Efficacy and Safety of the BiTE Antibody Blinatumomab in Chinese Adult Subjects With Relapsed/Refractory B-precursor Acute Lymphoblastic Leukemia (ALL)

A CR is defined as having ≤ 5% blasts in the bone marrow, no evidence of disease, and full recovery of peripheral blood counts (platelets \> 100,000/μL, and absolute neutrophil count \[ANC\] \> 1,000/μL). CRh\* is defined as ≤ 5% blasts in the bone marrow, no evidence of disease and partial recovery of peripheral blood counts: platelets \> 50,000/μl, and ANC \> 500/μl. CR/CRh\* rate is defined as the percentage of participants who achieve CR/CRh\* within 2 cycles of treatment with blinatumomab. Participants without response assessment were accounted for in the denominator when calculating the response rate, ie, these participants were counted as non-responders. The interim analysis was to become the primary analysis by meeting pre-specified efficacy and safety criteria based on an O'Brien-Fleming alpha spending function with the critical boundary 42.2%. Results for both the interim and final analysis are reported.

Time frame: Within 2 cycles of treatment (12 weeks)

Population: All enrolled participants who received any infusion of blinatumomab. The interim analysis was based on the first 90 participants who had a chance to complete ≥ 2 cycles of blinatumomab and the safety follow-up visit.

The 100-day mortality rate after allogeneic HSCT was defined as the percentage of participants having died up to 100 days after allogeneic HSCT estimated using the estimated time to death in percent calculated by Kaplan-Meier methods. Participants still alive alive were censored on the last documented visit date or the date of the last phone contact when the patient was last known to have been alive.

Time frame: 100 days after HSCT

Population: Participants who received any infusion of blinatumomab with a CR/CRh\* response who underwent alloHSCT while in remission. The interim analysis was based on the first 90 participants who had a chance to complete ≥ 2 cycles of blinatumomab and the safety follow-up visit, achieved CR/CRh\* and underwent alloHSCT while in remission.

Relapse-free survival time was calculated from the first onset of CR/CRh\* within the first 2 cycles until the documented hematological relapse, extra-medullary disease, or death due to any cause, whichever occurred first. Participants who were still alive and relapse-free were censored at the date of last disease assessment. Months were calculated as days from the first onset of CR/CRh\* within the 2 cycles until the documented hematological relapse/extra-medullary disease/death/censor date, divided by 30.5. Results for both the interim and final analysis are reported.

Time frame: Interim Analysis: From first onset of CR/CRh* to the data cutoff date of 12 April 2019; maximum time on follow-up for RFS was 12.4 months. Final Analysis: From first onset of CR/CRh* to end of study; maximum time on follow-up for RFS was 18.1 months.

Population: Enrolled participants who received any infusion of blinatumomab who achieved CR/CRh\* during the first 2 cycles. The interim analysis was based on the first 90 participants who had a chance to complete ≥ 2 cycles of blinatumomab and the safety follow-up visit and who achieved CR/CRh\* during the first 2 cycles.

Overall survival time was calculated from the time of first infusion of blinatumomab until death due to any cause. Participants still alive were censored at the date last known to be alive up until the data cut-off date (interim analysis) or end of study date (final analysis). Months are calculated as days from the first treatment to death/censor date, divided by 30.5. Results for both the interim and final analysis are reported.

Time frame: Interim analysis: From first dose of blinatumomab to the data cutoff date of 12 April 2019; maximum time on follow-up for OS was 14.7 months. Final analysis: From first dose of blinatumomab to end of study; maximum time on follow-up for OS was 25.7 months

Population: All enrolled participants who received any infusion of blinatumomab. The interim analysis was based on the first 90 participants who had a chance to complete ≥ 2 cycles of blinatumomab and the safety follow-up visit.

The European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-C30 (EORTC QLQ-C30) is a 30-question tool used to assess the overall quality of life in cancer patients. It consists of 15 domains: 1 global health status (GHS) scale, 5 functional scales, and 9 symptom scales/items. The GHS is reported in this outcome. For the GHS, scores range from 0 to 100 with a high score indicating better global health status/functioning. A ≥ 10-point decrease from baseline indicates a deterioration in quality of life. Months are calculated from start of blinatumomab date to deterioration/censor date, divided by 30.5.

Time frame: EORTC QLQ C30 was completed on days 1, 8, 15, and 29 during Cycle 1; days 1, 15, and 29 during cycle 2 and each consolidation cycle, and at the SFU visit (30 days after last dose).

Population: Participants who received blinatumomab treatment and had baseline and ≥ 1 postbaseline result for EORTC QLQ-C30 GHS.~The interim analysis was based on the first 90 participants who had a chance to complete ≥ 2 cycles of blinatumomab and the safety follow-up visit who had a baseline and ≥ 1 postbaseline result for EORTC QLQ-C30 GHS.

Adverse events (AEs) were evaluated for severity according to the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE), version 4.03, as follows: Grade 1 - Mild AE; Grade 2 - Moderate AE; Grade 3 - Severe AE; Grade 4 - Life-threatening or disabling AE; Grade 5 - Death. An AE was considered serious if it resulted in death, was life-threatening, required or prolonged inpatient hospitalization, resulted in persistent or significant incapacity or substantial disruption to conduct normal life functions, was a congenital anomaly or birth defect or was a medically important condition.

Time frame: From day 1 to 30 days after last infusion of blinatumomab; median (min, max) treatment duration was 30.9 (1, 142) days.

Population: All enrolled participants who received any infusion of blinatumomab.

Adverse events (AEs) were evaluated for severity according to the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE), version 4.03, as follows: Grade 1 - Mild AE; Grade 2 - Moderate AE; Grade 3 - Severe AE; Grade 4 - Life-threatening or disabling AE; Grade 5 - Death. The investigator used medical judgment to determine if there was a causal relationship (ie, related, unrelated) between an adverse event and blinatumomab. An AE was considered serious if it resulted in death, was life-threatening, required or prolonged inpatient hospitalization, resulted in persistent or significant incapacity or substantial disruption to conduct normal life functions, was a congenital anomaly or birth defect or was a medically important condition.

Time frame: From day 1 to 30 days after last infusion of blinatumomab; median (min, max) treatment duration was 30.9 (1, 142) days.

Population: All enrolled participants who received any infusion of blinatumomab.

Anti-blinatumomab binding antibodies were evaluated with a validated blinatumomab anti-drug antibody assay.

Time frame: Cycle 2, day 29 (after the completion of Cycle 2) and the SFU visit (30 days after last dose of blinatumomab)

Population: Enrolled participants who received any infusion of blinatumomab with available post-baseline antibody results.

Percentage of participants who underwent allogenic HSCT while in remission among those who responded to treatment by achieving CR/CRh\* during treatment. Results for both the interim and final analysis are reported.

Time frame: Interim analysis: Up to the data cutoff date of 12 April 2019; maximum time on follow-up was 14.7 months. Final analysis: Up to the end of study; maximum time on follow-up was 25.7 months.

Population: Enrolled participants who received any infusion of blinatumomab who achieved CR/CRh\* during treatment. The interim analysis was based on the first 90 participants who had a chance to complete ≥ 2 cycles of blinatumomab and the safety follow-up visit and who achieved CR/CRh\* during treatment.

CRi is defined as ≤ 5% blasts in the bone marrow, no evidence of disease and incomplete recovery of peripheral blood counts: platelets \> 100,000/μl or ANC \> 1,000/μl (but not both). CR/CRh\*/CRi rate is defined as the percentage of participants who achieve CR/CRh\*/CRi within 2 cycles of treatment with blinatumomab. Participants without response assessment were accounted for in the denominator when calculating the response rate, ie, these participants were counted as non-responders. Results for both the interim and final analysis are reported.

Time frame: Within 2 cycles of treatment (12 weeks)

Population: All enrolled participants who received any infusion of blinatumomab. The interim analysis was based on the first 90 participants who had a chance to complete ≥ 2 cycles of blinatumomab and the safety follow-up visit.

A CR is defined as having ≤ 5% blasts in the bone marrow, no evidence of disease, and full recovery of peripheral blood counts (platelets \> 100,000/μL, and absolute neutrophil count \[ANC\] \> 1,000/μL). CR rate is defined as the percentage of participants who achieved CR within 2 cycles of treatment with blinatumomab. Participants without response assessment were accounted for in the denominator when calculating the response rate, ie, these participants were counted as non-responders. Results for both the interim and final analysis are reported.

Time frame: Within 2 cycles of treatment (12 weeks)

Population: All enrolled participants who received any infusion of blinatumomab. The interim analysis was based on the first 90 participants who had a chance to complete ≥ 2 cycles of blinatumomab and the safety follow-up visit.

The detection of MRD (the presence of a low number of leukemic cells that are not detectable by light microscopy) after induction therapy and/or consolidation therapy is an independent prognostic factor for poor outcome of ALL. Participants highly responsive to chemotherapy with a MRD-level \< 1 × 10\^-4 leukemic cells detectable by flow cytometry induced by induction treatment, have a favorable prognosis. MRD response is defined as \< 1 ×10\^-4 leukemic cells detectable as measured by flow cytometry. MRD complete response is defined as having no detectable leukemic cells by flow cytometry. Results for both the interim and final analysis are reported.

Time frame: Within 2 cycles of treatment (12 weeks)

Population: Participants who received any infusion of blinatumomab who achieved CR/CRh\* within 2 cycles and had evaluable MRD assessment. The interim analysis was based on the first 90 participants who had a chance to complete ≥ 2 cycles of blinatumomab and the safety follow-up visit who achieved CR/CRh\* within 2 cycles and had evaluable MRD assessment.

Systemic clearance (CL) calculated as the average CL value during cycle 1 and cycle 2, where CL = infusion rate (μg/hour) / Css

Time frame: Cycle 1: Days 2, 15 and 29; Cycle 2: Days 2, 15 and 29 (approximately study days 44, 57 and 71)

Population: Participants in the pharmacokinetic analysis set with available CL data at at least one post-baseline time point; data below the lower limit of quantification and from participants who did not receive the specified doses were excluded.

Blinatumomab serum concentration was quantified using a validated enzyme- linked immunosorbent assay (ELISA). The lower limit of quantification (LLOQ) was 50 pg/mL. Blinatumomab serum steady-state concentrations (Css) was summarized as the average of the observed concentrations collected after 24 hours from the start of continuous IV infusion for each dose level. Cycle 1 day 2 values represent Css for the initial dose of blinatumomab (9 µg/day). Values collected from other time points were used to calculate Css of 28 µg/day dose in their respective cycles.

Time frame: Cycle 1: Days 2, 15, and 29; Cycle 2: Days 2, 15, and 29 (approximately study days 44, 57, and 71)

Population: Pharmacokinetic analysis set consisting of all participants who received blinatumomab and had at least one PK sample collected. The number of participants analyzed for each time point reflects participants with available Css data; data below the lower limit of quantification and from subjects who did not receive the specified doses were excluded.

Terminal half-life (t1/2,z) calculated as t1/2,z = ln(2)/lambda-z, where lambda-z was the first-order rate constant estimated via linear regression of the terminal log-linear decay phase from day 29 post-end of infusion collections.

Time frame: Cycle 1 Day 29: prior to end of infusion and after the end of infusion at 3 hours and 6 hours

Population: Participants in the pharmacokinetic analysis set with sufficient data on cycle 1 day 29 to calculate half-life. Data below the lower limit of quantification and from participants who did not receive the specified doses were excluded.

The volume of distribution (Vz) was calculated as Vz = CL/lambda-z, where lambda-z was the first-order rate constant estimated based on cycle 1 day 29 collections via linear regression of the terminal log-linear decay phase as determined from the noncompartmental analysis and where CL was the CL averaged over multiple cycles. Volume of distribution was estimated for participants who have sufficient evaluable PK data.

Time frame: Cycle 1: Days 2, 15 and 29; Cycle 2: Days 2, 15, and 29 (approximately study days 44, 57 and 71)

Population: Participants in the pharmacokinetic analysis set with sufficient data to calculate volume of distribution. Data below the lower limit of quantification and from participants who did not receive the specified doses were excluded.