The main function of GAB1 is to enhance PI3K/AKT activation thereby prolonging MAPK signaling [12]. While RAS/RAF/MEK/ERK signaling cascade usually ends up in cellular proliferation and tumorigenic transformation, enhanced AKT-kinase signaling usually is entailed with evasion of apoptosis, which is the turning-point

RG7420 in drug resistance formation [13]. Given this, TKI can interrupt signaling cascades evading apoptosis, thereby re-sensitizing cancer cells to induction of apoptosis. Figure 1 gives a schematic overview of the molecular mechanisms of action of TKI. Figure 1 Schematic model of tumorigenic signaling pathways and their inhibition by anti-cancer-TKI. Challenges of generic TKI drugs in cancer therapy According to their European Birth Date during the past decade, these substances successively will be running off-patent

within the next years (Table 1). From a regulatory point of view, this raises the question how marketing authorization applications (MAA) should be filed and especially, how therapeutic equivalence should be established for generic applications. In general, demonstrated bioequivalence (BE) allows generic medicinal products to refer to the efficacy and safety data of the originator medicinal product. It is easy to anticipate, that numerous questions in this regard will arise in the near future. Aqueous (non-complicated) intravenously applied drug products have a 100% bioavailability directly per definition, thus, no BE studies are required for a MAA of such generic drugs. However, for orally applied Tau-protein kinase drug products,

BE with the originator selleck screening library product needs to be shown, which may be done using patients or healthy selleck compound volunteers in respective in vivo studies or by means of comparative in-vitro investigations. Since decades BE-acceptance criteria for AUC and Cmax require the 90% confidence intervals being completely within 80 – 125% (for AUC and Cmax) to assume BE. The acceptance range may be tightened to 90 – 111% for one or both pharmacokinetic characteristics according to the European BE-Guideline [14] in the case of narrow therapeutic index drugs (NTID). In cases of class I and III compounds having identified not to have a narrow therapeutic index – specific in-vitro dissolution data may substitute for human BE-studies considering also particular requirements on excipients. This concept follows the principles of the biopharmaceutical classification system (BCS) [14]. It is likely that numerous questions in regard to the appropriate data package will arise in the near future including questions on the appropriate study design, on the appropriate study population, nutrition status, single or repeated dose-design, appropriate BCS classification of the individual compound or the classification as NTID. MAA for new generics may be processed via different regulatory authorizations routes, i.e.