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PurposeABBV-383, a B-cell maturation antigen × CD3 T-cell engaging bispecific antibody, has demonstrated promising results in an ongoing first-in-human phase I study (ClinicalTrials.gov identifier: NCT03933735) in patients with relapsed/refractory multiple myeloma (RRMM). Herein, we report safety and efficacy outcomes of this phase I dose escalation/expansion study.MethodsPatients with RRMM (≥ three prior lines including a proteasome inhibitor, an immunomodulatory drug, and an anti-CD38 monoclonal antibody) were eligible. ABBV-383 was administered intravenously over 1-2 hours once every 3 weeks, without any step dosing. A 3 + 3 design with backfilling for dose escalation was used (intrapatient escalation to highest safe dose permitted) followed by initiation of dose expansion.ResultsAs of January 8, 2022, 124 patients (dose escalation [0.025-120 mg], n = 73; dose expansion [60 mg], n = 51) have received ABBV-383; median age was 68 years (range, 35-92 years). The most common hematologic treatment-emergent adverse events (TEAEs) were neutropenia (all grades: 37%) and anemia (29%). The most common nonhematologic TEAEs were cytokine release syndrome (57%) and fatigue (30%). Seven deaths from TEAEs were reported with all considered unrelated to study drug by the investigator. For all efficacy-evaluable patients (n = 122; all doses), the objective response rate (ORR) was 57% and very good partial response (VGPR) or better (≥ VGPR) rate was 43%. In the 60 mg dose expansion cohort (n = 49), the ORR and ≥ VGPR rates were 59% and 39%, respectively; and in the ≥ 40 mg dose escalation plus dose expansion cohorts (n = 79) were 68% and 54%, respectively.ConclusionABBV-383 in patients with RRMM was well tolerated with an ORR of 68% at doses ≥ 40 mg. This novel therapy's promising preliminary antitumor activity in heavily pretreated patients warrants further clinical evaluation.

ABBV-184, a novel survivin peptide-targeting T-cell receptor (TCR)/anti-CD3 bispecific protein, demonstrated preclinical T-cell activation and cytotoxicity toward HLA-A2:01-positive tumor lines. This first-in-human trial evaluated ABBV-184 monotherapy in patients with acute myeloid leukemia (AML) and non-small cell lung cancer (NSCLC). This phase 1 multicenter, open-label, dose escalation trial (NCT04272203) enrolled adult patients with relapsed/refractory AML or NSCLC with an HLA-A2:01 restricted genotype. Patients received ABBV-184 at 0.07 ug/kg initially, with 2- to 3-fold dose increases. The primary objective was determining the ABBV-184 recommended phase 2 dose. Secondary objectives included safety, tolerability, pharmacokinetics, and immunogenicity assessments. Fifteen patients enrolled in the dose escalation (8 AML and 7 NSCLC). ABBV-184 doses ranged from 0.07 mg/kg–0.7 µg/kg, with a half-life of approximately 13–29 hours. Transient cytokine increases were observed at all dose levels, and in patients with NSCLC, transient peripheral blood lymphocyte decreases were observed. The most frequently reported treatment-emergent adverse events (TEAEs) were anemia, diarrhea, and headache. Grade 1–2 infusion-related reaction (IRR) and cytokine release syndrome (CRS) TEAEs were reported. ABBV-184 was well tolerated and demonstrated preliminary evidence of CD3 engagement with transient cytokine increases and peripheral lymphocyte decreases. NCT04272203 [ABSTRACT FROM AUTHOR]

Minimal residual disease (MRD) is an important emerging clinical end point in chronic lymphocytic leukemia (CLL). The objective of this research was to develop an integrated mechanistic model to evaluate the impact of venetoclax‐rituximab combination therapy on MRD kinetics. Using data from 435 patients with relapsed or refractory CLL, an integrated model was developed and validated that accounted for venetoclax dosing and pharmacokinetics, rituximab treatment, absolute lymphocyte count, and blood and bone marrow (BM) MRD data. Simulations of venetoclax‐rituximab (six cycles) combination predicted the proportion (90% confidence interval) of patients with BM MRD below 10−4 to be 57% (54–61%) and 63% (59–67%) at 12 and 24 months of treatment, respectively. Continued venetoclax treatment to 48 months only increased the predicted rate of negative BM MRD to 66% (63–70%). These results indicate that treatment with venetoclax‐rituximab combination for a finite 2‐year period would nearly maximize the rate of negative BM MRD (< 10−4). Preliminary clinical data agree with these predictions and more long‐term follow‐up data are awaited to confirm the same. [ABSTRACT FROM AUTHOR]

Exposure–response relationships from a phase 1b (M13-365) and phase 3 (MURANO) study were investigated to assess benefit/risk of venetoclax 400 mg daily plus rituximab in relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL). Dose intensities were summarized by tertiles of predicted venetoclax steady-state average concentrations based on nominal venetoclax dose (CmeanSS,nominal) for tolerability; exposure–safety analyses used logistic regression. Exposure–progression-free survival (PFS) relationships were assessed using MURANO data, with CmeanSS,nominal as a grouping factor. Covariates were demographics, geographic region, study, baseline disease characteristics, ECOG performance status, responsiveness to prior therapy, and chromosomal abnormalities. There was no significant effect of covariates on grade ≥3 neutropenia/infection or PFS, and no relationship between venetoclax exposure and these endpoints, or venetoclax or rituximab dose intensity. These results support the recommended venetoclax 400 mg daily dose in combination with rituximab in patients with R/R CLL or small lymphocytic leukemia. [ABSTRACT FROM AUTHOR]

Exposure-response analyses were performed for a venetoclax monotherapy study in 106 patients with varying subtypes of non-Hodgkin lymphoma (NHL) (NCT01328626). Logistic regression, time-to-event, and progression-free survival (PFS) analyses were used to evaluate the relationship between venetoclax exposure, NHL subtype and response, PFS, or occurrence of serious adverse events. Trends for small increases in the probability of response with increasing venetoclax exposures were identified, and became more evident when assessed by NHL subtype. Trends in exposure-PFS were shown for the mantle cell lymphoma (MCL) subtype, but not other subtypes. There was no increase in the probability of experiencing a serious adverse event with increasing exposure. Overall, the results indicate that venetoclax doses of 800-1200 mg as a single agent may be appropriate to maximize efficacy in MCL, follicular lymphoma, and diffuse large B-cell lymphoma subtypes with no expected negative impact on safety. [ABSTRACT FROM AUTHOR]

Demonstration of clinical effectiveness of a non-Hodgkin's lymphoma (NHL) treatment generally involves determination of progression-free survival (PFS). However, the long evaluation time of PFS limits its utility to make timely decisions in drug development. Therefore, the objective of this analysis was to determine the relationship between response rates and median PFS in NHL. A database was systematically developed from 513 identified NHL trials reported from 1996 to 2015. Potential predictors of the relationship between response rates and PFS were evaluated, including age, sex, treatment, percentage of treatment-naïve patients, and subtype of NHL. Seventy-three trials involving 86 cohorts were included in the meta-analysis. Linear regression analysis using logit of response rates and logarithm of median PFS indicated that the correlation between overall response rate (ORR) and median PFS was higher (R2  = 0.70) when compared to that of complete response (CR) rate and median PFS (R2  = 0.57). Furthermore, the correlation was improved with the addition of percentage of treatment-naïve patients and percentage of patients with follicular lymphoma (FL) (P < .005) between ORR and median PFS (R2  = 0.78), and between CR rate and median PFS relationship (R2  = 0.74). Treatment was not found to alter this relationship. In summary, ORR is as good as CR rate in predicting median PFS. Moreover, longer median PFS is expected in the trials including treatment-naïve and/or FL patients at a given ORR/CR rate. The determined relationship can be used to project the median PFS based on ORR or CR rate. [ABSTRACT FROM AUTHOR]

Venetoclax is indicated at a dosage of 400 mg daily (QD) for the treatment of patients with chronic lymphocytic leukemia (CLL) with 17p deletion who have received at least 1 prior therapy. Ongoing trials are evaluating venetoclax in combination with CD20 targeting monoclonal antibodies, such as rituximab. The objective of this research was to characterize the relationship between venetoclax exposures and progression-free survival (PFS) and to evaluate the effect of rituximab coadministration on PFS in patients with relapsed or refractory (R/R) CLL/small lymphocytic lymphoma (SLL). A total of 323 patients from 3 clinical studies of venetoclax, with and without rituximab coadministration, were pooled for the analyses. A time-variant relative risk survival model was used to relate plasma venetoclax concentrations and rituximab administration to PFS. Demographics and baseline disease characteristics were evaluated for their effect on PFS. A concentration-dependent effect of venetoclax on PFS and a prolonged synergistic effect of 6 cycles of concomitant rituximab were identified. The 17p deletion chromosomal aberration was not identified to affect the PFS of patients treated with venetoclax. A venetoclax dose of 400 mg daily QD was estimated to result in a substantial median PFS of 1.8 years (95% confidence interval [CI], 1.7-2.1), whereas the addition of 6 cycles of rituximab was estimated to increase the median PFS to 3.9 years (95% CI, 2.8-5.6). The analysis demonstrates a concentration-dependent effect of venetoclax on PFS and also a synergistic effect with rituximab. Combining venetoclax with the CD20 targeting monoclonal antibody rituximab in R/R CLL/SLL patients provides substantial synergistic benefit compared with increasing the venetoclax monotherapy dose. [ABSTRACT FROM AUTHOR]