POS0512 ANTI-CITRULLINATED PROTEIN ANTIBODY SEROSTATUS DETERMINES 2-YEAR RETENTION OF IV AND SC ABATACEPT IN PATIENTS WITH RA IN A REAL-WORLD SETTING

Background

A treat-to-target approach for RA management is recommended.1,2 However, up to half of patients discontinue DMARD treatment within 18 months.2 Predictive biomarkers, such as anti-citrullinated protein antibodies (ACPAs) and RF, may be useful to stratify patients to the most appropriate treatment. ACTION (AbataCepT In rOutiNe clinical practice; NCT02109666) and ASCORE (Abatacept SubCutaneOus in Routine Clinical PracticE; NCT02090556) were 2-year, international, observational, prospective, multicenter studies of IV and SC abatacept, respectively, for the treatment of RA in routine clinical practice.3,4 Higher retention has been previously reported in patients with double ACPA/RF seropositive RA compared with double ACPA/RF seronegative RA.3,4

Objectives

To assess the independent effect of ACPA or RF single seropositivity on abatacept retention in patients with RA receiving abatacept in a post hoc analysis of ACTION and ASCORE.

Methods

This post hoc analysis included patients aged ≥ 18 years, with active moderate-to-severe RA (ACR/EULAR 2010 criteria) who initiated IV (body weight–adjusted dosing) or SC (125 mg once weekly) abatacept.3,4 Patients were stratified by baseline ACPA/RF status: ACPA+/RF− (ACPA+ only), ACPA/RF double positive (+/+), ACPA−/RF+ (RF+ only), and ACPA/RF double negative (−/−). Abatacept retention rate at 2 years was estimated by Kaplan–Meier (KM) analysis.

Results

Patients with ACPA/RF serostatus data from the ACTION and ASCORE studies (N = 1679 and N = 1748, respectively) were evaluated. Baseline demographic and disease characteristics were similar across studies and serostatus groups (Table 1). In patients with ACPA+ only RA, abatacept retention rates were similar to the +/+ group and greater than the RF+ only and −/− groups (Figure 1). In ASCORE (Figure 1A), retention rates were significantly higher in ACPA+ only and +/+ groups when compared with the −/− group. In contrast, retention rates for patients with RF+ only RA were not significantly different vs −/− patients. Results were similar in ACTION, although the higher retention in the ACPA+ group did not reach statistical significance (Figure 1B).

Table 1.

Baseline demographics and disease characteristics by ACPA/RF status for the ASCORE and ACTION studies

ASCORE+/+RF+ onlyACPA+ only−/−(n = 1079)(n = 142)(n = 184)(n = 343)Age, years57.1 (12.8)58.2 (11.8)57.4 (13.5)57.8 (13.9)DAS28 (CRP)4.7 (1.2)4.6 (1.1)4.4 (1.0)4.8 (1.2)CDAI26.6 (12.5)25.8 (12.0)23.6 (10.9)28.2 (13.2)SDAI28.1 (13.0)27.2 (12.4)24.4 (10.8)29.7 (13.9)ACTION+/+RF+ onlyACPA+ only−/−(n = 1028)(n = 161)(n = 98)(n = 392)Age, years58.2 (12.0)58.4 (13.4)58.5 (14.0)57.0 (13.3)DAS28 (CRP)4.9 (1.1)5.0 (1.1)4.9 (1.0)5.0 (1.1)CDAI28.7 (12.2)29.2 (12.4)28.7 (11.5)30.1 (12.9)SDAI30.4 (13.1)31.2 (13.4)29.8 (11.5)31.7 (13.4)

Data are mean (SD). Patients with missing data for baseline ACPA/RF status are excluded.

Conclusion

In this post hoc analysis of the real-world ACTION and ASCORE studies, ACPA positivity was associated with an increased likelihood of retention over 2 years. Patients with ACPA+ only RA were equally as likely to be retained on abatacept as patients with ACPA/RF double positivity. In contrast, patients with RF+ only RA were less likely to be retained on abatacept over 2 years. These findings suggest that ACPA positivity played a more important role than RF positivity in abatacept retention. The higher retention seen in patients with ACPA+ only vs RF+ only disease demonstrates the key role of ACPA in RA and supports the importance of precision medicine in treating patients.

References

[1]Fraenkel L, et al. Arthritis Care Res (Hoboken) 2021;73:924–39.

[2]Smolen JS, et al. Ann Rheum Dis 2020;79:685–99.

[3]Alten R, et al. Clin Rheumatol 2019;38:1413–24.

[4]Alten R, et al. Ann Rheum Dis 2021;80(suppl 1):OP0180.

Acknowledgements

This study was sponsored by Bristol Myers Squibb. Medical writing and editorial assistance was provided by Fiona Boswell, PhD, of Caudex, and was funded by Bristol Myers Squibb. Study management provided by Syneos (CRO).

Disclosure of Interests

Rieke Alten Speakers bureau: AbbVie, Bristol Myers Squibb, Celltrion, Galapagos, Gilead, Janssen, Lilly, Novartis, Pfizer, Roche, Paid instructor for: AbbVie, Bristol Myers Squibb, Celltrion, Galapagos, Gilead, Janssen, Lilly, Novartis, Pfizer, Roche, Consultant of: AbbVie, Bristol Myers Squibb, Celltrion, Galapagos, Gilead, Janssen, Lilly, Novartis, Pfizer, Roche, Grant/research support from: AbbVie, Bristol Myers Squibb, Celltrion, Galapagos, Gilead, Janssen, Lilly, Novartis, Pfizer, Roche, Christiane Rauch Shareholder of: Bristol Myers Squibb, Employee of: Bristol Myers Squibb, Melanie Chartier Shareholder of: Bristol Myers Squibb, Employee of: Bristol Myers Squibb, M.T. Nurmohamed Speakers bureau: AbbVie, Bristol Myers Squibb, Eli Lilly, Janssen, Pfizer, Consultant of: AbbVie, Bristol Myers Squibb, Eli Lilly, Janssen, Pfizer, Grant/research support from: AbbVie, Amgen, Bristol Myers Squibb, Eli Lilly, Galapagos, Janssen, MSD, Pfizer, Sean Connolly Shareholder of: Bristol Myers Squibb, Employee of: Bristol Myers Squibb, Maya H Buch Speakers bureau: AbbVie, Consultant of: AbbVie, Galapagos, Gilead, Pfizer, Grant/research support from: Gilead, Pfizer, UCB, Peter Peichl Speakers bureau: GlaxoSmithKline, Janssen, Xavier Mariette Consultant of: Bristol Myers Squibb, Galapagos, GlaxoSmithKline, Janssen, Novartis, Pfizer, Sanofi, UCB, Yusuf Patel: None declared, Sara Marsal Speakers bureau: Bristol Myers Squibb, Lilly, MSD, Novartis - Sandoz, Pfizer, Roche, Consultant of: AbbVie, Galapagos, Pfizer, Sanofi; IMIDomics (executive role), Grant/research support from: AbbVie, Bristol Myers Squibb, Galapagos, Janssen, Lilly, MSD, Novartis - Sandoz, Pfizer, Roche, Sanofi, UCB, Roberto Caporali Speakers bureau: AbbVie, Amgen, Bristol Myers Squibb, Celltrion, Fresenius-Kabi, Galapagos, Janssen, Lilly, MSD, Novartis, Pfizer, Roche, Sandoz, UCB, Consultant of: AbbVie, Amgen, Bristol Myers Squibb, Celltrion, Galapagos, Janssen, Lilly, MSD, Novartis, Pfizer, Sandoz, UCB, Hedley Griffiths Consultant of: Amgen, Raimón Sanmartí Speakers bureau: AbbVie, Bristol Myers Squibb, Lilly, MSD, Pfizer, Roche, Sanofi, Grant/research support from: AbbVie, Bristol Myers Squibb, MSD, Pfizer, Roche, Bettina Bannert Speakers bureau: Novartis Pharma Schweiz AG, Yedid Elbez Consultant of: Bristol Myers Squibb, Employee of: Signifience, Karissa Lozenski Shareholder of: Bristol Myers Squibb, Employee of: Bristol Myers Squibb.

POS0107 ACPA POSITIVITY DETERMINES REMISSION IN PATIENTS WITH RA TREATED WITH IV AND SC ABATACEPT: A POST HOC ANALYSIS OF THE REAL-WORLD OBSERVATIONAL ACTION AND ASCORE STUDIES

Background

The goal of treatment for RA is achieving low disease activity and/or remission1,2; however, disease course and management can be complicated by additional factors that may be influenced by serostatus. Anti-citrullinated protein antibodies (ACPAs) and RF contribute to a more severe RA disease pattern3 and may be useful in predicting response to treatment.4 ACTION (AbataCepT In rOutiNe clinical practice; NCT02109666) and ASCORE (Abatacept SubCutaneOus in Routine Clinical PracticE; NCT02090556) were 2-year, international, observational, prospective, multicenter studies of IV and SC abatacept, respectively, for the treatment of RA in routine clinical practice.4,5 Previous analyses have shown that ACPA/RF double-positive serostatus was associated with better treatment outcomes compared with ACPA/RF double-negative serostatus.4–6

Objectives

To assess the independent effect of ACPA or RF single seropositivity among patients with RA on achieving remission after treatment with abatacept for 2 years, and to compare outcomes among patients with single versus double serostatus.

Methods

This post hoc analysis included patients from ACTION and ASCORE who initiated IV (body weight–adjusted dosing) or SC abatacept (125 mg once weekly), respectively. Patients were stratified by baseline ACPA/RF status: ACPA+/RF− (ACPA+ only), ACPA/RF double positive (+/+), ACPA−/RF+ (RF+ only), and ACPA/RF double negative (−/−). DAS28 (CRP) and CDAI remission rates (defined as < 2.6 and 0–2.8, respectively) at 2 years for patients who were ACPA+ or RF+ only at baseline were assessed and compared with those who were +/+ and −/−. Patients with missing baseline ACPA/RF status were excluded. Last observation carried forward efficacy analyses were used to impute missing values.

Results

This analysis included 1679 patients from ACTION (ACPA+ only, n = 98; +/+, n = 1028; RF+ only, n = 161; and −/−, n = 392) and 1748 patients from ASCORE (ACPA+ only, n = 184; +/+, n = 1079; RF+ only, n = 142; and −/−, n = 343). Across studies and serogroups, baseline demographics and disease characteristics were similar (data not shown). In both ACTION and ASCORE, a higher proportion of patients who were only ACPA+ achieved DAS28 (CRP) and CDAI remission at 2 years compared with patients who were only RF+ (Figure 1). Additionally, a similar proportion of patients who were only ACPA+ achieved DAS28 (CRP) and CDAI remission at 2 years compared with patients who were +/+. In contrast, a lower proportion of patients who were only RF+ achieved DAS28 (CRP) and CDAI remission at 2 years compared with patients who were +/+.

Conclusion

In this post hoc analysis of real-world data from ACTION and ASCORE, ACPA positivity was associated with an increased likelihood of achieving DAS28 (CRP) and CDAI remission at 2 years. Patients who were ACPA+ only were as likely to achieve remission as +/+ patients, suggesting that RF serostatus had less influence than ACPA serostatus on remission status at 2 years. In line with this, patients who were RF+ only were less likely to achieve remission at 2 years. This is the first large, real-world study to show that ACPA positivity plays a more important role than RF positivity in achieving remission whilst on abatacept. These results highlight the importance of assessing baseline ACPA status when considering treatment options for patients with RA.

References

[1]Smolen JS, et al. Ann Rheum Dis 2020;79:685–99.

[2]Fraenkel L, et al. Arthritis Care Res (Hoboken) 2021;73:924–39.

[3]Katchamart, W, et al. Rheumatol Int 2015;35:1693–9.

[4]Alten R, et al. Ann Rheum Dis 2021;80(suppl 1):OP0180.

[5]Alten R, et al. Clin Rheumatol 2019;38:1413–24.

[6]Alten R, et al. RMD Open 2017;3:e000345.

Acknowledgements

This study was sponsored by Bristol Myers Squibb. Medical writing and editorial assistance was provided by Rachel Rankin, PhD, of Caudex, and was funded by Bristol Myers Squibb. Study management provided by Syneos (CRO).

Disclosure of Interests

Rieke Alten Speakers bureau: AbbVie, Bristol Myers Squibb, Celltrion, Galapagos, Gilead, Janssen, Lilly, Novartis, Pfizer, Roche, Paid instructor for: AbbVie, Bristol Myers Squibb, Celltrion, Galapagos, Gilead, Janssen, Lilly, Novartis, Pfizer, Roche, Consultant of: AbbVie, Bristol Myers Squibb, Celltrion, Galapagos, Gilead, Janssen, Lilly, Novartis, Pfizer, Roche, Grant/research support from: AbbVie, Bristol Myers Squibb, Celltrion, Galapagos, Gilead, Janssen, Lilly, Novartis, Pfizer, Roche, Christiane Rauch Shareholder of: Bristol Myers Squibb, Employee of: Bristol Myers Squibb, Melanie Chartier Shareholder of: Bristol Myers Squibb, Employee of: Bristol Myers Squibb, M.T. Nurmohamed Speakers bureau: AbbVie, Bristol Myers Squibb, Eli Lilly, Janssen, Pfizer, Consultant of: AbbVie, Bristol Myers Squibb, Eli Lilly, Janssen, Pfizer, Grant/research support from: AbbVie, Amgen, Bristol Myers Squibb, Eli Lilly, Galapagos, Janssen, MSD, Pfizer, Sean Connolly Shareholder of: Bristol Myers Squibb, Employee of: Bristol Myers Squibb, Maya H Buch Speakers bureau: AbbVie, Consultant of: AbbVie, Galapagos, Gilead, Pfizer, Grant/research support from: Gilead, Pfizer, UCB, Peter Peichl Speakers bureau: Janssen, GlaxoSmithKline, Xavier Mariette Consultant of: Bristol Myers Squibb, Galapagos, GlaxoSmithKline, Janssen, Novartis, Pfizer, Sanofi, UCB, Yusuf Patel: None declared, Sara Marsal Speakers bureau: Bristol Myers Squibb, Lilly, MSD, Novartis - Sandoz, Pfizer, Roche, Consultant of: AbbVie, Galapagos, Pfizer, Sanofi; IMIDomics (executive role), Grant/research support from: AbbVie, Bristol Myers Squibb, Galapagos, Janssen, Lilly, MSD, Novartis - Sandoz, Pfizer, Roche, Sanofi, UCB, Roberto Caporali Speakers bureau: AbbVie, Amgen, Bristol Myers Squibb, Celltrion, Fresenius-Kabi, Galapagos, Janssen, Lilly, MSD, Novartis, Pfizer, Roche, Sandoz, UCB, Consultant of: AbbVie, Amgen, Bristol Myers Squibb, Celltrion, Galapagos, Janssen, Lilly, MSD, Novartis, Pfizer, Sandoz, UCB, Hedley Griffiths Consultant of: Amgen, Raimón Sanmartí Speakers bureau: AbbVie, Bristol Myers Squibb, Lilly, MSD, Pfizer, Roche, Sanofi, Grant/research support from: AbbVie, Bristol Myers Squibb, MSD, Pfizer, Roche, Bettina Bannert: None declared, Yedid Elbez Consultant of: Bristol Myers Squibb, Employee of: Signifience, Karissa Lozenski Shareholder of: Bristol Myers Squibb, Employee of: Bristol Myers Squibb

POS0447 PHYSICAL FUNCTION IN PATIENTS WITH RA, STRATIFIED BY SEROSTATUS AND TREATMENT LINE, FOLLOWING SC ABATACEPT: POST HOC ANALYSIS OF AN OBSERVATIONAL, 2-YEAR STUDY CONDUCTED IN ROUTINE CLINICAL PRACTICE (ASCORE)

Background:

RA is characterised by the production of autoantibodies, including RF and anti-citrullinated protein antibodies (ACPAs).1 Seropositive disease is associated with poorer prognosis in patients with RA,2 and response to different treatments has been shown to vary based on ACPA status.3 ASCORE (Abatacept SubCutaneOus in Routine Clinical PracticE; NCT02090556) was a 2-year, observational, prospective, multicentre study of SC abatacept for the treatment of RA.4

Objectives:

This post hoc analysis of the ASCORE study evaluated patient-reported outcomes, assessed using HAQ-DI, by RF/ACPA serostatus and treatment line over 24 months of treatment with abatacept.

Methods:

Eligible patients, aged ≥18 years, with active moderate-to-severe RA (ACR/EULAR 2010 criteria) who were IV abatacept-naive and initiated SC abatacept 125 mg once weekly, were enrolled into two cohorts: biologic (b)DMARD-naive patients and those with ≥1 prior bDMARD treatment failure. This post hoc analysis assessed mean change from baseline in HAQ-DI score at 6, 12, 18 and 24 months in response to treatment with abatacept stratified by baseline serostatus (RF/ACPA double positive [+/+]; RF/ACPA single positive [+/−; RF+/ACPA– or RF–/ACPA+] or RF/ACPA double negative [–/–]) and by line of therapy (all patients, patients receiving abatacept as a first-line bDMARD or as a ≥ second-line bDMARD [data not shown], and those receiving abatacept following 1 [data not shown] or ≥2 prior bDMARDs). Estimates of mean difference with 95% CIs between patients with different serostatus were calculated using a t-test for all patients and within different lines of therapy.

Results:

Among 2892 eligible patients in ASCORE, 1748 patients with RF/ACPA status available at baseline were included in this analysis (1079 +/+, 326 +/– and 343 –/–). Of these, 791 patients received abatacept as a first-line bDMARD therapy and 957 as a ≥ second-line bDMARD therapy (505 patients had received ≥2 prior bDMARDs). Among all patients, mean change from baseline in HAQ-DI score at 6 months was greater for patients with +/+ RA (mean difference [95% CI]: –0.2 [–0.3, –0.0]; p=0.0068) or +/– RA (mean difference [95% CI]: –0.2 [–0.3, –0.0]; p=0.0315) versus those with –/– RA at baseline (Figure 1). Similarly, mean change (95% CI) in HAQ-DI score at 6 months was greater for patients with +/+ RA versus –/– RA among those receiving abatacept as first-line therapy (–0.2 [–0.4, –0.0]; p=0.0407) or following treatment with ≥2 bDMARDs (–0.3 [–0.5, –0.0]; p=0.0265) (Figure 1). Among patients treated with abatacept following ≥2 prior bDMARDs, mean change in HAQ-DI score was higher among patients with +/– RA versus –/– RA at 18 months (data not shown) and 24 months (Figure 1). No other significant differences were observed by serostatus or line of therapy at any other time points.

Conclusion:

Patients with RA who were RF+/ACPA+ at baseline showed an enhanced initial response to abatacept compared with those who were RF–/ACPA–. Over 24 months of treatment in this real-world setting, abatacept was equally effective as a first- or ≥ second-line therapy.

References:

[1]Scott DL, et al. Lancet 2010;376:1094–1108.

[2]Hecht C, et al. Ann Rheum Dis 2015;74:2151–2156.

[3]Harrold LR, et al. J Rheumatol 2018;45:32–39.

[4]Alten R, et al. Ann Rheum Dis 2019;78(suppl 2):A1639.

Acknowledgements:

Professional medical writing and editorial assistance was provided by Fiona Boswell, PhD, at Caudex and was funded by Bristol Myers Squibb. This study was funded by Bristol Myers Squibb.

Disclosure of Interests:

Rieke Alten Speakers bureau: AbbVie, Bristol Myers Squibb, Gilead, Janssen, Lilly, Pfizer, Consultant of: AbbVie, Bristol Myers Squibb, Gilead, Janssen, Lilly, Pfizer, Grant/research support from: AbbVie, Bristol Myers Squibb, Gilead, Janssen, Lilly, Pfizer, Xavier Mariette Consultant of: Bristol Myers Squibb, Galapagos, Gilead, GlaxoSmithKline, Janssen, Pfizer, UCB, Rene-Marc Flipo Speakers bureau: AbbVie, Bristol Myers Squibb, Janssen, Lilly, Medac, Merck Sharp & Dohme, Novartis, Pfizer, Roche-Chugai, Grant/research support from: Amgen, Janssen, Novartis, Pfizer, Roberto Caporali Speakers bureau: AbbVie, Amgen, Bristol Myers Squibb, Celltrion, Fresenius Kabi, Galapagos, Gilead, Lilly, Merck Sharp & Dohme, Pfizer, Roche, Samsung Bioepis, Sanofi, UCB, Consultant of: Galapagos, Gilead, Janssen, Lilly, Merck Sharp & Dohme, Maya H Buch Speakers bureau: AbbVie, Consultant of: AbbVie, Eli Lilly, Gilead, Merck Serono, Pfizer, Roche, Sanofi, Grant/research support from: Gilead, Pfizer, Roche, UCB, Yusuf Patel: None declared, Sara Marsal Speakers bureau: Bristol Myers Squibb, Celgene, Pfizer, Roche, Sanofi, UCB, Consultant of: AbbVie, Bristol Myers Squibb, Celgene, Galapagos, Merck Sharp & Dohme, Pfizer, Roche, Sanofi, UCB, Grant/research support from: AbbVie, Bristol Myers Squibb, Celgene, Janssen, Merck Sharp & Dohme, Novartis, Pfizer, Roche, Sanofi, UCB, M.T. Nurmohamed Speakers bureau: AbbVie, Bristol Myers Squibb, Eli Lilly, Roche, Sanofi, Consultant of: AbbVie, Celgene, Celltrion, Eli Lilly, Janssen, Grant/research support from: AbbVie, Bristol Myers Squibb, Celgene, Eli Lilly, Janssen, Merck Sharp & Dohme, Mundipharma, Novartis, Pfizer, Roche, Sanofi, Hedley Griffiths Consultant of: AbbVie, Gilead, Janssen, Novartis, Peter Peichl: None declared, Bettina Bannert: None declared, Adrian Forster: None declared, Melanie Chartier Shareholder of: Bristol Myers Squibb, Employee of: Bristol Myers Squibb, Yedid Elbez Consultant of: Bristol Myers Squibb, Christiane Rauch Shareholder of: Bristol Myers Squibb, Employee of: Bristol Myers Squibb, Karissa Lozenski Shareholder of: Bristol Myers Squibb, Employee of: Bristol Myers Squibb, Vadim Khaychuk Shareholder of: Bristol Myers Squibb, Employee of: Bristol Myers Squibb

OP0180 IMPACT OF RF AND ANTI-CITRULLINATED PROTEIN ANTIBODY SEROSTATUS ON 2-YEAR RETENTION OF ABATACEPT IN PATIENTS WITH RA

Background:

Up to 50% of patients with RA discontinue DMARD treatment within 18 months.1 However, up to 20% of patients who fail multiple treatments may have a good treatment response to another therapy.1 Predictive biomarkers, such as RF and anti-citrullinated protein antibodies (ACPAs), may be useful to stratify patients with RA to the most appropriate treatment.1 ASCORE (Abatacept SubCutaneOus in Routine Clinical PracticE; NCT02090556) was a 2-year, observational, prospective, multicentre study of SC abatacept for the treatment of RA in routine clinical practice.2

Objectives:

To determine if RF/ACPA serostatus and treatment line impact abatacept retention in patients with RA in a post hoc analysis of ASCORE.

Methods:

Eligible patients, aged ≥18 years, with active moderate-to-severe RA (ACR/EULAR 2010 criteria) who were IV abatacept-naive and initiated SC abatacept 125 mg once weekly, were enrolled into two cohorts: biologic (b)DMARD-naive patients and those with ≥1 prior bDMARD treatment failure. This post hoc analysis assessed abatacept retention rate at 2 years in a subset of patients with RF/ACPA serostatus data (n=1748) from the ASCORE study (N=2892; as observed). Baseline (BL) serostatus groups examined by treatment line were: RF/ACPA double positive (+/+) RA, RF/ACPA single positive (RF+/ACPA– or RF–/ACPA+) RA (data not shown) and RF/ACPA double negative (–/–) RA. Last observation carried forward (LOCF) analyses were used to assess change from BL and measures of disease remission (DAS28 [CRP] <2.6, CDAI ≤2.8, and SDAI ≤3.3) in patients with +/+ RA versus –/– RA.

Results:

BL demographic and disease characteristics were similar across serostatus groups and treatment lines (Table 1). Mean age was 57.1 and 57.8 years for +/+ RA and –/– RA, respectively. Mean DAS28 (CRP) was 4.7 and 4.8 for +/+ RA and –/– RA, respectively. In patients with +/+ RA, abatacept retention was greater when given as first-line treatment (57% vs 48% when given as ≥ second-line) (Figure 1). Retention was similar in patients with –/– RA regardless of treatment line. After 2 years, mean (SE) change from BL (LOCF) in DAS28 (CRP) was –1.41 (0.06) and –0.97 (0.09) for patients with +/+ and –/– RA, respectively. For patients with +/+ RA, mean (SE) change from BL in DAS28 (CRP) was –1.62 (0.08) for those in whom abatacept was first-line and –1.19 (0.08) for those in whom abatacept was ≥ second-line. For patients with –/– RA, mean (SE) change from BL in DAS28 (CRP) was –1.03 (0.13) for those in whom abatacept was first-line and –0.93 (0.12) for those in whom abatacept was ≥ second-line. Remission rates (LOCF) were significantly (p<0.0001) higher in patients with +/+ RA vs –/– RA respectively: DAS28 (CRP) 38.4% (n=393) versus 19.3% (n=62); CDAI 50.6% (n=513) versus 33.0% (n=107); and SDAI 49.5% (n=497) versus 32.5% (n=102).

Table 1.

BL demographics and disease characteristics by RF/ACPA status

+/+ RA(n=1079)–/– RA(n=343)First-line (n=511)≥ second-line (n=568)First-line(n=140)≥ second-line(n=203)Age57.1 (13.4)57.1 (12.2)59.5 (14.7)56.6 (13.2)DAS28 (CRP)4.7 (1.2)4.7 (1.2)4.8 (1.1)4.8 (1.2)CDAI26.6 (12.5)26.6 (12.4)27.7 (12.5)28.6 (13.8)SDAI28.1 (13.1)28.1 (12.9)29.1 (12.9)30.2 (14.7)

Data are mean (SD). Patients with missing data for BL RF/ACPA status are excluded.

ACPA=anti-citrullinated protein antibody; BL=baseline.

Conclusion:

In this real-world analysis, patients with +/+ RA treated with first-line abatacept had higher retention than patients receiving abatacept as a ≥ second-line therapy. Remission rates on abatacept were higher in patients with +/+ RA versus –/– RA. These results support early treatment with abatacept and highlight the importance of further evaluating precision medicine approaches in RA.

References:

[1]Smolen JS, et al. Ann Rheum Dis 2020;79:685–699.

[2]Alten R, et al. Ann Rheum Dis 2019;78(suppl 2):A1639.

Acknowledgements:

Professional medical writing and editorial assistance was provided by Lindsay Craik at Caudex and was funded by Bristol Myers Squibb. This study was funded by Bristol Myers Squibb.

Disclosure of Interests:

Rieke Alten Speakers bureau: AbbVie, Bristol Myers Squibb, Gilead, Janssen, Lilly, Pfizer, Consultant of: AbbVie, Bristol Myers Squibb, Gilead, Janssen, Lilly, Pfizer, Grant/research support from: AbbVie, Bristol Myers Squibb, Gilead, Janssen, Lilly, Pfizer, Xavier Mariette Consultant of: Bristol Myers Squibb, Galapagos, Gilead, GlaxoSmithKline, Janssen, Pfizer, UCB, Rene-Marc Flipo Speakers bureau: AbbVie, Bristol Myers Squibb, Janssen, Lilly, Medac, Merck Sharp & Dohme, Novartis, Pfizer, Roche-Chugai, Grant/research support from: Amgen, Janssen, Novartis, Pfizer, Roberto Caporali Speakers bureau: AbbVie, Amgen, Bristol Myers Squibb, Celltrion, Fresenius Kabi, Galapagos, Gilead, Lilly, Merck Sharp & Dohme, Pfizer, Roche, Samsung Bioepis, Sanofi, UCB, Consultant of: Galapagos, Gilead, Janssen, Lilly, Merck Sharp & Dohme, Maya H Buch Speakers bureau: AbbVie, Consultant of: AbbVie, Eli Lilly, Gilead, Merck Serono, Pfizer, Roche, Sanofi, Grant/research support from: Gilead, Pfizer, Roche, UCB, Yusuf Patel: None declared, Raimón Sanmartí Speakers bureau: AbbVie, Bristol Myers Squibb, Gebro, Janssen, Lilly, Merck Sharp & Dohme, Pfizer, Roche, Sanofi, Consultant of: AbbVie, Bristol Myers Squibb, Gebro, Lilly, Merck Sharp & Dohme, Pfizer, Roche, Sanofi, Grant/research support from: Bristol Myers Squibb, Merck Sharp & Dohme, Pfizer, Sara Marsal Speakers bureau: Bristol Myers Squibb, Celgene, Pfizer, Roche, Sanofi, UCB, Consultant of: AbbVie, Bristol Myers Squibb, Celgene, Galapagos, Merck Sharp & Dohme, Pfizer, Roche, Sanofi, UCB, Grant/research support from: AbbVie, Bristol Myers Squibb, Celgene, Janssen, Merck Sharp & Dohme, Novartis, Pfizer, Roche, Sanofi, UCB, M.T. Nurmohamed Speakers bureau: AbbVie, Bristol Myers Squibb, Eli Lilly, Roche, Sanofi, Consultant of: AbbVie, Celgene, Celltrion, Eli Lilly, Janssen, Grant/research support from: AbbVie, Bristol Myers Squibb, Celgene, Eli Lilly, Janssen, Merck Sharp & Dohme, Mundipharma, Novartis, Pfizer, Roche, Sanofi, Hedley Griffiths Consultant of: AbbVie, Gilead, Janssen, Novartis, Peter Peichl: None declared, Bettina Bannert: None declared, Adrian Forster: None declared, Melanie Chartier Shareholder of: Bristol Myers Squibb, Employee of: Bristol Myers Squibb, Sean Connolly Shareholder of: Bristol Myers Squibb, Employee of: Bristol Myers Squibb, Yedid Elbez Consultant of: Bristol Myers Squibb, Christiane Rauch Shareholder of: Bristol Myers Squibb, Employee of: Bristol Myers Squibb, Vadim Khaychuk Shareholder of: Bristol Myers Squibb, Employee of: Bristol Myers Squibb, Karissa Lozenski Shareholder of: Bristol Myers Squibb, Employee of: Bristol Myers Squibb

POS0599 DISEASE ACTIVITY IN PATIENTS WITH RA BY SEROSTATUS AND TREATMENT LINE, FOLLOWING TREATMENT WITH ABATACEPT: RESULTS FROM AN INTERNATIONAL OBSERVATIONAL STUDY

Background:

RF and anti-citrullinated protein antibodies (ACPAs) are associated with a severe and aggressive disease course in patients with RA.1 Abatacept is a selective co-stimulation modulator for the treatment of RA.2 ASCORE (Abatacept SubCutaneOus in Routine Clinical PracticE; NCT02090556) was a 2-year, observational, prospective, multicentre study of SC abatacept for the treatment of RA in routine clinical practice.3

Objectives:

To determine if serostatus and treatment line impacted disease activity in patients enrolled in the ASCORE study.

Methods:

Eligible patients, aged ≥18 years, with active moderate-to-severe RA (ACR/EULAR 2010 criteria) who were IV abatacept-naive and initiated SC abatacept 125 mg once weekly, were enrolled into two cohorts: biologic (b)DMARD-naive patients and those with ≥1 prior bDMARD treatment failure. This post hoc analysis assessed the mean change in disease activity (CDAI, SDAI and DAS28 [ESR]) from baseline (BL) at 6, 12, 18 and 24 months in response to treatment with abatacept. Patients were stratified by BL serostatus (all patients, RF/ACPA double positive [+/+] RA; RF/ACPA single positive [+/–; RF+/ACPA– or RF–/ACPA+] RA and RF/ACPA double negative [–/–] RA) and by line of therapy (all patients, patients receiving abatacept as a first-line or ≥ second-line therapy and those receiving abatacept following 1 or ≥2 prior bDMARDs). Overall patient data, as well as data for patients who were +/– or those who had 1 or ≥2 previous bDMARDs, are not shown. Estimates of mean difference are from t-test.

Results:

Among 2892 eligible patients in ASCORE, 1748 patients with RF/ACPA status available at BL were included in this analysis (1079 +/+ RA, 326 +/− RA and 343 −/− RA). After 6 months, patients with +/+ RA on first-line abatacept therapy had better improvements in CDAI and SDAI scores from BL than patients on ≥ second-line abatacept therapy (mean difference [95% CI]: –3.4 [–5.6, –1.1]; p=0.0032 and –3.9 [–6.5, –1.3]; p=0.0035, respectively); better improvements in SDAI were also seen after 12 months (mean difference [95% CI]: –3.5 [–6.5, –0.5]; p=0.0207). Changes in CDAI and SDAI scores were comparable after 18 and 24 months. At 6 and 12 months, patients with +/+ RA on first-line therapy had better improvements from BL in DAS28 (ESR) than those on ≥ second-line therapy (mean differences [95% CI]: –0.5 [–0.8, –0.2]; p=0.0002 and –0.4 [–0.7, –0.0]; p=0.0317, respectively); changes were comparable at 18 and 24 months (Figure 1). For patients on ≥ second-line therapy, at 18 months those with +/+ RA had better improvements from BL in DAS28 (ESR) than those with –/– RA (mean difference [95% CI]: –0.7 [–1.2, –0.1]; p=0.0232). For patients not stratified by line of therapy, changes in DAS28 (ESR) were comparable between the +/+ and –/– RA subgroups over time, with the exception of 6 months where patients with –/– RA had better improvements from BL compared with patients with +/+ RA (mean difference [95% CI]: –0.3 [–0.6, –0.0]; p=0.0495).

Conclusion:

In this real-world, post hoc analysis, patients with +/+ RA who received abatacept as a first-line therapy had greater early improvements in disease activity compared with patients who received abatacept as a ≥ second-line therapy. Improvements in disease activity at 24 months were comparable between patients who were +/+ and those who were –/–. Larger studies are needed to further corroborate these findings.

References:

[1]Katchamart W, et al. Rheumatol Int 2015;35:1693–1699.

[2]Malmström V, et al. Nat Rev Immunol 2017;17:60–75.

[3]Alten R, et al. Ann Rheum Dis 2019;78(Suppl 2):A1639.

Acknowledgements:

Professional medical writing and editorial assistance was provided by Rachel Rankin, PhD, at Caudex and was funded by Bristol Myers Squibb. This study was funded by Bristol Myers Squibb.

Disclosure of Interests:

Rieke Alten Speakers bureau: AbbVie, Bristol Myers Squibb, Gilead, Janssen, Lilly, Pfizer, Consultant of: AbbVie, Bristol Myers Squibb, Gilead, Janssen, Lilly, Pfizer, Grant/research support from: AbbVie, Bristol Myers Squibb, Gilead, Janssen, Lilly, Pfizer, Xavier Mariette Consultant of: Bristol Myers Squibb, Galapagos, Gilead, GlaxoSmithKline, Janssen, Pfizer, UCB, Rene-Marc Flipo Speakers bureau: AbbVie, Bristol Myers Squibb, Janssen, Lilly, Medac, Merck Sharp & Dohme, Novartis, Pfizer, Roche-Chugai, Grant/research support from: Amgen, Janssen, Novartis, Pfizer, Roberto Caporali Speakers bureau: AbbVie, Amgen, Bristol Myers Squibb, Celltrion, Fresenius Kabi, Galapagos, Gilead, Lilly, Merck Sharp & Dohme, Pfizer, Roche, Samsung Bioepis, Sanofi, UCB, Consultant of: Galapagos, Gilead, Janssen, Lilly, Merck Sharp & Dohme, Maya H Buch Speakers bureau: AbbVie, Consultant of: AbbVie, Eli Lilly, Gilead, Merck Serono, Pfizer, Roche, Sanofi, Grant/research support from: Gilead, Pfizer, Roche, UCB, Yusuf Patel: None declared, Raimón Sanmartí Speakers bureau: AbbVie, Bristol Myers Squibb, Gebro, Janssen, Lilly, Merck Sharp & Dohme, Pfizer, Roche, Sanofi, Consultant of: AbbVie, Bristol Myers Squibb, Gebro, Lilly, Merck Sharp & Dohme, Pfizer, Roche, Sanofi, Grant/research support from: Bristol Myers Squibb, Merck Sharp & Dohme, Pfizer, Sara Marsal Speakers bureau: Bristol Myers Squibb, Celgene, Pfizer, Roche, Sanofi, UCB, Consultant of: AbbVie, Bristol Myers Squibb, Celgene, Galapagos, Merck Sharp & Dohme, Pfizer, Roche, Sanofi, UCB, Grant/research support from: AbbVie, Bristol Myers Squibb, Celgene, Janssen, Merck Sharp & Dohme, Novartis, Pfizer, Roche, Sanofi, UCB, M.T. Nurmohamed Speakers bureau: AbbVie, Bristol Myers Squibb, Eli Lilly, Roche, Sanofi, Consultant of: AbbVie, Celgene, Celltrion, Eli Lilly, Janssen, Grant/research support from: AbbVie, Bristol Myers Squibb, Celgene, Eli Lilly, Janssen, Merck Sharp & Dohme, Mundipharma, Novartis, Pfizer, Roche, Sanofi, Hedley Griffiths Consultant of: AbbVie, Gilead, Janssen, Novartis, Peter Peichl: None declared, Bettina Bannert: None declared, Adrian Forster: None declared, Melanie Chartier Shareholder of: Bristol Myers Squibb, Employee of: Bristol Myers Squibb, Yedid Elbez Consultant of: Bristol Myers Squibb, Christiane Rauch Shareholder of: Bristol Myers Squibb, Employee of: Bristol Myers Squibb, Karissa Lozenski Shareholder of: Bristol Myers Squibb, Employee of: Bristol Myers Squibb, Vadim Khaychuk Shareholder of: Bristol Myers Squibb, Employee of: Bristol Myers Squibb

AB0207 ANALYSIS OF ABATACEPT TREATMENT RETENTION AND EFFICACY ACCORDING TO DISEASE DURATION AND TREATMENT LINE IN A REAL-WORLD SETTING

Background:

Longer disease duration and greater number of prior DMARDs have been associated with lower treatment efficacy in patients with RA.1 Abatacept is a biologic (b)DMARD for treatment of moderate-to-severe RA and is available in SC formulation, which may offer convenience benefits with efficacy similar to IV administration.2 ASCORE (Abatacept SubCutaneOus in Routine Clinical PracticE; NCT02090556) was a 2-year, observational, prospective, multicentre study of SC abatacept for treatment of RA in routine clinical practice.3

Objectives:

This post hoc analysis was conducted to determine if retention and efficacy of abatacept were impacted by disease duration and/or treatment line.

Methods:

Eligible patients, aged ≥18 years, with active moderate-to-severe RA (ACR/EULAR 2010 criteria) who were IV abatacept-naive and initiated SC abatacept 125 mg once weekly, were enrolled into two cohorts: bDMARD-naive patients and those with ≥1 prior bDMARD treatment failure. This post hoc analysis evaluated abatacept retention using Kaplan-Meier estimates, as well as disease activity scores (DAS28 [ESR]), CDAI and SDAI in patients with disease duration of ≤2, 3–5, 6–10 or >10 years, and in patients taking abatacept as first-line or ≥ second-line treatment.

Results:

Table 1 shows baseline (BL) characteristics. Mean age increased with disease duration; other characteristics were comparable across groups. Retention proportions (95% CIs) at Month 24 were 0.50 (0.4, 0.5), 0.47 (0.4, 0.5), 0.51 (0.5, 0.5) and 0.46 (0.4, 0.5) in the ≤2, 3–5, 6–10 and >10 years’ duration groups, respectively. Proportion of patients (95% CI) with ≤2 years’ duration retaining treatment at Month 24 were 0.51 (0.4, 0.6) among those using abatacept as first-line treatment and 0.44 (0.3, 0.6) among those using abatacept as a ≥ second-line treatment (Figure 1). Proportions (95% CI) at Month 24 were 0.51 (0.5, 0.6), 0.57 (0.5, 0.6) and 0.52 (0.5, 0.6) in first-line patients and 0.43 (0.4, 0.5), 0.48 (0.4, 0.5) and 0.44 (0.4, 0.5) in ≥ second-line patients in the 3–5, 6–10 and >10 years’ duration groups, respectively. Mean (SE) changes from BL in DAS28 (ESR) at Month 24 were –2.12 (0.205), –1.86 (0.151), –2.07 (0.140) and –2.05 (0.115) in the ≤2, 3–5, 6–10 and >10 years’ duration groups, respectively; respective mean (SE) changes in CDAI were –18.74 (1.604), –15.60 (1.099), –18.50 (1.038) and –17.68 (0.850); and respective mean (SE) changes in SDAI were –19.10 (1.873), –15.72 (1.345), –19.54 (1.103) and –17.07 (0.939).

Conclusion:

In this post hoc analysis of the real-world ASCORE trial, patients with RA receiving abatacept in clinical practice as first-line therapy had better retention versus those receiving it as a ≥ second-line treatment, regardless of disease duration at BL. Retention rates were similar across disease duration subgroups. Improvements in disease activity were seen in all duration subgroups, without consistently greater or lesser improvement seen with longer disease duration.

References:

[1]Aletaha D, et al. Ann Rheum Dis 2019;78:1609–1615.

[2]Genovese MC, et al. Arthritis Rheumatol 2011;63:2854–2864.

[3]Alten R, et al. Ann Rheum Dis 2019;78(suppl 2):A1639.

Table 1.

BL characteristics (n=2872)

RA disease duration, years≤2(n=338)3–5(n=655)6–10(n=686)>10(n=1193)Age, years n3386556861193 Mean (SD)55.2 (12.8)55.6 (12.7)56.9 (13.0)59.9 (12.2)Weight, kg n3276296651150 Mean (SD)75.3 (18.1)76.4 (19.0)74.7 (17.4)72.9 (16.0)DAS28 (ESR) n247439441743 Mean (SD)5.2 (1.3)4.9 (1.3)5 (1.2)5.1 (1.3)DAS28 (CRP) n267460467799 Mean (SD)4.7 (1.2)4.6 (1.2)4.7 (1.1)4.7 (1.2)CDAI n269477474805 Mean (SD)26.9 (12.7)25.3 (12.2)26.8 (12.4)26.6 (12.2)SDAI n255448445749 Mean (SD)28.3 (13.3)26.8 (12.9)27.9 (12.6)28.0 (12.7)RF status, n (%) RF+159 (47.0)342 (52.2)345 (50.3)597 (50.0) RF–103 (30.5)152 (23.2)158 (23.0)215 (18.0)Anti-CCP status, n (%) Anti-CCP+165 (48.8)332 (50.7)333 (48.5)516 (43.3) Anti-CCP–89 (26.3)126 (19.2)137 (20.0)175 (14.7)

Patients with missing duration of disease are excluded.

CCP=cyclic citrullinated peptide.

Acknowledgements:

Professional medical writing and editorial assistance was provided by Rob Coover, MPH, at Caudex and was funded by Bristol Myers Squibb. This study was funded by Bristol Myers Squibb.

Disclosure of Interests:

Rieke Alten Speakers bureau: AbbVie, Bristol Myers Squibb, Gilead, Janssen, Lilly, Pfizer, Consultant of: AbbVie, Bristol Myers Squibb, Gilead, Janssen, Lilly, Pfizer, Grant/research support from: AbbVie, Bristol Myers Squibb, Gilead, Janssen, Lilly, Pfizer, Xavier Mariette Consultant of: Bristol Myers Squibb, Galapagos, Gilead, GlaxoSmithKline, Janssen, Pfizer, UCB, Rene-Marc Flipo Speakers bureau: AbbVie, Bristol Myers Squibb, Janssen, Lilly, Medac, Merck Sharp & Dohme, Novartis, Pfizer, Roche-Chugai, Grant/research support from: Amgen, Janssen, Novartis, Pfizer, Roberto Caporali Speakers bureau: AbbVie, Amgen, Bristol Myers Squibb, Celltrion, Fresenius Kabi, Galapagos, Gilead, Lilly, Merck Sharp & Dohme, Pfizer, Roche, Samsung Bioepis, Sanofi, UCB, Consultant of: Galapagos, Gilead, Janssen, Lilly, Merck Sharp & Dohme, Maya H Buch Speakers bureau: AbbVie, Consultant of: AbbVie, Eli Lilly, Gilead, Merck Serono, Pfizer, Roche, Sanofi, Grant/research support from: Gilead, Pfizer, Roche, UCB, Yusuf Patel: None declared, Raimón Sanmartí Speakers bureau: AbbVie, Bristol Myers Squibb, Gebro, Janssen, Lilly, Merck Sharp & Dohme, Pfizer, Roche, Sanofi, Consultant of: AbbVie, Bristol Myers Squibb, Gebro, Lilly, Merck Sharp & Dohme, Pfizer, Roche, Sanofi, Grant/research support from: Bristol Myers Squibb, Merck Sharp & Dohme, Pfizer, Sara Marsal Speakers bureau: Bristol Myers Squibb, Celgene, Pfizer, Roche, Sanofi, UCB, Consultant of: AbbVie, Bristol Myers Squibb, Celgene, Galapagos, Merck Sharp & Dohme, Pfizer, Roche, Sanofi, UCB, Grant/research support from: AbbVie, Bristol Myers Squibb, Celgene, Janssen, Merck Sharp & Dohme, Novartis, Pfizer, Roche, Sanofi, UCB, M.T. Nurmohamed Speakers bureau: AbbVie, Bristol Myers Squibb, Eli Lilly, Roche, Sanofi, Consultant of: AbbVie, Celgene, Celltrion, Eli Lilly, Janssen, Grant/research support from: AbbVie, Bristol Myers Squibb, Celgene, Eli Lilly, Janssen, Merck Sharp & Dohme, Mundipharma, Novartis, Pfizer, Roche, Sanofi, Hedley Griffiths Consultant of: AbbVie, Gilead, Janssen, Novartis, Peter Peichl: None declared, Bettina Bannert: None declared, Adrian Forster: None declared, Melanie Chartier Shareholder of: Bristol Myers Squibb, Employee of: Bristol Myers Squibb, Yedid Elbez Consultant of: Bristol Myers Squibb, Christiane Rauch Shareholder of: Bristol Myers Squibb, Employee of: Bristol Myers Squibb, Vadim Khaychuk Shareholder of: Bristol Myers Squibb, Employee of: Bristol Myers Squibb, Karissa Lozenski Shareholder of: Bristol Myers Squibb, Employee of: Bristol Myers Squibb

Glutathione transferases P1/P2 regulate the timing of signaling pathway activations and cell cycle progression during mouse liver regeneration

Glutathione transferases (GST) are phase II enzymes catalyzing the detoxification of endogenous noxious compounds and xenobiotics. They also regulate phosphorylation activities of MAPKinases in a catalytic-independent manner. Previous studies have demonstrated the regulation of JNK-dependent pathway by GSTP1/2. Considering the crucial role of JNK in the early steps of the hepatocyte cell cycle, we sought to determine whether GSTP1/2 were essential for hepatocyte proliferation following partial hepatectomy (PH). Using a conventional double knockout mouse model for the Gstp1 and Gstp2 genes, we found that the lack of GSTP1/P2 reduced the rate of DNA replication and mitotic index during the first wave of hepatocyte proliferation. The lowered proliferation was associated with the decrease in TNFalpha and IL-6 plasma concentrations, reduced hepatic HGF expression and delayed and/or altered activation of STAT3, JNK and ERK1/2 signaling pathways. In addition, the expression and/or activation of cell cycle regulators such as Cyclin D1, CDK4, E2F1 and MCM7 was postponed demonstrating that the absence of GSTP1/2 delayed the entry into and progression through the G1 phase of the cell cycle and impaired the synchrony of proliferation in hepatocytes following PH. Furthermore, while JNK and its downstream targets c-Jun and ATF2 were activated during the early steps of the liver regeneration in wild-type animals, the constitutively active JNK found in the quiescent liver of Gstp1/2 knockout mice underwent a decrease in its activity after PH. Transient induction of antioxidant enzymes and nitric oxide synthase were also delayed or repressed during the regenerative response. Altogether our results demonstrate that GSTP1/2 are a critical regulators of hepatocyte proliferation in the initial phases of liver regeneration.

Cerebral cell renewal in adult mice controls the onset of obesity

The hypothalamus plays a crucial role in the control of the energy balance and also retains neurogenic potential into adulthood. Recent studies have reported the severe alteration of the cell turn-over in the hypothalamus of obese animals and it has been proposed that a neurogenic deficiency in the hypothalamus could be involved in the development of obesity. To explore this possibility, we examined hypothalamic cell renewal during the homeostatic response to dietary fat in mice, i.e., at the onset of diet-induced obesity. We found that switching to high-fat diet (HFD) accelerated cell renewal in the hypothalamus through a local, rapid and transient increase in cell proliferation, peaking three days after introducing the HFD. Blocking HFD-induced cell proliferation by central delivery of an antimitotic drug prevented the food intake normalization observed after HFD introduction and accelerated the onset of obesity. This result showed that HFD-induced dividing brain cells supported an adaptive anorectic function. In addition, we found that the percentage of newly generated neurons adopting a POMC-phenotype in the arcuate nucleus was increased by HFD. This observation suggested that the maturation of neurons in feeding circuits was nutritionally regulated to adjust future energy intake. Taken together, these results showed that adult cerebral cell renewal was remarkably responsive to nutritional conditions. This constituted a physiological trait required to prevent severe weight gain under HFD. Hence this report highlighted the amazing plasticity of feeding circuits and brought new insights into our understanding of the nutritional regulation of the energy balance.

Endotoxin transiently inhibits protein synthesis through Akt and MAPK mediating pathways in C2C12 myotubes

In this study, the effect of lipopolysaccharide (LPS) on protein synthesis (PS) and intracellular signaling factors that regulate it have been investigated in C2C12 murine-derived myotubes. In particular, the role of Akt/mammalian target of rapamycin (mTOR) and the mitogen-activated protein kinases (MAPKs) [p38 and extracelluar regulated protein kinase (ERK1/2)] have been examined. The direct effect of LPS on PS was measured at 3 and 18 h. LPS significantly decreased PS at 3 h but not at the 18-h time point. This effect was preceded by decreased Akt phosphorylation at 5 and 30 min after LPS administration. The mTOR phosphorylation exhibited a long time dose-dependent increase at all the time points. Similarly, the activity-related phosphorylation of p38 and ERK1/2 significantly increased in a time- and dose-dependent manner at all the time points. Polymyxin B abolished the LPS-induced decrease in PS rate. The phosphatidylinositol 3-kinase inhibitor LY-0294002 in combination with LPS significantly decreased the rate of PS by 81% and alone by 66%, respectively, for the 3- and 18-h time points, whereas p38 and ERK inhibitors in combination with LPS significantly decreased the rate PS rate at the 18-h time point by 41% and 59%, respectively, compared with control cells. In conclusion, LPS alone transiently decreased the rate of PS by 50% at 3 h; this effect is most likely mediated via the Toll-like receptor 4 (TLR4)-Akt/mTOR pathway, and both p38 and ERK when inhibited in the presence of LPS at 3 h have a similar effect in preventing the LPS-induced reduction in PS.

Cyclosporin-A inhibits stretch-induced changes in myosin heavy chain expression in C2C12 skeletal muscle cells

Studies in vivo, have shown that passive stretch of skeletal muscle induces changes in contractile protein expression. In the present study the effects of passive stretch upon myosin heavy chain (MyHC) expression were examined in C2C12 cell myotubes. Passive stretch induced an upregulation of adult fast and slow MyHCs, which was prevented by cyclosporin A (CsA), an inhibitor of calcineurin. Calcineurin has been shown to act via the dephosphorylation of NFAT and MEF2 transcriptional factors. In this study no significant change in the phosphorylation state of these factors was observed. In contrast stretch induced an alteration in the levels of the myogenic regulatory factors (MRFs) MyoD, myogenin and myf5. The modulation in the level of these MRFs was also inhibited by CsA. These data indicate that changes in muscle phenotype in C2C12 can be modulated by passive stretch and some of these changes are calcineurin dependent.

Einweisung von Nicht-Schlaganfallpatienten auf eine Stroke Unit

BACKGROUND AND OBJECTIVE

Stroke care in Germany has substantially improved during the last decade. One column of modern stroke care is the institution of stroke unit which allows rapid diagnosis and treatment. The aspect of admission of nonstroke patients to a stroke unit is poorly evaluated. The aim of this study is to evaluate the number of patients who are admitted to a national stroke unit but do not suffer from stroke. Furthermore, we related the proportion of nonstroke referrals to the different referral modes.

PATIENT AND METHODS

Observational study recording all suspected stroke referrals with regard to final diagnosis and type of referral during a 12-month period (1.8.2002-31.7.2003).

RESULTS

462 patients were admitted by 4 routes: 74 by paramedics or by self-presentation, 138 by emergency physicians, 144 by primary care doctors, and 106 were transferred from other hospitals. 88 patients (19 %) finally revealed no acute stroke. The most common nonstroke diagnoses were seizure (20 %), dissociative disorders (14 %), cranial nerve disorders (11 %), hypoglycaemia (8 %) and transient global amnesia (7 %). There was no significant difference among the proportion of nonstroke patients referred by ambulance paramedics and self-presentation (15 %), emergency physicians (21 %), primary care doctors (15 %) and interhospital transfer (24 %) [p = 0.222, X (2)-test according to Pearson].

CONCLUSION

Due to the fact that a number of clinical neurological conditions mimic acute stroke, misdiagnosis of stroke is common. We advocate that all stroke patients are seen early in the course of the disease by a neurologist. An alternative could be that in stroke units of internal medicine hospitals patients are seen by a consulting neurologist. Alternatively, telemedicine might be used and the neurologist on duty of a neurological stroke unit could be consulted.

Comparison of peak and trough level monitoring of cyclosporine treatment using two modern cyclosporine preparations

AIMS

Determination of the peak cyclosporine blood level instead of the trough level promises to represent an improvement in cyclosporine therapy monitoring due to better correlation with the AUC. In kidney transplant recipients we investigated whether this conclusion applies also to a new dispersion formulation of cyclosporine (Cicloral).

PATIENTS

42 stable kidney transplant recipients were converted from Sandimmun Neoral (NEO) to Cicloral (CIC) in a 1:1 dose relation.

METHODS

On the last day of NEO administration and 14 days after conversion to CIC a full 12 h cyclosporine AUC was performed using blood samples obtained prior to and at serial times after dosing. The correlations between cyclosporine levels at these time points and the AUC were determined for NEO and CIC. For each measurement, a predicted AUC was calculated by regression analysis. The prediction error for each sampling time was calculated separately for NEO and CIC.

RESULTS

The cyclosporine trough levels showed the poorest correlation with AUC for both preparations (NEO: r = 0.187 vs CIC: r = 0.554). The best correlation was observed for samples obtained at three hours after intake of either CIC (r = 0.807) or NEO (r = 0.611). The number of 2 hours measurements that lead to an unacceptable estimate from the real AUC was somewhat lower for CIC (8/40 vs 11/41 with NEO).

CONCLUSIONS

Two- or three-hour cyclosporine level monitoring with the newer cyclosporine preparation Cicloral has at least the same precision as that of the original Neoral(R). In this study, the newer preparation even showed a tendency towards superior monitoring properties.

Alfuzosin, an alpha1-adrenoceptor antagonist for the treatment of benign prostatic hyperplasia: once daily versus 3 times daily dosing in healthy subjects

OBJECTIVE

A new patented prolonged release formulation of the alpha1-adrenoceptor antagonist alfuzosin has been developed for once-daily (OD) administration in benign prostatic hyperplasia (BPH). This study was designed to compare 2 dose regimens: 10 mg OD alfuzosin and 2.5 mg TID alfuzosin at steady state.

METHODS

In an open, randomized crossover study with a 9-day washout between treatments, 18 healthy male subjects (50 - 65 years) received OD or TID alfuzosin tablets orally over 5 days. Both formulations were administered according to the schedule recommended for therapeutic use: OD was administered 5 min after the evening meal, TID was administered in the evening, then in the morning and at noon (30 min before meals). On the fifth day, plasma concentrations were quantitated by HPLC with spectrofluorometric detection.

RESULTS

The following pharmacokinetic parameters refer to the geometric mean values for both formulations. Mean Cmax value of 10 mg OD alfuzosin was 15.8 ng/ml at a median t(max) of 9.0 h; Cmax was higher and reached earlier from 2.5 mg alfuzosin TID: 19.3 ng/ml, 19.7 ng/ml and 20.3 at 1.0 hour after each dosing, respectively. Mean AUC(0-24) values after OD and TID were 228.3 and 226.0 ng x h/ml, respectively. Based on AUC(0-24) values corrected by the administered daily dose, the relative bioavailability of alfuzosin OD was 75.7% with a 90% confidence interval of 68.0 - 84.3%. Non-corrected AUC(0-24) values were bioequivalent with a ratio estimate of 101.0% and a 90% confidence interval of 90.7 - 112.5%. The higher daily dose compensated for the loss of bioavailability observed with the OD formulation. Mean t1/2z value was longer for the OD (8.9 h) than the TID formulation (6.9 h). Variability between individuals was similar for the 2 formulations. Both dose regimens were well tolerated.

CONCLUSIONS

Alfuzosin 10 mg once-daily provides a suitable pharmacokinetic profile for a once-daily administration, equivalent bioavailability between the 2 dosage regimens and a good safety profile justify the use of alfuzosin 10 mg in patients with BPH.

Effect of polymorphism in the human glutathione S-transferase A1 promoter on hepatic GSTA1 and GSTA2 expression

The patterns of expression of glutathione S-transferases A1 and A2 in human liver (hGSTA1 and hGSTA2, respectively) are highly variable, notably in the ratio of hGSTA1/hGSTA2. We investigated if this variation had a genetic basis by sequencing the proximal promoters (-721 to -1 nucleotides) of hGSTA1 and hGSTA2, using 55 samples of human liver that exemplified the variability of hGSTA1 and hGSTA2 expression. Variants were found in the hGSTA1 gene: -631T or G, -567T, -69C, -52G, designated as hGSTA1*A; and -631G, -567G, -69T, -52A, designated as hGSTA1*B. Genotyping for the substitution -69C > T by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP), showed that the polymorphism was widespread in Caucasians, African-Americans and Hispanics, and that it appeared to conform to allelic variation. Constructs consisting of the proximal promoters of hGSTA1*A, hGSTA1*B or hGSTA2, with luciferase as a reporter gene, showed differential expression when transfected into HepG2 cells: hGSTA1*A approximately hGSTA2 > hGSTA1*B. Similarly, mean levels of hGSTA1 protein expression in liver cytosols decreased significantly according to genotype: hGSTA1*A > hGSTA1-heterozygous > hGSTA1*B. Conversely, mean hGSTA2 expression increased according to the same order of hGSTA1 genotype. Consequently, the ratio of GSTA1/GSTA2 was highly hGSTA1 allele-specific. Because the polymorphism in hGSTA1 correlates with hGSTA1 and hGSTA2 expression in liver, and hGSTA1-1 and hGSTA2-2 exhibit differential catalysis of the detoxification of carcinogen metabolites and chemotherapeutics, the polymorphism is expected to be of significance for individual risk of cancer or individual response to chemotherapeutic agents.

Clathrin-dependent and clathrin-independent endocytosis are differentially sensitive to insertion of poly (ethylene glycol)-derivatized cholesterol in the plasma membrane

We examined the effect of a cholesterol derivative, poly (ethylene glycol) cholesteryl ether on the structure/function of clathrin-coated pits and caveolae. Addition of the compound to cultured cells induced progressive smoothening of the surface. Markedly, when the incorporated amount exceeded 10% equivalent of the surface area, fluid pinocytosis, but not endocytosis of transferrin, became inhibited in K562 cells. In A431 cells, both clathrin-independent fluid phase uptake and the internalization of fluorescent cholera-toxin B through caveolae were inhibited with concomitant flattening of caveolae. In contrast, clathrin-mediated internalization of transferrin was not affected until the incorporated poly (ethylene glycol) cholesteryl ether exceeded 20% equivalent of the plasma membrane surface area, at which point opened clathrin-coated pits accumulated. The cells were ruptured upon further addition of poly (ethylene glycol) cholesteryl ether. We propose that the primary reason for the differential effect of poly (ethylene glycol) cholesteryl ether is that the bulk membrane phase and caveolae are both more elastic than the rigid clathrin-coated pits. We analyzed the results with the current mechanical model (Rauch and Farge, Biophys J 2000;78:3036-3047) and suggest here that the functional clathrin-lattice is much stiffer than typical phospholipid bilayers.

Endocytosis switch controlled by transmembrane osmotic pressure and phospholipid number asymmetry

The dynamics of endocytosis in living K562 cells was investigated after the osmotic pressure of the external medium was decreased and the transmembrane phospholipid number asymmetry was increased. When the external pressure was decreased by a factor of 0.54, a sudden inhibition of endocytosis was observed. Under these conditions, the endocytosis suddenly recovered after the phospholipid number asymmetry was increased. The phospholipid asymmetry was generated by the addition of exogenous phosphatidylserine, which is translocated by the endogenous flippase activity to the inner layer of the membrane. The recovery of endocytosis is thus consistent with the view that the phospholipid number asymmetry can act as a budding force for endocytosis. Moreover, we quantitatively predict both the inhibition and recovery of endocytosis as first-order phase transitions, using a general model that assumes the existence of a transmembrane surface tension asymmetry as the budding driving force. In this model, the tension asymmetry is considered to be elastically generated by the activity of phospholipid pumping. We finally propose that cells may trigger genetic transcription responses after the internalization of cytokine-receptor complexes, which could be controlled by variations in the cytosolic or external pressure.

Pharmacokinetics of new testosterone transdermal therapeutic systems in gonadotropin-releasing hormone antagonist-suppressed normal men

In a phase I single-center, open, randomized pilot study with a three-way cross-over design the pharmacokinetics of three testosterone-containing transdermal therapeutic systems were evaluated in healthy male volunteers. Testosterone TTS HEXAL type 1 and 2 are nonscrotal membrane patches differing in the kind of adhesive used. 6 subjects were treated with low dose Testosterone TTS type 1, high dose Testosterone TTS type 1 and low dose Testosterone TTS type 2. To eliminate the influence of endogenous serum testosterone, the endogenous testosterone secretion was suppressed by the GnRH antagonist cetrorelix. In all subjects under GnRH antagonist treatment a marked suppression of LH, FSH, testosterone, DHT and estradiol was observed. Physiologic testosterone levels were achieved during the 24-hour-application period. Maximal serum levels were reached after 4 hours with both TTS systems. Both systems appear suited for further testing because both enable a physiological circadian profile to be achieved. GnRH-antagonist pretreatment is a useful model to evaluate the effect of exogenous testosterone in clinical studies, when, due to fluctuations in endogenous hormone levels, an estimation of the proportion of exogenous steroid is not possible.

Genomic organization, 5'-flanking region and chromosomal localization of the human glutathione transferase A4 gene

We have isolated and characterized a human glutathione transferase A4 (hGSTA4) subunit gene from a yeast artificial chromosome containing several other glutathione transferase alpha genes and pseudogenes. The homodimeric protein hGSTA4-4, is involved in the detoxification of 4-hydroxynonenal and other reactive electrophiles produced by oxidative metabolism, and may have a significant role in protecting intracellular components from oxidative damage. The hGSTA4 gene spans nearly 18 kb, contains seven exons, maps onto chromosome 6p12, and lies in close proximity to the 7SK small nuclear RNA gene in a head-to-tail orientation. The intron/exon borders conform to the standard rules, an open reading frame is present beginning at position 154 in exon 2, and the stop codon is at position 822 in exon 7. The transcription initiation site has been determined by primer extension analysis and is located 135 bp upstream of intron 1. Isolation and sequencing of the hGSTA4 gene 5'-flanking region revealed it to be devoid of TATA or CCAAT boxes but it does contain an initiator element overlapping the transcription start site, a GC box and putative binding sites for transcription factors AP1, STAT, GATA1 and NF-kappaB. Reverse transcription-PCR analysis revealed that hGSTA4 mRNA was present in all the tissues tested, although in low amounts, suggesting that this subunit may be ubiquitously expressed.

A poxvirus-encoded semaphorin induces cytokine production from monocytes and binds to a novel cellular semaphorin receptor, VESPR

The vaccinia virus A39R protein is a member of the semaphorin family. A39R.Fc protein was used to affinity purify an A39R receptor from a human B cell line. Tandem mass spectrometry of receptor peptides yielded partial amino acid sequences that allowed the identification of corresponding cDNA clones. Sequence analysis of this receptor indicated that it is a novel member of the plexin family and identified a semaphorin-like domain within this family, thus suggesting an evolutionary relationship between receptor and ligand. A39R up-regulated ICAM-1 on, and induced cytokine production from, human monocytes. These data, then, describe a receptor for an immunologically active semaphorin and suggest that it may serve as a prototype for other plexin-semaphorin binding pairs.

[Genetics and society: ethic and legal implications]

Medical genetics, recently individualised as a full medical specialty, evidences new problems issued from its natural and historical developments. Genetics counselling, prenatal and predictive diagnosis may be considered as a real progress when applied in the strictly medical and individual fields. When extended to the whole community to answer collective choices, these technologies can turn into eugenic and standardizing practices. Regarding the public health and the economic necessity it could be inviting to overpass the essential values on which are founded our humanity. In that context laws are required to defend the best use for human being several practices, but only after an ethical debate in which everyone should participate.

Evidence of thyrotropin-releasing hormone (TRH) gene expression in rat anterior pituitaries and modulation by estrogens of TRH-like immunoreactivity and TRH-elongated peptide contents

TRH gene expression in the anterior pituitary has previously been reported in the human in vivo and in the rat in vitro. Until now, modulation of this synthesis with glucocorticoids and thyroid hormones has been observed in rats. The present study demonstrates for the first time that the TRH gene is also expressed, in vivo, in the rat anterior pituitary and that anterior pituitary TRH-like immunoreactivity (TRH-LI) and elongated forms of the immediate TRH progenitor sequence (TRH-elongated peptide) contents are also modulated by estrogens (E2). To investigate the presence of proTRH mRNA in the rat anterior pituitary, total RNA was reverse transcribed (RT) and the RT products were then amplified by PCR. Treatments with E2 were performed on intact and ovariectomized (OVX) rats for 2 months. TRH-LI was measured by RIA with an antibody which did not recognize the TRH-like peptide. pGlu-Glu-Pro-NH2 (< EEP-NH2) (cross-reactivity < 0.1%) and was characterized further as TRH-LI by HPLC. TRH-elongated peptides were measured by EIA and characterized by Sephadex G-50 chromatography and immunoblotting (molecular mass 25-35 kDa). The plasma prolactin levels and the pituitary sizes were increased by E2 treatment in both intact and OVX rats. Anterior pituitary TRH-LI increased in intact E2-treated rats compared with intact rats (82.7 +/- 19.0 versus 39.6 +/- 3.6 fmol/mg protein; means +/- S.E.M.; P < 0.001). This increase was greater when E2 was administered to OVX rats (599.0 +/- 98.4 after E2 treatment versus 58.6 +/- 3.6 fmol/mg protein: P < 0.001). In intact rats, anterior pituitary TRH-elongated peptide contents were not modified by E2 treatment while they were significantly decreased in OVX E2-treated rats (144.6 +/- 8.8 versus 223.7 +/- 9.5 fmol/mg protein; P < 0.001). These results demonstrate TRH gene expression in the rat anterior pituitary in vivo and suggest that E2 treatment is responsible for an increase in anterior pituitary TRH-LI, together with a decrease in TRH-elongated peptide contents.

The human homologue of rat NG2, a chondroitin sulfate proteoglycan, is not expressed on the cell surface of normal hematopoietic cells but is expressed by acute myeloid leukemia blasts from poor-prognosis patients with abnormalities of chromosome band 11q23

In our efforts to produce monoclonal antibodies that recognize cell-surface antigens expressed by hematopoietic precursor and stromal cells, we generated a monoclonal antibody, 7.1, which recognizes a 220- to 240-kD cell-surface protein whose N-terminal amino acid sequence is identical to the rat NG2 chondroitin sulfate proteoglycan molecule. This chondroitin sulfate proteoglycan, previously reported to be expressed by human melanoma cells, was not found to be expressed by normal hematopoietic cells, nor was it expressed on the cell surface of cell lines of hematopoietic origin including cell lines with 11q23 abnormalities. It was found on the cell surface of acute myeloid leukemia (AML) blasts and cell lines derived from nonhematopoietic tissues. Samples of leukemic marrow from 166 children with AML enrolled on Childrens Cancer Group protocol 213 were evaluated for cell-surface expression of this proteoglycan molecule. In 18 of 166 (11%) patient samples, greater than 25% of leukemic blasts expressed the NG2 molecule. These 18 patients had a poorer outcome with respect to survival (P = .002) and event-free survival (P = .035) with an actuarial survival at 4 years of 16.7%. Blast cell expression of the NG2 molecule was strongly associated with French-American-British M5 morphology (P < .0001) and abnormalities in chromosome band 11q23, site of the MLL gene. These results show that the NG2 molecule is expressed by malignant hematopoietic cells that have abnormalities in chromosome band 11q23, suggesting that antibody 7.1 may be useful in the rapid identification of this group of poor-prognosis patients.

Identification and characterization of a new member of the TNF family that induces apoptosis

A novel tumor necrosis factor (TNF) family member has been cloned and characterized. This protein, designated TNF-related apoptosis-inducing ligand (TRAIL), consists of 281 and 291 aa in the human and murine forms, respectively, which share 65% aa identity. TRAIL is a type II membrane protein, whose C-terminal extracellular domain shows clear homology to other TNF family members. TRAIL transcripts are detected in a variety of human tissues, most predominantly in spleen, lung, and prostate. The TRAIL gene is located on chromosome 3 at position 3q26, which is not close to any other known TNF ligand family members. Both full-length cell surface expressed TRAIL and picomolar concentrations of soluble TRAIL rapidly induce apoptosis in a wide variety of transformed cell lines of diverse origin.

Characterization and localization of an immunoreactive growth hormone-releasing hormone precursor form in normal and tumoral human anterior pituitaries

Arguments favor an in situ synthesis of GH-releasing hormone (GHRH) in the normal and tumoral human anterior pituitary. These tissues may express human (h) GHRH messenger RNA, contain hGHRH-(1-44)-NH2, and secrete in vitro an immunoreactive form (ir-form) of the peptide. Here, we characterize and localize the precursor of hGHRH in human anterior pituitary tissues using RIAs specific for the C-terminus or the midportion of hGHRH-(1-44)-NH2, size-exclusion chromatography, HPLC, Western blotting, and immunocytochemistry. The anterior pituitary ir-forms were compared to those found in hypothalamus, posterior pituitary, and GHRH-secreting endocrine pancreatic tumors. Three ir-forms of hGHRH with mol wt of 30-45, and 5 kilodaltons (kDa) were detected. The 30- to 45-kDa ir-form was very likely to consist of hGHRH bound to proteins. The 5-kDa ir-form represented mature forms of hGHRH. It was the major form in tissues actively synthesizing and/or secreting hGHRH. Nontumoral anterior pituitaries contained significant amounts of mature hGHRH. The 10-kDa form was identified as a hGHRH precursor ir-form. In addition to its expected presence in the hypothalamus and GHRH-secreting tumors, normal and tumoral human anterior pituitaries contained an identical ir-form of the hGHRH precursor. Cells immunoreactive for the hGHRH precursor were observed in pituitary adenomas. Evidence for precursor and mature ir-forms of hGHRH in anterior pituitary tissues provides conclusive arguments for the endogenous synthesis of the neuropeptide.

Presence of somatostatin receptors negatively coupled to adenylate cyclase in ectopic growth hormone-releasing hormone- and alpha-subunit-secreting tumors from acromegalic patients responsive to octreotide

The functional study of SRIH receptors was performed in ectopic GHRH-secreting tumors from two patients with acromegaly; patient 1 presented with multiple endocrine neoplasia type 1 with GHRH- and insulin-secreting pancreatic tumors, and patient 2 presented with a multihormone-secreting carcinoid tumor (including GHRH and alpha-subunit secretion, as demonstrated by clinical and immunohistochemical studies). In both cases, plasma GH levels were responsive to octreotide. In patient 2, plasma GHRH and alpha-subunit levels were responsive to octreotide. In vitro perifusion studies of a tumor fragment from patient 1 also showed inhibition of GHRH secretion by SRIH. A high density of specific SRIH-binding sites was visualized by autoradiography in GHRH tumors from both patients. SRIH specific binding was much higher in the GHRH tumors (6.6-8.4 fmol/surface unit) than in the insulinoma (1.9 fmol/surface unit). The binding inhibition constant (IC50) was in the nanomolar range (0.9-3 nmol/L) in the GHRH tumors. SRIH-14 inhibited forskolin-stimulated adenylate cyclase in the GHRH tumors from both patients, but not in the insulinoma. The functional SRIH receptors negatively coupled to adenylate cyclase present in ectopic GHRH-secreting tumors mediate the inhibitory effect of octreotide on GHRH secretion and on previously underrecognized ectopic alpha-subunit secretion from carcinoid tumors.

Effect of the slow-release formulation of somatuline (BIM 23014) on estrogen-induced hyperprolactinemia and lactotroph hyperplasia in the female rat

Somatuline, in common with other SRIH analogues, exerts antiproliferative and antisecretory activities on various tumors. Our purpose was to test the effectiveness of a slow-release formulation of somatuline on lactotroph hyperplasia and PRL hypersecretion induced by estrogens (17 beta E2) in rats. Female rats were primed with 17 beta E2 for 6 weeks before receiving somatuline (2 mg/kg) intramuscular injections every 10 days for one month. The mean anterior pituitary weight was 11.22 +/- 0.32 mg (mean +/- SEM) in non-estrogenized rats, 29.62 +/- 1.63 mg in 17 beta E2-primed rats and 23.58 +/- 1.26 mg in 17 beta E2-primed somatuline-treated rats. Mean plasma PRL level was 5.63 +/- 0.97 ng/ml, 182.37 +/- 27.55 ng/ml and 113.89 +/- 15.07 ng/ml in the same groups respectively. Thus, the 17 beta E2-induced pituitary enlargement and hyperprolactinemia were 20% and 38% lower respectively when animals were treated with somatuline during the last month of estrogenization. The 17 beta E2-induced increase in PRL cell density was also reduced by somatuline treatment. We conclude that the slow-release formulation of somatuline impedes 17 beta E2-induced hyperprolactinemia and pituitary enlargement concomittantly, at least in part by acting on lactotroph proliferation.

Cloning of a T cell growth factor that interacts with the beta chain of the interleukin-2 receptor

A cytokine was identified that stimulated the proliferation of T lymphocytes, and a complementary DNA clone encoding this new T cell growth factor was isolated. The cytokine, designated interleukin-15 (IL-15), is produced by a wide variety of cells and tissues and shares many biological properties with IL-2. Monoclonal antibodies to the beta chain of the IL-2 receptor inhibited the biological activity of IL-15, and IL-15 competed for binding with IL-2, indicating that IL-15 uses components of the IL-2 receptor.

Specific binding of progesterone receptor to progesterone-responsive elements does not require prior dimerization

Steroid-hormone receptors undergo, prior to binding to DNA, a hormone-dependent dimerization. It is generally accepted that this dimerization is indispensable for the high-affinity binding of hormone receptor to hormone-responsive elements. Using a progesterone-receptor mutant with the complete steroid-binding domain deleted (positions 663-930), with or without the epitope required for binding the monoclonal antibody Let 126, we have shown that this receptor species was unable to undergo dimerization in solution. However, this mutant retained a high affinity (60-70% of the affinity of the wild-type receptor) for the progesterone-responsive elements of the mouse-mammary-tumor-virus long-terminal-repeat promoter and for a consensus palindromic progesterone-responsive element, as measured by both DNase-I protection experiments and gel-shift experiments. This mutant also increased gene transcription. Thus, at least in the case of the progesterone receptor, prior dimerization is dispensable for receptor binding to regulatory DNA elements and for subsequent transcription activation.

In two genes, synergism of steroid hormone action is not mediated by cooperative binding of receptors to adjacent sites

Synergistic action of multiple steroid hormone response elements (HREs) has been proposed to be due to cooperative binding of receptors. We have studied the cooperativity of steroid hormone receptor binding to synergistic HREs in two natural genes. In the mouse mammary tumor virus long terminal repeat that contains four progesterone receptor binding sites, no cooperativity in receptor binding was observed between the single distal and the three proximal sites whereas a low level of cooperativity in receptor binding (about 2-fold) was found between the three proximal sites. This contrasted with the very strong synergism of these four HREs in stimulation of transcription. In the chicken vitellogenin II gene upstream sequences, an estrogen and a progestin response elements act synergistically. In this case again, no cooperativity of binding of the estrogen and progesterone receptors to their respective binding sites was observed. We therefore conclude that cooperative receptor binding may not always be required for synergistic action of multiple HREs.

Characterization of the hormone responsive element involved in the regulation of the progesterone receptor gene

The transcription of the progesterone receptor gene is induced by estrogens and decreased by progestins. Studies were performed to define the regions of the gene and the molecular mechanisms involved. No hormonal regulation could be observed using 5' flanking regions of the gene up to -2762 in front of a heterologous gene. Estrogen and progestin regulation could be observed only when using fragments of the gene extending down to +788. Progressive deletions from the 5' and 3' ends, site-directed mutagenesis and DNase protection experiments with purified estrogen receptor suggested that the biologically active estrogen responsive element (ERE) is present at +698/+723, overlapping the initiation of translation. An oligonucleotide was synthesized bearing this ERE and shown to impart estrogen inducibility to a heterologous gene. Its regulation by anti-estrogens corresponded to that of the in situ progesterone receptor gene since tamoxifen was a partial agonist whereas ICI 164384 was a full antagonist. This ERE also mediated down-regulation by progestins in the presence of the progesterone receptor, even though it has no progesterone receptor binding ability. DNase footprinting showed that this effect was not due to a decrease of estrogen receptor affinity for the ERE in the presence of progesterone receptor. Finally, use of deletion mutants of the progesterone receptor showed that the steroid binding and the DNA binding domains were necessary for down-regulation whereas deletions of various parts of the N-terminal domain were without effect.

Molecular cloning of mast cell growth factor, a hematopoietin that is active in both membrane bound and soluble forms

We have previously reported the identification of a novel mast cell growth factor (MGF) that was shown to be a ligand for c-kit and is encoded by a gene that maps near the steel locus on mouse chromosome 10. We now report the cloning of cDNAs encoding the MGF protein. The MGF protein encoded by this cDNA can be expressed in a biologically active form as either a membrane bound protein or as a soluble factor. The soluble protein promotes the proliferation of MGF-responsive cell lines and, in the presence of erythropoietin, stimulates the formation of macroscopic [corrected] erythroid and multilineage hematopoietic colonies.