Pooled Analysis of Pralatrexate Single-Agent Studies in Patients With Relapsed/Refractory Peripheral T-Cell Lymphoma

Patients with relapsed or refractory (r/r) mature NK and T-cell lymphoma (MTCL) have limited treatment options. To evaluate pralatrexate's performance and factors influencing its safety and efficacy in r/r PTCL, we performed a pooled analysis of data from four similarly designed, regulatory-mandated prospective clinical trials. Of 221 patients (59 years median age; 67.0% male) in the study population, 48.9% had peripheral T-cell lymphoma not otherwise specified (PTCL-NOS), 21.3% angioimmunoblastic T-cell lymphoma, and 11.8% ALK negative anaplastic large cell lymphoma (ALCL). Patients received pralatrexate for a median 2.56 months (range, 0.03-24.18) and had a 40.7% objective response rate with a median 9.1-month duration of response, 4.6-month progression-free survival, and 16.3-month overall survival. The most common treatment-related all grade adverse events were stomatitis, thrombocytopenia, white blood cell count decreased, pyrexia, and vomiting. Subgroup exploratory analyses suggest improved efficacy with 1 prior line of chemotherapy versus 2 or ≥ 4 prior lines; PTCL NOS or ALCL versus transformed mycosis fungoides; chemotherapy and transplant before pralatrexate versus chemotherapy alone or chemotherapy with other non-transplant treatments. In conclusion, these pooled analysis results further support using pralatrexate in patients with r/r PTCL. Prospective studies are needed to confirm the findings of subgroups analyses.

Mature T-cell and NK-cell lymphoma involvement of the central nervous system: a single center experience

Mature T-cell and NK-cell lymphomas (MTNKL) are rare and heterogeneous lymphoproliferative disorders with poor clinical outcomes despite novel therapeutic advances. Although infrequent, central nervous system (CNS) involvement by MTNKL is associated with poor outcomes with a median overall survival (OS) of <12 months based on retrospective studies. We performed a retrospective analysis of patients who developed CNS involvement of MTNKL diagnosed at a single center from 1999 through 2020. Twenty-five patients were identified. Characteristics such as a diagnosis of adult T-cell leukemia/lymphoma, extranodal involvement, and poor performance status were associated with a higher risk of CNS involvement (p < 0.01). The median OS after diagnosis with CNS involvement was approximately 1 month (0.03-103.97 months). Patients exposed to novel therapeutics and/or clinical trial enrollment tolerated treatment without safety concerns and appeared to derive reasonable therapeutic benefit. Despite advances in the field, new therapeutic approaches are needed for patients with MTNKL with CNS involvement.

HX009, a novel BsAb dual targeting PD1 x CD47, demonstrates potent anti-lymphoma activity in preclinical models

Both PD1/PD-L1 and CD47 blockades have demonstrated limited activity in most subtypes of NHL save NK/T-cell lymphoma. The hemotoxicity with anti-CD47 agents in the clinic has been speculated to account for their limitations. Herein we describe a first-in-class and rationally designed bispecific antibody (BsAb), HX009, targeting PD1 and CD47 but with weakened CD47 binding, which selectively hones the BsAb for tumor microenvironment through PD1 interaction, potentially reducing toxicity. In vitro characterization confirmed: (1) Both receptor binding/ligand blockade, with lowered CD47 affinity; (2) functional PD1/CD47 blockades by reporter assays; (3) T-cell activation in Staphylococcal-enterotoxin-B-pretreated PBMC and mixed-lymphocyte-reaction. In vivo modeling demonstrated antitumor activity in Raji-B and Karpass-229-T xenograft lymphomas. In the humanized mouse syngeneic A20 B-lymphoma (huCD47-A20) HuGEMM model, which has quadruple knocked-in hPD1xhPD-L1xhCD47xhSIRPα genes and an intact autologous immune-system, a contribution of effect is demonstrated for each targeted biologic (HX008 targeting PD1 and SIRPα-Fc targeting CD47), which is clearly augmented by the dual targeting with HX009. Lastly, the expression of the immune-checkpoints PD-L1/L2 and CD47 seemed co-regulated among a panel of lymphoma-derived-xenografts, where HX009 maybe more effective in those with upregulated CD47. Our data warrants HX009's further clinical development for treating NHLs.

The ECHELON-2 Trial: 5-year results of a randomized, phase 3 study of brentuximab vedotin with chemotherapy for CD30-positive peripheral T-cell lymphoma

Background:

For patients with peripheral T-cell lymphoma (PTCL), outcomes using frontline treatment with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) or CHOP-like therapy are typically poor. The ECHELON-2 study demonstrated that brentuximab vedotin plus cyclophosphamide, doxorubicin, and prednisone (A+CHP) exhibited statistically superior progression-free survival (PFS) per independent central review and improvements in overall survival versus CHOP for the frontline treatment of patients with systemic anaplastic large cell lymphoma or other CD30-positive PTCL.

Patients and methods:

ECHELON-2 is a double-blind, double-dummy, randomized, placebo-controlled, active-comparator phase III study. We present an exploratory update of the ECHELON-2 study, including an analysis of 5-year PFS per investigator in the intent-to-treat analysis group.

Results:

A total of 452 patients were randomized (1 : 1) to six or eight cycles of A+CHP (N = 226) or CHOP (N = 226). At median follow-up of 47.6 months, 5-year PFS rates were 51.4% [95% confidence interval (CI): 42.8% to 59.4%] with A+CHP versus 43.0% (95% CI: 35.8% to 50.0%) with CHOP (hazard ratio = 0.70; 95% CI: 0.53–0.91), and 5-year overall survival (OS) rates were 70.1% (95% CI: 63.3% to 75.9%) with A+CHP versus 61.0% (95% CI: 54.0% to 67.3%) with CHOP (hazard ratio = 0.72; 95% CI: 0.53–0.99). Both PFS and OS were generally consistent across key subgroups. Peripheral neuropathy was resolved or improved in 72% (84/117) of patients in the A+CHP arm and 78% (97/124) in the CHOP arm. Among patients who relapsed and subsequently received brentuximab vedotin, the objective response rate was 59% with brentuximab vedotin retreatment after A+CHP and 50% with subsequent brentuximab vedotin after CHOP.

Conclusions:

In this 5-year update of ECHELON-2, frontline treatment of patients with PTCL with A+CHP continues to provide clinically meaningful improvement in PFS and OS versus CHOP, with a manageable safety profile, including continued resolution or improvement of peripheral neuropathy.

Characterization of newly established Pralatrexate-resistant cell lines and the mechanisms of resistance

Background

Pralatrexate (PDX) is a novel antifolate approved for the treatment of patients with relapsed/refractory peripheral T-cell lymphoma, but some patients exhibit intrinsic resistance or develop acquired resistance. Here, we evaluated the mechanisms underlying acquired resistance to PDX and explored potential therapeutic strategies to overcome PDX resistance.

Methods

To investigate PDX resistance, we established two PDX-resistant T-lymphoblastic leukemia cell lines (CEM and MOLT4) through continuous exposure to increasing doses of PDX. The resistance mechanisms were evaluated by measuring PDX uptake, apoptosis induction and folate metabolism-related protein expression. We also applied gene expression analysis and methylation profiling to identify the mechanisms of resistance. We then explored rational drug combinations using a spheroid (3D)-culture assay.

Results

Compared with their parental cells, PDX-resistant cells exhibited a 30-fold increase in half-maximal inhibitory concentration values. Induction of apoptosis by PDX was significantly decreased in both PDX-resistant cell lines. Intracellular uptake of [¹⁴C]-PDX decreased in PDX-resistant CEM cells but not in PDX-resistant MOLT4 cells. There was no significant change in expression of dihydrofolate reductase (DHFR) or folylpolyglutamate synthetase (FPGS). Gene expression array analysis revealed that DNA-methyltransferase 3β (DNMT3B) expression was significantly elevated in both cell lines. Gene set enrichment analysis revealed that adipogenesis and mTORC1 signaling pathways were commonly upregulated in both resistant cell lines. Moreover, CpG island hypermethylation was observed in both PDX resistant cells lines. In the 3D-culture assay, decitabine (DAC) plus PDX showed synergistic effects in PDX-resistant cell lines compared with parental lines.

Conclusions

The resistance mechanisms of PDX were associated with reduced cellular uptake of PDX and/or overexpression of DNMT3B. Epigenetic alterations were also considered to play a role in the resistance mechanism. The combination of DAC and PDX exhibited synergistic activity, and thus, this approach might improve the clinical efficacy of PDX.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08607-9.

Targeting the T-Cell Lymphoma Epigenome Induces Cell Death, Cancer Testes Antigens, Immune-Modulatory Signaling Pathways

The peripheral T-cell lymphomas (PTCL) could be considered the prototypical epigenetic disease. As a disease, they are uniquely sensitive to histone deacetylase (HDAC) and DNA methyltransferase (DNMT) inhibitors, both alone and in combination, are characterized by a host of mutations in epigenetic genes, and can develop spontaneously in genetically engineered murine models predicated on established recurring mutations in (RHOAG17V) and TET2, an epigenetic gene governing DNA methylation. Given the clinical benefit of HDAC inhibitors (HDACi) and hypomethlyation agents alone and in combination in PTCL, we sought to explore a mechanistic basis for these agents in PTCL. Herein, we reveal profound class synergy between HDAC and DNMT inhibitors in PTCL, and that the combination induces degrees of gene expression that are substantially different and more extensive than that observed for the single agents. A prominent signature of the combination relates to the transcriptional induction of cancer testis antigens and genes involved in the immune response. Interestingly, TBX21 and STAT4, master regulators of TH1 differentiation, were among the genes upregulated by the combination, suggesting the induction of a TH1-like phenotype. Moreover, suppression of genes involved in cholesterol metabolism and the matrisome were also identified. We believe that these data provide a strong rationale for clinical studies, and future combinations leveraging an immunoepigenetic platform.

R-Loop-Mediated ssDNA Breaks Accumulate Following Short-Term Exposure to the HDAC Inhibitor Romidepsin

Histone deacetylase inhibitors (HDACi) induce hyperacetylation of histones by blocking HDAC catalytic sites. Despite regulatory approvals in hematological malignancies, limited solid tumor clinical activity has constrained their potential, arguing for better understanding of mechanisms of action (MOA). Multiple activities of HDACis have been demonstrated, dependent on cell context, beyond the canonical induction of gene expression. Here, using a clinically relevant exposure duration, we established DNA damage as the dominant signature using the NCI-60 cell line database and then focused on the mechanism by which hyperacetylation induces DNA damage. We identified accumulation of DNA-RNA hybrids (R-loops) following romidepsin-induced histone hyperacetylation, with single-stranded DNA (ssDNA) breaks detected by single-cell electrophoresis. Our data suggest that transcription-coupled base excision repair (BER) is involved in resolving ssDNA breaks that, when overwhelmed, evolve to lethal dsDNA breaks. We show that inhibition of BER proteins such as PARP will increase dsDNA breaks in this context. These studies establish accumulation of R-loops as a consequence of romidepsin-mediated histone hyperacetylation. We believe that the insights provided will inform design of more effective combination therapy with HDACis for treatment of solid tumors. IMPLICATIONS: Key HDAC inhibitor mechanisms of action remain unknown; we identify accumulation of DNA-RNA hybrids (R-loops) due to chromatin hyperacetylation that provokes single-stranded DNA damage as a first step toward cell death.

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]

Management of Angioimmunoblastic T-Cell Lymphoma (AITL) and other T Follicular Helper Cell lymphomas (TFH PTCL)

Despite the remarkable improvements in the treatment and outcome of patients with aggressive B-cell lymphoma, the peripheral T-cell lymphomas (PTCL) continue to carry a poor prognosis with the presently available treatment options. The PTCL are very rare diseases that account for only 10,000 to 15,000 new cases per year in the United States. The World Health Organization's 2016 classification describes 29 distinct subtypes of PTCL, thus making these both rate and incredibly heterogenous. The 2 most common forms of PTCL, for example, peripheral T-cell lymphoma-not otherwise specified and angioimmunoblastic T-cell lymphoma , have an incidence of only 2500 and 1800 cases per year respectively, in the United States.

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.

Phase I Study of the CD47 Blocker TTI-621 in Patients with Relapsed or Refractory Hematologic Malignancies

PURPOSE

TTI-621 (SIRPα-IgG1 Fc) is a novel checkpoint inhibitor that activates antitumor activity by blocking the CD47 "don't eat me" signal. This first-in-human phase I study (NCT02663518) evaluated the safety and activity of TTI-621 in relapsed/refractory (R/R) hematologic malignancies.

PATIENTS AND METHODS

Patients with R/R lymphoma received escalating weekly intravenous TTI-621 to determine the maximum tolerated dose (MTD). During expansion, patients with various malignancies received weekly single-agent TTI-621 at the MTD; TTI-621 was combined with rituximab in patients with B-cell non-Hodgkin lymphoma (B-NHL) or with nivolumab in patients with Hodgkin lymphoma. The primary endpoint was the incidence/severity of adverse events (AEs). Secondary endpoint included overall response rate (ORR).

RESULTS

Overall, 164 patients received TTI-621: 18 in escalation and 146 in expansion (rituximab combination, n = 35 and nivolumab combination, n = 4). On the basis of transient grade 4 thrombocytopenia, the MTD was determined as 0.2 mg/kg; 0.1 mg/kg was evaluated in combination cohorts. AEs included infusion-related reactions, thrombocytopenia, chills, and fatigue. Thrombocytopenia (20%, grade ≥3) was reversible between doses and not associated with bleeding. Transient thrombocytopenia that determined the initial MTD may not have been dose limiting. The ORR for all patients was 13%. The ORR was 29% (2/7) for diffuse large B-cell lymphoma (DLBCL) and 25% (8/32) for T-cell NHL (T-NHL) with TTI-621 monotherapy and was 21% (5/24) for DLBCL with TTI-621 plus rituximab. Further dose optimization is ongoing.

CONCLUSIONS

TTI-621 was well-tolerated and demonstrated activity as monotherapy in patients with R/R B-NHL and T-NHL and combined with rituximab in patients with R/R B-NHL.

N-quinoline-benzenesulfonamide derivatives exert potent anti-lymphoma effect by targeting NF-κB

We previously identified the N-quinoline-benzenesulfonamide (NQBS) scaffold as a potent inhibitor of nuclear factor-κB (NF-κB) translocation. Now, we report the structure-activity relationship of compounds with the NQBS scaffold in models of diffuse large B-cell lymphoma (DLBCL). We identified CU-O42, CU-O47, and CU-O75 as NQBS analogs with the most potent cytotoxic activity in DLBCL lines. Their anti-lymphoma effect was mediated by NF-κB sequestration to the cytoplasm of DLBCL cells. Internal Coordinates Mechanics analysis suggested direct binding between CU-O75 and IκBα/p50/p65 which leads to the stabilization of the NF-κB trimer. A whole cellular thermal shift assay confirmed direct binding of the NQBS to IκBα, an inhibitory component of the IκBα/p50/p65 trimer. Lymphoma cell line sequencing revealed CU-O75 induced downregulation of NF-κB-dependent genes and DeMAND analysis identified IκBα as one of the top protein targets for CU-O75. CU-O42 was potent in inhibiting tumor growth in two mouse models of aggressive lymphomas.

A perspective on improving the R-CHOP regimen: from Mega-CHOP to ROBUST R-CHOP, the PHOENIX is yet to rise

The integration of rituximab (R) into cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) by Coiffier and colleagues was the first, and last, successful modification of this backbone regimen, which has endured now for almost 20 years. Countless attempts to redefine R-CHOP for patients with diffuse large B-cell lymphoma (DLBCL) have migrated from a focus on dose-intense and dose-dense regimens, to the use of maintenance therapies, and most recently the addition of novel agents. To date, none have changed the basic formula. Although there are many reasons for the absence of success, the incredible molecular heterogeneity of DLBCL is likely to be a major complicating factor. It is clear that as the scientific field's understanding of the genetic heterogeneity of DLBCL deepens, a precision medicine approach should be accounted for and might be one of several paths that could lead to improved outcomes. The rapid identification of poor prognostic groups within the evolving diverse molecular landscape of DLBCL will create new opportunities to produce the next generation of studies with targeted agents against specific pathological drivers. It is conceivable that targeting these driver pathways will require more than one agent, and of course, splitting the pool of patients with DLBCL into smaller groups on the basis of molecular characteristics, will reduce the number of eligible patients for clinical trial investigation. The integration of immunological agents might afford new opportunities to develop treatments agnostic to the complex molecular diversity, while adding minimal toxicity to the regimen. With each of these iterations, the hope is to ultimately shift away from a one-size-fits-all chemotherapy mentality to one predicated on an individualised approach, whether that be through the use of a targeted small molecule or a biological drug. In this Viewpoint, we explore the history of the collective efforts to improve upon R-CHOP, and underscore those lessons that might help to reshape our future plans.

Generation of pralatrexate resistant T-cell lymphoma lines reveals two patterns of acquired drug resistance that is overcome with epigenetic modifiers

While pralatrexate (PDX) has been successfully developed for the treatment of T-cell lymphoma, the mechanistic basis for its T-cell selectivity and acquired resistance remains elusive. In an effort to potentially identify synergistic combinations that might circumnavigate or delay acquired PDX resistance, we generated resistant cells lines over a broad concentration range. PDX-resistant cell lines H9-12 and H9-200 were developed, each exhibiting an IC50 of 35 and over 1000 nM, respectively. These lines were established in vitro from parental H9 cells. Expression analysis of the proteins known to be important determinants of antifolate pharmacology revealed increase expression of dihydrofolate reductase (DHFR) due to gene amplification, and reduced folate carrier1 downregulation, as the putative mechanisms of resistance in H9-12 and H9-200 cells. Cross resistance was only seen with methotrexate but not with romidepsin, azacitidine (AZA), decitabine, gemcitabine, doxorubicin, or bortezomib. Resistance to PDX was reversed by pretreatment with hypomethylating agents in a concentration-dependent fashion. Comparison of gene expression profiles of parental and resistant cell lines confirmed markedly different patterns of gene expression, and identified the dual specificity phosphatase four (DUSP4) as one of the molecular target of PDX activity. Reduced STAT5 phosphorylation following exposure to PDX was observed in the H9 but not in the H9-12 and H9-200 cells. These data suggest that combination with hypomethylating agents could be potent, and that DUSP4 and STAT5 could represent putative biomarkers of PDX activity.

A survey of cancer testis antigen (CTA) expression across T-cell lymphoma subtypes

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Background: T-cell lymphomas (TCL) are a rare and heterogeneous group of non-Hodgkin lymphomas (NHL) that originate from T- and NK-cells and portends a poor prognosis. One promising therapeutic strategy involves generation of tumor associated antigen directed T-cells (TAA-T) against specific CTA. RNAseq have established that combinations of histone deacetylase inhibitors and hypomethylating agents uniquely induce genes characterized as cancer testes antigens (CTA), which may increase immunogenicity. There is a lack of data on the baseline expression of CTA across the TCL, limiting application of TAA-T. We sought to establish the baseline expression of CTA in PTCL using immunohistochemistry to better understand treatment effects. Methods: A tissue microarray was created using formalin-fixed paraffin embedded tissue from 40 patients with diverse T-cell neoplasms. Expression of WT1, SCP1, survivin, PLAC1, SSX2, and PRAME was evaluated by immunohistochemistry. The percentage of positive tumor cells (divided into quartiles), staining intensity (weak, moderate, strong), and subcellular localization (nuclear, cytoplasmic) was assessed. Results: Forty patients with T-cell lymphomas were included in the analysis. The median age of diagnosis and median number of treatments was 60.2 years and 2 (0-9), respectively. Thirty-nine (98%) patients expressed at least one CTA. A high frequency of survivin, which is associated with cell proliferation and is expressed on normal lymphoid tissue, was expressed in 98% of TCL, 5% expressed WT1, and 12.5% expressed SCP1, and expression of other CTA was not observed. Of five patients with anaplastic large cell lymphoma, 3 samples were positive for SCP1 and one was also positive for WT1. One of 9 angioimmunoblastic T-cell lymphoma samples was positive for SCP1. Of 4 T-lymphoblastic lymphoma patients, 1 was positive for WT1, and of 3 transformed mycosis fungoides specimens, 1 demonstrated SCP1 expression. In this sample set, we did not find a correlation with expression and response to chemotherapy. There were no patients with CTA expression who were treated with epigenetic treatments. Conclusions: We described low expression of CTA on T-cell lymphomas, which is consistent with the literature on expression by RT-PCR. By establishing this baseline expression of CTA, we have the foundation on which to measure changes in CTA expression pre- and post-treatment by immunohistochemistry.

The Integration of PD1 blockade with epigenetic therapy is highly active and safe in heavily treated patients with T-cell lymphoma (PTCL) and cutaneous T-cell lymphoma (CTCL)

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Background: Our group has demonstrated that combinations of epigenetic modifiers produce potent synergy in pre-clinical models of PTCL and induce the expression of cancer testis antigen, suggesting a role in the addition of the immune-checkpoint inhibitor, pembrolizumab. Methods: This is a phase 1b study of pembrolizumab combined with pralatrexate alone (Arm A), with pralatrexate + decitabine (Arm B), or decitabine alone (Arm C) in patients with relapsed and refractory PTCL and CTCL. A standard 3+3 dose-escalation is applied in the triplet Arm (Arm B) while in the doublet Arms (A and C) de-escalation is applied in case of toxicity. Pharmacokinetic and pharmacodynamic studies are ongoing. Results: We treated a total of 12 patients with 4 patients in each Arm. All patients that received at least one dose of drug were evaluable for toxicity. There was a dose limiting toxicity (DLT) in each arm including prolonged grade 3 thrombocytopenia (Arm A), febrile neutropenia (Arm B), grade 3 hyponatremia, and rash (Arm C). There were no treatment-related deaths. Six patients out of 12 were evaluable for response at the time of this analysis. One patient achieved a complete remission, 2 had partial remission, 1 had stable disease, and 2 experienced progression of disease. Interestingly, all of the responses were seen in the triple combination of pralatrexate, decitabine, and pembrolizumab. Table summarizes the patient characteristics, toxicities, and response rates. Conclusions: These preliminary clinical data suggest that the integration of pembrolizumab on an epigenetic backbone is safe and demonstrates encouraging responses in patient with PTCL and CTCL. Clinical trial information: 03240211 . [Table: see text]

The anti-tumor activity of pralatrexate (PDX) correlates with the expression of RFC and DHFR mRNA in preclinical models of multiple myeloma

Multiple myeloma (MM) is the second most common hematologic malignancy. While major advances have been made in the disease, it is still incurable. Although antifolate-based drugs are not commonly used to treat myeloma, new generation analogs with distinct patterns of preclinical and clinical activity may offer an opportunity to identify new classes of potentially active drugs. Pralatrexate (PDX), which was approved for the treatment of relapsed or refractory peripheral T-cell lymphoma in 2009, may be one such drug. Pralatrexate exhibits a potency and pattern of activity distinct from its predecessors like methotrexate (MTX). We sought to understand the activity and mechanisms of resistance of multiple myeloma to these drugs, which could also offer potential strategies for selective use of the drug. We demonstrate that PDX and MTX both induce a significant decrease in cell viability in the low nanomolar range, with PDX exhibiting a more potent effect. We identified a series of myeloma cell lines exhibiting markedly different patterns of sensitivity to the drugs, with some lines frankly resistant, and others exquisitely sensitive. These differences were largely attributed to the basal RFC (Reduced Folate Carrier) mRNA expression levels. RFC mRNA expression correlated directly with rates of drug uptake, with the most sensitive lines exhibiting the most significant intracellular accumulation of pralatrexate. This mechanism explains the widely varying patterns of sensitivity and resistance to pralatrexate in multiple myeloma cell lines. These findings could have implications for this class of drugs and their role in the treatment of multiple myeloma.

The rapidly changing landscape in mature T-cell lymphoma (MTCL) biology and management

Historical advances in the care of patients with non-Hodgkin lymphoma (NHL) have been restricted largely to patients with B-cell lymphoma. The peripheral T-cell lymphomas (PTCLs), which are rare and heterogeneous in nature, have yet to experience the same degree of improvement in outcome over the past 20 to 30 years. It is estimated that there are approximately 80,000 and 14,000 cases, respectively, of NHL and Hodgkin lymphoma per year in the United States. As a subgroup of NHL, the PTCLs account for 6% to 10% of all cases of NHL, making them exceedingly rare. In addition, the World Health Organization 2017 classification describes 29 distinct subtypes of PTCL. This intrinsic diversity, coupled with its rarity, has stymied progress in the disease. In addition, most subtypes carry an inferior prognosis compared with their B-cell counterparts, an outcome largely attributed to the fact that most treatment paradigms for patients with PTCL have been derived from B-cell neoplasms, a radically different disease. In fact, the first drug ever approved for patients with PTCL was approved only a decade ago. The plethora of recent drug approvals in PTCL, coupled with a deeper understanding of the molecular pathogenesis of the disease, has stimulated the field to pursue new avenues of research that are now largely predicated on the development of novel, targeted small molecules, which include a host of epigenetic modifiers and biologics. There is an expectation these advances may begin to favorably challenge the chemotherapy paradigms that have been used in the T-cell malignancies.

Survival benefit in patients with peripheral T-cell lymphomas after treatments with novel therapies and clinical trials

The peripheral T-cell lymphomas (PTCL) are rare and heterogeneous diseases characterized by an unfavorable prognosis. Chemotherapy is standard upfront treatment in most patients, but responses are short-lived with few FDA-approved "novel" agents available. We sought to define the impact of these novel agents as single agents or in clinical trials on the outcomes of patients with PTCL. From January 1994 to May 2019, adult patients with PTCL who were managed at our institution were included in this analysis. In addition to patients with incomplete data, those diagnosed with large granular lymphocytic leukemia and cutaneous T-cell lymphoma (CTCL) except for transformed mycosis fungoides were excluded. Statistical analyses were performed using SAS version 9.4. There were 219 patients included in the analysis. The median age at diagnosis was 56 years (range, 18-90 years). First line therapies mostly consisted of combination chemotherapy (75%). There was a statistical difference among patients who received chemotherapy, novel agents alone and in chemotherapy-free combinations, other, and no treatment (P < .0001). In patients who were treated with second line chemotherapy, novel agents alone and in combination without chemotherapy, or other, there was a still a survival benefit favoring novel agents (P = .0417). In the third line, there was no statistical difference among the three groups (P = .569). All patients who received novel therapies and underwent autologous stem cell transplant (autoSCT) achieved a complete response (CR) and had a better survival compared with patients who underwent chemotherapy who had a 70% CR rate prior to autoSCT (P = .046). Exposure to FDA-approved novel agents, immunoepigenetic trials, and clinical trials in general was associated with an overall survival (OS) benefit (P = .003, P = .04, and P = .006, respectively). These data suggest that patients who receive novel agents have superior outcomes compared with patients without exposure to novel therapies who receive chemotherapy-predicated treatments.

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

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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.

An objective based model of published treatment options for relapsed or refractory (R/R) peripheral t-cell lymphoma (PTCL): An evidence-based decision-making approach

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Background: PTCL are rare diseases with a poor prognosis. Front line therapy achieves CR in 30% to 60% and OS of 25%. Patients with R/R disease have an even worse prognosis. There is no consensus on the management of R/R disease because evidence supporting most treatment approaches is modest. Many approaches are often not supported by literature, and categorizations regarding efficacy and toxicity without attention to details are ignored. Treatments that have achieved regulatory approval with stringent independent assessment of pathology and response are viewed as less established, or equivalent to smaller published experiences. In the effort to take a critical and comprehensive evidence-based approach to available standards in R/R PTCL we developed an objective scoring system for all types of studies published in the literature (eg randomized phase 3, case match control, phase 2, phase 1, case reports and small series) to aid decision-making based on an assessment of all the available data. Methods: An extensive review on PubMed of clinical trials published in literature for R/R PTCL was performed. A rigorous scoring system based on a survey from 100 authorities in the field to quantitate scientific impact of each study based was developed. These include: type of study (randomized phase 3, case match control analysis, phase 2 weighted based on number of PTCL patients [ > 100 vs < 100 patients], phase 1 with > 5 or < 5 PTCL patients enrolled, and retrospective); weighting for use of central pathology or response review; weighting for detailed study metrics (ORR, CR, DoR, PFS). The scoring system included a penalty for omission detail. The proposed scoring system was evaluated by a panel of experts. The scoring system was modified based on recommendations made by 2 or more panel members. Results: We identified 58 publications between 2004 and 2018. The scoring system spanned from 0 to 9. Only 12 of the 58 studies had a score above 5; 15 of 58 had a score between 1 - 5; remaining publications scored 0 - 1. Conclusions: Our analysis suggests practice patterns are based on studies with low priority scores, and underweight robust clinical experiences. This analysis aims to produce an evidenced based approach for R/R PTCL.

Response to A+CHP by CD30 expression in the ECHELON-2 trial

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Background: Brentuximab vedotin (BV) is an antibody-drug conjugate that targets CD30. The ECHELON-2 (E-2) study demonstrated significantly longer progression-free and overall survival with BV plus cyclophosphamide, doxorubicin, and prednisone (A+CHP) versus CHOP in frontline treatment of patients (pts) with CD30+ peripheral T-cell lymphoma (PTCL). Complete remission (CR) rate (A+CHP 68%; CHOP 56%) and objective response rate (ORR) (A+CHP 83%; CHOP 72%) were also significantly increased. Expression of CD30 is universal in systemic anaplastic large-cell lymphoma (sALCL) but variable among non-sALCL subtypes. As ORR is a direct measure of antitumor activity, we examined response to A+CHP by CD30 expression. Methods: Pts with CD30+ (≥10% by local review) PTCL were included in E-2. Eligible histologies included ALK+ sALCL (IPI ≥2), ALK− sALCL, PTCL-not otherwise specified (PTCL-NOS), angioimmunoblastic T-cell lymphoma (AITL), adult T-cell leukemia/lymphoma, enteropathy-associated T-cell lymphoma, and hepatosplenic T-cell lymphoma. We analyzed the relationship between CD30 expression (IHC Ber H2 antibody) above and below the median (median CD30=18% PTCL-NOS; 25% AITL) and CR rate, ORR, and duration of CR (DOCR) in pts with AITL and PTCL-NOS treated with A+CHP. Results: Most (26/29, 90%) AITL pts had CD30 expression between 10% and 30%. PTCL-NOS pts were more evenly distributed across levels of CD30 expression ranging from 10% to 100%. CD30 levels were neither predictive of response (Table) nor significantly associated with DOCR in pts with AITL (P=0.30) or PTCL-NOS (P=0.90) (log-rank test). Response by CD30 expression. Clinical trial information: NCT01777152. Conclusions: CD30 expression above vs below median (or at 10%) did not predict response to A+CHP in E-2 non-ALCL subtypes, as responses were seen across CD30 levels. This may be due to intra- and inter-tumoral heterogeneity of CD30 expression, limitations of IHC, the nature of CD30 on the cell surface, and multiple mechanisms of action of BV. Further evaluation of the expression-response relationship in PTCL pts with CD30 <10% is warranted.[Table: see text]

Survival outcomes of patients with peripheral T-cell lymphomas (PTCL) treated with chemotherapy and/or novel agents: The Columbia University experience

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Background: CHOP-based regimens have been considered the standard of care for PTCL despite disappointing results. Several lines of evidence, including the regulatory approval of novel drugs since 2009, raise the question as to whether these drugs are changing the natural history of relapsed PTCL. Recent molecular insights into the pathogenesis of PTCL, especially in angioimmunoblastic T-cell lymphoma (AITL), have revealed a number of genetic lesions that might portend a unique vulnerability to select agents, such as histone deacetylase inhibitors (HDACi). Methods: This is a retrospective study of patients with PTCL who were seen and treated between 1994 and 2018. Kaplan-Meier curves for overall survival were generated and compared based on the log-rank test. Cox proportional hazard models were used to investigate the association by adjusting for age, gender, subtype, prognostic score and type of treatment. The analysis was done in SAS version 9.4. A p-value < 0.05 was considered statistically significant. Results: At Columbia University Medical Center, a total of 186 patients with PTCL were identified. Excluding patients with incomplete data, 168 patients were analyzed. The median overall survival was 7.5 months (95% CI 5.6-8.9) for the whole study group. Cox modeling adjusted for the aforementioned variables found little impact from the novel agents on the natural history of the disease. In particular, among patients with AITL, no survival benefit was associated with any HDACi. In addition, these data demonstrated that patients with adult T-cell leukemia lymphoma (ATLL) had a better overall survival compared to other subgroups, p = 0.0097. Conclusions: These data are concordant with other large experiences noting the poor prognosis of patients with PTCL, and in particular, those with relapsed disease. The lack of impact of HDACi on the natural history of AITL raises issues about the role of these drugs in this disease. We will present a variety of subanalyses to identify prognostic factors in PTCL. [Table: see text]

ENGINE: Phase III randomized study of enzastaurin/R-CHOP versus placebo/R-CHOP in frontline high-risk diffuse large B-cell lymphoma patients with novel genomic biomarker DGM1

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Background: Progress in genome technology allows analysis of previously completed trials to identify patients subgroups potentially benefiting from therapy. Enzastaurin is a potent inhibitor of protein kinase C beta (PKC- b) and suppresses the phosphoinositide 3-kinase (PI3K)/AKT pathway. The safety and efficacy of Enzastaurin has been tested in more than 60 clinical trials including 2 major studies in DLBCL: (1) PRELUDE (A phase III maintenance trial of Enzastaurin vs Placebo, N=758) ( Crump, 2016), and (2) S028 (A randomized phase II study of Enzastaurin/R-CHOP vs R-CHOP in frontline intermediate/high-risk DLBCL, N=101) ( Hainsworth, 2016). DNA samples extracted from blood of patients from PRELUDE were retrospectively genotyped using whole genome SNP arrays. From the genome wide screening a novel genetic biomarker, DGM1, was identified showing high correlation with response to Enzastaurin treatment ( Luo, ASH 2018). Importantly, these findings were replicated in the phase II S028 study. In the S028 study the hazard ratio (HR) for OS in high-risk (IPI ≥ 3) DGM1 positive (+) patients who received Enzastaurin/R-CHOP was 0.28 (0.1-0.81) when compared to subjects who received R-CHOP, a benefit favoring Enzastaurin (p=0.018). These data suggest that addition of Enzastaurin to R-CHOP may significantly improve outcome in frontline high-risk DGM1 (+) DLBCL. The ENGINE study was initiated to validate this finding in a prospective study. Methods: Adult patients must have untreated CD20+ DLBCL, IPI ≥ 3. Patients are randomized 1:1 to Enzastaurin/R-CHOP or Placebo/R-CHOP for 6 cycles during combination phase. Each subject’s treatment assignment will be unblinded after response assessment at the end of the combination phase. Subjects randomized to the investigational arm who have a complete or partial response will have the option to continue in the single agent phase to receive Enzastaurin for up to 2 additional years. The study intends to enroll approximately 235 patients with primary endpoint of OS in DGM1 (+) patients. The study is ongoing with 51 sites open in the US and China. As of 22 Jan 2019, 70 patients have been randomized. Clinical trial information: NCT03263026.

Effect of epigenetic modifier-based combinations on efficacy in patients with peripheral T-cell lymphoma (PTCL): Deciphering impact of mutations in epigenetic operations on response

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Background: Recurring mutations in epigenetic functions in PTCL, coupled with marked activity of epigenetic drugs, raises a question regarding whether these mutations might portend greater vulnerability to one drug over another. For example, do mutations in genes governing DNA methylation suggest these patients might benefit from a hypomethylating (HMA) agent? Preclinical data from our group suggests marked synergism between histone deacetylase inhibitors (HDACi) and HMA, as well as HDACi and pralatrexate (PDX), irrespective of mutations in epigenetic genes. Phase 1 studies (romidepsin [R] plus PDX or R plus 5-azacytidine [Aza]) are completed, and the Phase 2 studies are near completion. This clinical trial scenario affords a unique opportunity to decipher the impact of a HMA on response as a function of TET2, IDH2, DNMT3 and other mutations in PTCL. Methods: Patients with R/R lymphoma were eligible for the phase 1, whereas the phase 2 only enrolled patients with PTCL, either R/R or treatment-naïve individuals. Exploratory endpoints included next generation sequencing (NGS) and methylation arrays. Results: In toto, 89 patients have been enrolled on both trials across all histology’s, 58 have PTCL. NGS and efficacy data is available for the majority of patients, with some from the PDX + R study in process. The ORR among the PTCL patients for PDX+R and Aza+R has been 71% and 73% respectively. Eight of 9 angioimmunoblastic TCL patients responded. Among those with TET2 mutations, 7 of 8 responded to the Aza based treatment, while only 3 of 6 (50%) who were TET2 negative responded. Similarly, of 3 patients with DNMT3 treated with Aza based therapy, all 3 responded. Remarkably one patient with a TET2 mutation experienced progression to PDX+R, and CR to Aza+R. Among the PTCL patients treated with Aza, the global demethylation score (GDMS) demonstrated marked demethylation among all patients, with no correlation between the score and likelihood of response. Conclusions: We will share the completely annotated analysis correlating clinical metrics to the spectrum of epigenetic mutations and GDMS and across all histology’s and treatments. Clinical trial information: NCT01998035; NCT01947140.

Imidazole Ketone Erastin Induces Ferroptosis and Slows Tumor Growth in a Mouse Lymphoma Model

Ferroptosis is a form of regulated cell death that can be induced by inhibition of the cystine-glutamate antiporter, system xc-. Among the existing system xc- inhibitors, imidazole ketone erastin (IKE) is a potent, metabolically stable inhibitor of system xc- and inducer of ferroptosis potentially suitable for in vivo applications. We investigated the pharmacokinetic and pharmacodynamic features of IKE in a diffuse large B cell lymphoma (DLBCL) xenograft model and demonstrated that IKE exerted an antitumor effect by inhibiting system xc-, leading to glutathione depletion, lipid peroxidation, and the induction of ferroptosis biomarkers both in vitro and in vivo. Using untargeted lipidomics and qPCR, we identified distinct features of lipid metabolism in IKE-induced ferroptosis. In addition, biodegradable polyethylene glycol-poly(lactic-co-glycolic acid) nanoparticles were employed to aid in IKE delivery and exhibited reduced toxicity compared with free IKE in a DLBCL xenograft model.

IL-22-Independent Protection from Colitis in the Absence of Nkx2.3 Transcription Factor in Mice

The transcription factor Nkx2.3 regulates the vascular specification of Peyer patches in mice through determining endothelial addressin preference and may function as a susceptibility factor in inflammatory bowel diseases in humans. We wished to analyze the role of Nkx2.3 in colonic solitary intestinal lymphoid tissue composition and in colitis pathogenesis. We studied the colonic solitary intestinal lymphoid tissue of Nkx2.3-deficient mice with immunofluorescence and flow cytometry. Colitis was induced in mice using 2.5% dextran sodium sulfate, and severity was assessed with histology, flow cytometry, and quantitative PCR. We found that the lack of Nkx2.3 impairs maturation of isolated lymphoid follicles and attenuates dextran sodium sulfate-induced colitis independent of endothelial absence of mucosal addressin cell-adhesion molecule-1 (MAdCAM-1), which was also coupled with enhanced colonic epithelial regeneration. Although we observed increased numbers of group 3 innate lymphoid cells and Th17 cells and enhanced transcription of IL-22, Ab-mediated neutralization of IL-22 did not abolish the protection from colitis in Nkx2.3-deficient mice. Nkx2.3-/- hematopoietic cells could not rescue wild-type mice from colitis. Using LacZ-Nkx2.3 reporter mice, we found that Nkx2.3 expression was restricted to VAP-1+ myofibroblast-like pericryptal cells. These results hint at a previously unknown stromal role of Nkx2.3 as driver of colitis and indicate that Nkx2.3+ stromal cells play a role in epithelial cell homeostasis.

Randomized Phase III Study of Alisertib or Investigator's Choice (Selected Single Agent) in Patients With Relapsed or Refractory Peripheral T-Cell Lymphoma

PURPOSE

The aim of this open-label, first-in-setting, randomized phase III trial was to evaluate the efficacy of alisertib, an investigational Aurora A kinase inhibitor, in patients with relapsed/refractory peripheral T-cell lymphoma (PTCL).

PATIENTS AND METHODS

Adult patients with relapsed/refractory PTCL—one or more prior therapy—were randomly assigned 1:1 to receive oral alisertib 50 mg two times per day (days 1 to 7; 21-day cycle) or investigator-selected single-agent comparator, including intravenous pralatrexate 30 mg/m² (once per week for 6 weeks; 7-week cycle), or intravenous gemcitabine 1,000 mg/m² or intravenous romidepsin 14 mg/m² (days 1, 8, and 15; 28-day cycle). Tumor tissue (disease subtype) and imaging were assessed by independent central review. Primary outcomes were overall response rate and progression-free survival (PFS). Two interim analyses and one final analysis were planned.

RESULTS

Between May 2012 and October 2014, 271 patients were randomly assigned (alisertib, n = 138; comparator, n = 133). Enrollment was stopped early on the recommendation of the independent data monitoring committee as a result of the low probability of alisertib achieving PFS superiority with full enrollment. Centrally assessed overall response rate was 33% for alisertib and 45% for the comparator arm (odds ratio, 0.60; 95% CI, 0.33 to 1.08). Median PFS was 115 days for alisertib and 104 days for the comparator arm (hazard ratio, 0.87; 95% CI, 0.637 to 1.178). The most common adverse events were anemia (53% of alisertib-treated patients v 34% of comparator-treated patients) and neutropenia (47% v 31%, respectively). A lower percentage of patients who received alisertib (9%) compared with the comparator (14%) experienced events that led to study drug discontinuation. Of 26 on-study deaths, five were considered treatment related (alisertib, n = 3 of 11; comparator, n = 2 of 15). Two-year overall survival was 35% for each arm.

CONCLUSION

In patients with relapsed/refractory PTCL, alisertib was not statistically significantly superior to the comparator arm.

Brentuximab vedotin with chemotherapy for CD30-positive peripheral T-cell lymphoma (ECHELON-2): a global, double-blind, randomised, phase 3 trial

BACKGROUND

Based on the encouraging activity and manageable safety profile observed in a phase 1 study, the ECHELON-2 trial was initiated to compare the efficacy and safety of brentuximab vedotin, cyclophosphamide, doxorubicin, and prednisone (A+CHP) versus cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) for the treatment of CD30-positive peripheral T-cell lymphomas.

METHODS

ECHELON-2 is a double-blind, double-dummy, randomised, placebo-controlled, active-comparator phase 3 study. Eligible adults from 132 sites in 17 countries with previously untreated CD30-positive peripheral T-cell lymphomas (targeting 75% with systemic anaplastic large cell lymphoma) were randomly assigned 1:1 to receive either A+CHP or CHOP for six or eight 21-day cycles. Randomisation was stratified by histological subtype according to local pathology assessment and by international prognostic index score. All patients received cyclophosphamide 750 mg/m² and doxorubicin 50 mg/m² on day 1 of each cycle intravenously and prednisone 100 mg once daily on days 1 to 5 of each cycle orally, followed by either brentuximab vedotin 1·8 mg/kg and a placebo form of vincristine intravenously (A+CHP group) or vincristine 1·4 mg/m² and a placebo form of brentuximab vedotin intravenously (CHOP group) on day 1 of each cycle. The primary endpoint, progression-free survival according to blinded independent central review, was analysed by intent-to-treat. This trial is registered with ClinicalTrials.gov, number NCT01777152.

FINDINGS

Between Jan 24, 2013, and Nov 7, 2016, 601 patients assessed for eligibility, of whom 452 patients were enrolled and 226 were randomly assigned to both the A+CHP group and the CHOP group. Median progression-free survival was 48·2 months (95% CI 35·2-not evaluable) in the A+CHP group and 20·8 months (12·7-47·6) in the CHOP group (hazard ratio 0·71 [95% CI 0·54-0·93], p=0·0110). Adverse events, including incidence and severity of febrile neutropenia (41 [18%] patients in the A+CHP group and 33 [15%] in the CHOP group) and peripheral neuropathy (117 [52%] in the A+CHP group and 124 [55%] in the CHOP group), were similar between groups. Fatal adverse events occurred in seven (3%) patients in the A+CHP group and nine (4%) in the CHOP group.

INTERPRETATION

Front-line treatment with A+CHP is superior to CHOP for patients with CD30-positive peripheral T-cell lymphomas as shown by a significant improvement in progression-free survival and overall survival with a manageable safety profile.

FUNDING

Seattle Genetics Inc, Millennium Pharmaceuticals Inc, a wholly owned subsidiary of Takeda Pharmacuetical Company Limited, and National Institutes of Health National Cancer Institute Cancer Center.

Strategy for Assessing New Drug Value in Orphan Diseases: An International Case Match Control Analysis of the PROPEL Study

Background

Although randomized studies are designed to assess overall survival (OS) benefit, the conduct of regulatory studies in patients with orphan diseases can be timely and costly without offering the same commercial return on the investment. The peripheral T-cell lymphomas (PTCL) represent a rare group of heterogeneous lymphoid malignancies with very poor prognosis. PROPEL was a pivotal phase II study that led to the accelerated approval of pralatrexate for patients with relapsed or refractory PTCL.

Methods

An international database of 859 patients was assembled from four institutions with an interest in PTCL, of which 386 were considered eligible for matching against the PROPEL criteria. Using a rigorous propensity score matching algorithm, a unique 1:1 case match of 80 patients was performed.

Results

The analysis demonstrated an OS benefit for the PROPEL population with a median OS of 4.07 and 15.24 months (hazard ratio = 0.432, 95% confidence interval = 0.298 to 0.626), respectively, for the control and PROPEL populations. Highly statistically significant improvements in OS were noted for the PROPEL population about the subtype of PTCL (save anaplastic large cell lymphoma) and all age groups, including the elderly (>65 years of age). For patients on PROPEL, there was a statistically significant prolongation in progression free survival compared with the line of prior therapy, including those with refractory disease.

Conclusion

In the context of this case-match-control study, patients treated on PROPEL experienced an OS advantage compared with an international database of historical controls. This information can help inform critical decision-making regarding clinical studies in PTCL.

Brentuximab vedotin plus bendamustine in relapsed or refractory Hodgkin's lymphoma: an international, multicentre, single-arm, phase 1-2 trial

Background:

The major objective of this study was to explore the safety and clinical activity of Brentuximab vedotin (Bv) and bendamustine in combination in patients with relapsed or refractory Hodgkin Lymphoma. Bv produces high response rates and durable progression-free survival (PFS) in CD30-expressing lymphomas and is approved for the treatment of relapsed Hodgkin lymphoma (HL) and relapsed ALCL. Bendamustine (B) is active agent across the lymphoproliferative malignancies, though the PFS among patients with HL and PTCL is modest.

Methods:

This was an international, multicenter, single-arm, Phase 1–2 study of BvB in patients with relapsed or refractory HL and ALCL. Eligible patients were required to have relapsed/refractory CD30+ biopsy proven HL or ALCL and an ECOG Performance Status ≤2. In the Phase 1, HL patients were deemed eligible if they developed progressive disease following or after declining ASCT, or had at least 2 prior multi-agent chemotherapy regimens. In the Phase 2, patients with HL were eligible if they had relapsed or refractory disease after one line of therapy. Eligible ALCL patients were required to have relapsed after at least one prior multi-agent chemotherapy regimen and if they were not eligible for or have declined ASCT. The primary objective of the Phase I portion of this study was to identify the maximum tolerated dose (MTD) and dose limiting toxicity (DLT). The primary endpoint of the Phase 2 portion was to determine the overall response rate (ORR; complete response [CR] plus partial response [PR])) based on an intention to treat analysis (ITT). Secondary objectives of Phase 1–2 included assessing for duration of response, progression free survival and overall survival. Response was evaluated using International Harmonization Project Group 2007 Revised Response Criteria. Bv was escalated from 1.2mg/kg Day 1, and B from 70mg/m2 Days 1 and 2 every 21 days until the MTD or recommended phase 2 dose (RP2D) was reached. The study is ongoing but no longer recruiting patients. This trial is registered with ClinicalTrials.gov number NCT01657331.

Findings:

65 patients (only 1 ALCL) were treated, 28 on the Phase 1 and 37 on the phase 2. While the MTD of the combination was not reached, the single agent MTD of Bv (1.8mg/kg Day 1) and RP2D of B (90mg/m2 Days 1 and 2) were identified as the RP2D of the combination. Patients were heavily treated, 65% (42 of 65) had an autologous or allogeneic stem cell transplant or both. The Phase 1 revealed modest toxicity. The major Grade 3/4 toxicities included Grade 3 lung infection in 5 (14%) patients in the Phase 2, and Grade 3/4 neutropenia in 13 (24%) patients across the Phase 1 and 2. The Phase 1 and 2 overall response rates (ORR) were 61% and 78% respectively, with 43% (16 of 27) patients treated in the Phase 2 attaining a complete remission (CR). In the Phase 2, the median PFS has not been reached and duration of response (DOR) was 3.4 months. There was a total of 23 deaths with 21 due to progression of disease, 2 occurring after being transplanted, and none of which were treatment related.

Interpretation:

This demonstrates that BvB might be an effective salvage regimen for patients with HL, with a favorable safety profile.

Funding:

Seattle Genetics, The Lymphoma Research Fund of Columbia University and National Center for Advancing Translational Sciences, National Institutes of Health, through Grant Number UL1TR001873 provided support for this investigator initiated sponsored trial. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.

Abstract 2709: Evaluation of CD37 expression and binding of AGS67E, an antibody-drug conjugate (ADC) against CD37, on white blood cells (WBCs) collected from phase I non-Hodgkin lymphoma (NHL) patients

AGS67E is an antibody drug conjugate (ADC) against CD37 conjugated to monomethyl auristatin E (MMAE). CD37 is expressed on normal WBCs, but is also highly expressed in NHL, CLL and AML (Pereira et al., 2015). A phase I study is currently evaluating the safety, PK and anti-cancer activity of AGS67E with or without growth factor (GF) in subjects with relapsed/refractory NHL. To assess CD37 expression on WBCs, binding of AGS67E, and potential pharmacodynamic effects, samples from subjects were collected at pre-dose, D2, D8, and D15 and analyzed by flow cytometry. CD37 expression on subject tumor samples was also evaluated by immunohistochemistry (IHC). Our results demonstrated that CD37 was highly expressed in tumor samples and that AGS67E binds to WBCs causing down-regulation of CD37, achieving saturation of binding at 24 hours post-treatment (earliest time measured) at or above 0.9 mg/kg. A dose-dependent decrease in the number of all cell types examined was observed with a nadir occurring at D8, with partial or full recovery at D15, except for neutrophils. NK and T cell counts appeared to be least impacted while neutrophils were most affected. B cell counts were extremely low pre-dose for some patients, presumably from prior therapies. In patients treated at 0.9 mg/kg and higher without GF, recovery of neutrophils was delayed beyond D15. At doses of 1.2 mg/kg and higher, use of GF resulted in a significant recovery of neutrophils by D15. The extent of cell count decreases did not correlate to the proportion of cells expressing CD37. For example, decreases in NK cells, monocytes, and, in some cases, T cells, were much greater than the proportion of cells expressing CD37. Furthermore, mature WBCs are unlikely to be affected by AGS67E. This raises the possibility that the main effect of AGS67E may be on rapidly growing precursor cells and that cells with low, or no, CD37 expression may be impacted by the membrane permeable MMAE through a by-stander effect. The effect of AGS67E on neutrophils was investigated in an in vitro assay where hematopoietic stem cells were differentiated into neutrophils. Using this method, we showed that when AGS67C antibody was conjugated to a non-cleavable, membrane impermeable auristatin (mcMMAF) less cytotoxicity to differentiating neutrophils was observed compared to AGS67E. Previously, we have shown that neutrophils secrete proteases that can liberate MMAE from ADCs (Zhao et al, 2016). These results suggest that AGS67E contributes to neutropenia through a by-stander effect, in addition to the CD37-mediated internalization of the ADC. In conclusion, the results showed that AGS67E bound to its target CD37, modulated its expression, achieved saturation of binding at doses at or above 0.9 mg/kg, and reversibly depleted WBCs, with the exception of neutrophils for which GF administration appeared to significantly improve recovery rate.

Citation Format: Sher Karki, Hector Avina, Jacqueline Lackey, Ahmed Sawas, Kerry J. Savage, Raymond Perez, Ranjana Advani, Jasmine Zain, Owen A. O'Connor, Sara Gulesserian, Hui Zhao, Peng Yang, Karen Morrison, Leonard Reyno, Fernando Donate. Evaluation of CD37 expression and binding of AGS67E, an antibody-drug conjugate (ADC) against CD37, on white blood cells (WBCs) collected from phase I non-Hodgkin lymphoma (NHL) patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2709. doi:10.1158/1538-7445.AM2017-2709

Mechanisms of Acquired Drug Resistance to the HDAC6 Selective Inhibitor Ricolinostat Reveals Rational Drug-Drug Combination with Ibrutinib

Purpose: Pan-class I/II histone deacetylase (HDAC) inhibitors are effective treatments for select lymphomas. Isoform-selective HDAC inhibitors are emerging as potentially more targeted agents. ACY-1215 (ricolinostat) is a first-in-class selective HDAC6 inhibitor. To better understand the discrete function of HDAC6 and its role in lymphoma, we developed a lymphoma cell line resistant to ACY-1215.Experimental Design: The diffuse large B-cell lymphoma cell line OCI-Ly10 was exposed to increasing concentrations of ACY-1215 over an extended period of time, leading to the development of a resistant cell line. Gene expression profiling (GEP) was performed to investigate differentially expressed genes. Combination studies of ACY-1215 and ibrutinib were performed in cell lines, primary human lymphoma tissue, and a xenograft mouse model.Results: Systematic incremental increases in drug exposure led to the development of distinct resistant cell lines with IC50 values 10- to 20-fold greater than that for parental lines. GEP revealed upregulation of MAPK10, HELIOS, HDAC9, and FYN, as well as downregulation of SH3BP5 and LCK. Gene-set enrichment analysis (GSEA) revealed modulation of the BTK pathway. Ibrutinib was found to be synergistic with ACY-1215 in cell lines as well as in 3 primary patient samples of lymphoma. In vivo confirmation of antitumor synergy was demonstrated with a xenograft of DLBCL.Conclusions: The development of this ACY-1215-resistant cell line has provided valuable insights into the mechanistic role of HDAC6 in lymphoma and offered a novel method to identify rational synergistic drug combinations. Translation of these findings to the clinic is underway. Clin Cancer Res; 23(12); 3084-96. ©2016 AACR.

Innovative approach to determine overall survival (OS) benefit for orphan diseases using case match control analyses (CMCA): The PROPEL experience of pralatrexate in patients with relapsed/refractory (R/R) peripheral T-cell lymphoma (PTCL)

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Background: The challenges in conducting randomized studies in orphan diseases poses limitations on our ability to identify the most promising treatments. Randomized studies in this setting can take protracted periods of time to complete, can be very expensive while not offering the promise of significant commercial return, and could become irrelevant as the pace of scientific advancement continues. The majority of drugs approved in this setting are often approved on surrogate end-points like progression free survival (PFS) or complete response (CR) rates in single arm studies. CMCA are statistically stronger than single arm studies, and can be highly informative in this setting. Methods: We established an integrated international database of patients with R/R PTCL to clarify the OS advantage of pralatrexate using original data from the PROPEL study, an international, multicenter phase II study in patients with R/R PTCL. The propensity score was used to match cases and controls. Cases were matched based on histology, number of previous treatments received, age at diagnosis and sex. Results: With 1:1 ratio match, we identified 83 cases and 83 controls. In total, 83 patients out of 109 treated on the PROPEL study were successfully matched. OS was plotted for each of the two study populations. The survival curves for the control population were found to be nearly identical to that reported for this population from other datasets. The overall survival was 4.04 months (95% CI 2.83, 5.78), which is consistent with historical controls describing this population. The median OS in for the pralatrexate treated cohort in this analysis was 16.6 months (95% CI: 11.99-25.56). The OS was a highly statistically significant difference between these two populations, with a hazard ratio of 0.426 (95% CI: 0.296-0/61). This difference held up for each of the major histologic subsets, including PTCL-NO and angioimmunoblastic PTCL. Conclusions: This approach can be used to better understand how new drugs in orphan diseases perform in heterogeneous patient populations. Clinical trial information: NCT00364923.

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.

Brentuximab vedotin, an antibody-drug conjugate, in patients with CD30-positive haematologic malignancies and hepatic or renal impairment

Aims

Brentuximab vedotin, an antibody–drug conjugate (ADC), selectively delivers the microtubule‐disrupting agent monomethyl auristatin E (MMAE) into CD30‐expressing cells. The pharmacokinetics of brentuximab vedotin have been characterized in patients with CD30‐positive haematologic malignancies. The primary objective of this phase 1 open label evaluation was to assess the pharmacokinetics of brentuximab vedotin in patients with hepatic or renal impairment.

Methods

Systemic exposures were evaluated following intravenous administration of 1.2 mg kg^–1 brentuximab vedotin in patients with CD30‐positive haematologic malignancies and hepatic (n = 7) or renal (n = 10) impairment and compared with those of unimpaired patients (n = 8) who received 1.2 mg kg^–1 brentuximab vedotin in another arm of the study.

Results

For any hepatic impairment, the ratios of geometric means (90% confidence interval) for AUC(0,∞) were 0.67 (0.48, 0.93) for ADC and 2.29 (1.27, 4.12) for MMAE. Mild or moderate renal impairment caused no apparent change in ADC or MMAE exposures. Severe renal impairment (creatinine clearance <30 ml min^–1; n = 3) decreased ADC exposures (0.71 [0.54, 0.94]) and increased MMAE exposures (1.90 [0.85, 4.21]). No consistent pattern of specific adverse events was evident, but analysis of the safety data was confounded by the patients' poor baseline conditions. Five patients died due to adverse events considered unrelated to brentuximab vedotin. All had substantial comorbidities and most had poor baseline performance status.

Conclusions

Hepatic impairment and severe renal impairment may cause decreases in brentuximab vedotin ADC exposures and increases in MMAE exposures.