Inhibitor Duvelisib Research Articles

PI3K Inhibitors in Hematology: When One Door Closes….

The PI3K signaling pathway regulates key cellular processes and is one of the most aberrantly activated pathways in cancer. The class I PI3K catalytic subunits p110γ and p110δ are highly enriched in leukocytes, providing an additional rationale for targeting these PI3Ks in hematologic malignancies. In 2014, the PI3Kδ inhibitor idelalisib was the first of four PI3K inhibitors (PI3Ki) to receive regulatory approval for relapsed B-cell malignancies. This was followed by approvals of the pan-class I inhibitor copanlisib (2017), the dual PI3Kγ/δ inhibitor duvelisib (2018), and the PI3Kδ and casein kinase 1ε inhibitor umbralisib (2021). Copanlisib and umbralisib received accelerated approvals, whereas idelalisib and duvelisib received initial accelerated approvals followed by full approvals. The accelerated approvals were based on overall response rates; however, follow-up studies showed increased risk of death and serious side effects. Furthermore, the confirmatory trial with copanlisib failed to show an improvement in progression-free survival when compared with chemoimmunotherapy. These developments led to black box warnings for idelalisib and duvelisib and withdrawal of copanlisib and umbralisib from the market by their manufacturers. Given the uncertain future of this drug class, additional manufacturers terminated ongoing phase III trials with novel PI3Kis. In this study, we review the development and current status of PI3Kis in hematology, limitations to their use, and our perspective on whether there is a future for PI3Kis in hematology.

Duvelisib plus romidepsin in relapsed/refractory T cell lymphomas: a phase 1b/2a trial.

PI3K-δ inhibitors have shown impressive activity in lymphoid malignancies but have been hampered by autoimmune and infectious toxicities, leading to market withdrawals. We previously demonstrated activity of the PI3K-δγ inhibitor duvelisib in T cell lymphomas (TCLs) that was associated with inflammatory adverse events. As reported here, we conducted a phase 1b/2a study of duvelisib in combination with either romidepsin (n = 66) or bortezomib (n = 32) in patients with relapsed/refractory TCL and found that the addition of romidepsin, but not bortezomib, appeared to increase efficacy while attenuating PI3K inhibitor-driven toxicity. The primary endpoint of the study was to determine the safety and maximum tolerated dose of duvelisib, which was 75 mg twice daily when combined with romidepsin versus 25 mg twice daily when combined with bortezomib. The most common adverse events were neutropenia (42%, 25/59) and fatigue (37%, 22/59) in patients treated with duvelisib and romidepsin and diarrhea (48%, 11/23) and neutropenia (30%, 7/23) in patients treated with duvelisib and bortezomib. Duvelisib and romidepsin resulted in less grade 3/4 hepatotoxicity (14%, 8/59) compared to 40% (14/35) in our previous study with duvelisib monotherapy. This was associated with reductions in circulating inflammatory mediators and myeloid cell inflammatory gene expression. Secondary endpoints of overall and complete response rates were 55% (35/64) and 34% (22/64) for patients treated with duvelisib and romidepsin and 34% (11/32) and 13% (4/32) for patients treated with duvelisib and bortezomib. Among patients with peripheral T cell lymphomas (PTCLs), overall and complete response rates of duvelisib and romidepsin were 56% (27/48) and 44% (21/48), respectively, with exploratory analyses showing increased response rates in patients with a follicular helper T cell subtype. These findings support further development of combined PI3K and histone deacetylase (HDAC) inhibition in TCLs and suggest a unique strategy to enable PI3K inhibitor-based combinations for additional patient populations. ClinicalTrials.gov identifier: NCT02783625 .

KLRG1 Cell Depletion as a Novel Therapeutic Strategy in Patients with Mature T-Cell Lymphoma Subtypes.

Develop a novel therapeutic strategy for patients with subtypes of mature T-cell and NK-cell neoplasms. Primary specimens, cell lines, patient-derived xenograft models, commercially available, and proprietary anti-KLRG1 antibodies were used for screening, target, and functional validation. Here we demonstrate that surface KLRG1 is highly expressed on tumor cells in subsets of patients with extranodal NK/T-cell lymphoma (ENKTCL), T-prolymphocytic leukemia (T-PLL), and gamma/delta T-cell lymphoma (G/D TCL). The majority of the CD8+/CD57+ or CD3-/CD56+ leukemic cells derived from patients with T- and NK-large granular lymphocytic leukemia (T-LGLL and NK-LGLL), respectively, expressed surface KLRG1. The humanized afucosylated anti-KLRG1 monoclonal antibody (mAb208) optimized for mouse in vivo use depleted KLRG1+ TCL cells by mechanisms of ADCC, ADCP, and CDC rather than apoptosis. mAb208 induced ADCC and ADCP of T-LGLL patient-derived CD8+/CD57+ cells ex vivo. mAb208 effected ADCC of subsets of healthy donor-derived KLRG1+ NK, CD4+, CD8+ Tem, and TemRA cells while sparing KLRG1- naïve and CD8+ Tcm cells. Treatment of cell line and TCL patient-derived xenografts with mAb208 or anti-CD47 mAb alone and in combination with the PI3K-δ/γ inhibitor duvelisib extended survival. The depletion of macrophages in vivo antagonized mAb208 efficacy. Our findings suggest the potential benefit of a broader treatment strategy combining therapeutic antibodies with PI3Ki for the treatment of patients with mature T-cell and NK-cell neoplasms. See related commentary by Varma and Diefenbach, p. 2300.

A Phase II Study of Intermittent Duvelisib Dosing in Patients with Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma (CLL/SLL)

Background. Targeting phosphatidylinositol 3-kinase (PI3K) has emerged as an efficacious approach for treatment of chronic lymphocytic leukemia (CLL) and non-Hodgkin lymphoma (NHL). However, toxicities of the PI3K inhibitors are an important concern limiting their use. Duvelisib is a potent oral inhibitor of both the PI3K-δ and PI3K-γ isoforms with proven efficacy in CLL/SLL. Here we report the results of a phase 2 study evaluating efficacy and safety of duvelisib with intermittent dosing in patients with relapsed/refractory CLL/SLL Methods. This open-label, single arm, phase 2 study enrolled patients with CLL/SLL treated with at least 1 prior line of therapy with active disease as defined by the iWCLL 2008 criteria. Duvelisib was given at a dose of 25 mg PO BID for 28-day cycles for a total of 12 weeks during the induction phase, followed by 75 mg PO BID 2 days on and 5 days off for repeated 28-day cycles during the maintenance phase until death, intolerance or disease progression. The primary endpoint was progression free survival (PFS) at 12 months; secondary endpoints were safety and clinical benefit. The trial was originally planned to enroll 27 patients but was stopped early due to difficulties with enrollment following changing FDA guidance for the use of PI3K inhibitors. Results. Fifteen patients were enrolled. Median age was 74 (59-82) years, 8/15 (53%) were female; patients were primarily Caucasian (13/15; 87%); performance status was 0-1, with 27% (4/15) ECOG 0 and 73% (11/15) ECOG 1. This was a heavily pre-treated patient population with a median of 3 prior lines of therapy (1-6). Among patients where results were available, 79% (11/14) had abnormal FISH results including 36% with TP53 gene loss, 27% del(13q), and 18% del(11q). Sixty-seven percent (8/12) had unmutated IGHV. Of the 15 patients treated, 4 were not evaluable for efficacy due to coming off study early for toxicity (2), development of MDS unrelated to study drug (1) or death due to complications from COVID-19 infection (1). Among the 11 efficacy-evaluable patients, 82% achieved PR, and 18% had stable disease. The 12-month PFS was 43% (95%CI: 18%-66%) and the median PFS was 9.9 months (95% CI: 5.5-NA). Among the 9 responders, the median duration of response (DOR) was 5.3 months (95%CI: 1.9-NA) and 12-month DOR was 22% (95%CI:3%-51%). Five patients (33%) discontinued therapy due to adverse events, which occurred during the induction phase in 4/5 of the patients. Five patients (33%) discontinued due to progressive disease - all during the maintenance phase of treatment. Additionally, 2 patients discontinued due to MD decision; one patient developed MDS which was unrelated to duvelisib; one patient died during treatment due to complications from COVID-19. Treatment was generally well tolerated with the most common grade 3 or higher adverse events being leukocytosis (20%), alanine aminotransferase (ALT) increase (13%), aspartate aminotransferase (AST) increase (13%), oral mucositis (13%) and colitis (13%). The adverse events leading to treatment discontinuation occurred primarily during induction. The most common adverse events of any grade included fatigue in 5 patients (33%), leukocytosis, vomiting, ALT increase, AST increase, diarrhea, and elevation of alkaline phosphatase, which occurred in 4 patients each (27%). Conclusions. We report the results of an open-label, phase 2 study utilizing a continuous dosing induction phase followed by an intermittent dosing maintenance phase of the PI3K inhibitor duvelisib in patients with relapsed/refractory CLL/SLL. Patients who received duvelisib on an intermittent schedule achieved some clinical benefit, however, the desired 12-month PFS goal of 50% was not reached. Adverse events in general were manageable and mainly related to gastrointestinal and liver toxicity, and patient died during treatment from complications from COVID-19 pneumonia. After an initial 12 weeks of continuous duvelisib treatment, the incorporation of intermittent dosing appears to be a viable option for patients with previously treated CLL/SLL.

Targeting CCR7-PI3Kγ overcomes resistance to tyrosine kinase inhibitors in ALK-rearranged lymphoma.

Anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitors (TKIs) show potent efficacy in several ALK-driven tumors, but the development of resistance limits their long-term clinical impact. Although resistance mechanisms have been studied extensively in ALK-driven non-small cell lung cancer, they are poorly understood in ALK-driven anaplastic large cell lymphoma (ALCL). Here, we identify a survival pathway supported by the tumor microenvironment that activates phosphatidylinositol 3-kinase γ (PI3K-γ) signaling through the C-C motif chemokine receptor 7 (CCR7). We found increased PI3K signaling in patients and ALCL cell lines resistant to ALK TKIs. PI3Kγ expression was predictive of a lack of response to ALK TKI in patients with ALCL. Expression of CCR7, PI3Kγ, and PI3Kδ were up-regulated during ALK or STAT3 inhibition or degradation and a constitutively active PI3Kγ isoform cooperated with oncogenic ALK to accelerate lymphomagenesis in mice. In a three-dimensional microfluidic chip, endothelial cells that produce the CCR7 ligands CCL19/CCL21 protected ALCL cells from apoptosis induced by crizotinib. The PI3Kγ/δ inhibitor duvelisib potentiated crizotinib activity against ALCL lines and patient-derived xenografts. Furthermore, genetic deletion of CCR7 blocked the central nervous system dissemination and perivascular growth of ALCL in mice treated with crizotinib. Thus, blockade of PI3Kγ or CCR7 signaling together with ALK TKI treatment reduces primary resistance and the survival of persister lymphoma cells in ALCL.

In vivo activity of the dual PI3Kδ and PI3Kγ inhibitor duvelisib against pediatric acute lymphoblastic leukemia xenografts.

Acute lymphoblastic leukemia (ALL) remains one of the most common causes of cancer-related mortality in children. Phosphoinositide 3-kinases (PI3Ks) are a family of lipid kinases, and aberrations in the PI3K pathway are associated with several hematological malignancies, including ALL. Duvelisib (Copiktra) is an orally available, small molecule dual inhibitor of PI3Kδ and PI3Kγ, that is Food and Drug Administration (FDA) approved for the treatment of relapsed/refractory chronic lymphocytic leukemia and small lymphocytic lymphoma. Here, we report the efficacy of duvelisib against a panel of pediatric ALL patient-derived xenografts (PDXs). Thirty PDXs were selected for a single mouse trial based on PI3Kδ (PIK3CD) and PI3Kγ (PIK3CG) expression and mutational status. PDXs were grown orthotopically in NSG (NOD.Cg-Prkdcscid IL2rgtm1Wjl /SzJAusb) mice, and engraftment was evaluated by enumerating the proportion of human versus mouse CD45+ cells (%huCD45+ ) in the peripheral blood. Treatment commenced when the %huCD45+ reached greater than or equal to 1%, and events were predefined as %huCD45+ greater than or equal to 25% or leukemia-related morbidity. Duvelisib was administered per oral (50mg/kg, twice daily for 28days). Drug efficacy was assessed by event-free survival and stringent objective response measures. PI3Kδ and PI3Kγ mRNA expression was significantly higher in B-lineage than T-lineage ALL PDXs (p-values <.0001). Duvelisib was well-tolerated and reduced leukemia cells in the peripheral blood in four PDXs, but with only one objective response. There was no obvious relationship between duvelisib efficacy and PI3Kδ or PI3Kγ expression or mutation status, nor was the in vivo response to duvelisib subtype dependent. Duvelisib demonstrated limited in vivo activity against ALL PDXs.

Roles of PI3Kγ and PI3Kδ in mantle cell lymphoma proliferation and migration contributing to efficacy of the PI3Kγ/δ inhibitor duvelisib

Mantle cell lymphoma (MCL) is an aggressive B-cell non-Hodgkin lymphoma that is incurable with existing therapies, and therefore presents a significant unmet clinical need. The ability of this disease to overcome therapy, including those that target the B cell receptor pathway which has a pathogenic role in MCL, highlights the need to develop new treatment strategies. Herein, we demonstrate that a distinguishing feature of lymph node resident MCL cells is the expression of phosphatidylinositol 3-kinase γ (PI3Kγ), a PI3K isoform that is not highly expressed in other B cells or B-cell malignancies. By exploring the role of PI3K in MCL using different PI3K isoform inhibitors, we provide evidence that duvelisib, a dual PI3Kδ/γ inhibitor, has a greater effect than PI3Kδ- and PI3Kγ-selective inhibitors in blocking the proliferation of primary MCL cells and MCL cell lines, and in inhibiting tumour growth in a mouse xenograft model. In addition, we demonstrated that PI3Kδ/γ signalling is critical for migration of primary MCL cells and cell lines. Our data indicates that aberrant expression of PI3Kγ is a critical feature of MCL pathogenesis. Thus, we suggest that the dual PI3Kδ/γ duvelisib would be effective for the treatment of mantle cell lymphoma.

Simultaneous Inhibition of PI3Kgamma and PI3Kdelta Deteriorates T-cell Function With Implications for Chronic Lymphocytic Leukemia.

Chronic lymphocytic leukemia (CLL) is a common and incurable B-cell malignancy. Recent therapeutic approaches that target the B-cell receptor signaling pathway include inhibition of phosphatidylinositol-3-kinase (PI3K). The PI3K isoform delta is constitutively active in CLL, making it an attractive therapeutic target. However, the expression of PI3K isoforms is not exclusive to leukemic cells, as other immune cells in the tumor microenvironment also rely on PI3K activity. Subsequently, therapeutic inhibition of PI3K causes immune-related adverse events (irAEs). Here, we analyzed the impact of the clinically approved PI3Kδ inhibitors idelalisib and umbralisib, the PI3Kγ inhibitor eganelisib, and the dual-γ and -δ inhibitor duvelisib on the functional capacity of T cells. All investigated inhibitors reduced T-cell activation and proliferation in vitro, which is in line with PI3K being a crucial signaling component of the T-cell receptor signaling. Further, dual inhibition of PI3Kγ and PI3Kδ showed strong additive effects suggesting a role also for PI3Kγ in T cells. Extrapolation of this data to a clinical setting could provide an explanation for the observed irAEs in CLL patients undergoing treatment with PI3K inhibitors. Consequently, this highlights the need for a close monitoring of patients treated with PI3K inhibitors, and particularly duvelisib, due to their potentially increased risk of T-cell deficiencies and associated infections.

Duvelisib for Critically-Ill Patients with COVID-19 Disease: An Investigator-Initiated, Randomized, Placebo-Controlled Double-Blind Pilot Trial

Background: Severe and critical COVID-19, including acute respiratory distress syndrome (ARDS), cardiomyopathy, and shock, have been associated with a 28-day mortality exceeding 50%. While dexamethasone (dex) improves survival in such patients and highlights a role for anti-inflammatory therapy, mortality remains high especially in those who do not respond initially. Phase II/III studies of the PI3K-d/g inhibitor duvelisib in patients with chronic lymphocytic leukemia or follicular lymphoma have demonstrated that duvelisib significantly downregulates expression of inflammatory cytokines and chemokines (e.g. G-CSF, GM-CSF, macrophage inflammatory protein-1 α and β). These same inflammatory molecules are upregulated in ARDS and COVID-19. Several murine models of acute lung inflammation and sepsis have demonstrated improved markers of inflammation and survival of mice treated with PI3K inhibitors. The original SAR-CoV-1 coronavirus had demonstrated the ability to hijack the PI3K signaling machinery in order to persist within human airway cells. Additionally, in the context of neoplasia, duvelisib polarizes macrophages to the M1 phenotype which has antimicrobial effector functions in contrast to the pro-inflammatory M2 phenotype. In the context of chimeric antigen receptor T (CAR T) therapy, the DiPersio lab has identified duvelisib as a potent mediator of cytokine release syndrome (CRS) without T-cell inhibition, an overlapping concept with COVID-19. We hypothesized that duvelisib could attenuate COVID-19 ARDS and CRS through M1 macrophage polarization, reduction in cytokine signaling/production, and elimination of viral persistence. Methods: We conducted a multicenter, double-blind, placebo-controlled trial in which 28 patients were randomized 1:1 to duvelisib 25mg twice daily or placebo for 10 days. Eligible patients were 18 years or older hospitalized with a primary diagnosis of COVID-19 disease with either respiratory failure (≥ 50% lung involvement by imaging, invasive or non-invasive mechanical ventilation, or extracorporeal membrane oxygenation), new cardiomyopathy, and/or shock requiring vasopressor support. All patients were required to be receiving or have received dex 6mg daily or equivalent for at least 48 hours without improvement. All patients received prophylaxis for Pneumocystis jiroveci. We monitored viral load daily using quantitative RT-PCR to assess for changes in viral replication following initiation of therapy. Primary endpoint was 28-day survival. Secondary endpoints included: 60-day survival; duration on ventilator and vasopressors; hospital and ICU length of stay; viral kinetics; and adverse events. Correlatives included impact on cytokine expression measured by multiplex panel, viral kinetics by RT-PCR, and flow-cytometry to assess immune populations at various time points during therapy. Results: Baseline and disease characteristics were well-balanced with the exception of baseline renal replacement therapy (Table 1). At day 29, 67% of those in the duvelisib arm and 62% of those in the placebo arm were alive. Secondary efficacy endpoints were comparable between the two cohorts. There was a trend toward improved 60-day OS in the duvelisib arm (60% vs. 46%, p = 0.36, Figure 1) and some patients in the treatment arm were noted to have quick radiographic and clinical improvements. Of those on ECMO at initiation 3/5 (60%) in the duvelisib arm and 1/4 (25%) in the placebo arm were successfully weaned. Adverse events (AEs) occurred at similar rates between arms. Among AEs of special interest previously reported with the use of duvelisib, one patient developed colitis ultimately deemed to be stercoral colitis and unrelated to treatment. No CMV reactivation or Pneumocystis jiroveci pneumonia occurred. Eighty percent of overall deaths were due to respiratory failure from disease progression. In the placebo arm, one patient died of Pseudomonas pneumonia and one died of cholecystitis. Conclusion: In our pilot study, duvelisib did not show improvement in 28-day survival in a critically-ill, steroid-refractory population. However, there was a trend toward improved 60-day OS. No added toxicity was observed in those receiving duvelisib. Based on comparable safety, notable improvements in select patients, and a continued unmet need in this population, we believe larger studies are justified. Correlative data will also be presented. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

CD49d Expression Identifies a Biologically Distinct Subtype of Chronic Lymphocytic Leukemia with Inferior Progression Free Survival on BTK Inhibitor Therapy

Background: Acalabrutinib, a highly selective Bruton tyrosine kinase inhibitor (BTKi), is effective and well tolerated for patients with chronic lymphocytic leukemia (CLL). During treatment with BTKis, transient lymphocytosis is observed due to the efflux of CLL cells from lymphoid organs. CD49d, the alpha chain of the CD49d/CD29 integrin very late antigen-4 (VLA-4), is a key mediator in CLL microenvironmental interactions. High CD49d expression has been associated with inferior response to ibrutinib (Tissino, 2018). Here, we investigated the role of CD49d in response to acalabrutinib in 48 patients with CLL enrolled in a single-center, phase 2 study (NCT02337829). Methods: Patients were divided into CD49d positive (CD49d+, n = 27, 56%) and CD49d negative (CD49dneg, n = 21, 44%) groups based on the established 30% cutoff, as assessed by flow cytometry. CD49d activation was measured as VLA-4 receptor occupancy (RO), as described (Tissino, 2018). Time to progression was estimated using the Kaplan-Meier method. RNA sequencing (RNA-seq) of CD19+ selected CLL cells from CD49d+ (n = 10) and CD49dneg (n = 10) subsets was performed at baseline and 6 months on acalabrutinib. Results: After the first month on acalabrutinib, the median increase in absolute lymphocyte count (ALC) for CD49d+ CLL was 6.4% vs. 50.4% for CD49dneg (P = .02). However, the increase in ALC on day 3 of 42% and 48%, respectively, was comparable (P = .8). A subset of patients showed bimodal CD49d (bimCD49d) expression, with concomitant presence of CD49d positive and negative subpopulations. In these cases, the fraction of CD49d+ CLL cells increased significantly on day 3 (P = .002), but decreased at 6 months (P = .004), suggesting that CD49d+ cells may be better able to remain tissue bound on chronic therapy or reenter lymphoid tissues at higher rates than CD49dneg cells. While constitutive VLA-4 activation was reduced in patients on acalabrutinib, BCR and CXCR4 stimulation still increased VLA-4 RO on CLL cells even after 6 months of treatment. PI3K, in addition to BTK signaling, is implicated in inside-out activation of VLA-4. In vitro, addition of the PI3K inhibitor duvelisib to acalabrutinib-treated CLL cells completely blocked BCR- but not CXCR4- induced VLA-4 activation. The overall response rate of the study was 95.8% (Sun, 2020). Sixteen patients progressed at a median of 42.5 months, 3 with transformation. Time to progression for patients with CD49d+ and CD49dneg CLL (applying 30% cutoff) did not differ (P = .4). However, at 72 months 50% of the combined CD49d+ and bimCD49d patients (n = 37) were estimated progression-free vs 90% of patients with a homogeneous CD49dneg CLL population (n = 11, P = .02). Of 13 patients progressing with CLL, 12 (92%) were CD49d+ or bimodal CD49d and 11 (85%) had BTK and/or PLCG2 mutations. To dissect the impact of CD49d expression on CLL pathobiology and the response to acalabrutinib, we compared transcriptomes of CD49d+ and CD49dneg subsets by RNA-seq. A distinct gene expression profile separated the groups by principal component analysis. Using gene set enrichment analysis, CD49d+ CLL showed constitutively more immunoreceptor, NF-kappa B, and cytokine/JAK-STAT signaling, as well as enhanced cell survival, adhesion and migration capacity compared to CD49dneg CLL (FDR <.25). After 6 months on acalabrutinib, all 20 patients achieved a clinical response and all samples showed downregulation of B-cell receptor and NF-kappa B target genes, as expected for BTKi therapy. Interestingly, on acalabrutinib, CD49d+ samples not only maintained a higher level of activation compared to CD49dneg CLL, but differences in the degree of cytokine (IL-6, IL-10) and STAT3 signaling became more prominent. Conclusion. CD49d+ and CD49dneg CLL cells are rapidly mobilized out of lymph nodes at the start of acalabrutinib therapy, but CD49d+ cells appear able to reenter or persist in lymphoid tissues better than CD49dneg cells. Bimodal CD49dneg and CD49d+ cases share an increased risk of disease progression, with most patients having detectable BTK or PLCG2 mutations at the time of progression. The transcriptional program of CD49d+ CLL reflects upregulation of survival and activation pathways that may increase tolerance to BTKi therapy and set the stage for clonal evolution. Thus, CD49d/VLA-4 emerges as a microenvironmental factor that contributes to BTKi resistance and a possible therapeutic target to improve on BTKi therapy.

PI3Kδ/γ Inhibitor Duvelisib Modulates Inflammatory Profile in Severe COVID-19 Patients: Results from a Randomized Placebo-Controlled Phase 2 Study

Background: ARDS following SARS-CoV-2 infection (COVID-19) is associated with the development of a hyper-inflammatory cytokine storm. Several anticancer drugs were repurposed for COVID-19 investigational treatment due to their favorable effect on immune profiles. Duvelisib (Copiktra, IPI-145, DUV) is an FDA-approved oral PI3K delta/gamma (PI3Kδ/γ) inhibitor for treating relapsed or refractory CLL/SLL and FL. PI3Kδ/γ inhibitors promote the formation of a pool of T-cells with a memory phenotype by inhibiting aerobic glycolysis, preventing T-cell activation-mediated terminal differentiation and exhaustion. Therefore, we hypothesized that duvelisib might limit hyperactivation of the immune system and mitigate T-cell exhaustion, promoting more effective anti-viral responses to SARS-CoV-2 and limiting the progression of COVID-19. Methods: DAMPEN-CI was a single-center randomized placebo-controlled phase 2 study evaluating the efficacy of duvelisib, a PI3Kδ/γ inhibitor, in reducing inflammation and the incidence of respiratory failure in non-intubated adults with severe (RR>30, HR>125, O2 sat<93%, and PaO2/FiO2<300) PCR- and X-Ray-confirmed COVID-19 pneumonia. Pts were analyzed per-protocol. The primary endpoints were the fraction of subjects who required mechanical ventilation or died within 29 days of randomization. Critical secondary endpoints included serious adverse events (SAE, Grade 3/4), ICU transfer, duration of hospitalization, oxygen use, inflammatory biomarkers (Ferritin, CRP, d-dimer), and serum cytokine levels (e.g COVID-19 progression related) detected by a high-sensitivity multiplex electrochemiluminescent immunoassay. Safety monitoring included serial blood counts and renal and hepatic function measurements. Results: A total of 47 pts (DUV=25, Placebo=22) were enrolled and randomized to receive DUV 25mg orally b.i.d or matching placebo for up to 14 days. The median age of the pts was 57 years. Baseline characteristics were well balanced between both arms (Table) other than pts in the DUV arm had shorter duration of symptoms at enrollment (7 vs. 9.5 days; p=0.003). All pts received remdesivir and dexamethasone as standard treatment. Median doses of study drug and days on treatment were 7 (5 vs. 7.5; p=0.142) and 4 (3 vs. 4.5; p=0.149), comparing DUV vs. placebo arms, respectively. One pt in the placebo arm died on Day 29. No significant difference was found in the primary composite endpoint of death or mechanical ventilation (12% vs. 13.64%; p=1.000) or ICU transfers (3 vs. 3). The PaO2/FiO2 ratio trended higher, and the chest X-ray severity score was lower in the DUV arm during the recovery phase (>Day 17). The SAE numbers (6 (0.24) vs 3 (0.14); p=0.373), median days of hospitalization (4 vs 5.5; p=0.909), oxygen use on day 15 (41.67% vs 40.91%; p=0.958) and day 29 (30.43% vs 28.57%; p=0.868) showed no significant differences in DUV vs. placebo arm (Table). Serum levels of IL-2 was significantly lower at early timepoints (Day 2-4) in subjects randomized to the DUV Arm. IL-2RA, IL-10, TNF-α, and MIP-1α/CCL3 were generally lower in DUV-treated subjects during the first two weeks. IL-6, IL-8, IP-10/CXCL10, and MCP-1/CCL2 levels were not significantly different between arms (Figure). Inflammatory biomarkers (Ferritin, CRP, d-dimer), anti-SARS Cov-2 IgG, and hematological parameters (CBC, CMP) were not significantly different between arms. Conclusions: The administration of short-course duvelisib to pts with severe COVID-19 was safe and did not impair serological response to SARS-CoV-2. While duvelisib reduced levels of IL-2, IL-2RA, and TNF-α, clinical outcomes for duvelisib-treated patients did not significantly improve compared to control subjects. The small sample size and sampling restricted to a short hospitalization may have limited the observed effects of duvelisib on other cytokines in the blood. These data suggest a regulatory role for the PI3K/AKT/mTOR pathway in T cell response to COVID-19 progression and the potential efficacy of duvelisib in treating pts with hyper-inflammatory conditions. Early initiation, and/or higher-dose, longer-term treatment might be necessary to achieve clinical therapeutic benefits. Further high-dimensional analysis on immunophenotyping of immune cells is needed to determine the effect of duvelisib in altering immune profile, mitigating T-cell exhaustion, and enhancing anti-viral adaptive immunity. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

The Dual PI3Kdg Inhibitor Duvelisib Potently Inhibits Cytokine Release Syndrome (CRS) While Maintaining CAR-T Function

The Dual PI3Kdg Inhibitor Duvelisib Potently Inhibits Cytokine Release Syndrome (CRS) While Maintaining CAR-T Function

9. The dual PI3K inhibitor duvelisib potently inhibits cytokine release syndrome while maintaining CAR-T function

9. The dual PI3K inhibitor duvelisib potently inhibits cytokine release syndrome while maintaining CAR-T function

Comparative kinase and cancer cell panel profiling of kinase inhibitors approved for clinical use from 2018 to 2020.

During the last two decades, kinase inhibitors have become the major drug class for targeted cancer therapy. Although the number of approved kinase inhibitors increases rapidly, comprehensive in vitro profiling and comparison of inhibitor activities is often lacking in the public domain. Here we report the extensive profiling and comparison of 21 kinase inhibitors approved by the FDA for oncology indications since June 2018 and 13 previously approved comparators on panels of 255 biochemical kinase assays and 134 cancer cell line viability assays. Comparison of the cellular inhibition profiles of the EGFR inhibitors gefitinib, dacomitinib, and osimertinib identified the uncommon EGFR p.G719S mutation as a common response marker for EGFR inhibitors. Additionally, the FGFR inhibitors erdafitinib, infigratinib, and pemigatinib potently inhibited the viability of cell lines which harbored oncogenic alterations in FGFR1-3, irrespective of the specific clinical indications of the FGFR inhibitors. These results underscore the utility of in vitro kinase inhibitor profiling in cells for identifying new potential stratification markers for patient selection. Furthermore, comparison of the in vitro inhibition profiles of the RET inhibitors pralsetinib and selpercatinib revealed they had very similar biochemical and cellular selectivity. As an exception, an NTRK3 fusion-positive cell line was potently inhibited by pralsetinib but not by selpercatinib, which could be explained by the targeting of TRK kinases in biochemical assays by pralsetinib but not selpercatinib. This illustrates that unexpected differences in cellular activities between inhibitors that act through the same primary target can be explained by subtle differences in biochemical targeting. Lastly, FLT3-mutant cell lines were responsive to both FLT3 inhibitors gilteritinib and midostaurin, and the PI3K inhibitor duvelisib. Biochemical profiling revealed that the FLT3 and PI3K inhibitors targeted distinct kinases, indicating that unique dependencies can be identified by combined biochemical and cellular profiling of kinase inhibitors. This study provides the first large scale kinase assay or cell panel profiling study for newly approved kinase inhibitors, and shows that comprehensive in vitro profiling of kinase inhibitors can provide rationales for therapy selection and indication expansion of approved kinase inhibitors.

Abstract 2661: Novel pharmacological approaches of inhibiting the PI3K/AKT/mTOR signaling pathway in T-cell lymphoma (TCL)

Abstract Introduction: T-cell lymphoma (TCL) accounts for 15% of all non-Hodgkin’s lymphoma cases with most patients developing relapsed/refractory (R/R) disease. The management of R/R TCL is challenging and responses to second and beyond-line therapy are generally poor. Pre-clinical and clinical studies have identified the relevance of PI3K/AKT/mTOR signaling pathway in TCL biology. The combination of PI3K inhibitor (PI3Ki) Duvelisib and the HDACi Romidepsin improved the overall response rate (ORR) of R/R TCL to 50-55% in a phase I/II study (Horwitz et. al. ASH 2018, Lugano 2021). Evaluation of PI3Ki and HDACi combinations in TCL pre-clinical models is needed to guide the design of future clinical trials. Methods: A panel of TCL cells lines were chosen representing T-cell acute lymphoblastic leukemia, T-lymphoblastic lymphoma, cutaneous T-cell lymphoma. A panel of PI3Ki (Omipalisib, Umbralisib and Duvelisib) and HDACi (Entinostat and Romidepsin) were selected to determine which combination would be most synergistic. Entinostat, an oral HDACi, was chosen for its remarkable preclinical and clinical activity in other lymphoma subtypes. Umbralisib is a new PI3Kδ inhibitor which was recently approved for treatment of follicular lymphoma and marginal zone lymphoma. Cells were exposed to Omipalisib (3.125-100nM), Umbralisib (1-320uM), or Duvelisib (1-100uM) alone or in combination with Entinostat (0.08-10uM) or Romidepsin (0.25-6) for 24, 48 and 72 hrs. Cell viability was measured using the CellTiter-Glo viability assay. Half-maximal inhibitory concentration (IC50) at 72hrs was determined for each drug and coefficient of synergy was calculated using Calcusyn Software. Changes in cellular metabolism and cell cycle distribution after exposure to PI3Ki were determined using DiOC6 staining and Propidium Iodide staining respectively. Epigenetic changes following exposure to Entinostat or Romidepsin were investigated for possible mechanisms. Results: In vitro exposure of TCL cell lines to PI3Ki or HDACi resulted in dose-dependent cell death. The IC50 at 72 hrs was 30-500nM for Omipalisib, 9-35uM for Umbralisib, 1-35uM for Duvelisib, 0.2-2uM for Entinostat and for 1-4nM Romidepsin. All HDACi and Pi3Ki combinations demonstrated additive and/or synergistic activity. Duvelisib combined with Entinostat or Romidepsin exhibited the most synergy. Methylation profiling demonstrated genomic wide hypomethylation, specifically DNMT3A, in Romidepsin treated samples compared to Entinostat. Conclusions: PI3Ki and HDACi combinations show significant synergy in TCL preclinical models. DNMT3A hypomethylation following Romidepsin exposure is being explored as the basis of PI3Ki and HDACi synergy. If confirmed in clinical trials, these results may refine the tolerability of the regimen for patients treated with this very promising PI3Ki/HDACi combination. Citation Format: Gabrielle Hartman, Cory Mavis, Juan J. Gu, Amber White, Taylor Mandeville, Pallawi Torka, Paola Ghione, Francisco J. Hernandez-Ilizaliturri. Novel pharmacological approaches of inhibiting the PI3K/AKT/mTOR signaling pathway in T-cell lymphoma (TCL) [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 2661.

Abstract 4195: Evaluation of the anti-myeloma effects of high and metronomic selinexor alone and in combination with duvelisib in vitro and in vivo

Abstract Introduction: Selinexor (Karyopharm Therapeutics) is an FDA-approved oral selective inhibitor of nuclear export (SINE) compound. It specifically blocks XPO1 enforcing the nuclear retention of tumor suppressor proteins restoring their anti-cancer functions. It also attenuates the phosphoinositide-3 kinase (PI3K)-AKT pathway by activating PTEN. Although activation of PI3K signaling is often detected in hematological malignancies, there are no data regarding the combination of selinexor with the PI3K inhibitor duvelisib for MM treatment. Thus, we evaluated the anti-myeloma effects of selinexor in combination with duvelisib in vitro and also studied alternative schedules of selinexor with dexamethasone in vivo using our MM xenograft models LAGκ-2. Methods: The human MM cell line U266 was obtained from ATCC. Primary MM tumor cells were isolated from MM patients’ bone marrow (BM) aspirates. Cell viability was quantified using the MTS cell proliferation assay. For the in vivo studies, the human myeloma xenograft LAGκ-2 was surgically implanted into SCID mice. Selinexor was administered via oral gavage at 2.5 mg/kg 5x per week, 5 mg/kg 4x per week on consecutive days, or 10 mg/kg 2x per week with one day between treatments. Dexamethasone was administered via intraperitoneal injection at 4 mg/kg 2x per week except the vehicle control. Results and Discussion: MTS assays showed selinexor induced concentration dependent inhibition of cell viability/proliferation in the MM cell line MM1s at 0.1, 0.4 and 1.6 μM. Selinexor alone at 0.2 μM reduced cell proliferation of primary MM tumor cells obtained from BM mononuclear cells (MCs) from a patient with progressive disease. We next examined cell viability in the presence of selinexor and duvelisib. MM1s or fresh BM mononuclear cells were incubated with a fixed concentration of selinexor (0.1μM) with increasing concentrations of duvelisib (1.5 μM -25 μM) for 48 h. The results showed that duvelisib enhanced the cytotoxic effects of selinexor in a concentration dependent manner. We also evaluated dosing and scheduling of selinexor and dexamethasone in vivo using SCID mice bearing LAGκ-2 MM xenografts. When selinexor was combined with dexamethasone, lower more frequent dosing showed greater inhibition of tumor growth than mid-range and higher less frequent dosing of this SINE. This study illustrates that the combination of selinexor and duvelisib showed enhanced cytotoxic effects in vitro compared with single agent treatment, and we will further evaluate the anti-MM effects of selinexor in combination with duvelisib in vivo using our human MM xenograft models. These studies suggest that the combination of a SINE and PI3K inhibitor may be effective for MM treatment. Citation Format: Haiming Chen, Stacy Behare, Mingjie Li, Marissa Goldwater, Ava Hekmati, Jasmin Cao, Rocky Levin, Ning Xu, James Berenson. Evaluation of the anti-myeloma effects of high and metronomic selinexor alone and in combination with duvelisib in vitro and in vivo [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 4195.

PI3K Inhibitors for the Treatment of Chronic Lymphocytic Leukemia: Current Status and Future Perspectives.

Simple SummaryThe development of small agents targeting the B-cell receptor (BCR) pathway revolutionized the treatment of chronic lymphocytic leukemia (CLL). BCR-dependent leukemic cell proliferation is governed by phosphoinositide 3-kinase (PI3K) signaling. The selective PI3Kδ inhibitor idelalisib and dual PI3Kδ/γ inhibitor duvelisib are currently approved by the Food and Drug Administration and European Medicine Agency (only idelalisib) for CLL treatment. Umbralisib, a selective PI3Kδ and casein kinase-1ε (CK1ε) inhibitor, has a different chemical structure and a more favorable safety profile than other PI3K inhibitors (PiK3is); this has enabled its use in combination regimens in clinical trials in first-line and relapsed/refractory CLL. This paper summarizes the development of PI3Kis, their current role and future perspectives in the treatment of patients with CLL.Phosphoinositide 3-kinases (PI3Ks) signaling regulates key cellular processes, such as growth, survival and apoptosis. Among the three classes of PI3K, class I is the most important for the development, differentiation and activation of B and T cells. Four isoforms are distinguished within class I (PI3Kα, PI3Kβ, PI3Kδ and PI3Kγ). PI3Kδ expression is limited mainly to the B cells and their precursors, and blocking PI3K has been found to promote apoptosis of chronic lymphocytic leukemia (CLL) cells. Idelalisib, a selective PI3Kδ inhibitor, was the first-in-class PI3Ki introduced into CLL treatment. It showed efficacy in patients with del(17p)/TP53 mutation, unmutated IGHV status and refractory/relapsed disease. However, its side effects, such as autoimmune-mediated pneumonitis and colitis, infections and skin changes, limited its widespread use. The dual PI3Kδ/γ inhibitor duvelisib is approved for use in CLL patients but with similar toxicities to idelalisib. Umbralisib, a highly selective inhibitor of PI3Kδ and casein kinase-1ε (CK1ε), was found to be efficient and safe in monotherapy and in combination regimens in phase 3 trials in patients with CLL. Novel PI3Kis are under evaluation in early phase clinical trials. In this paper we present the mechanism of action, efficacy and toxicities of PI3Ki approved in the treatment of CLL and developed in clinical trials.

Dual PI3Kδ/γ Inhibitor Duvelisib Prevents Development of Neuropathic Pain in Model of Paclitaxel-Induced Peripheral Neuropathy.

The development of painful paclitaxel-induced peripheral neuropathy (PIPN) represents a major dose-limiting side effect of paclitaxel chemotherapy. Here we report a promising effect of duvelisib (Copiktra), a novel FDA-approved PI3Kδ/γ isoform-specific inhibitor, in preventing paclitaxel-induced pain-like behavior and pronociceptive signaling in DRGs and spinal cord dorsal horn (SCDH) in rat and mouse model of PIPN. Duvelisib blocked the development of mechanical hyperalgesia in both males and females. Moreover, duvelisib prevented paclitaxel-induced sensitization of TRPV1 receptors, and increased PI3K/Akt signaling in small-diameter DRG neurons and an increase of CD68+ cells within DRGs. Specific optogenetic stimulation of inhibitory neurons combined with patch-clamp recording revealed that duvelisib inhibited paclitaxel-induced weakening of inhibitory, mainly glycinergic control on SCDH excitatory neurons. Enhanced excitatory and reduced inhibitory neurotransmission in the SCDH following PIPN was also alleviated by duvelisib application. In summary, duvelisib showed a promising ability to prevent neuropathic pain in PIPN. The potential use of our findings in human medicine may be augmented by the fact that duvelisib is an FDA-approved drug with known side effects.SIGNIFICANCE STATEMENT We show that duvelisib, a novel FDA-approved PI3Kδ/γ isoform-specific inhibitor, prevents the development of paclitaxel-induced pain-like behavior in males and females and prevents pronociceptive signaling in DRGs and spinal cord dorsal horn in rat and mouse model of paclitaxel-induced peripheral neuropathy.

Evidence of a Synergistic Cross-Talk between the B Cell Receptor (BCR) and Nicotinamide Phosphoribosyl Transferase (NAMPT) in Richter's Syndrome Patient-Derived Xenograft Models: Therapeutic Implications

Background: A rare complication of Chronic Lymphocytic Leukemia (CLL), Richter's Syndrome (RS) represents the transformation of a pre-existing CLL into a Diffuse Large B-cell Lymphoma (DLBCL), generally associated with poor prognosis. Current therapeutic approaches are limited and do not significantly reduce disease progression. For these reasons there is intense investigation to identify potentially druggable molecular circuits, opening the way to innovative combination therapies.Among the several oncogenic signalling pathways that may contribute to disease progression, the B Cell Receptor (BCR) is a main driver and an actionable target. We previously showed that BCR ligation in CLL cells increases expression of nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme in the salvage NAD pathway starting from nicotinamide, a finding in line with the notion of oncogenic-driven metabolic reprogramming. In this context, increased NAMPT expression leading to heightened NAD+ levels could sustain proliferation through the modulation of the activity of several intracellular enzymes, including sirtuins (NAD-dependent deacetylases).Aim: This work explores the connections between BCR signalling and the NAMPT/NAD/sirtuin axis in RS cells, asking the question of whether BCR and NAMPT can be simultaneously targeted.Methods: RS-PDX cells were freshly purified from tumor masses grown in mice and immediately used for short ex-vivo experiments. For in vivo experiments, NSG mice were injected subcutaneously with RS-PDX cells, which were left to engraft until a palpable mass was evident. Mice were then randomized to receive duvelisib, OT82 or a combination of the two for two consecutive weeks. Control mice were similarly treated with vehicle only. Mice were under a niacin-free diet.Results: By using our 4 RS patient-derived xenografts (PDX) models, we invariably observed high levels of NAMPT expression. High levels of NAMPT expression were also observed in 15 primary RS lymph node biopsies analyzed by RNA sequencing. BCR engagement through αIgM polyclonal antibodies significantly up-regulated NAMPT expression, as determined by qRT-PCR and protein analysis, with a concomitant increase in intracellular NAD+ levels. We then asked whether RS cells are sensitive to NAMPT inhibition, alone or in combination with drugs that target the BCR pathway. As most RS patients would likely have been treated during the preceding CLL phase with a BTK inhibitor, possibly developing resistance, we turned to PI3K inhibitors, which are less commonly used for CLL therapy. As NAMPT inhibitors (NAMPTi) we used both FK866 and OT-82, which are validated small molecules. Results indicated that the combination of the dual PI3K-δ/γ inhibitor duvelisib, with either FK866 or OT-82 induces dramatic apoptosis in all 4 models tested, as confirmed by annexinV/PI staining, by caspase 3 activation and by a significant drop in ATP and NAD+ levels. Importantly, two RS-PDX models (RS9737 and RS1316) were fully resistant to NAMPTi used alone, likely due to high levels of nicotinate phosphoribosyltransferase (NAPRT), which is the rate-limiting enzyme in the NAD salvage pathway that starts from nicotinic acid. However, addition of duvelisib, which was mildly effective when used alone, was followed by marked apoptosis even in these two models.Molecular dissection of the pathway showed that the combination of duvelisib and NAMPTi was followed by complete inhibition of the PI3K pathway, which was only partially blocked by duvelisib alone, even at high doses. The connection between NAMPT and PI3K is represented by cytoplasmic sirtuins, particularly SIRT2, which activate AKT through de-acetylation. Immunoprecipitation and two-dimensional gel electrophoresis showed that in the presence of NAMPTi, the amount of acetylated, i.e., inactive, AKT increased considerably. Consistently, treatment of RS-PDX mice with a combination of duvelisib and OT-82 was followed by significantly higher responses and longer animal survival.Conclusions: These results highlight a crosstalk between BCR signalling and NAMPT/sirtuin axis in RS models, showing the increased efficacy of the dual targeting (i.e., PI3K-δ/γ and NAMPT), and supporting this novel and promising therapeutic strategy for the treatment of RS patients. DisclosuresDeaglio: Heidelberg Pharma: Research Funding; Astra Zeneca: Research Funding.

PI3K δ /γ Inhibition Enhances the Expansion and Anti-Tumor Cytotoxicity of CART Cells for CLL Patients

Background:While CD19-targeted chimeric antigen receptor (CAR) based T cell therapy has shown promise in the treatment of chronic lymphocytic leukemia (CLL), overall efficacy is limited due to impaired T-cell fitness. We have previously shown that dual inhibition of PI3Kδ and PI3Kγ enhanced mitochondrial mass and ex vivo expansion of central and stem cell memory T cells from CLL patients(Funk, 2019,Journal for Immunotherapy of Cancer). In this study, we hypothesized that pharmacological inhibition of these pathways during ex vivo culture would increase the expansion and in vivo anti-tumor cytotoxicity.Methods: Peripheral blood mononuclear cells (PBMCs) were isolated from the blood of CLL patients by ficol hypaque centrifugation. T cells were negatively selected using MACS beads and transduced with CD19 CAR lentivirus (encoding CD28 or 41BB co-stimulatory domains) and stimulated with anti-CD3/CD28 beads in media containing 30 U/mL interleukin-2 with or without the PI3Kδ/γ inhibitor duvelisib (Duv) for 15 days. NOG mice were engrafted with the OSU-CLL cell line for 14 to 18 days with tumor burden measured by flow cytometry of blood samples from the mice, comprising a mean 0.15% of peripheral nucleated cell content. Control-CART or Duv-CART were injected by tail vein injection. Frequencies of CART, OSU-CLL cells and immune checkpoint molecule expression of CART or T cells in blood were measured by serial flow cytometry. Kaplan-Meier survival plots were represented as recipient survival on the indicated daysResults: Treatment with either CD28 or 4-1BB Duv-CART cells led to significantly prolonged survival relative to control-CART (Figure 1, P<0.05). Recipients of Duv-CART cleared circulating OSU-CLL faster than control CART (Figure 2. P<0.05 at day26 for CD28 CART) and exhibited greater peak expansion and persistence of total CART and CD8+ CART. Recipients of Duv-CART cells had significantly greater in vivo persistence and expansion of total CART and CD8+ CART (Figure 3, P<0.001, day14 after CART were infused). Consistent with improved survival, both CD28 Duv-CART and 4-BB Duv-CART show reduced expression of LAG3, TIM3 and PD1 in the CD4 (Figure 4) and CD8+ subsets at earlier time point in vivo. (* p<0.05, **p≤0.01, ***p≤0.001, ****p≤0.0001).Conclusions: Inhibition of PI3Kd/g during CART cell culture decreased the expression of immune checkpoint molecules and enhanced in vivo expansion leading to greater efficacy in eliminating CLL. [Display omitted] DisclosuresWaller: Verastem Oncology: Consultancy, Research Funding; Cambium Oncology: Current holder of individual stocks in a privately-held company, Current holder of stock options in a privately-held company.