Response-adapted, time-limited venetoclax, umbralisib, and ublituximab for relapsed/refractory chronic lymphocytic leukemia

ABSTRACT

Many patients with chronic lymphocytic leukemia (CLL) will develop treatment resistance to Bruton tyrosine kinase (BTK) inhibitors. Phosphatidylinositol-3-kinase (PI3K) inhibitors, including umbralisib, have significant clinical activity in relapsed/refractory CLL, but prolonged exposure is associated with potential toxicities. Owing to the synergistic antitumor effects of combined PI3K and BCL-2 inhibition, we sought to explore the feasibility of response-adapted, time-limited therapy to optimize disease control while mitigating the risks of prolonged treatment. We conducted a phase 1/2 clinical trial to determine the safety and efficacy of venetoclax in combination with umbralisib and the anti-CD20 monoclonal antibody, ublituximab, (U2-VeN) in patients with relapsed/refractory CLL (N = 46) and Richter transformation (N = 5). After 12 cycles, treatment was stopped for patients with CLL who achieved undetectable minimal residual disease (uMRD). Adverse events of special interest included diarrhea in 50% of patients (11% grade 3/4), and aspartate aminotransferase and/or alanine aminotransferase elevation in 15 patients (33%), with 3 (7%) grade 3/4. There were no cases of tumor lysis syndrome related to venetoclax, with outpatient initiation in 96% of patients. The intent-to-treat overall response rate for CLL was 98% with best response of 100% in evaluable patients (42% complete responses). The end-of-treatment rate of uMRD at 10-4 in bone marrow was 77% (30/39), including a 71% uMRD rate among 14 patients refractory to prior BTK inhibitor. Time-limited venetoclax and U2 is safe and highly effective combination therapy for patients with relapsed/refractory CLL including those who have been previously treated with covalent BTK inhibitors. This trial was registered on www.clinicaltrials.gov as #NCT03379051.

G protein-coupled receptor 183 mediates the sensitization of Burkitt lymphoma tumors to CD47 immune checkpoint blockade by anti-CD20/PI3Kδi dual therapy

Background

Immunotherapy-based regimens have considerably improved the survival rate of B-cell non-Hodgkin lymphoma (B-NHL) patients in the last decades; however, most disease subtypes remain almost incurable. TG-1801, a bispecific antibody that targets CD47 selectively on CD19+ B-cells, is under clinical evaluation in relapsed/refractory (R/R) B-NHL patients either as a single-agent or in combination with ublituximab, a new generation CD20 antibody.

Methods

A set of eight B-NHL cell lines and primary samples were cultured in vitro in the presence of bone marrow-derived stromal cells, M2-polarized primary macrophages, and primary circulating PBMCs as a source of effector cells. Cell response to TG-1801 alone or combined with the U2 regimen associating ublituximab to the PI3Kδ inhibitor umbralisib, was analyzed by proliferation assay, western blot, transcriptomic analysis (qPCR array and RNA sequencing followed by gene set enrichment analysis) and/or quantification of antibody-dependent cell death (ADCC) and antibody-dependent cell phagocytosis (ADCP). CRISPR-Cas9 gene edition was used to selectively abrogate GPR183 gene expression in B-NHL cells. In vivo, drug efficacy was determined in immunodeficient (NSG mice) or immune-competent (chicken embryo chorioallantoic membrane (CAM)) B-NHL xenograft models.

Results

Using a panel of B-NHL co-cultures, we show that TG-1801, by disrupting the CD47-SIRPα axis, potentiates anti-CD20-mediated ADCC and ADCP. This led to a remarkable and durable antitumor effect of the triplet therapy composed by TG-1801 and U2 regimen, in vitro, as well as in mice and CAM xenograft models of B-NHL. Transcriptomic analysis also uncovered the upregulation of the G protein-coupled and inflammatory receptor, GPR183, as a crucial event associated with the efficacy of the triplet combination. Genetic depletion and pharmacological inhibition of GPR183 impaired ADCP initiation, cytoskeleton remodeling and cell migration in 2D and 3D spheroid B-NHL co-cultures, and disrupted macrophage-mediated control of tumor growth in B-NHL CAM xenografts.

Conclusions

Altogether, our results support a crucial role for GPR183 in the recognition and elimination of malignant B cells upon concomitant targeting of CD20, CD47 and PI3Kδ, and warrant further clinical evaluation of this triplet regimen in B-NHL.

Adding Umbralisib and Ublituximab (U2) to Ibrutinib in Patients with CLL: A Phase II Study of an MRD-Driven Approach

PURPOSE

Ibrutinib has transformed the management of chronic lymphocytic leukemia (CLL), though its use is limited by toxicity and resistance. In this study, we utilized an "add on" approach for patients who had been treated with ibrutinib in the front-line or relapsed/refractory settings with detectable MRD. Umbralisib and ublituximab (U2) were added on to ibrutinib, patients were treated until achieving undetectable-MRD (U-MRD), and then they entered a period of treatment-free observation (TFO).

PATIENTS AND METHODS

Patients were eligible if they received ibrutinib in any line of therapy for at least 6 months and had detectable MRD (flow cytometry, <1 cell in 10-4 cutoff for U-MRD). U2 was added to ibrutinib, and patients were monitored serially for MRD. Once U-MRD was achieved or a total of 24 cycles were administered, patients entered a period of TFO. The primary study objective was rate of U-MRD. Secondary endpoints included safety and durability of clinical benefit after treatment discontinuation.

RESULTS

Twenty-eight patients were enrolled of whom 27 were evaluable for efficacy. Patients received ibrutinib for a median of 21 months (range 7-67) prior to study enrollment. Fourteen patients (52%) have achieved U-MRD per protocol whereas 78% had at least one U-MRD evaluation. Seventeen patients (63%) have entered TFO after a median of 6.4 months on triplet therapy. Progression-free survival at 12 months was estimated at 95%. Grade ≥3 adverse events were hypertension 7%, diarrhea 4%, and increased ALT/AST 4%.

CONCLUSIONS

This triplet approach utilizes the addition of U2 to ibrutinib as an MRD-driven time-limited therapy. This therapy was well tolerated and effective. TFO following this therapy appears durable in ongoing follow-up.

Ublituximab versus Teriflunomide in Relapsing Multiple Sclerosis

BACKGROUND

The monoclonal antibody ublituximab enhances antibody-dependent cellular cytolysis and produces B-cell depletion. Ublituximab is being evaluated for the treatment of relapsing multiple sclerosis.

METHODS

In two identical, phase 3, double-blind, double-dummy trials (ULTIMATE I and II), participants with relapsing multiple sclerosis were randomly assigned in a 1:1 ratio to receive intravenous ublituximab (150 mg on day 1, followed by 450 mg on day 15 and at weeks 24, 48, and 72) and oral placebo or oral teriflunomide (14 mg once daily) and intravenous placebo. The primary end point was the annualized relapse rate. Secondary end points included the number of gadolinium-enhancing lesions on magnetic resonance imaging (MRI) by 96 weeks and worsening of disability.

RESULTS

A total of 549 participants were enrolled in the ULTIMATE I trial, and 545 were enrolled in the ULTIMATE II trial; the median follow-up was 95 weeks. In the ULTIMATE I trial, the annualized relapse rate was 0.08 with ublituximab and 0.19 with teriflunomide (rate ratio, 0.41; 95% confidence interval [CI], 0.27 to 0.62; P<0.001); in the ULTIMATE II trial, the annualized relapse rate was 0.09 and 0.18, respectively (rate ratio, 0.51; 95% CI, 0.33 to 0.78; P = 0.002). The mean number of gadolinium-enhancing lesions was 0.02 in the ublituximab group and 0.49 in the teriflunomide group (rate ratio, 0.03; 95% CI, 0.02 to 0.06; P<0.001) in the ULTIMATE I trial and 0.01 and 0.25, respectively (rate ratio, 0.04; 95% CI, 0.02 to 0.06; P<0.001), in the ULTIMATE II trial. In the pooled analysis of the two trials, 5.2% of the participants in the ublituximab group and 5.9% in the teriflunomide group had worsening of disability at 12 weeks (hazard ratio, 0.84; 95% CI, 0.50 to 1.41; P = 0.51). Infusion-related reactions occurred in 47.7% of the participants in the ublituximab group. Serious infections occurred in 5.0% in the ublituximab group and in 2.9% in the teriflunomide group.

CONCLUSIONS

Among participants with relapsing multiple sclerosis, ublituximab resulted in lower annualized relapse rates and fewer brain lesions on MRI than teriflunomide over a period of 96 weeks but did not result in a significantly lower risk of worsening of disability. Ublituximab was associated with infusion-related reactions. (Funded by TG Therapeutics; ULTIMATE I and II ClinicalTrials.gov numbers, NCT03277261 and NCT03277248.).

Updated results of the selective Bruton tyrosine kinase (BTK) inhibitor TG-1701, as monotherapy and in combination with ublituximab and umbralisib (U2) in patients (pts) with B-cell malignancies

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Background: TG-1701 is a selective, covalent BTK inhibitor administered once daily (QD). Both the “U2” combination (anti-CD20 mAb ublituximab + the PI3Kδ-CK1ε inhibitor umbralisib) and BTK inhibition are highly active in treatment-naïve (TN) and relapsed/refractory (R/R) CLL, each having previously demonstrated superiority over standard chemoimmunotherapy. Here we report the results of the dose escalation of TG-1701 monotherapy and TG-1701+U2. Methods: Pts with R/R CLL and lymphoma were enrolled in a Ph 1 study initially evaluating dose escalation (DE) of oral TG-1701 QD continuously administered in 28-day cycles (100, 200, 300, and 400 mg). After characterizing the safety profile of TG-1701 monotherapy, we implemented a parallel DE arm of TG-1701+U2. Select dose levels of TG-1701 monotherapy were expanded in CLL, MCL and Waldenström's (WM). All pts were treated until disease progression. The primary objectives are to characterize the safety profile and define the recommended Ph 2 doses for the drugs alone and in combination. Results: As of 03 February 2021, 123 pts were treated with TG-1701: 25 in the monotherapy DE arm, 61 in the 200 mg disease-specific cohorts (20 CLL [5 TN], 21 MCL [4 TN], 20 WM [8 TN]), 20 in the 300 mg CLL cohort (4 TN), and 17 in the 1701+U2 DE arm. The median # of prior therapies was 1 (range, 1 - 10). All pts were BTKi-naïve. All 123 pts were evaluable for safety. TG-1701 was well tolerated and the maximum tolerated dose (MTD) for monotherapy was not reached at 400 mg (demonstrating near 100% saturation of the BTK at all dose levels studied). Treatment emergent adverse events (TEAE) of clinical interest included atrial fibrillation (AF 4.0% of pts, G ≥3 in 1 case), G ≥3 hypertension (2.4%), and bleeding events (18.7%, all G1-2). No cases of ventricular tachyarrhythmia were reported. TEAEs leading to TG-1701 dose reduction occurred in 6.5% of pts. TEAEs leading to treatment discontinuation occurred in 1.6% of pts (AF, COVID-19). At the data cut-off, 119 pts were evaluable for response, including 40 in DE (Table). The median duration of response has not been reached among responders overall. The median follow-up (mFU range) was 15.9 mos (1.3 - 28.6+) in DE and 8.5 mos (1.4 -15.6+) in disease-specific cohorts. Conclusions: TG-1701 exhibits an encouraging safety and efficacy profile. The combination of 1701+U2 has been well tolerated and dose escalation continues. The combination shows enhanced depth of response over TG-1701 monotherapy. Recruitment to this study continues. Response per investigator review by treatment group. Clinical trial information: NCT03671590. [Table: see text]

Umbralisib, a Dual PI3Kδ/CK1ε Inhibitor in Patients With Relapsed or Refractory Indolent Lymphoma

PURPOSE

Phosphatidylinositol-3-kinase (PI3K) inhibitors have shown activity in relapsed or refractory (R/R) indolent non-Hodgkin lymphoma (iNHL). PI3K inhibitors have been hampered by poor long-term tolerability and toxicity, which interfere with continuous use. Umbralisib, a dual inhibitor of PI3Kδ/casein kinase-1ε, exhibits improved selectivity for PI3Kδ compared with other PI3K inhibitors. This phase IIb trial was designed to evaluate the efficacy and safety of umbralisib in patients with R/R iNHL.

PATIENTS AND METHODS

In this multicohort, open-label, phase IIb study, 208 patients with R/R marginal zone, follicular, or small lymphocytic lymphoma (MZL, FL, or SLL) unresponsive to prior treatments (≥ 1 MZL; ≥ 2 FL/SLL), including ≥ 1 anti-CD20-based therapy, were administered umbralisib 800 mg orally once daily until disease progression, unacceptable toxicity, or study withdrawal. Primary end point is overall response rate; secondary end points include time to response, duration of response, progression-free survival, and safety.

RESULTS

The median follow-up is 27.7 months (efficacy) and 21.4 months (safety). The overall response rate was 47.1%, and tumor reduction occurred in 86.4% of patients. The median time to response was 2.7-4.6 months. The median duration of response was not reached for MZL, 11.1 months for FL, and 18.3 months for SLL. Median progression-free survival was not reached for MZL, 10.6 months for FL, and 20.9 months for SLL. At least one grade ≥ 3 treatment-emergent adverse event (TEAE) was reported in 53.4% of patients. TEAEs led to umbralisib discontinuation in 32 patients (15.4%). A total of 31 patients (14.9%) discontinued because of a treatment-related adverse event. Grade ≥ 3 TEAEs reported in ≥ 10% of patients: neutropenia (11.5%) and diarrhea (10.1%). Increased ALT/AST (grade ≥ 3) occurred in 6.7%/7.2% of patients.

CONCLUSION

Umbralisib achieved meaningful clinical activity in heavily pretreated patients with iNHL. The safety profile was manageable, with a relatively low incidence of immune-mediated toxicities and adverse event-related discontinuations.

Ublituximab plus ibrutinib versus ibrutinib alone for patients with relapsed or refractory high-risk chronic lymphocytic leukaemia (GENUINE): a phase 3, multicentre, open-label, randomised trial

BACKGROUND

Patients with chronic lymphocytic leukaemia and high-risk features have poorer outcomes on ibrutinib than those without high-risk features. The aim of this study was to assess the benefit of adding ublituximab, an anti-CD20 monoclonal antibody, to ibrutinib therapy in this population.

METHODS

We did a randomised, phase 3, multicentre study (GENUINE) of patients aged 18 years or older with relapsed or refractory chronic lymphocytic leukaemia with at least one of 17p deletion, 11q deletion, or TP53 mutation, at 119 clinics in the USA and Israel. Eligible patients had received at least one previous chronic lymphocytic leukaemia therapy and had an Eastern Cooperative Oncology Group performance status of 2 or lower. We randomised patients (1:1) using permuted block randomisation with a block size of four and stratified by previous lines of therapy (one vs two or more) to receive ibrutinib alone or ibrutinib in combination with ublituximab. Treatment allocation was not masked to patients or investigators. Ibrutinib was given orally daily at 420 mg for all cycles. Ublituximab was given intravenously in 28-day cycles, with increasing doses during cycle 1 (≤150 mg on day 1, 750 mg on day 2, and 900 mg on days 8 and 15) and continuing at 900 mg on day 1 of cycles 2-6. After cycle 6, ublituximab was given at 900 mg every three cycles. The study was initially designed with co-primary endpoints of progression-free survival and overall response rate but due to protracted patient accrual, the protocol was amended to have a single primary endpoint of independent review committee-assessed overall response rate (defined as the proportion of patients who had a partial response, complete response, or complete response with incomplete marrow recovery according to the 2008 International Workshop on CLL criteria) in the intention-to-treat population. Safety was evaluated in the population of patients who received at least one dose of study treatment. This trial is registered with ClinicalTrials.gov, NCT02301156, and the final analysis is presented.

FINDINGS

224 patients were assessed for eligibility, of whom 126 patients were enrolled and randomly assigned to receive ublituximab plus ibrutinib (n=64) or ibrutinib alone (n=62) between Feb 6, 2015, and Dec 19, 2016. After a median follow-up of 41·6 months (IQR 36·7-47·3), the overall response rate was 53 (83%) of 64 patients in the ublituximab plus ibrutinib group and 40 (65%) of 62 patients in the ibrutinib group (p=0·020). 117 patients, including 59 in the ublituximab plus ibrutinib group and 58 in the ibrutinib group, received at least one dose of treatment and were included in safety analyses. Most adverse events were grade 1 or 2. The most common grade 3 and 4 adverse events were neutropenia (11 [19%] patients in the ublituximab plus ibrutinib group and seven [12%] in the ibrutinib group), anaemia (five [8%] and five [9%]), and diarrhoea (six [10%] and three [5%]). The most common serious adverse events were pneumonia (six [10%] in the ublituximab plus ibrutinib group and four [7%] in the ibrutinib group), atrial fibrillation (four [7%] and one [2%]), sepsis (four [7%] and one [2%]), and febrile neutropenia (three [5%] and one [2%]). Two patients in the ublituximab plus ibrutinib group died due to adverse events (one cardiac arrest and one failure to thrive), neither of which were treatment-related. Five patients in the ibrutinib group died due to adverse events, including one cardiac arrest, one cerebral infarction, one intracranial haemorrhage, one Pneumocystis jirovecii pneumonia infection, and one unexplained death; the death due to cardiac arrest was considered to be treatment-related.

INTERPRETATION

The addition of ublituximab to ibrutinib resulted in a statistically higher overall response rate without affecting the safety profile of ibrutinib monotherapy in patients with relapsed or refractory high-risk chronic lymphocytic leukaemia. These findings provide support for the addition of ublituximab to Bruton tyrosine kinase inhibitors for the treatment of these patients.

FUNDING

TG Therapeutics.

Effect of adding ublituximab to ibrutinib on PFS, ORR, and MRD negativity in previously treated high-risk chronic lymphocytic leukemia: Final results of the GENUINE phase III study

8022

Background: The BTK inhibitor ibrutinib (IB) has advanced the treatment for patients (pts) with CLL, however, among pts with high-risk CLL, disease control with IB is less durable. Ublituximab (UTX) is a glycoengineered mAb with enhanced ADCC. The GENUINE study evaluated the addition of UTX to IB vs. IB alone in high-risk rel/ref CLL. With a median follow up now 3.5+ yrs, we present the final results. Methods: Eligible pts having rel/ref CLL with centrally confirmed del17p, del11q, and/or a TP53 mutation, were randomized 1:1 to IB (420 mg QD) alone or with UTX (900 mg on D1, 8, 15 of Cy 1, D1 of Cy 2-6, and Q3 Cy thereafter). No limit on # of prior Tx; prior IB excluded. Primary endpoint was overall response rate (ORR) by iwCLL 2008 (excludes PR-L); secondary endpoints were CR rate, peripheral blood MRD negativity (analyzed centrally), PFS, and safety. Response was by blinded independent review. Results: 117 pts were treated (59 in UTX + IB arm; 58 in IB arm). Med age was 66 yrs and med # of prior Tx was 1 (range 1-5) for each arm. Baseline features were relatively balanced including ECOG, gender, and med time since diagnosis (6+ yrs). 17p del was greater in the IB arm (50% vs 44%); bulky disease was greater in UTX + IB arm (47% vs 28%); IGHV-unmut was 83% for both arms. At data-cutoff of Sep 1, 2019, AEs were comparable between the arms, except infusion reactions (UTX + IB: All G 53% / G 3/4 3%) and neutropenia (All G 36% vs 21%, G 3/4 19% vs. 12%) which were higher for UTX + IB. At a med follow up of 42 mos, all efficacy endpoints were in favor of UTX + IB (see Table). Conclusions: In contrast to prior studies adding rituximab to IB, GENUINE is the first randomized trial to demonstrate a PFS benefit with the addition of an anti-CD20 to IB. Increasing depth of response (CR rate, MRD-neg) post first year of Tx supports maintenance therapy with UTX. Clinical trial information: NCT02301156 . [Table: see text]

Abstract CT132: Umbralisib monotherapy demonstrates efficacy and safety in patients with relapsed/refractory marginal zone lymphoma: A multicenter, open-label, registration directed Phase II study

Background: Rituximab (RTX) alone or in combination with chemotherapy has substantially improved treatment outcomes for patients (pts) with marginal zone lymphoma (MZL), but relapse is common and not all pts are acceptable candidates for, or respond to, current salvage therapies. Umbralisib is a novel, next-generation PI3K-delta inhibitor with unique inhibition of casein kinase-1ϵ (CK1ϵ) and, compared to earlier generation PI3K-delta inhibitors, exhibits a differentiated tolerability profile with reduced rates of immune-mediated toxicity (Burris et al, 2018). This registration-directed study evaluates the efficacy and safety of umbralisib in pts with relapsed/refractory (R/R) MZL.

Methods: Pts had histologically confirmed MZL, ECOG PS ≤2, and had previously received ≥1 prior therapy including at least one CD20 monoclonal antibody (mAb)-containing regimen. All pts received umbralisib 800 mg orally once daily until progression or unacceptable toxicity. The primary study endpoint was overall response rate (ORR) as assessed by an independent review committee (IRC) according to 2007 IWG criteria. ORR by investigator assessment is reported here, and ORR by IRC is forthcoming. Secondary endpoints included duration of response (DOR), progression-free survival (PFS), and safety.

Results: Sixty-nine pts were enrolled; we report on the first 38 who are eligible for at least 6 months (mos) of follow-up as of the data cutoff date. Disease status for the 38 pts: extranodal (n=23), nodal (n=8), and splenic (n=7). Median age was 67 years (range, 34-81). Median number of prior systemic therapies was 2 (range, 1-5). Seven pts (18%) had received monotherapy RTX only, and 26 (68%) had received at least one CD20 mAb-containing chemoimmunotherapy. As of the cut-off date, the median follow-up was 9.6 mos. Per investigator assessment, ORR was 55% (4 CRs and 17 PRs), 29% of pts (n=11) had stable disease (SD) of which 6 of these SD pts remain on study with durations ranging from 7-12+ mos. The clinical benefit rate (CR+PR+SD) was 84%, and 91% of pts with at least 1 post-baseline assessment experienced tumor reductions. The median time to initial response was 2.7 mos, while the median DOR was not reached (95% CI: 8.4-not reached). The 12-month PFS was 71%. The most common (≥20%) adverse events (AE) of any grade included: diarrhea (45%), nausea (29%), fatigue (26%), headache (26%), cough (24%), and decreased appetite (21%). The most common Grade 3/4 events were neutropenia (8%), febrile neutropenia (5%), and diarrhea (5%). As of the cutoff date, 16 pts discontinued treatment (PD: 18%; AEs: 8%; pt decision: 8%; physician decision: 8%) and 58% continue treatment.

Conclusions: PI3K-delta inhibition with single-agent umbralisib is active and well tolerated in pts with R/R MZL, achieving durable responses with chemotherapy-free therapy.

Citation Format: Nathan H. Fowler, Felipe Samaniego, Wojciech Jurczak, Ewa Lech-Maranda, Nilanjan Ghosh, Bertrand Anz, Piers Patten, James A. Reeves, Lori A. Leslie, Piotr Smolewski, Julio C. Chavez, Paolo Ghia, Corrado Tarella, John M. Burke, Jeff Sharman, Kathryn Kolibaba, Owen A. O'Connor, Chan Y. Cheah, Hari P. Miskin, Peter Sportelli, Michael S. Weiss, Pier Luigi Zinzani. Umbralisib monotherapy demonstrates efficacy and safety in patients with relapsed/refractory marginal zone lymphoma: A multicenter, open-label, registration directed Phase II study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT132.

Umbralisib monotherapy demonstrates efficacy and safety in patients with relapsed/refractory marginal zone lymphoma: A multicenter, open label, registration directed phase II study

7506

Background: Rituximab (RTX) alone or with chemo has substantially improved outcomes for patients (pts) with marginal zone lymphoma (MZL), but relapse is common and not all pts are candidates for or respond to current salvage therapies. Umbralisib is a novel, next-gen PI3Kδ inhibitor with unique inhibition of casein kinase-1ε (CK1ε) and a differentiated tolerability profile compared to earlier PI3Kδ inhibitors (Burris et al, 2018). This registration-directed study evaluates the efficacy and safety of umbralisib in pts with rel/ref (R/R) MZL. Methods: Pts had histologically confirmed MZL, ECOG PS ≤2, and ≥1 prior therapy including ≥1 anti-CD20 mAb-containing regimen. Pts received umbralisib 800 mg orally once daily until PD or unacceptable toxicity. The primary endpoint was overall response (ORR) as assessed by independent review (IRC) per 2007 IWG criteria. ORR by investigator assessment is reported here, and ORR by IRC is forthcoming. Secondary endpoints included duration of response (DOR), PFS, and safety. Results: 69 pts were enrolled; we report on the first 38 who are eligible for at least 6 months (mos) of follow-up as of the data cutoff. Among the 38 pts: extranodal (n = 23), nodal (n = 8), and splenic (n = 7). Median age was 67 years (range, 34-81). Median # of prior systemic therapies was 2 (range, 1-5). Seven pts (18%) had monotherapy RTX only, and 26 (68%) had at least one anti-CD20 mAb-containing chemoimmunotherapy. Median follow-up was 9.6 mos. ORR was 55% (4 CRs and 17 PRs). Eleven pts (29%) had stable disease (SD) of which 6 of these SD pts remain on study ranging from 7-12+ mos. The clinical benefit rate (CR+PR+SD) was 84%, and 91% of pts with at least 1 post-baseline assessment experienced tumor reductions. Median time to initial response was 2.7 mos, while median DOR was not reached (95% CI: 8.4-NR). The 12-month PFS was 71%. The most common all causality (≥20%) adverse events (AE) of any grade included: diarrhea (45%), nausea (29%), fatigue (26%), headache (26%), cough (24%), and decreased appetite (21%). The most common Grade 3/4 events were neutropenia (8%), febrile neutropenia (5%), and diarrhea (5%). As of the cutoff date 58% continue treatment. Conclusions: PI3Kδ inhibition with single-agent umbralisib is active and well tolerated in pts with R/R MZL, achieving durable responses with chemotherapy-free therapy. Clinical trial information: NCT02793583.

Tolerability and activity of ublituximab, umbralisib, and ibrutinib in patients with chronic lymphocytic leukaemia and non-Hodgkin lymphoma: a phase 1 dose escalation and expansion trial

BACKGROUND

Therapeutic approaches for B-cell malignancies continue to evolve, especially with regard to combination approaches. We assessed the safety and efficacy of the triplet ublituximab, umbralisib, and ibrutinib in patients with advanced B-cell malignancies.

METHODS

We did an open-label, phase 1 study with dose-escalation and dose-expansion phases, at five centres in the USA. Eligible patients were aged 18 years or older with histologically confirmed lymphocytic leukaemia or relapsed or refractory B-cell non-Hodgkin lymphoma, had measurable disease, adequate organ function, and an Eastern Cooperative Oncology Group (ECOG) performance status of 2 or less. Patients with known CNS lymphoma, active hepatitis B or C infection, or HIV were excluded. In the dose-escalation cohort, patients were treated in cycles of 28 days with escalating doses of oral umbralisib (400, 600, or 800 mg) and fixed doses of intravenous ublituximab (900 mg) and oral ibrutinib (420 mg for patients with chronic lymphocytic leukaemia; 560 mg for patients with B-cell non-Hodgkin lymphoma) in a standard 3 × 3 design until disease progression or intolerance. In the dose-expansion phase, patients were given the recommended dose of the drug combination as determined from the dose-escalation phase. The primary endpoints were safety, dose-limiting toxicities, and the maximum tolerated dose of umbralisib, when given in combination with ublituximab and ibrutinib. Safety was assessed in patients who received at least one dose of study drug; activity was assessed in all patients who had at least one post-treatment efficacy measurement. The study is ongoing but no longer recruiting patients. This trial is registered with ClinicalTrials.gov, number NCT02006485.

FINDINGS

Between Sept 2, 2014, and Nov 6, 2017, we enrolled 46 patients: 24 in the dose-escalation cohort (n=14 chronic lymphocytic leukaemia or small lymphocytic lymphoma; n=10 B-cell non-Hodgkin lymphoma) and 22 in the dose-expansion cohort (n=9 chronic lymphocytic leukaemia or small lymphocytic lymphoma; n=13 B-cell non-Hodgkin lymphoma). 46 patients received at least one dose of study drug. The maximum tolerated dose of umbralisib was not reached. The recommended dose for the dose-expansion phase was umbralisib 800 mg orally once daily plus ibrutinib orally once daily and intravenous ublituximab 900 mg administered on days 1, 8, and 15 of cycle 1, day 1 of cycles 2-6, and on day 1 of cycles 9 and 12. 37 (84%) of 44 patients achieved an overall response (complete or partial response). The most common any-grade adverse events were diarrhoea (n=27 [59%]), fatigue (n=23 [50%]), infusion-related reaction (n=20 [43%]), dizziness (n=17 [37%]), nausea (n=17 [37%]), and cough (n=16 [35%]). Grade 3-4 adverse events were manageable with the most common being neutropenia (n=10 [22%]) and cellulitis (n=6 [13%]). Serious adverse events occurred in 11 (24%) of 46 patients and included rash (n=2 [4%]), pneumonia (n=2 [4%]), atrial fibrillation (n=2 [4%]), sepsis (n=2 [4%]), abdominal pain (n=1 [2%]), syncope (n=1 [2%]), cellulitis (n=1 [2%]), pneumonitis (n=1 [2%]), headache (n=1 [2%]), lung infection (n=1 [2%]), skin infection (n=1 [2%]), pleural effusion (n=1 [2%]), pericardial infusion (n=1 [2%]), upper gastrointestinal bleeding (n=1 [2%]), diarrhoea (n=1 [2%]), and weakness (n=1 [2%]). No deaths related to adverse events occurred.

INTERPRETATION

The combination of ublituximab, umbralisib, and ibrutinib seems to be tolerable and is associated with encouraging activity in advanced chronic lymphocytic leukaemia and B-cell non-Hodgkin lymphoma. This triplet combination will require further investigation in future studies to improve understanding of this novel, chemotherapy-free triplet combination in the management of these cancers.

FUNDING

TG Therapeutics.

Umbralisib in combination with ibrutinib in patients with relapsed or refractory chronic lymphocytic leukaemia or mantle cell lymphoma: a multicentre phase 1-1b study

BACKGROUND

Patients with relapsed or refractory high-risk chronic lymphocytic leukaemia or mantle cell lymphoma often do not derive durable benefit from ibrutinib monotherapy. We hypothesised that dual B-cell receptor pathway blockade would be tolerable and efficacious. We investigated a next-generation phosphoinositide-3-kinase-δ inhibitor (PI3K-δi), umbralisib, plus a Bruton tyrosine kinase inhibitor (BTKi), ibrutinib, in relapsed or refractory chronic lymphocytic leukaemia and mantle cell lymphoma.

METHODS

We did an investigator-initiated, multicentre, phase 1-1b study of patients from five sites in the USA (academic and community sites). Patients were 18 years and older with relapsed or refractory chronic lymphocytic leukaemia or mantle cell lymphoma, with an Eastern Cooperative Oncology Group performance status of 2 or less, and were given umbralisib orally once daily (400 mg, 600 mg, or 800 mg) and ibrutinib orally once daily (420 mg for chronic lymphocytic leukaemia or 560 mg for mantle cell lymphoma) until disease progression or unacceptable toxicity. The phase 1 dose-escalation cohorts for each histology escalated independently in a standard 3 × 3 design. The primary endpoints were intention-to-treat assessment of maximum-tolerated dose, safety, and dose-limiting toxicities. This trial is ongoing and is registered with ClinicalTrials.gov, number NCT02268851.

FINDINGS

Between Dec 5, 2014, and March 7, 2018, we enrolled 44 patients, of which 42 were given at least one dose of study drug (chronic lymphocytic leukaemia, n=21; mantle cell lymphoma, n=21). Patients had a median age of 68 years (range 48-85) and had a median of two (IQR 1-3) previous therapies. No dose-limiting toxicities were observed and the maximum-tolerated dose of umbralisib was not reached. The recommended phase 2 dose of umbralisib when given in combination with ibrutinib was 800 mg once daily. The most frequent adverse events included diarrhoea (22 [52%] patients, 10% of whom had grade 3), infection (21 [50%], 17% grade 3-4), and transaminitis (ten [24%], 2% grade 3). Serious adverse events occurred in 12 (29%) patients and included lipase elevation, atrial fibrillation, hypophosphataemia, adrenal insufficiency, transaminitis, and infections.

INTERPRETATION

Umbralisib plus ibrutinib is well tolerated and active in relapsed or refractory chronic lymphocytic leukaemia and mantle cell lymphoma, with a recommended phase 2 dose of umbralisib 800 mg once daily. To the best of our knowledge, these are the first clinical data on a BTKi and PI3K-δi doublet in B-cell malignancies, and the results suggest that this approach is feasible and worthy of further study.

FUNDING

TG Therapeutics, Leukemia and Lymphoma Society Therapy Accelerator Program.

Abstract 5790: TG-1601 is a novel BET inhibitor with strong binding affinity and long-lasting effect in pre-clinical models

BET (bromodomain and extra-terminal) proteins bind to acetylated lysine residues on chromatin and participate in the regulation of gene transcription. Inhibition of BET protein binding to chromatin with small molecules selectively suppresses the transcription of a set of oncogenes, including MYC and BCL-2. TG-1601 is a novel, selective and potent small molecule inhibitor of BET bromodomains. TG-1601 binds to the first and second bromodomains (BD1, BD2) of the BET protein family, BRD2, BRD3, BRD4, and BRDT, with Kd values ranging from 0.5 nM to 9.1 nM. MYC protein expression is strongly inhibited in the MV4-11 cancer cell line with an EC50 of 5 nM, with GI50 comprised between 15 nM and 85 nM in a variety of leukemia and myeloma cancer cell lines, indicating potent inhibition of cell proliferation. Time course and dose-response studies conducted in mice bearing subcutaneous MV4-11 xenografts showed that MYC protein was undetectable 3 hours following a single 25 mg/kg oral dose, with a TG-1601 tumor concentration of 6uM achieved. Interestingly, at 24h post-dose, while TG-1601 is cleared from the tumor, MYC protein level remains below 40% of its initial level, indicating a long-lasting effect pharmacodynamic of TG-1601, potentially attributable to enhanced binding affinity compared to earlier generation molecules. In agreement with this long-lasting effect, efficacy studies in MV4-11 tumor-bearing mice, dosed with a 20 mg/kg/day PO regimen interrupted by increasing drug holiday periods, showed that drug holidays of 2, 3 and 4 days per week only modestly affected efficacy (3%, 15% and 12% TGI respectively), suggesting discontinuous dosing of TG-1601 in clinic may not significantly impact efficacy. Anti-cancer agents have been shown - in vitro or in vivo - to synergize with BET inhibitors. Here we show that TG-1601 and anti PD-1 antibody demonstrated synergistic anti-tumor activity when combined in the B16F10 model, an aggressive syngeneic model of melanoma. TG-1601 inhibition of MYC, CCR-2 and IL1RN gene expression was tested in a whole blood ex-vivo experiment, and the genes were validated as pharmacodynamic markers to monitor TG-1601 activity in clinic. In conclusion, TG-1601 is a novel BET inhibitor with remarkably strong affinity and a potent ability to inhibit MYC expression and cell growth, with favorable pharmacokinetic properties supporting clinical development. Its properties in vivo provide an opportunity for the rational development of TG-1601 as an anti-cancer agent, taken alone or in combination with other small molecules or antibodies. IND enabling studies are underway, with clinical evaluation expected to commence in the first half of 2018.

Citation Format: Emmanuel Normant, Leonid Gorelik, Rama Shmeis, Henry Le, Robert Nisch, Karen TenHuisen, Teja Turpuseema, James Oliviero, Hari P. Miskin, Peter Sportelli, Michael S. Weiss. TG-1601 is a novel BET inhibitor with strong binding affinity and long-lasting effect in pre-clinical models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5790.

Tolerability and activity of chemo-free triplet combination of TGR-1202, ublituximab, and ibrutinib in patients with advanced CLL and NHL

7511

Background: Novel targeted agents are emerging for B-cell malignancies, but few studies have safely combined these agents. Ublituximab (UTX) is a novel glycoengineered mAb targeting a unique epitope on the CD20 antigen. TGR-1202 is a next generation, once daily PI3Kδ inhibitor, demonstrating a favorable safety profile compared to prior inhibitors, including in long-term follow up (Burris, 2016). This Ph 1 trial evaluates the safety/efficacy of the triplet combination of a novel anti-CD20 mAb + PI3Kδ + BTK inhibitor (ibrutinib) in pts with B-cell malignancies. Methods: Eligible pts had CLL or rel/ref NHL w/o limit to prior therapies, including those ref to prior PI3Kδ or BTK inhibitors. UTX dosed on D1, 8, 15 of C1; D1 of C2-6, and C9 & 12. TGR-1202 dose escalated (400/600/800mg QD), ibrutinib dosed at 420mg (CLL) or 560mg (NHL), both on C1D1. Results: 38 pts were enrolled: 20 CLL/SLL and 18 NHL, including 6 follicular (FL), 6 DLBCL, 4 mantle cell (MCL) and 2 marginal zone (MZL). Med age 65 yrs (range 32-85); 29 M/9 F; med prior tx = 3 (range 0-6). 2 pts were ref to prior PI3Kδ and 2 were prev treated with ibrutinib (1 ref/1 rel). MTD was not reached. Most common ( > 20%) all causality AE’s were fatigue (42%), diarrhea (39%), dizziness (34%), nausea (32%), neutropenia, pyrexia, rash, infusion reaction, insomnia (each at 29%), thrombocytopenia, cough (each at 26%), anemia (24%) and sinusitis (21%). GR 3/4 AE’s were minimal, the only event > 10% was neutropenia (16%). ORR amongst 36 evaluable pts is shown in the table below. 53% of evaluable CLL pts had high-risk cytogenetics and 4/6 DLBCL pts were non-GCB. One CLL pt (17p/11q del) ref to both PI3Kδ and ibrutinib achieved a CR. Med time on study is 10 mos (range 1 – 27+ mos). Med DOR not reached (range 3 – 24+ mos). Conclusions: This is the first known triple combination of an anti-CD20 mAb + PI3Kδ + BTK inhibitor. The combination of UTX, TGR-1202, and ibrutinib has been well tolerated with activity observed across heavily pre-treated and high-risk B-cell malignancies. Expansion cohorts at the highest dose (800mg TGR-1202 + full dose ibrutinib) are underway. Future trials for the triplet are warranted. Clinical trial information: NCT02006485. [Table: see text]

Ublituximab and ibrutinib for previously treated genetically high-risk chronic lymphocytic leukemia: Results of the GENUINE phase 3 study

7504

Background: Patients (pts) with high-risk chronic lymphocytic leukemia (CLL) defined by interruptions in TP53 (either by mutation or deletion) or loss of chromosome 11q experience inferior outcomes with ibrutinib (IB) monotherapy (O’Brien ASH 2016). Ublituximab (UTX) is a novel glycoengineered mAb with enhanced ADCC targeting a unique epitope on the CD20 antigen. GENUINE is the first randomized Ph 3 trial conducted assessing the addition of a novel agent to ibrutinib in high-risk rel/ref CLL, and evaluates IB monotherapy vs. UTX + IB. Methods: Eligible pts with rel/ref CLL and centrally confirmed del17p, del11q, and/or a TP53 mutation were randomized 1:1 to receive IB (420 mg QD) alone or with UTX (900 mg on D1, 8, 15 of Cycle 1, D1 of Cycle 2-6, and Q3 Cycles thereafter). There was no limit on number of prior therapies. Prior IB exposure was excluded. The primary endpoint was overall response rate (ORR) per iwCLL 2008 criteria, with secondary endpoints including CR rate, MRD negativity, PFS, time to response (TTR) and safety. Results: 126 pts were randomized at sites in the US and Israel, with 117 pts treated (59 on UTX + IB, 58 on IB alone). Median age 67, median 3 prior therapies (range 1-8), > 70% of were male. High-risk cytogenetics were relatively balanced with ~ 50% of pts having del17p. UTX+IB was well tolerated, with infusion reactions the most prevalent AE (44%, GR3/4 5%). Neutropenia was comparable with the combination (17%, Gr3/4 7% vs. 10%, Gr3/4 9%), and other AE’s were similar or lower with UTX+IB vs. IB alone (all grades), including fatigue (17% vs. 31%), dizziness (12% vs. 21%), contusion (12% vs. 26%), anemia (10% vs. 16%), and myalgia (9% vs. 14%). At median follow-up of 12 mo, best ORR per independent central review was 80% for UTX + IB vs. 47% for IB alone (p < 0.001). While not powered for secondary endpoints, observed advantages were seen in PFS and radiographic CR rate in the UTX + IB arm. CR and MRD confirmation is ongoing. Median TTR for the combo was 1.97 mo vs. 3.8 mo for IB alone. Both arms have responses pending confirmatory assessments. Conclusions: The addition of UTX to IB demonstrated a superior response rate compared to IB alone without additional clinically significant toxicity. Clinical trial information: NCT02301156.

KI intolerance study: A phase 2 study to assess the safety and efficacy of TGR-1202 in pts with chronic lymphocytic leukemia (CLL) who are intolerant to prior BTK or PI3K-delta inhibitor therapy

TPS7569

Background: Although kinase inhibitor (KI) therapies, such as ibrutinib, are generally well tolerated, intolerance is the most common reason for discontinuation (d/c) in practice (~50%, Mato et al, Blood 2016). Additionally KI interruptions (≥ 8 days) can shorten OS (Barr et al, ASCO 2015). Fortunately, data suggest that KIs have non-overlapping toxicity profiles. Therefore, pts who d/c KI due to intolerance, with ongoing CLL response, represent an unmet need. TGR-1202 is a next generation, highly-specific PI3K-delta inhibitor with nanomolar inhibitory potency. TGR-1202 is well-tolerated with a d/c rate due to AEs of 8% as demonstrated in an integrated safety analysis of 165 treated pts (Burris et al, ASCO 2016). Methods: A phase 2 investigator initiated study is being conducted to assess the safety and activity of TGR-1202 in CLL pts who are KI intolerant. KI Intolerance is defined as ≥ 1 Gr 3 or ≥ 2 Gr 2 non-heme toxicities, ≥ 1 Gr 3 neutropenia with infection or fever, and/or ≥ 1 Gr 4 heme toxicity leading to KI (BTK and/or PI3K inhibitor) d/c (Table). Toxicities must resolve to ≤ Gr 1 prior to TGR-1202 dosing. Prior KI must be d/c for ≥ 14 days without progression (PD). All eligible pts are treated with TGR-1202 (800mg oral daily) until PD, toxicity or study conclusion. Primary study endpoint is PFS. Secondary endpoints include ORR, duration of response, time to treatment failure and TGR-1202 safety profile. Peripheral blood samples are collected prior to TGR-1202, after 28 days and at PD for correlative analyses to identify markers associated with KI intolerance. The trial commenced 10/1/2016. 55 eligible pts will be enrolled in approximately 12 months with 24 months follow-up. As of 1/2017, 10 study sites are enrolling pts with 10 more to be activated. To date, 10 pts have been enrolled and treated with TGR-1202. Clinical trial information: NCT02742090. [Table: see text]

A phase 1/2 trial of ublituximab, a novel anti-CD20 monoclonal antibody, in patients with B-cell non-Hodgkin lymphoma or chronic lymphocytic leukaemia previously exposed to rituximab

This phase 1/2 study evaluated the safety, pharmacokinetic behavior and anti‐tumour activity of ublituximab, a unique type I, chimeric, glycoengineered anti‐CD20 monoclonal antibody, in rituximab‐relapsed or ‐refractory patients with B‐cell non‐Hodgkin lymphoma (B‐NHL) or chronic lymphocytic leukaemia (CLL). Induction therapy (doses of 450–1200 mg) consisted of 4 weekly infusions in cycle 1 for NHL and 3 weekly infusions in cycles 1 and 2 for CLL. Patients received ublituximab maintenance monthly during cycles 3–5, then once every 3 months for up to 2 years. Enrolled patients with B‐NHL (n = 27) and CLL (n = 8) had a median of 3 prior therapies. No dose‐limiting toxicities or unexpected adverse events (AEs) occurred. The most common AEs were infusion‐related reactions (40%; grade 3/4, 0%); fatigue (37%; grade 3/4, 3%); pyrexia (29%; grade 3/4, 0%); and diarrhoea (26%; grade 3/4, 0%). Common haematological AEs were neutropenia (14%; grade 3/4, 14%) and anaemia (11%; grade 3/4, 6%). The overall response rate for evaluable patients (n = 31) was 45% (13% complete responses, 32% partial responses). Median duration of response and progression‐free survival were 9·2 months and 7·7 months, respectively. Ublituximab was well‐tolerated and efficacious in a heterogeneous and highly rituximab‐pre‐treated patient population.

Ublituximab (TG-1101), a novel glycoengineered anti-CD20 antibody, in combination with ibrutinib is safe and highly active in patients with relapsed and/or refractory chronic lymphocytic leukaemia: results of a phase 2 trial

Ibrutinib is effective in patients with chronic lymphocytic leukaemia (CLL); however, treatment resistance remains a problem. Ublituximab is a novel, glycoengineered anti-CD20 monoclonal antibody with single-agent activity in relapsed CLL. We report the results of a phase 2 study evaluating combination therapy with ibrutinib and ublituximab in patients with relapsed or refractory CLL. Patients received ibrutinib 420 mg once daily. Ublituximab was administered on days 1, 8 and 15 of cycle 1 followed by day 1 of cycles 2-6. Response assessments were completed at cycles 3 and 6; patients then continued on ibrutinib monotherapy per standard of care. Forty-one of 45 enrolled patients were evaluable for efficacy. Safety was consistent with prior experience for each drug, with infusion reactions the most prevalent adverse event. Combination therapy resulted in an overall response rate (ORR) of 88% at 6 months. In the 20 patients with high-risk features (17p or 11q deletions or TP53 mutation) and evaluable for efficacy, the ORR was 95%, with three patients (15%) achieving negative minimal residual disease. Median time to response was 8 weeks. Ublituximab in combination with ibrutinib resulted in rapid and high response rates. The long-term clinical benefit of ublituximab will be defined by an ongoing phase 3 trial (NCT 02301156).

Abstract 4518: The PI3K-δ inhibitor TGR-1202 induces cytotoxicity and inhibits phosphorylation of AKT in 17p deleted and non-17p deleted CLL cells in vitro

Background: The PI3K pathway is a central pro-survival mechanism in chronic lymphocytic leukemia (CLL), with expression of the delta isoform of PI3K largely restricted to lymphocytes. Clinical evaluation of PI3K-δ inhibitors, such as idelalisib, in CLL patients has been promising. CLL patients with 17p deletion (17pdel) have displayed inferior responses to chemo-immunotherapy, and we hypothesized that inhibiting the PI3K/AKT pathway would be equally efficacious in patients with and without 17pdel. TGR-1202 is a novel PI3K-δ specific inhibitor with unique pharmacologic properties and demonstrated in-vitro activity. Herein, we evaluate the in vitro effect of TGR-1202 on CLL lymphocytes, specifically evaluating differences between 17pdel CLL and non-17pdel CLL samples.

Methods: We collected blood from CLL patients seen at the Duke Center for CLL and enrolled in IRB approved protocols at the Duke University and Durham VA Medical Centers. CLL lymphocytes were isolated using negative selection yielding greater than 95% purity. Primary CLL cells were incubated with serial dilutions of TGR-1202 tested for apoptosis by activated caspase-3 and 7AAD staining measured by flow cytometry. Cytotoxicity was measured using the colorimetric MTS reagent. Phosphorylated AKT (S473) was measured by flow cytometry after incubation with TGR-1202 followed by incubation with anti-IgM or anti-IgD. AKT phosphorylation was quantified by median fluorescent intensity (MFI).

Results: We have evaluated TGR-1202 in 15 CLL lymphocyte samples, 10 with normal non-17pdel cytogenetics, and 5 with 17pdel. TGR-1202 induced cytotoxicity and apoptosis in a dose-dependent manner in concentrations between 4 nM and 25 μM with no significant difference in results observed between normal CLL lymphocytes those that had 17pdel cytogenetics. The mean ED50 in 17pdel CLL cells was 326 nM, whereas the mean ED50 in non-17pdel CLL cells was 887 nM, although due to the small sample size, this difference was not statistically significant (p = 0.16, t-test). We also found that TGR-1202 significantly suppressed AKT phosphorylation in CLL lymphocytes.

Conclusions: TGR-1202 is a potent PI3K-δ inhibitor that suppresses AKT phosphorylation and induces apoptosis-dependent cytotoxicity in primary CLL lymphocytes, both with favorable and adverse cytogenetics. We observed that higher concentrations of TGR-1202 were required to induce cytotoxicity in non-17pdel CLL lymphocytes on average, than in 17pdel CLL. Evaluation of additional CLL cell samples with 17pdel is ongoing to confirm initial findings. A Phase I trial with once-daily TGR-1202 is currently ongoing in patients with hematologic malignancies, including CLL. To date, TGR-1202 has been well tolerated, with no drug-related hepatic toxicities observed. Our initial observations suggest that clinical evaluation of TGR-1202 enriched in CLL patients with 17pdel may be warranted.

Citation Format: Daphne R. Friedman, Tiffany Simms, Sallie D. Allgood, Danielle M. Brander, Peter Sportelli, Hari P. Miskin, Swaroop Vakkalanka, Srikant Viswanadha, J. Brice Weinberg, Mark C. Lanasa. The PI3K-δ inhibitor TGR-1202 induces cytotoxicity and inhibits phosphorylation of AKT in 17p deleted and non-17p deleted CLL cells in vitro. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4518. doi:10.1158/1538-7445.AM2014-4518