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作者:疑夕
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' }. }/ d% y) A) r, B2 I8 mOn December 15, 2014, Patrick Soon Shiong, the richest physician in the world, acquired 19.9% of Sorrento Therapeutics (NASDAQ: SRNE)’s equity at $5.80 per share (about 41.7 million). Four days later, Sorrento and Conkwest announced an agreement to co-develop CAR-NK immunotherapy. Sorrento’s stock price reached a high of $11.38 on January 15, 2015.( J- N% C) {& I' S; e- E2 F' ? c
B. N( `4 K' g" d; DCAR-T cell immunotherapy has been regarded as one of the most compelling breakthroughs in cancer treatment in recent years. Companies working on CAR-T (e.g., JUNO, KITE, BLCM, BLUE, ZIOP) are red hot at present. Sorrento/Conkwest is developing CAR-expressing NK cells rather than T cells to kill cancer cells. How about CAR-TNK compares to CAR-T?
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Here is a comparison published in OncoImmunology[1]. The author, Hans Klingemann, is the inventor of the NK-92 cell line and co-founded ZelleRx in 2002, which was renamed Conkwest in 2010. CAR-NK has many several advantages over CAR-T:
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(1) CAR-NK cells don’t produce IL-6 which is associated with the cytokine release syndrome. A series of patient deaths in the trials of CAR-T were linked to unusually high levels of IL-6.
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' W8 I ]# f* R! O v(2) CAR-NK cells disappear relatively rapidly from the circulation owing to their limited lifespan. There is no concern about persisting CAR-associated side effects. Whereas Juno Therapeutics has to insert EGFRt gene into the CAR-T cells to control them.7 B" } _6 I" y D) F
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(3) NK cells are known as serial killers which diligently moves from one target to the next one, killing on as many as 7-10 cells.
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(4) The transfection efficiency of NK-92 cells is about 50%, even with non-viral methods. Avoiding viral vectors eliminates the risks of oncogene activation and insertional mutagenesis., V6 g9 f! y8 a/ ^
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(5) CAR-NK cells can also be produced in large scaleunder GMP conditions. Moerover, it may be used in the setting of allogeneic transplantation.
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Naturally, only about 10% of circulating lymphocytes are NK cells. The activation of NK cells is determined by the balance of inhibitory and activating receptor stimulation. MHC class I molecules in normal cells inhibit the activation of NK cells.$ b* Z @6 n9 M, n
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Natural NK cells do not express antigen specific receptors. Can CAR-NK cells equipped with an antigen specific receptor kill cancer cells as effectively as CAR-T cells? Hard to say.
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+ l) b$ z7 \; @+ x$ {3 j( u, OPreclinical studies in leukemia, lymphoma, and multiple myeloma have been reported. For instance, treatment with anti-CS1 CAR-NK cells prolonged the survival of multiple myeloma mice from 40 days to 50 days[2].' J/ r* O) t) E
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Sorrento intends to develop anti-CD19, anti-PDL1, anti-PSMA, and anti-CD123 CAR-NK cells. It is expected to initiate Phase I trials in 2016., e; i- R& I/ `3 u |- m* O9 C' C6 i% ]* T
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[1] Oncoimmunology. 2014, 3, e28147. doi: 10.4161/onci.28147.$ b R; v- p0 R% D. X3 i) q
[2] Leukemia. 2014, 28(4), 917-927. ! u* o# M _/ q( \. [( t
2 T$ ?+ ~8 x6 {7 L% J- X' |$ E$ t fRelated Articles:
. N5 c% a' V7 T5 ]; p9 fWhat are the next generation T cell immunotherapies |
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