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BackgroundTrilaciclib is an intravenous cyclin-dependent kinase 4/6 inhibitor approved to reduce the incidence of chemotherapy-induced myelosuppression in patients with extensive-stage small cell lung cancer (myeloprotection). In a randomized, open-label phase 2 trial in patients with metastatic triple-negative breast cancer (mTNBC), adding trilaciclib prior to gemcitabine/carboplatin (GCb) increased overall survival in both PD-L1–positive and –negative populations versus GCb alone.1 2 We investigated potential immune mechanisms of anti-tumor efficacy among patients who received trilaciclib plus GCb.MethodsPeripheral blood was collected prior to and on treatment for flow cytometric analysis, and total RNA isolated from diagnostic tumor biopsies for sequencing. Differential gene expression analysis between responders and non-responders was based on negative binomial distribution and related pathways identified by Kyoto Encyclopedia of Genes and Genomes pathway analysis. Tumor inflammation signatures and deconvolution-based approaches were used to assess the tumor immune microenvironment. PD-L1 expression was considered positive if ≥1% of the total tumor area contained PD-L1–labelled immune cells (Ventana SP142 assay). Patients were defined as responders (confirmed complete or partial response) or non-responders (stable or progressive disease) according to RECIST criteria.ResultsOf 68 patients who received trilaciclib prior to GCb, tumor response status and RNA sequencing data were available for 51 patients, comprising 24 responders and 27 non-responders. Tumors from responders had 253 differentially expressed genes compared with non-responders. Analysis of immune gene signatures revealed a higher T-cell exhaustion score at baseline among responders versus non-responders (P=0.044).Among patients with PD-L1–positive tumors, responders had a greater peripheral immune response at baseline compared with non-responders, including more T cells (P=0.037; particularly memory CD8 T cells [P=0.042]), and a trend toward fewer myeloid-derived suppressor cells (MDSCs). Additionally, tumors from responders had more dendritic cells (P=0.044) and a trend toward enriched tumor inflammation signatures compared with non-responders.By contrast, among patients with PD-L1–negative tumors, responders had similar peripheral immune populations at baseline compared with PD-L1–negative non-responders, but fewer MDSCs (P=0.016), and a trend toward increased T-cell numbers after two cycles of trilaciclib plus GCb.Responders with both PD-L1–positive and –negative tumors had increased numbers of naïve CD8 T cells after two treatment cycles compared with non-responders.ConclusionsThe data suggest that adding trilaciclib prior to GCb enhances antitumor efficacy by modulating the composition of immune cell subsets. The impact of trilaciclib on changes to the tumor-infiltrating immune response is being further investigated in a phase 3 trial in patients with mTNBC (NCT04799249).AcknowledgementsFlow cytometry and RNA sequencing analyses were performed by Covance, Inc., and Q2 Laboratory Solutions, respectively.Trial Registration www.clinicaltrials.govNCT02978716ReferencesTan AR, Wright GS, Thummala AR, Danso MA, Popovic L, Pluard TJ, Han HS, Vojnović Ž, Vasev N, Ma L, Richards DA, Wilks ST, Milenković D, Yang Z, Antal JM, Morris SR, O’Shaughnessy J. Trilaciclib plus chemotherapy versus chemotherapy alone in patients with metastatic triple-negative breast cancer: a multicentre, randomised, open-label, phase 2 trial. Lancet Oncol 2019;20(11):1587–1601.O’Shaughnessy J, Wright GS, Thummala AR, Danso MA, Popovic L, Pluard TJ, Han HS, Vojnović Ž, Vasev N, Ma L, Richards DA, Wilks ST, Milenković D, Xiao J, Sorrentino JA, Horton J, Tan AR. Abstract PD1-06: trilaciclib improves overall survival when given with gemcitabine/carboplatin in patients with metastatic triple-negative breast cancer: final analysis of a randomized phase 2 trial. Cancer Res 2021;81(4 Supplement):PD1-06.Ethics ApprovalThe study protocol and all associated amendments and study-related materials were approved by the institutional review board or independent ethics committee of each investigational site.

In an effort to identify tumor-associated proteins from plasma of tumor-bearing mice that may be used as diagnostic biomarkers, we developed a strategy that combines a tumor xenotransplantation model in nude mice with comparative proteomic technology. Five human cancer cell lines (SC-M1, HONE-1, CC-M1, OECM1, GBM 8401) derived from stomach, nasopharyngeal, colon, oral and brain cancers were subcutaneously inoculated into nude mice and compared to control nude mice injected with phosphate-buffered saline. One month later, plasma from mice inoculated with cancer cells was collected for proteomic analysis using two-dimensional gel electrophoresis (2-DE) and mass spectrometry (MS). Comparison of plasma 2-DE maps from tumor-bearing mice with those produced from control mice revealed the overexpression of several mouse acute phase proteins (APPs) such as haptoglobin. Another APP, serum amyloid A (SAA), was found only in mice bearing tumors induced by the stomach cancer cell line SC-M1, which has not previously been demonstrated in xenotransplatation experiment. Furthermore, by using immunohistochemistry, SAA and haptoglobin were found to originate from the mouse hosts and not from the human cancer cell line donors. The protein alterations were further confirmed on patients with stomach cancers where up-regulated levels of SAA were also observed. These results indicate that APPs may be used as nonspecific tumor-associated serum markers. SAA in particular may serve as a potential marker for detecting stomach cancer. Taken together, the combination of the xenotransplatation model in nude mice and proteomics analysis provided a valuable impact for clinical applications in cancer diagnostics. In addition, our findings demonstrate that a panel of APPs might serve as screening biomarkers for early cancer detection.

Objectives: To analyse the importance of sequence variations in the internal transcribed spacer (ITS) regions 1 and 2 of the nuclear rRNA operon in AIDS patients with Pneumocystis carinii pneumonia (PCP). Design and methods: ITS 1 and 2 genotypes were determined in 162 bronchoalveolar lavage samples from 130 patients participating in a prospective cohort study of PCP. Results: A total of 49 different ITS genotypes were detected. ITS genotype was not associated with the clinical severity or outcome of PCP. In 37 of 162 (23%) samples infection with two or more genotypes was observed. A genotype switch was detected in six of 10 patients (60%) with recurrent episodes of PCP. However, genotype changes were also seen in 10 of 19 patients (53%) who had repeated bronchoscopies within the same episode of PCP. The same ITS type was observed twice in 13 (46%) of the 28 patients with repeat bronchoscopies during single or recurrent episodes of pneumonia, but in only 14 of 81 (17%) randomly selected pairs (P < 0.01). Conclusion: Although the detection of ITS genotypes is not a random event, changes in genotype can be detected in a single episode of disease, with 23% of PCP patients being infected with more than one P carinii genotype, thus complicating the use of this locus as a genetic marker to separate new infection from the reactivation of latent infection. ITS genotypes are not associated with the clinical severity of PCP.

CD4 T cells are vital in regulating CD8 T cell responses during chronic viral infections. Notably, the hallmark of HIV infection is the severe loss of CD4 T cells resulting in defective CD8 T cell responses. One consequence of CD4 depletion following HIV infection is the loss of interleukin-21 (IL-21) production by the CD4 T cells, which has been demonstrated to be a critical factor in promoting viral control in murine studies. However, it is unknown whether IL-21 can rescue the exhausted CD8 T cells in chronically infected HIV+ patients. In this study we build upon novel murine studies to demonstrate a key role for IL-21 in improving CD8 T cell responses in PBMC from chronically infected HIV patients. To determine whether IL-21 can rescue exhausted CD8 T cells, PBMCs from HIV patients with viral loads > 10,000 RNA copies/mL were incubated with IL-21. Following re-stimulation with overlapping Gag-peptide, IL-21 enhanced the production of IFN-γ by CD8 T cells although no effect was observed on IL-2 or TNF-α production. In addition, an increase in the central memory (CD45RO+CD27+) population was observed with IL-21 culture along with higher MFI of Bcl-6 levels. Interestingly, IL-21 cultured CD8 T cells expressed higher MFI of PD-1 even though CD8 T cell function was enhanced. Significantly, these results provide an approach in which IL-21 can be potentially used to enhance CD8 T cell responses in chronically infected HIV patients, whose CD4 counts are low or defective.