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 .
Election/Restrictions
Applicant's election with traverse of the invention of the invention of Group 1 (claims 16-27) in the reply filed on 03/12/2026 is acknowledged. The traversal is on the ground(s) that the common technical feature of the EVs of the claims are a special technical feature in view of the art. This is not found persuasive because the prior art provides for EVs that were isolated from supernatants via size exclusion chromatography (SEC) from cells that were cultured in a 3D hydrogel culture platform using chitosan and alginate (Millar et al (2018). As such the Examiner maintains that the common technical feature of the claimed inventions is not a special technical feature in view of the prior art.
The requirement is still deemed proper and is therefore made FINAL.
Claim 27 and 28 are withdrawn from further consideration pursuant to 37 CFR 1.142(b), as being drawn to a nonelected invention, there being no allowable generic or linking claim. Applicant timely traversed the restriction (election) requirement in the reply filed on 03/12/2026.
Claim Objections
Claim 16 is objected to because of the following informalities: line 13 of the claims recites “cell-specific Evs”, where the phrase “cell-specific EVs” (capital V in the abbreviation for extracellular vesicles) is likely intended. Appropriate correction is required.
Claim Rejections - 35 USC § 112 - Indefiniteness
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claims 16-27 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
Claims 16-27 are unclear over recitation of the limitation “on the cell culture support”, as recited in step a) of claim 16 because there is no antecedent basis for any “cell culture support”.
Claims 16-27 are unclear over recitation of the limitation “adding a cell culture medium to the hydrogel resulting from the cross-linking”, as recited in step c) of claim 16 because there is no antecedent basis for any “hydrogel”. The claims may be made more clear in this regard of step b) is amended to include an explicit requirement for a hydrogel production, such as:
b) creating a hydrogel by contacting the said Schiff base cross-linking electrophilic substrate with isolated solid cancer cells in suspension in N-succinyl chitosan to trigger a Schiff base cross- linking reaction between the Schiff base cross-linking electrophilic substrate and the N-succinyl chitosan;
Claim Rejections - 35 USC § 103
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.
Claim(s) 16-25 is/are rejected under 35 U.S.C. 103 as being unpatentable over Millan et al (2018) in view of Kletzmayr et al (06 February 2020; cited on the IDS of 08/23/2023) and Thippabhotla et al (2019; cited on the PTO-892 of 01/15/2026).
Millan et al teaches the using a polysaccharide-based hydrogel comprising chitosan and alginate to culture cancer cells in 3D and the isolation of extracellular vesicles (EVs) from supernatants using size exclusion chromatography. Millan et al does not provide particular details related to the 3D culture platform or the isolation of EVs, but discloses that the platform was “previously” introduced.
Kletzmayr et al teaches a platform for the 3D culturing of cancer cells in polysaccharide hydrogels including simultaneous encapsulation of cancer cells within composite hydrogels of chitosan and alginate based on Schiff base crosslinking (e.g.: p.2, left col). Relevant to the limitations of steps a)-d) of claim 16, Kletzmayr et al teaches applying oxidized alginate (oxAlg) (relevant to claim 17) to a solid support, and contacting cells in suspension with N-succinyl-chitosan (sChi) for 15 minutes (relevant to claim 18) followed by addition of cell culture medium and subsequent replacement of media every 3-4 days, where the oxAlg and sChi trigger a spontaneous Schiff base reaction and formation a hydrogel in the presence of cells (e.g.: Fig. 1; p.9 – Experimental section).
Relevant to claim 19, Kletzmayr et al teaches oxAlg with an oxidation degree of about 40% (e.g.: Fig 1D) at 1.0% w/v, and sChi that is 85% deacetylated, 500 mPas viscosity, about 35% N-substituted, and 0.8% w/v in PBS (e.g.: Fig 1C; p.9 - Cell Culture).
Relevant to claims 20 and 21, Kletzmayr et al teaches resuspended in sChi at 2.0 × 106 cells mL−1, and making a hydrogel with 5ul of cell suspension and 10ul of oxAlg, meeting the broad limitations of the densities of the claims.
Relevant to clams 16 and 22-24, Kletzmayr et al teaches 3D cultures of cells in hydrogel including SKOV3 (human ovarian cancer cell line), A549 (human alveolar basal epithelial cell line), and LNCaP (human prostate cancer cell line). Note that page 9 of the specification as filed provides that “solid cancer cells are selected from primary solid cancer cells and cells of solid cancer cell lines”.
Kletzmayr et al does not teach steps of collecting EVs from hydrogel cell cultures (relevant to steps d)-f) of claim 16, and claim 25), but such steps related to creating and isolating EVs from cancer cells were known in the prior art and are taught by Thippabhotla et al.
Thippabhotla et al teaches the isolation of EVs from 3D hydrogel cultures including the use of exosome depleted media, incubation with depleted media under conditions were EVs are secreted, and the collection of EVs (relevant to steps d)-f) of claim 16) (e.g.: p.9 - 2D and 3D cell culture; p.10 - EV isolation and NTA analysis). The reference provides that EVs were isolated by methods including centrifugation and filtration, relevant to claim 25.
It would have been prima facie obvious to someone with ordinary skill in the relevant art before the effective filing date of the rejected claims to prepare EVs from cancer cells ex-vivo, as taught by Millan et al, using the 3D culture platform taught by Kletzmayr et al and EV collection methods of Thippabhotla et al. The skilled artisan would have been motivated to use the particular 3D platform of Kletzmayr et al based on the expressed teachings of Millan et al et al that EVs isolated from a hydrogel comprising chitosan and alginate have a particular EV production, and the based on the expressed teachings of Kletzmayr et al which provide specific methods of creating a hydrogel comprising chitosan and alginate for the 3D culture of cells. The skilled artisan would have been motivated to used the EV isolation methods of Thippabhotla et al because Millan et al teaches the analysis of EV cargo and enrichment of tumour-associated antigens from cancer cells cultured in 3D exhibit, and Thippabhotla et al specifically teaches the analysis of EV contents of EVs isolated from 3D cultures of cancer cells.
Claim(s) 26 and 27 is/are rejected under 35 U.S.C. 103 as being unpatentable over Millan et al (2018) in view of Kletzmayr et al (06 February 2020; cited on the IDS of 08/23/2023) and Thippabhotla et al (2019; cited on the PTO-892 of 01/15/2026). as applied to claims 16-25 above, and further in view of Anderson et al (US PG Pub 20190008902).
Millan et al in view of Kletzmayr et al and Thippabhotla et al renders obvious the methods of claim 6, from which instantly rejected claims 26 and 27 depend. Further relevant to instantly rejected claim 27, Millan et al teaches EVs isolated from supernatants via size exclusion chromatography, which is a method that separates EVs from soluble proteins.
Millan et al in view of Kletzmayr et al and Thippabhotla et al does not specifically provide for the concentration of collected culture medium contain EVs. However, such methods in the preparation of EVs were known in the prior art and are taught by Anderson et al.
Anderson et al teaches methods for purification of cell-derived vesicles, including EVs (e.g.: p.10, para 0102), and teaches that vesicles can be purified using methods that remove soluble proteins (e.g.: paras 0079, 0121) and include the concentrating of media that contains the vesicles (e.g.: paras 0012, 0032, 0121-0124).
It would have been prima facie obvious to someone with ordinary skill in the relevant art before the effective filing date of the rejected claims to have included the methods of Anderson et al in the preparation of EVs according to the methods rendered obvious by Millan et al in view of Kletzmayr et al and Thippabhotla et al. Where Anderson et al teaches methods for the isolation of EVs from media, the use of the methods of Anderson would have been the simple substitution of one known method for another with predictable results.
Conclusion
No claim is allowed.
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Stephen Kapushoc
Primary Examiner
Art Unit 1683
/STEPHEN T KAPUSHOC/Primary Examiner, Art Unit 1683
Prosecution Insights