6-MP and AZA Applications and Approaches Marla Dubinsky, MD Chief, Pediatric GI and Hepatology Co-Director, Susan and Leonard Feinstein IBD Clinical Center Icahn School of Medicine Mount Sinai Hospital, New York

Metabolism of AZA/6-MP 6-thiouric acid XO HPRT AZA 6-MP 6-TGNs TPMT 6-MMP

TPMT Activity Distribution Wild type Homozygous mutation Heterozygous www.nzma.org.nz/ journal/118-1210/1324/ Cies C et al. NZ Med J 2005;118:1324

Adverse Event Comparison* Safety of Starting Full Weight-Based Dosing vs. Low-Dose Thiopurines in Normal Metabolizers (TPMT >25) Complication Rates in Patients Starting Full-Dose Thiopurines vs. Controls (Gradual Increase) Retrospective study of 134 adult CD patients with TPMT > 25 (normal metabolizers) and > 1 year follow-up Dose initiation at 2-2.5mg/kg AZA or 1-1.5 mg/kg 6MP (therapy) compared with gradual increase (control) Results Overall similar rates of AEs 90% of complications in both groups occurred in first 3 months Adverse Event Comparison* Benmassauod A, et al. Presented at DDW; May 4, 2014. Abstract Su1416.

Target 6-TGN Level to Optimize Efficacy: >235 78% Frequency of Response Odds Ratio 5.0 for treatment response when 6-TGN > 235 41% n=44 0-173 n=42 174-235 n=43 236-367 n=44 368-1203 6-TGN QUARTILES Dubinsky MC et al. Gastroenterol2000;118:

Association of 6-thioguanine nucleotide levels and IBD activity: a meta-analysis Osterman MT. Gastroenterology 2006;130:1047-53.

Prospective Data Supporting Metabolite-Based Dose Optimization of Thiopurines are Inconclusive Multicenter RCT comparing AZA dosing - weight-based (2.5 mg/kg/day) versus individualized (stratified by TPMT, then optimized to target 6TGN – 250-400 pmol/8 x 108RBC) Powered for 226 subjects, 50 subjects randomized, 27 subjects completed p=0.11 p=0.12 Per Protocol Intention To Treat Dassopoulos T, et al. Aliment Pharmacol Ther 2014;39: 163-175

6-MP Metabolite Profiles 6-TGN 450 235 5700 6-MMP Dose Too Low; Noncompliant Therapeutic Range Preferential 6MMP Toxicity

AZA/6-MP as Maintenance Therapy in Crohn’s Disease after Steroid Induction Duration of Trial (months) Remission Duration (days) 80 60 40 20 % Patients Not Failing Trial 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 AZA 2.5 mg/kg/d (n=33) Placebo (n=30) 100 P=0.001 *Remission induced by prednisolone tapered over 12 wk. 200 300 400 500 600 0.00 0.25 0.50 0.75 1.00 6MP Control Fractional Survival ADULTS CHILDREN Candy S et al. Gut. 1995;37(5):674-678. Markowitz, et al. Gastroenterology. 2000;119(4):895-902.

Cosnes J et al. Gastroenterology 2013;145: 758-65 Early “top-down” therapy with azathioprine is not more effective than placebo or conventional therapy RAPID AZTEC Cosnes J et al. Gastroenterology 2013;145: 758-65

Predictors of surgery within 5 years of Crohn’s diagnosis Chatu S et al Am J Gastroenterol 2014;109:409-16

The Role of Thiopurines in Reducing the Need for Surgical Resection in Crohn’s disease: Systematic review and meta-analysis Chatu S et al. Am J Gastroenterol. 2014 Jan;109:23-34

Thiopurines Use and Surgical Rates: UK Chatu S et al Am J Gastroenterol 2014;109:409-16

Azathioprine and 6-mercaptopurine for maintenance of surgically-induced remission in Crohn's disease Gordon M et al Cochrane database syst rev 2014;8:CD010233

Predictors of Thiopurine response 6-TGN > 250 pmol per 8 . 108 RBC 4.14 (1.49-11.46) Relative Leukopenia 14.01 (3.77-52.10) Absence of lymphopenia 3.71 (1.26-10.89) Platelet (K/ul) 0.995 (0.991-0.999) TPMT activity (nmole/n/ml) 0.89 (0.80-0.98) AST (UI/L) 1.05 (1.01-1.09) 6MeMPN:6-TGN ratio 0.95 (0.85-1.04) Nguyen TV, et al R Inflamm Bowel Dis. 2013 Oct;19(:2404-10

Time To Relapse post Thiopurine Withdrawal Kennedy NA et al APT 2014:40;1313-2013

Predictors of Relapse post Thiopurine Withdrawal Kennedy NA et al APT 2014:40;1313-2013

Combined Immunosuppressive Therapy versus Conventional Management in Early Crohn’s Disease Clinical Results at 2 Years Primary Endpoint: Proportion of patients in remission CDAI < 150 No Steroids, No Surgery methylprednisolone Azathioprine/6-MP infliximab D’Haens et al. Lancet. 2008(9613);371:660-667.

Median disease duration 2.4 years SONIC: Corticosteroid-free Clinical Remission in CD at Week 26 Median disease duration 2.4 years P=.006 P=.02 P<.001 Patients (%) 51/170 75/169 96/169 Colombel JF, et al. N Engl J Med. 2010; 362(15):1383-1395.

Median disease duration 2 years Infliximab in Children Study (REACH) Shorter Disease Duration Median disease duration 2 years p=0.002 Patients (%) P<0.001 n=99 n=66 n=33 n=29 n=17 n=12 Overall number of subjects n=112 Antibodies to infliximab in 3 (2.9%) patients (1 in each maintenance arm and another not randomized) Hyams J, et al. Gastroenterology. 2007;132(3):863-873.

SONIC: Infliximab Trough Levels at Week 30 Colombel JF, et al. N Engl J Med. 2010;362(15):1383.

Percent of Patients (%) SONIC: Immunogenicity Results at Week 30 100 98 Positive Negative Inconclusive 94 80 68 60 Percent of Patients (%) 40 20 14 15 1/89 2/120 0/89 1/120 1 1 2 87/89 15/106 16/106 72/106 113/120 AZA + placebo IFX + placebo AZA + IFX Colombel JF, et al. N Engl J Med. 2010;362(15):1383.

6-Thioguanine Concentrations Are Associated With Higher Trough Infliximab Concentrations In IBD Patients On Combination Therapy Cross-sectional study of IBD patients (N=72, 63% CD) receiving IFX in combination with a thiopurine for ≥4 months Correlation Between 6-TGN and IFX Concentrations Comparison Between Groups With and Without Detectable Antibodies to IFX (ATI) Higher 6-TGN levels correlate with higher IFX trough concentrations but levels of 125 may maximize IFX levels Patients with detectable IFX antibodies had significantly lower 6TGN levels Yarur A, et al. Presented at DDW, May 5, 2014 Abstract 788.

Maintenance of Remission Induction of Remission Azathioprine Decreases the Risk of Adalimumab Primary Non-Response and Secondary Loss of Response If Adequately Dosed  CD patients on combination immunomodulator (IM) plus adalimumab (n=76) vs. adalimumab monotherapy (n=46) followed for mean of 21 months Maintenance of Remission (Semester Analysis) Induction of Remission IM for 3 months prior to starting adalimumab improves response at 12 weeks Semester analysis showed lower flare and failure rates only if thioguanine (TGN) levels were therapeutic (>235 pmol/8x108 RBC) Kariyawasam V, et al. Presented at DDW; May 4, 2014 Abstract 343.

Withdrawal of Immunomodulator and Infliximab Dose Escalation and Discontinuation Drobne D. et al CGH 2014 epub ahead of print

Levels Pre and Post IMM withdrawal Drobne D. et al CGH 2014 epub ahead of print

Trough Levels at Time of IMM Withdrawal Predict Infliximab Dose Escalation Drobne D. et al CGH 2014 epub ahead of print

6-MP/AZA Approaches and Applications :Summary Thiopurine Levels are associated with improved efficacy Role of thiopurines as steroid sparing maintenance strategy questionable Thiopurines protective of surgery but post operative effectiveness needs further exploration Combination therapy with thiopurine and anti-TNF is more effective than monotherapy Combination therapy decreased ATI and improves Anti TNF drug levels Anti-TNF levels remain stable after stopping thiopurine