Abstract This study aimed to define the clinically relevant supratherapeutic dose of rilzabrutinib, an oral Bruton tyrosine kinase (BTK) inhibitor, and evaluate potential effects of therapeutic and supratherapeutic exposures on cardiac repolarization in healthy subjects. This was a two‐part phase I study (anzctr.org.au ACTRN12618001036202). Part A was a randomized, open‐label, three‐period, single‐dose crossover study (n = 12) with rilzabrutinib 100 mg ± ritonavir 100 mg or rilzabrutinib 1200 mg. Part B was a randomized, double‐blind, placebo‐controlled, four‐way, single‐dose crossover study (n = 39) with matched placebo, rilzabrutinib 400 mg ± ritonavir 100 mg, or moxifloxacin (positive control). Primary objectives: part A – pharmacokinetics (PK) of rilzabrutinib ± ritonavir, safety, and optimal dose for Part B; Part B – effect of rilzabrutinib therapeutic and supratherapeutic concentration on electrocardiogram (ECG) parameters. ECGs and PK samples were serially recorded before and post‐dose. In part A, rilzabrutinib 100 mg + ritonavir led to 17‐fold area under the concentration–time curve (AUC0–∞) and 7‐fold maximum plasma concentration (Cmax) increases over rilzabrutinib alone. Rilzabrutinib 1200 mg was discontinued due to mild‐to‐moderate gastrointestinal intolerance. In Part B, rilzabrutinib 400 mg + ritonavir increased rilzabrutinib mean AUC0–∞ from 454 to 3800 ng h/mL and Cmax from 144 to 712 ng/mL. The concentration–QTc relationship was slightly negative, shallow (−0.01 ms/ng/mL [90% CI −0.016 to −0.001]), and an effect >10 ms on QTcF could be excluded within the observed range of plasma concentrations, up to 2500 ng/mL. Safety was similar to other studies of rilzabrutinib. In conclusion, rilzabrutinib, even at supratherapeutic doses, had no clinically relevant effects on ECG parameters, including the QTc interval.

Introduction: Key characteristics of immune thrombocytopenia (ITP) include immune-mediated platelet destruction/impaired production, with resultant thrombocytopenia and increased bleeding risk. Durable response to current therapies remains an unmet need, particularly in the relapsed/refractory setting. Rilzabrutinib is the first oral, reversible, covalent inhibitor of Bruton tyrosine kinase designed to target immune-mediated pathways in ITP without inhibiting normal platelet aggregation. Initial phase I/II results in ITP demonstrated rapid and durable efficacy with rilzabrutinib that was well-tolerated at all dose levels, including the optimal 400 mg bid dose. Interim results on rilzabrutinib effects in patients with relapsed/refractory ITP were previously reported. Here we present long-term data from a larger group of patients who initiated rilzabrutinib at 400 mg bid and are continuing in the long-term extension (LTE) period.

Abstract Introduction: Itolizumab is a first-in-class monoclonal antibody against the co-stimulatory receptor CD6 that blocks its interaction with activated leukocyte cell adhesion molecule (ALCAM), thereby inhibiting T effector (T eff) cell activity and trafficking to target organs. It is being evaluated as a treatment for immuno-inflammatory diseases where T eff cells play a central role including acute graft-versus-host disease (aGVHD). Previous studies reported that ex vivo depletion of donor CD6+ cells in allogeneic hematopoietic cell transplantations lowers the incidence of aGVHD, justifying therapeutically targeting CD6 in aGVHD. Here we present interim clinical and pharmacokinetic/dynamic (PK/PD) results from the EQUATE study (NCT03763318), an ongoing US-based Phase 1b/2 study of itolizumab (a non-depleting anti-CD6 mAb) to treat subjects with newly diagnosed aGVHD, highlighting the relationship of early response to itolizumab concentrations. Methods: To date, 22 adult subjects with Grade III-IV aGVHD who initiated steroid treatment within 7 days prior to the first dose of itolizumab have enrolled in EQUATE at 0.4 mg/kg (n=4), 0.8 mg/kg (n=9), or 1.6 mg/kg (n=9), administered IV every 2 weeks x 5 doses. The median follow-up is 146 days (range: 14-355 days). Primary endpoints included itolizumab safety, tolerability, and optimal dose levels, and secondary endpoints included PK/ PD effects (change in CD6 surface expression on CD4+ cells) and clinical activity. Results: Patients: At baseline, study subjects had a mean (SD) age of 54 (14) and 68% were male; all had Grade III or IV aGVHD and 91% had lower GI involvement. All subjects received at least one dose and 15 received at least 2 doses of itolizumab. Safety: All subjects experienced at least 1 AE. Serious AEs occurred in 14 subjects (64%), with 9 (41%) reporting infection-related SAEs. There were 8 deaths. Six subjects (27.3%) had SAEs leading to death (3 at 0.8 mg/kg and 3 at 1.6 mg/kg): sepsis (n=1), Staphylococcal sepsis (n=1), Klebsiella sepsis (n=1), intestinal infarction (n=1), cardiac arrest (n=1), and GVHD (n=1). Another 2 deaths occurred >100 days post- last dose due to progressive aGVHD (n=1) and primary disease relapse (n=1). Efficacy and Survival: Across all doses, the complete response (CR) rate was 55% at both Day 15 and Day 29, and the overall response rate (ORR) was 73% at Day 15 and 68% at Day 29. At Day 169 (n=20), non-relapse mortality (NRM) was 35%, overall survival was 65%. Of note, the 10 subjects who achieved an early CR at Day 15 had a lower rate of NRM at Day 169 (20%) compared to the 10 subjects who had a very good partial response (VGPR), partial response (PR), no response (NR), or disease progression (50%). PK/PD: Itolizumab substantially decreased the levels of cell surface CD6 on circulating T cells after the first dose in a dose-dependent manner and maintained that decrease throughout the treatment period (Figure 1). Notable findings by immunophenotyping included: (1) an increase in the ratio of T regulatory to T eff cells at 0.8 and 1.6 mg/kg dose-level by Day 15, and (2) decreases of PD-1 expression on T cells and of ALCAM on CD14+ monocytes at all dose-levels by Day 8. This indicates itolizumab can reduce activation of T eff cells and monocytes. The relationship between drug concentrations and efficacy was evaluated at Day 15 when there was greater variability in response relative to later timepoints. Higher itolizumab trough concentrations on Day 15, achieved at higher dose-levels, correlated with a higher rate of CR at Day 15 (Figure 2). Conclusions: In summary, the observed safety, efficacy, PK and PD to date from this ongoing study indicate a favorable benefit-risk profile in subjects with Grade III-IV aGVHD. The relationship between itolizumab concentrations after the first dose and clinical response suggest that higher itolizumab exposures early (by Day 15) are impactful for longer term clinical responses. These data support the design and initiation of a pivotal phase 3, placebo-controlled clinical trial to assess itolizumab in combination with corticosteroids as first-line treatment of aGVHD. Figure 1 Figure 1. Disclosures Koreth: Equillium: Research Funding; Regeneron: Research Funding; Clinigen Labs: Research Funding; BMS: Research Funding; Miltenyi Biotec: Research Funding; Gentibio Inc.: Consultancy; EMD Serono/Merck: Consultancy; Amgen: Consultancy; Moderna: Consultancy; Cugene: Other: Scientific Advisory Board; Mallinckrodt: Other: Scientific Advisory Board; Biolojic Design: Other: Scientific Advisory Board. Ritz: Amgen: Research Funding; Equillium: Research Funding; Kite/Gilead: Research Funding; Avrobio: Membership on an entity's Board of Directors or advisory committees; Akron: Consultancy; Biotech: Consultancy; Blackstone Life Sciences Advisor: Consultancy; Clade Therapeutics, Garuda Therapeutics: Consultancy; Immunitas Therapeutic: Consultancy; LifeVault Bio: Consultancy; Novartis: Consultancy; Rheos Medicines: Consultancy; Talaris Therapeutics: Consultancy; TScan Therapeutics: Consultancy. Chinn: Equillium: Current Employment, Current equity holder in publicly-traded company; Principia Biopharma: Divested equity in a private or publicly-traded company in the past 24 months, Ended employment in the past 24 months; Genentech/Roche: Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months, Ended employment in the past 24 months, Patents & Royalties: Methods of treating immune diseases using an inhibitor of Bruton's tyrosine kinase (provisional patent application. Ng: Equillium: Current Employment, Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months. Acevedo: Equillium: Current Employment, Current equity holder in publicly-traded company; Arena: Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months, Ended employment in the past 24 months. Chu: Equillium: Current Employment. Fung: Equillium: Current Employment; Arena: Ended employment in the past 24 months, Patents & Royalties. Rothman: Equillium: Current Employment, Current equity holder in publicly-traded company. Connelly: Equillium: Current Employment, Divested equity in a private or publicly-traded company in the past 24 months, Membership on an entity's Board of Directors or advisory committees. Thomas: Equillium: Current Employment, Current equity holder in publicly-traded company; Chinook: Current equity holder in publicly-traded company, Honoraria, Membership on an entity's Board of Directors or advisory committees; Principia: Current equity holder in publicly-traded company, Ended employment in the past 24 months. Cutler: Deciphera: Consultancy; Cimeio: Consultancy; Editas: Consultancy; Kadmon: Consultancy; Pfizer: Consultancy; Mallinckrodt: Consultancy; CareDx: Consultancy; Incyte: Consultancy; Omeros: Consultancy; Syndax: Consultancy; Mesoblast: Consultancy; Jazz: Consultancy.

Introduction: Rilzabrutinib is an oral, reversible, covalent inhibitor of Bruton tyrosine kinase (BTK) that targets underlying disease mechanisms of platelet destruction without inhibiting platelet aggregation (common with ibrutinib). The mechanisms of BTK inhibition provide a new approach for treating patients with immune thrombocytopenia (ITP). Completion of dose-escalation study phase determined that the minimally-effective dose was rilzabrutinib 400 mg given twice daily (BID; Kuter. ASH 2019). Methods: This open-label phase I/II study evaluated rilzabrutinib in adults with relapsed ITP who had at least two platelet counts <30×109/L in the 14 days prior to the first dose of rilzabrutinib, and included patients who had inadequate response to prior corticosteroids (CS)/thrombopoietin receptor agonists (TPO-RA) but were allowed to continue receiving stable doses of these medications. The primary endpoint was ≥2 consecutive platelet counts of ≥50×109/L and an increase of ≥20×109/L from baseline without requiring rescue medication. Subgroup analyses included assessing the impact of select prior therapies on reaching the primary endpoint, as well as the ability of rilzabrutinib to maintain durable responses and safety in the long-term extension (LTE) period. Results: As of May 5, 2020, 32 patients initiated treatment with rilzabrutinib 400 mg BID. The median baseline age was 50 years (range, 21-74) and 97% were classified as having primary ITP. Patients had a median baseline platelet count of 13×109/L, had ITP for a median duration of 7.3 y (range, 0.4-52.5), and were heavily pretreated with a median of 6 prior therapies (range, 1-53; 28% prior splenectomy). Median duration of rilzabrutinib 400 mg BID treatment was 18.0 wk (range, 1.4-24.6). Overall, 14/32 patients (44%) achieved the primary endpoint, and responders maintained platelet counts ≥50×109/L for a median of 71% (range, 33%-100%) of weekly counts. Primary endpoint responses were achieved despite prior splenectomy or lack of response to prior ITP therapies (Table). Independent of the primary response, 67% of all patients were able to achieve clinically meaningful benefit of platelet counts ≥30×109/L. Nine patients continued rilzabrutinib 400 mg BID into the LTE period for an additional median of 20 wk (range, 4-36) of treatment. Four of these LTE patients were on rilzabrutinib monotherapy and 5 on rilzabrutinib with concomitant ITP therapy (n=3 corticosteroids, n=2 romiplostim). Baseline characteristics for the 9 LTE patients were a median duration of ITP of 2.6 y (1.2-14.3) and a median of 5 prior therapies (range, 1-8; 1 patient had a prior splenectomy). Platelet counts of ≥50×109/L in the LTE period were maintained for a median of 100% (range, 36%-100%) of weekly counts (Figure). Treatment-related, treatment-emergent adverse events (TEAEs) were all grade 1/2 in patients initiating rilzabrutinib 400 mg BID; 1 patient each experienced grade 1 diarrhea and grade 1 hypophosphatemia in the LTE period. Conclusions: Oral rilzabrutinib treatment achieved clinically significant platelet responses (≥50×109/L) in patients with heavily pretreated ITP irrespective of splenectomy or lack of response to prior ITP therapy, and maintained responses for the majority of time. In addition, most patients (67%) achieved a clinically meaningful response (platelet counts ≥30×109/L). In patients treated beyond 6 months in the LTE, responses remained consistently reliable (median 100% of weeks). Rilzabrutinib was well tolerated with only grade 1/2 treatment-related TEAEs overall, with only 2 related grade 1 events observed in the LTE period. Continued study is warranted to further demonstrate the magnitude and durability of rilzabrutinib's clinical benefit. Disclosures Kuter: Zafgen: Consultancy, Honoraria; Takeda (Bioverativ): Consultancy, Honoraria, Other, Research Funding; Merck Sharp Dohme: Consultancy, Honoraria; Kyowa-Kirin: Consultancy, Honoraria; UCB: Consultancy, Honoraria; Platelet Disorder Support Association: Consultancy, Honoraria; Incyte: Consultancy, Honoraria; Shionogi: Consultancy, Honoraria; Dova: Consultancy, Honoraria; Shire: Consultancy, Honoraria; Sanofi (Genzyme): Consultancy, Honoraria; Protalix Biotherapeutics: Consultancy; Up-To-Date: Consultancy, Honoraria, Patents & Royalties; Protalex: Consultancy, Honoraria, Research Funding; Shionogi: Consultancy; Genzyme: Consultancy, Honoraria; Immunovant: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Actelion (Syntimmune): Consultancy, Honoraria, Other: Travel Expenses, Research Funding; Protalex: Consultancy, Honoraria, Other, Research Funding; Rigel: Consultancy, Honoraria, Other, Research Funding; Daiichi Sankyo: Consultancy, Honoraria; Agios: Consultancy, Honoraria, Other: Travel Expenses, Research Funding; Caremark: Consultancy, Honoraria; CRICO: Consultancy, Honoraria; Kezar Life Sciences, Inc: Other, Research Funding; Principia Biopharma: Consultancy, Honoraria, Other, Research Funding; Amgen: Consultancy, Honoraria, Other: Travel Expenses, Research Funding; Alnylam: Consultancy, Honoraria, Other: Travel Expenses, Research Funding; Immunovant: Other: Travel Expenses, Research Funding; Principia: Consultancy, Research Funding; Momenta: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria, Other: Travel Expenses, Research Funding; Argenx: Consultancy, Honoraria, Other: Travel Expenses, Research Funding; Novartis: Consultancy, Honoraria. Efraim:UMHAT"ST.MARINA": Consultancy, Current Employment, Current equity holder in private company. Mayer:AbbVie: Research Funding; Principia Biopharma: Research Funding. McDonald:Bayer: Consultancy, Honoraria; Rigel: Research Funding; Novartis: Consultancy, Honoraria, Other: Travel Expenses; Amgen: Consultancy, Honoraria, Other: Travel Expenses. Bird:Sanofi: Consultancy, Other: (pls note personal honoraria declined for ad board); Principia Biopharma: Other: investigator in clinical studies; Amgen: Consultancy, Other: (pls note personal honoraria declined for all), Speakers Bureau; Novartis: Consultancy, Other: (pls note personal honoraria declined for all), Speakers Bureau; Rigel: Other: investigator in clinical studies; CSL-Behring: Other: investigator in clinical studies; Bristol-Myers Squibb Company: Other: investigator in clinical studies; Ablynx: Other: investigator in clinical studies. Regenbogen:Roche: Current equity holder in publicly-traded company; Gilead: Current equity holder in publicly-traded company; Amgen: Current equity holder in publicly-traded company; Moderna: Current equity holder in publicly-traded company; AbbVie: Current equity holder in publicly-traded company. Garg:Takeda: Consultancy. Kaplan:Celgene: Honoraria; Novartis: Honoraria. Bandman:Principia Biopharma: Current Employment. Burns:Principia Biopharma: Current Employment. Neale:Principia Biopharma: Current Employment. Thomas:Principia Biopharma: Current Employment, Current equity holder in publicly-traded company. Cooper:Novartis: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Rigel: Consultancy, Honoraria; Principia: Consultancy, Honoraria. OffLabel Disclosure: Rilzabrutinib is an investigational therapy being evaluated in a clinical study for the treatment of patients with immune thrombocytopenia.

Background: Immune thrombocytopenia (ITP) is characterized by immune-mediated platelet destruction and impairment of platelet production, leading to downstream thrombocytopenia, a predisposition to bleeding, and adverse impact on patient quality of life. Unmet needs in relapsed or refractory ITP are to improve remission rates and durability through targeting underlying disease mechanisms. PRN1008 is an oral, reversible, covalent inhibitor of Bruton tyrosine kinase (BTK) that modulates immune-mediated processes in ITP. Preclinical PRN1008 data showed inhibition of B-cell receptor-mediated activation of human B cells, Fc receptor (Fc-gamma and Fc-epsilon)-mediated activation of immune cells, and dose-dependent reduction in platelet loss in a mouse ITP model. In platelets from normal healthy volunteer and ITP patients, clinically-relevant concentrations of PRN1008 showed no platelet aggregation or interference with other platelet agonists, in contrast to ibrutinib (Langrish et al. ASH 2017:1052). Methods: This is an ongoing open-label, adaptive, intra-patient dose-escalation, phase I/II study of PRN1008 in adult patients with relapsed or refractory ITP (primary or secondary) who previously responded to ≥ 1 prior ITP therapy and have no available therapeutic options (NCT03395210). Eligible patients have two platelet counts < 30,000/µL within 15 days prior to treatment. Oral PRN1008 starting doses were 200 mg QD, 400 mg QD, 300 mg BID (total 600 mg daily), and 400 mg BID (total 800 mg daily), with intra-patient dose escalation allowed every 4 weeks (maximum 400 mg BID) as needed for efficacy. Stable doses of concomitant corticosteroids and thrombopoietin-receptor agonists (TPO-RA) are permitted. The primary end point is the proportion of patients with ≥ 2 consecutive platelet counts (separated by ≥ 5 days) of ≥ 50,000/µL and increased by ≥ 20,000/µL from baseline without requiring rescue medication. Results: A total of 21 patients have been enrolled to date at starting doses of 200 mg QD (n=9), 400 mg QD (n=1), 300 mg BID (n=5), and 400 mg BID (n=6). As of 15 July 2019 data cut-off, 11 patients were receiving ongoing treatment, 4 completed the study, and 6 patients withdrew (2 due to patient decision, 2 from non-treatment-related adverse events [AEs], 1 erroneously enrolled, and 1 because of rescue medication use). Patients had a median age of 54 y (range, 30-65), 4 (19%) had a prior splenectomy, 19 (90%) were diagnosed with primary ITP, and 2 (10%) with secondary ITP. Patients had ITP for a median of 8.3 years (range, 0.5-42.4) and had received a median of 4 prior ITP therapies. Median platelet count at study entry was 14,173/µL (range, 2,670-27,000/µL). During the study, 6 (29%) patients received PRN1008 monotherapy; 15 (71%) patients were on ≥ 1 concomitant ITP medication. Related treatment-emergent AEs (TEAEs) were reported by 4 (19%) patients; all were grade 1 or 2. The most frequent related TEAEs were nausea, diarrhea, and abdominal distension. There were no treatment-related bleeding or thrombotic events, and no significant changes in the ITP-BAT bleeding scale between baseline and the last visit. There were no dose limiting toxicities (DLT). Patients had received treatment for a median of 10.1 weeks (range, 0.1-31.0). Overall, 7 (33%) patients achieved the primary endpoint across all doses (Table). Patient responses were improved at the 2 higher doses. In 10 patients who had reached ≥ 12 weeks of treatment, ≥ 50% of patients had platelet counts of ≥ 50,000/µL and ≥ 20,000/µL increases from baseline. Conclusion: Overall, PRN1008 was active in 33% of ITP patients who were refractory to multiple treatments with no alternative therapeutic options. This result was demonstrated despite the limited duration of treatment and including patients at all dose levels. In addition, patients treated for longer periods of time have substantially improved response rates that support continued interest in this ongoing study. The safety profile was tolerable at all studied doses whether given as a monotherapy or with allowed concomitant ITP therapy. Importantly, TEAEs were grade 1 or 2 with no thrombotic events. The dose-escalation portion of the study is complete; enrollment is expanding at the 400 mg BID starting dose for a duration of 24 weeks to further characterize treatment benefit and for continued treatment beyond 24 weeks in patients who have responded. Disclosures Kuter: Dova: Consultancy, Honoraria; Kyowa-Kirin: Consultancy, Honoraria; Caremark: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Kezar: Research Funding; Argenx: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria; Platelet Disorder Support Association: Consultancy, Honoraria; Principia: Consultancy, Honoraria, Research Funding; Alnylam: Consultancy, Honoraria, Research Funding; Bristol Myers Squibb (BMS): Consultancy, Honoraria, Research Funding; Agios: Consultancy, Honoraria, Research Funding; Sanofi: Consultancy, Honoraria; Genzyme: Consultancy, Honoraria; Shinogi: Consultancy, Honoraria; Shire: Consultancy, Honoraria; Merck Sharp Dohme: Consultancy, Honoraria; Momenta: Consultancy, Honoraria; Protalex: Consultancy, Honoraria, Research Funding; Protalix: Consultancy, Honoraria; Rigel: Consultancy, Honoraria, Research Funding; Takeda (Bioverativ): Consultancy, Honoraria, Research Funding; UCB: Consultancy, Honoraria; Up-to-Date: Consultancy, Honoraria, Patents & Royalties: 3 Up-to-Date chapters; Zafgen: Consultancy, Honoraria; Daiichi Sankyo: Consultancy, Honoraria; Actelion (Syntimmune): Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding. Boccia:AstraZeneca: Speakers Bureau; Celgene: Speakers Bureau; Amgen: Speakers Bureau; AMAG: Consultancy; Genentech: Speakers Bureau; DSI: Speakers Bureau. Lee:Weill Cornell Medical College: Employment. Tzvetkov:UMHAT Georgi Stranski: Employment; DCC Pleven: Consultancy. Mayer:AOP Orphan Pharmaceuticals AG: Research Funding. Trněný:Abbvie: Consultancy, Honoraria; Gilead Sciences: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; MorphoSys: Consultancy, Honoraria; Incyte: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Celgene: Consultancy; F. Hoffmann-La Roche: Consultancy, Honoraria; Amgen: Consultancy, Honoraria. Kostal:Novartis: Honoraria; AOP: Honoraria; University Hospital in Hradec Kralove, Czech Republic: Employment. Hajek:Janssen: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy; BMS: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Research Funding; PharmaMar: Consultancy, Honoraria; Takeda: Consultancy, Honoraria, Research Funding, Speakers Bureau. McDonald:Bayer: Honoraria; Amgen: Honoraria; Novartis: Honoraria. Bandman:Principia Biopharma: Employment, Equity Ownership, Patents & Royalties: Institutional with Incyte and Portola, no royalties. Burns:Principia BioPharma: Employment. Neale:Principia BioPharma: Employment, Equity Ownership. Thomas:Principia Biopharma: Employment, Equity Ownership; BMS: Equity Ownership; Pfizer: Equity Ownership. Cooper:Principia: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Rigel: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Off Label Disclosure: Yes, this was an investigational clinical phase I/II study of PRN1008 in patients with relapsed/refractory ITP. Phase I dose escalation phase is now complete and expanded phase II studies ongoing.

AimsPharmacokinetic (PK) similarity was assessed among PF‐05280586 (a proposed biosimilar) vs. rituximab sourced from the European Union (rituximab‐EU) and the United States (rituximab‐US). Pharmacodynamics (PD), overall safety and immunogenicity were also evaluated.MethodsPatients with active rheumatoid arthritis on a background of methotrexate and inadequate response to one or more tumour necrosis factor antagonist therapies were randomized to intravenous PF‐05280586, rituximab‐EU or rituximab‐US 1000 mg doses on study days 1 and 15.ResultsA total of 220 patients were randomized to receive study treatment as assigned. Of these, 198 met per‐protocol population criteria for inclusion in the PK data analysis. PF‐05280586, rituximab‐EU and rituximab‐US exhibited similar PK profiles following administration of assigned study drug on days 1 and 15. The 90% confidence intervals of test‐to‐reference ratios for Cmax, AUCT, AUC0–∞ and AUC2‐week were within the bioequivalence margin of 80.00–125.00% for comparisons of PF‐05280586 with rituximab‐EU, PF‐05280586 with rituximab‐US, and rituximab‐EU with rituximab‐US. All treatments resulted in a rapid and profound reduction in CD19+ B cells and sustained profound B cell suppression up to week 25. The incidence of antidrug antibody (ADA) response (n = 7, 10 and 9 for PF‐05280586, rituximab‐EU and rituximab‐US, respectively), time to ADA emergence and ADA titres were similar across treatments. None of the ADA‐positive samples was positive for neutralizing activity. No clinically meaningful differences in adverse events were identified.ConclusionsThe study demonstrated PK similarity among PF‐05280586, rituximab‐EU and rituximab‐US. In addition, all treatments showed comparable CD19+ B cell depletion PD responses, as well as safety and immunogenicity profiles.

Despite availability of biologic therapies, limited patient access to many of the most-effective cancer treatments affects overall health outcomes. To address this issue, many governments have enacted legislation for the approval of biosimilars. The term "biosimilar" refers to a biologic product that is developed to be highly similar, as opposed to identical, to a licensed biologic product (the reference or innovator product), such that, per US Food and Drug administration draft guidelines, "no clinically meaningful differences [exist] between the biological product and the reference product in terms of safety, purity, and potency." This article presents some considerations about the development of biosimilars in cancer treatment through an overview of biosimilars from a clinical perspective. Topics covered include the development requirements and unique regulatory requirements for biosimilars, labeling considerations, potential limitations to the uptake of biosimilars, and review of some biosimilars in development for oncology indications.

Acute and chronic shortages of various pharmaceuticals and particularly of sterile injectable products are being reported on a global scale, prompting evaluation of more effective strategies to manage current shortages and development of new, high-quality pharmaceutical products to mitigate the risk of potential future shortages. Oncology drugs such as liposomal doxorubicin and 5-fluorouracil represent examples of first-choice drugs critically affected by shortages. Survey results indicate that the majority of hospitals and practicing oncologists have experienced drug shortages, which may have compromised patient safety and clinical outcomes, and increased health care costs, due to delays or changes in treatment regimens. Clinical trials evaluating novel agents in combination with standard-of-care drugs are also being affected by drug shortages. Clinical and ethical considerations on treatment objectives, drug indication, and availability of alternative options may help in prioritizing cancer patients involved in active drug shortages. The United States Food and Drug Administration and the European Medicines Agency have identified manufacturing problems, delays in supply, and lack of available active ingredients as the most frequent causes of recent or ongoing drug shortages, and have released specific guidance to monitor, manage, and reduce the risk of shortages. The upcoming loss of exclusivity for a number of anticancer biologics, together with the introduction of an abbreviated approval pathway for biosimilars, raises the question of whether these products will be vulnerable to shortages. Future supply by reliable manufacturers of well characterized biosimilar monoclonal antibodies, developed in compliance with regulatory and manufacturing guidelines and with substantial investments, may contribute to prevent future biologics shortages and ensure access to effective and safe treatment options for patients with cancer. Preclinical and clinical characterization is ongoing for potential biosimilars of trastuzumab, rituximab, and bevacizumab, with promising results.

Kidney transplant recipients who switched from a calcineurin inhibitor (CNI) to belatacept demonstrated higher calculated glomerular filtration rates (cGFRs) at 1 year in a Phase II study. This report addresses whether improvement was sustained at 2 years in the long-term extension (LTE). Patients receiving cyclosporine or tacrolimus were randomized to switch to belatacept or continue CNI. Of 173 randomized patients, 162 completed the 12-month main study and entered the LTE. Two patients (n = 1 each group) had graft loss between Years 1-2. At Year 2, mean cGFR was 62.0 ml/min (belatacept) vs. 55.4 ml/min (CNI). The mean change in cGFR from baseline was +8.8 ml/min (belatacept) and +0.3 ml/min (CNI). Higher cGFR was observed in patients switched from either cyclosporine (+7.8 ml/min) or tacrolimus (+8.9 ml/min). The frequency of acute rejection in the LTE cohort was comparable between the belatacept and CNI groups by Year 2. All acute rejection episodes occurred during Year 1 in the belatacept patients and during Year 2 in the CNI group. There were more non-serious mucocutaneous fungal infections in the belatacept group. Switching to a belatacept-based regimen from a CNI-based regimen resulted in a continued trend toward improved renal function at 2 years after switching.

Epstein-Barr virus (EBV)-associated lymphomas are a known risk for immunosuppressed individuals. Non-clinical methods to determine the potential of new immunomodulatory compounds to produce EBV-associated lymphomas (hazard identification) have not been developed. Since lymphocryptovirus (LCV) in non-human primates (NHP) has similar characteristics to EBV in humans, a Roundtable meeting was held in October 2010 to explore how the potential for EBV-related lymphomas in humans can be assessed by using surrogate biomarkers for lymphoma risk in NHP toxicity studies. Stakeholders from regulatory agencies, academia, and industry came together to determine the research gaps and potential benefits and considerations of such an approach given the current state-of-the-science. Key conclusions from the discussion included considerations raised about the potential usefulness of LCV-related biomarkers from NHP studies since there is significant controversy over the reliability of using EBV viral load or EBV-specific T-lymphocytes to predict for lymphoproliferative disorders in transplant patients. In addition, there are technical challenges that need to be further addressed in order to develop methods to measure LCV viral load and LCV-specific T-lymphocytes from cynomolgus monkeys.

BACKGROUND AND OBJECTIVES:Renal transplant recipients with pre-existing diabetes (PD) have reduced graft survival and increased risk of mortality and ischemic heart disease compared with nondiabetic transplant recipients. To assess the effect of belatacept in this high-risk group, we evaluated outcomes of the subpopulation with PD from previously published BENEFIT and BENEFIT-EXT trials. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS:A post hoc analysis evaluated pooled data from BENEFIT (living donors or standard criteria donors) and BENEFIT-EXT (extended criteria donors). Patients were randomized to receive cyclosporine or a more intensive (MI) or less intensive (LI) belatacept regimen. RESULTS:Of 1209 intent-to-treat patients, 336 had PD. At 12 months, the belatacept LI arm demonstrated a numerically higher rate of patients surviving with a functioning graft (90.4% MI [103 of 114], 92.8% LI [90 of 97], and 80.8% cyclosporine [101 of 125]), and fewer serious adverse events than cyclosporine or MI patients. Three cases of posttransplant lymphoproliferative disorder were reported in LI patients, one involving the central nervous system. Higher rates (% [95% confidence interval]: 22.8% MI [15.1 to 30.5]; 20.6% LI [12.6 to 28.7]; 14.4% cyclosporine (8.2 to 20.6]) and grades of acute rejection were observed with belatacept. Measured GFR (ml/min per 1.73 m(2), 59.8 MI; 62.5 LI; 45.4 cyclosporine), and cardiovascular risk profile were better for belatacept versus cyclosporine. CONCLUSIONS:In post hoc analysis of patients with PD, patient/graft survival and renal function at 12 months were numerically higher with belatacept versus cyclosporine, but not statistically significant. Further study is necessary to confirm the benefits belatacept may provide in these patients.

BACKGROUND Posttransplant lymphoproliferative disorder (PTLD) is a major complication of kidney transplant. STUDY DESIGN Retrospective cohort study comparing PTLD incidence rates using US Medicare claims and Organ Procurement and Transplantation Network (OPTN) data, examining risk factors for PTLD in OPTN data, and studying recipient and graft survival after PTLD diagnosis. SETTING & PARTICIPANTS All adult first-transplant patients who underwent deceased or living donor kidney-only transplants in 2000-2006 (n = 89,485) followed up through 3 years posttransplant. PREDICTORS Recipient and donor characteristics, HLA mismatches, viral serologic test results, and initial immunosuppression. OUTCOMES OPTN-reported or Medicare claims-based PTLD diagnosis, recipient and graft survival after OPTN-reported PTLD diagnosis. MEASUREMENTS Adjusted HRs for PTLD diagnosis estimated using a Cox proportional hazards model; probability of survival free of all-cause graft failure estimated using the Kaplan-Meier method. RESULTS The incidence rate of PTLD during the first posttransplant year was 2-fold higher in Medicare claims (0.46/100 patient-years; 95% CI, 0.39-0.53) than in OPTN data (0.22/100 patient-years; 95% CI, 0.17-0.27). Factors associated with increased rates of PTLD included older age, white race (vs African American), induction with T-cell-depleting antibodies, Epstein-Barr virus seronegativity at the time of transplant, and cytomegalovirus seronegativity at the time of transplant. The adjusted risk of death with graft function was 17.5 (95% CI, 14.3-21.4) times higher after a report of PTLD, and the risk of death-censored graft failure was 5.5 (95% CI, 3.9-7.7) times higher. LIMITATIONS Shortcomings inherent in large databases, including inconsistencies in patient follow-up, reporting, and coding practices by transplant centers; insufficient registry data to analyze acute rejection episodes and antirejection treatment; no available data for potential effects of different types of PTLD treatment on patient outcomes. CONCLUSIONS Despite the limitations of data collected by registries, PTLD clearly is an important complication; both mortality and death-censored graft failure increase after PTLD.