24 h at 2-8 °C after dilution. However, to anticipate the needs and constraints related to the handling of the product, the aim was to obtain additional information that will contribute to the risk assessment in case of deviation. Potential changes in the stability of Opdivo® leftovers (10 mg/ml) and diluted nivolumab in normal saline solution (2 mg/ml) over a period exceeding 24 h, at different temperatures and after freezing/thawing cycles were studied. METHODS: Turbidimetry, Ultraviolet (UV)-spectroscopy, dynamic light scattering and chromatography were used to evaluate physicochemical stability. Potential pharmacological variations were monitored in vitro by a functional binding inhibition method. RESULTS: No change was detected after 1 month of storage at 2-8 °C neither after 7 days at 40 °C. Although slight changes were detected only after 3 months under 2-8 °C, major changes were found for the same period of time at 40 °C (variants in the distribution profile, slight increase in oligomers and fragments and UV spectral modifications). Physical instability was observed upon 3 freeze/thaw cycles, with the appearance of a new protein population associated with an increase in polydispersity index. CONCLUSION: In conclusion, our results provide additional rationale to the SmPCs, regarding the use of leftovers, reassignment of bags, pre-preparation or breaking the cold chain for Nivolumab.

A measuring method for occupancy of immune checkpoint inhibitors in the cell surface.

Monoclonal antibodies, including immune-checkpoint inhibitors, are becoming popular in treatments of many cancers and connective tissue diseases. However, little is known about how long the antibodies combine with antigens on targeted cells or how this duration of binding associates with therapeutic efficacy or potential adverse events. Here, we show the principle and the results of a feasible method for measuring the antibodies' occupancy on the targeted cells using two different detecting antibodies in conjunction with different fluorochromes. Nivolumab occupancy was measured using two detecting antibodies, MIH4 and EH12.2, which are commercially available in vitro (programmed cell death-1 [PD-1] expressing the cell line MIT9 and human T cells) and in T cells from patients treated with nivolumab. Our method has potential for use as a simple and feasible monitoring system in the clinical setting.