Marla Dubinsky, MD Director, Pediatric IBD Center Associate Professor of Pediatrics Abe and Claire Levine Chair in Pediatric IBD Cedars-Sinai Medical Center Optimizing the efficacy of immunomodulators and biologics in pediatric IBD

Objectives Causes of non response to therapies Thiopurine drug monitoring Anti-TNF drug monitoring Impact of immunogenicity The future of biologic use

Potential Causes of Drug Response Heterogeneity  pathogenesis and severity of disease  drug interactions  age  nutritional status  renal and liver function  concomitant illnesses  genetic polymorphisms in targets of therapy  inherited differences in metabolism and disposition

6-TGN QUARTILES Frequency of Response 41% 78% n= n= n= n= P< Target 6-TGN Level to Optimize Efficacy: >235 Dubinsky MC et al. Gastroenterol;118:2000 Odds Ratio 5.0 for treatment response when 6-TGN > 235

Author & YearPatients (Remissi on) 6TGN Threshold Proportion Above Threshold in Remission Proportion Below Threshold in Remission Odds Ratio 95% Confidence Interval Dubinsky (30) Gupta (47) Belaiche (19) Cuffari (47) Goldenberg (15) Achkar (24) Pooled Estimate % CI % CI Meta-Analysis: 6-TGN levels and Clinical Remission Lewis J et al. Gastroenterology 2006:130;

Monitoring Levels of Thiopurines is Useful Because…. 1) Standard dosing only 30% effective 2) Safe dose escalation to maximize efficacy 3) Identify non compliance 4) Minimize toxicity 5) Identify preferential 6-MMP metabolism 6) Explain non response 7) Improves patient outcomes

150,000 IBD patients are currently on anti-TNFs 50% of IBD patients will require dose modification or switch to another treatment 1 Many patients with IBD who have symptoms may not have active inflammation Monitoring strategies that identify patients who have insufficient drug, anti-drug antibodies, or patients whose symptoms are due to causes other than active IBD may help guide treatment outcomes for individual patients Anti TNFα monitoring is Useful Because…. Alzafiri et al. Clinical and Experimental Gastroenterology 2011; (4):9-17

Effect of Trough Serum Infliximab Concentrations on Clinical Outcome at >52 Weeks Trough serum infliximab Detectable Undetectable Maser et al. Clin Gastroenterol Hepatol. 2006; 4: Patients in remission (%) Patients with endoscopic improvement >75% (%) Patients with complete endoscopic remission (%) Patients with CRP <5 mg/dL (%) p<0.001 p=0.03 p<0.001

ACCENT I: Week 54 Sustained Clinical Outcome and Week 14 Serum Infliximab Level in Crohn’s Disease Sustained Clinical Outcome <3.5 μg/mL Week 14 Serum IFX Level ≥3.5 μg/mL Week 14 Serum IFX LevelP-value* Subjects included in analysis 9651 Subjects with sustained response 17 (17.7%) 20 (39.2%) Subjects without sustained response 79 (82.3%) 31 (60.8%) *Chi-square test Cornillie F, et al. Presented at the 19 th Annual United European Gastroenterology Week (UEGW); October 25, Stockholm, Sweden. Abstract P0919.

Week 54 Outcome IFX14 Positive P value ATI14 * Positive P value Persistent Remission 70% vs. 36% P < % vs. 60% P = 0.58 Clinical Remission77% vs. 50% P = % vs. 70% P > 0.99 Deep Remission67% vs. 37% P = % vs. 58% P > 0.99 Sustained Durable Remission 14 43% vs. 14% P = % vs. 38% P = 0.28 Sustained Durable Remission 22 50% vs. 14% P = % vs. 43% P = 0.15 Detectable week 14 Infliximab Trough levels are associated with week 54 Efficacy Outcomes *Only 4 patients ATI14 positive Rosenthal C et al 2013

IFX14 < 3 IFX14 > 3 Fisher P value IFX14 < 5.5 IFX14 > 5.5 Fisher P value IFX14 < 6.8 IFX14 > 6.8* Fisher P value Persistent Remission (N = 26) 45%65%0.5448%85% %100% 0.01 Results: Optimal IFX14 Trough Level * Regression Tree analysis identified optimal cut point

Serum Infliximab Trough Levels and Steroid-free Remission at Week 30 Sonic Study Steroid-free Clinical Remission at Week 26 by IFX Trough Level at Week 30 Median IFX Concentration N=97N=109 19/3213/2343/5936/4931/43 Web figures 5a and 5b. Accessed on October 12, 2012.

Proportion of Patients Achieving Clinical Remission by Serum IFX Concentration: ACT 1 and 2 IFX Conc. (% patients) 1st Quartile 2ndQuartile3rdQuartile 4th Quartile P-values Week % (<21.3μg/mL) 37.9% (≥21.3-<33μg/mL) 43.9% (≥33-<47.9μg/mL) 43.1% (>47.9μg/mL) P= Week % (<0.11μg/mL) 25.5% (≥0.11-<2.4μg/mL) 59.6% (≥2.4-<6.8μg/mL) 52.1% (>6.8μg/mL) P< Week % (<1.4μg/mL) 55.0% (≥1.4-<3.6μg/mL) 79.0% (≥3.6-<8.1μg/mL) 60.0% (>8.1μg/mL) P= At wks 8, 30 and 54, the proportion of patients achieving clinical remission increased with increasing quartiles of IFX concentrations. Reinisch W et al., Gastro Vol 142, Issue 5, suppl-1, May 2012, page S-114 ACT1 and ACT 2 cont’d

Detectable Serum Trough IFX Concentration is Associated with Higher Remission Rate and Endoscopic Improvement in UC Patients Undetectable serum IFX predicted an increased risk for colectomy (55% vs 7%; p<0.001) % of patients P<0.001 Seow CH et al. Gut 2010;59:49-54

Rapid IFX clearance: Mechanism of Non Response in UC Kevans D, et al. Presented at DDW; May 19, 2012.

Effect of Patient Factors on MAb Pharmacokinetics Patient factors identified with changes in IFX clearance –Weight –Albumin –ADA Impact on IFX clearance is substantial and should be considered for dose selection ADA, antidrug antibody ; IFX, infliximab Fasanmade AA, et al. Eur J Clin Pharmacol. 2009;65(12):1211. Xu Z, et al. A Population-based Pharmacokinetic Pooled Analysis of Infliximab in Pediatrics. Presented at the 41 st Annual Meeting of the American College of Clinical Pharmacology; September 23-25, 2012; San Diego, CA Clearance (L/day) Weight (kg) Clearance (L/day) Albumin (g/dL)

ADA Trough Above 0.33 µg/mL Predicts Clinical Response Karmiris K, et al. Gastroenterology. 2009;137: Patients with Sustained Clinical Response (%) Sustained Clinical Response (weeks) Log Rank: P=0.01 ADA TR>0.33 µg/mL, n=104 ADA TR<0.33 µg/mL, n=16

PURSUIT – Golimumab for the Induction and Maintenance of UC Sandborn WJ, et al. Presented at DDW; May 22, Abstract 943d. Phase 2: Clinical Endpoints by Serum Golimumab Concentration Quartile at Week 6 No exposure < 1 st Quartile 1 st and < 2 nd Quartile 2 nd and < 3 rd Quartile 3 rd Quartile

Factors Affecting Infliximab Clearance in CD Con. IS, concomitant immunosuppressant Fasanmade AA, et al. Clin Ther. 2011;33(7):946. Scheduled & Episodic Therapy ACCENT I (n=580)

Immunogenicity Immunogenicity is usually dependent on antibody construct, route of administration, target of the antibody, disease, and other factors –Therapeutic antibodies that deplete B-cells are less immunogenic than other MAbs MurineChimeric Hyper- Chimeric Human Immunogenicity Half-Life Complement and ADCC Route of Administration: SC > IM > IV Infliximab (chimeric) should be more immunogenic than adalimumab (human), but immunogenicity is similar. ADCC, antibody -dependent cell cytotoxicity; 1. A717D20C0E0E.html

Immunogenicity of TNF Antagonists: Patients With Detectable Antibodies to a TNF Antagonist IMS, immunosuppressant; RA, rheumatoid arthritis; UC, ulcerative colitis 1. Hanauer et al. Clin Gastroenterol Hepatol. 2004;2(7): Sandborn WJ, et al. Presented at DDW; May 19-24, Abstract T Sandborn WJ, et al. N Engl J Med. 2007;357: Schreiber S, et al. N Engl J Med. 2007;357: Summary of Product Characteristics for adalimumab. Abbott Laboratories. July Sandborn WJ, et al. Gut. 2007;56:1232. Patients, % Episodic MaintenanceScheduled Maintenance IMS-IMS+IMS-IMS+ Infliximab 1 (CD 5 mg/kg) (CD 10 mg/kg) 38%16%11%8%7%4% Infliximab 2 (UC 5 mg/kg) (UC 10 mg/kg) No data 19%9%2%4% Certolizumab 3 (PRECiSE I) 10%4% Certolizumab 4 (PRECiSE II) 24%8%12%2% Adalimumab 5 (RA, all doses) No data 12%1% Adalimumab 6 (CLASSIC II) 4%0%

Presence of ATI is Associated with a Higher Non- response Rate and Shorter Duration of Response Farrell RJ, et al. Gastroenterology 2003;124: ATI (+) N=19 ATI (-) N=33P-value Rate of Non-response to subsequent infusions 52%14% Median Duration of Response 28 days61 days0.007 Incidence of subsequent infusion reactions 40%5% Incidence of serious infusion reactions 28%0%

SONIC: Immunogenicity Results at Week 30* *Patients who had 1 or more PK samples obtained after their first study agent administration were included in the analysis. PK data at week 30 was not available for 1 patient treated with AZA + placebo, 3 patients treated with IFX + placebo, and 4 patients treated with AZA + IFX. AZA, azathioprine; IFX, infliximab; PK, pharmacokinetic; SONIC, Study of Biologic and Immunomodulator Naive Patients in Crohn’s Disease Colombel JF, et al. N Engl J Med. 2010;362(15):1383. Percent of Patients (%) AZA + placeboIFX + placeboAZA + IFX 1/89 87/89 15/10616/10672/ /120 PositiveNegativeInconclusive 98 0/ / /120 94

92% of the patients with a trough serum concentration measured below the threshold for detection were positive for AAA AAA Formation Lowers Adalimumab Trough Serum Levels in Patients with Crohn’s Disease AAA, antibodies against adalimumab; ADA, adalimumab; TR, trough serum concentration Karmiris K, et al. Gastroenterology. 2009;137:1628.

“an IFX level of <4 μg/mL measured 4 weeks after the first infusion had a PPV of 81% to detect the development of high ATIs during the later course of treatment” “an IFX level of >15 μg/mL measured 4 weeks after the first infusion was 80% predictive for the absence of ATIs during later follow-up” Serum IFX at Week 4 After an Infusion Predicts Eventual Appearance of ATI’s in Episodic Dosing ATI, antibodies to infliximab; IFX, infliximab; PPV, positive predictive value Vermeire S et al. Gut. 2007;56(9);1226. Week 4 Serum Level and Subsequent ATI Titre P<0.001 P=NS ATI <8 ATI >8 ATI ?? Serum IFX Level (µg/ml)

N=57, Patients were selected based on ATIs detected on at least one time point during follow-up 788 serum samples were analyzed for IFX trough levels (ITL) and ATIs Treatment decisions to optimize and stop therapy were made on clinical grounds and CRP and not on ATI or ITL. Transient versus Sustained Antibodies to Infliximab: Possibility to Overcome Low Titer Antibody Responses by Dose Optimization Before the second infusion 20% of pts who had “late persisting ATIs“ had an undetectable ITL Concomitant immunomodulator use was associated with less ATI formation Van de Casteele N, et al. Presented at the 7 th Congress of ECCO; February 16-18, Barcelona, Spain. Abstract P253.  ATIs may be transient and can disappear after dose optimization.  Sustained high levels of ATIs lead however to permanent loss of response.  When low or undetectable ITL are detected measuring ATIs is necessary.  Low titer ATIs can be overcome by treatment optimization. High ATIs necessitate treatment stop. Early ATI FormationTreatment Discontinuation after Dose Optimization n=19n=38

Goal: Find objective IFX cutoff using CRP High CRP should predict low IFX & vice versa Results: IFX Liquid Phase ROC Analysis AUC, area under the curve; CRP, c-reactive protein; FPR, false positive rate; IFX, infliximab; ROC, receiver operating characteristic; TPR, true positive rate Feagan B, et al. Gastroenterology. 2012;142(5) Suppl 1: S-114. Abstract 565. Cutoff (μg/ml) ROC AUC95% C.I , , , TPR FPR AUC=0.735

 IFX assay LLOQ 0.1 μg/ml  ATI+ serum samples significantly lower odds of having detectable IFX – Odds ratio = 0.040, P<  154/353 (44%) ATI+ serum samples had detectable IFX ATI−ATI+ IFX−3.7%13.4% IFX+72.6%10.4% IFX- IFX+ IFX & ATI Counts LLOQ, lower limit of quantification

1,487 serum samples from 483 participants in 4 CD RCTs/cohorts Disease activity measured by CRP 1,205 pairs of samples taken over sequential time points (trough infliximab/ATI in first sample, CRP in second sample) Predictors of higher CRP: ATI+, infliximab < 3mcg/mL Novel Infliximab and Antibody-to-Infliximab Assays Are Predictive of Disease Activity in Patients with CD Feagan B, et al. Presented at DDW; May 20, Abstract 565. CRP mg/L ATI-ATI IFX < 3 µg/ml IFX ≥ 3 µg/ml Median CRP (mg/L) *** Sample size

Clinical Outcomes of Patients with Detectable Antibodies to Infliximab or Sub-therapeutic Infliximab Concentrations Response to test Complete/partial response (%)P value Detectable HACAIncrease infliximab Change anti-TNF 1/6 (17) 11/12 (92) P<0.004 Subtherapeutic concentration Increase infliximab Change anti-TNF 25/29 (86) 2/6 (33) P<0.016 Elevating Infliximab Concentration from Sub-Therapeutic Levels is Effective in Regaining Response in HACA (-) Patients HACA, Human anti-chimeric antibodies Afif W, et al. Am J Gastroenterol. 2010;105(5):1133.

Treatment Paradigms in Symptomatic Patients that Lose Response to IFX ATI - ATI+ IFX < threshold Increase dose Switch (high ATI) or Dose optimize (low ATI) IFX ≥ thresholdCheck endoscopy Switch (high activity) or Switch or Monitor (low activity)

 Only 43% have optimal ITL. In the others dose adjustment was carried out.  9% of the patients have undetectable ITL despite staying in remission.  The current controlled study will show whether long term adjustment of treatment based on IFX levels is a superior strategy. 270 IBD patients on IFX maintenance therapy. All pts had their IFX trough levels adjusted to 3-7 ug/ml. They were then randomized to dosing based on IFX trough levels (ITL) –Group 1: ITL kept between 3 and 7 μg/ml –Group 2: dosing and optimization based on clinical symptoms Individualized IFX Treatment Using Therapeutic Drug Monitoring: A Prospective Controlled Trough Level Adapted InfliXImab Treatment (TAXIT) Trial Infliximab EMEA SPC: 5 mg/kg IV infusion over a 2-hour period Van de Casteele N, et al. Presented at the 7 th Congress of ECCO; February 16-18, Barcelona, Spain. Abstract OP11. Decreased doseIncreased dose (77%) were ATI positive

Therapeutic Drug Monitoring for Anti-TNFα Measurable drug level associated with improved response outcomes Anti-infliximab antibodies associated with decreased efficacy ATI and drug levels can help guide treatment decisions Dose ranges should be studied during drug development given pharmacokinetic variability