Unique genetic profiles from cerebrospinal fluid cell-free DNA in leptomeningeal metastases of EGFR-mutant non-small-cell lung cancer: a new medium of liquid biopsy

Background

Leptomeningeal metastases (LM) are more frequent in non-small-cell lung cancer (NSCLC) with epidermal growth factor receptor (EGFR) mutations. Due to limited access to leptomeningeal lesions, the purpose of this study was to explore the potential role of cerebrospinal fluid (CSF) as a source of liquid biopsy in patients with LM.

Patients and methods

Primary tumor, CSF, and plasma in NSCLC with LM were tested by next-generation sequencing. In total, 45 patients with suspected LM underwent lumbar puncture, and those with EGFR mutations diagnosed with LM were enrolled.

Results

A total of 28 patients were enrolled in this cohort; CSF and plasma were available in 26 patients, respectively. Driver genes were detected in 100% (26/26), 84.6% (22/26), and 73.1% (19/26) of samples comprising CSF cell-free DNA (cfDNA), CSF precipitates, and plasma, respectively; 92.3% (24/26) of patients had much higher allele fractions in CSF cfDNA than the other two media. Unique genetic profiles were captured in CSF cfDNA compared with those in plasma and primary tissue. Multiple copy number variations (CNVs) were mainly identified in CSF cfDNA, and MET copy number gain identified in 47.8% (11/23) of patients was the most frequent one, while other CNVs included ERBB2, KRAS, ALK, and MYC. Moreover, loss of heterozygosity (LOH) of TP53 was identified in 73.1% (19/26) CSF cfDNA, which was much higher than that in plasma (2/26, 7.7%; P < 0.001). There was a trend towards a higher frequency of concomitant resistance mutations in patients with TP53 LOH than those without (70.6% versus 33.3%; P = 0.162). EGFR T790M was identified in CSF cfDNA of 30.4% (7/23) of patients who experienced TKI progression.

Conclusion

CSF cfDNA could reveal the unique genetic profiles of LM and should be considered as the most representative liquid biopsy medium for LM in EGFR-mutant NSCLC.

Global gene expression profiling of PAX-FKHR fusion-positive alveolar and PAX-FKHR fusion-negative embryonal rhabdomyosarcomas

Paediatric rhabdomyosarcomas (RMS) are classified into two major subtypes based on histological appearance, embryonal (ERMS) and alveolar (ARMS), but this clinically critical distinction is often difficult on morphological grounds alone. ARMS, the more aggressive subtype, is associated in most cases with unique recurrent translocations fusing the PAX3 or PAX7 transcription factor genes to FKHR. In contrast, ERMS lacks unique genetic alterations. To identify novel diagnostic markers and potential therapeutic targets, we analysed the global gene expression profiles of these two RMS subtypes in 23 ARMS (16 PAX3-FKHR, 7 PAX7-FKHR) and 15 ERMS (all PAX-FKHR-negative) using Affymetrix HG-U133A oligonucleotide arrays. A statistically stringent supervised comparison of the ARMS and ERMS expression profiles revealed 121 genes that were significantly differentially expressed, of which 112 were higher in ARMS, including genes of interest as potential diagnostic markers or therapeutic targets, such as CNR1, PIPOX (sarcosine oxidase), and TFAPbeta. Interestingly, many known or putative downstream targets of PAX3-FKHR were highly overexpressed in ARMS relative to ERMS, including CNR1, DCX, ABAT, ASS, JAKMIP2, DKFZp762M127, and NRCAM. We validated the highly differential expression of five genes, including CNR1, DKFZp762M127, DCX, PIPOX, and FOXF1 in ARMS relative to ERMS by quantitative RT-PCR on an independent set of samples. Finally, we developed a ten-gene microarray-based predictor that distinguished ARMS from ERMS with approximately 95% accuracy both in our data by cross-validation and in an independent validation using a published dataset of 26 samples. The gene expression signature of ARMS provides a source of potential diagnostic markers, therapeutic targets, and PAX-FKHR downstream genes, and can be used to reliably distinguish these sarcomas from ERMS.

p53, epidermal growth factor, and platelet-derived growth factor in uterine leiomyosarcoma and leiomyomas

Uterine leiomyosarcoma (ULMS) is an aggressive gynecological disease. Although ULMS are often found in association with benign leiomyoma (LMA), little is known regarding the relationship between these benign and malignant smooth muscle neoplasms. The objective of this study was to evaluate the expression of epidermal growth factor (EGFR), platelet-derived growth factor (PDGFR), and p53 in ULMS specimens, their prognostic relevance, and the expression of these molecular markers when compared to benign LMA specimens. Between 1991 and 2001, 25 patients were identified with high-grade primary ULMS and for whom tissue was available. Tissue microarray was created with three representative cores from each of the ULMS cases as well as from 19 patients with benign uterine leiomyomata. Immunohistochemical (IHC) staining was performed for EGFR, PDGFR, and p53. Negative and positive IHC staining was scored for each marker. Outcome analysis was performed only for ULMS. Survival was determined from the time of initial diagnosis to last follow-up. Twelve (48%) ULMS expressed p53 compared to none of the LMA (P < 0.001), and 15 (60%) ULMS cases showed PDGFR expression compared to 32% of LMA samples (P= 0.08). EGFR expression did not differ between ULMS and LMA groups. ULMS patients with p53 expression had a poorer survival compared to ULMS patients with negative expression (P= 0.07). ULMS tumor stage had the strongest association with overall survival (P= 0.05). Our study supports previous investigations indicating that p53 expression may serve as a prognostic marker for ULMS patients. The difference in PDGFR expression between ULMS and LMA demonstrated a trend toward significance. EGFR was not commonly expressed in ULMS. These uniquely expressed markers may assist in stratifying patients by survival and identify novel therapeutic markers. Clearly, further investigation is needed.

Topotecan and liposomal doxorubicin in recurrent ovarian cancer: is sequence important?

A variety of agents have emerged to treat patients with recurrent epithelial ovarian cancer (EOC). Most patients receive both topotecan (T) and liposomal doxorubicin (D); however, there are no data regarding the benefit of a sequence-D followed by T (DT) or T followed by D (TD). We identified 89 consecutive patients with recurrent EOC, who received both D and T from January 1994 to January 2004 at Memorial Hospital. We compared the duration of treatment, toxicity, and overall survival (OS) for patients who received either DT or TD. Sixty-four patients received DT, and 25 patients received TD. The groups were balanced regarding age, stage, surgical debulking, platinum sensitivity, prior therapy, and intervening drugs between D and T. Median numbers of cycles on DT and TD were seven and six, respectively (P= 0.61); there was no difference in duration based on platinum sensitivity. Removal from therapy for toxicity was similar, DT (22%) and TD (36%) (P= 0.18). Finally, there was no difference in median OS based on sequence, DT (18.28 months) and TD (17.75 months) (P= NS). Platinum sensitivity did not affect median OS based on sequence. Based on duration, toxicity, and OS there is no advantage of one sequence of D and T when treating patients with recurrent EOC.

Topotecan and liposomal doxorubicin in recurrent ovarian cancer: is sequence important?

A variety of agents have emerged to treat patients with recurrent epithelial ovarian cancer (EOC). Most patients receive both topotecan (T) and liposomal doxorubicin (D); however, there are no data regarding the benefit of a sequence—D followed by T (DT) or T followed by D (TD). We identified 89 consecutive patients with recurrent EOC, who received both D and T from January 1994 to January 2004 at Memorial Hospital. We compared the duration of treatment, toxicity, and overall survival (OS) for patients who received either DT or TD. Sixty-four patients received DT, and 25 patients received TD. The groups were balanced regarding age, stage, surgical debulking, platinum sensitivity, prior therapy, and intervening drugs between D and T. Median numbers of cycles on DT and TD were seven and six, respectively (P= 0.61); there was no difference in duration based on platinum sensitivity. Removal from therapy for toxicity was similar, DT (22%) and TD (36%) (P= 0.18). Finally, there was no difference in median OS based on sequence, DT (18.28 months) and TD (17.75 months) (P= NS). Platinum sensitivity did not affect median OS based on sequence. Based on duration, toxicity, and OS there is no advantage of one sequence of D and T when treating patients with recurrent EOC.