) A& g% D. w: ]. y {+ }& H7 V$ S }/ B+ b有意思的是,+ y% o. v/ q K! _' c2 x- V* \" d
Ki67的阳性比例常与细胞死亡的频度成正比。那么是细胞增殖多导致了死亡多,还是细% s' l9 t N- _( E' T
胞死亡多导致了增殖多呢?如果是前者,应该是细胞死亡越多,则患者预后越好。但事实是,细胞死亡越8 ?+ X' f6 b P; a1 S! r$ U, a
多,患者的生存期常越短。所以,死亡增多导致增殖增加的推测更为合理。 , R: o% V0 p+ W 5 H% ]5 p* m y4 ^) ?
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! q U( _' f) X- e- N: S ( R/ s7 D { X# h" o: F* a9 N这样看来, % d. X2 J9 {! ]/ r, SKi67" m" q6 i; s' R
是一个预后不好的标记。但话分两头说。对肿瘤化疗敏感的常是处于细胞增殖周期的2 u4 l' U4 Y3 l
细胞,那些9 v4 W. r5 S) D) w; R
G04 Z3 |/ |: m2 X7 Q
期的细胞一般对化疗没有什么反应。所以, " I8 H- P K8 b, t( |9 BKi67比例高的肿瘤往往对化疗敏感,化疗效果 3 O! g, _1 {! V4 |" `$ N好。 1 _" X$ M8 T# U! C/ a# q2 m" R : _ f) B- R# n$ y; O简单地说,Ki67标记的是处于增殖周期中的细胞。3 t' C7 W) G4 _" ~- c' _) X1 P5 T
该标记阳性率越高,肿瘤生长越快,组织分化越差,对化疗也越敏感。一般来说,预后较差。$ P" E9 C' S" ]! v
First- and second-generation EGFR TKIs are established first line therapy for patients with NSCLC with activating mutations in EGFR. Unfortunately, patients ultimately develop disease progression with acquisition of a second-site EGFR T790M mutation in more than half of cases. This has led to the development of third generation EGFR TKIs which inhibit both the EGFRm+ and T790M mutations in preclinical models and are showing activity in TKI-resistant patients in Phase I studies. Despite the potential improvements brought by third generation EGFR-TKIs, advanced EGFRm+ tumor cells will still remain highly adaptable and the inevitability of further resistance will limit the effectiveness of these drugs. As such, the identification of resistance mechanisms to these agents is essential to guide future therapeutic strategies and identify novel:novel combinations. 5 o& c4 M2 ]/ f1 O) n" {7 {% {; B+ U( B To interrogate resistance to AZD9291, we have generated panels of EGFRm+ cell lines resistant to gefitinib (first generation TKI) and EGFRm+ and EGFRm+/T790M cell lines resistant to afatinib and AZD9291 (second and third generation TKIs, respectively). Subsequently, we characterised the cell lines using a variety of molecular profiling techniques including Next Generation Sequencing (NGS), Affymetrix gene expression analysis, and phenotypic profiling following pharmacological modulation by small molecule inhibitors of canonical signaling pathways.8 D; a0 E0 w- m' z& Z% Z# ^% i
The effects on cell survival across the range of resistant models by a panel of pathway inhibitors indicated that resistance to the EGFR inhibitors, in particular AZD9291, is frequently associated with increased sensitivity to selumetinib (AZD6244; ARRY-142886) (MEK1/2 inhibitor), suggesting that ERK signaling is commonly reactivated to circumvent inhibition of the EGFR pathway. Molecular characterisation of the panel of cell lines suggests a range of different resistance mechanisms may be responsible for reactivation of ERK signaling, including a decrease in negative regulators of ERK such as DUSP6 or an epithelial to mesenchymal transition consistent with previous observations.6 p- [* ^5 z7 J/ E7 f" z
Collectively, these data suggest that combining an EGFR TKI with a MEK inhibitor could prevent or delay resistance and drive superior duration of benefit from these agents. 7 H6 o, ^5 c8 S2 W1 h- c) S