Stout, Frank

Abstract Background: Autoimmune hemolytic anemia (AIHA) is a rare autoimmune disease characterized by hemolysis mediated by autoantibodies directed against red blood cells (RBC). AIHA is classified as either warm (60-70%), or cold agglutinin disease (CAD, 20-25%), depending upon the temperature at which the autoantibodies show maximum binding. Warm AIHA is mediated by warm reactive autoantibodies, which are usually of the immunoglobulin G class (IgG). Almost 90% of CAD is medicated by monoclonal antibodies of IgM class. The diagnosis of wAIHA or CAD is based on the presence of hemolytic anemia, signs of hemolysis, and a positive direct antiglobulin test (DAT) for IgG or IgM, and/or complement C3. Complement plays an important role in warm antibody AIHA. When erythrocytes are heavily coated with immunoglobulin, the amount of antigen-antibody complex can be sufficient for binding complement protein complex C1, thereby activating the classical complement pathway. CAD is almost entirely a complement-dependent disorder. Cold antibodies (IgM) temporarily bind to the RBC membrane, activate complement, and deposit complement factor C3 on the cell surface. These C3-coated RBCs are cleared slowly by the macrophages of the liver through extravascular hemolysis. Less frequently, the complete complement cascade is activated on the cell surface, resulting in the insertion of membrane attack complex C5b to C9 and intravascular hemolysis. Therefore, treatment with inhibitors of complement cascade may halt or at least attenuate acute complement mediated hemolysis in AIHA patients and improve recovery of RBC destruction. Aims: This Phase 2, open-label study is being conducted in the US and Italy to assess the safety, tolerability, efficacy, and PK of multiple subcutaneous (SC) doses of APL-2 administered daily in subjects with wAIHA or CAD. Methods: Patients with primary AIHA are eligible. Patients are required to have hemoglobin (Hb) levels <11 g/L, signs and symptoms of hemolysis, and a positive direct antiglobulin test (DAT) for IgG or IgM, and/or complement C3. The study will recruit 12 subjects with wAIHA and 12 subjects with CAD. APL-2 270 mg/d or 360 mg/d will be administered for 48 weeks. Efficacy is assessed by change from baseline in Hb, transfusion requirements, reticulocytes, lactate dehydrogenase (LDH), haptoglobin, bilirubin, and FACIT fatigue score. Endpoints will be assessed at Weeks 8, 12, 44, and 48. Results: 2 subjects with CAD (Subject 1: 270 mg/d; Subject 2: 360 mg/d) have been treated for at least 8 weeks and up to 12 weeks; 2 subjects with wAIHA (Subject 3: 270 mg/d; Subject 4: 360 mg/d) have been treated for at least 4 weeks. Subject 1 screened with Hb (NR 13.5 g/dL-17.5g/dL) of 10.0 g/dL and reported an increase to 13.0 g/dL at Week 12, with reticulocyte (NR 30-100 10^9/L) reduction from 99.6 10^9/L at Week 2 to 56.34 10^9/L at Week 8 (screening/baseline values not available). Subject 2 had baseline Hb of 7.9 g/dL and reported an increase to 13.6 g/dL at Week 8, with reticulocyte reduction from 154.34 10^9/L at baseline to 67 10^9/L at Week 8. Subject 3 had baseline Hb of 8.0 g/dL and reported an increase to 11.2 g/dL at Week 4, with reticulocyte reduction from 223.44 10^9/L at baseline to 27.12 10^9/L at Week 4. Subject 4 did not show signs of haematological improvement by Week 4, and the principal investigator decided to discontinue the subject at Day 42. Subject 1 had LDH levels within the normal range (100-200 I/U) at screening and remained normal through the study. Subjects 2 reported a baseline LDH of 339 I/U with a reduction to within NR to 107 I/U at Week 8. Subject 3 reported a baseline LDH of 235 I/U, which was also reduced to within NR at Week 4 to 123 I/U. Subject 1 had consistent indirect bilirubin (NR 0.2-0.7 mg/dL) through the study with a baseline value of 1.5 mg/dL and a Week 12 value of 1.4 mg/dL. Subject 2 had a reduction in indirect bilirubin with a baseline value of 1.3 mg/dL and a Week 8 value of 0.5 mg/dL.To date, APL-2 has generally been well-tolerated. No significant infections have been observed. Summary/Conclusions: Interim results demonstrate that systemic inhibition of C3 with APL-2 has demonstrated positive trends in haematological parameters in patients with wAIHA and CAD as early as Week 4. To date, APL-2 has been safe and well tolerated. The study is ongoing and will enroll up to 12 subjects with wAIHA and 12 subjects with CAD. Disclosures Grossi: Apellis Pharmaceuticals: Employment, Equity Ownership. Gertz:spectrum: Consultancy, Honoraria; Medscape: Consultancy; Amgen: Consultancy; Physicians Education Resource: Consultancy; Apellis: Consultancy; Teva: Consultancy; Alnylam: Honoraria; Prothena: Honoraria; janssen: Consultancy; Ionis: Honoraria; Research to Practice: Consultancy; celgene: Consultancy; Abbvie: Consultancy; annexon: Consultancy. Deschatelets:Apellis Pharmaceuticals: Employment, Equity Ownership. Hamdani:Apellis Pharmaceuticals: Employment, Equity Ownership. Stout:Apellis Pharmaceuticals: Employment, Equity Ownership. Francois:Apellis Pharmaceuticals: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees.

Background:Autoimmune haemolytic anaemia (AIHA) is characterized by haemolysis mediated by autoantibodies directed against red blood cells (RBCs). Warm antibody (wAIHA; 60%>70%) and cold agglutinin disease (CAD; 20%>25%) subclasses are defined by the immunoglobulin (Ig) isotype involved and its thermal optimum for binding RBCs. wAIHA is mediated by IgG while 90% of CAD is mediated by IgM isotypes. CAD and wAIHA outcomes can be life‐threatening, but no therapies are approved. Complement C3b deposition on RBCs plays a central role in AIHA, accelerating phagocytosis in the liver and/or spleen (extravascular haemolysis) and forming membrane attack complexes (intravascular haemolysis). By blocking formation of C3b, APL‐2, a cyclic peptide, has potential as a novel therapeutic for AIHA.Aims:To assess whether inhibiting complement C3 with daily subcutaneous (SC) doses of APL‐2 (270 mg/day or 360 mg/day) prevents intra‐ and extravascular haemolysis in AIHA subjects, reducing anaemia associated signs and symptoms.Methods:Subjects with primary AIHA were eligible for this Ph 2 open‐label study to assess the safety, tolerability, efficacy, and pharmacokinetics of APL‐2. Subjects had haemoglobin (Hb) levels < 11 g/dL, signs of haemolysis, and a positive direct agglutinin test (DAT) for IgG and/or complement C3. Twenty‐four subjects (13 CAD, 11 wAIHA) were recruited and will be treated with APL‐2 for 48 weeks. Efficacy was assessed by change from baseline in Hb, transfusion requirements, absolute reticulocyte counts (ARC), lactate dehydrogenase (LDH), haptoglobin, indirect bilirubin (INDBIL), and Functional Assessment of Illness Therapy (FACIT) fatigue score. Data are reported after 16 weeks (Day 112).Results:Two of 13 CAD subjects withdrew; 7 of 11 remaining subjects reached Day 112. Mean Hb (standard error [SE]) increased from 8.9 (0.4) [n = 13] to 11.6 (0.5) [n = 7] g/dL, and mean LDH, ARC, and INDBIL returned within normal range. Mean FACIT scores (SE) increased 9.9 (3.4) points from baseline. Two subjects had pre‐study and 1 had on‐study transfusions (normalized to 112 days). All 13 CAD experienced ≥1 treatment‐emergent adverse event (TEAE), mainly Grade 1–2 and unrelated. Four subjects reported 10 unrelated serious adverse events (SAEs) (6 SAEs in 1 subject). Three subjects experienced 3 unrelated Grade 3 TEAEs (pneumonia, dyspnoea, hypertension); 1 subject reported 2 unrelated Grade 4 TEAEs (high calcium, high creatinine) and withdrew.Eight of 11 wAIHA subjects were DATmonoC3+ and 3 were DATmonoC3‐. Two of 3 DATmonoC3‐ withdrew for lack of response and efficacy data are reported for 8 DATmonoC3+ subjects. Six of these reached Day 112. Mean Hb (SE) increased from 9.2 (0.3) [n = 8] to 10.8 (0.5) [n = 6] g/dL, and mean ARC and INDBIL returned within normal. Mean FACIT scores (SE) increased 2.7 (2.8) points from baseline. One subject had pre‐study and 2 had on‐study transfusions (normalized to 112 days). Ten of 11 wAIHA (C3+ and C3‐) experienced ≥1 TEAE, mainly Grade 1–2 and unrelated. Five subjects reported 8 unrelated SAEs. Five subjects experienced 13 unrelated Grade 3 TEAEs (oral squamous cell carcinoma, haemolytic flare, purpura, acute kidney injury, dyspnoea, chest pain); 1 subject reported 1 unrelated Grade 4 TEAE (haemolytic flare) and withdrew. Six‐month data for 10 CAD and 6 wAIHA C3+ is planned for June 2019.Summary/Conclusion:APL‐2 increases Hb values in CAD and wAIHA C3+ within the first weeks of treatment with sustained benefit with longer exposure. APL‐2 reduces intra‐ and extravascular haemolysis shown by reductions in LDH, INDBIL, and ARC. APL‐2 appears to be safe and well‐tolerated.