CN114875151A

CN114875151A - Application of plasma exosome biomarker in screening or curative effect prediction of new auxiliary chemotherapy-sensitive population of gastric cancer

Info

Publication number: CN114875151A
Application number: CN202210676338.3A
Authority: CN
Inventors: 季加孚; 李子禹; 唐小欢; 郭婷; 高翔宇; 邢晓芳; 陕飞
Original assignee: Beijing Cancer Hospital
Current assignee: Beijing Cancer Hospital
Priority date: 2022-06-15
Filing date: 2022-06-15
Publication date: 2022-08-09
Anticipated expiration: 2042-06-15
Also published as: CN114875151B

Abstract

The invention relates to plasma exosome mRNA, miRNA and/or lncRNA biomarkers and application thereof in screening new auxiliary chemotherapy sensitive populations of gastric cancer patients, predicting new auxiliary chemotherapy curative effects and screening gastric cancer treatment medicines. The invention firstly determines that plasma exosomes mirnAlet-7i-5p, miR-1307-3p, miR-181a-5p and miR-1843, plasma exosomes mRNA LZIC and SRSF6 and plasma exosomes lncRNAncFTH 1-211 and lncPTMA-209 are key molecular characteristics in vivo of a gastric cancer patient in response to neoadjuvant chemotherapy. By using the biomarker and the combination thereof, the new auxiliary chemotherapy sensitive population of the gastric cancer patient can be effectively screened and the curative effect of the new auxiliary chemotherapy can be predicted only by a small amount of blood samples before treatment, and the realization of the optimal treatment strategy of the gastric cancer patient is greatly promoted.

Description

Application of plasma exosome biomarker in screening or curative effect prediction of new auxiliary chemotherapy-sensitive population of gastric cancer

Technical Field

The invention relates to the field of tumor molecular biology, in particular to a biomarker related to a new adjuvant therapy of gastric cancer and application thereof.

Background

About 42% of gastric cancers occur in our country globally, of which about 71% are Advanced Gastric Cancers (AGC). In recent years, the treatment mode of AGC gradually changes from single operation to multidisciplinary combination treatment mainly based on operation. Multiple studies have shown that for most of the later-staged AGC, the perioperative treatment modality can further improve patient survival compared to the standard radical surgery combined with post-operative adjuvant chemotherapy.

Neoadjuvant chemotherapy (NACT) is a general chemotherapy performed before surgery, and aims to reduce tumor size, reduce tumor staging, provide a drug sensitive result after surgery, and remove undetected micrometastases, so as to facilitate subsequent surgery and the like, and significantly improve the survival of patients with advanced gastric cancer. However, over half of the patients with gastric cancer had no significant tumor regression in the pathological foci after surgery, suggesting that this fraction of patients failed to benefit from NACT. Therefore, it is important to clinical practice to explore prediction of NACT efficacy and to screen patients sensitive to NACT.

At present, TNM staging and TRG staging are commonly used clinically to judge the response of a new adjuvant therapy population and therapy, however, the TNM standard cannot identify a sensitive population for therapy; TRG classification depends on post-operative pathology, and cannot be used for evaluating the curative effect before and during neoadjuvant therapy. Recent researches find that the molecular typing of tumors has a certain correlation with the chemotherapy curative effect of gastric cancer patients, such as TCGA and ACRG, wherein the tumors of MSI-H type in TCGA typing have poor curative effect on chemotherapy; tumor Mutational Burden (TMB) also has some suggestive effect. However, it remains to be verified whether treatment with clinically practical patients would benefit from the use of these molecular typing guidelines for treatment; moreover, the molecular spectrum analysis of enough samples obtained by multiple endoscopic biopsies not only has great damage to patients and high cost, but also is difficult to realize in clinic.

In addition, the markers are screened according to the survival of the patients in the past, and the survival of the patients is influenced by a plurality of factors and cannot directly respond to the pathological changes of the tumors caused by treatment. The treatment effect is more direct and reliable by evaluating the pathological reaction of the tumor, and related biomarkers are fewer at present, so that development of a more accurate and reliable exosome biomarker capable of screening new auxiliary chemotherapy sensitive people of the gastric cancer, predicting the new auxiliary chemotherapy curative effect of the gastric cancer or screening gastric cancer treatment drugs is urgently needed.

Disclosure of Invention

In order to solve the problems, the invention provides a biomarker capable of quickly and accurately screening the newly-assisted chemotherapy sensitive population of the gastric cancer patient and predicting the newly-assisted chemotherapy curative effect of the gastric cancer patient, and a composition, a reagent, a kit and application thereof. The technical scheme provided by the invention does not need in vivo biopsy, can realize non-invasive and real-time detection only by a small amount of blood, and has low cost and convenient use; has high AUC value, high sensitivity, high accuracy and high stability; the treatment effect is more direct and reliable by evaluating the pathological reaction of the tumor; can effectively screen the new auxiliary chemotherapy sensitive population of the gastric cancer patient, predict the new auxiliary chemotherapy curative effect of the gastric cancer patient or screen the drug for treating the gastric cancer.

Specifically, the invention provides a biomarker for screening a new auxiliary chemotherapy sensitive population of a gastric cancer patient, predicting the new auxiliary chemotherapy curative effect of the gastric cancer patient or screening a drug for treating the gastric cancer, wherein the biomarker comprises at least one of the following genes: let-7i-5p, miR-1307-3p, miR-181a-5p, miR-1843, LZIC, SRSF6, lncFTH1-211 and lncPTMA-209.

Further, the biomarker is an exosome biomarker;

further, the biomarker is a plasma exosome biomarker.

In another aspect, the present invention also provides a use of the biomarker of the present invention, wherein the biomarker is used for preparing a product for screening a population susceptible to neoadjuvant chemotherapy of a gastric cancer patient, or preparing a product for predicting the efficacy of neoadjuvant chemotherapy of a gastric cancer patient, or preparing a product for screening a gastric cancer treatment drug, and the biomarker comprises at least one of the following genes: let-7i-5p, miR-1307-3p, miR-181a-5p, miR-1843, LZIC, SRSF6, lncFTH1-211 and lncPTMA-209.

Further, the biomarkers include one, two, three, four, five, six, seven or eight thereof; preferably, the biomarkers include two, three or four thereof.

Further, the biomarkers include at least let-7i-5 p; preferably, the biomarkers include at least let-7i-5p and LZIC, let-7i-5p and miR-1307-3p, let-7i-5p and lncPTMA209, or let-7i-5p + lncFTH 1-211.

Further, the biomarkers are: let-7i-5p + lncFTH1-211, let-7i-5p + LZIC, let-7i-5p + lncPTMA209, let-7i-5p + miR-1307-3p + lncFTH1-211, miR-1843+ let-7i-5p + LZIC, let-7i-5p + miR-1307-3p + LZIC, miR-1843+ let-7i-5p + lncPTMA209, miR-181a-5p + let-7i-5p + LZIC, miR-181a-5p + let-7i-5p + lncPTMA209, miR-1843+ let-7i-5p + miR-1307-3p + LZIC or miR-181a-5p + let-7i-5p + miR-1307-3p + LZIC.

Further, the biomarker is an exosome biomarker; further, the biomarker is a plasma exosome biomarker.

Furthermore, the neoadjuvant chemotherapy refers to chemotherapy of fluorouracil antitumor drugs in combination with platinum antitumor drugs; preferably, the fluorouracil is 5-fluorouracil, capecitabine, tegafur, efonidine, carmofur or tegafur, and the platinum is cisplatin, carboplatin, nedaplatin, lobaplatin or oxaliplatin; further preferably, the neoadjuvant chemotherapy is an oxaliplatin-tegafur regimen or an oxaliplatin-capecitabine regimen.

Preferably, the product comprises oxaliplatin and tegafur, or capecitabine and capecitabine.

Further, gastric cancer refers to advanced gastric cancer.

Further, the product comprises reagents for detecting the expression level of a biomarker; preferably, the reagent comprises a fluorescent quantitative PCR reagent; further optionally, detection primers and/or probes are included.

Further, the product comprises an exosome-extracting agent; preferably, the product comprises a plasma exosome extracting agent; more preferably, the product comprises a plasma exosome RNA extraction reagent.

Further, the product is a reagent, a kit or a gene chip.

In another aspect, the present invention also provides a composition of biomarkers comprising two or more of the following genes: let-7i-5p, miR-1307-3p, miR-181a-5p, miR-1843, LZIC, SRSF6, lncFTH1-211 and lncPTMA-209.

Further, the combination of biomarkers includes two, three, four, five, six, seven or eight; preferably, the biomarkers include two, three or four.

Further, at least let-7i-5p and LZIC, let-7i-5p and miR-1307-3p, let-7i-5p and lncPTMA209 or let-7i-5p and lncFTH1-211 are included.

Further, the composition of the biomarkers is: let-7i-5p + lncFTH1-211, let-7i-5p + LZIC, let-7i-5p + lncPTMA209, let-7i-5p + miR-1307-3p + lncFTH1-211, miR-1843+ let-7i-5p + LZIC, let-7i-5p + miR-1307-3p + LZIC, miR-1843+ let-7i-5p + lncPTMA209, miR-181a-5p + let-7i-5p + LZIC, miR-181a-5p + let-7i-5p + lncPTMA209, miR-1843+ let-7i-5p + miR-1307-3p + LZIC or miR-181a-5p + let-7i-5p + miR-1307-3p + LZIC.

Furthermore, the biomarker is used for screening new auxiliary chemotherapy sensitive people of gastric cancer patients, predicting the new auxiliary chemotherapy curative effect of the gastric cancer patients or screening drugs for treating gastric cancer.

Further, the gastric cancer is advanced gastric cancer.

Further, the biomarker is an exosome biomarker.

Further, the biomarker is a plasma exosome biomarker.

In another aspect, the present invention also provides a reagent for detecting the expression level of the biomarkers and compositions thereof of the present invention in a biological sample.

Further, the reagent comprises a fluorescent quantitative PCR detection reagent; preferably, the detection reagent comprises a detection primer and/or a probe.

Further, the reagent further comprises an exosome-extracting reagent; preferably, a plasma exosome-extracting agent is comprised; further preferably, a plasma exosome RNA extraction reagent is included.

Furthermore, the reagent is used for screening new auxiliary chemotherapy sensitive people of gastric cancer patients, predicting the new auxiliary chemotherapy curative effect of the gastric cancer patients or screening gastric cancer treatment medicines.

In another aspect, the invention also provides a kit comprising the detection reagent of the invention.

Furthermore, the kit is used for screening the new auxiliary chemotherapy sensitive population of the gastric cancer patient, predicting the new auxiliary chemotherapy curative effect of the gastric cancer patient or screening the gastric cancer treatment medicine.

In another aspect, the present invention also provides a gene chip comprising probes for detecting the expression level of the biomarker or the composition of biomarkers of the present invention.

Furthermore, the gene chip is used for screening new auxiliary chemotherapy sensitive people of gastric cancer patients, predicting the new auxiliary chemotherapy curative effect of the gastric cancer patients or screening gastric cancer treatment medicines.

On the other hand, the invention also provides the application of the biomarker, the biomarker composition, the detection reagent, the detection kit or the gene chip in preparing products for screening new auxiliary chemotherapy-sensitive people of gastric cancer patients, products for predicting the new auxiliary chemotherapy curative effect of gastric cancer patients or products for screening drugs for treating gastric cancer.

Further, the gastric cancer is advanced gastric cancer.

Furthermore, the neoadjuvant chemotherapy refers to chemotherapy of fluorouracil antitumor drugs in combination with platinum antitumor drugs; preferably, the fluorouracil is 5-fluorouracil, capecitabine, tegafur, efonidine, carmofur or tegafur, and the platinum is cisplatin, carboplatin, nedaplatin, lobaplatin or oxaliplatin.

Further, the neoadjuvant chemotherapy is an oxaliplatin-tegafur regimen or an oxaliplatin-capecitabine regimen.

Further, the product also comprises an exosome extracting agent, preferably comprises a plasma exosome extracting agent, and further preferably comprises a plasma exosome RNA extracting agent.

Further, the primer and/or probe sequences in each of the foregoing aspects are selected from the following table:

on the other hand, the invention also provides a method for screening the new auxiliary chemotherapy sensitive population of the gastric cancer patient, which comprises the steps of extracting the plasma exosome RNA of the population to be detected, measuring the expression level of the biomarker or the composition thereof, and screening the sensitive population for the new auxiliary chemotherapy by analyzing the expression level.

On the other hand, the invention also provides a method for predicting the newly-assisted chemotherapy curative effect of a gastric cancer patient, which comprises the steps of extracting the plasma exosome RNA of the gastric cancer patient to be detected, measuring the expression level of the biomarker or the composition thereof in a biological sample, and predicting the treatment effect of the biomarker or the composition by analyzing the expression level.

On the other hand, the invention also provides a screening method of the gastric cancer treatment drug, the drug to be screened is added into gastric cancer cells, after the culture, the expression level of the biomarker or the composition thereof is measured, the expression level of the biomarker or the composition thereof in the gastric cancer cells before and after the drug is added is compared, and the drug with the changed expression level is the potential drug for treating gastric cancer.

Compared with the prior art, the invention at least obtains the following beneficial technical effects:

1. the invention discovers that plasma exosome biomarkers let-7i-5p, miR-1307-3p, miR-181a-5p, miR-1843, LZIC, SRSF6, lncFTH1-211 and lncPTMA-209 are key molecules of a gastric cancer patient in response to neoadjuvant chemotherapy for the first time, have high AUC value, high sensitivity, high accuracy and high stability, and can effectively screen a gastric cancer neoadjuvant chemotherapy sensitive population, predict the curative effect of the neoadjuvant therapy of the gastric cancer or screen drugs for treating the gastric cancer.

2. The invention is carried out by liquid biopsy, can realize non-invasive and real-time monitoring, and has low cost, convenient use and good stability. Only 1 ml of blood plasma is needed at each time, the injury to a patient is small, the risk of body injury of the patient caused by molecular typing identification of enough tumor tissues obtained by performing multiple times of tissue biopsy through a gastroscope is avoided, multiple times of sampling and evaluation accompanying treatment can be realized, the detection cost is greatly reduced, and the use is convenient.

3. Compared with RNA and protein molecules in plasma, the biomarker provided by the invention benefits from the protection of an exosome membrane structure, has more stable molecular expression level, higher sensitivity and specificity, and has important clinical application value.

4. By using the technical scheme of the invention, the screening of the stomach cancer neoadjuvant chemotherapy sensitive population and the prediction of the curative effect of the stomach cancer patient on the neoadjuvant chemotherapy can be realized only by a small amount of blood samples before the treatment starts, and the realization of the optimal treatment strategy of the stomach cancer patient is greatly promoted.

5. The invention evaluates the treatment effect by evaluating the pathological response of the tumor, and is more direct, reliable and effective compared with the prior screening marker based on the survival of the patient.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

FIG. 1: the technical scheme of the invention is a flow chart;

FIG. 2: exosome identification results (Western Blot, projection electron microscope, nano-tracing technology);

FIG. 3: performing differential analysis on TPM values of exosome RNA;

FIG. 4: panels a-C are the intersection of two sets of differential markers;

FIG. 5: training set and verification set AUC (AUC) graphs of the two-molecule model;

FIG. 6: three-component model training set and validation set AUC graph;

FIG. 7: and a four-subset model training set and a verification set AUC (AUC) graph.

Detailed Description

The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation. The overall process of the invention is illustrated in figure 1.

Example 1 screening of exosome RNAs associated with neoadjuvant chemotherapeutic efficacy

1. Inclusion objects

We randomly selected 10 healthy human volunteers and 20 patients with Advanced Gastric Cancer (AGC) as inclusion subjects. Healthy human volunteers were from the first hospital of Beijing university and gastric cancer patients were from the gastrointestinal tumor center, a ward of the tumor hospital of Beijing university. The proportion of both men and women is 9:1, and the proportion of both men and women is 90%; the average age was 57 years, with the age range 43-73 years. All 20 AGC patients received neoadjuvant chemotherapy with either SOX (oxaliplatin-tegafur) or XELOX (oxaliplatin-capecitabine) regimen (these two regimens are recommended by the chinese clinical oncology council (CSCO) guidelines (version 2021)), with the chemotherapy regimen: oxaliplatin (130 mg/m) ² ) Intravenously on the first day, tegafur (40-60 mg/m) ² ) Or capecitabine (1000 mg/m) ² ) The preparation is administered orally on day 1-14, and 3-5 treatment courses are administered every 3 weeks. Of the patients enrolled, 10 patients were of good efficacy and 10 patients were of poor efficacy.

The curative effects of the patients are distinguished according to the following judgment methods and standards: after the operation, 2 major physicians or more than the major physicians judge the curative effect according to the pathological condition of the excised specimens, the primary cancer focus is obviously retreated, and the curative effect is good without cancer cells or only scattered cancer cells; the cancer focus is not obviously withdrawn, and the treatment effect is poor without tumor cell necrosis or only with a small part of cancer cell necrosis.

2. Plasma collection:

before the patient receives the preoperative neoadjuvant chemotherapy, 2.0mL of peripheral blood of the patient is collected at 8-10 am in an empty stomach state, centrifuged for 10 minutes at 4 ℃ and 3000rpm, 1.0mL of blood plasma is extracted and stored in a refrigerator at-80 ℃. Plasma collection was performed by the same method by healthy persons after signing informed consent.

3. Exosome extraction:

after thawing the plasma was first filtered through 0.22um filter (EMD Millipore, Billerica, MA), the filtered plasma was applied to SEC exclusion column (Echobiotech, China) after washing with 10.0mL PBS, 10.0mL PBS was added, one fraction per 0.5mL, fractions 4-8 were collected, then concentrated to 50uL using 100kDa ultrafilter (Merck, Germany), exosome detection was performed using Western blot, transmission electron microscopy and nanotaper technology (fig. 2), and the extracted exosomes were quantitatively analyzed by BCA kit (Pierce Biotechnology, Rockford, CA).

4. Extracting exosome RNA:

total RNA was extracted from exosomes using miRNeasy plasma kit (Qiagen, cat.no. 217004).

5. Sequencing of exosomes mRNA, miRNA and lncRNA

We prepared the sequencing of total RNA from plasma-derived exosomes obtained from the above subjects. An exosome RNA expression library was constructed based on the smart strand Total RNA-Seq Kit V2(Takara Bio USA, Inc.) Kit assay and quantified by RNA unique molecular structure (UMI). The templates and corresponding reads are generated in the Illumina Hiseq platform. The TPM value corresponding to each of the RNAs was calculated by bioinformatics method (FIG. 3).

6. Differential analysis of exosome mrnas, mirnas and lncrnas

Differential analysis is carried out according to the TPM value of the exosome RNA, and the cell source is difficult to determine after the exosome is discharged outside the cell. Therefore, we first analyzed the exosome RNA expression difference between healthy and gastric cancer patients using the Mann-Whitney U test method, and screened exosome RNAs associated with gastric cancer. Later, we further analyzed the differentially expressed exosome RNAs of patients with good therapeutic effect and poor therapeutic effect, and we took the intersection of the two analyses as exosome RNAs related to the newly assisted chemotherapy of gastric cancer for subsequent analysis in order to eliminate the interference that may be generated by individual differences (fig. 4).

7. Screening of exosome RNA biomarkers related to neoadjuvant chemotherapy curative effect

The P value, the fold difference (FC) and the area under the operating curve (ROC) of a testee (AUC) of a gastric cancer patient with good neoadjuvant chemotherapy curative effect are screened by analyzing the mRNA, miRNA and lncRNA of exosomes, exosome RNAs with P less than 0.05, AUC more than 0.80 and the fold difference less than 0.67 or more than 1.50 are selected, and 31 exosome RNAs are screened out in total (Table 1).

TABLE 1 differential expression of exosome RNAs with area under the curve AUC exceeding 0.8.

Example 2 validation of exosome RNA biomarkers associated with neoadjuvant chemotherapy efficacy

To further verify the prediction efficacy of exosome RNAs, we comprehensively screened 18 exosome RNAs with high fold difference (specifically: 9 exosome mirnas (miR-27a-3p, miR-335-5p, miR-454-3p, miR-152-3p, miR-181a-5p, miR-1843, let-7i-5p, miR-130a-3p and miR-1307-3p), 5 exosome mrnas (LZIC, KMT2E, DAPP1, DAB2 and sf6) and 4 lncrnas (lncsta-209, lncrp-202, lncRPS24-210 and lncrth 1-211)), and verified in a new independent 43-stage gastric cancer patient cohort by real-time fluorescent quantitative PCR (qRT-PCR). The new 43 patients were also advanced gastric cancer patients and received a new adjuvant chemotherapy of SOX or XELOX regimen and D2 gastric cancer resection with 19 patients having good therapeutic effect and 24 patients having poor therapeutic effect. Wherein the treatment method, the therapeutic effect standard, the plasma collection method, the exosome, and the extraction method of exosome RNA of the analysis subject were the same as in example 1.

By PrimeScript ^TM The RT reagent Kit (Perfect Real Time) (TAKARA, RR037A) was used to perform qRT-PCR to determine the expression level of the above genes, and to further screen exosome RNAs with expression trends consistent and statistically significant differences from the candidate sequencing group shown in table 1. The primers and probes used are listed in Table 2 (where U6 and ENSG00000198804 are reference genes).

TABLE 2 Probe and primer sequences for RNA

By integrating AUC, expression trend consistency, statistical difference and difference multiple of exosome RNA in a training set and a verification set, 8 exosome RNAs (see Table 3) with better effect of predicting the treatment effect of the neoadjuvant chemotherapy are screened, wherein the exosome RNAs comprise 4 exosome miRNAs (let-7i-5p, miR-1307-3p, miR-181a-5p and miR-1843), 2 exosome mRNAs (LZIC and SRSF6) and 2 exosome lncRNAs (lncFTH1-211 and lncPTMA-209), the verification data of the exosome RNAs are consistent with the expression trend of the candidate sequencing group shown in Table 1, and the exosome RNAs have difference with statistical significance between patients with good treatment effect and patients with bad treatment effect.

Table 3 shows the results of single exosome RNA verification for neoadjuvant chemotherapy efficacy.

In addition, the expression levels of miR-335-5P, miR-454-3P, lncRMRP-202 and lncRPS24-210 are different between patients with good curative effect and poor curative effect in the verification set (P is less than 0.05), but the trend is opposite to that of the sequencing group, and no statistical difference exists after the two groups of data are combined; the expression levels of the other 6 exosome RNAs showed no significant difference between the validation set of patients with good and poor efficacy.

In conclusion, let-7i-5p, miR-1307-3p, miR-181a-5p, miR-1843, LZIC, SRSF6, lncFTH1-211 and lncPTMA-209 are exosome RNA molecules (Table 3) related to the curative effect of the gastric cancer neoadjuvant chemotherapy, the single-molecule AUC of the exosome RNA molecules is distributed in 0.723-0.812, the differentiation efficacy is high, the AUC is high in both training set and verification set, the stability is strong, and the exosome RNA molecules can be used for screening and curative effect prediction of clinical gastric cancer neoadjuvant chemotherapy sensitive people.

Example 3 construction and validation of exosome RNA model associated with neoadjuvant chemotherapy efficacy

To further explore better evaluation methods, we normalized the expression of 8 exosome RNAs (including 4 exosome miRNAs: let-7i-5p, miR-1307-3p, miR-181a-5p and miR-1843; 2 exosome mRNAs: LZIC and SRSF 6; and 2 exosome lncRNA: lncFTH1-211 and lncPTMA-209) in sequencing and validation groups of patients by the Z-score method, followed by the construction of a multi-index model from the existing data.

By applying a logistic regression method, firstly, a bipartite model group, a tripartite model group and a quartet model group are respectively constructed on the 8 exosomes, and it is found that in the three models, 3 bipartite models, 6 tripartite models and 2 quartet models are available, wherein the two bipartite models, the tripartite models and the quartet models are evaluated to have AUC (AUC) of a training set and a verification set of 0.80 respectively, and the AUC of the tripartite models and the quartet models are greater than 0.90 respectively in the training set and the verification set, so that the specificity, the sensitivity and the stability are high, and the models can effectively screen potential gastric cancer patients sensitive to new adjuvant chemotherapy and predict the curative effect of the new adjuvant chemotherapy. And the comparison shows that the AUC of the two-molecule model, the three-molecule model and the four-molecule model is further improved compared with that of the single-molecule model.

TABLE 4 model with AUC above 0.8 in training and validation set

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims

1. The application of the biomarker in preparing products for screening the new auxiliary chemotherapy-sensitive population of the gastric cancer patient is characterized in that the biomarker comprises at least one of the following genes: let-7i-5p, miR-1307-3p, miR-181a-5p, miR-1843, LZAC, SRSF6, lncFTH1-211 and lncPTMA-209.

2. The application of the biomarker in preparing products for predicting the treatment effect of neoadjuvant chemotherapy of gastric cancer patients is characterized in that the biomarker comprises at least one of the following genes: let-7i-5p, miR-1307-3p, miR-181a-5p, miR-1843, LZIC, SRSF6, lncFTH1-211 and lncPTMA-209.

3. The application of the biomarker in screening gastric cancer treatment drugs, wherein the biomarker comprises at least one of the following genes: let-7i-5p, miR-1307-3p, miR-181a-5p, miR-1843, LZIC, SRSF6, lncFTH1-211 and lncPTMA-20.

4. Use according to any one of claims 1 to 3, wherein:

the biomarkers comprise one, two, three, four, five, six, seven or eight of the biomarkers; preferably, the biomarkers include two, three or four thereof; further preferably, the biomarkers comprise at least let-7i-5 p; further preferably, the biomarkers comprise at least let-7i-5p and LZIC, let-7i-5p and miR-1307-3p, let-7i-5p and lncPTMA209 or let-7i-5p and lncFTH 1-211; more preferably, the biomarkers are: let-7i-5p + lncFTH1-211, let-7i-5p + LZIC, let-7i-5p + lncPTMA209, let-7i-5p + miR-1307-3p + lncFTH1-211, miR-1843+ let-7i-5p + LZIC, let-7i-5p + miR-1307-3p + LZIC, miR-1843+ let-7i-5p + lncPTMA209, miR-181a-5p + let-7i-5p + LZIC, miR-181a-5p + let-7i-5p + lncPTMA209, miR-1843+ let-7i-5p + miR-1307-3p + LZIC or miR-181a-5p + let-7i-5p + miR-1307-3p + LZIC;

and/or, the gastric cancer is advanced gastric cancer;

and/or, the biomarker is an exosome biomarker; preferably, the biomarker is a plasma exosome biomarker;

and/or the neoadjuvant chemotherapy refers to chemotherapy of fluorouracil antitumor drugs in combination with platinum antitumor drugs; preferably, the fluorouracil is 5-fluorouracil, capecitabine, tegafur, efonidine, carmofur or tegafur, and the platinum is cisplatin, carboplatin, nedaplatin, lobaplatin or oxaliplatin; further preferably, the neoadjuvant chemotherapy is an oxaliplatin-tegafur regimen or an oxaliplatin-capecitabine regimen;

and/or, the product comprises a reagent for detecting the expression level of the biomarker; preferably, the reagent comprises a fluorescent quantitative PCR detection reagent; further preferably, the reagents comprise detection primers and/or probes;

and/or, the product comprises an exosome-extracting agent; preferably, a plasma exosome extracting reagent is comprised; further preferably, the kit comprises a plasma exosome RNA extraction reagent;

and/or the product is a reagent, a kit or a gene chip.

5. A biomarker composition comprising two or more of the following genes: let-7i-5p, miR-1307-3p, miR-181a-5p, miR-1843, LZIC, SRSF6, lncFTH1-211 and lncPTMA-209.

6. The composition of claim 5, wherein:

the composition of biomarkers includes two, three, four, five, six, seven or eight of them, preferably, the biomarkers includes two, three or four of them; further preferably, the composition of the biomarkers comprises at least let-7i-5p and LZIC, let-7i-5p and miR-1307-3p, let-7i-5p and lncPTMA209 or let-7i-5p and lncFTH 1-211; further preferably, the composition of the biomarkers is: let-7i-5p + lncFTH1-211, let-7i-5p + LZIC, let-7i-5p + lncPTMA209, let-7i-5p + miR-1307-3p + lncFTH1-211, miR-1843+ let-7i-5p + LZIC, let-7i-5p + miR-1307-3p + LZIC, miR-1843+ let-7i-5p + lncPTMA209, miR-181a-5p + let-7i-5p + LZIC, miR-181a-5p + let-7i-5p + lncPTMA209, miR-1843+ let-7i-5p + miR-1307-3p + LZIC or miR-181a-5p + let-7i-5p + miR-1307-3p + LZIC;

and/or the composition of the biomarkers is used for screening the new auxiliary chemotherapy sensitive population of the gastric cancer patient, predicting the new auxiliary chemotherapy curative effect of the gastric cancer patient or screening the gastric cancer treatment medicine; preferably, the gastric cancer is advanced gastric cancer;

and/or, the biomarker is an exosome biomarker; preferably, the biomarker is a plasma exosome biomarker.

7. A test agent for detecting the expression level of the biomarker composition according to any one of claims 5 to 6.

8. The reagent of claim 7, wherein:

the reagent is used for screening new auxiliary chemotherapy sensitive population of gastric cancer patients, predicting new auxiliary chemotherapy curative effect of gastric cancer patients or screening gastric cancer treatment drugs;

and/or the reagent comprises a fluorescent quantitative PCR detection reagent; more preferably, the reagents comprise detection primers and/or probes;

and/or, the agent comprises an exosome-extracting agent; preferably, the kit comprises a plasma exosome extracting reagent, and further preferably comprises a plasma exosome RNA extracting reagent.

9. A test kit comprising the reagent of any one of claims 7-8; preferably, the kit is used for screening new auxiliary chemotherapy sensitive people of gastric cancer patients, predicting the new auxiliary chemotherapy curative effect of the gastric cancer patients or screening gastric cancer treatment medicines.

10. A gene chip comprising a probe for detecting the expression level of the biomarker composition according to any one of claims 5 to 6; preferably, the gene chip is used for screening new auxiliary chemotherapy sensitive people of gastric cancer patients, predicting the new auxiliary chemotherapy curative effect of the gastric cancer patients or screening gastric cancer treatment medicines.

11. Use of the biomarker composition according to any one of claims 5 to 6, the reagent according to any one of claims 7 to 8, the kit according to claim 9 or the gene chip according to claim 10 in the preparation of products for screening gastric cancer patients for neoadjuvant chemotherapy sensitivity, predicting the neoadjuvant chemotherapy curative effect of gastric cancer patients or screening gastric cancer treatment drugs.

12. The use of claim 11, wherein:

the gastric cancer is advanced gastric cancer;

and/or the neoadjuvant chemotherapy refers to chemotherapy of fluorouracil antitumor drugs in combination with platinum antitumor drugs; preferably, the fluorouracil is 5-fluorouracil, capecitabine, tegafur, efonidine, carmofur or tegafur, and the platinum is cisplatin, carboplatin, nedaplatin, lobaplatin or oxaliplatin; further preferably, the neoadjuvant chemotherapy is an oxaliplatin-tegafur regimen or an oxaliplatin-capecitabine regimen.

13. The use according to claim 4 or the reagent according to claim 8, wherein the primer and/or probe sequences are selected from the following table: