A CD19-BASED CHIMERIC ANTIGEN RECEPTOR AND APPLICATION THEREOF

Abstract

The present application provides a chimeric antigen receptor and application thereof. The chimeric antigen receptor comprises an antigen-binding domain, a transmembrane domain, a costimulatory signal transduction region, a CD3 signal transduction domain, and an inducible suicide fusion domain in tandem arrangement; wherein the antigen-binding domain binds to a tumor surface antigen and the tumor surface antigen is CD19.

Claims

1. A CD19-based chimeric antigen receptor comprising an antigen-binding domain, a transmembrane domain, a costimulatory signal transduction region, a CD3 signal transduction domain, and an inducible suicide fusion domain in tandem arrangement; wherein the antigen-binding domain binds to a tumor surface antigen, the antigen-binding domain is a single chain antibody against the tumor surface antigen CD19, the costimulatory signal transduction region comprises a CD27 signal transduction domain, and the inducible suicide fusion domain is iCasp9.

2. The chimeric antigen receptor according to claim 1, wherein the single-chain antibody against the tumor surface antigen CD19 has an amino acid sequence as shown in SEQ ID NO. 1 or an amino acid sequence having more than 90% homology thereto; the CD27 signal transduction domain has an amino acid sequence as shown in SEQ ID NO. 2; and the inducible suicide fusion domain iCasp9 has an amino acid sequence as shown in SEQ ID NO. 3.

3. The chimeric antigen receptor according to claim 2, wherein the inducible suicide fusion domain is connected in tandem with the CD3 signal transduction domain via a 2A sequence.

4. The chimeric antigen receptor according to any one of claims 1-3, wherein the transmembrane domain is a CD28 transmembrane domain and/or a CD8 transmembrane domain.

5. The chimeric antigen receptor according to claim 4, wherein the costimulatory signal transduction region further comprises a CD28 signal transduction domain.

6. The chimeric antigen receptor according to claim 1, wherein the chimeric antigen receptor comprises a signal peptide, an antigen-binding domain, a transmembrane domain, a costimulatory signal transduction domain, a CD3 signal transduction domain, a 2A sequence, and an inducible suicide fusion domain in tandem arrangement.

7. The chimeric antigen receptor according to claim 6, wherein the chimeric antigen receptor is a secretory signal peptide, a CD19 antigen-binding domain, a CD8 and/or CD28 transmembrane domain, a CD28 extracellular signal transduction domain, a CD28 intracellular signal transduction domain, a CD27 intracellular signal transduction domain, a CD3 intracellular signal transduction domain, a 2A sequence and a iCasp9 domain in tandem arrangement.

8. The chimeric antigen receptor according to claim 1, wherein the chimeric antigen receptor is secretory-CD19-CD28-CD27-CD3-2A-iCasp9; and the chimeric antigen receptor secretory-CD19-CD28-CD27-CD3-2A-iCasp9 has an amino acid sequence as shown in SEQ ID NO. 4 or an amino acid sequence having more than 80% homology thereto; or the chimeric antigen receptor Secretory-CD19-CD28-CD27-CD3-2A-iCasp9 has a nucleic acid sequence as shown in SEQ ID NO. 5 or a nucleic acid sequence having more than 80% homology thereto.

9. The chimeric antigen receptor according to claim 1, wherein the chimeric antigen receptor is transduced into T cells for expression by nucleic acid sequence encoding the same.

10. A recombinant lentivirus, which is obtained by co-transfection of mammalian cells with a viral vector comprising the chimeric antigen receptor according to claim 1 and packaging helper plasmids pNHP and pHEF-VSVG.

11. The recombinant lentivirus according to claim 10, wherein the mammalian cell is any one of a 293 cell, a 293T cell or a TE671.

12. A T cell comprising the chimeric antigen receptor according to claim 1.

13. A composition comprising any one of the chimeric antigen receptor according to claim 1.

14. (canceled)

15. The use according to claim 14, wherein the tumor is a blood-associated neoplastic disease; preferably, the blood-associated neoplastic disease is selected from leukemia or lymphoma.

16. The chimeric antigen receptor according to claim 9, wherein the transduction is performed via any one of a viral vector, a eukaryotic expression plasmid or an mRNA sequence, or a combination of at least two thereof, and transduced into T cells.

17. The chimeric antigen receptor according to claim 16, wherein the chimeric antigen receptor is transduced into T cells via a viral vector.

18. The chimeric antigen receptor according to claim 17, wherein the viral vector is any one of a lentiviral vector or a retroviral vector.

19. The chimeric antigen receptor according to claim 18, wherein the viral vector is a lentiviral vector.

20. A recombinant lentivirus, which is obtained by co-transfection of mammalian cells with a viral vector comprings the chimeric antigen receptor according to claim 1 and packaging helper plasmids pNHP and pHEF-VSVG.

21. A method for treating a tumor, comprising administrating a therapeutically effective amount of the chimeric antigen receptor according to claim 1 to a patient in need thereof.

22. The method according to claim 21, wherein the tumor is a blood-associated neoplastic disease.

23. The method according to claim 22, wherein the blood-associated neoplastic disease is selected from leukemia or lymphoma.

Description

DESCRIPTION OF THE DRAWINGS

[0047] FIG. 1 shows a synthetic gene sequence map of the chimeric antigen receptor of the present application;

[0048] FIG. 2 (a) are histograms showing the results of the flow cytometry analysis of primary B-ALL cells using a CD19 antibody, in which samples are obtained from the bone marrow of 3 B-ALL (B cell acute lymphoblastic leukemia) patients and the gray area represents negative control of the same type; FIG. 2 (b) are dot plots showing the results of the flow cytometry analysis of primary B-ALL cells stained with an CD19 antibody, in which samples are obtained from the bone marrow of 3 B-ALL patients;

[0049] FIG. 3 shows the results of in vitro CD19-specific killing test of leukemia cell lines by CAR-T cells;

[0050] FIG. 4(a) shows a dynamic comparison of the in vitro killing ability between CD19 CAR-T cells with different signal transduction domains; FIG. 4(b) shows a comparison of the ability between CD19 CAR-T cells with different signal transduction domains to release immune factors when killing in vitro;

[0051] FIG. 5 shows a flow chart of clinical trial using CD19 CAR-T cells;

[0052] FIG. 6 shows a comparison between the effects of the chimeric antigen receptor of the present application and of other chimeric antigens.

DETAILED DESCRIPTION

[0053] In order to further illustrate the technical measures adopted by the present invention and the effects thereof, the technical solutions of the present invention are further described below with reference to the accompanying drawings and specific embodiments, and however, the present invention is not limited to the scope of the embodiments.

[0054] In the examples, techniques or conditions, which are not specifically indicated, are performed according to techniques or conditions described in the literature of the art, or according to product instructions. The reagents or instruments for use, which are not indicated with manufacturers, are conventional products that are commercially available from many sources.

Example 1 Construction of Chimeric Antigen Receptors

[0055] (1) The Secretory signal peptide, CD19 antigen-binding domain, CD8 and/or CD28 transmembrane domain, CD28 signal transduction domain, CD27 signal transduction domain, CD3 signal transduction domain, 2A sequence and Caspase 9 domain, as shown in FIG. 1, i.e. Secretory-CD19-CD28-CD27-CD3-2A-iCasp9 was chemically synthesized by gene synthesis;

[0056] Example 2 Packaging of lentivirus

[0057] (1) 293T cells were used and cultured for 17-18 hours;

[0058] (2) Fresh DMEM containing 10% FBS was added;

[0059] (3) The following reagents were added to a sterile centrifuge tube: DMEM was taken for each well and helper DNA mix (pNHP, pHEF-VSV-G) and pTYF DNA vector were added, vortexed and shook;

[0060] (4) Superfect or any transgenic material was added to the centrifuge tube, left for 7-10 minutes at room temperature;

[0061] (5) To each culture cells the DNA-Superfect mixture in the centrifuge tube was added, vortexed and mixed;

[0062] (6) Cultured in a 3% CO.sub.2 incubator at 37 C. for 4-5 hours;

[0063] (7) The supernatant was drawn from the culture medium, the culture was rinsed with 293 cell media, and media was added for further culture;

[0064] (8) The culture was returned to the 5% CO.sub.2 incubator for overnight culture. The next morning and days later, transfection efficiency was observed with a fluorescence microscope if applicable.

Example 3 Purification and Concentration of Lentivirus

[0065] 1) Purification of Virus

[0066] Cell debris were removed by a centrifugation at 1000 g for 5 minutes to obtain virus supernatant. The virus supernatant was filtered with a 0.45 m low protein-binding filter, and the virus was divided into small portions and stored at 80 C.;

[0067] Typically, >10.sup.7 transducing units of lentiviral vector can be produced by transfected cells per ml of medium.

[0068] 2) Concentration of lentivirus with a Centricon filter

[0069] (1) The virus supernatant was added to the Centricon filter tube, then centrifuged at 2500 g for 30 minutes;

[0070] (2) The filter tube was shaken, then centrifuged at 400 g for 2 minutes, and the concentrated virus was collected to a collection cup. Finally, the virus was collected from all tubes into a single centrifuge tube.

Example 4 Transduction of CAR-T Cells

[0071] The activated T cells were seeded into a culture dish, and the concentrated lentivirus with specificity to target antigens was added, centrifuged at a rate of 100 g of centrifugal force for 100 minutes (spinoculation), then cultured at 37 C. for 24 hours, and AIM-V media containing cell culture factors were added, after 2-3 days of culture, the cells were harvested and counted to give available CD19 CAR-T cells.

Example 5 Killing of Leukemia Cell Lines by CAR-T Cells In Vitro

[0072] (1) It can be seen from Figures. 2 (a) and 2 (b) that CD19 was highly expressed on the surface of primary bone marrow B-ALL cells and was widely expressed in patients with B-ALL, indicating that the CD19 chimeric antigen receptor selected for use in the present application can be used to treat B-ALL.

[0073] (2) In vitro evaluation of recognition and killing effects of CAR-T cells on target cells: non-specific T cells, GD2 CAR-T cells and specific 4S-CD19 CART (4S-CAR19) cells prepared in the present application were co-cultured with target cells expressing CD19 rather than GD2, i.e. RS4-11 (human acute lymphoblastic leukemia cell line) expressing GFP (T cells: RS4-11=3:1), in a 5% CO.sub.2 incubator at 37 C. for 24 h;

[0074] (3) After the co-culture at different time points, cells were stained with Annexin V and PI and analyzed by flow cytometry. Wherein, AnnexinV positive cells were cells on the verge of apoptosis (early apoptosis) as a result of specific killing, AnnexinV and PI double positive cells were apoptotic cells as a result of specific killing, and PI positive cells were generally dead cells.

[0075] The results were shown in FIG. 3. It can be seen from the flow cytometry graph showing GFP fluorescence intensity that cells with a fluorescence intensity of 10.sup.3 or more were target RS4-11 tumor cells (GFP labeled), thus were gated for further analysis. When RS4-11 cells were co-cultured with no T cells, it was shown in the background that 9% of target cells were on the verge of apoptosis and 6% of target cells were apoptotic. When RS4-11 cells were co-cultured with unmodified general T cells, 18.0% of target cells were on the verge of apoptosis and 26.4% of target cells were apoptotic, which was taken as a non-specific killing background value. When RS4-11 cells were co-cultured with GD2 CAR-T cells, 17.3% of target cells were on the verge of apoptosis, and 29.9% of target cells were apoptotic, which was also taken as a non-specific killing background value. When RS4-11 cells were co-cultured with specific CD19 CAR-T cells, 22.3% of target cells were on the verge of apoptosis, and 52.8% of target cells were apoptotic, which was the effect of specific killing. It was shown that the numbers of target cells on the verge of apoptosis and of apoptotic target cells were significantly higher for T cells with a CD19 chimeric antigen receptor than other control groups, therefore the CD19 chimeric antigen receptor had an increased killing effect on target RS4-11 cells.

Example 6 Dynamic Comparison of In Vitro Killing by CD19 CAR-T Cells and Safety Test

[0076] (1) Non-specific T cells or CD19 CAR-T cells comprising different signal transduction domains, including 41BB CAR19, 28-27 CAR19 and the 28-27 Caspase9 CAR19 (4S-CAR19) of the present application were co-cultured with RS4-11 in a 5% CO.sub.2 incubator at 37 C. for 24 h. The percentage of alive RS4-11 cells was recorded at 2 hours, 6 hours, and 24 hours after the culture, and the results were shown in FIG. 4(a). The 41BB CAR19, 28-27 CAR19, and 28-27 Caspase9 CAR19 of the present application had significant killing effects on RS4-11 cells compared to T cells of the control group. As can be seen from the data obtained at 2 hours and 6 hours after the culture, the 28-27 Caspase9 CAR19 of the present application had a relatively slow killing dynamics, at 24 hours after the culture; however, a same killing effect as 41BB CAR19 and 28-27 CAR19 was achieved. It was shown that the leukemia cell ablation caused by the 28-27 Caspase9 CAR19 of the present application does not induce a severe toxicity response (cytokine release syndrome, CRS) in clinical application.

[0077] (2) Non-specific T cells or CD19 CAR-T cells comprising different signal transduction domains, including 41BB CAR19, 28-27 CAR19 and the 28-27 Caspase9 CAR19 of the present application were co-cultured with RS4-11 in a 5% CO.sub.2 incubator at 37 C. After 6 h, the amount of immune factors produced by different CD19 CAR-T cells and degranulation effects were detected by an intracellular factor staining method, and the results were shown in FIG. 4(b). The 41BB CAR19, 28-27 CAR19, and the 28-27 Caspase9 CAR19 of the present application showed stronger (CD107a) degranulation ability and more interferon and interleukin-2 were produced compared to T cells of the control group. With regard to the percentage of cells producing interferon, it was 0.6% for T cells of the control group, 6.9% for the 41BB CAR19, 4.3% for the 28-27 Caspase9 CAR19, and 6.3% for the 28-27 CAR19. With regard to the percentage of cells producing interleukin-2, it was 2.5% for T cells of the control group, 8.9% for the 41BB CAR19, 8.8% for the 28-27 Caspase9 CAR19, and 10.2% for the 28-27 CAR19. It can be seen that after 6 hours of co-culture, the 28-27 Caspase9 CAR19 of the present application released lower amount of immune factors than CD19 CAR-T cells with other types of signal transduction domains. It can be inferred that the 28-27 Caspase9 CAR19 (4SCAR19) of the present application does not cause a severe immune factor storm (CRS) when used in clinical application, which enhances the safety of the therapy.

Example 7 Clinical Application of CAR-T Cells

[0078] The laboratory worked in cooperation with 22 clinical medical centers and hospitals from July 2013 to July 2016, and treated and closely followed 102 of CD19-positive and chemotherapy-tolerant B-ALL patients who met the enrollment criteria. There were a total of 55 children and 47 adults, 27 of which had undergone allogeneic hematopoietic stem cell transplantation. The patients had a median percentage of early leukemia cell blasts in bone marrow of 14.5% (ranging from 0% to 98%) at the time of receiving CAR-Ts. Among those patients, 69 patients had less than 50% of early leukemia blasts in bone marrow, and the other 33 patients had more than 50% of leukemia blasts in bone marrow. The median time period from initial diagnosis to CAR-T cell therapy was 17 months (range from 2 to 164 months).

[0079] The flow chart of the clinical trial was shown in FIG. 5. The patients was first evaluated by the hospitals and the laboratory, and the autologous or donor white blood cells were collected if the enrollment conditions were met. Then following the standard protocol, CD3-positive T cells were screened from PBMC, activated and transfected with 4SCAR19 to prepare CD19 CAR-T cells. The patients were pretreated with cyclophosphamide and/or fludarabine prior to infusion. The average number of cells to be infused was 1.0510.sup.6 cells per kilogram of body weight. The quality of white blood cells and CAR-T cells, the gene transfection rate, the expansion of CAR-T cells and the effective number of infused CAR-T cells were evaluated and recorded. After the infusion of CAR-T cells into patients, the immune factor storm and CAR copy number were closely monitored within one month. The conclusion of treatment toxicity and final treatment outcomes are obtained by long-term of clinical and laboratory evaluations. Toxicity evaluation was performed based on the National Cancer Institute's Common Terminology Criteria for Adverse Events (CTCAE v4.03). The COX proportional hazard model was used to analyze the category variables and continuous variables, and the Kaplan-Meier curve was used for survival analysis. The results were shown in Tables 1-3.

TABLE-US-00008 Total Patients Children Adults Early Response Complete Remission (CR) 96 (87%) 51 (88%) 45 (87%) No Remission (NR) 14 (13%) 7 (12%) 7 (13%) RFS, days Median 115.5 113.5 116.5 Range 0-455 0-450 0-455 OS, days Median 222 250 207.5 Range 23-1041 30-1041 23-1003

[0080] There were a total of 110 patients who received CD19 CAR-T cell therapy in four years, from whom complete data were collected. Complete remission was achieved in 96 patients, including 51 children and 45 adults. The average number of days without recurrence exceeded 100 days, and the overall survival days exceeded 200 days. The results showed a good therapeutic effect of the 4SCAR19 T cells of the present application.

TABLE-US-00009 Malignant cells Malignant cells Total in bone in bone Patients marrow <50% marrow >=50% Immune Grade 0-2 97 (88%) 67 (93%) 30 (79%) factor storm Grade 3-4 13 (12%) 5 (7%) 8 (21%)

[0081] Among the patients with bone marrow malignant cells less than 50%, there were 55 patients who only had a Grade 0-1 immune factor storm response, and 17 patients had a Grade 2-4 response. Among patients with bone marrow malignant cells greater than or equal to 50%, there were 17 patients who had a Grade 0-1 grade immune factor storm response, and 21 patients had a Grade 2-4 grade response. Overall, 65% of patients only had a Grade 0-1 immune factor storm response, and there was no statistical correlation between the intensity of the response and the malignant cell load before the re-infusion. These results demonstrated the safety of the CD19 CAR-T cells of the present application.

[0082] Table 3 shows the expansion of CAR-T cells in vivo.

TABLE-US-00010 CAR copy number in peripheral Total blood after the re-infusion patients 0% 1 (1%) >0%~1% 60 (55%) >1%~5% 32 (29%) >5% 8 (7%)

[0083] The number of CAR copies was detectable in peripheral blood within three weeks after the infusion of CAR-T cells into patients. Among the 101 patients whom have been collected data with, there was only one patient who had no detected copy number, and there were another 60 patients who had a detected copy number below 1%, 32 patients had a copy number from 1% to 5%, and still 8 patients had a detected copy number more than 5%. Due to the large number of peripheral blood cell bases, the detection of 1% of CAR copy number represented a significant amplification of CAR-T cells. It can be known from this table that the CD19 CAR-T cells of the present application were well expanded in vivo, and can well perform the function to kill cancer cells.

[0084] In summary, the single-chain antibody of the chimeric antigen receptor of the present application against the CD19 tumor surface antigen is not prone to mutation escape. It can be seen from FIG. 6 that the chimeric antigen receptor of the present application had a better effect than other chimeric antigen receptors. Through optimization and modification of the T cell signal transduction region, the chimeric antigen receptor of the present application is allowed to have a better killing effect and does not induce a severe immune factor storm (CRS), and is accompanied with a safety designed removal mechanism, so that the immune effect of the CAR-T cells is enhanced, with increased therapeutic and safety effect of the CAR T cells.

[0085] The Applicant declares that detailed methods of the present application have been described through the above examples, and however, the present application is not limited to the above detailed methods. That is to say, it does not mean that the implementation of the present application must rely on the above detailed methods. Those skilled in the art should understand that any improvement on the present application, including the equivalent replacement of the raw materials or the addition of auxiliary components to the product of the present application, and the selection of specific methods, etc., falls within the protection scope and the disclosure scope of the present application.