Circulating tumor DNA to investigate resistance mechanism and clone evolution of ALK TKI treated lung adenocarcinoma.

3011 Background: Sequential treatment with first-, second-generation ALK TKI followed by third-generation TKI (lorlatinib) have been widely applied to ALK-positive lung cancer. However, acquired resistance is often driven by secondary ALK mutations, which are needed to be further explored. Circulating tumor DNA, a non-invasive approach, can detect tumor-derived DNA from multiple metastatic sites and has become a promising strategy for assessing the genetic evolution of tumors and analyzing TKI resistance. Methods: Post-progression plasma specimens were collected and sequenced with a targeted gene panel from a total of 116 patients underwent ALK TKI treatment with from February 2014 to April 2020. The ALK TKIs administrated in this cohort included crizotinib (first-generation), ceritinib (second-generation), alectinib (second-generation), brigatinib (second-generation), ensartinib (second-generation) and lorlatinib (third-generation). Results: In this ALK-positive lung adenocarcinoma cohort, 49.1% were female and the rest were male with a median age of 52 (range 20 to 79). More than half of patients received more than one line of ALK TKI treatment. The most frequent ALK fusion type is EML4-ALK including EML4-ALK v1(E13; A20, 37/116, 31.9%) and EML4-ALKv3(E6a/b; A20, 49/116, 42.2%). TP53 (29.1%, 41/141) was the most frequently mutated gene other than ALK. Frequently identified secondary mutations in patients progressing on ALK inhibitors were ALK mutations L1196M and G1202R. ALK G1202R was more common in patient with v3 fusion than in v1 (25.8% vs 0%; P<.001) while ALK L1196M was more common in v1 than in v3 (20.8% vs 3.2%; P=.005). Meanwhile, G1202R was identified at higher ratio in patients progressed on second-generation ALK TKI than first- and third-generation ALK TKI (11.3% vs 0% and 9.1%) whereas L1196M was more found in patients progressed on first-generation ALK TKI (9.1% vs 1.9% and 4.5%). Other identified secondary mutations were ALK F1174C/V/L, E1210K/Q, D1269A, D1203N and L1122M/V. Compound ALK mutations (≥2 concurrent ALK mutations) were more common in patients relapsed on third-generation ALK TKI lorlatinib (36.4%) compared to first- (12.1%) and second-generation (20.8%) ALK TKIs. Using serial plasma specimens, clone evolution analysis showed that five patients developed compound ALK mutations after sequential ALK TKI treatments and two novel ALK compound lorlatinib-resistant mutations D1203N+I1171N and F1174C+G1202R were identified. Conclusions: Genotyping of sequential post-progression plasma specimens reveals that treatment with sequential first-, second-, and third-generation ALK inhibitors can accelerate the accumulation of ALK resistance mutations and may lead to treatment-refractory compound ALK mutations. The selection for optimal first-line TKI is very important to achieve a more efficacious long-term strategy and prevent the emergence of on-target resistance.

CXCL1 Clone Evolution Induced by the HDAC Inhibitor Belinostat Might Be a Favorable Prognostic Indicator in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is the most lethal subtype of breast cancer due to its lack of treatment options. Patients with TNBC frequently develop resistance to chemotherapy. As epigenetic-based antineoplastic drugs, histone deacetylase inhibitors (HDACis) have achieved particular efficacy in lymphoma but are less efficacious in solid tumors, and the resistance mechanism remains poorly understood. In this study, the GSE129944 microarray dataset from the Gene Expression Omnibus database was downloaded, and fold changes at the transcriptome level of a TNBC line (MDA-MB-231) after treatment with belinostat were identified. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were used to identify the critical biological processes. Construction and analysis of the protein-protein interaction (PPI) network were performed to screen candidate genes related to cancer prognosis. A total of 465 DEGs were identified, including 240 downregulated and 225 upregulated genes. The cytokine-cytokine receptor pathway was identified as being significantly changed. Furthermore, the expression of CXCL1 was implicated as a favorable factor in the overall survival of breast cancer patients. With in vitro approaches, we also showed that belinostat could induce the expression of CXCL1 in another 2 TNBC cell lines (BT-549 and HCC-1937). We speculate that belinostat-induced CXCL1 expression could be one of the results of the stress clone evolution of cells after HDACi treatment. These findings provide new insights into clone evolution during HDACi treatment, which might guide us to a novel perspective that various mutation-targeted treatments should be implemented during the whole treatment cycle.

Immunotherapeutic strategies targeting B cell maturation antigen in multiple myeloma

Multiple myeloma (MM) is the second most common hematologic malignancy, and is characterized by the clonal expansion of malignant plasma cells. Despite the recent improvement in patient outcome due to the use of novel therapeutic agents and stem cell transplantation, all patients eventually relapse due to clone evolution. B cell maturation antigen (BCMA) is highly expressed in and specific for MM cells, and has been implicated in the pathogenesis as well as treatment development for MM. In this review, we will summarize representative anti-BCMA immune therapeutic strategies, including BCMA-targeted vaccines, anti-BCMA antibodies and BCMA-targeted CAR cells. Combination of different immunotherapeutic strategies of targeting BCMA, multi-target immune therapeutic strategies, and adding immune modulatory agents to normalize anti-MM immune system in minimal residual disease (MRD) negative patients, will also be discussed.

Staphylococcus capitis isolated from bloodstream infections: a nationwide 3-month survey in 38 neonatal intensive care units

To increase the knowledge about S. capitis in the neonatal setting, we conducted a nationwide 3-month survey in 38 neonatal intensive care units (NICUs) covering 56.6% of French NICU beds. We demonstrated 14.2% of S. capitis BSI (S.capBSI) among nosocomial BSIs. S.capBSI incidence rate was 0.59 per 1000 patient-days. A total of 55.0% of the S.capBSIs were late onset catheter-related BSIs. The S. capitis strains infected preterm babies (median gestational age 26 weeks, median birth weight 855 g). They were resistant to methicillin and aminoglycosides and belonged to the NRCS-A clone. Evolution was favorable in all but one case, following vancomycin treatment.