Immunochemotherapy plus lenalidomide for high-risk mantle cell lymphoma with measurable residual disease evaluation

Chemoimmunotherapy followed by consolidative high-dose therapy with autologous stem cell rescue was a standard upfront treatment for fit patients with mantle cell lymphoma (MCL) in first remission; however, treatment paradigms are evolving in the era of novel therapies. Lenalidomide is an immunomodulatory agent with known efficacy in treating MCL. We conducted a single-center, investigator-initiated, phase II study of immunochemotherapy incorporating lenalidomide, without autologous stem cell transplant consolidation, enriching for patients with high-risk MCL (clinicaltrials gov. Identifier: NCT02633137). Patients received four cycles of lenalidomide-R-CHOP, two cycles of R-HiDAC, and six cycles of R-lenalidomide. The primary endpoint was rate of 3-year progression-free survival. We measured measurable residual disease (MRD) using a next-generation sequencing-based assay after each phase of treatment and at 6 months following end-oftreatment. We enrolled 49 patients of which 47 were response evaluable. By intent-to-treat, rates of overall and complete response were equivalent at 88% (43/49), one patient with stable disease, and two patients had disease progression during study; 3-year progression-free survival was 63% (primary endpoint not met) and differed by TP53 status (78% wild-type vs. 38% ALT; P=0.043). MRD status was prognostic and predicted long-term outcomes following R-HiDAC and at 6 months following end-of-treatment. In a high-dose therapy-sparing, intensive approach, we achieved favorable outcomes in TP53- wild-type MCL, including high-risk cases. We confirmed that sequential MRD assessment is a powerful prognostic tool in patients with MCL.

Mosunetuzumab with polatuzumab vedotin in relapsed or refractory aggressive large B cell lymphoma: a phase 1b/2 trial

Relapsed/refractory aggressive large B cell lymphoma (LBCL) remains an area of unmet need. Here we report the primary analysis of a phase 1b/2 trial of outpatient mosunetuzumab (a CD20xCD3 T-cell-engaging bispecific antibody) plus polatuzumab vedotin (an anti-CD79B antibody-drug conjugate) in relapsed/refractory LBCL. The phase 2 component is a single arm of an ongoing multi-arm trial. The primary endpoint during dose expansion was independent review committee (IRC)-assessed best overall response rate. Secondary endpoints included investigator-assessed overall response rate, complete response, duration of response, progression-free survival and overall survival. At data cutoff, 120 patients were enrolled (22 dose escalation, 98 dose expansion). The primary endpoint was met during dose expansion, with IRC-assessed best overall response rate and complete response rates of 59.2% (58/98; 95% confidence interval (CI): 48.8-69.0) and 45.9% (45/98; 95% CI: 35.8-56.3), respectively (median follow-up, 23.9 months). Median duration of complete was not reached (95% CI: 20.5-not estimable (NE)). Median progression-free survival was 11.4 months (95% CI: 6.2-18.7). Median overall survival was 23.3 months (95% CI: 14.8-NE). Across dose escalation and expansion, the most common grade 3 or higher adverse events were neutropenia (25.0%, 30/120) and fatigue (6.7%, 8/120). Any-grade cytokine release syndrome occurred in 16.7% of patients. These data demonstrate that mosunetuzumab plus polatuzumab vedotin has a favorable safety profile with highly durable responses suitable as second-line therapy in transplant-ineligible relapsed/refractory LBCL. ClinicalTrials.gov identifier: NCT03671018 .

Enhanced clinical assessment of hematologic malignancies through routine paired tumor and normal sequencing

Genomic profiling of hematologic malignancies has augmented our understanding of variants that contribute to disease pathogenesis and supported development of prognostic models that inform disease management in the clinic. Tumor only sequencing assays are limited in their ability to identify definitive somatic variants, which can lead to ambiguity in clinical reporting and patient management. Here, we describe the MSK-IMPACT Heme cohort, a comprehensive data set of somatic alterations from paired tumor and normal DNA using a hybridization capture-based next generation sequencing platform. We highlight patterns of mutations, copy number alterations, and mutation signatures in a broad set of myeloid and lymphoid neoplasms. We also demonstrate the power of appropriate matching to make definitive somatic calls, including in patients who have undergone allogeneic stem cell transplant. We expect that this resource will further spur research into the pathobiology and clinical utility of clinical sequencing for patients with hematologic neoplasms.

Retrospective characterization of nodal marginal zone lymphoma

Nodal marginal zone lymphoma (NMZL) is a rare non-Hodgkin B-cell lymphoma that has historically been difficult to define, though is now formally recognized by the World Health Organization Classification. To better characterize the clinical outcomes of patients with NMZL, we reviewed a sequential cohort of 187 patients with NMZL to describe baseline characteristics, survival outcomes, and time-to-event data. Initial management strategies were classified into five categories: observation, radiation, anti-CD20 monoclonal antibody therapy, chemoimmunotherapy, or other. Baseline Follicular Lymphoma International Prognostic Index scores were calculated to evaluate prognosis. A total of 187 patients were analyzed. The five-year overall survival was 91% (95% confidence interval [CI], 87-95), with a median follow-up time of 71 months (range, 8-253) among survivors. A total of 139 patients received active treatment at any point, with a median follow-up time of 56 months (range, 13-253) among survivors who were never treated. The probability of remaining untreated at five years was 25% (95% CI, 19-33). For those initially observed, the median time to active treatment was 72 months (95% CI, 49-not reached). For those who received at least one active treatment, the cumulative incidence of receiving a second active treatment at 60 months was 37%. Transformation to large B-cell lymphoma was rare, with a cumulative incidence of 15% at 10 years. In summary, our series is a large cohort of uniformly diagnosed NMZL with detailed analyses of survival and time to event analyses. We showed that NMZL commonly presents as an indolent lymphoma for which initial observation is often a reasonable strategy.

TP53 mutations identify high-risk events for peripheral T-cell lymphoma treated with CHOP-based chemotherapy

Nodal peripheral T-cell lymphomas (PTCL), the most common PTCLs, are generally treated with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP)-based curative-intent chemotherapy. Recent molecular data have assisted in prognosticating these PTCLs, but most reports lack detailed baseline clinical characteristics and treatment courses. We retrospectively evaluated cases of PTCL treated with CHOP-based chemotherapy that had tumors sequenced by the Memorial Sloan Kettering Integrated Mutational Profiling of Actionable Cancer Targets next-generation sequencing panel to identify variables correlating with inferior survival. We identified 132 patients who met these criteria. Clinical factors correlating with an increased risk of progression (by multivariate analysis) included advanced-stage disease and bone marrow involvement. The only somatic genetic aberrancies correlating with inferior progression-free survival (PFS) were TP53 mutations and TP53/17p deletions. PFS remained inferior when stratifying by TP53 mutation status, with a median PFS of 4.5 months for PTCL with a TP53 mutation (n = 21) vs 10.5 months for PTCL without a TP53 mutation (n = 111). No TP53 aberrancy correlated with inferior overall survival (OS). Although rare (n = 9), CDKN2A-deleted PTCL correlated with inferior OS, with a median of 17.6 months vs 56.7 months for patients without CDKN2A deletions. This retrospective study suggests that patients with PTCL with TP53 mutations experience inferior PFS when treated with curative-intent chemotherapy, warranting prospective confirmation.

Dual targeting of CD19 and CD22 with bicistronic CAR-T cells in patients with relapsed/refractory large B-cell lymphoma

Relapse after CD19-directed chimeric antigen receptor T-cell (CAR-T) therapy for large B-cell lymphoma (LBCL) is commonly ascribed to antigen loss or CAR-T exhaustion. Multiantigen targeting and programmed cell death protein-1 blockade are rational approaches to prevent relapse. Here, we test CD19/22 dual-targeting CAR-T (AUTO3) plus pembrolizumab in relapsed/refractory LBCL (NCT03289455). End points include toxicity (primary) and response rates (secondary). Fifty-two patients received AUTO3 and 48/52 received pembrolizumab. Median age was 59 years (range, 27-83), 46/52 had stage III/ IV disease and median follow-up was 21.6 months. AUTO3 was safe; grade 1-2 and grade 3 cytokine release syndrome affected 18/52 (34.6%) and 1/52 (1.9%) patients, neurotoxicity arose in 4 patients (2/4, grade 3-4), and hemophagocytic lymphohistiocytosis affected 2 patients. Outpatient administration was tested in 20 patients, saving a median of 14 hospital days per patient. Overall response rates were 66% (48.9%, complete response [CR]; 17%, partial response). Median duration of remission (DOR) for CR patients was not reached and for all responding patients was 8.3 months (95% confidence interval [CI]: 3.0-not evaluable). 54.4% (CI: 32.8-71.7) of CR patients and 42.6% of all responding patients were projected to remain progression-free at ≥12 months. AUTO3 ± pembrolizumab for relapsed/refractory LBCL was safe and delivered durable remissions in 54.4% of complete responders, associated with robust CAR-T expansion. Neither dual-targeting CAR-T nor pembrolizumab prevented relapse in a significant proportion of patients, and future developments include next-generation-AUTO3, engineered for superior expansion in vivo, and selection of CAR binders active at low antigen densities.

Vitamin D Insufficiency and Clinical Outcomes with Chimeric Antigen Receptor T-Cell Therapy in Large B-cell Lymphoma

Vitamin D insufficiency is a potentially modifiable risk factor for poor outcomes in newly diagnosed large B-cell lymphoma (LBCL). However, the role of circulating vitamin D concentrations in relapsed/refractory LBCL treated with CD19-directed chimeric antigen receptor T-cell therapy (CAR-T) is currently unknown. This was a single-center, observational study that evaluated the association of pre-CAR-T 25-hydroxyvitamin D (25-OHD) status with 100-day complete response, progression-free survival, overall survival, and CAR-T-related toxicity in 111 adult relapsed/refractory LBCL patients. Vitamin D insufficiency was defined as ≤30 ng/mL in accordance with the Endocrine Society guidelines. The median pre-CAR-T 25-hydroxyvitamin D concentration was 24 ng/mL (interquarile range = 18-34). Vitamin D-insufficient patients (≤30 ng/mL; n = 73 [66%]) were significantly younger than their vitamin D-replete (>30 ng/mL; n = 38 [34%]) counterparts (P= .039). The vitamin D-insufficient cohort was enriched for de novo LBCL as the histological subtype (P= .026) and had a higher proportion of tisagenlecleucel as the CAR-T product (P= .049). There were no other significant differences in the baseline characteristics between the two groups. In vitamin D-insufficient compared to -replete patients, 100-day complete response was 55% versus 76% (P= .029), and 2-year overall survival was 41% versus 71% (P= .061), respectively. In multivariate analysis, vitamin D insufficiency remained significantly associated with 100-day complete response (odds ratio 2.58 [1.05-6.83]; P= .045) and overall survival (hazard ratio 2.24 [1.08-4.66], P= .030). In recipients of tisagenlecleucel, vitamin D insufficiency was associated with significantly lower cell viability of the infused CAR-T product (P= .015). Finally, pretreatment vitamin D insufficiency did not predict for subsequent CAR-T-related toxicity. This is the first report to demonstrate that vitamin D insufficiency is associated with inferior clinical outcomes in CAR-T recipients. Further study into the mechanistic insights of this finding, and the potential role of vitamin D supplementation to optimize CAR-T are warranted.

TP53 mutations and RNA-binding protein MUSASHI-2 drive resistance to PRMT5-targeted therapy in B-cell lymphoma

To identify drivers of sensitivity and resistance to Protein Arginine Methyltransferase 5 (PRMT5) inhibition, we perform a genome-wide CRISPR/Cas9 screen. We identify TP53 and RNA-binding protein MUSASHI2 (MSI2) as the top-ranked sensitizer and driver of resistance to specific PRMT5i, GSK-591, respectively. TP53 deletion and TP53^R248W mutation are biomarkers of resistance to GSK-591. PRMT5 expression correlates with MSI2 expression in lymphoma patients. MSI2 depletion and pharmacological inhibition using Ro 08-2750 (Ro) both synergize with GSK-591 to reduce cell growth. Ro reduces MSI2 binding to its global targets and dual treatment of Ro and PRMT5 inhibitors result in synergistic gene expression changes including cell cycle, P53 and MYC signatures. Dual MSI2 and PRMT5 inhibition further blocks c-MYC and BCL-2 translation. BCL-2 depletion or inhibition with venetoclax synergizes with a PRMT5 inhibitor by inducing reduced cell growth and apoptosis. Thus, we propose a therapeutic strategy in lymphoma that combines PRMT5 with MSI2 or BCL-2 inhibition.

Inhibition of the protein arginine methyltransferase PRMT5 has been suggested as a promising therapy for lymphoma. Here, the authors show that TP53 loss of function and MUSASHI-2 (MSI2) expression are biomarkers of resistance to PRMT5-targeted therapy in B-cell lymphoma. Moreover, combining PRMT5 inhibition with MSI2 or BCL-2 inhibitors blocks the translation of key drivers of lymphoma, c-MYC and BCL-2, inhibiting cell growth.

Taking the EZ way: Targeting enhancer of zeste homolog 2 in B-cell lymphomas

Enhancer of zeste homolog 2 (EZH2) is an epigenetic regulator that controls the normal biology of germinal B cells. Overexpression or mutation of EZH2 is associated with malignant transformation in a number of B-cell malignancies; thus, EZH2 inhibitors are an attractive therapeutic option for these targets. Several EZH2 inhibitors have entered clinical trials, but there remains an important question as to how EZH2 inhibitor mechanism of action differs in patients with mutant and wild-type EZH2. This review discusses the EZH2-driven mechanisms that lead to the development of B-cell lymphomas and act as therapeutic targets. Another key area of investigation is whether EZH2 inhibitors will work synergistically with existing immunomodulatory drugs and chemotherapy regimens. In summary, EZH2 inhibitors show potential as treatment for a range of B-cell lymphomas, and numerous clinical evaluations are currently underway.

Updated interim analysis of the randomized phase 1b/3 study of tazemetostat in combination with lenalidomide and rituximab in patients with relapsed/refractory follicular lymphoma

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Background: Tazemetostat (TAZ), an enhancer of zeste homolog 2 (EZH2) inhibitor, showed antitumor activity as monotherapy in patients with relapsed or refractory (R/R) follicular lymphoma (FL) who received ≥2 prior lines of therapy. In clinical studies in patients with R/R FL, lenalidomide and rituximab (R2) demonstrated an objective response rate (ORR) of 73%–78% and median progression-free survival (PFS) of 36–39 months. This global, multicenter phase 1b/3 study is designed to determine the recommended phase 3 dose (RP3D), efficacy, and safety of TAZ + R2 in patients with R/R FL after ≥1 prior therapy. We report an updated interim analysis of the phase 1b safety run-in where we assess the clinical activity and pharmacokinetics (PK) of TAZ when administered with R2 in patients with R/R FL. Methods: Phase 1b evaluated TAZ at 3 dose levels (400, 600, and 800 mg orally twice daily) in 28-day cycles with standard-dose R2 (NCT04224493). In addition to PK and safety, preliminary efficacy analysis was performed on the response-evaluable population, including best overall response, PFS, and duration of response (DOR) per investigator assessment according to Lugano 2014 response criteria. Results: As of January 22, 2022, 43 patients were enrolled and receiving TAZ + R2 (400 [n = 4], 600 [n = 18], and 800 mg [n = 21]). These patients had a median age of 67 years (range, 39–83) and received a median of 1 prior therapy (range, 1–4). Overall, 15/43 (34.9%) patients were refractory to rituximab, 10/39 (25.6%) had POD24, and 6/41 (14.6%) had mutant-type EZH2. Median duration of treatment exposure was 32.0 weeks (range, 4.1–68.1). Mean Cmax and AUC0–t of TAZ 800 mg + R2 at steady state were similar to those found for TAZ as monotherapy. PK of TAZ was not altered by concomitant administration of daily oral lenalidomide 20 mg, and PK of lenalidomide was not altered by concomitant administration of TAZ. No dose-limiting toxicities were observed in phase 1b, and no new safety signals were identified as of the January 2022 data cutoff. Serious treatment-emergent adverse events (TEAEs) were observed in 14 (32.6%) patients. Grade 3–4 TEAEs were observed in 24 (55.8%) patients; the most common grade 3–4 TEAE was neutrophil count decrease (n = 13; 30.2%). Of 38 patients evaluable for tumor assessment, 19 (50.0%) had a complete response, 17 (44.7%) had a partial response, and 2 (5.3%) had stable disease. ORR was 94.7% (n = 36). With a median follow-up of 5.8 months, median PFS and DOR were not reached and appeared to be similar, regardless of mutation status. Conclusions: TAZ + R2 combination demonstrates consistent and unaltered PK for TAZ and lenalidomide as well as a favorable safety profile and efficacy trend. The 2-arm randomized phase 3 portion will further explore the efficacy and safety of TAZ RP3D 800 mg + R2 in ≈500 patients with R/R FL. Clinical trial information: NCT04224493.

Impact of TP53 Genomic Alterations in Large B-Cell Lymphoma Treated With CD19-Chimeric Antigen Receptor T-Cell Therapy

PURPOSE

Tumor-intrinsic features may render large B-cell lymphoma (LBCL) insensitive to CD19-directed chimeric antigen receptor T cells (CAR-T). We hypothesized that TP53 genomic alterations are detrimental to response outcomes in LBCL treated with CD19-CAR-T.

MATERIALS AND METHODS

Patients with LBCL treated with CD19-CAR-T were included. Targeted next-generation sequencing was performed on pre-CAR-T tumor samples in a subset of patients. Response and survival rates by histologic, cytogenetic, and molecular features were assessed. Within a cohort of newly diagnosed LBCL with genomic and transcriptomic profiling, we studied interactions between cellular pathways and TP53 status.

RESULTS

We included 153 adults with relapsed or refractory LBCL treated with CD19-CAR-T (axicabtagene ciloleucel [50%], tisagenlecleucel [32%], and lisocabtagene maraleucel [18%]). Outcomes echoed pivotal trials: complete response (CR) rate 54%, median overall survival (OS) 21.1 months (95% CI, 14.8 to not reached), and progression-free survival 6 months (3.4 to 9.7). Histologic and cytogenetic LBCL features were not predictive of CR. In a subset of 82 patients with next-generation sequencing profiling, CR and OS rates were comparable with the unsequenced cohort. TP53 alterations (mutations and/or copy number alterations) were common (37%) and associated with inferior CR and OS rates in univariable and multivariable regression models; the 1-year OS in TP53-altered LBCL was 44% (95% CI, 29 to 67) versus 76% (65 to 89) in wild-type (P = .012). Transcriptomic profiling from a separate cohort of patients with newly diagnosed lymphoma (n = 562) demonstrated that TP53 alterations are associated with dysregulation of pathways related to CAR-T-cell cytotoxicity, including interferon and death receptor signaling pathway and reduced CD8 T-cell tumor infiltration.

CONCLUSION

TP53 is a potent tumor-intrinsic biomarker that can inform risk stratification and clinical trial design in patients with LBCL treated with CD19-CAR-T. The role of TP53 should be further validated in independent cohorts.

Phase I/Ib Study of the Efficacy and Safety of Buparlisib and Ibrutinib Therapy in MCL, FL, and DLBCL with Serial Cell-Free DNA Monitoring

PURPOSE

Activation of Bruton tyrosine kinase (BTK) and phosphatidylinositol-3-kinase (PI3K) represent parallel, synergistic pathways in lymphoma pathogenesis. As predominant PI3Kδ inhibition is a possible mechanism of tumor escape, we proposed a clinical trial of dual BTK and pan-PI3K inhibition.

PATIENTS AND METHODS

We conducted a single-center phase I/Ib trial combining a BTK inhibitor (ibrutinib) and a pan-PI3K inhibitor (buparlisib) in 37 patients with relapsed/refractory (R/R) B-cell lymphoma. Buparlisib and ibrutinib were administered orally, once daily in 28-day cycles until progression or unacceptable toxicity. The clinical trial is registered with clinicaltrials.gov, NCT02756247.

RESULTS

Patients with mantle cell lymphoma (MCL) receiving the combination had a 94% overall response rate (ORR) and 33-month median progression-free survival; ORR of 31% and 20% were observed in patients with diffuse large B-cell lymphoma and follicular lymphoma, respectively. The maximum tolerated dose was ibrutinib 560 mg plus buparlisib 100 mg and the recommended phase II dose was ibrutinib 560 mg plus buparlisib 80 mg. The most common grade 3 adverse events were rash/pruritis/dermatitis (19%), diarrhea (11%), hyperglycemia (11%), and hypertension (11%). All grade mood disturbances ranging from anxiety, depression, to agitation were observed in 22% of patients. Results from serial monitoring of cell-free DNA samples corresponded to radiographic resolution of disease and tracked the emergence of mutations known to promote BTK inhibitor resistance.

CONCLUSIONS

BTK and pan-PI3K inhibition in mantle cell lymphoma demonstrates a promising efficacy signal. Addition of BCL2 inhibitors to a BTK and pan-PI3K combination remain suitable for further development in mantle cell lymphoma.

Tazemetostat for patients with relapsed or refractory follicular lymphoma: an open-label, single-arm, multicentre, phase 2 trial

BACKGROUND

Activating mutations of EZH2, an epigenetic regulator, are present in approximately 20% of patients with follicular lymphoma. We investigated the activity and safety of tazemetostat, a first-in-class, oral EZH2 inhibitor, in patients with follicular lymphoma.

METHODS

This study was an open-label, single-arm, phase 2 trial done at 38 clinics or hospitals in France, the UK, Australia, Canada, Poland, Italy, Ukraine, Germany, and the USA. Eligible patients were adults (≥18 years) with histologically confirmed follicular lymphoma (grade 1, 2, 3a, or 3b) that had relapsed or was refractory to two or more systemic therapies, had an Eastern Cooperative Oncology Group performance status of 0-2, and had sufficient tumour tissue for central testing of EZH2 mutation status. Patients were categorised by EZH2 status: mutant (EZH2^mut) or wild-type (EZH2^WT). Patients received 800 mg of tazemetostat orally twice per day in continuous 28-day cycles. The primary endpoint was objective response rate based on the 2007 International Working Group criteria for non-Hodgkin lymphoma, assessed by an independent radiology committee. Activity and safety analyses were done in patients who received one dose or more of tazemetostat. This study is registered with ClinicalTrials.gov, NCT01897571, and follow-up is ongoing.

FINDINGS

Between July 9, 2015, and May 24, 2019, 99 patients (45 in the EZH2^mut cohort and 54 in the EZH2^WT cohort) were enrolled in the study. At data cutoff for the analysis (Aug 9, 2019), the median follow-up was 22·0 months (IQR 12·0-26·7) for the EZH2^mut cohort and 35·9 months (24·9-40·5) for the EZH2^WT cohort. The objective response rate was 69% (95% CI 53-82; 31 of 45 patients) in the EZH2^mut cohort and 35% (23-49; 19 of 54 patients) in the EZH2^{WT cohort.} Median duration of response was 10·9 months (95% CI 7·2-not estimable [NE]) in the EZH2^mut cohort and 13·0 months (5·6-NE) in the EZH2^WT cohort; median progression-free survival was 13·8 months (10·7-22·0) and 11·1 months (3·7-14·6). Among all 99 patients, treatment-related grade 3 or worse adverse events included thrombocytopenia (three [3%]), neutropenia (three [3%]), and anaemia (two [2%]). Serious treatment-related adverse events were reported in four (4%) of 99 patients. There were no treatment-related deaths.

INTERPRETATION

Tazemetostat monotherapy showed clinically meaningful, durable responses and was generally well tolerated in heavily pretreated patients with relapsed or refractory follicular lymphoma. Tazemetostat is a novel treatment for patients with follicular lymphoma.

FUNDING

Epizyme.

Tazemetostat for patients with relapsed or refractory follicular lymphoma: an open-label, single-arm, multicentre, phase 2 trial

BACKGROUND

Activating mutations of EZH2, an epigenetic regulator, are present in approximately 20% of patients with follicular lymphoma. We investigated the activity and safety of tazemetostat, a first-in-class, oral EZH2 inhibitor, in patients with follicular lymphoma.

METHODS

This study was an open-label, single-arm, phase 2 trial done at 38 clinics or hospitals in France, the UK, Australia, Canada, Poland, Italy, Ukraine, Germany, and the USA. Eligible patients were adults (≥18 years) with histologically confirmed follicular lymphoma (grade 1, 2, 3a, or 3b) that had relapsed or was refractory to two or more systemic therapies, had an Eastern Cooperative Oncology Group performance status of 0-2, and had sufficient tumour tissue for central testing of EZH2 mutation status. Patients were categorised by EZH2 status: mutant (EZH2^mut) or wild-type (EZH2^WT). Patients received 800 mg of tazemetostat orally twice per day in continuous 28-day cycles. The primary endpoint was objective response rate based on the 2007 International Working Group criteria for non-Hodgkin lymphoma, assessed by an independent radiology committee. Activity and safety analyses were done in patients who received one dose or more of tazemetostat. This study is registered with ClinicalTrials.gov, NCT01897571, and follow-up is ongoing.

FINDINGS

Between July 9, 2015, and May 24, 2019, 99 patients (45 in the EZH2^mut cohort and 54 in the EZH2^WT cohort) were enrolled in the study. At data cutoff for the analysis (Aug 9, 2019), the median follow-up was 22·0 months (IQR 12·0-26·7) for the EZH2^mut cohort and 35·9 months (24·9-40·5) for the EZH2^WT cohort. The objective response rate was 69% (95% CI 53-82; 31 of 45 patients) in the EZH2^mut cohort and 35% (23-49; 19 of 54 patients) in the EZH2^{WT cohort.} Median duration of response was 10·9 months (95% CI 7·2-not estimable [NE]) in the EZH2^mut cohort and 13·0 months (5·6-NE) in the EZH2^WT cohort; median progression-free survival was 13·8 months (10·7-22·0) and 11·1 months (3·7-14·6). Among all 99 patients, treatment-related grade 3 or worse adverse events included thrombocytopenia (three [3%]), neutropenia (three [3%]), and anaemia (two [2%]). Serious treatment-related adverse events were reported in four (4%) of 99 patients. There were no treatment-related deaths.

INTERPRETATION

Tazemetostat monotherapy showed clinically meaningful, durable responses and was generally well tolerated in heavily pretreated patients with relapsed or refractory follicular lymphoma. Tazemetostat is a novel treatment for patients with follicular lymphoma.

FUNDING

Epizyme.

Impact of interim PET on Hodgkin lymphoma treatment outcome and survival in clinical practice

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Background: FDG avidity above liver on interim PET (PET2) during frontline ABVD is considered a marker of impending treatment failure and an indication to switch to an intensified regimen. However, in clinical practice the utility of PET2 for treatment decisions is less clear. We describe outcomes of patients with positive PET2 who continued treatment with ABVD in the clinical setting. Methods: A retrospective study of all patients with newly diagnosed advanced-stage Hodgkin lymphoma treated with frontline ABVD at Memorial Sloan Kettering Cancer Center between 2008-2017. Eligibility criteria were set to correspond with the RATHL inclusion criteria (stage IIB - IV, or IIA bulky or ≥ 3 involved sites). We identified all PET2 reports indicating suspected residual uptake. All positive PET2 images were then reviewed by a single study radiologist. To increase reproducibility and avoid selection of borderline cases, we defined as PET2 positive only those cases with a lesion-to-liver (mean) SUV ratio ≥ 1.3. We also used a recently published stringent criterion of lesion-to-liver (max) ratio ≥ 1.4 (mPET2+). Progression-free and overall survival (PFS, OS) were calculated from the date of initial treatment until progression or death of any cause. Consolidative radiation was not considered a PFS event, and all progressions were verified by biopsy. Results: We identified 227 patients fitting RATHL inclusion criteria treated with ABVD. Median age was 34, with 25% (58) ≥ 45 years, 12% (26) had an IPS ≥ 4; 28% (64) stage II (5% II-X) and 38% (87) with extranodal involvement. 57 (25%) patients had a PET2 report indicating suspected residual lymphoma (PET2+), however, only 32 (14%) met the more stringent mPET2+ criterion. Most patients with PET2+ continued ABVD (84%, 48), and 9 switched to escBEACOPP (this subset of patients had substantially worse disease and are not the focus of this analysis). 21 (9%) patients received consolidative radiation. With a median follow-up of 47 months (42-54m), PET2+ patients who continued ABVD had a 3yPFS of 70% (58-85%, n = 48); mPET+ had a 3yPFS of 71% (55-92%, n = 24). Overall survival was excellent regardless of PET2 status (5yOS 97%). Conclusions: The outcome of PET2+ patients in this analysis was better than previously reported and the continuation of ABVD was appropriate for most patients. Use of a confirmatory biopsy is important for identifying true progressions. Patients with PET2+ had an excellent OS. Evaluation of the superiority of alternative regimens in PET2+ patients requires an ABVD comparator arm.

Phase Ib trial combining rapid determination of drug-drug interaction (DDI) followed by a dose finding period to assess safety and preliminary efficacy of fimepinostat plus venetoclax in patients with aggressive B-cell lymphoma

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Background: Fimepinostat (F), a dual inhibitor of PI3K (α, β, δ) and HDACs type 1/2, causes suppression of MYC levels (Shulman et al., 2017). A pooled analysis of diffuse large B-cell lymphoma (DLBCL) pts treated with F in two Ph 1/2 trials revealed an objective response rate in evaluable/ITT MYC-altered DLBCL pts of 29%/23%, respectively (Landsburg et al., 2018). Based on compelling preclinical activity of F in combination with venetoclax (V) (a Bcl2 inhibitor), we initiated a Ph 1b/2 study of F + V in pts with relapsed or refractory (R/R) DLBCL or high-grade B-cell lymphoma (HGBL), with or without MYC alteration. V is metabolized primarily by CYP3A, and preclinical studies showed that F may inhibit CYP3A4 (IC50 of 13.58 and 0.28 µM for midazolam and testosterone, respectively), suggesting F could cause DDI with V. Methods: Cohorts of patients received increasing dose levels of F administered on a 5-days-on/2-days-off (5/2) schedule in combination with daily V in 21-day cycles (Cohort 1: F 30 mg QD 5/2 + V 400 mg QD; Cohort 2: F 60 mg QD, 5/2 + V 400 mg QD; Cohort 3: F 60 mg QD 5/2 + V 800 mg QD). A potential DDI was assessed during Cycle 0 (Table), where PK for V (10 mg) monotherapy was compared to that for V (10 mg) in the presence of F. Patient PK samples were collected, analyzed and reviewed in < 10 days to determine the final ramp-up dose level of V. Results: As of 1-Feb-2020, 16 pts have been enrolled in 2 dose cohorts. Intensive PK analysis of 13 pts showed only mild (≤ 2-fold) to no increase in V exposure in the presence of F. In Cohort 1 (n = 6), the mean AUC increased 1.6-fold, and mean Cmax by 1.5-fold. In Cohort 2 (n = 7), no increase in mean AUC (0.9-fold) or Cmax (1.0-fold) was observed. Accordingly, all pts ramped up V to 100% of the target dose (400 mg) upon entering Cycle 1; rapid escalation of V was well tolerated. DLT was observed in 1 pt (Grade 3 diarrhea) in Cohort 2. Overall, 75% of TEAEs have been mild or moderate (Grade 1/2), and most were of limited duration. 11 pts (69%) experienced SAEs; 4 pts (25%) had SAEs considered related to either F or V. Conclusions: Real-time PK evaluation showed that F had only a mild to no DDI with V. F + V is well tolerated at clinically active dose levels, and evaluation of higher dose-level cohorts was ongoing. Enrollment in Cohort 2 remains on-going. Clinical trial information: NCT01742988 . [Table: see text]

Initial results of a multicenter, investigator initiated study of MRD driven time limited therapy with zanubrutinib, obinutuzumab, and venetoclax

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Background: Venetoclax (Ven)-Obinutuzumab (O) is approved for chronic lymphocytic leukemia (CLL) achieving frequent undetectable minimum residual disease (uMRD; Fischer NEJM 2019). Ven-Ibrutinib is synergistic with frequent uMRD but with grade >3 neutropenia in 33-48% patients (pts; Tam ASH 2019; Jain NEJM 2019). Zanubrutinib (B) is a highly specific BTK inhibitor that demonstrated 100% occupancy in lymphoid tissues, so may be preferred to combine with OVen. We hypothesize that treatment (tx) with BOVen using an MRD driven discontinuation strategy will achieve frequent uMRD and durable responses. Methods: In this multicenter, investigator initiated phase 2 trial (NCT03824483), eligible pts had previously untreated CLL requiring tx per iwCLL, ECOG PS <2, ANC >1, PLT >75 (ANC >0, PLT >20 if due to CLL). BOVen was administered in 28D cycles: B 160 mg PO BID starting D1; O 1000 mg IV D1 or split D1-2, 8, 15 of C1, D1 of C2-8; Ven ramp up initiated C3D1 (target 400 mg QD). Tx duration was determined by a prespecified uMRD endpoint (min 8 cycles). MRD was assessed in peripheral blood (PB; flow cytometry, sensitivity >10−4) starting C7D1 then every 2 cycles. Once PB uMRD was determined and confirmed in bone marrow (BM), tx continued 2 additional cycles. Adverse events (AE) were assessed per CTCAE v5. Median (med) time to uMRD (primary endpoint) was estimated using the Kaplan-Meier method. Results: The study accrued 39 pts (3-10/19): med age 59 years (23-73), 3:1 male, CLL IPI >4 26/39 (67%), unmutated IGHV 28/39 (72%), 17p del/ TP53 mutated 4/39 (10%), all pts were evaluable for toxicity with 37 evaluable for efficacy. At a med follow up of 8 months (mo; 3-10), 25/37 (68%) pts achieved PB uMRD. Med time to PB uMRD is 6 mo (4-8+). Another 8/37 (22%) had PB MRD < 0.1%. Of 25 with PB uMRD, 19 had BM uMRD with 10/19 completing 2 additional cycles and discontinued; 3 had BM MRD (all <0.02%); 3 pending. The most common tx emergent AEs were neutropenia (49%), infusion related reaction (41%), bruising (39%), and diarrhea (39%). Grade ≥3 AEs in ≥5% pts were neutropenia (13%), thrombocytopenia (5%), rash (5%), and pneumonia (5%). Of 17 pts at high risk for TLS on C1D1, 2 cycles of BO reduced TLS risk to low/medium at Ven initiation in 15 (88%). No pts had laboratory/clinical TLS (Howard). Conclusions: BOVen is well tolerated and achieves rapid uMRD: currently 68% PB uMRD and 51% BM uMRD with limited follow up (to be updated on presentation). Ten (27%) have discontinued treatment thus far. The value of MRD directed treatment duration will be evaluated with continued follow up. Clinical trial information: NCT03824483 .

Early data from a phase II trial investigating the combination of pembrolizumab (PEM) and entinostat (ENT) in relapsed and refractory (R/R) Hodgkin lymphoma (HL)

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Background: Histone deacetylase (HDAC) inhibitors have single agent activity in various types of lymphoma. They have been shown to restore antigen-specific immune recognition in cancer cells and to downregulate PD-1 expression in circulating T lymphocytes. In preclinical studies, the combination of HDAC inhibitors and anti-PD-1 antibodies acts synergistically against various tumor models in mice. Accordingly, we investigated the safety and efficacy of the novel combination of the HDAC inhibitor ENT and the PD-1-blocking antibody PEM in patients with R/R HL. Methods: Patients with R/R HL received ENT 5-7 mg orally once weekly and PEM 200 mg intravenously once every three weeks. The primary objective is overall response rate (ORR) and 12-month progression-free survival (PFS). Multiplexed serum cytokine analysis of 20 pro-inflammatory cytokines and chemokines was performed on sera from peripheral blood samples collected at baseline and at 21 days on treatment. Results: At data cutoff on 2/5/20, 14 patients with HL have been enrolled. Out of 13 evaluable patients, 12 responded (92% ORR), including 3 who progressed on prior anti-PD-1 therapy. With a median duration of follow-up of 176 days (21-632), 9 patients are currently receiving treatment on study, 2 discontinued due to toxicity, 1 for progression, and 2 for consolidation with transplant or radiation. After 21 days on treatment, there was a decrease in median serum levels of eotaxin (-39%, p = 0.002), eotaxin-3 (-56%, p = 0.04), MDC (-78%, p = 0.025), MIP1a (-60%, p = 0.025), and TARC (-98%, p < 0.001) and a 3-fold increase in median levels of IFNγ (p = 0.032). There was an association between extent of tumor reduction and greater decrease in the cytokines eotaxin-3 (-62%, p = 0.064), MDC (-90%, p = 0.064), and MIP1a (-85%, p = 0.064), which trended towards statistical significance. Out of 22 total patients enrolled in this study (including 8 patients with follicular lymphoma), 62% had grade ≥3 adverse events (AE), which were predominantly hematologic, including neutropenia (48%), thrombocytopenia (19%), and anemia (10%). Immune-related AEs included 3 cases of hypothyroidism, 2 cases of hepatitis and 1 case of pneumonitis. Four patients who experienced serious AEs due to pericarditis (n = 2), hemophagocytic lymphohistiocytosis, and bullous dermatitis were taken off study. Conclusions: Early results from this ongoing phase II clinical trial suggest that the combination of PEM and ENT is safe with encouraging responses in HL. Clinical trial information: NCT03179930 .

Divergent clonal evolution of a common precursor to mantle cell lymphoma and classic Hodgkin lymphoma

Clonal heterogeneity and evolution of mantle cell lymphoma (MCL) remain unclear despite the progress in our understanding of its biology. Here, we report a 71-yr-old male patient with an aggressive MCL and depict the clonal evolution from initial diagnosis of typical MCL to relapsed blastoid MCL. During the course of the disease, the patient was diagnosed with classic Hodgkin lymphoma (CHL) and received a CHL therapeutic regimen. Molecular analysis by next-generation sequencing of both MCL and CHL demonstrated clonally related CHL with characteristic immunophenotype and PDL1/2 gains. Moreover, our data illustrate the clonal heterogeneity and acquisition of additional genetic aberrations including a rare fusion of SEC22B-NOTCH2 in the process of clonal evolution. Evidence obtained from our comprehensive immunophenotypic and genetic studies indicates that MCL and CHL can originate from a common precursor by divergent clonal evolution, which may pose a therapeutic challenge.

Noncovalent inhibitors reveal BTK gatekeeper and auto-inhibitory residues that control its transforming activity

Inhibition of Bruton tyrosine kinase (BTK) is a breakthrough therapy for certain B cell lymphomas and B cell chronic lymphatic leukemia. Covalent BTK inhibitors (e.g., ibrutinib) bind to cysteine C481, and mutations of this residue confer clinical resistance. This has led to the development of noncovalent BTK inhibitors that do not require binding to cysteine C481. These new compounds are now entering clinical trials. In a systematic BTK mutagenesis screen, we identify residues that are critical for the activity of noncovalent inhibitors. These include a gatekeeper residue (T474) and mutations in the kinase domain. Strikingly, co-occurrence of gatekeeper and kinase domain lesions (L512M, E513G, F517L, L547P) in cis results in a 10- to 15-fold gain of BTK kinase activity and de novo transforming potential in vitro and in vivo. Computational BTK structure analyses reveal how these lesions disrupt an intramolecular mechanism that attenuates BTK activation. Our findings anticipate clinical resistance mechanisms to a new class of noncovalent BTK inhibitors and reveal intramolecular mechanisms that constrain BTK's transforming potential.

Phase I dose escalation of ibrutinib and buparlisib in relapsed/refractory diffuse large B-cell lymphoma (DLBCL), mantle cell lymphoma (MCL), and follicular lymphoma (FL)

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Background: In vitro studies of BTK and PI3K inhibitors demonstrate synergy in non-Hodgkin lymphoma (NHL). We embarked on a phase I/Ib investigator-initiated clinical trial evaluating the combination of ibrutinib (BTK inhibitor) and buparlisib (pan-PI3K inhibitor) in relapsed/refractory (R/R) NHL. The completed dose escalation is reported. Methods: Patients (pts) were eligible if they had R/R DLBCL, MCL, or FL with ECOG≤2 and adequate organ function. Ibrutinib and buparlisib were given daily by mouth on a 28-day cycle. Dose reductions were permitted after cycle 1. Tumor response was based on Lugano Classification however CR required both PET resolution and ≥ PR by CT. Results: As of Dec 16, 2016, 13 pts were enrolled and evaluated for toxicity (DLBCL 5, FL 2, MCL 6). Dose levels and DLT per table. Six pts discontinued treatment for disease progression (DLBCL 4, FL 2). Hematologic AE ≥ grade 3 are anemia (2), leukocytosis (2), and leukopenia (4). Relevant non-hematologic AEs of any grade ≥ 20% across all pts were fatigue (77%), diarrhea (62%), anorexia (54%), rash (46%), hyperbilirubinemia (46%), gastric reflux (46%), CMV reactivation (31%), mood change (31%), and hypertension (23%). Most common related grade 3/4 toxicity is rash (N = 3). No grade 5 toxicities noted. Serious adverse events (SAE) include: grade 2 pleural effusion and grade 2 nausea (N = 1), grade 1 fever with hospitalization (N = 1), grade 2 confusion and grade 4 hyponatremia (N = 1) were unrelated to therapy. Responses noted in 13 pts: MCL (N = 6: CR 4, PR 2), FL (N = 2: SD 2), DLBCL (N = 5: SD 1). One CR was a MCL pt with CR after 2 cycles on combination therapy and continues in remission on ibrutinib alone because of buparlisib toxicity. Conclusions: Combination of ibrutinib and buparlisib while generally well tolerated has predicted toxicities of both BTK and PI3K inhibitors. The recommended phase 2 dose is ibrutinib 560 mg and buparlisib 100 mg though dose reductions for tolerability may be needed for long term oral therapies. Promising efficacy is observed in MCL. Clinical trial information: NCT02756247. [Table: see text]

ENGAGE- 501: phase II study of entinostat (SNDX-275) in relapsed and refractory Hodgkin lymphoma

Classical Hodgkin lymphoma treatment is evolving rapidly with high response rates from antibody-drug conjugates targeting CD30 and immune checkpoint antibodies. However, most patients do not achieve a complete response, therefore development of novel therapies is warranted to improve patient outcomes. In this phase II study, patients with relapsed or refractory Hodgkin lymphoma were treated with entinostat, an isoform selective histone deacetylase inhibitor. Forty-nine patients were enrolled: 33 patients on Schedule A (10 or 15 mg oral entinostat once every other week); 16 patients on Schedule B (15 mg oral entinostat once weekly in 3 of 4 weeks). Patients received a median of 3 prior treatments (range 1-10), with 80% of the patients receiving a prior stem cell transplant and 8% of patients receiving prior brentuximab vedotin. In the intention-to-treat analysis, the overall response rate was 12% while the disease control rate (complete response, partial response, and stable disease beyond 6 months) was 24%. Seven patients did not complete the first cycle due to progression of disease. Tumor reduction was observed in 24 of 38 (58%) evaluable patients. Median progression-free survival and overall survival was 5.5 and 25.1 months, respectively. The most frequent grade 3 or 4 adverse events were thrombocytopenia (63%), anemia (47%), neutropenia (41%), leukopenia (10%), hypokalemia (8%), and hypophosphatemia (6%). Twenty-five (51%) patients required dose reductions or delays. Pericarditis/pericardial effusion occurred in one patient after 12 cycles of therapy. Future studies are warranted to identify predictive biomarkers for treatment response and to develop mechanism-based combination strategies. (clinicaltrials.gov identifier: 00866333).