Plasma-based analysis of ERBB2 mutational status by multiplex digital PCR in a large series of patients with metastatic breast cancer.

Erb-b2 receptor tyrosine kinase 2 (ERBB2)-activating mutations are therapeutically actionable alterations found in various cancers, including metastatic breast cancer (MBC). We developed multiplex digital PCR assays to detect and quantify ERBB2 mutations in circulating tumor DNA from liquid biopsies. We studied the plasma from 272 patients with hormone-receptor-positive, human epidermal growth factor receptor 2-negative (HR+/HER2-) MBC to detect 17 ERBB2 mutations using a screening assay. The assay was developed on the three-color Crystal dPCR™ naica® platform with a two-step strategy for precise mutation identification. We found that nine patients (3.3%) harbored at least one ERBB2 mutation. The mutation rate was higher in patients with lobular histology (5.9%) compared to invasive breast carcinoma of no special type (2.6%). A total of 12 mutations were found with the following frequencies: L755S (25.00%), V777L (25.00%), S310Y (16.67%), L869R (16.67%), S310F (8.33%), and D769H (8.33%). Matched tumor samples from six patients identified the same mutations with an 83% concordance rate. In summary, our highly sensitive multiplex digital PCR assays are well suited for plasma-based monitoring of ERBB2 mutational status in patients with MBC.

Development of sensitive and robust multiplex digital PCR assays for the detection of ESR1 mutations in the plasma of metastatic breast cancer patients.

BACKGROUND: Early detection of ESR1 mutations is a key element for better personalization of the management of patients with HR+/HER2- Metastatic Breast Cancer (MBC). Analysis of circulating tumor DNA from liquid biopsies is a particularly well-suited strategy for longitudinal monitoring of such patients. MATERIALS AND METHODS: Using the naica® three-color digital PCR platform, we developed a screening assay allowing the detection of 11 ESR1 mutations and designed a sequential strategy for precise mutation identification. We then applied this strategy in the analysis of plasma circulating cell-free DNA from 109 HR+/HER2- MBC patients and performed a double-blind comparison study on a subset of patients with the multiplex assay used at the Institut Curie (IC) for the PADA-1 study. RESULTS: Thirty-one patients (28.4%) harboured at least one ESR1 mutation, with the following frequencies: D538G (41.03%), Y537S (25.64%), E380Q (10.26%), Y537N (10.26%), "(536-540)" (7.69%), Y537C (2.56%), and L536R (2.56%). The presence of ESR1 mutation(s) was significantly associated with liver metastases (p = 0.0091). A very good agreement (91%) was observed with the IC assay. CONCLUSION: Our assays have proven to be robust and highly sensitive and are very well-suited for monitoring ESR1 mutations in the plasma of MBC patients.

Development of multiplex digital PCR assays for the detection of PIK3CA mutations in the plasma of metastatic breast cancer patients.

With the approval of new therapies targeting the PI3K pathway, the detection of PIK3CA mutations has become a key factor in treatment management for HR+/HER2- metastatic breast cancer (MBC). We developed multiplex digital PCR (dPCR) assays to detect and quantify PIK3CA mutations. A first screening assay allows the detection of 21 mutations, with a drop-off system targeting the 542-546 hotspot mutations combined with the simultaneous detection of N345K, C420R, H1047L and H1047R mutations. In the case of a positive result, a sequential strategy based on other assays that we have developped allows for precise mutation identification. Clinical validity was determined by analyzing plasma circulating free DNA (cfDNA) from 213 HR+/HER2- MBC samples, as well as DNA extracted from 97 available matched tumors from 89 patients. Our assays have shown reliable specificity, accuracy and reproducibility, with limits of blank of three and four droplets for the screening assay. Sixty-eight patients (32%) had at least one PIK3CA mutation detectable in their plasma, and we obtained 83.1% agreement between the cfDNA analysis and the corresponding tumors. The high sensitivity and robustness of these new dPCR assays make them well-suited for rapid and cost-effective detection of PIK3CA mutations in the plasma of MBC patients.

Serum CD95L Level Correlates with Tumor Immune Infiltration and Is a Positive Prognostic Marker for Advanced High-Grade Serous Ovarian Cancer.

Soluble CD95L (s-CD95L) is a chemoattractant for certain lymphocyte subpopulations. We examined whether this ligand is a prognostic marker for high-grade serous ovarian cancer (HGSOC) and whether it is associated with accumulation of immune cells in the tumor. Serum s-CD95L levels in 51 patients with advanced ovarian cancer were tested by ELISA. IHC staining of CD3, CD4, CD8, CD20, CD163, CD31, FoxP3, CCR6, IL-17, Granzyme B, PD-L1, and membrane CD95L was used to assess tumor-infiltrating immune cells. Although the intensity of CD3, CD8, CD4, CD20, and CD163 in tumor tissues remained constant regardless of membrane CD95L expression, tumors in patients with HGSOC with s-CD95L levels ≥516 pg/mL showed increased infiltration by CD3+ T cells (P = 0.001), comprising both cytotoxic CD8+ (P = 0.01) and CD4+ (P = 0.0062) cells including FoxP3+ regulatory T cells (P = 0.0044). Also, the number of tumor-infiltrating CD20+ B cells (P = 0.0094) increased in these patients. Multivariate analyses revealed that low s-CD95L concentrations [<516 pg/mL, HR, 3.54; 95% confidence interval (CI), 1.13-11.11), and <1,200 activated CD8+ (Granzyme B+) cells (HR, 2.63; 95% CI, 1.16-5.95) were independent poor prognostic factors for recurrence, whereas >6,000 CD3+ cells (HR, 0.34; 95% CI, 0.15-0.79) was a good prognostic factor. Thus, low levels of s-CD95L (<516 pg/mL) are correlated with lower numbers of tumor-infiltrating lymphocytes (CD3+ and CD8+, and also CD4 and FoxP3 T cells) in advanced HGSOC and are a poor prognostic marker. IMPLICATIONS: Serum s-CD95L is correlated with a number of tumor-infiltrating immune cells in HGSOC and could be used as a noninvasive marker of tumor immune infiltration to select patients referred for immunotherapy trials that evaluate checkpoint inhibitor treatment.