Anti-cancer effect of metformin by suppressing signaling pathway of HER2 and HER3 in tamoxifen-resistant breast cancer cells.

Development of new therapeutic strategies is becoming increasingly important to overcome tamoxifen resistance. Recently, much interest has been focused on anti-tumor effects of metformin commonly used to treat type II diabetes. Increased protein expression and signaling of epidermal growth factor receptor (EGFR) family is a possible mechanism involved in tamoxifen resistance. Since HER2/HER3 heterodimers are able to induce strong downstream signaling and activate various biological responses such as cellular proliferation and growth, we investigated the anti-cancer effect of metformin by inhibition of signaling pathway via downregulation of HER2 and HER3 using tamoxifen-resistant MCF-7 (TR MCF-7) cells. Compared to MCF-7 cells, TR MCF-7 cells showed increased expression of EGFR, HER2, and HER3, and metformin inhibited the expression of these proteins in a dose- and time-dependent manner. Metformin inhibited activation of HER2 (Tyr1248)/HER3 (Tyr1289)/Akt (Ser473) as well as cell proliferation and colony formation by estrogenic promotion in MCF-7 and TR MCF-7 cells. Known as a HER3 ligand, heregulin (HRG)-ß1-induced phosphorylation of HER2, HER3 and Akt, and protein interaction of HER2/HER3 and colony formation were inhibited by metformin in both cells. Consistent with the results in the two cell lines, we identified that metformin inhibited HER2/HER3/Akt signaling axis activated by HRG-ß1 using the HER2 and HER3-overexpressing breast cancer cell line SK-BR-3. Lastly, lapatinib-induced HER3 upregulation was significantly inhibited by treatment of metformin in HER3 siRNA-transfected TR MCF-7 cells. These data suggest that metformin might overcome tamoxifen resistance through the inhibition of expression and signaling of receptor tyrosine kinase HER2 and HER3.

Antagonistic effects of indoloquinazoline alkaloids on antimycobacterial activity of evocarpine.

AIMS: The interaction of quinolone and indoloquinazoline alkaloids concerning their antimycobacterial activity was studied. METHODS AND RESULTS: The antimycobacterial and modulating activity of evodiamine (1), rutaecarpine (2) and evocarpine (3) was tested on mycobacteria including three multidrug-resistant (MDR) clinical isolates of Mycobacterium tuberculosis. Antagonistic effects were concluded from fractional inhibitory concentration (FICI) values. Interaction energies of the compounds were calculated using GLUE docking module implemented in GRID. 1 and 2 exhibited weak inhibition of rapidly growing mycobacteria, however, 1 was active against Myco. tuberculosis H37Rv (MIC = 10 mg l(-1) ) while 2 was inactive. Both 1 and 2 showed a marked antagonistic effect on the susceptibility of different mycobacterial strains to 3 giving FICI values between 5 and 9. The interaction energies between compounds 1 and 2 with compound 3 suggested the possibility of complex formation in solution. CONCLUSIONS: Indoloquinazoline alkaloids markedly reduce the antimycobacterial effect of the quinolone alkaloid evocarpine. Complex formation may play a role in the attenuation of its antimycobacterial activity. SIGNIFICANCE AND IMPACT OF THE STUDY: This study gives a striking example of antagonism between compounds present in the same plant extract which should be considered in natural product based screening projects.

Dihydroquinazolinone inhibitors of proliferation of blood and liver stage malaria parasites.

Drugs that target both the liver and blood stages of malaria will be needed to reduce the disease's substantial worldwide morbidity and mortality. Evaluation of a 259-member library of compounds that block proliferation of the blood stage of malaria revealed several scaffolds--dihydroquinazolinones, phenyldiazenylpyridines, piperazinyl methyl quinolones, and bis-benzimidazoles--with promising activity against the liver stage. Focused structure-activity studies on the dihydroquinazolinone scaffold revealed several molecules with excellent potency against both blood and liver stages. One promising early lead with dual activity is 2-(p-bromophenyl)-3-(2-(diethylamino)ethyl)-2,3-dihydroquinazolin-4(1H)-one with 50% effective concentrations (EC50s) of 0.46 µM and 0.34 µM against liver stage Plasmodium berghei ANKA and blood stage Plasmodium falciparum 3D7 parasites, respectively. Structure-activity relationships revealed that liver stage activity for this compound class requires a 3-dialkyl amino ethyl group and is abolished by substitution at the ortho-position of the phenyl moiety. These compounds have minimal toxicity to mammalian cells and are thus attractive compounds for further development.

Characterization of the inhibitor binding site in mitochondrial NADH-ubiquinone oxidoreductase by photoaffinity labeling using a quinazoline-type inhibitor.

The diverse inhibitors of bovine heart mitochondrial complex I (NADH-ubiquinone oxidoreductase) are believed to share a common large binding domain with partially overlapping sites, though it remains unclear how these binding sites relate to each other. To obtain new insight into the inhibitor binding domain in complex I, we synthesized a photoreactive azidoquinazoline {[(125)I]-6-azido-4-(4-iodophenethylamino)quinazoline, [(125)I]AzQ}, in which a photolabile azido group was introduced into the toxophoric quinazoline ring to allow specific cross-linking, and carried out a photoaffinity labeling study using bovine heart submitochondrial particles. Analysis of the photo-cross-linked proteins by peptide mass fingerprinting and immunoblotting revealed that [(125)I]AzQ specifically binds to the 49 kDa and ND1 subunits with a frequency of approximately 4:1. The cross-linking was completely blocked by excess amounts of other inhibitors such as acetogenin and fenpyroximate. Considerable cross-linking was also detected in the ADP/ATP carrier and 3-hydroxybutyrate dehydrogenase, though it was not associated with dysfunction of the two proteins. The partial proteolysis of the [(125)I]AzQ-labeled 49 kDa subunit by V8-protease and N-terminal sequencing of the resulting peptides revealed that the amino acid residue cross-linked by [(125)I]AzQ is within the sequence region Thr25-Glu143 (118 amino acids). Furthermore, examination of fragment patterns generated by exhaustive digestion of the [(125)I]AzQ-labeled 49 kDa subunit by V8-protease, lysylendopeptidase, or trypsin strongly suggested that the cross-linked residue is located within the region Asp41-Arg63 (23 amino acids). The present study has revealed, for the first time, the inhibitor binding site in complex I at the sub-subunit level.

The potent protein kinase C-selective inhibitor AEB071 (sotrastaurin) represents a new class of immunosuppressive agents affecting early T-cell activation.

There is a pressing need for immunosuppressants with an improved safety profile. The search for novel approaches to blocking T-cell activation led to the development of the selective protein kinase C (PKC) inhibitor AEB071 (sotrastaurin). In cell-free kinase assays AEB071 inhibited PKC, with K(i) values in the subnanomolar to low nanomolar range. Upon T-cell stimulation, AEB071 markedly inhibited in situ PKC catalytic activity and selectively affected both the canonical nuclear factor-kappaB and nuclear factor of activated T cells (but not activator protein-1) transactivation pathways. In primary human and mouse T cells, AEB071 treatment effectively abrogated at low nanomolar concentration markers of early T-cell activation, such as interleukin-2 secretion and CD25 expression. Accordingly, the CD3/CD28 antibody- and alloantigen-induced T-cell proliferation responses were potently inhibited by AEB071 in the absence of nonspecific antiproliferative effects. Unlike former PKC inhibitors, AEB071 did not enhance apoptosis of murine T-cell blasts in a model of activation-induced cell death. Furthermore, AEB071 markedly inhibited lymphocyte function-associated antigen-1-mediated T-cell adhesion at nanomolar concentrations. The mode of action of AEB071 is different from that of calcineurin inhibitors, and AEB071 and cyclosporine A seem to have complementary effects on T-cell signaling pathways.

A specific inhibitor of the epidermal growth factor receptor tyrosine kinase.

A small molecule called PD 153035 inhibited the epidermal growth factor (EGF) receptor tyrosine kinase with a 5-pM inhibition constant. The inhibitor was specific for the EGF receptor tyrosine kinase and inhibited other purified tyrosine kinases only at micromolar or higher concentrations. PD 153035 rapidly suppressed autophosphorylation of the EGF receptor at low nanomolar concentrations in fibroblasts or in human epidermoid carcinoma cells and selectively blocked EGF-mediated cellular processes including mitogenesis, early gene expression, and oncogenic transformation. PD 153035 demonstrates an increase in potency over that of other tyrosine kinase inhibitors of four to five orders of magnitude for inhibition of isolated EGF receptor tyrosine kinase and three to four orders of magnitude for inhibition of cellular phosphorylation.

Accidental afloqualone intoxication in two dogs.

Two dogs presented to the emergency service after accidental ingestion of afloqualone tablets, a muscle relaxant used for back pain in humans. Toxic effects of the drug in these dogs included vomiting, respiratory depression, seizures, ataxia, bradycardia, and hematuria. Treatment consisted of fluid diuresis, furosemide, and propofol. Flumazenil, a gamma-amino butyric acid antagonist, was administered intravenously; however, it was not effective in stopping the seizures in these dogs. Both dogs recovered with supportive treatment. To the authors' knowledge, this is the first documented report of afloqualone intoxication in dogs.

Antifolate polyglutamylation and competitive drug displacement at dihydrofolate reductase as important elements in leucovorin rescue in L1210 cells.

Previous studies from this laboratory have shown that the addition of leucovorin to tumor cells dissociates methotrexate, but not methotrexate polyglutamates, from dihydrofolate reductase (L. H. Matherly, D. W. Fry, and I. D. Goldman, Cancer Res., 43: 2694-2699, 1983). To further assess the importance of these interactions to leucovorin rescue, antifolate growth inhibition toward L1210 cells in the presence of leucovorin was correlated with the metabolism of (6S)-5-formyl tetrahydrofolate to dihydrofolate as a measure of dihydrofolate reductase activity. Growth inhibition (greater than 95%) by methotrexate (5-10 microM) following its intracellular polyglutamylation during a 3-h preexposure, or by continuous treatment with high levels of the lipophilic antifolate, trimetrexate (1 microM), was only slightly diminished by 10 microM leucovorin (15-25%). High-pressure liquid chromatographic analyses of the derivatives formed from radiolabeled (6S)-5-formyl tetrahydrofolate under these conditions showed an incomplete conversion to dihydrofolate and metabolism to predominantly 10-formyl tetrahydrofolate. Neither of the antifolates interfered appreciably with the metabolism of the folate derivatives to polyglutamates. Growth inhibition in the presence of leucovorin correlated with the accumulation of dihydrofolate (1.5-2.2 nmol) from radiolabeled (6S)-5-formyl tetrahydrofolate, reflecting continued suppression of dihydrofolate reductase activity at these drug concentrations. With lower equitoxic levels of the trimetrexate (7.5 nM), the provision of leucovorin allowed for a restoration of cell growth to a level greater than 90% of control. Under these conditions, control levels of dihydrofolate (0.2 nmol) were formed from radiolabeled cofactor, consistent with sustained dihydrofolate reductase activity. These findings support a role for the activation of dihydrofolate reductase as an important component of the reversal of the effects of diaminoantifolates by leucovorin, presumably by a competitive displacement of drug from the enzyme. Since no displacement occurs in cells which have accumulated methotrexate polyglutamates, or in the presence of high levels of trimetrexate, it appears that the concentration of unbound drug within cells is a significant determinant of the extent of this competitive binding interaction. From these considerations, the high levels of methotrexate polyglutamates that accumulate in sensitive tumors relative to bone marrow and gastrointestinal cells would appear to represent an important factor for the selectivity of leucovorin rescue in vivo.

Ferroptosis is induced following siramesine and lapatinib treatment of breast cancer cells.

Ferroptosis is an iron-dependent, oxidative cell death, and is distinct from apoptosis, necrosis and autophagy. In this study, we demonstrated that lysosome disrupting agent, siramesine and a tyrosine kinase inhibitor, lapatinib synergistically induced cell death and reactive oxygen species (ROS) in MDA MB 231, MCF-7, ZR-75 and SKBr3 breast cancer cells over a 24 h time course. Furthermore, the iron chelator deferoxamine (DFO) significantly reduced cytosolic ROS and cell death following treatment with siramesine and lapatinib. Furthermore, we determined that FeCl3 levels were elevated in cells treated with siramesine and lapatinib indicating an iron-dependent cell death, ferroptosis. To confirm this, we treated cells with a potent inhibitor of ferroptosis, ferrastatin-1 that effectively inhibited cell death following siramesine and lapatinib treatment. The increase levels of iron could be due to changes in iron transport. We found that the expression of transferrin, which is responsible for the transport of iron into cells, is increased following treatment with lapatinib alone or in combination with siramesine. Knocking down of transferrin resulted in decreased cell death and ROS after treatment. In addition, ferroportin-1 (FPN) is an iron transport protein, responsible for removal of iron from cells. We found its expression is decreased after treatment with siramesine alone or in combination with lapatinib. Overexpression FPN resulted in decreased ROS and cell death whereas knockdown of FPN increased cell death after siramesine and lapatinib treatment. This indicates a novel induction of ferroptosis through altered iron regulation by treating breast cancer cells with a lysosome disruptor and a tyrosine kinase inhibitor.

Determination of apoptosis, uracil incorporation, DNA strand breaks, and sister chromatid exchanges under conditions of thymidylate deprivation in a model of BER deficiency.

Thymidylate synthase (TS) is an important target of several chemotherapeutic agents. During TS inhibition, dTTP levels decrease with a subsequent increase in dUTP. Uracil incorporated into the genome is removed by base excision repair (BER). BER has been hypothesized to play a role in the response to thymidylate deprivation, despite a lack of direct evidence. We previously found that beta-pol null murine fibroblasts were approximately six-fold more resistant than wild-type cells to raltitrexed, a folate-based inhibitor specific for TS. In this study, a number of endpoints were determined to understand the influence of BER and beta-pol during raltitrexed treatment. Raltitrexed induced apoptosis in wild-type cells to a greater extent than in beta-pol null cells. A PARP inhibitor decreased the sensitivity to raltitrexed, although the extent was not different between wild-type and beta-pol null cells. No evidence was seen for extensive strand break formation that preceded apoptosis, although raltitrexed induced more sister chromatid exchanges in wild-type cells. Increased levels of uracil in DNA were detected following treatment in wild-type and beta-pol null cells. However, uracil levels were only approximately two-fold higher in DNA from treated cells compared to untreated. Uracil DNA glycosylase activity was slightly higher in beta-pol null cells, although not sufficiently different to explain the difference in sensitivity to raltitrexed. Taken together, the data suggest that the sensitivity of the wild-type cells to raltitrexed is not associated with activation of PARP-1 dependent BER, extensive uracil incorporation into DNA and persistent strand breaks, but rather with changes suggestive of DNA recombination.

Epidermal growth factor receptor modulation of radiation response: preclinical and clinical development.

Approximately two thirds of all human solid tumors derive from epithelial tissues. The epidermal growth factor receptor (EGFR) serves as an important regulator of cellular growth in epithelial tumors. A spectrum of new anticancer agents have been specifically designed to target the EGFR in an effort to inhibit malignant growth. Although several of these new drugs show single-agent activity in early clinical trials, the predominant growth effect of EGFR signaling inhibition is cytostatic. However, the interaction of EGFR inhibition combined with conventional cytotoxic therapies (radiation and chemotherapy) is more potent, and shows great promise in the treatment of a variety of solid tumors that overexpress this receptor. This report focuses primarily on the capacity of EGFR inhibitors to modulate cellular and overall tumor response to ionizing radiation.

Actions of quazodine (MJ1988) on smooth muscle.

1. Quazodine (MJ1988; 6,7-dimethoxy-4-ethyl-quinazoline) relaxed a variety of vascular and extravascular smooth muscle preparations and antagonized, non-competitively, several substances which contract smooth muscle.2. This activity was not due to beta-adrenoceptor stimulation or to alpha-adrenoceptor blockade.3. On the rabbit duodenum, the inhibitory effect was qualitatively similar to that of theophylline and was antagonized by the phosphodiesterase potentiator, imidazole.4. The activity of quazodine was similar to, but up to 18 times greater than, that of theophylline and it is suggested that at least part of its activity on vascular and extravascular smooth muscle is due to inhibition of phosphodiesterase.

Modulation of anti-metabolite effects. Effects of thymidine on the efficacy of the quinazoline-based thymidylate synthetase inhibitor, CB3717.

CB3717 (N-(4-(N-((2-amino-4- hydroxy-6-quinazolinyl)methyl)prop-2-ynylamino ) benzoyl)-L-glutamic acid) is an antitumour agent that inhibits thymidylate synthetase (TS). A dose-dependent fall in plasma thymidine (dThd) (1.43 microM to 0.47 microM) occurred in non-tumour-bearing mice following the administration of CB3717. Further, in mice carrying the L1210/CBRI tumour, the drug's antitumour properties were ablated by co-administration of dThd, an effect consistent with TS being the cytotoxic locus. In vitro studies of protection by dThd against CB3717 cytotoxicity were carried out in an attempt to quantify this reversal. The metabolism of [14C]-dThd was measured in cultures of L1210 cells (10(4)/ml) exposed to a completely cytotoxic dose of CB3717 (50 microM). The cytotoxicity of the drug was only expressed when the dThd concentration (0.5-2 microM) had fallen to less than 0.1 microM in the media. This reduction was due to: (1) dThd incorporation into DNA, (2) catabolism of dThd to thymine. By reducing the initial cell concentration to 10(3)/ml the depletion of dThd was substantially reduced and consequently cells continued to grow for a longer period. The critical concentration of dThd, below which growth in the presence of CB3717 could not be supported was estimated to be between 0.026 and 0.1 microM. Thus even the minimum level of dThd achieved in vivo was still in excess of that required for protection from CB3717 toxicity in vitro. There was a small accumulation of deoxyuridine (dUrd) (approximately 2-fold) in mouse plasma 24 hr after completion of a 5-day course of CB3717 (200 mg/kg) but in vitro studies demonstrated that this was unlikely to modulate CB3717 toxicity in the presence of dThd. We caution against the use of rodent tumour models (or human tumour xenografts) for antitumour or toxicity testing of compounds designed to inhibit the de novo synthesis of thymidylate; they may be misleading because the high dThd levels found in these animals compared with man may mask the cytotoxic effects of these drugs.

Leucovorin antagonizes the effects of trimetrexate on mouse hemopoietic progenitors.

Trimetrexate (2, 4, diamino -5- methyl - 6 [3, 4, 5, trimethoxyanilino) methyl] quinazoline) (TMQ) is a non-classic folate antagonist that is used as an antineoplastic and antipneumocystis agent with promising results. TMQ and methotrexate (MTX) toxicities are comparable. Leucovorin (N-5-formyltetrahydrofolate) (LV) is used to prevent the toxic effects of MTX. In this study the effects of LV on TMQ induced hemopoietic progenitor damage are studied in a murine model. Changes of pluripotent stem cells (colony forming units spleen, CFU-S), granulocyte-macrophage committed progenitors (GM-CFC), erythroid committed progenitor (BFU-E) levels in the bone marrow were followed after administration to mice of a single dose of TMQ or of simultaneous injection of TMQ and LV. Results show that the latter significantly reduces the effects of the former on peripheral blood cells and on hemopoietic progenitors.

Synthesis, cytotoxicity, and inhibitory effects on tubulin polymerization of a new 3-heterocyclo substituted 2-styrylquinazolinones.

In order to study the influence of 3-substitution on the cytotoxic activity of 2-styrylquinazolinones, new 6-chloro-2-styryl-3-(heteroaryl)-4(3H)-quinazolinones were synthesized by refluxing equimolar amounts of 6-chloro-2-methyl-3-(heteroaryl)-4(3H)-quinazolinones and benzaldehyde in glacial acetic acid. At 1 microg ml(-1) concentration, almost all 2-styrylquinazolinones showed some cytotoxic activity against the L1210 and K562 leukemia cell lines. However, only 6-chloro-2-styryl-3-(pyrimidin-2yl)-4(3H)-quinazolinone inhibited the growth of these cells by over 50%. This last compound was also the only member of the series that inhibited tubulin polymerization, with an IC(50) value of 5.8 versus 3.2 microM for colchicine. It was also examined for effects on the growth of human MCF7 breast carcinoma cells and Burkitt lymphoma CA46 cells, which had IC(50) values of 0.34 and 1.0 microM, respectively. At 10 microM 6-chloro-2-styryl-3-(pyrimidin-2yl)-4(3H)-quinazolinone induced G2/M arrest (66%) in Burkitt cells, with a mitotic index of 20%. At 3.4 microM, it caused disruption of the cellular microtubule system of the MCF7 cells. Both these cellular effects are consistent with its mechanism of action resulting from its inhibitory effect on tubulin assembly.

[Ca++ ion transport blockers as reversants of the drug resistance of malarial parasites. 2. The effect of praziquantel on the resistance to chloroquine and compound R-70-Zh of Plasmodium berghei]. / Blokatory transporta ionov Ca++ kak reversanty lekarstvennoi ustoichivosti maliariinykh parazitov. Soobshchenie 2. Vliianie prazikvantelia na ustoichivost' k khlorokhinu i soedineniiu R-70-Zh u Plasmodium berghei.

The reversing action of anthelminthic praziquantel (P) on the effect of chloroquine (C) and compound R-70-Zh (styrylquinazoline) was revealed on a Plasmodium berghei model (white inbred mice), using a LNK65 isolate with naturally reduced sensitivity to chloroquine and its polyresistant line LNK65CHLFR with acquired resistance to chloroquine/fansidar (selected in our laboratory). P (125 mg/kg) in combination with C showed a potentiating effect not only on the LNK65 isolate, but also on the LNK65CHLFR line, while investigated separately on this line, both drugs were not effective in tested doses. Moreover, the similar effect of C on the LNK65CHLFR line was achieved in the dose that was 4 times higher than that of P/C combination. P in a standard dose on the LNK65 isolate showed a more marked activation of compound R-70-Zh that on C. The potentiating effect was manifested in combination with R-70-Zh in the dose half as high as that of C; this phenomenon was also reflected by the efficiency index (5.0 against the 4.0) accepted in our laboratory and may be associated with the higher sensitivity of the LNK65 isolate to R-70-Zh. P showed some antimalarial action which manifested itself only by morphological changes on P. berghei parasites similar to those observed under the action of some dihydropholate reductase inhibitors, such as pyrimethamine.

The DPP-4 inhibitor linagliptin restores ß-cell function and survival in human isolated islets through GLP-1 stabilization.

CONTEXT: Inhibition of dipeptidyl peptidase-4 (DPP-4) is a potent strategy to increase glucose-dependent insulinotropic polypeptide and glucagon like peptide 1 (GLP-1) induced insulin secretion in diabetes. It is important to know whether new drugs approved for the treatment of type 2 diabetes have direct effects on the ß-cell. OBJECTIVE: Herein we investigated the effect of linagliptin, a novel DPP-4 inhibitor, on ß-cell function and survival. DESIGN: Human islets were exposed to a diabetic milieu (11.1-33.3 mM glucose, 0.5 mM palmitate, the mixture of 2 ng/mL IL-1ß+1000 U/mL interferon-γ, or 50 µM H2O2) with or without 500 ng/mL IL-1 receptor antagonist (IL-1Ra) or 30-50 nM linagliptin. RESULTS: Linagliptin restored ß-cell function and turnover, which was impaired when islets were exposed to elevated glucose, palmitate, cytokines, or H2O2. Pretreatment with IL-1Ra was similarly effective, except against H2O2 treatment. Nitrotyrosine concentrations in islet lysates, an indicator of oxidative stress, were highly elevated under diabetic conditions but not in islets treated with linagliptin or IL-1Ra. Linagliptin also reduced cytokine secretion and stabilized GLP-1 in islet supernatants. CONCLUSIONS: We show that the novel DPP-4 inhibitor linagliptin protected from gluco-, lipo-, and cytokine-toxicity and stabilized active GLP-1 secreted from human islets. This provides a direct GLP-1 mediated protective effect of linagliptin on ß-cell function and survival.

A phase II study of trastuzumab emtansine in patients with human epidermal growth factor receptor 2-positive metastatic breast cancer who were previously treated with trastuzumab, lapatinib, an anthracycline, a taxane, and capecitabine.

PURPOSE: To determine whether the antibody-drug conjugate trastuzumab emtansine (T-DM1), which combines human epidermal growth factor receptor 2 (HER2) -targeted delivery of the potent antimicrotubule agent DM1 with the antitumor activity of trastuzumab, is effective in patients with HER2-positive metastatic breast cancer (MBC) who have previously received all standard HER2-directed therapies. PATIENTS AND METHODS: In this single-arm phase II study, T-DM1 3.6 mg/kg was administered intravenously every 3 weeks to patients with HER2-positive MBC who had prior treatment with trastuzumab, lapatinib, an anthracycline, a taxane, and capecitabine. The primary objectives were overall response rate (ORR) by independent review and safety. RESULTS: Among 110 pretreated patients (median, seven prior agents for MBC; median follow-up, 17.4 months), the ORR was 34.5% (95% CI, 26.1% to 43.9%), clinical benefit rate was 48.2% (95% CI, 38.8% to 57.9%), median progression-free survival (PFS) was 6.9 months (95% CI, 4.2 to 8.4 months), and median duration of response was 7.2 months (95% CI, 4.6 months to not estimable). In patients with confirmed HER2-positive tumors (n = 80 by retrospective central testing), the response rate was 41.3% (95% CI, 30.4% to 52.8%), and median PFS was 7.3 months (95% CI, 4.6 to 12.3 months). Most adverse events were grades 1 to 2; the most frequent grade ≥ 3 events were thrombocytopenia (9.1%), fatigue (4.5%), and cellulitis (3.6%). CONCLUSION: T-DM1 is well tolerated and has single-agent activity in patients with HER2-positive MBC who have previously received both approved HER2-directed therapies and multiple chemotherapy agents. T-DM1 may be an effective new treatment for this patient population.

EGFR and EML4-ALK gene mutations in NSCLC: a case report of erlotinib-resistant patient with both concomitant mutations.

The fusion gene EML4-ALK (echinoderm microtubule-associated protein-like 4 gene and the anaplastic lymphoma kinase gene) was recently identified as a novel genetic alteration in non-small cell lung cancer (NSCLC). EML4-ALK translocations correlate with specific clinical and pathological features, in particular lack of EGFR and K-ras mutations, and may be associated with resistance to EGFR tyrosine-kinase inhibitors (TKIs). Here, we report a case of a patient with a concomitant EGFR mutation and ALK translocation resistant to erlotinib. Considering this report, ALK status should be investigated in unexplained cases of EGFR-TKI-resistance of EGFR mutated NSCLCs.

Antitumor activity of a novel EGFR tyrosine kinase inhibitor against human lung carcinoma in vitro and in vivo.

Treatment with epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) has led to dramatic clinical improvement in selected patients with non-small cell lung cancer (NSCLC). However, intrinsic and acquired resistance to EGFR-TKI remains a common phenomenon. Novel EGFR-TKI, structurally different with erlotinib or gefitinib might be beneficial for patients with NSCLC. In this study, we examined the antitumor effect of a newly synthesized novel EGFR tyrosine kinase inhibitor (Zhao260054). In vitro studies in a panel of four different human lung cancer cell lines revealed that Zhao260054 inhibited cell proliferation with high potency and induced G(0)/G(1) arrest of cell cycle and apoptosis. Zhao260054 markedly reduced phosphorylation of EGFR and inhibited activation of ERK1/2 and AKT. Oral administration of Zhao260054 (200 mg/kg/day) to BALB/c nude mice bearing SPC-A1 xenografts significantly retarded tumor growth. In conclusion, Zhao260054 has potent antitumor activity on human lung cancer in vitro and in vivo.