Fostamatinib for the Treatment of Warm Antibody Autoimmune Hemolytic Anemia (wAIHA): A Phase 3, Randomized, Double-Blind, Placebo-Controlled, Global Study

Background. Warm antibody autoimmune hemolytic anemia (wAIHA) is a rare disorder that can be potentially serious. In wAIHA, autoantibodies react with protein antigens on red blood cells (RBCs) at body temperature, leading to RBC phagocytosis and destruction by Fcg receptor-bearing macrophages in a spleen tyrosine kinase (SYK) dependent signaling pathway (see figure). Fostamatinib is a potent oral SYK inhibitor, approved for the treatment of chronic immune thrombocytopenia (ITP). Fostamatinib prevents platelet destruction in ITP through inhibition of SYK-dependent platelet phagocytosis by Fcγ receptor-bearing macrophages. Fostamatinib was evaluated in a phase 2, open-label, multicenter study (NCT02612558) for the treatment of wAIHA. Results of the study demonstrated that 11 of 25 (44%) patients had markedly improved hemoglobin (Hgb) levels after fostamatinib treatment. Adverse events (AEs) were consistent with those in the fostamatinib safety database of >4000 patients across multiple diseases. Based on the results of the phase 2 study, a phase 3 randomized, double-blind, placebo-controlled, global study (NCT03764618) was initiated to investigate the safety and efficacy of fostamatinib in patients with wAIHA. The phase 3 study began enrolling patients this year and intends to enroll approximately 90 patients at 103 sites in 22 countries across North America, Europe, and Australia. This is the first randomized, double-blind, placebo-controlled, phase 3 study to evaluate a SYK inhibitor for the treatment of wAIHA (see diagram). Study Design and Methods Inclusion Criteria include: Age ≥18;Diagnosis of primary or secondary wAIHA (documented by an IgG or IgA positive direct antiglobulin test [DAT]);failure of ≥1 prior treatment for wAIHA;Haptoglobin <LLN (lower limit of normal) or total bilirubin >ULN (upper limit of normal) or lactate dehydrogenase (LDH) >ULN;Baseline hemoglobin level ≤9 g/dL or, if hemoglobin is >9 g/dL to <10 g/dL, subject must be on a permitted wAIHA treatment AND have symptoms associated with anemia. Exclusion Criteria include: Presence of other forms of AIHA;Uncontrolled or insufficiently controlled hypertension;Neutrophil count <1,000/µL,Platelet count <30,000/μL (unless patient has Evans syndrome);Transaminase levels >1.5 x ULN. Eligible patients will be randomized 1:1 to fostamatinib or placebo for 24 weeks. Randomization will be stratified by concomitant steroid use and severity of anemia at baseline. The starting dose of fostamatinib is 100 mg BID and will be increased to 150 mg BID at Week 4, based on tolerability. The dose may be reduced in the event of dose-limiting AEs. At screening, patients may continue selected concurrent wAIHA therapies including steroids (maximum of 2 therapies) throughout the 24-week study period. A steroid taper protocol will allow reduced used of steroids in patients who have a hemoglobin response. Rescue therapy will be allowed as needed. Patients who complete the phase 3 study can rollover to an open-label extension study. The efficacy endpoints will include hemoglobin response, defined as a hemoglobin level ≥10 g/dL with a ≥2 g/dL increase from baseline (Day 1) in the absence of rescue therapy; duration of hemoglobin response; and the need for wAIHA rescue treatment. The safety endpoints will include the incidence of adverse events. Patients will be evaluated in the clinic, including safety and laboratory assessments, at two-week intervals. Statistics: A sample size of 90 subjects (randomized 1:1) would be required to provide 80% power to detect a difference in the response between the active and placebo groups using the Cochran-Mantel-Haenszel test at a two-sided significance level of 0.05 (based on results of the phase 2 study). The response rate will be compared between groups using a chi-square test adjusted for randomization stratification factors. Current enrollment status: As of July 2, 2020, 83 sites are open to screening (subject to local regulations about the COVID-19 pandemic), and 43 patients have been randomized. Most patients (88%) had primary wAIHA, 12% had secondary disease including chronic lymphocytic leukemia, monoclonal B cell lymphocytosis, scleroderma, smoldering Waldenström's macroglobulinemia, and systemic lupus erythematosus in 1 patient each. The median age at baseline is 61 years (range 28-87), and 63% are female. Figure Disclosures Cooper: Amgen: Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau. Numerof:Rigel: Current Employment, Current equity holder in publicly-traded company. Tong:Rigel: Current Employment, Current equity holder in publicly-traded company. Kuter:Incyte: Consultancy, Honoraria; Genzyme: Consultancy, Honoraria; Immunovant: Consultancy, Honoraria; Momenta: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Dova: Consultancy, Honoraria; Merck Sharp Dohme: Consultancy, Honoraria; UCB: Consultancy, Honoraria; Up-To-Date: Consultancy, Honoraria, Patents & Royalties; Zafgen: Consultancy, Honoraria; Sanofi (Genzyme): Consultancy, Honoraria; Shionogi: Consultancy, Honoraria; Shire: Consultancy, Honoraria; Principia: Consultancy, Research Funding; Protalix Biotherapeutics: Consultancy; Shionogi: Consultancy; Actelion (Syntimmune): Consultancy, Honoraria, Other: Travel Expenses, Research Funding; Daiichi Sankyo: Consultancy, Honoraria; Agios: Consultancy, Honoraria, Other: Travel Expenses, Research Funding; Alnylam: Consultancy, Honoraria, Other: Travel Expenses, Research Funding; Amgen: Consultancy, Honoraria, Other: Travel Expenses, Research Funding; Argenx: Consultancy, Honoraria, Other: Travel Expenses, Research Funding; Bristol-Myers Squibb: Consultancy, Honoraria, Other: Travel Expenses, Research Funding; Immunovant: 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; Protalex: Consultancy, Honoraria, Other, Research Funding; Rigel: Consultancy, Honoraria, Other, Research Funding; Takeda (Bioverativ): Consultancy, Honoraria, Other, Research Funding; Protalex: Consultancy, Honoraria, Research Funding; Kyowa-Kirin: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Platelet Disorder Support Association: Consultancy, Honoraria.

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A Multinational, Open-Label Phase 2 Study Of Ruxolitinib In Asian Patients (Pts) With Primary Myelofibrosis (PMF), Post–Polycythemia Vera MF (PPV-MF), Or Post–Essential Thrombocythemia MF (PET-MF)

Blood ◽

10.1182/blood.v122.21.4086.4086 ◽

2013 ◽

Vol 122 (21) ◽

pp. 4086-4086

Author(s):

Chul Won Jung ◽

Lee-Yung Shih ◽

Zhijian Xiao ◽

Jie Jin ◽

Hsin-An Hou ◽

...

Keyword(s):

Primary Endpoint ◽

Research Funding ◽

Phase 2 ◽

Spleen Volume ◽

Open Label ◽

Phase 3 ◽

Phase 2 Study ◽

Open Label Phase ◽

Large Phase ◽

Grade 3

Abstract Background Ruxolitinib is a potent JAK1/JAK2 inhibitor that has demonstrated rapid and durable reductions in splenomegaly, improved MF-related symptoms and quality of life (QoL), and prolonged survival in 2 phase 3 studies comparing ruxolitinib with placebo (COMFORT-I) and best available therapy (COMFORT-II). However, no clinical trial in pts with MF had been conducted in Asian countries, and only a limited number of Asian pts or healthy volunteers had been enrolled in any ruxolitinib study. Methods This study was an open-label phase 2 study evaluating ruxolitinib in Asian pts with PMF, PPV-MF, or PET-MF who had palpable splenomegaly ≥ 5 cm below the costal margin and intermediate-2– or high-risk MF by the International Working Group for Myelofibrosis Research and Treatment (IWG-MRT) criteria. Pts received starting doses of ruxolitinib 15 or 20 mg twice daily (bid) based on baseline platelet count (100-200 or > 200 × 109/L, respectively); dose adjustments balancing safety and efficacy were allowed to titrate each pt to their most appropriate dose. The primary endpoint was met if the proportion of pts achieving ≥ 35% reduction in spleen volume from baseline at week 24 was ≥ 27.5% as measured by MRI/CT. Symptomatic response was assessed as a secondary endpoint using the 7-day modified MF Symptom Assessment Form (MFSAF) v2.0 total symptom score (TSS) and European Organisation for Research and Treatment of Cancer QoL Questionnaire Core 30 (EORTC QLQ-C30). The study was conducted in China (n = 63), Japan (n = 30), Korea (n = 17), and Taiwan (n = 10). The data cutoff date for this analysis was 7 June 2013. Results Overall, 120 pts were enrolled (PMF, n = 80; PPV-MF, n = 21; PET-MF, n = 19), and their baseline characteristics were as follows: median age, 61 years (range, 25-80 years); 51.7% female; 69.2% intermediate-2 and 30.8% high risk by IWG-MRT criteria; median palpable spleen size, 15 cm (range, 5-45 cm); median spleen volume, 2159 cm3; 55.8% of pts had prior exposure to hydroxyurea. The median follow-up was 8.44 months; 22.5% of pts discontinued treatment, primarily for adverse events (AEs; 9.2%) and disease progression (7.5%). The median duration of treatment was 8.44 months (range, 0.5-21.7 months), and the median daily dose was 20.64 mg/day in the 15 mg bid group (n = 46) and 36.11 mg/day in the 20 mg bid group (n = 74). All pts were evaluable for achievement of the primary endpoint, 101 pts remained on study and were evaluable at week 24, and 96 pts had nonzero scores on the MFSAF-TSS and were evaluable for a reduction from baseline. Most pts who had assessments at week 24 (91% [92/101]) had a reduction from baseline in spleen volume (Figure). The study met the primary endpoint, with 31.7% (38/120) of all pts achieving ≥ 35% reduction from baseline at week 24. Overall, 38.3% (46/120) of pts achieved ≥ 35% reduction from baseline in spleen volume at any time on study. As measured by the 7-day MFSAF, 49% (47/96) of pts achieved ≥ 50% reduction from baseline in TSS (median reduction, 47.2%). Pts experienced an improvement from baseline at week 24 in EORTC global health status/QoL (mean change, 5.2). The most common nonhematologic AEs (≥ 10%) regardless of relationship to study medication included diarrhea (25.8%), upper respiratory tract infection (17.5%), ALT level increased (15.0%), pyrexia (15.0%), AST level increased (13.3%), cough (11.7%), herpes zoster infection (11.7%), nasopharyngitis (10.8%), constipation (10.0%), gamma-glutamyl transferase level increased (10.0%), and headache (10.0%), and most were grade 1/2. Serious AEs were reported for 24.2% of pts, and 65.8% of all pts had grade 3/4 AEs. The most common new or worsening laboratory abnormalities were low hemoglobin (all grade 3, 55.7%), low lymphocyte (grade 3/4, 19.5%), low platelet (grade 3/4, 15.3%), and low ANC (grade 3/4, 7.6%) levels. AEs observed in this study were consistent with those observed in the 2 large phase 3 COMFORT studies. Six pts (5%) died on treatment or within 30 days of discontinuation. Summary/conclusions Findings from this study demonstrated that ruxolitinib was relatively well tolerated in Asian pts with MF and provided substantial reductions in splenomegaly and modest improvements in MF-associated symptoms. The AEs observed with ruxolitinib treatment in this study are consistent with those observed in the large phase 3 COMFORT studies, and there were no new AEs associated with ruxolitinib in Asian pts with MF. Disclosures: Okamoto: Novartis: Honoraria, Research Funding. Sirulnik:Novartis: Employment. Ruiz:Novartis: Employment. Amagasaki:Novartis: Employment. Ito:Novartis: Employment. Akashi:Novartis: Membership on an entity’s Board of Directors or advisory committees, Research Funding.

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A Phase 2, Open-Label, Ascending Dose Study of Ker-050 for the Treatment of Anemia in Patients with Very Low, Low, or Intermediate Risk Myelodysplastic Syndromes

Blood ◽

10.1182/blood-2021-147335 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 3675-3675

Author(s):

David M Ross ◽

Alejandro Arbelaez ◽

Lynette C.Y. Chee ◽

Chun Yew Fong ◽

Devendra Hiwase ◽

...

Keyword(s):

Board Of Directors ◽

Research Funding ◽

Study Drug ◽

Phase 2 ◽

Publicly Traded ◽

Open Label ◽

Advisory Committees ◽

Maximum Increase ◽

Phase 2 Study ◽

Dose Levels

Abstract Background: Myelodysplastic syndromes (MDS) are characterized by ineffective hematopoiesis leading to cytopenias, including anemia and thrombocytopenia. KER-050, a modified activin receptor type IIA inhibitor, is designed to target transforming growth factor-β ligands, including activin A. In preclinical studies, KER-050 promoted the maturation of progenitors across the full spectrum of erythropoiesis and thrombopoiesis and elicited bone anabolic effects. In a Phase 1 study in healthy participants, KER-050 treatment resulted in robust and sustained increases in reticulocytes (RETs), hemoglobin (HGB), and platelets. Increases in the bone formation marker bone specific alkaline phosphatase were also observed. Here we report results of an ongoing Phase 2 study to evaluate whether KER-050 provides therapeutic benefit in MDS patients with anemia. Aims: Evaluate safety, tolerability, pharmacodynamics and efficacy of ascending doses of KER-050 in participants with MDS in an open-label, 2-part Phase 2 study. Methods: IPSS-R very low-to-intermediate risk MDS patients (both RS+ and non-RS) with anemia (HGB <10g/dL or requiring RBC transfusions) are enrolled. In Part 1, ascending dose cohorts receive KER-050 subcutaneously every 4 weeks for 4 doses starting at 0.75mg/kg until a recommended Part 2 dose is determined. Part 2 dose expansion will begin following Part 1, with treatment extended to 2 years. Safety endpoints include incidence of adverse events (AEs); erythroid efficacy endpoints (≥8 weeks duration) include rates of transfusion independence (TI) in transfused participants, reduction in RBC transfusions by ≥4 units or ≥50% reduction in high transfusion burden participants (HTB) and HGB increase ≥1.5g/dL in non-transfused (NT) and low transfusion burden (LTB) participants. Results are reported for efficacy-evaluable participants in cohorts 1 and 2 of Part 1 dose escalation, defined as having ≥8 weeks of HGB and transfusion data. Results: At data cut-off (July 10, 2021) with median follow-up of 140 days (range 1 to 169 days), 17 participants had received ≥1 dose of KER-050 across 3 dose levels: 0.75 mg/kg, 1.5 mg/kg and 2.5 mg/kg. Baseline characteristics are described in Table 1. No related serious AEs, dose-limiting toxicities, or dose modifications were reported. One participant developed grade 2 maculopapular rash after the first dose which was considered treatment related, resolved and did not recur with subsequent doses. No other related AEs were reported. Two discontinued study drug prior to end of treatment: 1 due to participant decision, 1 due to death unrelated to study drug. None developed high risk MDS or AML. In 10 efficacy-evaluable participants, overall erythroid response rate was 60% (n=6/10). 33% (n=1/3) NT participants had a HGB increase of ≥1.5g/dL sustained ≥ 8 weeks. 5 of 7 transfused participants (71%) (n=1/2 LTB and n=4/5 HTB; n=2/3 non-RS and n=3/4 RS+) had erythroid responses sustained ≥8 weeks (range 8-20 weeks, ongoing) and 57% (n=4/7) achieved TI (Figure 1, Panel A). Maximum increase from baseline in RETs observed in transfused responders (TR) (n=5) was 24.6 x10 9/L (mean), range 10.5- 41.6 x10 9/L from day 1-29 with increases in RETs seen after each dose (Panel B). Maximum reduction in serum ferritin in TR was 40.4% (mean), range 10-66%, and maximum increase in soluble transferrin receptor (sTfR) was 52.8% (mean), range 29.8-116.4%. Increases in platelets were observed in TR (Panel C). Mean baseline platelet count for TR was 234 x10 9/L (range 104-401 x10 9/L), and maximum increase from baseline was 130 x10 9/L (mean), range 32-235 x10 9/L. No participants required dose reduction due to thrombocytosis. Summary: Erythroid responses have been observed in RS+ and non-RS MDS patients including reduction in transfusion burden at the initial dose levels. Observed increases in RETs and sTfR and observed decreases in ferritin suggest that KER-050 treatment is potentially associated with increased erythropoiesis. Increases in platelets have been observed in TR. These data support the potential of KER-050 as a treatment for multilineage cytopenias in MDS by potentially targeting multiple stages of hematopoiesis. As of data cut-off, KER-050 has been well tolerated. Dose escalation is ongoing in this Phase 2 study of anemic patients with MDS; data from planned cohorts from Part 1 will be presented. Part 2 dose expansion phase is expected to initiate prior to the meeting. Figure 1 Figure 1. Disclosures Ross: Bristol Myers Squib: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Keros Therapeutics: Consultancy, Honoraria. Arbelaez: Amgen: Other: Travel, Accommodations, Expenses. Chee: Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees. Fong: AbbVie: Consultancy; Amgen: Consultancy; Astellas: Consultancy, Research Funding; Bristol Myers Squibb: Consultancy; Novartis: Consultancy, Speakers Bureau; Phizer: Consultancy; Novotech: Honoraria; Specialised Therapeutics: Honoraria. Hiwase: Novartis: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees. Wight: Jannsen: Honoraria, Other: Travel subsidies; Abbvie: Honoraria, Other: Travel subsidies. Rovaldi: Keros Therapeutics: Current equity holder in publicly-traded company. Furutani: Keros Therapeutics: Current Employment, Current equity holder in publicly-traded company. Gaggi: Keros Therapeutics: Current Employment, Current equity holder in publicly-traded company. Jiang: Keros Therapeutics: Current Employment, Current holder of stock options in a privately-held company. Lachey: Keros Therapeutics: Current Employment, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees. Natarajan: Keros Therapeutics: Current Employment, Current equity holder in publicly-traded company. Ordonez: Keros Therapeutics: Current Employment, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees.

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Mitapivat (AG-348) in Adults with Pyruvate Kinase Deficiency Who Are Not Regularly Transfused: A Phase 3, Randomized, Multicenter, Double-Blind, Placebo-Controlled Study (ACTIVATE) in Progress

Blood ◽

10.1182/blood-2019-123100 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 4791-4791

Author(s):

Eduard J. van Beers ◽

Malia P. Judge ◽

Lei Hua ◽

Chris Mix

Keyword(s):

Research Funding ◽

Fixed Dose ◽

Controlled Study ◽

Open Label ◽

Employment Equity ◽

Phase 3 ◽

Double Blind ◽

Double Blind Placebo ◽

Dose Period ◽

Equity Ownership

Background: Pyruvate kinase (PK) deficiency is an under-recognized hereditary disease that causes lifelong hemolytic anemia. Mutations in the PKLR gene lead to reduced red cell PK (PK-R) enzyme activity, resulting in defective glycolysis and decreased lifespan of red blood cells. Mitapivat (AG-348) is a novel, first-in-class, oral, small-molecule allosteric activator of PK-R under clinical testing as the first targeted, disease-altering therapy for PK deficiency. The DRIVE PK study (NCT02476916; a phase 2, open-label, dose-ranging trial in adults with PK deficiency who are not regularly transfused) demonstrated that twice-daily (BID) dosing with mitapivat for >6 months was well tolerated and induced rapid, substantial, and durable responses (Grace et al. ASH 2017). Of 52 enrolled subjects, 26 (50%) had a maximum hemoglobin (Hb) increase of >1 g/dL in the 6-month treatment period. Among these 26 subjects, the mean maximum Hb increase was 3.4 g/dL, and 25 (96%) had ≥1 missense PKLR mutation. Based on these findings, mitapivat has entered phase 3 development in PK deficiency. The design of the ongoing phase 3 ACTIVATE study and its extension study are reported here, with an update on country/site activation. Methods: ACTIVATE is a phase 3, multicenter, randomized, double-blind, placebo-controlled study (NCT03548220) evaluating the efficacy and safety of mitapivat. Adults with PK deficiency who are not regularly transfused (≤4 transfusion episodes in the previous year and no transfusions in the prior 3 months) will be randomized in a 1:1 ratio to mitapivat (administered orally, BID) or matched placebo. Additional criteria include baseline Hb ≤10.0 g/dL and adequate organ function. Subjects who are homozygous for the R479H mutation or have 2 non-missense mutations (without the presence of another missense mutation) in PKLR will be excluded. The study consists of a screening period of up to 42 days, a 12-week dose optimization period, and a 12-week fixed-dose period (Figure). During the dose optimization period, mitapivat or matched placebo are titrated up to each subject's individually optimized dose, with an initial dose of 5 mg BID for all subjects and potentially 2 sequential dose increases (from 5 to 20 mg BID and from 20 to 50 mg BID), depending on safety and Hb change. The primary endpoint is the Hb response, defined as the proportion of subjects who achieve an increase of ≥1.5 g/dL in Hb sustained over at least 2 of the last 3 visits in the fixed-dose period. The average change in Hb during the fixed-dose period is considered a key secondary endpoint to further evaluate the magnitude of the treatment effect. Other secondary efficacy endpoints, such as markers of hemolysis and hematopoietic activity, will be evaluated to support the efficacy evaluation and confirm the mechanism of action, and safety is included as a secondary objective and endpoint. Two questionnaires, one specifically designed to measure the signs and symptoms of PK deficiency and the other designed to evaluate their impact on patients' lives, are also included for their validation and to further evaluate the efficacy of the treatment. All subjects who complete the study have the opportunity to enroll in an open-label extension study (NCT03853798) in which all participants will receive mitapivat for up to 192 weeks. An independent data monitoring committee will review the study data periodically and provide safety oversight. The ACTIVATE study is currently ongoing. Disclosures van Beers: Novartis: Consultancy, Research Funding; Pfizer: Research Funding; RR Mechatronics: Research Funding; Agios Pharmaceuticals, Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding. Judge:Agios: Employment, Equity Ownership. Hua:Agios Pharmaceuticals, Inc.: Employment, Equity Ownership. Mix:Agios: Employment, Equity Ownership.

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Mavorixafor, an Oral CXCR4 Antagonist, for Treatment of Patients with WHIM Syndrome: Results from the Long-Term Extension of the Open-Label Phase 2 Study

Blood ◽

10.1182/blood-2021-145759 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 1121-1121

Author(s):

David C. Dale ◽

Frank Caleb Firkin ◽

Audrey Anna Bolyard ◽

Weihua Tang ◽

Honghua Jiang ◽

...

Keyword(s):

Research Funding ◽

Term Treatment ◽

Phase 2 ◽

Publicly Traded ◽

Open Label ◽

Whim Syndrome ◽

Patient Interviews ◽

Phase 2 Study ◽

Long Term Treatment

Abstract Background: WHIM (Warts, Hypogammaglobulinemia, Infections, and Myelokathexis) syndrome is a rare, autosomal-dominant primary immunodeficiency. Gain-of-function (GOF) mutations in the CXCR4 gene are the most common cause of WHIM syndrome, manifesting as panleukopenia with severe neutropenia, lymphopenia, and monocytopenia, recurrent bacterial infections, unusual susceptibility to human papillomavirus infections with intractable mucocutaneous warts, and increased risk of malignancy (McDermott DH, et al. Immunol Rev. 2019;2878:91-102). Mavorixafor is an investigational, small-molecule, selective antagonist of the CXCR4 receptor being developed as an oral, once-daily (QD) treatment for patients with WHIM syndrome (Dale DC, et al. Blood. 2020;136(26):2994-3003). Objective: We present an update on the clinical outcomes of patients with WHIM syndrome who continued in the long-term extension of the phase 2 study, highlighting long-term safety and efficacy. Methods: A long-term extension is ongoing as part of the open-label, prospective, dose-escalation, phase 2 study evaluating the safety and efficacy of mavorixafor (NCT03005327) in adults with WHIM syndrome. Individuals with a pathogenic GOF CXCR4 mutation and absolute neutrophil count ≤400/μL and/or absolute lymphocyte count ≤650/μL were included. All provided written informed consent. The primary objectives were to evaluate safety and tolerability and assess safe dosage. Exploratory efficacy end points included changes in infection rates, number of cutaneous warts, and white blood cell counts, compared to baseline. Researchers completed detailed interviews of 4 participants continuing in the study to assess their overall study experience and perceived treatment effects. Results: Five of 8 patients in the dose-finding phase 2 study entered into the long-term extension (LTE); median treatment duration was 148.4 weeks. One patient left the LTE because of study fatigue, and all 5 patients had dose escalation to 400 mg oral QD as of May 2021. As of the November 2020 data cutoff, annualized infection rates decreased from 5.6/year at study baseline to 2.2/year at 40 months' treatment, providing evidence of persistent reduction of infections over time. At doses of 300 and 400mg QD (n=7), the mean time above threshold for ANC and ALC were 12.7 hours (SD ± 9.8) and 16.9 hours (SD ± 5.9) compared to 2.1 hours (SD ± 3.3) and 11.5 hours (SD ± 5.9) at doses ≤200 mg QD, respectively. One patient experienced a 79% reduction in warts. Safety data review at May 2021 showed that there were 12 minor treatment-emergent adverse events (grade 1) with long-term treatment (46 months), no treatment-related infections of grade 3 or higher, no treatment-related serious adverse events, and no clinically significant laboratory abnormalities with mavorixafor treatment. Patient interviews revealed that all 4 LTE participants experienced good tolerability of mavorixafor and decreased frequency, severity, and duration of infections and decreased hospital/doctor visits. Three of 4 participants reported previous need for prophylactic treatment to prevent infection of minor wounds, but with mavorixafor, minor wounds healed without infection or need for prophylaxis. The mechanism of action of mavorixafor was of interest to 3 of 4 participants, who found it important that treatment address the underlying cause of disease, not simply the symptoms. Two participants reported a QOL improvement, and the other 2 reported that WHIM syndrome never affected their QOL Conclusion: Ongoing long-term treatment of adults with WHIM syndrome with mavorixafor 300 to 400mg shows durable increase in neutrophils and lymphocytes and sustained improvements in infections and warts. Detailed patient interviews for patient global impression of changes are consistent with sustained clinical benefit of long-term treatment. Mavorixafor has the potential to be a safe, effective, and long-term therapy targeting the underlying cause of WHIM syndrome. A global phase 3 registrational study is ongoing. Disclosures Dale: X4 Pharmaceuticals: Consultancy, Honoraria, Research Funding. Firkin: X4 Pharmaceuticals: Research Funding. Bolyard: X4 Pharmaceuticals: Research Funding. Tang: X4 Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Jiang: X4 Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. MacLeod: X4 Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Cadavid: X4 Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Hu: X4 Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company.

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Magnetismm-3: An Open-Label, Multicenter, Non-Randomized Phase 2 Study of Elranatamab (PF-06863135) in Patients with Relapsed or Refractory Multiple Myeloma

Blood ◽

10.1182/blood-2021-152984 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 1674-1674

Author(s):

Alexander Lesokhin ◽

Shinsuke Iida ◽

Don Stevens ◽

Afshin Eli Gabayan ◽

Wei Dong Ma ◽

...

Keyword(s):

Board Of Directors ◽

Proteasome Inhibitor ◽

Research Funding ◽

Phase 2 ◽

Publicly Traded ◽

Open Label ◽

Advisory Committees ◽

Phase 2 Study ◽

Immunomodulatory Drug ◽

Randomized Phase 2

Abstract Background: Multiple myeloma (MM) is a hematological B-cell malignancy that remains incurable for most patients. Almost all patients, including those who initially respond to treatment, are expected to relapse and subsequently cycle through multiple lines of treatment. The addition of proteasome inhibitors, immunomodulatory drugs and monoclonal antibodies has improved patient outcomes; however, survival of patients after these agents is very poor and highlights an unmet medical need in the relapsed/refractory MM population. Elranatamab (PF-06863135) is a humanized bi-specific antibody that targets both BCMA-expressing MM cells and CD3-expressing T cells, with binding resulting in T-cell mediated cytotoxicity. Elranatamab preclinical studies have demonstrated anti-tumor activity and delayed tumor progression. A Phase 1 study, MagnetisMM-1 (ClinicalTrials.gov ID: NCT03269136), with the aim of characterizing the efficacy, safety, pharmacokinetics, and pharmacodynamics of elranatamab as single agent and in combination with immunomodulatory agents for patients with relapsed/refractory MM is ongoing. Study Design and Methods: MagnetisMM-3 is an open-label, multicenter, non-randomized, Phase 2 study to evaluate the efficacy and safety of elranatamab monotherapy in patients with relapsed/refractory MM who are refractory to at least one proteasome inhibitor, one immunomodulatory drug, and one anti-CD38 antibody (ClinicalTrials.gov ID: NCT04649359). Approximately 150 patients will be enrolled to one of two independent parallel cohorts: those naïve to BCMA-directed therapies (Cohort A) and those with previous exposure to BCMA-directed therapy (Cohort B). The primary endpoint is objective response rate, according to International Myeloma Working Group [IMWG] response criteria. Secondary endpoints include duration of response, cumulative complete response (CR) rate, duration of cumulative CR, progression-free survival, time to response, minimal residual disease negativity rate, overall survival, safety, plasma concentrations, and immunogenicity of elranatamab. Key inclusion criteria are age ≥18 years, MM diagnosis according to IMWG criteria and with measurable disease based on IMWG criteria as defined by at least 1 of the following: Serum M-protein ≥0.5 g/dL by SPEP, Urinary M-protein excretion ≥200 mg/24 hours by UPEP; Serum immunoglobulin free light chain ≥10 mg/dL (≥100 mg/L) and abnormal serum immunoglobulin kappa to lambda free light chain ratio (<0.26 or >1.65). Eligible patients should also have ECOG performance status ≤2, be refractory to at least one proteasome inhibitor, one immunomodulatory drug, and one anti-CD38 antibody and be relapsed/refractory to their last treatment regimen. Key exclusion criteria are smoldering MM, active plasma cell leukemia, amyloidosis, POEMS syndrome, active, uncontrolled bacterial, fungal or viral infections, stem cell transplant within 12 weeks of enrollment, any other active malignancy within 3 years prior to enrollment (except for adequately treated basal cell or squamous cell skin cancer, or carcinoma in situ), or having received previous administration of an investigational drug within 30 days or 5 half-lives (whichever is longer) of the first dose of elranatamab. This study is, or is planned to be, open at centers in the USA, Australia, Canada, Belgium, France, Germany, Japan, Poland, Spain, and the UK. Disclosures Lesokhin: Genetech: Research Funding; Serametrix, Inc: Patents & Royalties; pfizer: Consultancy, Research Funding; Behringer Ingelheim: Honoraria; Trillium Therapeutics: Consultancy; bristol myers squibb: Research Funding; Iteos: Consultancy; Janssen: Honoraria, Research Funding. Iida: Ono: Honoraria, Research Funding; Glaxo SmithKlein: Research Funding; Janssen: Honoraria, Research Funding; Abbvie: Research Funding; Chugai: Research Funding; Celgene: Honoraria, Research Funding; Sanofi: Honoraria, Research Funding; Takeda: Honoraria, Research Funding; Bristol-Myers Squibb: Research Funding; Daiichi Sankyo: Research Funding; Amgen: Research Funding. Ma: Pfizer Inc: Current Employment, Current equity holder in publicly-traded company. Sullivan: Pfizer Inc: Current Employment, Current equity holder in publicly-traded company. Raab: Janssen: Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy, Honoraria; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees; GSK: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Sanofi: Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Consultancy; Celgene: Membership on an entity's Board of Directors or advisory committees.

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