2022 EHA: PRELIMINARY ANALYSIS OF THE PHASE II STUDY USING TOLINAPANT (ASTX660) MONOTHERAPY IN 98 PERIPHERAL T-CELL LYMPHOMA AND 51 CUTANEOUS T-CELL LYMPHOMA SUBJECTS WITH RELAPSED REFRACTORY DISEASE

View Presentation

PRELIMINARY ANALYSIS OF THE PHASE II STUDY USING TOLINAPANT (ASTX660) MONOTHERAPY IN 98 PERIPHERAL T-CELL LYMPHOMA AND 51 CUTANEOUS T-CELL LYMPHOMA SUBJECTS WITH RELAPSED REFRACTORY DISEASE

Abstract:

Background: There are limited treatment options for patients with Peripheral T-cell lymphoma (PTCL) and Cutaneous T-cell lymphoma (CTCL), especially when front line therapy has failed. Tolinapant (ASTX660) is a novel oral nonpeptidomimetic, small-molecule antagonist of cellular/X-linked inhibitors of apoptosis proteins (cIAP1/2 and XIAP), which also induces necroptosis in T-cell lymphoma models (Ferrari et al., Blood Advances, 2021). Tolinapant is being evaluated in a first-in-human ongoing Phase I/II study in subjects with advanced solid tumors and lymphoma (ClinicalTrials.gov NCT02503423). Phase I results were previously reported (Mita et al. Clin Cancer Res, 2020) and the recommended phase 2 dosing (RP2D) was established. Initial results for Phase II were previously reported at EHA 2019 (Mehta et al., EHA 2019, # PS1073).

Aims: Here we report the preliminary efficacy and safety analysis for the Phase 2 PTCL and CTCL cohorts.

Methods: Methods: This is a single-arm open-label Phase II study. To be eligible, subjects must have evidence of documented progressive disease and received at least two prior systemic therapies. Subjects received treatment with tolinapant at the RP2D 180 mg/day on Days 1 to 7, and 15 to 22 in a 28-day cycle. The primary endpoint is best overall response rate (ORR) as assessed by the investigator according to either the Lugano criteria (PTCL) or Global Assessment (CTCL). Adverse events (AEs) are assessed per CTCAE v4.03. The efficacy data set is based on subjects who had tumor evaluation at baseline and at least 1 post-treatment tumor evaluation visit, unless they died or stopped treatment earlier due to clinical progression or toxicity. The safety data set is based on all subjects that received at least one dose of tolinapant.

Results: Results: As of the data cut of January 5, 2022, there were 98 subjects with PTCL and 51 subjects with CTCL that received drug and 98 and 50 subjects that were evaluable respectively. The study is currently closed to enrollment with a minimum of 6 months follow-up on all subjects at the time of the data cut. Subject characteristics: median (range) age PTCL 62.5 (27, 82) and CTCL 62 (24,87), median number of previous therapies PTCL 3 (0-8) and CTCL 6 (1-10). Among all subjects, the most common related AEs of any grade (≥ 15%) were: lipase elevation (35%), amylase elevation (25%), rash (combined listings) (24%), ALT elevation (15%), and AST elevation (15%). Related AEs ≥ Grade 3 (≥ 5%) were: lipase elevation (15%), rash (combined listings) (9%), and amylase elevation (7%). Pancreatitis was identified in 2 subjects (1%) (both Grade 4). There were no related ≥ Grade 3 AEs for diarrhea, nausea or vomiting; for related Grade 2 AEs there was a 5% incidence of diarrhea and 1% incidence of nausea/vomiting.

The ORR for PTCL is 22%, including 9 complete responses (CRs) and 12 partial responses (PRs). The ORR in CTCL is 26% including 2 CRs and 11 PRs. The median durability of response for PTCL is 133 (Q1-Q3; 69 – 280) days and for CTCL is 148 (Q1-Q3; 103 – 294) days. Pharmacodynamic and correlative analysis is ongoing with preliminary analysis suggesting an immunomodulatory antitumoral effect of tolinapant (Ferrari et al., Blood Advances, 2021).

Summary/Conclusion: In this Phase II study, the novel oral agent tolinapant has shown meaningful clinical activity against PTCL and CTCL with a manageable safety profile. These results support the continued development of tolinapant for the treatment of R/R PTCL and CTCL. A drug combination study using tolinapant in R/R PTCL is being developed.

2022 EHA: PHARMACOKINETIC EXPOSURE EQUIVALENCE AND PRELIMINARY EFFICACY AND SAFETY FROM A RANDOMIZED CROSSOVER PHASE 3 STUDY OF AN ORAL HYPOMETHYLATING AGENT, ASTX727 (DEC-C), COMPARED TO IV DECITABINE IN AML PATIENTS

View poster: 

PHARMACOKINETIC EXPOSURE EQUIVALENCE AND PRELIMINARY EFFICACY AND SAFETY FROM A RANDOMIZED CROSSOVER PHASE 3 STUDY OF AN ORAL HYPOMETHYLATING AGENT, ASTX727 (DEC-C), COMPARED TO IV DECITABINE IN AML PATIENTS

Abstract:

Background: Parenterally administered hypomethylating agents (HMAs), decitabine (DEC) and azacitidine (AZA), are approved in Europe for adult patients with acute myeloid leukemia (AML) who are not candidates for standard induction chemotherapy as single agent or in combination with venetoclax. ASTX727 (DEC-C) is a fixed dose combination (FDC) tablet of 35 mg DEC and 100 mg cedazuridine, a novel cytidine deaminase inhibitor (CDAi). In clinical trials with myelodysplastic syndromes (MDS)/chronic myelomonocytic leukemia (CMML) patients, DEC-C provides DEC exposures that are equivalent to IV DEC at the approved dose of 20 mg/m2 daily×5 and is approved as INQOVI® in the US, Canada, and Australia.

Aims: To demonstrate DEC exposure bioequivalence of oral DEC-C and IV-DEC and generate clinical data using DEC-C in AML patients.

Methods: The ASCERTAIN study was a randomized cross over design. Patients were randomized 1:1 to either Sequence A: DEC-C (35 mg DEC/100 mg cedazuridine) in Cycle 1 followed by IV-DEC at 20 mg/m2 in Cycle 2, or Sequence B: receiving IV-DEC in Cycle 1 followed by DEC-C on Cycle 2 to compare PK [primary endpoint Area Under the Curve (AUC) equivalence over 5 days of dosing]. All patients received DEC-C from Cycle 3 onwards until treatment discontinuation to assess safety and clinical efficacy. Patients were eligible as per the EMA-approved decitabine label (newly diagnosed AML who are not candidates for standard induction chemotherapy). Clinical responses were assessed according to modified International Working Group (IWG) 2003 response criteria.

Results: 89 patients were randomized, of whom 87 were treated. The median age of patients was 78.0 years (range, 61 to 92) with 31 (35.6%) males and 56 (64.4%) females. Cytogenetic risk classification was poor-risk in 33 (37.9%) and intermediate-risk in 45 (51.7%) patients. For the primary endpoint, preliminary PK data was available from 69 patients who successfully completed PK assessments for both IV DEC and DEC-C cycles, and the DEC AUC0-24 (h*ng/mL) 5-Day geometric mean estimate was 904 for DEC-C and 907 for IV-DEC resulting in an oral/IV geometric LSM AUC ratio of 99.64% (90% CI of 91.23-108.8%). Safety findings were consistent with those anticipated for IV-DEC (related Grade ≥ 3 AEs in more than 10% were thrombocytopenia, anemia, febrile neutropenia, neutropenia, and pneumonia). As of the data cutoff date (10 SEP 2021), median follow up was 7.95 months (IQR 6.11-11.86). Of the 77 patients who had ≥6 months of follow up or discontinued treatment, the best response was complete response (CR) in 17 (22.1%, 95% CI: 13.4, 33.0%). In addition, 4 patients (5.2%) had CR with incomplete blood cell count recovery (CRi), with 1 patient (1.3%) who had CR with incomplete platelet recovery (CRp), resulting in composite response rate [CR + CRp] of 23.4% [18/77 patients, 95% CI: 14.5, 34.4%]. These results obtained with DEC-C are consistent with those observed for IV DEC. Based on preliminary and limited study follow-up with ~46% censored observations, the median survival was approximately 7.9 months (95% CI: 5.9, 13.0).

Summary/Conclusion: This randomized phase 3 study in AML patients not candidates for standard induction chemotherapy demonstrates that the oral FDC of DEC-C (35mg/100 mg) resulted in an equivalent DEC AUC exposure to IV-DEC at 20 mg/m2 over 5 days. In addition, safety findings and preliminary clinical activity is also consistent with published data from IV-DEC, suggesting that DEC-C has the potential to be an oral alternative to the standard IV decitabine Daily×5 regimen.

2022 EHA: GUADECITABINE (SGI-110) VS. TREATMENT CHOICE (TC) IN RELAPSED/REFRACTORY(R/R) MYELODYSPLASTIC SYNDROME (MDS), RESULTS OF A GLOBAL, RANDOMIZED, PHASE 3 STUDY

View Poster:

GUADECITABINE (SGI-110) VS. TREATMENT CHOICE (TC) IN RELAPSED/REFRACTORY(R/R) MYELODYSPLASTIC SYNDROME (MDS), RESULTS OF A GLOBAL, RANDOMIZED, PHASE 3 STUDY

Background: Guadecitabine (G) is a next-generation hypomethylating agent (HMA), administered as a small-volume subcutaneous (SC) injection, designed with the potential to overcome pharmacokinetic resistance to first-generation HMAs (decitabine and azacitidine). Preliminary guadecitabine phase 2 data in r/r MDS showed an overall survival of almost 12 months (Garcia-Manero,G, et al; Lancet Haematol http://dx.doi.org/10.1016/S2352-3026 [19]30029-8) leading to the ASTRAL-3 study.

Aims: Compare overall survival of guadecitabine to that of TC consisting of low-dose cytarabine (LDAC), intensive chemotherapy (IC), or best supportive care (BSC). Secondary objectives included multiple standard assessments of response and safety.

Methods: Subjects with r/r MDS or Chronic Myelomonocytic Leukemia (CMML) who had progressed or failed to respond after 6 full cycles of standard HMA therapy were randomized 2:1 between guadecitabine (60 mg/m2) SC Days 1-5 every 28 days vs. a pre-selected TC (BSC, IC, or LDAC). Stratification was by disease, disease burden
(>10% bone marrow blasts or not, geography, and pre-selected TC option). Primary endpoint was overall survival
(OS) and the study was designed with ~90% power to detect a hazard ratio of 0.68 (approximately 2.8 month
difference in median survival).

Results: 417 MDS/CMML subjects were randomized to G or TC (G:277, TC: 140). Demographics and disease status were reasonably balanced across the groups (see Table 1 below) as was percentage of commonly associated genetic
mutations (TET2, DNMT3A, SF3Baa, RUNX1, and TP53). Median guadecitabine exposure was 4 cycles and 3 cycles
for TC. Neither overall survival (G: median 9.1 months, TC: median 8.3 months, p=0.61, HR:0.94 with 95% CI:
[0.74-1.19]) nor leukemia-free survival (LFS) (G: median 5.7 months, TC: median 5.9 months; p=0.38) demonstrated
a significant difference between the two groups and subgroup analyses did not suggest a difference between
guadecitabine and any of the different TC options or different genetic mutations. Transfusion dependence for 8 weeks
was similar with 32.1% and 22.4% of the G group and 37.9% and 20.0% of the TC group being platelet transfusion
or red blood cell transfusion independent, respectively. Safety was consistent with known profiles of the respective
agents with the G group having a slightly higher overall incidence of adverse events (AE) (99.3% vs 92.6% for TC)
and grade 3 or higher AE (92.2% vs 70.5% for TC). The AEs with the highest incidence in subjects who received
guadecitabine were febrile neutropenia (38.5 vs 18.9% for TC), pneumonia (34.4% vs 18.9% for TC), neutropenia
(34.1% vs 15.6% for TC), and thrombocytopenia (32.2% vs 21.3% for TC).

Summary/Conclusion: This large, global, randomized phase 3 study did not demonstrate superiority of guadecitabine
over Standard TC in MDS/CMML patients who were refractory or relapsed following full course of prior HMA
treatment.

2022 EHA: COMBINING THE IAP ANTAGONIST, TOLINAPANT, WITH A DNA HYPOMETHYLATING AGENT ENHANCES ANTI-TUMOUR MECHANISMS IN PRECLINICAL MODELS OF T-CELL LYMPHOMA

View Poster
COMBINING THE IAP ANTAGONIST, TOLINAPANT, WITH A DNA HYPOMETHYLATING AGENT ENHANCES ANTI-TUMOUR MECHANISMS IN PRECLINICAL MODELS OF T-CELL LYMPHOMA

Abstract:
Background: Tolinapant is a potent, non-peptidomimetic antagonist of cIAP1, cIAP2 and XIAP. In a Phase 2 trial (NCT02503423), tolinapant has shown activity against highly pre-treated peripheral and cutaneous T-cell lymphoma (Samaniego et al., Hematological Oncology, 2019). Hypomethylating agents (HMAs) have also shown clinical responses in some subsets of PTCL (Lemonnier et al., Blood, 2019). Both HMAs and IAP antagonists show immunomodulatory anti-cancer potential in preclinical studies.

Aims: Here we have undertaken a biomarker-driven approach to understand the potential for induction of immunogenic forms of cell death, such as necroptosis, by rational combination of our clinical compounds in
preclinical models of TCL.

Methods: On-target effects of decitabine and tolinapant were measured by analysing levels of DNMT1 and cIAP1,respectively, by Western blotting in mouse and human cell lines. Levels of key necroptosis biomarkers (RIPK3, MLKL) were also monitored by Western blotting to provide evidence of lytic cell death contributing to a potential immune response. Karpas-299 cells genetically-manipulated to express RIPK3 were used to demonstrate involvement of necroptosis in drug-induced cell death (Cytotox NIR) in vitro. Cell death was monitored by viability (CellTiterGlo)or real-time microscopy (IncuCyte) assays. Levels of key immunomodulatory mediators or DAMPS were measured in tissue culture supernatants and mouse plasma. Levels of methylation in RIPK3 promoter regions were measured by pyrosequencing after bisulfite conversion. Comparative changes in gene expression were measured by RT-qPCR.

Results:
TCL cell lines treated with tolinapant, decitabine or both led to depletion of cIAP1 and DNMT1 in TCL cell lines,
demonstrating target engagement of both agents. The combination of tolinapant and decitabine synergistically
reduced viability of some human T-cell lymphoma cell lines.
Some cell lines, including Karpas-299, were resistant to tolinapant treatment and showed low expression of RIPK3,
which was found to be due to promoter methylation. Increased expression of RIPK3 in Karpas-299 by genetic
manipulation or by decitabine treatment resulted in enhanced lytic cell death upon tolinapant treatment.
Decitabine and tolinapant treatments resulted in expression of cytokines, chemokines and DAMPs, suggesting
potential for immune activation and the effects were enhanced when combined. Furthermore, normally silenced
cancer/testis antigen expression was increased by decitabine, potentially increasing the immunogenicity of the cells.
Evaluation of the combination of agents in mouse models suggested that increased necroptosis signal and immune-potentiating biomarker modulation can be achieved in vivo.

Summary/Conclusion: These data demonstrate that hypomethylating agents enhance immunogenic cell death induced by tolinapant through the re-expression of genes in the necroptotic pathway. In addition, modulation of cytokine response and cancer/testis antigen expression could enhance anti-tumour response. These findings provide a strong rationale to explore this combination clinically.

2022 ASCO: A First-in-Human, Phase 1 Study of ASTX029, a Dual-Mechanism Inhibitor of ERK1/2, in Relapsed/Refractory Solid Tumors

View Poster:

A First-in-Human, Phase 1 Study of ASTX029, a Dual-Mechanism Inhibitor of ERK1/2, in Relapsed/Refractory Solid Tumors

Abstract:

Background: Aberrant activation of the RAS-RAF-MEK-ERK pathway is common in human cancers. This is an open-label Phase 1 study of ASTX029, a dual-mechanism extracellular signal-regulated kinase 1/2 (ERK1/2) inhibitor, in subjects with relapsed/refractory solid tumors (NCT03520075).

Methods: The primary objective is to identify a recommended Phase 2 dose. Subjects with relapsed/refractory solid tumors were eligible for Phase 1A with any molecular feature and for Phase 1B if the tumor demonstrated RAS or BRAF mutations. ASTX029 was administered orally daily on a continuous basis in 21-day cycles. Phase 1A was a modified 3+3 dose-escalation design based on dose-limiting toxicity (DLT) events. Phase 1B subjects were treated at the recommended dose for expansion (RDE) based on emerging safety, pharmacokinetic (PK), and pharmacodynamic (PD) data. Disease response was evaluated by RECIST v1.1.

Results: 76 subjects were treated with at least one dose of ASTX029 in Phase 1A (n = 56) and Phase 1B (n = 20). In Phase 1A, ASTX029 was evaluated from 10 mg to 280 mg daily. Two subjects experienced grade 2 central serous retinopathy (CSR) within a few days of dosing at the 280 mg daily dose level (one event was declared a DLT). Both subjects recovered to baseline within days of dose interruption. CSR is an expected AE based on the class of drugs. At the selected RDE dose level of 200 mg daily, the mean PK exposure was 109% of target exposure (13,022 ng*hr/ml), defined as the level expected to have biological activity based on mouse models. As of the data cut-off of February 7, 2022, the most frequent grade ≥2 AEs experienced by subjects (≥5%) assessed as related to ASTX029 included ocular AEs (n = 6: all Grade 2); nausea (n = 7: all Grade 2); diarrhea (n = 6: 5 Grade 2, 1 Grade 3); fatigue (n = 4: all Grade 2); rash (n = 4, 3 Grade 2, 1 Grade 3). There were 52 serious AEs, all unrelated to ASTX029 except for one subject with Grade 3 malaise. Four subjects had a partial response, including KRAS-G12A BRAF-D549N non-small cell lung cancer (NSCLC; Phase 1A: 120 mg treated 20.0 months); KRAS-G12D pancreatic cancer (Phase 1A: 200 mg treated 2.1 months); KRAS-G13D NSCLC (Phase 1B; treated 10.6 months); KRAS-G12S NSCLC (Phase 1B; treated 10.4 months and ongoing). In all, two partial responses were observed out of 3 NSCLC subjects enrolled in Phase 1B. Phospho-ERK and phospho-RSK were evaluated for PD effect on fresh tumor biopsies obtained at baseline and cycle 2. A PD effect and decreased cell proliferation (Ki-67) were observed in 6 of 9 and 3 of 8 evaluable Phase 1B samples, respectively. The most common reason for ASTX029 discontinuation was disease progression.

Conclusions: This Phase 1 study of the ERK1/2 inhibitor ASTX029 has identified a dose level of 200 mg daily continuously for investigation in the Phase 2 study. PK and PD data suggest target exposures are achieved with preliminary clinical activity, especially in KRAS-mutated NSCLC. Clinical trial information: NCT03520075.

2021 EORTC: Treatment with the dual mechanism ERK inhibitor, ASTX029, alters myeloid cell differentiation

View Poster:

Treatment with the dual mechanism ERK inhibitor, ASTX029, alters myeloid cell differentiation

Abstract:

The inhibition of aberrant MAPK pathway activity is a clinically validated approach which has resulted in the approval of agents targeting tumors driven by activating mutations in BRAF and KRAS. Although the overall response rate to MAPK-targeting agents is high, duration of response is often limited by the emergence of acquired resistance. In contrast, immune checkpoint inhibitors (ICI) such as the anti-PD1 therapy, pembrolizumab, have a lower response rate but induce more durable responses. It has been demonstrated that inhibition of aberrant MAPK pathway activity enhances immune activation. For example, preclinical studies show that treatment with the BRAFV600E inhibitor dabrafenib or the KRASG12C inhibitor sotorasib induces a pro-inflammatory tumor microenvironment (TME), which is associated with increased anti-tumor immunity. Further, studies using syngeneic, MAPK-activated in vivo models have demonstrated that the combination of MAPK-targeting agents and ICI results in synergistic inhibition of tumor growth.

ASTX029 is a dual-mechanism ERK1/2 (ERK) inhibitor, inhibiting both the catalytic activity and phosphorylation of ERK, which is currently undergoing clinical development as part of a Phase 1/2 trial in advanced solid tumors (NCT03520075). ASTX029 has good oral bioavailability and shows potent inhibition of tumor growth in preclinical models bearing activating mutations in the MAPK pathway.

We have previously investigated the immunomodulatory effects of ASTX029 using an in vivo syngeneic tumor model and observed that treatment with ASTX029 resulted in a pro-inflammatory TME, with increased interferon signaling consistent with published data describing the effects of treatment with dual-mechanism ERK inhibitors (Kidger et al., Mol Cancer Ther, 2020). We also observed an increased expression of antigen presentation genes. Using digital spatial profiling, we evaluated the expression of 31 proteins in immune infiltrates and observed a significant decrease in CD14 and a significant increase in MHC class II in ASTX029-treated tumors compared to untreated tumors. We therefore investigated the immunomodulatory effects of ASTX029 using primary human monocytes under conditions that induce macrophage differentiation and polarisation. Treatment with ASTX029 induced a decrease in CD14 and an increase in MHC class II cell surface expression, consistent with our previous in vivo mouse model data. In addition, we observed changes in cell surface expression of phenotypic markers, such as CD206, following treatment with ASTX029.

These data support our previous observations and demonstrate that ERK inhibition by ASTX029 leads to phenotypic changes during monocyte to macrophage differentiation. Our data provide a strong rationale for the combination of ASTX029 with agents which aim to modulate the myeloid compartment or response to myeloid signaling.

2021 ASH: Efficacy of Oral Decitabine/Cedazuridine (ASTX727) in the CMML Subgroup from ASCERTAIN Phase 3 Study

View Poster:

Efficacy of Oral Decitabine/Cedazuridine (ASTX727) in the CMML Subgroup from the ASCERTAIN Phase 3 Study

Abstract:

Background/Introduction: Chronic Myelomonocytic Leukemia (CMML) is an uncommon MDS/MPN overlap syndrome that has historically been included under the umbrella of myelodysplastic syndromes (MDS) for clinical trial and treatment. As a result, DNA methyltransferase inhibitors (DNMTi) such as decitabine or azacitidine have been the established standard of care for the treatment of CMML. The oral bioavailability of these agents has been limited due to rapid degradation by cytidine deaminase (CDA) in the gut and liver so treatment has required intravenous infusion or subcutaneous injections daily for 5-7 days every month (m) adding significant burden to older cancer patients due to daily time commitment and travel to treatment centers. In the context of pandemic SARS-CoV-2, parenteral therapy also increases contact with medical settings with increased infection risk. Oral decitabine 35 mg/cedazuridine 100 mg (ASTX727) is an oral fixed dose combination of decitabine and the CDA inhibitor cedazuridine that produced equivalent exposure (99%; 90% CI 93% to 106%) to IV decitabine 20 mg/m in a randomized cross-over study (Garcia-Manero et al, ASH 2019), and Median overall survival (mOS) for the entire study population in the ASCERTAIN study was approximately 32 months (Savona, 2021). Here, we present outcome data for this study for the enrolled subpopulation of patients with CMML.

Methods: We used a randomized cross over design in which patients were randomized in the first 2 cycles 1:1 to either Sequence A: (decitabine 35 mg/ cedazuridine 100 mg in Cycle 1 followed by IV decitabine at 20 mg/m in Cycle 2), or Sequence B: (IV decitabine in Cycle 1 followed by oral decitabine/cedazuridine in Cycle 2). We conducted an intra-patient comparison of decitabine PK (primary PK endpoint: decitabine AUC equivalence over 5 days of dosing). Cycles were repeated every 28 days (unless delays were needed). All patients received oral decitabine/cedazuridine in Cycles 3 and above until disease progression or unacceptable toxicity. Patients were eligible per the FDA-approved label of IV decitabine (MDS patients by FAB classification including CMML, or MDS IPSS Intermediate-1, 2 or high-risk patients). Clinical endpoints were best response according to International Working Group (IWG) 2006 response criteria, transfusion independence for at least 8 or 16 consecutive weeks, overall survival, and safety. Adverse events (AEs) were graded by Common Terminology Criteria for Adverse Events (CTCAE) v 4.03.

Results: Of the 133 patients enrolled and treated in ASCERTAIN, 16 (12%) had a diagnosis of CMML with demographics and as follows:  median age 71.5 years, 69%Male/31%Female, median weight 87kg (range 65-124), 25%ECOG 0, 75% ECOG 1. Population disease characteristics were: 19% poor or intermediate risk cytogenetics, with median baseline hemoglobin 90 g/L, neutrophils 1.27 X 109/L, platelets 84 x 109/L, bone marrow blasts 5%, with 38% RBC transfusion dependent. Patients received a median of 7 cycles of therapy (range 3-24). Treatment-emergent adverse events of CTCAE Grade 3 or higher in > 10% of patients, independent of relationship to ASTX727, were cytopenias (neutropenia [69%], thrombocytopenia [63%], anemia [56%], leukopenia [19%]), febrile neutropenia (31%), fatigue (13%). Two patients (12.5%) had Complete responses (CR), 8 (50%) had marrow CR ([mCR], including 3 (19%) with hematologic improvement (HI); Overall response rate (ORR) [CR + PR+ mCR + HI] was 75%. Of six patients with baseline RBC transfusion dependence 3 (50%) became transfusion independent. Leukemia-free survival was 28.2 months and after a median follow up of more than 33 months, median overall survival had not been reached. Two patients (13%) went on to Hematopoietic Stem Cell Transplant (HCT).

Conclusions: In the overall study, oral decitabine/cedazuridine delivered equivalent PK exposure to 5 days of IV decitabine 20mg/m2 with a resultant clinical activity safety and efficacy profile in CMML patients consistent with the published literature (e.g. Zeidan, et al 2017) and the Phase 2 experience. The use of oral decitabine/cedazuridine is a reasonable approach in CMML patients.

References:
Garcia-Manero, et al ASH 2019
Savona, et al, Int. MDS Symposium, 2021
Zeidan, et al, Cancer 2017: 3754-3762.

2021 ASH: Combining the IAP Antagonist Tolinapant with a DNA Hypomethylating Agent Enhances Immunogenic Cell Death in Preclinical Models of T-Cell Lymphoma

View Poster:

Combining the IAP Antagonist Tolinapant with a DNA Hypomethylating Agent Enhances Immunogenic Cell Death in Preclinical Models of T-Cell Lymphoma

Abstract:

Introduction:  Tolinapant is a potent, non-peptidomimetic antagonist of cIAP1, cIAP2 and XIAP.  In ongoing Phase 2 trial (NCT02503423), tolinapant has shown activity against highly pre-treated peripheral and cutaneous T-cell lymphoma (Samaniego et al., Hematological Oncology, 2019). Hypomethylating agents (HMAs) have also shown clinical responses in some subsets of PTCL (Lemonnier et al., Blood, 2019). Both HMAs and IAP antagonists show immunomodulatory anti-cancer potential in pre-clinical studies. A Phase 1 clinical study investigating the combination of tolinapant and ASTX727 (oral decitabine) in AML is currently in progress (NCT04155580). Here we have undertaken a biomarker-driven approach to understand the potential for induction of immunogenic forms of cell death (ICD), such as necroptosis, by rational combination of our clinical compounds in pre-clinical models of T-cell lymphoma (TCL).

Methods:  On-target effects of decitabine and tolinapant were measured by analysing levels of DNMT1 and cIAP1, respectively, by Western blotting in mouse and human cell lines. Levels of key apoptosis, necroptosis or pyroptosis biomarkers were also monitored by Western blotting to provide evidence of lytic cell death contributing to a potential immune response. RIPK3- or MLKL-knockout cell lines were generated by CRISPR to demonstrate involvement of necroptosis in drug-induced cell death in a T-cell lymphoma cell line (BW5147.G.1.4) in vitro. Cell death was monitored by viability (CellTiterGlo) or real-time microscopy (IncuCyte) assays. Levels of key inflammatory mediators or DAMPS were measured in tissue culture supernatants and mouse plasma by Luminex assay (Ampersand).

Results:  Combined treatment of tolinapant and decitabine led to depletion of cIAP1 and DNMT1 in TCL cell lines, demonstrating on-target activity of tolinapant and decitabine, respectively. The combination of tolinapant and decitabine acted synergistically in mouse and human T-cell lymphoma cell lines to reduce viability in proliferation assays.

Necroptosis was induced by decitabine or tolinapant alone in mouse TCL cell lines with robust activation of the RIPK1/RIPK3/MLKL necroptosis pathway when caspase activity was inhibited, and the combination of both agents enhanced loss of viability.

Furthermore, we demonstrated decitabine treatment led to re-expression of both RIPK3 and MLKL in mouse cell lines, supporting published evidence that methylation can silence these key biomarkers (Koo et al., Cell Research, 2015; Koch et al., Neoplasia, 2021). Enhanced release of chemokine, cytokine and DAMPs was demonstrated with the combination of agents in vitro and in vivo.

By removal of key necroptosis pathway components using CRISPR, we confirmed the importance of this lytic cell death pathway by demonstrating that RIPK3-/- and MLKL-/- T-cell lymphoma (BW5147.G.1.4) cell lines had reduced necroptosis potential after treatment with tolinapant or decitabine alone or in combination; and demonstrate reduced release of inflammatory mediators in vitro.

Finally, our in vivo evaluation of the combination of agents in mouse syngeneic models suggested that increased anti-tumour activity and immune-potentiating systemic biomarker modulation can be achieved with a tolerated dosing regimen of both compounds.

Conclusion:  These data demonstrate that decitabine enhances immunogenic cell death induced by tolinapant through the re-expression of genes in the necroptotic pathway.  This finding provides strong rationale to explore this combination clinically.

2021 ASH: Results from a Global Randomized Phase 3 Study of Guadecitabine (G) Vs Treatment Choice (TC) in 302 Patients with Relapsed or Refractory (r/r) Acute Myeloid Leukemia after Intensive Chemotherapy (ASTRAL-2 Study)

View Poster

Results from a Global Randomized Phase 3 Study of Guadecitabine (G) Vs Treatment Choice (TC) in 302 Patients with Relapsed or Refractory (r/r) Acute Myeloid Leukemia after Intensive Chemotherapy (ASTRAL-2 Study)

Abstract:

Background: Guadecitabine (G) is a next generation subcutaneous (SC) hypomethylating agent (HMA) resistant to degradation by cytidine deaminase which results in prolonged in vivo exposure to the active metabolite decitabine. We conducted a large global randomized phase 3 study (ASTRAL-2) of G vs TC in AML patients who were either refractory to or relapsed (r/r) after prior anthracycline-based intensive chemotherapy with or without hematopoietic cell transplant (HCT).

Methods:  r/r AML patients were randomized to G (60 mg/m2 SC/d for 10 days in first 1-2 cycles followed by 5-day cycles Q 28 days) vs Treatment Choice (TC). TC were preselected prior to randomization to either low intensity (LI) treatment; high intensity (HI) chemotherapy; or Best Supportive Care (BSC).  LI choices were other HMAs of azacitidine or decitabine, or low-dose Ara-C (LDAC) at their standard doses. HI choices were high-dose Ara-C (HiDAC), MEC, or FLAG± Ida combination chemotherapy at standard doses. Primary endpoint was overall survival (OS) based on ITT analysis with secondary endpoints including 12 and 24-month survival rates, complete response (CR), event-free survival (EFS), and safety. P values for secondary endpoints and subgroups are nominal as there was no adjustment of p values for multiple analyses.

Results: 302 patients were randomized to G (148) or TC (154). Preselected TCs were mainly LI (77%) predominantly HMAs (86% of the patients randomized to LI), or HI (21%), with only 6 patients (2%) in the BSC subset. Baseline variables were well balanced across the 2 treatment arms. For G vs TC respectively, age ≥65 y in 51.4% vs 40.3% with median age 65y vs 63y, ECOG PS 2 in 15.5% vs 20.8%, poor risk cytogenetics in 44.6% vs 42.2%, refractory AML in 44.6% vs 33.1%, prior HCT in 18.2% vs 26%, a majority of patients were in second or subsequent relapse after ≥ 2 prior therapies (54.7% vs 56.5%).

Median number of treatment cycles was short (3 cycles for G vs 2 cycles for TC). Median follow up was 21.6 months.  Most common causes of treatment discontinuation were disease progression (35.2% for G vs 38.1% for TC), or death (15.2% for G vs 18.4% for TC).

Median OS on G was 6.4 months vs 5.4 months for TC and not statistically significant (OS HR 0.88, 95% CI 0.67, 1.14, log rank p value 0.3). There was no significant difference in OS between G and each of the LI and HI preselected subsets. However, several other planned prospective subgroups favored G with OS HR 95% CI upper limit ≤ 1.0 including patients <65y (HR 95% CI 0.47, 0.97, p 0.032) ; ECOG PS 0-1 (HR 95% CI 0.57, 1.0, p 0.049); refractory AML (HR 95% CI 0.38, 0.89, p 0.013); lower peripheral blood (PB) disease burden of ≤ 30% PB blasts (HR 95% CI 0.46, 0.92, p 0.015); and those who received at least 4 cycles in either treatment arm (HR 95% CI 0.36, 0.95, p 0.031).  The 12- and 24-month survival rates for G vs TC respectively were 32% vs 26%; and 19% vs 10%.  Median EFS was short with 3 months for G vs 2.4 months for TC; log rank p 0.005. CR rate was 12.8% for G vs 7.1% for TC (p 0.051). CR + CR with partial hematologic recovery (CRh) rate was double for G with 16.9% compared to 7.8% for TC (p 0.007). Composite CR (CRc) or CR+ CR with incomplete hematologic recovery (CRi) rate was 27% for G vs 14.3% for TC (p 0.003).

Adverse events (AEs) of grade ≥3, regardless of relationship to treatment, were 89% on G vs 84% on TC. Most common Grade ≥3 AEs for G vs TC respectively were febrile neutropenia (38.6% vs 38.1%); neutropenia (32.4% vs 17%); thrombocytopenia (28.3% vs 29.9%); anemia (21.4% vs 24.5%); pneumonia (18.6% vs 20.4%); and sepsis (11.7 vs 10.9%).  None of the differences were significant except for neutropenia (p 0.003).

Summary/Conclusions: In this randomized study in r/r AML after intensive chemotherapy, G did not significantly improve OS compared to standard of care TC composed mainly of LI treatment with other HMAs. The data suggest that G may be better than TC in in some of the secondary endpoints (24-month survival rate, EFS, CR, CR+CRh, and CRc). Prospective subgroup analyses of OS suggest that younger (<65 y), more fit patients (PS 0-1); with lower PB disease burden (PB blasts ≤ 30%), and those who could receive at least 4 cycles may benefit from G. The results of secondary endpoints and subgroup analyses should be interpreted with caution. Grade ≥3 AEs were the expected hematological and infection AEs with no significant differences between G and TC except for significantly higher incidence of neutropenia with G.

2021 ASH: Oral decitabine/cedazuridine in Patients with Lower Risk Myelodysplastic Syndrome: a Longer-Term Follow-Up of from the ASCERTAIN Study

View Poster
Oral decitabine/cedazuridine in Patients with Lower Risk Myelodysplastic Syndrome: a Longer-Term Follow-Up of from the ASCERTAIN Study

Abstract:
Background/Introduction: Lower-risk (IPSS low risk and Int-1) myelodysplastic syndromes (MDS) are typically treated supportively to address cytopenias. DNA methyltransferase inhibitors (DNMTi) such as azacitidine and decitabine (DEC) are FDA-approved for higher risk MDS patients (pts), and while the DEC USPI includes IPSS Int-1 pts, it is not widely used in this population. Approved intravenous (IV) or subcutaneous (SC) regimens require 5-7 days of treatment every month burdening older cancer pts due to daily travel and treatment time and may increase potential risk from pandemic SARS-CoV-2 infection. Because DNMTis are rapidly degraded by cytidine deaminase (CDA) in the gut and liver, oral availability has only been recently possible. A randomized study with CC-486, an oral formulation of azacitidine, in the Int-1 population showed a median overall survival (mOS) of approximately 17 months for both placebo and treated patients (Garcia-Manero, 2021). Oral DEC 35 mg/cedazuridine 100 mg (ASTX727) or DEC-C, is an oral fixed dose combination (FDC) of DEC and the CDA inhibitor cedazuridine (CED) resulting in equivalent exposure (99%; 90% CI 93% to 106%) to standard IV DEC 20 mg/m2 for 5 days in an intra-patient randomized cross-over study (Garcia-Manero et al, ASH 2019). Here, we present data on patients with lower risk MDS from that study.
Methods: We used a randomized cross over design with pts randomized 1:1 in the first 2 cycles to either Sequence A: (DEC 35 mg/ CED 100 mg in Cycle 1 and IV DEC at 20 mg/m2 in Cycle 2), or Sequence B (IV DEC in Cycle 1 and oral DEC/CED in Cycle 2). Cycles were repeated every 28 days unless delays were needed, and all patients received oral DEC-C in Cycles 3+ until disease progression or unacceptable toxicity. We conducted an intra-patient comparison of DEC PK (DEC AUC equivalence over 5 days of dosing). Pts were eligible as per the FDA-approved label of IV DEC (MDS pts by FAB classification including CMML, or MDS IPSS Intermediate-1, 2 or high-risk pts). Clinical endpoints were best response as assessed by an independent expert panel according to IWG 2006 response criteria, transfusion independence (TI), overall survival (OS), and safety.
Results: Of the 133 pts treated in ASCERTAIN, 69 had a diagnosis of lower-risk MDS (93% Int-1, 7% LR). Median age was 70.0 years (range 45-87), 65% were male, median weight was 84 kg (range 50-127), median baseline hematologic parameters were: hemoglobin 89 g/L (range 69.8-146.5), WBCs 1.50 X 109/L (range 0.11-7.1), platelets (plt) 86 x 109/L (range 5-703), bone marrow blasts 4% (range 0-18), cytogenetics: 7 (10.1%) poor-risk, 21 (30.4%) intermediate risk, 37 (53.6%) better-risk, 4 (5.7%) missing or not evaluable. 27(39%) of the pts were RBC transfusion dependent (TD) and 6 (9%) plt TD. 17 (25%) had received prior MDS treatment, 3% prior DNMTi. Pts received a median of 9 cycles of therapy (range 1-28). Treatment-emergent adverse events of CTCAE Gr 3 or higher in >10% of pts, independent of relationship to ASTX727, included cytopenias (neutropenia [59%], thrombocytopenia [58%], anemia [48%], leukopenia [26%]), febrile neutropenia (32%), and pneumonia (19%). Sixteen pts (23%) achieved Complete Response (CR), 18 (26%) had marrow CR (mCR), including 9 (13%) with hematologic improvement (HI). Overall Response rate (ORR; CR + PR+ mCR + HI) was 57%. Of those RBC or plt TD at baseline, 13 (48%) became RBC TI and 4 (67%) became plt TI. With approximately 32 months of median follow up, neither median leukemia-free survival (mLFS) nor mOS had been reached (Figure 1). Twelve pts (17%) went on to allogeneic stem cell transplant.
Conclusions: Oral decitabine/cedazuridine given as a FDC in MDS pts produced equivalent PK exposure to 20 mg/m2 IV DEC; in lower risk MDS pts with treatment indicated, the agent was generally well-tolerated with prolonged treatment and could result in mLFS and mOS which exceeds 32 months. This FDC and other dosing regimens of oral DEC-C should be further studied in this patient population.
References:
Garcia-Manero, et al, ASH 2019
Savona, et al, Int. MDS Symp. 2021
Garcia-Manero, et al,. J. Clin. Onc. 2021 39:13, 1426-1436