Neutrophil elastase as a versatile cleavage enzyme for activation of αvβ3 integrin-targeted small molecule drug conjugates with different payload classes in the tumor microenvironment

Introduction: The development of bioconjugates for the targeted delivery of anticancer agents is gaining momentum after recent success of antibody drug conjugates (ADCs) in the clinic. Smaller format conjugates may have several advantages including better tumor penetration; however, cellular uptake and trafficking may be substantially different from ADCs. To fully leverage the potential of small molecule drug conjugates (SMDCs) with potent binding molecules mediating tumor homing, novel linker chemistries susceptible for efficient extracellular activation and payload release in the tumor microenvironment (TME) need to be explored. Methods: We designed a novel class of SMDCs, which target αvβ3 integrins for tumor homing and are cleaved by neutrophil elastase (NE), a serine protease active in the TME. A peptidomimetic αvβ3 ligand was attached via optimized linkers composed of substrate peptide sequences of NE connected to different functional groups of various payload classes, such as camptothecins, monomethyl auristatin E, kinesin spindle protein inhibitors (KSPi) and cyclin-dependent kinase 9 inhibitors (CDK-9i). Results: NE-mediated cleavage was found compatible with the diverse linker attachments via hindered ester bonds, amide bonds and sulfoximide bonds. Efficient and traceless release of the respective payloads was demonstrated in biochemical assays. The newly designed SMDCs were highly stable in buffer as well as in rat and human plasma. Cytotoxicity of the SMDCs in cancer cell lines was clearly dependent on NE. IC50 values were in the nanomolar or sub-nanomolar range across several cancer cell lines reaching similar potencies as compared to the respective payloads only in the presence of NE. In vivo pharmacokinetics evaluating SMDC and free payload exposures in rat and particularly the robust efficacy with good tolerability in triple negative breast and small cell lung cancer murine models demonstrate the utility of this approach for selective delivery of payloads to the tumor. Discussion: These results highlight the broad scope of potential payloads and suitable conjugation chemistries paving the way for future SMDCs harnessing the safety features of targeted delivery approaches in combination with NE cleavage in the TME.

Enitociclib, a Selective CDK9 Inhibitor, Induces Complete Regression of MYC+ Lymphoma by Downregulation of RNA Polymerase II Mediated Transcription

Double-hit diffuse large B-cell lymphoma (DH-DLBCL) is an aggressive, and often refractory, type of B-cell non-Hodgkin lymphoma (NHL) characterized by rearrangements in MYC and BCL2. Cyclin-dependent kinase 9 (CDK9) regulates transcriptional elongation and activation of transcription factors, including MYC, making it a potential targeted approach for the treatment of MYC+ lymphomas. Enitociclib is a well-tolerated and clinically active CDK9 inhibitor leading to complete metabolic remissions in 2 of 7 patients with DH-DLBCL treated with once weekly 30 mg intravenous administration. Herein, we investigate the pharmacodynamic effect of CDK9 inhibition in preclinical models and in blood samples from patients [DH-DLBCL (n = 10) and MYC+ NHL (n = 5)] treated with 30 mg i.v. once weekly enitociclib. Enitociclib shows significant regulation of RNA polymerase II Ser2 phosphorylation in a MYC-amplified SU-DHL-4 cell line and depletion of MYC and antiapoptosis protein MCL1 in SU-DHL-4 and MYC-overexpressing SU-DHL-10 cell lines in vitro. Tumor growth inhibition reaching 0.5% of control treated SU-DHL-10 xenografts is achieved in vivo and MYC and MCL1 depletion as well as evidence of apoptosis activation after enitociclib treatment is demonstrated. An unbiased analysis of the genes affected by CDK9 inhibition in both cell lines demonstrates that RNA polymerase II and transcription pathways are primarily affected and novel enitociclib targets such as PHF23 and TP53RK are discovered. These findings are recapitulated in blood samples from enitociclib-treated patients; while MYC downregulation is most robust with enitociclib treatment, other CDK9-regulated targets may be MYC independent delivering a transcriptional downregulation via RNA polymerase II.

SIGNIFICANCE

MYC+ lymphomas are refractory to standard of care and novel treatments that downregulate MYC are needed. The utility of enitociclib, a selective CDK9 inhibitor in this patient population, is demonstrated in preclinical models and patients. Enitociclib inhibits RNA polymerase II function conferring a transcriptional shift and depletion of MYC and MCL1. Enitociclib intermittent dosing downregulates transcription factors including MYC, providing a therapeutic window for durable responses in patients with MYC+ lymphoma.

Discovery of VIP236, an αvβ3-Targeted Small-Molecule-Drug Conjugate with Neutrophil Elastase-Mediated Activation of 7-Ethyl Camptothecin Payload for Treatment of Solid Tumors

The emerging field of small-molecule-drug conjugates (SMDCs) using small-molecule biomarker-targeted compounds for tumor homing may provide new perspectives for targeted delivery. Here, for the first time, we disclose the structure and the synthesis of VIP236, an SMDC designed for the treatment of metastatic solid tumors by targeting αvβ3 integrins and extracellular cleavage of the 7-ethyl camptothecin payload by neutrophil elastase in the tumor microenvironment. Imaging studies in the Lewis lung mouse model using an elastase cleavable quenched substrate showed pronounced elastase activity in the tumor. Pharmacokinetics studies of VIP236 in tumor-bearing mice demonstrated high stability of the SMDC in plasma and high tumor accumulation of the cleaved payload. Studies in bile-duct-cannulated rats showed that biliary excretion of the unmodified conjugate is the primary route of elimination. Treatment- and time-dependent phosphorylation of H2AX, a marker of DNA damage downstream of topoisomerase 1 inhibition, verified the on-target activity of the payload cleaved from VIP236 in vivo. Treatment with VIP236 resulted in long-lasting tumor regression in subcutaneous patient-derived xenograft (PDX) models from patients with non-small-cell lung, colon, and renal cancer as well as in two orthotopic metastatic triple-negative breast cancer PDX models. In these models, a significant reduction of brain and lung metastases also was observed.

Abstract 2722: Synthesis and characterization of novel small molecule drug conjugates with different payloads designed to be released in tumor microenvironment by neutrophil elastase

The development of small molecule drug conjugates (SMDCs) is gaining momentum after the 2018 approval of the small molecule radioconjugate lutetium-177 vipivotide tetraxetan. In contrast to the use of antibodies for tumor homing, small molecule binding ligands may result in a better tumor penetration. Also the potential targets for ADCs are limited to internalizing antigens so the ADC can be trafficked to the lysosomes for release and activation of the payload. We sought new mechanisms for extracellular activation of SMDCs using enzymes, which are present in the tumor microenvironment (TME). For example, neutrophil elastase (NE) belongs to a family of serine proteases that degrades elastin and other extracellular matrix proteins. NE also contributes to cancer progression by enhancing tumor evasion and metastasis. NE expression and neutrophil tumor infiltration have been correlated with metastatic potential and poor prognosis. Previous studies have shown that NE efficiently cleaves and activates camptothecin conjugates by cleaving an ester bond1.

Here we describe the successful use of NE for efficient activation and traceless payload release from several unique and proprietary SMDCs. Binding molecules such as a peptidomimetic αvβ3 ligand were linked via appropriate spacers to substrate tripeptides of NE. The C-terminal end was directly attached to different functional groups at various payloads such as camptothecins (CPT), monomethyl auristatin E, kinesin spindle protein inhibitors, and CDK9 inhibitors. Hindered ester bonds, amide bonds, and sulfoximide bonds were found to be efficiently cleaved by NE; conversely, those linkages were highly stable in culture medium and in circulation. Consequently, respective SMDCs are not or are moderately cytotoxic when incubated alone with cancer cell lines. However, in the presence of NE, cytotoxicity of the SMDCs increases by two orders of magnitude to the low nanomolar or subnanomolar range across several cell lines reaching similar potency as the respective payloads alone. In PK studies in mouse, rat, and dog, the SMDC with a CPT payload, shows a half-life of 3.6, 8.3, and 4.2 h, respectively, and excellent stability in circulation over 24 hr with low exposure levels (<1% of SMDC) of cleaved payload detectable. In an MX1 triple-negative breast cancer xenograft model, tumor regressions were observed when the SMDC was administered in a 2 days on/5 days off schedule.

NE is capable of cleaving sterically hindered ester bonds, amides, and sulfoximides to release a variety of potent payloads from different SMDCs in a traceless manner. These molecules represents a versatile strategy for selective delivery of payloads to TME that does not require the tumor target to internalize.

1Lerchen HG, Stelte-Ludwig B, Kopitz C, et al. Cancers 2022

Citation Format: Hans-Georg Lerchen, Anne-Sophie Rebstock, Marieke Wiedmann, Beatrix Stelte-Ludwig, Harvey Wong, Dmitry Zubov, Raquel Izumi, Ahmed Hamdy. Synthesis and characterization of novel small molecule drug conjugates with different payloads designed to be released in tumor microenvironment by neutrophil elastase [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2722.

VIP152 is a selective CDK9 inhibitor with pre-clinical in vitro and in vivo efficacy in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is effectively treated with targeted therapies including Bruton tyrosine kinase inhibitors and BCL2 antagonists. When these become ineffective, treatment options are limited. Positive transcription elongation factor complex (P-TEFb), a heterodimeric protein complex composed of cyclin dependent kinase 9 (CDK9) and cyclin T1, functions to regulate short half-life transcripts by phosphorylation of RNA Polymerase II (POLII). These transcripts are frequently dysregulated in hematologic malignancies; however, therapies targeting inhibition of P-TEFb have not yet achieved approval for cancer treatment. VIP152 kinome profiling revealed CDK9 as the main enzyme inhibited at 100 nM, with over a 10-fold increase in potency compared with other inhibitors currently in development for this target. VIP152 induced cell death in CLL cell lines and primary patient samples. Transcriptome analysis revealed inhibition of RNA degradation through the AU-Rich Element (ARE) dysregulation. Mechanistically, VIP152 inhibits the assembly of P-TEFb onto the transcription machinery and disturbs binding partners. Finally, immune competent mice engrafted with CLL-like cells of Eµ-MTCP1 over-expressing mice and treated with VIP152 demonstrated reduced disease burden and improvement in overall survival compared to vehicle-treated mice. These data suggest that VIP152 is a highly selective inhibitor of CDK9 that represents an attractive new therapy for CLL.

Abstract 1859: VIP152, a selective CDK9 inhibitor, demonstrates sensitivity in gynecologic cell lines that are cisplatin sensitive or resistant and delivers in vivo antitumor efficacy

Background: The Myc transcription factor has a short half-life of 20-30 minutes (Ramsay et al. 1984) and oncogenic activation and transcriptional addiction leads to sustained levels of Myc, (Gabay et al. 2014). Mechanisms of activation include MYC gene amplification, mutation or rearrangement and have been reported to be prevalent in gynecologic malignancies, such as serous ovarian (39.2%), uterine (28.1%) and endometrial (19.5%) (https://www.cancer.gov/tcga). Since CDK9 phosphorylation of RNA polymerase II is required for transcription of Myc mRNA, we evaluate VIP152, a highly selective CDK9 inhibitor (Lücking et al 2021), to deliver antitumor responses in preclinical models of gynecologic malignancies.

Methods: Gynecologic cell lines were treated with 9 dose levels of VIP152 with DMSO and cisplatin as controls. IC50 were calculated using CellTiter-Glo luminescent cell viability assay after 72 hours treatment. A preliminary analysis of 19 cell lines was undertaken to determine whether response to VIP152 is associated with baseline mutation, gene expression, or copy number variation data. Monotherapy efficacy of VIP152 was evaluated in a cisplatin sensitive A2780 in vivo xenograft mouse model.

Results: Screening of gynecologic cell lines demonstrates a 3-log range of sensitivity with VIP152 IC50s ranging from 38-593nM. Simultaneous cisplatin screening identified sensitive and resistant cell lines in the same panel. Low VIP152 IC50s were observed in cell lines sensitive or resistant to cisplatin. Cell lines were assigned as sensitive and resistant based on the VIP152 IC50 values. Preliminary analysis suggests a gene signature could predict response to VIP152 in gynecologic malignancies. VIP152 was evaluated in an ovarian cancer A2780 in vivo xenograft model. Monotherapy treatment with 4 doses of VIP152 across 5 dose levels from 5- to 15-mg/kg weekly regimens provided increasing tumor growth inhibition compared with vehicle control.

Conclusions: VIP152 demonstrates sensitivity in gynecologic cell lines independent of cisplatin sensitivity. An interim gene signature that is associated with VIP152 sensitivity was defined and we plan to optimize this signature with a larger cell line panel. Dose-dependent tumor growth inhibition in an in vivo xenograft model is demonstrated. VIP152 is currently being evaluated in the clinic (ClinicalTrials.gov Identifiers: NCT02635672 and NCT04978779). References: Gabay et al. 2014. Cold Spring Harb Perspect Med. 4(6):a014241. Lücking et al. 2021. J Med Chem. 64(15):11651-11674. Ramsay et al. 1984. PNAS. 81(24):7742-7746.

Citation Format: Melanie M. Frigault, Hermes Garban, Joy M. Greer, Stuart Hwang, Raquel Izumi, Amy J. Johnson, Beatrix Stelte-Ludwig, Ahmed Hamdy. VIP152, a selective CDK9 inhibitor, demonstrates sensitivity in gynecologic cell lines that are cisplatin sensitive or resistant and delivers in vivo antitumor efficacy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1859.

The highly selective Bruton tyrosine kinase inhibitor acalabrutinib leaves macrophage phagocytosis intact

Not available.

First-in-human dose escalation study of cyclin-dependent kinase-9 inhibitor VIP152 in patients with advanced malignancies shows early signs of clinical efficacy

PURPOSE

To report on the first-in-human phase I study of VIP152 (NCT02635672), a potent and highly selective CDK9 inhibitor.

PATIENTS AND METHODS

Adults with solid tumors or aggressive non-Hodgkin lymphoma (NHL) who were refractory to or had exhausted all available therapies received VIP152 monotherapy as a 30-minute intravenous, once weekly infusion, as escalating doses (5, 10, 15, 22.5, or 30 mg in 21-day cycles) until the maximum tolerated dose (MTD) was determined.

RESULTS

Thirty-seven patients received {greater than or equal to} 1 VIP152 dose, with 30 mg identified as the MTD based on dose-limiting toxicity of grade 3/4 neutropenia. The most common adverse events were nausea and vomiting (75.7% and 56.8%, respectively), all of grade 1/2 severity. Of the most common events, Grade 3/4 events occurring in > 1 patient were neutropenia (22%), anemia (11%), abdominal pain (8%), increased alkaline phosphatase (8%), and hyponatremia (8%). Day 1 exposure for the MTD exceeded the predicted minimum therapeutic exposure and reproducibly achieved maximal pathway modulation; no accumulation occurred after multiple doses. Seven of 30 patients with solid tumors had stable disease (including 9.5 and 16.8 months in individual patients with pancreatic cancer and salivary gland cancer, respectively), and 2 of 7 patients with high-grade B-cell lymphoma with MYC and BCL2/BCL6 translocations (HGL) achieved durable complete metabolic remission (ongoing at study discontinuation, after 3.7 and 2.3 years of treatment).

CONCLUSION

VIP152 monotherapy, administered intravenously once weekly, demonstrated a favorable safety profile and evidence of clinical benefit in patients with advanced HGL and solid tumors.

A Small Molecule–Drug Conjugate (SMDC) Consisting of a Modified Camptothecin Payload Linked to an αVß3 Binder for the Treatment of Multiple Cancer Types

To improve tumor selectivity of cytotoxic agents, we designed VIP236, a small molecule–drug conjugate consisting of an αVβ3 integrin binder linked to a modified camptothecin payload (VIP126), which is released by the enzyme neutrophil elastase (NE) in the tumor microenvironment (TME). The tumor targeting and pharmacokinetics of VIP236 were studied in tumor-bearing mice by in vivo near-infrared imaging and by analyzing tumor and plasma samples. The efficacy of VIP236 was investigated in a panel of cancer cell lines in vitro, and in MX-1, NCI-H69, and SW480 murine xenograft models. Imaging studies with the αVβ3 binder demonstrated efficient tumor targeting. Administration of VIP126 via VIP236 resulted in a 10-fold improvement in the tumor/plasma ratio of VIP126 compared with VIP126 administered alone. Unlike SN38, VIP126 is not a substrate of P-gp and BCRP drug transporters. VIP236 presented strong cytotoxic activity in the presence of NE. VIP236 treatment resulted in tumor regressions and very good tolerability in all in vivo models tested. VIP236 represents a novel approach for delivering a potent cytotoxic agent by utilizing αVβ3 as a targeting moiety and NE in the TME to release the VIP126 payload—designed for high permeability and low efflux—directly into the tumor stroma.

Evaluation of the Pharmacokinetics and Safety of a Single Dose of Acalabrutinib in Subjects With Hepatic Impairment

Acalabrutinib received approval for treatment of adult patients with mantle cell lymphoma who received at least one prior therapy and adult patients with chronic lymphocytic leukemia or small lymphocytic lymphoma. This study investigated the impact of hepatic impairment (HI) on acalabrutinib PK and safety at a single 50-mg dose in fasted subjects. This study was divided into two studies: study 1, an open-label, parallel-group study in Child-Pugh Class A or B subjects and healthy subjects, and study 2, an open-label, parallel-group study in Child-Pugh Class C subjects and healthy subjects. Baseline characteristics and safety profiles were similar across groups. Acalabrutinib exposure (area under the curve [AUC]) increased slightly (1.90- and 1.48-fold) in subjects with mild (Child-Pugh Class A) and moderate (Child-Pugh Class B) HI compared with healthy subjects. In severe HI (Child-Pugh Class C), acalabrutinib exposure (AUC and maximum concentration [C_max ]) increased approximately 5.0-fold and 3.6-fold, respectively. Results were consistent across total and unbound exposures. Severe HI did not impact total/unbound metabolite (ACP-5862) exposures; metabolite to parent ratio decreased to 0.6 - 0.8 (versus 3.1 - 3.6 in healthy subjects). In summary, single oral dose of 50 mg acalabrutinib was safe and well tolerated in subjects with mild, moderate and severe HI and in healthy control subjects. In subjects with severe HI, mean acalabrutinib exposure increased by up to 5-fold and should be avoided. Acalabrutinib does not require dose adjustment in patients with mild or moderate HI. This article is protected by copyright. All rights reserved.

Acalabrutinib monotherapy for treatment of chronic lymphocytic leukaemia (ACE-CL-001): analysis of the Richter transformation cohort of an open-label, single-arm, phase 1-2 study

BACKGROUND

Patients with chronic lymphocytic leukaemia who progress to Richter transformation (diffuse large B-cell lymphoma morphology) have few therapeutic options. We analysed data from the Richter transformation cohort of a larger, ongoing, phase 1-2, single-arm study evaluating the safety and activity of the selective, irreversible Bruton's tyrosine kinase inhibitor acalabrutinib for the treatment of chronic lymphocytic leukaemia or small lymphocytic lymphoma.

METHODS

For this open-label, single-arm, phase 1-2 study, patients aged 18 years or older with biopsy-proven treatment-naive or previously treated diffuse large B-cell lymphoma (Richter transformation) or prolymphocytic leukaemia transformation (Eastern Cooperative Oncology Group performance status ≤2) were assigned to receive oral acalabrutinib 200 mg twice daily as monotherapy until disease progression or toxicity. Patients were enrolled across seven centres from four countries. Safety and pharmacokinetics were assessed as primary endpoints; secondary endpoints were overall response rate, duration of response, and progression-free survival. Safety was assessed in the all-treated population (patients who received ≥1 dose), and activity was assessed in the all-treated population (for progression-free survival) and efficacy-evaluable population (for response rate; patients in the all-treated population with ≥1 response assessment after the first dose). This trial is registered with ClinicalTrials.gov (NCT02029443).

FINDINGS

Between Sept 2, 2014, and April 25, 2016, 25 patients with Richter transformation were enrolled; 12 (48%) were male and 23 (92%) were White. As of data cutoff (March 1, 2021), two (8%) of 25 patients remained on acalabrutinib. The median time on study was 2·6 months (IQR 1·8-8·4). The most common adverse events (all grades) were diarrhoea (12 [48%] of 25 patients), headache (11 [44%]), and anaemia (eight [32%]). The most common grade 3-4 adverse events were neutropenia (seven [28%] of 25) and anaemia (five [20%]). The most common reason for treatment discontinuation was disease progression (17 [68%] of 25 patients). 11 (44%) deaths were reported within 30 days of the last acalabrutinib dose; none was considered treatment-related. Acalabrutinib was rapidly absorbed and eliminated, with similar day 1 and day 8 exposures. The overall response rate was 40·0% (95% CI 21·1-61·3), with two (8%) of 25 patients having a complete response and eight (32%) having a partial response; the median duration of response was 6·2 months (95% CI 0·3-14·8). Median progression-free survival in the overall cohort was 3·2 months (95% CI 1·8-4·0).

INTERPRETATION

Acalabrutinib appears to be generally well tolerated, although progression-free survival was relatively poor in this cohort of patients with Richter transformation. On the basis of these findings, the use of acalabrutinib monotherapy in this setting is limited; however, further assessment of acalabrutinib as part of combination-based regimens for patients with Richter transformation is warranted.

FUNDING

Acerta Pharma, a member of the AstraZeneca Group.

Acalabrutinib Versus Ibrutinib in Previously Treated Chronic Lymphocytic Leukemia: Results of the First Randomized Phase III Trial

PURPOSE

Among Bruton's tyrosine kinase inhibitors, acalabrutinib has greater selectivity than ibrutinib, which we hypothesized would improve continuous therapy tolerability. We conducted an open-label, randomized, noninferiority, phase III trial comparing acalabrutinib and ibrutinib in patients with chronic lymphocytic leukemia (CLL).

METHODS

Patients with previously treated CLL with centrally confirmed del(17)(p13.1) or del(11)(q22.3) were randomly assigned to oral acalabrutinib 100 mg twice daily or ibrutinib 420 mg once daily until progression or unacceptable toxicity. The primary end point was independent review committee-assessed noninferiority of progression-free survival (PFS).

RESULTS

Overall, 533 patients (acalabrutinib, n = 268; ibrutinib, n = 265) were randomly assigned. At the data cutoff, 124 (46.3%) acalabrutinib patients and 109 (41.1%) ibrutinib patients remained on treatment. After a median follow-up of 40.9 months, acalabrutinib was determined to be noninferior to ibrutinib with a median PFS of 38.4 months in both arms (95% CI acalabrutinib, 33.0 to 38.6 and ibrutinib, 33.0 to 41.6; hazard ratio: 1.00; 95% CI, 0.79 to 1.27). All-grade atrial fibrillation/atrial flutter incidence was significantly lower with acalabrutinib versus ibrutinib (9.4% v 16.0%; P = .02); among other selected secondary end points, grade 3 or higher infections (30.8% v 30.0%) and Richter transformations (3.8% v 4.9%) were comparable between groups and median overall survival was not reached in either arm (hazard ratio, 0.82; 95% CI, 0.59 to 1.15), with 63 (23.5%) deaths with acalabrutinib and 73 (27.5%) with ibrutinib. Treatment discontinuations because of adverse events occurred in 14.7% of acalabrutinib-treated patients and 21.3% of ibrutinib-treated patients.

CONCLUSION

In this first direct comparison of less versus more selective Bruton's tyrosine kinase inhibitors in CLL, acalabrutinib demonstrated noninferior PFS with fewer cardiovascular adverse events.

Phase II study of acalabrutinib in ibrutinib-intolerant patients with relapsed/refractory chronic lymphocytic leukemia

B-cell receptor signaling inhibition by targeting Bruton tyrosine kinase (BTK) is effective in treating chronic lymphocytic leukemia. The BTK inhibitor ibrutinib may be intolerable for some patients. Acalabrutinib is a more selective BTK inhibitor that may be better tolerated by patients who are intolerant to ibrutinib. A phase II study of acalabrutinib was conducted in patients with relapsed/refractory chronic lymphocytic leukemia who were ibrutinib-intolerant and had continued disease activity. Intolerance was defined as having discontinued ibrutinib due to persistent grade 3/4 adverse events or persistent/recurrent grade 2 adverse events despite dose modification/interruption. Patients received oral acalabrutinib 100 mg twice daily until disease progression or intolerance. Sixty patients were treated. The overall response rate to acalabrutinib was 73% and three patients (5%) achieved complete remission. At a median follow-up of 35 months, the median progression-free and overall survival were not reached; 24-month estimates were 72% and 81%, respectively. The most frequent adverse events with acalabrutinib were diarrhea (53%), headache (42%), contusion (40%), dizziness (33%), upper respiratory tract infection (33%), and cough (30%). The most common reasons for acalabrutinib discontinuation were progressive disease (23%) and adverse events (17%). Most patients with baseline samples (49/52; 94%) and all with on-treatment samples (3/3; 100%) had no detectable BTK and/or PLCG2 mutations. Acalabrutinib is effective and tolerable in most patients with relapsed/refractory chronic lymphocytic leukemia who are intolerant of ibrutinib. Acalabrutinib may be useful for patients who may benefit from BTK inhibitor therapy but are ibrutinib intolerant. ClinicalTrials.gov identifier: NCT02717611.

A phase 1/2 study of the combination of acalabrutinib and vistusertib in patients with relapsed/refractory B-cell malignancies

In a phase 1b study of acalabrutinib (a covalent Bruton tyrosine kinase (BTK) inhibitor) in combination with vistusertib (a dual mTORC1/2 inhibitor) in patients with relapsed/refractory diffuse large B-cell lymphoma (DLBCL), multiple ascending doses of the combination as intermittent or continuous schedules of vistusertib were evaluated. The overall response rate was 12% (3/25). The pharmacodynamic (PD) profile for acalabrutinib showed that BTK occupancy in all patients was >95%. In contrast, PD analysis for vistusertib showed variable inhibition of phosphorylated 4EBP1 (p4EBP1) without modulation of AKT phosphorylation (pAKT). The pharmacokinetic (PK)/PD relationship of vistusertib was direct for TORC1 inhibition (p4EBP1) but did not correlate with TORC2 inhibition (pAKT). Cell-of-origin subtyping or next-generation sequencing did not identify a subset of DLBCL patients with clinical benefit; however, circulating tumor DNA dynamics correlated with radiographic response. These data suggest that vistusertib does not modulate targets sufficiently to add to the clinical activity of acalabrutinib monotherapy. Clinicaltrials.gov identifier: NCT03205046.

Changing for the Better: Discovery of the Highly Potent and Selective CDK9 Inhibitor VIP152 Suitable for Once Weekly Intravenous Dosing for the Treatment of Cancer

Selective inhibition of exclusively transcription-regulating positive transcription elongation factor b/CDK9 is a promising new approach in cancer therapy. Starting from atuveciclib, the first selective CDK9 inhibitor to enter clinical development, lead optimization efforts aimed at identifying intravenously (iv) applicable CDK9 inhibitors with an improved therapeutic index led to the discovery of the highly potent and selective clinical candidate VIP152. The evaluation of various scaffold hops was instrumental in the identification of VIP152, which is characterized by the underexplored benzyl sulfoximine group. VIP152 exhibited the best preclinical overall profile in vitro and in vivo, including high efficacy and good tolerability in xenograft models in mice and rats upon once weekly iv administration. VIP152 has entered clinical trials for the treatment of cancer with promising longterm, durable monotherapy activity in double-hit diffuse large B-cell lymphoma patients.

Abstract 1314: A novel small molecule drug conjugate -avb3 integrin antagonist linked to a cytotoxic camptothecin derivative- for the treatment of multiple cancer types

To improve tumor selectivity of cytotoxic agents we designed small molecule drug conjugates leveraging two independent mechanisms of targeted delivery by utilizing an integrin binder for tumor homing and release of the active drug by proteases present in tumor stroma. Integrins are transmembrane receptors that mediate cell-extracellular matrix and cell-cell interaction. αvβ3 integrins in the tumor microenvironment are involved in critical events for tumor progression, cytotoxic therapy resistance and metastasis including angiogenesis, matrix remodeling and the recruitment of immune and inflammatory cells. Proteases in tumor stoma such as neutrophil elastase also contribute to cancer progression by enhancing tumor evasion and metastasis. The expectation is that small molecule drug conjugates could have better efficacy for solid tumors than antibody drug conjugates due to better tissue penetration. Following this rationale the small molecule drug conjugate is composed of a peptidomimetic αvβ3 integrin antagonist linked to a cytotoxic camptothecin derivative via a linker susceptible to cleavage by neutrophil elastase. Imaging studies with the αvβ3 antagonist conjugated with an IR-800 dye demonstrated efficient tumor targeting to 786-0 renal adenocarcinoma tumors, as compared with a weakly binding epimer used as a control conjugate. The targeted conjugate is highly stable in rat plasma and shows strong cytotoxic activity only in the presence of neutrophil elastase. The payload displays high cellular permeability and in contrast to SN38, the active metabolite of irinotecan, it is not a substrate of efflux transporters. The conjugate is highly efficacious in vivo effecting tumor regressions in SW480 (colon cancer), MX1 (breast cancer) and NCI-H69 (lung cancer) xenograft models with T/C ratios of 0.1, 0.03 and 0.06 (p<0.05 each, compared to vehicle control) respectively and it shows very good tolerability. Initial pharmacokinetic studies in tumor bearing mice demonstrate a more than 10-fold improved tumor/plasma ratio of free toxophore when administered as a conjugate as compared with direct administration of unconjugated toxophore. In summary, our results show potent, selective, in vivo anticancer activity against three solid tumor subtypes with a novel small molecule drug conjugate consisting of the conjugation of an integrin antagonist with a cytotoxic agent via a tailored linker enabling cleavage in tumor stroma.

Citation Format: Hans-Georg Lerchen, Beatrix Stelte-Ludwig, Charlotte Kopitz, Melanie Heroult, Dmitry Zubov, Joerg Willuda, Thomas Schlange, Antje Kahnert, Raquel Izumi, Ahmed Hamdy. A novel small molecule drug conjugate -avb3 integrin antagonist linked to a cytotoxic camptothecin derivative- for the treatment of multiple cancer types [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1314.

Acalabrutinib in treatment-naive chronic lymphocytic leukemia

Acalabrutinib has demonstrated significant efficacy and safety in relapsed chronic lymphocytic leukemia (CLL). Efficacy and safety of acalabrutinib monotherapy were evaluated in a treatment-naive CLL cohort of a single-arm phase 1/2 trial (ACE-CL-001). Adults were eligible for enrollment if chemotherapy was declined or deemed inappropriate due to comorbidities (N = 99). Patients had a median age of 64 years and 47% had Rai stage III/IV disease. Acalabrutinib was administered orally 200 mg once daily, or 100 mg twice daily until progression or intolerance. A total of 99 patients were treated; 57 (62%) had unmutated immunoglobulin heavy-chain variable gene, and 12 (18%) had TP53 aberrations. After median follow-up of 53 months, 85 patients remain on treatment; 14 discontinued treatment, mostly because of adverse events (AEs) (n = 6) or disease progression (n = 3). Overall response rate was 97% (90% partial response; 7% complete response), with similar outcomes among all prognostic subgroups. Because of improved trough BTK occupancy with twice-daily dosing, all patients were transitioned to 100 mg twice daily. Median duration of response (DOR) was not reached; 48-month DOR rate was 97% (95% confidence interval, 90-99). Serious AEs were reported in 38 patients (38%). AEs required discontinuation in 6 patients (6%) because of second primary cancers (n = 4) and infection (n = 2). Grade ≥3 events of special interest included infection (15%), hypertension (11%), bleeding events (3%), and atrial fibrillation (2%). Durable efficacy and long-term safety of acalabrutinib in this trial support its use in clinical management of symptomatic, untreated patients with CLL.

Safety and efficacy of VIP152, a CDK9 inhibitor, in patients with double-hit lymphoma (DHL)

7538

Background: PTEFb/CDK9-mediated transcription of short-lived anti-apoptotic survival proteins and oncogenes like MCL-1 and MYC plays a critical role in a variety of cancers. VIP152 (formerly BAY 1251152), a potent and highly selective CDK9 inhibitor, has been evaluated in a Phase 1 dose-escalation study in patients with advanced cancer. The maximum tolerated dose was 30 mg once weekly administered in consecutive 21-day cycles, based on neutropenia as the dose-limiting toxicity (JCO 2018;36:2507; NCT02635672). DHL is defined as dual rearrangement of the MYC gene and either the BCL2 or BCL6 genes; the resulting overexpression of MYC and BCL2/BCL6 make it particularly difficult to treat. Patients with DHL have a poor prognosis and no standard of care. Considering the impact of CDK9 inhibition on MYC, an exploratory cohort of patients with DHL was added to the study. Methods: Patients with refractory or relapsed DHL were eligible. VIP152 was administered once weekly as a 30-minute IV infusion on Days 1, 8 and 15 of a 21-day cycle. Tumor response was assessed according to the revised Cheson criteria (2007). Results: To date a total of 7 patients have been enrolled and were evaluable at the time of data cutoff (24NOV2020). The patients were mostly men (6/7 pts, 86%) with a median (range) age of 70 (58-84) years. All patients received ≥2 prior therapies, including 2 patients with bone marrow transplant. Three of 7 patients (29%) had ≥3 prior therapies. The median time on treatment was 22 days (range 8-1361 days). The most common adverse events of any grade were: constipation, fatigue, nausea (each 3/7 pts, 43%) and abdominal pain, diarrhea, lymphocyte count decrease, neutrophil count decrease, skin infection, tumor pain, and vomiting (each 2/7 pts, 29%). Most were Grade 1 and Grade 2. The Grade 3 adverse events were fatigue, lymphocyte count decrease, neutrophil count decrease (each 1/7 pts, 14%) and tumor pain (2/7 pts, 29%). One Grade 4 lymphocyte count decrease was reported. Two patients had a serious adverse event (Grade 3 syncope and Grade 3 tumor pain). Two patients had dosing held for an adverse event; however, no patient withdrew from treatment due to any adverse events. One death occurred due to disease progression. Pharmacodynamic biomarker analysis showed significant reduction of MYC, PCNA, and MCL-1 mRNA in all patients across multiple timepoints. Antitumor activity consisted of 2 complete metabolic responses in 7 patients (29%) based on investigator-assessed FDG-PET scans. Due to the COVID pandemic, the patients withdrew consent after 3.7 and 2.3 years, respectively, of treatment. Both patients were in complete metabolic response. Conclusions: VIP152 had a manageable safety profile, on-target pharmacodynamic activity and signs of durable monotherapy antitumor activity in patients with DHL. These encouraging results warrant further evaluation of VIP152 in patients with MYC-driven lymphoma and solid tumors. Clinical trial information: NCT02635672.

Pooled analysis of safety data from clinical trials evaluating acalabrutinib monotherapy in mature B-cell malignancies

Bruton tyrosine kinase (BTK) inhibition is an effective therapy for many B-cell malignancies. Acalabrutinib is a next-generation, potent, highly selective, covalent BTK inhibitor. To characterize acalabrutinib tolerability, we pooled safety data from 1040 patients with mature B-cell malignancies treated with acalabrutinib monotherapy in nine clinical studies (treatment-naïve: n = 366 [35%], relapsed/refractory: n = 674 [65%]; median [range] age: 67 [32-90] years; median [range] prior treatments: 1 [0-13]; median [range] duration of exposure: 24.6 [0.0-58.5] months). The most common adverse events (AEs) were headache (38%), diarrhea (37%), upper respiratory tract infection (22%), contusion (22%), nausea (22%), fatigue (21%), and cough (21%). Serious AEs (SAEs) occurred in 39% of patients; pneumonia (6%) was the only SAE that occurred in ≥2%. Deaths due to AEs occurred in 52 patients (5%); pneumonia (n = 8) was the only fatal AE to occur in ≥3 patients. AEs led to treatment discontinuation in 9%. Rates for the AEs of interest (all grades) included infections (67%), hemorrhages (46%), neutropenia (16%), anemia (14%), second primary malignancies (12%), thrombocytopenia (9%), hypertension (8%), and atrial fibrillation (4%). This pooled analysis confirmed acalabrutinib's tolerability and identified no newly emerging late toxicities, supporting acalabrutinib as a long-term treatment for patients with mature B-cell malignancies.

Effects of oligomeric proanthocyanidins (OPCs) of red wine to improve skin whitening and moisturizing in healthy women - a placebo-controlled randomized double-blind parallel group comparative study

OBJECTIVE

This study was undertaken to evaluate the effects of red wine from grapes oligomeric procyanidins (OPCs) intake on skin color and skin moisture in Japanese healthy women. The purpose of this study was to improve skin condition, with the primary endpoint set to improve sunburn by ultraviolet (UV) and the secondary endpoint set to improve dryness.

PATIENTS AND METHODS

A randomized, placebo-controlled, double-blind, parallel-group study was conducted on 100 subjects (30 to 59 years of age). They were administered a test beverage, including 200 mg of the red wine OPCs (the test beverage group) or a placebo beverage (the control beverage group) once a day for 12 weeks. The properties of facial skin were measured at 0 (start value), 4th, 8th, and 12th week of the test period.

RESULTS

After 12 weeks of administration, the pigmentation scores and melanin index values of the OPC group were significantly reduced from the start value and were lower than the control group (p<0.05). In addition, the OPC group showed a significant increase in water content of the stratum corneum compared to the start value, while that of the control group significantly decreased.

CONCLUSIONS

The red wine OPCs showed the effects of skin whitening and moisturizing, and it is suggested that OPCs may improve the skin condition of healthy women.

A randomized phase 2 trial of pembrolizumab versus pembrolizumab and acalabrutinib in patients with platinum-resistant metastatic urothelial cancer

Background

Inhibition of the programmed cell death protein 1 (PD‐1) pathway has demonstrated clinical benefit in metastatic urothelial cancer (mUC); however, response rates of 15% to 26% highlight the need for more effective therapies. Bruton tyrosine kinase (BTK) inhibition may suppress myeloid‐derived suppressor cells (MDSCs) and improve T‐cell activation.

Methods

The Randomized Phase 2 Trial of Acalabrutinib and Pembrolizumab Immunotherapy Dual Checkpoint Inhibition in Platinum‐Resistant Metastatic Urothelial Carcinoma (RAPID CHECK; also known as ACE‐ST‐005) was a randomized phase 2 trial evaluating the PD‐1 inhibitor pembrolizumab with or without the BTK inhibitor acalabrutinib for patients with platinum‐refractory mUC. The primary objectives were safety and objective response rates (ORRs) according to the Response Evaluation Criteria in Solid Tumors, version 1.1. Secondary endpoints included progression‐free survival (PFS) and overall survival (OS). Immune profiling was performed to analyze circulating monocytic MDSCs and T cells.

Results

Seventy‐five patients were treated with pembrolizumab (n = 35) or pembrolizumab plus acalabrutinib (n = 40). The ORR was 26% with pembrolizumab (9% with a complete response [CR]) and 20% with pembrolizumab plus acalabrutinib (10% with a CR). The grade 3/4 adverse events (AEs) that occurred in ≥15% of the patients were anemia (20%) with pembrolizumab and fatigue (23%), increased alanine aminotransferase (23%), urinary tract infections (18%), and anemia (18%) with pembrolizumab plus acalabrutinib. One patient treated with pembrolizumab plus acalabrutinib had high MDSCs at the baseline, which significantly decreased at week 7. Overall, MDSCs were not correlated with a clinical response, but some subsets of CD8+ T cells did increase during the combination treatment.

Conclusions

Both treatments were generally well tolerated, although serious AE rates were higher with the combination. Acalabrutinib plus pembrolizumab did not improve the ORR, PFS, or OS in comparison with pembrolizumab alone in mUC. Baseline and on‐treatment peripheral monocytic MDSCs were not different in the treatment cohorts. Proliferating CD8+ T‐cell subsets increased during treatment, particularly in the combination cohort. Ongoing studies are correlating these peripheral immunome findings with tissue‐based immune cell infiltration.

In this randomized phase 2 study of metastatic urothelial cancer, a combination of pembrolizumab and a Bruton tyrosine kinase inhibitor (acalabrutinib) does not improve clinical outcomes in comparison with pembrolizumab alone. Comprehensive flow cytometry is used to evaluate circulating immune cells during treatment.

Inhibition of Bruton tyrosine kinase in patients with severe COVID-19

Patients with severe COVID-19 have a hyperinflammatory immune response suggestive of macrophage activation. Bruton tyrosine kinase (BTK) regulates macrophage signaling and activation. Acalabrutinib, a selective BTK inhibitor, was administered off-label to 19 patients hospitalized with severe COVID-19 (11 on supplemental oxygen; 8 on mechanical ventilation), 18 of whom had increasing oxygen requirements at baseline. Over a 10-14 day treatment course, acalabrutinib improved oxygenation in a majority of patients, often within 1-3 days, and had no discernable toxicity. Measures of inflammation – C-reactive protein and IL-6 – normalized quickly in most patients, as did lymphopenia, in correlation with improved oxygenation. At the end of acalabrutinib treatment, 8/11 (72.7%) patients in the supplemental oxygen cohort had been discharged on room air, and 4/8 (50%) patients in the mechanical ventilation cohort had been successfully extubated, with 2/8 (25%) discharged on room air. Ex vivo analysis revealed significantly elevated BTK activity, as evidenced by autophosphorylation, and increased IL-6 production in blood monocytes from patients with severe COVID-19 compared with blood monocytes from healthy volunteers. These results suggest that targeting excessive host inflammation with a BTK inhibitor is a therapeutic strategy in severe COVID-19 and has led to a confirmatory international prospective randomized controlled clinical trial.

Acalabrutinib in treatment-naïve chronic lymphocytic leukemia: Mature results from phase II study demonstrating durable remissions and long-term tolerability

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Background: The next-generation Bruton tyrosine kinase inhibitor acalabrutinib was approved in patients (pts) with treatment-naïve (TN) and relapsed/refractory chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) based on two complementary phase 3 studies, ELEVATE-TN and ASCEND. This report of ACE-CL-001 (NCT02029443), the first phase 2 study of acalabrutinib, provides the longest safety and efficacy follow-up to date in symptomatic TN CLL pts. Methods: Adults with TN CLL/SLL were eligible if they met iwCLL 2008 criteria for treatment, were inappropriate for/declined standard chemotherapy and had ECOG performance status 0–2. Pts received acalabrutinib 100 mg BID or 200 mg QD, later switching to 100 mg BID, until progressive disease (PD) or unacceptable toxicity. Primary endpoint was safety. Events of clinical interest (ECI) were based on combined AE terms for infections, bleeding events, hypertension, and second primary malignancies (SPM) excluding non-melanoma skin, and on a single AE term for atrial fibrillation. Additional endpoints included investigator-assessed overall response rate (ORR), duration of response (DOR), time to response (TTR), and event-free survival (EFS). Results: Ninety-nine pts (n = 62 100 mg BID; n = 37 200 mg QD), were treated [median age: 64 years, 47% Rai stage 3–4 disease, 10% del(17p), 62% unmutated IGHV]. At median follow-up of 53 months (range, 1–59), 85 (86%) pts remain on treatment; most discontinuations were due to AEs (n = 6) or PD (n = 3 [n = 1 Richter transformation]). Most common AEs (any grade) were diarrhea (52%), headache (45%), upper respiratory tract infection (44%), arthralgia (42%), and contusion (42%). All-grade and grade ≥3 ECIs included infection (84%, 15%), bleeding events (66%, 3%), and hypertension (22%, 11%). Atrial fibrillation (all grades) occurred in 5% of pts (incidence: 1% in years 1, 2, 4; 3% in year 3). SPMs excluding non-melanoma skin (all grades) occurred in 11%. Serious AEs were reported in 38% of pts; those in > 2 pts were pneumonia (n = 4) and sepsis (n = 3). ORR was 97% (7% complete response; 90% partial response). Median TTR was 3.7 months (range, 2–22). Response rates were similar across high-risk groups. Median DOR and median EFS were not reached; 48-month DOR rate was 97% (95% CI, 90%–99%), and 48-month EFS rate was 90% (95% CI, 82%–94%). Conclusions: Long-term data from ACE-CL-001 further support the favorable results with acalabrutinib in phase 3 studies and demonstrate durable responses with no new long-term safety issues. Clinical trial information: NCT02029443 .

Acalabrutinib with or without obinutuzumab versus chlorambucil and obinutuzmab for treatment-naive chronic lymphocytic leukaemia (ELEVATE TN): a randomised, controlled, phase 3 trial

BACKGROUND

Acalabrutinib is a selective, covalent Bruton tyrosine-kinase inhibitor with activity in chronic lymphocytic leukaemia. We compare the efficacy of acalabrutinib with or without obinutuzumab against chlorambucil with obinutuzumab in patients with treatment-naive chronic lymphocytic leukaemia.

METHODS

ELEVATE TN is a global, phase 3, multicentre, open-label study in patients with treatment-naive chronic lymphocytic leukaemia done at 142 academic and community hospitals in 18 countries. Eligible patients had untreated chronic lymphocytic leukaemia and were aged 65 years or older, or older than 18 years and younger than 65 years with creatinine clearance of 30-69 mL/min (calculated by use of the Cockcroft-Gault equation) or Cumulative Illness Rating Scale for Geriatrics score greater than 6. Additional criteria included an Eastern Cooperative Oncology Group performance status score of 2 or less and adequate haematologic, hepatic, and renal function. Patients with significant cardiovascular disease were excluded, and concomitant treatment with warfarin or equivalent vitamin K antagonists was prohibited. Patients were randomly assigned (1:1:1) centrally via an interactive voice or web response system to receive acalabrutinib and obinutuzumab, acalabrutinib monotherapy, or obinutuzumab and oral chlorambucil. Treatments were administered in 28-day cycles. To reduce infusion-related reactions, acalabrutinib was administered for one cycle before obinutuzumab administration. Oral acalabrutinib was administered (100 mg) twice a day until progressive disease or unacceptable toxic effects occurred. In the acalabrutinib-obinutuzumab group, intravenous obinutuzumab was given on days 1 (100 mg), 2 (900 mg), 8 (1000 mg), and 15 (1000 mg) of cycle 2 and on day 1 (1000 mg) of cycles 3-7. In the obinutuzumab-chlorambucil group, intravenous obinutuzumab was given on days 1 (100 mg), 2 (900 mg), 8 (1000 mg), and 15 (1000 mg) of cycle 1 and on day 1 (1000 mg) of cycles 2-6. Oral chlorambucil was given (0·5 mg/kg) on days 1 and 15 of each cycle, for six cycles. The primary endpoint was progression-free survival between the two combination-therapy groups, assessed by independent review committee. Crossover to acalabrutinib was allowed in patients who progressed on obinutuzumab-chlorambucil. Safety was assessed in all patients who received at least one dose of treatment. Enrolment for this trial is complete, and the study is registered at ClinicalTrials.gov, NCT02475681.

FINDINGS

Between Sept 14, 2015, and Feb 8, 2017, we recruited 675 patients for assessment. 140 patients did not meet eligibility criteria, and 535 patients were randomly assigned to treatment. 179 patients were assigned to receive acalabrutinib-obinutuzumab, 179 patients were assigned to receive acalabrutinib monotherapy, and 177 patients were assigned to receive obinutuzumab-chlorambucil. At median follow-up of 28·3 months (IQR 25·6-33·1), median progression-free survival was longer with acalabrutinib-obinutuzumab and acalabrutinib monotherapy, compared with obinutuzumab-chlorambucil (median not reached with acalabrutinib and obinutuzumab vs 22·6 months with obinutuzumab, hazard ratio [HR] 0·1; 95% CI 0·06-0·17, p<0·0001; and not reached with acalabrutinib monotherapy vs 22·6 months with obinutuzumab, 0·20; 0·13-0·3, p<0·0001). Estimated progression-free survival at 24 months was 93% with acalabrutinib-obinutuzumab (95% CI 87-96%), 87% with acalabrutinib monotherapy (81-92%), and 47% with obinutuzumab-chlorambucil (39-55%). The most common grade 3 or higher adverse event across groups was neutropenia (53 [30%] of 178 patients in the acalabrutinib-obinutuzumab group, 17 [9%] of 179 patients in the acalabrutinib group, and 70 [41%] of 169 patients in the obinutuzumab-chlorambucil group). All-grade infusion reactions were less frequent with acalabrutinib-obinutuzumab (24 [13%] of 178 patients) than obinutuzumab-chlorambucil (67 [40%] of 169 patients). Grade 3 or higher infections occurred in 37 (21%) patients given acalabrutinib-obinutuzumab, 25 (14%) patients given acalabrutinib monotherapy, and 14 (8%) patients given obinutuzumab-chlorambucil. Deaths occurred in eight (4%) patients given acalabrutinib-obinutuzumab, 12 (7%) patients given acalabrutinib, and 15 (9%) patients given obinutuzumab-chlorambucil.

INTERPRETATION

Acalabrutinib with or without obinutuzumab significantly improved progression-free survival over obinutuzumab-chlorambucil chemoimmunotherapy, providing a chemotherapy-free treatment option with an acceptable side-effect profile that was consistent with previous studies. These data support the use of acalabrutinib in combination with obinutuzumab or alone as a new treatment option for patients with treatment-naive symptomatic chronic lymphocytic leukaemia.

FUNDING

Acerta Pharma, a member of the AstraZeneca Group, and R35 CA198183 (to JCB).

Pharmacodynamic Analysis of BTK Inhibition in Patients with Chronic Lymphocytic Leukemia Treated with Acalabrutinib

PURPOSE

To determine the pharmacodynamic relationship between target occupancy of Bruton tyrosine kinase (BTK) and inhibition of downstream signaling.

PATIENTS AND METHODS

Patients with chronic lymphocytic leukemia (CLL) enrolled in a phase II clinical trial (NCT02337829) with the covalent, selective BTK inhibitor acalabrutinib donated blood samples for pharmacodynamic analyses. Study design included randomization to acalabrutinib 100 mg twice daily or 200 mg once daily and dose interruptions on day 4 and 5 of the first week. BTK occupancy and readouts of intracellular signaling were assessed sequentially between 4 and 48 hours from last dose.

RESULTS

Four hours from last dose, BTK occupancy exceeded 96% and at trough, was higher with twice daily, median 95.3%, than with once daily dosing, median 87.6% (P < 0.0001). By 48 hours from last dose, median free BTK increased to 25.6%. Due to covalent binding of acalabrutinib, free BTK is generated by de novo synthesis. The estimated rate of BTK synthesis varied widely between patients ranging from 3.6% to 31.4% per day. Acalabrutinib reduced phosphorylation of BTK and inhibited downstream B-cell receptor (BCR) and NFκB signaling. During dosing interruptions up to 48 hours, expression of BCR target genes rebounded, while phosphorylation of signaling molecules remained repressed. In vitro cross-linking of IgM on CLL cells obtained 36 to 48 hours from last dose upregulated CD69, with high correlation between cellular free BTK and response (R = 0.7, P ≤ 0.0001).

CONCLUSIONS

Higher BTK occupancy was achieved with twice daily over once daily dosing, resulting in deeper and more sustained inhibition of BCR signaling.

Acalabrutinib monotherapy in patients with Waldenström macroglobulinemia: a single-arm, multicentre, phase 2 study

BACKGROUND

Chemoimmunotherapy is typically the standard of care for patients with Waldenström macroglobulinemia; however, infectious and hematologic toxic effects are problematic. Acalabrutinib is a selective, potent Bruton tyrosine-kinase inhibitor. The aim of this trial was to evaluate the activity and safety of acalabrutinib in patients with Waldenström macroglobulinemia.

METHODS

This single-arm, multicentre, phase 2 trial was done in 19 European academic centres in France, Italy, Greece, the Netherlands, and the UK, and eight academic centres in the USA. Eligible patients were 18 years or older and had treatment naive (declined or not eligible for chemoimmunotherapy) or relapsed or refractory (at least one previous therapy) Waldenström macroglobulinemia that required treatment, an Eastern Cooperative Oncology Group performance status of 2 or less, and received no previous Bruton tyrosine-kinase inhibitor therapy. Patients received 100 mg oral acalabrutinib twice per day in 28-day cycles until disease progression or unacceptable toxicity. The primary endpoint was investigator-assessed overall response (at least a minor response) according to the 6th International Workshop for Waldenström Macroglobulinemia (IWWM) and the modified 3rd IWWM workshop criteria. The primary outcome and safety were assessed in all patients who received at least one dose of treatment. This study is registered with ClinicalTrials.gov, number NCT02180724, and is ongoing, but no longer enrolling.

FINDINGS

Between Sept 8, 2014, and Dec 24, 2015, 122 patients were assessed for eligibility, of which 106 (87%) patients were given acalabrutinib (14 were treatment naive and 92 had relapsed or refractory disease). With a median follow-up of 27·4 months (IQR 26·0-29·7), 13 (93% [95% CI 66-100]) of 14 treatment naive patients achieved an overall response and 86 (93% [86-98]) of 92 relapsed or refractory patients per both the modified 3rd and 6th IWWM criteria. Seven (50%) of 14 treatment naive patients and 23 (25%) of 92 relapsed or refractory patients discontinued treatment on study. Grade 3-4 adverse events occurring in more than 5% of patients were neutropenia (17 [16%] of 106 patients) and pneumonia (7 [7%]). Grade 3-4 atrial fibrillation occurred in one (1%) patient and grade 3-4 bleeding occurred in three (3%) patients. The most common serious adverse events were lower respiratory tract infection (n=7 [7%]), pneumonia (n=7 [7%]), pyrexia (n=4 [4%]), cellulitis (n=3 [3%]), fall (n=3 [3%]), and sepsis (n=3 [3%]). Pneumonia (n=5 [5%]) and lower respiratory tract infection (n=4 [4%]) were considered treatment related. One treatment-related death was reported (intracranial hematoma).

INTERPRETATION

This study provides evidence that acalabrutinib is active as single-agent therapy with a manageable safety profile in patients with treatment-naive, or relapse or refractory Waldenström macroglobulinemia. Further studies are needed to establish its efficacy against current standard treatments and to investigate whether outcomes can be improved with combination therapies.

FUNDING

Acerta Pharma.

Acalabrutinib plus Obinutuzumab in Treatment-Naïve and Relapsed/Refractory Chronic Lymphocytic Leukemia

Acalabrutinib is a selective irreversible Bruton tyrosine kinase (BTK) inhibitor that does not affect IL2-associated tyrosine kinase or antibody-dependent cellular cytotoxicity, making it an attractive candidate for combination therapy with anti-CD20 antibodies. We investigated acalabrutinib plus obinutuzumab in a phase Ib/II study (NCT02296918) of patients with treatment-naïve or relapsed/refractory chronic lymphocytic leukemia (CLL). Nineteen treatment-naïve and 26 relapsed/refractory patients were treated with acalabrutinib (100 mg twice daily) until progression and obinutuzumab (cycle 1: 100 mg day 1, 900 mg day 2, 1000 mg days 8 and 15; cycles 2-6: 1,000 mg day 1). Grade 3/4 adverse events occurred in 71% of patients. Overall response rates were 95% (treatment-naïve) and 92% (relapsed/refractory). Thirty-two percent of treatment-naïve and 8% of relapsed/refractory patients achieved complete remission. At 36 months, 94% (treatment-naïve) and 88% (relapsed/refractory) were progression free. Acalabrutinib plus obinutuzumab was well tolerated, producing high and durable responses in treatment-naïve and relapsed/refractory CLL. SIGNIFICANCE: Rituximab plus the less selective BTK inhibitor ibrutinib has not shown benefit in CLL; however, the selective BTK inhibitor acalabrutinib plus the antibody-dependent cellular cytotoxicity-enhanced antibody obinutuzumab yielded durable responses that deepened over time in treatment-naïve and relapsed/refractory CLL, supporting the evaluation of this approach in larger, comparative studies in CLL.This article is highlighted in the In This Issue feature, p. 327.

Acalabrutinib with obinutuzumab (Ob) in treatment-naive (TN) and relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL): Three-year follow-up

7500

Background: Acalabrutinib is a highly selective, potent, covalent Bruton tyrosine kinase inhibitor. This Phase 1b/2 trial evaluated acalabrutinib with the CD20 antibody Ob in TN and R/R CLL. Methods: Patient (pts) with TN and R/R (≥1 prior therapy) CLL were eligible. In 28-day cycles, acalabrutinib was given at 100 mg BID or 200 mg QD PO (n=15; all switched to 100 mg BID) until progressive disease (PD); Ob was given in standard fashion for 6 cycles starting with Cycle 2. The primary endpoints were overall response rate (ORR) and safety. Minimal residual disease (MRD) was assessed using flow cytometry (sensitivity 10-4). Results: 19 TN and 26 R/R pts were treated; median age of all pts was 61 y (range 42-76). Pt characteristics, disposition, efficacy and MRD are in the Table. Common adverse events (AEs; any grade) were upper respiratory tract infection (71%), increased weight (71%), maculopapular rash (67%), cough (64%), diarrhea (62%), headache (56%), nausea (53%), arthralgia (51%) and dizziness (47%). Common Gr 3/4 AEs were decreased neutrophil count (24%), syncope (11%), decreased platelet count, increased weight and cellulitis (9% each). There were 2 (4%) Gr 3 bleeding events (hematuria, muscle hemorrhage) and 1 (2%) Gr 3 atrial fibrillation event. Conclusions: Acalabrutinib plus Ob was well tolerated and yielded high response rates that were durable and deepened over time in TN and R/R CLL patients. Clinical trial information: NCT02296918. [Table: see text]

Phase 2 study of acalabrutinib in ibrutinib (IBR)-intolerant patients (pts) with relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL)

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Background: In CLL pts treated with the Bruton tyrosine kinase (BTK) inhibitor IBR, the most common reason for discontinuation was adverse events (AEs; 50%-63%; Mato et al, 2018). This Phase 2 trial evaluated acalabrutinib, a highly selective, potent, covalent BTK inhibitor, in IBR-intolerant pts with R/R CLL. Methods: Pts with R/R CLL (≥1 prior therapy) who discontinued IBR due to Gr 3/4 AEs or persistent/recurrent Gr 2 AEs and had progressive disease (PD) after IBR discontinuation were eligible. Acalabrutinib was given at 100 mg BID PO in 28-d cycles until PD or unacceptable toxicity. The primary endpoint was overall response rate (ORR). Results: 60 pts were treated (median age 70 y [range 43-88]). Pt characteristics included bulky disease ≥5 cm (33%), Rai stage III/IV (47%), del17p (28%), del11q (23%) and unmutated IGHV (79%). 52/55 (95%) pts with available baseline samples were wild type for BTK and PLCG2. Median number of prior therapies was 2 (range 1-10). Median duration of prior IBR therapy was 6 mo (range <1-55); common AEs that led to IBR discontinuation were atrial fibrillation/flutter (25%), diarrhea (12%), arthralgia (10%) and rash (12%). At a median follow-up of 19 mo (range 1-31), 67% of pts remain on acalabrutinib; discontinuations were mostly due to PD (13%) and AEs (10%; pneumonia [n=2], diarrhea, headache, ascites, arthralgia, subdural hematoma [all n=1]). Efficacy outcomes are in the Table. Common AEs (any grade) were diarrhea (48%), headache (40%), contusion (35%) and dizziness (32%). Serious AEs (≥2 pts) were pneumonia (10%), anemia (3%) and syncope (3%). Atrial fibrillation occurred in 3 pts (5%; all Gr 1/2) and major hemorrhage in 2 (3%; Gr 3 hematuria and Gr 2 subdural hematoma). Gr 5 AEs were pneumonia (n=2), bronchopulmonary aspergillosis (n=1) and ventricular fibrillation (n=1), all considered not related to treatment. Conclusions: Acalabrutinib is tolerable and effective in IBR-intolerant pts, providing a viable strategy for continuing BTK inhibitor therapy. Clinical trial information: NCT02717611. [Table: see text]

Acalabrutinib in relapsed or refractory mantle cell lymphoma (ACE-LY-004): a single-arm, multicentre, phase 2 trial

BACKGROUND

Bruton tyrosine kinase is a clinically validated target in mantle cell lymphoma. Acalabrutinib (ACP-196) is a highly selective, potent Bruton tyrosine kinase inhibitor developed to minimise off-target activity.

METHODS

In this open-label, phase 2 study, oral acalabrutinib (100 mg twice per day) was given to patients with relapsed or refractory mantle cell lymphoma, until disease progression or unacceptable toxicity. The primary endpoint was overall response assessed according to the Lugano classification, and safety analyses were done in all participants. This trial is registered with ClinicalTrials.gov, number NCT02213926.

FINDINGS

From March 12, 2015, to Jan 5, 2016, 124 patients with relapsed or refractory mantle cell lymphoma were enrolled and all patients received treatment; median age 68 years. Patients received a median of two (IQR 1-2) previous therapies. At a median follow-up of 15·2 months, 100 (81%) patients achieved an overall response and 49 (40%) patients achieved a complete response. The Kaplan-Meier estimated medians for duration of response, progression-free survival, and overall survival were not reached; the 12-month rates were 72% (95% CI 62-80), 67% (58-75), and 87% (79-92%), respectively. The most common adverse events were primarily grade 1 or 2 and were headache (47 [38%]), diarrhoea (38 [31%]), fatigue (34 [27%]), and myalgia (26 [21%]). The most common grade 3 or worse adverse events were neutropenia (13 [10%]), anaemia (11 [9%]), and pneumonia (six [5%]). There were no cases of atrial fibrillation and one case of grade 3 or worse haemorrhage. The median duration of treatment was 13·8 months. Treatment was discontinued in 54 (44%) patients, primarily due to progressive disease (39 [31%]) and adverse events (seven [6%]).

INTERPRETATION

Acalabrutinib treatment provided a high rate of durable responses and a favourable safety profile in patients with relapsed or refractory mantle cell lymphoma. These findings suggest an important role for acalabrutinib in the treatment of this disease population.

FUNDING

Acerta Pharma, a member of the AstraZeneca Group.

Acalabrutinib (ACP-196): A Covalent Bruton Tyrosine Kinase Inhibitor with a Differentiated Selectivity and In Vivo Potency Profile

Several small-molecule Bruton tyrosine kinase (BTK) inhibitors are in development for B cell malignancies and autoimmune disorders, each characterized by distinct potency and selectivity patterns. Herein we describe the pharmacologic characterization of BTK inhibitor acalabrutinib [compound 1, ACP-196 (4-[8-amino-3-[(2S)-1-but-2-ynoylpyrrolidin-2-yl]imidazo[1,5-a]pyrazin-1-yl]-N-(2-pyridyl)benzamide)]. Acalabrutinib possesses a reactive butynamide group that binds covalently to Cys481 in BTK. Relative to the other BTK inhibitors described here, the reduced intrinsic reactivity of acalabrutinib helps to limit inhibition of off-target kinases having cysteine-mediated covalent binding potential. Acalabrutinib demonstrated higher biochemical and cellular selectivity than ibrutinib and spebrutinib (compounds 2 and 3, respectively). Importantly, off-target kinases, such as epidermal growth factor receptor (EGFR) and interleukin 2-inducible T cell kinase (ITK), were not inhibited. Determination of the inhibitory potential of anti-immunoglobulin M-induced CD69 expression in human peripheral blood mononuclear cells and whole blood demonstrated that acalabrutinib is a potent functional BTK inhibitor. In vivo evaluation in mice revealed that acalabrutinib is more potent than ibrutinib and spebrutinib. Preclinical and clinical studies showed that the level and duration of BTK occupancy correlates with in vivo efficacy. Evaluation of the pharmacokinetic properties of acalabrutinib in healthy adult volunteers demonstrated rapid absorption and fast elimination. In these healthy individuals, a single oral dose of 100 mg showed approximately 99% median target coverage at 3 and 12 hours and around 90% at 24 hours in peripheral B cells. In conclusion, acalabrutinib is a BTK inhibitor with key pharmacologic differentiators versus ibrutinib and spebrutinib and is currently being evaluated in clinical trials.

Combined BTK and PI3Kδ Inhibition with Acalabrutinib and ACP-319 Improves Survival and Tumor Control in CLL Mouse Model

Purpose: Targeting the B-cell receptor (BCR) pathway with inhibitors of Bruton tyrosine kinase (BTK) and PI3Kδ is highly effective for the treatment of chronic lymphocytic leukemia (CLL). However, deep remissions are uncommon, and drug resistance with single-agent therapy can occur. In vitro studies support the effectiveness of combing PI3Kδ and BTK inhibitors.Experimental Design: As CLL proliferation and survival depends on the microenvironment, we used murine models to assess the efficacy of the BTK inhibitor acalabrutinib combined with the PI3Kδ inhibitor ACP-319 in vivo We compared single-agent with combination therapy in TCL1-192 cell-injected mice, a model of aggressive CLL.Results: We found significantly larger reductions in tumor burden in the peripheral blood and spleen of combination-treated mice. Although single-agent therapy improved survival compared with control mice by a few days, combination therapy extended survival by over 2 weeks compared with either single agent. The combination reduced tumor proliferation, NF-κB signaling, and expression of BCL-xL and MCL-1 more potently than single-agent therapy.Conclusions: The combination of acalabrutinib and ACP-319 was superior to single-agent treatment in a murine CLL model, warranting further investigation of this combination in clinical studies. Clin Cancer Res; 23(19); 5814-23. ©2017 AACR.

The Bruton Tyrosine Kinase (BTK) Inhibitor Acalabrutinib Demonstrates Potent On-Target Effects and Efficacy in Two Mouse Models of Chronic Lymphocytic Leukemia

Purpose: Acalabrutinib (ACP-196) is a novel, potent, and highly selective Bruton tyrosine kinase (BTK) inhibitor, which binds covalently to Cys481 in the ATP-binding pocket of BTK. We sought to evaluate the antitumor effects of acalabrutinib treatment in two established mouse models of chronic lymphocytic leukemia (CLL).Experimental Design: Two distinct mouse models were used, the TCL1 adoptive transfer model where leukemic cells from Eμ-TCL1 transgenic mice are transplanted into C57BL/6 mice, and the human NSG primary CLL xenograft model. Mice received either vehicle or acalabrutinib formulated into the drinking water.Results: Utilizing biochemical assays, we demonstrate that acalabrutinib is a highly selective BTK inhibitor as compared with ibrutinib. In the human CLL NSG xenograft model, treatment with acalabrutinib demonstrated on-target effects, including decreased phosphorylation of PLCγ2, ERK, and significant inhibition of CLL cell proliferation. Furthermore, tumor burden in the spleen of the mice treated with acalabrutinib was significantly decreased compared with vehicle-treated mice. Similarly, in the TCL1 adoptive transfer model, decreased phosphorylation of BTK, PLCγ2, and S6 was observed. Most notably, treatment with acalabrutinib resulted in a significant increase in survival compared with mice receiving vehicle.Conclusions: Treatment with acalabrutinib potently inhibits BTK in vivo, leading to on-target decreases in the activation of key signaling molecules (including BTK, PLCγ2, S6, and ERK). In two complementary mouse models of CLL, acalabrutinib significantly reduced tumor burden and increased survival compared with vehicle treatment. Overall, acalabrutinib showed increased BTK selectivity compared with ibrutinib while demonstrating significant antitumor efficacy in vivo on par with ibrutinib. Clin Cancer Res; 23(11); 2831-41. ©2016 AACR.

Galectin-7 in the stratum corneum: a biomarker of the skin barrier function

OBJECTIVE

Skin barrier disruption often occurs in diseased and damaged skin conditions such as atopic dermatitis (AD). We focused the galectin-7 protein (Gal-7) as a biomarker of skin condition and assessed whether the content of Gal-7 in stratum corneum (scGal-7) could be used as an indicator of skin barrier disruption and as an index of local skin symptoms in AD patients.

METHODS

Alteration of Gal-7 expression levels in keratinocyte and scGal-7 contents after barrier disruption by sodium dodecyl sulphate were evaluated in vitro and in vivo, respectively. Correlation between scGal-7 content and transepidermal water loss (TEWL) was examined in 126 healthy subjects. We performed single measurements of scGal-7 contents in 34 AD patients and serial measurements of 15 inpatients among them. SC samples were collected by the tape-stripping method, and scGal-7 content was determined using enzyme-linked immunosorbent assay.

RESULTS

Gal-7 expression in keratinocytes increased after barrier disruption. The scGal-7 content reflected the disruption of the skin barrier. The scGal-7 contents and TEWL values correlated in healthy subjects. The scGal-7 level was higher in AD patients than in healthy subjects. The scGal-7 contents in the cheek and neck of AD patients significantly correlated with the total and local skin lesion severity scores. Serial measurements in the inpatients showed that the scGal-7 contents in the cheek and neck decreased in tandem with local severity scores in response to treatment.

CONCLUSION

Measurement of scGal-7 content in tape-stripped samples was useful for the evaluation of the skin barrier function in dry skin conditions such as AD.

Acalabrutinib (ACP-196) in Relapsed Chronic Lymphocytic Leukemia

BACKGROUND

Irreversible inhibition of Bruton's tyrosine kinase (BTK) by ibrutinib represents an important therapeutic advance for the treatment of chronic lymphocytic leukemia (CLL). However, ibrutinib also irreversibly inhibits alternative kinase targets, which potentially compromises its therapeutic index. Acalabrutinib (ACP-196) is a more selective, irreversible BTK inhibitor that is specifically designed to improve on the safety and efficacy of first-generation BTK inhibitors.

METHODS

In this uncontrolled, phase 1-2, multicenter study, we administered oral acalabrutinib to 61 patients who had relapsed CLL to assess the safety, efficacy, pharmacokinetics, and pharmacodynamics of acalabrutinib. Patients were treated with acalabrutinib at a dose of 100 to 400 mg once daily in the dose-escalation (phase 1) portion of the study and 100 mg twice daily in the expansion (phase 2) portion.

RESULTS

The median age of the patients was 62 years, and patients had received a median of three previous therapies for CLL; 31% had chromosome 17p13.1 deletion, and 75% had unmutated immunoglobulin heavy-chain variable genes. No dose-limiting toxic effects occurred during the dose-escalation portion of the study. The most common adverse events observed were headache (in 43% of the patients), diarrhea (in 39%), and increased weight (in 26%). Most adverse events were of grade 1 or 2. At a median follow-up of 14.3 months, the overall response rate was 95%, including 85% with a partial response and 10% with a partial response with lymphocytosis; the remaining 5% of patients had stable disease. Among patients with chromosome 17p13.1 deletion, the overall response rate was 100%. No cases of Richter's transformation (CLL that has evolved into large-cell lymphoma) and only one case of CLL progression have occurred.

CONCLUSIONS

In this study, the selective BTK inhibitor acalabrutinib had promising safety and efficacy profiles in patients with relapsed CLL, including those with chromosome 17p13.1 deletion. (Funded by the Acerta Pharma and others; ClinicalTrials.gov number, NCT02029443.).