Mechanism of resistance to trastuzumab and molecular sensitization via ADCC activation by exogenous expression of HER2-extracellular domain in human cancer cells

Trastuzumab, a humanized antibody targeting HER2, exhibits remarkable therapeutic efficacy against HER2-positive breast and gastric cancers; however, acquired resistance presents a formidable obstacle to long-term tumor responses in the majority of patients. Here, we show the mechanism of resistance to trastuzumab in HER2-positive human cancer cells and explore the molecular sensitization by exogenous expression of HER2-extracellular domain (ECD) in HER2-negative or trastuzumab-resistant human cancer cells. We found that long-term exposure to trastuzumab induced resistance in HER2-positive cancer cells; HER2 expression was downregulated, and antibody-dependent cellular cytotoxicity (ADCC) activity was impaired. We next examined the hypothesis that trastuzumab-resistant cells could be re-sensitized by the transfer of non-functional HER2-ECD. Exogenous HER2-ECD expression induced by the stable transfection of a plasmid vector or infection with a replication-deficient adenovirus vector had no apparent effect on the signaling pathway, but strongly enhanced ADCC activity in low HER2-expressing or trastuzumab-resistant human cancer cells. Our data indicate that restoration of HER2-ECD expression sensitizes HER2-negative or HER2-downregulated human cancer cells to trastuzumab-mediated ADCC, an outcome that has important implications for the treatment of human cancers

Dramatic pain relief and resolution of bone inflammation following pamidronate in 9 pediatric patients with persistent chronic recurrent multifocal osteomyelitis (CRMO)

<p>Abstract</p> <p>Background</p> <p>Chronic recurrent multifocal osteomyelitis (CRMO) is an inflammatory, non-infectious osteopathy that affects predominantly patients ≤ 18 years of age. There is no uniformly effective treatment. Our objective is to describe clinical, magnetic resonance imaging (MRI), and bone resorption response to intravenous pamidronate in pediatric CRMO.</p> <p>Methods</p> <p>We report our prospectively documented experience with all CRMO patients treated with pamidronate between 2003 and 2008 at a tertiary pediatric centre. Pamidronate was administered as intravenous cycles. The dose of pamidronate varied among subjects but was given as monthly to every 3 monthly cycles depending on the distance the patient lived from the infusion center. Maximum cumulative dose was ≤ 11.5 mg/kg/year. Pamidronate treatment was continued until resolution of MRI documented bone inflammation. Visual analog scale for pain (VAS) and bone resorption marker urine N-telopeptide/urine creatinine (uNTX/uCr) were measured at baseline, preceding each subsequent pamidronate treatment, at final follow-up, and/or at time of MRI confirmed CRMO flare. MRI of the affected site(s) was obtained at baseline, preceding every 2^ndtreatment, and with suspected CRMO recurrence.</p> <p>Results</p> <p>Nine patients (5 F: 4 M) were treated, with a median (range) age at treatment of 12.9 (4.5–16.3) years, and median (range) duration of symptoms of 18 (6–36) months. VAS decreased from 10/10 to 0–3/10 by the end of first 3–day treatment for all patients. The mean (range) time to complete MRI resolution of bone inflammation was 6.0 (2–12) months. The mean (confidence interval (CI)) baseline uNTX/uCr was 738.83 (CI 464.25, 1013.42)nmol/mmol/creatinine and the mean (CI) decrease from baseline to pamidronate discontinuation was 522.17 (CI 299.77, 744.56)nmol/mmol/creatinine. Median (range) of follow-up was 31.4 (24–54) months. Four patients had MRI confirmed CRMO recurrence, which responded to one pamidronate re-treatment. The mean (range) uNTX/uCr change as a monthly rate from the time of pamidronate discontinuation to flare was 9.41 (1.38–19.85)nmol/mmol/creatinine compared to -29.88 (-96.83–2.01)nmol/mmol/creatinine for patients who did not flare by the time of final follow-up.</p> <p>Conclusion</p> <p>Pamidronate resulted in resolution of pain and MRI documented inflammation in all patients. No patient flared while his/her uNTX/uCr remained suppressed. We propose that pamidronate is an effective second-line therapy in persistent CRMO.</p

Effect of Lysine, Vitamin B6, and Carnitine Supplementation on the Lipid Profile of Male Patients With Hypertriglyceridemia: A 12-Week, Open-Label, Randomized, Placebo-Controlled Trial

Background: Fat metabolism is known to be altered in hypertriglyceridemia. Fat oxidation requires carnitine, which can be obtained either from the diet (animal or dairy products) or through synthesis in the body using both lysine and vitamin B6. Objective: The goal of this study was to investigate the effect of lysine, vitamin B6, and carnitine supplementation on both glycemia and the lipid profiles, specifically triglyceride (TG) levels, in men with hypertriglyceridemia. Methods: This 12-week, randomized, placebo-controlled clinical trial was conducted at a Lebanese medical center. A total of 85 hypertriglyceridemic (TGandgt; 150 mg-dL) male patients were randomized to 1 of 5 groups and given supplements of lysine (1 g-d), vitamin B6 (50 mg-d), lysine (1 g-d) + vitamin B6 (50 mg-d), carnitine (1 g-d), or placebo for 12 weeks. The lipid profile (TG, total cholesterol, LDL-C, and HDL-C) and fasting plasma glucose levels were assessed at baseline and at 6 and 12 weeks. Results: Adults (~50 years) Lebanese males from a low socioeconomic status in Beirut were given the appropriate supplements. Vitamin B6 supplementation was associated with a significant reduction in total cholesterol and HDL-C of ~10percent. In addition, plasma TG was reduced by 36.6 mg-dL at 6 weeks, whereas levels in the placebo group increased by 18 mg-dL; this difference failed to reach statistical significance. No major changes in the lipid profile were observed in the lysine and carnitine groups or when lysine was added to vitamin B6. Conclusion: Vitamin B6 supplementation in these male patients with hypertriglyceridemia reduced plasma total cholesterol and HDL-C concentrations. © 2012 Elsevier HS Journals, Inc.Sibai Abla-Mehio, 2008, CVD Prevention and Control, V3, DOI 10.1016-j.precon.2007.06.002; BRADY PS, 1987, BIOCHEM J, V246, P641; BRATTSTROM L, 1990, SCAND J CLIN LAB INV, V50, P873, DOI 10.3109-00365519009104955; BROWNLEE M, 1984, DIABETES, V33, P532, DOI 10.2337-diabetes.33.6.532; Chen W, 1998, AM J CLIN NUTR, V67, P221; CHO YO, 1990, J NUTR, V120, P258; Derosa G, 2003, CLIN THER, V25, P1429, DOI 10.1016-S0149-2918(03)80130-3; DIONYSSIOUASTERIOU A, 1986, BIOCHEM MED METAB B, V36, P114, DOI 10.1016-0885-4505(86)90114-3; DUNN WA, 1982, J BIOL CHEM, V257, P7948; GODSLAND IF, 1990, NEW ENGL J MED, V323, P1375, DOI 10.1056-NEJM199011153232003; GONEN B, 1981, DIABETES, V30, P875, DOI 10.2337-diabetes.30.10.875; Gropper S. S., 2005, ADV NUTR HUMAN METAB; HAFFNER SM, 1993, J CLIN ENDOCR METAB, V77, P1610, DOI 10.1210-jc.77.6.1610; Harripersad R, 1997, INT J VITAM NUTR RES, V67, P95; Hatchcock JN, 2006, REGUL TOXICOL PARMAC, V46, P23; Iritani N, 1997, J NUTR, V127, P1077; Kalogeropoulou D, 2009, AM J CLIN NUTR, V90, P314, DOI 10.3945-ajcn.2008.27381; KHAN L, 1979, J NUTR, V109, P24; Krajcovicova-Kudlackova M, 2000, PHYSIOL RES, V49, P399; Obeid O, 2008, ECOL FOOD NUTR, V47, P298, DOI 10.1080-03670240701821337; Peeke PM, 1995, ANN NY ACAD SCI, V771, P655; Pejic RN, 2006, HEART, V92, P1529; Pellett Peter L., 2004, Food and Nutrition Bulletin, V25, P107; PREGNOLATO P, 1994, INT J VITAM NUTR RES, V64, P263; Rahbar AR, 2005, EUR J CLIN NUTR, V59, P592, DOI 10.1038-sj.ejcn.1602109; SHEPARD DC, 1985, BIOCHEM ARCH, V1, P143; Sulochana KN, 2001, IND J BIOCH BIOPHY, V18, P277; Sulochana KN, 2002, MED SCI MONITOR, V8, pR132; TANPHAICHITR V, 1976, J NUTR, V106, P111; Tome D, 2007, J NUTR, V137, p1642S; TULLY DB, 1994, FASEB J, V8, P343; Vaz FM, 2002, BIOCHEM J, V361, P417, DOI 10.1042-0264-6021:3610417; Yuan G, 2007, CAN MED ASSOC J, V176, P1113, DOI 10.1503-cmaj.06096343