DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
1. Claim 2 has been cancelled.
Claims 1 and 3-20 are pending and under examination.
Claim Rejections - 35 USC § 103
2. In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
3. Claims 1, 3-14, 19, and 20 are rejected under 35 U.S.C. 103 as being unpatentable over Cortin et al. (Biotechnol. Prog., 2004, 20: 858-863), in view of all
Smith et al. (BioProcess International, 2015, 13: 20-28), Whitford et al. (Genetic Engineering & Biotechnology News, 2015), Petiot et al. (BMC Biotechnol., 2011, 11: 1-12), and Clinke et al. (Biotechnol. Prog., 2013, 29: 754-767).
Cortin et al. teach culturing and expanding a suspension of uninfected HEK293S cells in a bioreactor using a tangential flow perfusion hollow fiber device, where tangential flow perfusion culturing maintains 100% viability after 10 days in culture and where tangential flow perfusion culturing increases volumetric production (claims 1, 3, 7-13) (see Abstract; p. 858-860; p. 862, column 2, second and third paragraphs).
With respect to claim 4, Cortin et al. do not specifically disclose a comparison with fed-batch culture. However, Cortin et al. teach 100% viability after 10 days in culture and thus, such a comparison is not significant because it does not provide a novel feature over Cortin et al.
With respect to claim 9, the hollow fiber device is a cell retention device (i.e., the bioreactor is connected to a cell retention device), as also defined by the specification (see [0035]).
Cortin et al. do not teach producing exosomes (claims 1 and 20). Smith et al. teach that exosomes, naturally secreted by cells, have therapeutic potential. Smith et al. teach that cell manufacturers produce exosome which accumulate in the conditioned medium and are simply discarded as waste, losing a potentially valuable therapeutic resource (see Abstract). Whitford et al. teach that bioreactors were used in the prior art for efficient and scalable exosome production (see p. 20, column 1, first paragraph; p. 22, column 3 and Fig. 2; p. 24, paragraph bridging columns 2 and 3; p. 26). Cortin et al. teach that tangential flow perfusion culturing results in enhanced cell numbers at high densities as compared to the other culturing methods, which leads to increased volumetric production (see p. 860, column 2; p. 862, column 2, third paragraph).
Based on these teachings, one of skill in the art would have known that the conditioned medium collected from the bioreactor of Cortin et al. is a source of high exosome numbers produced by the uninfected HEK293S cells. One of skill in the art would have found obvious to modify Cortin et al. by collecting this conditioned medium and further harvesting the exosomes to achieve the predictable result of obtaining enhanced exosomes yields (claim 1).
The exosomal preparation taught by the combined cited prior art necessarily exhibits the characteristics recited in claims 5 and 6 because all that is required to achieve such is to use the perfusion culturing method of Cortin et al. The specification does not teach more than this (see [0066]; [00105]; [00108]).
Cortin et al., Smith et al., and Whitford et al. do not teach a chemically defined medium (claim 1), nor do they teach HEK293 SF cells (claim 14). However, Smith et al. teach the need of using serum-free media when preparing exosomes (see p. 24, column 3). Whitford et al. suggest using serum-free media to obtain exosomes free of the contaminating exosomes present in serum (see p. 1, column 3). Furthermore, using chemically defined media (i.e., lacking serum and animal components) to cultivate HEK293 cells was practiced in the prior art. For example, Petiot et al. teach cultivating HEK293 SF cells adapted to growth in chemically defined media (see p. 2, column 2, first two paragraphs; p. 9, column 1, last paragraph). Modifying Cortin et al. by using HEK293 SF and a chemically defined medium would have been obvious to one of skill in the art to achieve the predictable result of obtaining contaminant-free exosomes.
With respect to the volumetric production (claim 1), Whitford et al. teach that hollow fiber bioreactors could achieve a volumetric production of 1.1x1012 exosomes/ml/14 days (i.e., about 7.9x1010 exosomes/ml/day; see p. 2). Thus, one of skill in the art would have reasonably expected to achieve a volumetric production of at least 7.9x1010 exosomes/ml/day. With respect to the volumetric production being at least 1x1011 exosomes/ml/day (claim 1), since Whitford et al. teach that hollow fiber bioreactors achieve high-density culture and also that the bioreactors are scalable to even higher production (see p. 2, Table 2), one of skill in the art would have found obvious to use routine experimentation and vary the density and/or size of the bioreactor to achieve the predictable result of obtaining enhanced exosome volumetric production.
Cortin et al., Smith et al., Whitford et al., and Petiot et al. do not teach growing the cells to a desired cell density and bleeding to maintain the target cell density (claim 1). However, doing so is suggested by the prior art. For example, while Cortin et al. disclose achieving a viable cell density (VCD) of 14.4 x 106 cell/ml, Cortin et al. also teach that the perfusion culture was still in the growth phase and could probably have attained higher concentrations (see p. 860, column 2, first full paragraph). Clinke et al. teach that high cell densities (such between 30 x 106 and 1.3 x 108cells/ml) could be achieved when using tangential flow perfusion and that these high densities could be maintained by cell bleeds (see Abstract). Based on these teachings, one of skill in the art would have found obvious to attain a desired high cell density and use cell bleeds to maintain the desired cell density with the reasonable expectation that doing so would result in high exosome yields.
With respect to the claimed range of 300-400 ml/min, it is noted that there is no evidence of record indicating that the selection of this range was other than routine or that the results should be considered unexpected in any way as compared to the closest prior art (see MPEP 2144.05 II). Clinke et al. teach that, for high cell densities, higher flow rates in the recirculation loop prevent hollow fiber fouling; maintaining a high cell density and a flow rate of 300 or 700 ml/min in the recirculation loop allows using a single hollow fiber for a prolonged time, without requiring a washing line (see p. 755, column 2, second full paragraph; paragraph bridging p. 763 and 764; paragraph bridging p. 765 and 766). Based on these teachings, one of skill in the art would have reasonable concluded that flow rates between 300 and 700 ml/min could be used once the desired cell density was reached and that such flow rates would reduce hollow fiber fouling, thus maintaining high exosome production. One of skill in the art would have also found obvious to use routine experimentation and vary the flow rate in the recirculation loop between 300 and 700 ml/min, with the reasonable expectation that doing so would identify the flow rate necessary to maintain high exosome production.
Thus, the claimed invention was prima facie obvious at the time of its effective filing date.
4. Claims 1, 3-14, 19, and 20 are rejected under 35 U.S.C. 103 as being unpatentable over Cortin et al. taken with all Smith et al., Whitford et al., Petiot et al., and Clinke et al., in further view of Ohno et al. (Mol. Ther., 2013, 21: 185-191).
The teachings of Cortin et al., Smith et al., Whitford et al., Petiot et al., and Clinke et al. are applied as above for claims 1, 3-14, 19, and 20. Cortin et al., Smith et al., Whitford et al., Petiot et al., and Clinke et al. do not teach exosomes comprising a therapeutic agent (claim 19). Ohno et al. teach preparing GE11 and EGF-positive exosomes secreted from HEK293 cells genetically engineered with an expression vector encoding the GE11 peptide or EGF, where the exosomes could be used to deliver therapeutic let-7a miRNA to EGFR-expressing cancer cells (see Abstract; p. 185, column 2, third full paragraph; paragraph bridging p. 185 and 186; p. 187, paragraph bridging columns 1 and 2; paragraph bridging p. 187 and 188; p. 189, column 2, third full paragraph; p. 190, column 1, second to last paragraph). Modifying the method of Cortin et al. Smith et al., Whitford et al., Petiot et al., and Clinke et al. by
genetically engineered the HEK293SF cells to express GE11 peptide or EGF would have been obvious to one of skill in the art to achieve predictable result of obtaining enhanced yields of genetically engineered therapeutic exosomes.
Thus, the claimed invention was prima facie obvious at the time of its effective filing date.
5. Claims 1, 3-17, 19, and 20 are rejected under 35 U.S.C. 103 as being unpatentable over Cortin et al. taken with all Smith et al., Whitford et al., Petiot et al., and Clinke et al., in further view of both Yim et al. (Nature Communications, July 2016, 7: 1-9) and Stipp et al. (J. Biol. Chem., 2001, 276: 4853-4862), as evidenced by UniProtKB.
The teachings of Cortin et al., Smith et al., Whitford et al., Petiot et al., and Clinke et al. are applied as above for claims 1, 3-14, 19, and 20. Cortin et al., Smith et al., Whitford et al., Petiot et al., and Clinke et al. do not teach exosomes overexpressing PTGFRN (claims 15-17). Yim et al. teach efficiently loading exosomes with a protein by transfecting HEK293 cells with plasmids encoding a fusion between the protein and the exosome-associated tetraspanin CD9 or CD81; the exosomes are useful for the intracellular delivery of proteins of interest in vitro and in vivo; the protein of interest could be the pro-apoptotic protein Bax (see Abstract; p. 2, column 1, third paragraph and paragraph bridging columns 1 and 2; p. 4, paragraph bridging columns 1 and 2; paragraph bridging p. 7 and 8). While Yim et al. does not teach PTGFRN, Stipp et al. teach that FPRP is a highly specific CD9- and CD81-associated transmembrane protein, wherein essentially 100% of cell surface FPRP on HEK293 cells is associated with CD9 and CD81 (see Abstract). Based on these teachings, one of skill in the art would have found obvious to modify the teachings of Cortin et al., Smith et al., Whitford et al. Petiot et al., and Clinke et al. by further overexpressing a fusion between FPRP and a protein of interest (such as Bax) to achieve the predictable result of obtaining a composition suitable for the delivery of the protein of interest, when such delivery was desired. As evidenced by UniProtKB, FPRP is the same as PTGFRN.
Thus, the claimed invention was prima facie obvious at the time of its effective filing date.
6. Claims 1, 3-15, and 18-20 are rejected under 35 U.S.C. 103 as being unpatentable over Cortin et al. taken with all Smith et al., Whitford et al., Petiot et al., and Clinke et al., in further view of both Yim et al. and Spetzler et al. (PGPUB 2016/0069889).
The teachings of Cortin et al., Smith et al., Whitford et al., Petiot et al., and Clinke et al. are applied as above for claims 1, 3-14, 19, and 20. Cortin et al., Smith et al., Whitford et al., Petiot et al., and Clinke et al. do not teach exosomes overexpressing BASP1 (claims 15 and 18). Yim et al. teach efficient loading of exosomes with a protein of interest by transfecting HEK293 cells with plasmids encoding a fusion between the protein and the exosome-associated tetraspanin CD9 or CD81; the exosomes are useful for the intracellular delivery of proteins of interest in vitro and in vivo; the protein of interest could be the pro-apoptotic protein Bax (see Abstract; p. 2, column 1, third paragraph and paragraph bridging columns 1 and 2; p. 4, paragraph bridging columns 1 and 2; paragraph bridging p. 7 and 8). While Yim et al. does not teach BASP1, Spetzler et al. teach that, similar to CD9 and CD81, BASP1 is an abundant exosomal membrane protein (see p. 24, Table 2). One of skill in the art would have found obvious to modify the teachings of Cortin et al., Smith et al., Whitford et al. Petiot et al., and Clinke et al. by further overexpressing a fusion between BASP1 and a protein of interest (such as Bax) to achieve the predictable result of obtaining a composition suitable for the delivery of the protein of interest, when such delivery was desired.
With respect to MARCKS or MARCKSL1 (claim 18), it is noted that there is no evidence of record that specifically using MARCKS or MARCKSL1 leads to unexpected results over using CD9, CD81, and BASP1 as taught by the cited prior art. Using MARCKS or MARCKSL1 is not significant if it does not provide a novel feature.
Thus, the claimed invention was prima facie obvious at the time of its effective filing date.
Response to Arguments
7. The applicant argues that Cortin teaches away from the claimed recirculation rate because the proposed modification would be unsatisfactory for the intended purpose of improving the viral titers.
This is not found persuasive because the rejection is based on collecting the conditioned medium from Cortin’s uninfected HEK293S cells (see p. 860, column 2, first full paragraph and Fig. 1; p. 862, column 2, second paragraph). As the applicant points out, the prior art is good for all it teaches.
Clinke teaches that a flow rate of 300 or 700 ml/min in the recirculation loop maintains a high cell density in a single hollow fiber for a prolonged time. One of skill in the art, seeking to obtain high exosome production from the conditioned medium harvested from the HEK293S uninfected cells, would have found obvious to use a flow rate in the recirculation loop between 300 and 700 ml/min, once the desired cell density was reached. Cortin does not teach or suggest that a higher recirculation rate could not be used once the desired density of uninfected cells is reached.
The argument of no motivation to combine Cortin with Clinke is not found persuasive because it is just an argument not supported by any evidence. Furthermore, there is no requirement for the motivation to be expressed in the cited references. The test for obviousness is not whether the features of a secondary reference may be bodily incorporated into the structure of the primary reference; nor is it that the claimed invention must be expressly suggested in any one or all of the references. Rather, the test is what the combined teachings of the references would have suggested to those of ordinary skill in the art. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981). In this case, the combined teachings of the cited prior art suggest using higher recirculation rates for obtaining increased EV amounts from uninfected HEK293S cells, once the desired cell density was obtained.
The applicant argues that the examiner did not provide a motivation for one of skill in the art to increase recirculation rate for increasing viral titer.
This argument is not material to the rejection because the rejection is not based on using high recirculation rate for increasing the viral titer.
In response to applicant's argument that the examiner's conclusion of obviousness is based upon improper hindsight reasoning, it must be recognized that any judgment on obviousness is in a sense necessarily a reconstruction based upon hindsight reasoning. But so long as it takes into account only knowledge which was within the level of ordinary skill at the time the claimed invention was made, and does not include knowledge gleaned only from the applicant's disclosure, such a reconstruction is proper. See In re McLaughlin, 443 F.2d 1392, 170 USPQ 209 (CCPA 1971).
The argument of unexpected results is not found persuasive. The rejection is not based on replacing batch or fed batch culture with perfusion culture. The primary reference already teaches culturing the cells in a bioreactor using a tangential flow perfusion hollow fiber device.
The argument that Ohno, Yim, Stipp and Spetzler do not cure the deficiencies of Cortin, Smith, Whitford, Petiot, and Clinke is not found persuasive because there is no deficiency to be cured in the combined teachings of Cortin, Smith, Whitford, Petiot, and Clinke.
Conclusion
THIS ACTION IS MADE FINAL. Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
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/ILEANA POPA/Primary Examiner, Art Unit 1633