RB but not R-HCVAD is a feasible induction regimen prior to auto-HCT in frontline MCL: results of SWOG Study S1106

Aggressive induction chemotherapy followed by autologous haematopoietic stem cell transplant (auto-HCT) is effective for younger patients with mantle cell lymphoma (MCL). However, the optimal induction regimen is widely debated. The Southwestern Oncology Group S1106 trial was designed to assess rituximab plus hyperCVAD/MTX/ARAC (hyperfractionated cyclophosphamide, vincristine, doxorubicin and dexamethasone, alternating with high dose cytarabine and methotrexate) (RH) versus rituximab plus bendamustine (RB) in a randomized phase II trial to select a pre-transplant induction regimen for future development. Patients had previously untreated stage III, IV, or bulky stage II MCL and received either 4 cycles of RH or 6 cycles of RB, followed by auto-HCT. Fifty-three of a planned 160 patients were accrued; an unacceptably high mobilization failure rate (29%) on the RH arm prompted premature study closure. The estimated 2-year progression-free survival (PFS) was 81% vs. 82% and overall survival (OS) was 87% vs. 88% for RB and RH, respectively. RH is not an ideal platform for future multi-centre transplant trials in MCL. RB achieved a 2-year PFS of 81% and a 78% MRD negative rate. Premature closure of the study limited the sample size and the precision of PFS estimates and MRD rates. However, RB can achieve a deep remission and could be a platform for future trials in MCL.

General Biomarker Recommendations for Lymphoma

Lymphoid malignancies are a heterogeneous group of tumors that have distinctive clinical and biological behaviors. The increasing prevalence of disease reflects both treatment advances and the fact that some of these tumors are indolent. The ability to determine treatment needs at diagnosis remains problematic for some of the tumors, such as in follicular lymphomas. Major clinical advances will likely depend on precision oncology that will enable identification of specific disease entities, prognostic determination at diagnosis, and identification of precise therapeutic targets and essential pathways. However, refinement in diagnostic evaluation is an evolving science. The ability to determine prognosis at diagnosis is variable, and for many of the lymphoid malignancies prognosis can only be made after initial treatment. Clinical trials that aim to evaluate specific features of these diseases are required in order to advance clinical practice that meaningfully addresses this important public health challenge. Herein, we describe the process and general recommendation from the National Cancer Institute (NCI) clinical trials planning meeting in November 2014 to address clinical trial design and biomarker proposals in the context of NCI-supported lymphoma clinical trials in the National Clinical Trials Network.

Once-weekly ofatumumab in untreated or relapsed Waldenström's macroglobulinaemia: an open-label, single-arm, phase 2 study

BACKGROUND

The development of more effective and safer treatments, especially non-chemotherapeutics, is needed for patients with Waldenström's macroglobulinaemia. The aim of the study was to assess the safety and clinical activity of intravenous ofatumumab monotherapy for untreated and relapsed Waldenström's macroglobulinaemia.

METHODS

We did a phase 2, open-label, single-arm study at six centres (hospitals and cancer clinics) in the USA. Patients aged at least 18 years who were diagnosed with untreated or relapsed Waldenström's macroglobulinaemia and required treatment, received up to three cycles of weekly ofatumumab for 5 weeks. For cycle 1, patients received one of two treatment regimens. Group A received ofatumumab 300 mg during week 1 followed by 1000 mg during weeks 2-4. Because of the acceptable safety of the 1000 mg dose in treatment group A and clinical activity of the 2000 mg dose established in chronic lymphocytic leukaemia, the study was amended on Dec 9, 2009, to change cycle 1 for group B who received ofatumumab 300 mg during week 1 and 2000 mg during weeks 2-5. We followed up patients during weeks 5-16 for treatment group A and during weeks 6-16 for treatment group B (no treatment was given during this follow-up). Patients in both groups with stable disease or a minor response after 16 weeks were eligible to then receive a redosing cycle of ofatumumab 300 mg during week 1 and 2000 mg during weeks 2-5. We followed up patients during weeks 6-16 after the redosing cycle (no treatment was given during this follow-up). Patients responding to cycle 1 or the redosing cycle who developed disease progression within 36 months could receive cycle 2 of ofatumumab 300 mg during week 1 and 2000 mg during weeks 2-5. The primary endpoint for this study was the proportion of patients who achieved an overall response (complete responses plus partial responses plus minor responses) after each treatment cycle in the intent-to-treat population every 4 weeks starting at week 8. This trial is registered at www.ClinicalTrials.gov, NCT00811733, and is now complete.

FINDINGS

Between March 17, 2009, and Feb 24, 2011, we enrolled and assigned 37 patients to treatment (15 in treatment group A and 22 in treatment group B). All 37 were included in the efficacy and safety analyses. 19 (51%, 95% CI 34·4-68·1) of 37 patients achieved an overall response after cycle 1 and 22 (59%, 42·1-75·2) of 37 achieved an overall response after the redosing cycle; 15 (41%) with partial responses, seven (19%) with minor responses. 13 patients received treatment cycle 2; ten (77%) of the 13 achieved a response. All 37 patients had at least one adverse event; 16 (43%) patients had events of grade 3 or more (30 grade 3, one grade 4). The most common grade 3 or 4 adverse events were infusion reactions (four [11%] of 37), chest pain (two [5%] of 37), haemolysis (two [5%] of 37), and neutropenia (two [5%] of 37). Two (9%) of 22 patients (both in treatment group B) had an IgM flare. 12 patients reported serious adverse events; haemolysis and pyrexia were the most common (each occurring in two [5%] of 37 patients).

INTERPRETATION

A high proportion of patients achieved an overall response with ofatumumab monotherapy and this treatment was well tolerated, with a low incidence of IgM flare. This therapy might be a non-chemotherapeutic treatment option for patients with Waldenström's macroglobulinaemia, especially those with high IgM concentrations.

FUNDING

GlaxoSmithKline and Genmab.

Beyond RCHOP: A Blueprint for Diffuse Large B Cell Lymphoma Research

Diffuse large B cell lymphoma (DLBCL) comprises multiple molecular and biological subtypes, resulting in a broad range of clinical outcomes. With standard chemoimmunotherapy, there remains an unacceptably high treatment failure rate in certain DLBCL subsets: activated B cell (ABC) DLBCL, double-hit lymphoma defined by the dual translocation of MYC and BCL2, dual protein-expressing lymphomas defined by the overexpression of MYC and BCL2, and older patients and those with central nervous system involvement. The main research challenges for DLBCL are to accurately identify molecular subsets and to determine if specific chemotherapy platforms and targeted agents offer differential benefit. The ultimate goal should be to maximize initial cure rates to improve long-term survival while minimizing toxicity. In particular, a frontline trial should focus on biologically defined risk groups not likely to be cured with cyclophosphamide, doxorubicin, vincristine, and prednisone plus rituximab (R-CHOP). An additional challenge is to develop effective and personalized strategies in the relapsed setting, for which there is no current standard other than autologous stem cell transplantation, which benefits a progressively smaller proportion of patients. Relapsed/refractory DLBCL is the ideal setting for testing novel agents and new biomarker tools and will require a national call for biopsies to optimize discovery in this setting. Accordingly, the development of tools with both prognostic and predictive utility and the individualized application of new therapies should be the main priorities. This report identifies clinical research priorities for critical areas of unmet need in this disease.

Phase 1 trial of rituximab, lenalidomide, and ibrutinib in previously untreated follicular lymphoma: Alliance A051103

Chemoimmunotherapy in follicular lymphoma is associated with significant toxicity. Targeted therapies are being investigated as potentially more efficacious and tolerable alternatives for this multiply-relapsing disease. Based on promising activity with rituximab and lenalidomide in previously untreated follicular lymphoma (overall response rate [ORR] 90%-96%) and ibrutinib in relapsed disease (ORR 30%-55%), the Alliance for Clinical Trials in Oncology conducted a phase 1 trial of rituximab, lenalidomide, and ibrutinib. Previously untreated patients with follicular lymphoma received rituximab 375 mg/m2 on days 1, 8, 15, and 22 of cycle 1 and day 1 of cycles 4, 6, 8, and 10; lenalidomide as per cohort dose on days 1 to 21 of 28 for 18 cycles; and ibrutinib as per cohort dose daily until progression. Dose escalation used a 3+3 design from a starting dose level (DL) of lenalidomide 15 mg and ibrutinib 420 mg (DL0) to DL2 (lenalidomide 20 mg, ibrutinib 560 mg). Twenty-two patients were enrolled; DL2 was determined to be the recommended phase II dose. Although no protocol-defined dose-limiting toxicities were reported, a high incidence of rash was observed (all grades 82%, grade 3 36%). Eleven patients (50%) required dose reduction, 7 because of rash. The ORR for the entire cohort was 95%, and the 12-month progression-free survival was 80% (95% confidence interval, 57%-92%). Five patients developed new malignancies; 3 had known risk factors before enrollment. Given the increased toxicity and required dose modifications, as well as the apparent lack of additional clinical benefit to the rituximab-lenalidomide doublet, further investigation of the regimen in this setting seems unwarranted. The study was registered with www.ClinicalTrials.gov as #NCT01829568.

Abstract IA08: Reprogramming human cancer cells in CDK4/6 inhibitor therapy

CDK4 and CDK6 drive cell cycle progression through early G1 and are frequently deregulated in human cancer. Selective inhibition of CDK4/6 with palbociclib (PD 0332991) has demonstrated exciting clinical efficacy in diverse human cancers. However, the mechanism that discriminates sensitivity from resistance to targeting CDK4/6 remains obscure.

Mantle cell lymphoma (MCL) is an incurable non-Hodgkin's lymphoma where deregulated CDK4 activity and cyclin D1 expression underlies unrestrained proliferation and disease progression. In a phase I clinical trial in recurrent MCL, we demonstrated that palbociclib alone produced a durable clinical response with a favorable toxicity profile. To investigate the mechanism for targeting CDK4/6, we have now shown in primary cancer cells that 1) inhibition of CDK4/6 leads to early G1 arrest that requires Rb, the CDK4/6 substrate; 2) prolonged early G1 arrest (pG1) sensitizes Rb-proficient cancer cells to killing by diverse clinically-relevant agents; and 3) pG1 sensitization stems from continuous expression of genes scheduled for early G1 only. This leads to an imbalance in genes expression, which is exacerbated in synchronous progression to S phase (pG1-S) after palbociclib withdrawal, due to incomplete restoration of cell cycle-coupled gene expression.

In a hypothesis-driven phase Ib clinical trial, targeting CDK4 with palbociclib in sequential combination with the proteasome inhibitor bortezoimb was well tolerated (n=16). It exhibited a durable palbociclib dose-dependent clinical activity, including one complete remission for over 3 years with only one progression at the optimal dose combination (n=6). Longitudinal integrative whole transcriptome and whole exome sequencing of tumor cells isolated from serial lymph node biopsies demonstrated that palbociclib initially induced pG1 in MCL cells of all patients, regardless of copy number variation or mutation (ATM, p53). Cell cycle control by palbociclib is thus initially intact in MCL, but is insufficient to predict the clinical response.

As predicted, only genes programmed for early G1 were expressed pG1, concurrent PI3K inactivation in primary MCL cells. However, <1% of the 1400 genes suppressed (not programmed) in pG1 in clinically-responding patients were activated in non-responding patients. These genes were critical for redox homeostasis, suggesting that PI3K inactivation and redox stress mediates pG1 sensitization.

This study represents the first investigation of genes that discriminate sensitivity from resistance in targeting CDK4/CDK6 in human cancer, through integrative longitudinal analysis of whole exome and whole transcriptome sequencing in concert with protein expression analysis and functional studies. Selective inhibition of CDK4 induces pG1 in all MCL patients, which apparently reprograms MCL for clinical response to bortezomib through PI3K inactivation and suppression of genes for redox homeostasis.

Citation Format: Selina Chen-Kiang, Maurizio Di Liberto, Priyanka Vijay, David Chiron, Xiangao Huang, Scott Ely, Olivier Elemento, Christopher Mason, Lewis Cantley, John P. Leonard, Peter Martin. Reprogramming human cancer cells in CDK4/6 inhibitor therapy. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Cancer Cell Cycle - Tumor Progression and Therapeutic Response; Feb 28-Mar 2, 2016; Orlando, FL. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(11_Suppl):Abstract nr IA08.

Behavioral and physiological characterization of PKC-dependent phosphorylation in the Grin2a∆PKC mouse

Activity-dependent plasticity in NMDA receptor-containing synapses can be regulated by phosphorylation of serines and tyrosines in the C-terminal domain of the receptor subunits by various kinases. We have previously identified S1291/S1312 as important sites for PKC phosphorylation; while Y1292/Y1312 are the sites indirectly phosphorylated by PKC via Src kinase. In the oocyte expression system, mutation of those Serine sites to Alanine (that cannot be phosphorylated) in the GluN2A subunit, resulted in a decreased PKC stimulated current enhancement through the receptors compared to wild-type NMDA receptors. To investigate the behavioral and physiological significance of those PKC-mediated phosphorylation sites in vivo, the Grin2a∆PKC mouse expressing GluN2A with four mutated amino acids: S1291A, S1312A, Y1292F and Y1387F was generated using homologous recombination. The Grin2a∆PKC mice exhibit reduced anxiety in the open field test, light dark emergence test, and elevated plus maze. The mutant mice show reduced alternation in a Y maze spontaneous alternation task and a in a non-reinforced T maze alternation task. Interestingly, when the mutant mice were exposed to novel environments, there was no increase in context-induced Fos levels in hippocampal CA1 and CA3 compared to home-cage Fos levels, while the Fos increased in the WT mice in CA1, CA3 and DG. When the SC-CA1 synapses in slices from mutant mice were stimulated using a theta-burst protocol, there was no impairment in LTP. Overall, these results suggest that at least one of those PKC-mediated phosphorylation sites regulates NMDAR-mediated signaling that modulates anxiety.

Rationally designed BCL6 inhibitors target activated B cell diffuse large B cell lymphoma

Diffuse large B cell lymphomas (DLBCLs) arise from proliferating B cells transiting different stages of the germinal center reaction. In activated B cell DLBCLs (ABC-DLBCLs), a class of DLBCLs that respond poorly to current therapies, chromosomal translocations and amplification lead to constitutive expression of the B cell lymphoma 6 (BCL6) oncogene. The role of BCL6 in maintaining these lymphomas has not been investigated. Here, we designed small-molecule inhibitors that display higher affinity for BCL6 than its endogenous corepressor ligands to evaluate their therapeutic efficacy for targeting ABC-DLBCL. We used an in silico drug design functional-group mapping approach called SILCS to create a specific BCL6 inhibitor called FX1 that has 10-fold greater potency than endogenous corepressors and binds an essential region of the BCL6 lateral groove. FX1 disrupted formation of the BCL6 repression complex, reactivated BCL6 target genes, and mimicked the phenotype of mice engineered to express BCL6 with corepressor binding site mutations. Low doses of FX1 induced regression of established tumors in mice bearing DLBCL xenografts. Furthermore, FX1 suppressed ABC-DLBCL cells in vitro and in vivo, as well as primary human ABC-DLBCL specimens ex vivo. These findings indicate that ABC-DLBCL is a BCL6-dependent disease that can be targeted by rationally designed inhibitors that exceed the binding affinity of natural BCL6 ligands.

Therapeutic implication of concomitant chromosomal aberrations in patients with aggressive B-cell lymphomas

A subset of diffuse large B-cell lymphomas (DLBCL) harbors concomitant rearrangements of MYC, BCL2 and BCL6 and is characterized by clinical aggressiveness and intrinsic refractoriness to standard chemo-immunotherapy. Commonly identified as "double or triple hit" lymphomas, these diseases represent a therapeutic challenge to chemotherapy-based regimens and likely require a more targeted approach. Herein we summarize the unique biological behavior of double and triple hit lymphomas focusing on the coordinated network of pathways that enable cancer cells to tolerate the oncogenic stress imposed by the co-expression of MYC, BCL2 and BCL6. We discuss how these enabling pathways contribute to the chemo-refractoriness of these tumors. We propose to exploit lymphoma cells' addiction to these oncogenic networks to design combinatorial treatments for this aggressive disease based on the modulation of epigenetically-silenced pathways and decreasing expression and activity of these oncogenic drivers.

Targeting CD30 in hodgkin lymphoma: antibody-drug conjugates make a difference

CD30 expression is characteristic of the malignant Reed-Sternberg cell in Hodgkin lymphoma (HL) and several other lymphoid malignancies, such as anaplastic large-cell lymphoma (ALCL). Although unconjugated anti-CD30 antibodies have had minimal therapeutic activity in patients with HL as single agents, the CD30-directed antibody-drug conjugate (ADC) brentuximab vedotin has demonstrated activity that has resulted in its recent regulatory approval for the treatment of patients with relapsed HL and ALCL. Approximately 75% of patients with recurrent HL achieve objective responses, with the principal toxicity being peripheral neuropathy. Ongoing studies are evaluating treatment with this agent as part of first-line therapy, for patients with relapsed disease, and for patients with resistant disease and limited other options. Brentuximab vedotin demonstrates the therapeutic value of antibody-drug conjugation and serves as a model of how a novel, targeted approach can be employed to potentially further improve outcomes in settings where curative chemotherapeutic regimens are already available.

Outcomes of MYC-associated lymphomas after R-CHOP with and without consolidative autologous stem cell transplant: subset analysis of randomized trial intergroup SWOG S9704

Double hit lymphoma (DHL) and double protein-expressing (MYC, BCL2) lymphomas (DPL) fare poorly with R-CHOP (rituximab + cyclophosphamide, doxorubicin, vincristine, prednisolone); consolidative autologous stem cell transplant (ASCT) may improve outcomes. S9704, a phase III randomized study of CHOP +/-R with or without ASCT enabled evaluation of intensive consolidation. Immunohistochemistry (IHC) identified 27 of 198 patients (13·6%) with MYC overexpression; 20 (74%) harboured concurrent BCL2 overexpression. Four had DHL and 16 had DPL only. With median 127 months follow-up, there is a trend favouring outcomes after ASCT in DPL and MYC protein overexpressing patients, whereas all DHL patients have died irrespective of ASCT.

US Intergroup Trial of Response-Adapted Therapy for Stage III to IV Hodgkin Lymphoma Using Early Interim Fluorodeoxyglucose-Positron Emission Tomography Imaging: Southwest Oncology Group S0816

PURPOSE

Four US National Clinical Trials Network components (Southwest Oncology Group, Cancer and Leukemia Group B/Alliance, Eastern Cooperative Oncology Group, and the AIDS Malignancy Consortium) conducted a phase II Intergroup clinical trial that used early interim fluorodeoxyglucose positron emission tomography (FDG-PET) imaging to determine the utility of response-adapted therapy for stage III to IV classic Hodgkin lymphoma.

PATIENTS AND METHODS

The Southwest Oncology Group S0816 (Fludeoxyglucose F 18-PET/CT Imaging and Combination Chemotherapy With or Without Additional Chemotherapy and G-CSF in Treating Patients With Stage III or Stage IV Hodgkin Lymphoma) trial enrolled 358 HIV-negative patients between July 1, 2009, and December 2, 2012. A PET scan was performed after two initial cycles of doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) and was labeled PET2. PET2-negative patients (Deauville score 1 to 3) received an additional four cycles of ABVD, whereas PET2-positive patients (Deauville score 4 to 5) were switched to escalated bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisone (eBEACOPP) for six cycles. Among 336 eligible and evaluable patients, the median age was 32 years (range, 18 to 60 years), with 52% stage III, 48% stage IV, 49% International Prognostic Score 0 to 2, and 51% score 3 to 7.

RESULTS

Three hundred thirty-six of the enrolled patients were evaluable. Central review of the interim PET2 scan was performed in 331 evaluable patients, with 271 (82%) PET2-negative and 60 (18%) PET2-positive. Of 60 eligible PET2-positive patients, 49 switched to eBEACOPP as planned and 11 declined. With a median follow-up of 39.7 months, the Kaplan-Meier estimate for 2-year overall survival was 98% (95% CI, 95% to 99%), and the 2-year estimate for progression-free survival (PFS) was 79% (95% CI, 74% to 83%). The 2-year estimate for PFS in the subset of patients who were PET2-positive after two cycles of ABVD was 64% (95% CI, 50% to 75%). Both nonhematologic and hematologic toxicities were greater in the eBEACOPP arm than in the continued ABVD arm.

CONCLUSION

Response-adapted therapy based on interim PET imaging after two cycles of ABVD seems promising with a 2-year PFS of 64% for PET2-positive patients, which is much higher than the expected 2-year PFS of 15% to 30%.

Role of Surveillance Imaging in Patients With Peripheral T-Cell Lymphoma

INTRODUCTION

The role of surveillance imaging (SI) in patients with peripheral T-cell lymphoma (PTCL) in first complete remission (CR1) is unclear.

MATERIALS AND METHODS

Patients with PTCL were identified through prospectively maintained T-cell lymphoma databases from the National Cancer Centre Singapore/Singapore General Hospital and Weill-Cornell Medical College after institutional review board approval. Patients with leukemia or indolent, composite, and cutaneous lymphomas were excluded. The patients' medical records were retrospectively reviewed to determine the frequency and type of SI used. Of those with relapse, the method of relapse detection and data on symptoms, signs, and elevated lactate dehydrogenase LDH were extracted.

RESULTS

A total of 338 patients were included in the present study. In the first year after achieving CR1, patients had an average of 1.2 and a median of 1 SI performed (range, 0-4). In the second year after achieving CR1, they had an average of 0.78 and a median of 1 SI performed (range, 0-4). Of the 135 patients who achieved CR1, 61 (45%) developed a relapse. Relapses were detected before SI in 48 (84%), and 9 patients had relapses detected during routine SI. Of the 9 patients whose relapses were detected during planned SI, only 3 did not have any symptoms or signs suggestive of relapsed disease. Of these 3 patients, 2 had angioimmunoblastic T-cell lymphoma and 1 had natural killer/T-cell lymphoma.

CONCLUSION

Most PTCL relapses were detected before planned SI, and most patients had symptoms with relapse. Only 3 patients (5.2%) were completely asymptomatic at relapse, suggesting a limited utility of routine imaging for detecting PTCL relapses.

Foraging decisions in wild versus domestic Mus musculus: What does life in the lab select for?

What does domestication select for in terms of foraging and anti-predator behaviors? We applied principles of patch use and foraging theory to test foraging strategies and fear responses of three strains of Mus musculus: wild-caught, control laboratory, and genetically modified strains. Foraging choices were quantified using giving-up densities (GUDs) under three foraging scenarios: (1) patches varying in microhabitat (covered versus open), and initial resource density (low versus high); (2) daily variation in auditory cues (aerial predators and control calls); (3) patches with varying seed aggregations. Overall, both domestic strains harvested significantly more food than wild mice. Each strain revealed a significant preference for foraging under cover compared to the open, and predator calls had no detectable effects on foraging. Both domestic strains biased their harvest toward high quality patches; wild mice did not. In terms of exploiting favorable and avoiding unfavorable distributions of seeds within patches, the lab strain performed best, the wild strain worst, and the mutant strain in between. Our study provides support for hypothesis that domestic animals have more energy-efficient foraging strategies than their wild counterparts, but retain residual fear responses. Furthermore, patch-use studies can reveal the aptitudes and priorities of both domestic and wild animals.

Lenalidomide plus Rituximab as Initial Treatment for Mantle-Cell Lymphoma

BACKGROUND

Mantle-cell lymphoma is generally incurable. Initial treatment is not standardized but usually includes cytotoxic chemotherapy. Lenalidomide, an immunomodulatory compound, and rituximab, an anti-CD20 antibody, are active in patients with recurrent mantle-cell lymphoma. We evaluated lenalidomide plus rituximab as a first-line therapy.

METHODS

We conducted a single-group, multicenter, phase 2 study with induction and maintenance phases. During the induction phase, lenalidomide was administered at a dose of 20 mg daily on days 1 through 21 of every 28-day cycle for 12 cycles; the dose was escalated to 25 mg daily after the first cycle if no dose-limiting adverse events occurred during the first cycle and was reduced to 15 mg daily during the maintenance phase. Rituximab was administered once weekly for the first 4 weeks and then once every other cycle until disease progression. The primary end point was the overall response rate. Secondary end points included outcomes related to safety, survival, and quality of life.

RESULTS

A total of 38 participants were enrolled at four centers from July 2011 through April 2014. The median age was 65 years. On the basis of the Mantle Cell Lymphoma International Prognostic Index scores, the proportions of participants with low-risk, intermediate-risk, and high-risk disease at baseline were similar (34%, 34%, and 32%, respectively). The most common grade 3 or 4 adverse events were neutropenia (in 50% of the patients), rash (in 29%), thrombocytopenia (in 13%), an inflammatory syndrome ("tumor flare") (in 11%), anemia (in 11%), serum sickness (in 8%), and fatigue (in 8%). At the median follow-up of 30 months (through February 2015), the overall response rate among the participants who could be evaluated was 92% (95% confidence interval [CI], 78 to 98), and the complete response rate was 64% (95% CI, 46 to 79); median progression-free survival had not been reached. The 2-year progression-free survival was estimated to be 85% (95% CI, 67 to 94), and the 2-year overall survival 97% (95% CI, 79 to 99). A response to treatment was associated with improvement in quality of life.

CONCLUSIONS

Combination biologic therapy consisting of lenalidomide plus rituximab was active as initial therapy for mantle-cell lymphoma. (Funded by Celgene and Weill Cornell Medical College; ClinicalTrials.gov number, NCT01472562.).

Pharmacoproteomics identifies combinatorial therapy targets for diffuse large B cell lymphoma

Rationally designed combinations of targeted therapies for refractory cancers, such as activated B cell-like diffuse large B cell lymphoma (ABC DLBCL), are likely required to achieve potent, durable responses. Here, we used a pharmacoproteomics approach to map the interactome of a tumor-enriched isoform of HSP90 (teHSP90). Specifically, we chemically precipitated teHSP90-client complexes from DLBCL cell lines with the small molecule PU-H71 and found that components of the proximal B cell receptor (BCR) signalosome were enriched within teHSP90 complexes. Functional assays revealed that teHSP90 facilitates BCR signaling dynamics by enabling phosphorylation of key BCR signalosome components, including the kinases SYK and BTK. Consequently, treatment of BCR-dependent ABC DLBCL cells with PU-H71 attenuated BCR signaling, calcium flux, and NF-κB signaling, ultimately leading to growth arrest. Combined exposure of ABC DLBCL cell lines to PU-H71 and ibrutinib, a BCR pathway inhibitor, more potently suppressed BCR signaling than either drug alone. Correspondingly, PU-H71 combined with ibrutinib induced synergistic killing of lymphoma cell lines, primary human lymphoma specimens ex vivo, and lymphoma xenografts in vivo, without notable toxicity. Together, our results demonstrate that a pharmacoproteome-driven rational combination therapy has potential to provide more potent BCR-directed therapy for ABC DLCBL patients.

Randomized Trial of Lenalidomide Alone Versus Lenalidomide Plus Rituximab in Patients With Recurrent Follicular Lymphoma: CALGB 50401 (Alliance)

PURPOSE

Lenalidomide and rituximab (LR) are active agents in follicular lymphoma (FL). Combination regimens have not been previously assessed in randomized studies.

PATIENTS AND METHODS

The Cancer and Leukemia Group B (Alliance) 50401 trial is a randomized phase II trial studying rituximab (375 mg/m(2) weekly for 4 weeks), lenalidomide (15 mg per day on days 1 to 21, followed by 7 days of rest, in cycle 1 and then 20 mg per day on days 1 to 21, followed by 7 days of rest, in cycles 2 to 12), or LR. The rituximab-alone arm was discontinued as a result of poor accrual. Eligibility included recurrent FL and prior rituximab with time to progression of ≥ 6 months from last dose. Aspirin or heparin was recommended for patients at high thrombosis risk.

RESULTS

Ninety-one patients (lenalidomide, n = 45; LR, n = 46) received treatment; median age was 63 years (range, 34 to 89 years), and 58% were intermediate or high risk according to the Follicular Lymphoma International Prognostic Index. In the lenalidomide and LR arms, grade 3 to 4 adverse events occurred in 58% and 53% of patients, with 9% and 11% of patients experiencing grade 4 toxicity, respectively; grade 3 to 4 adverse events included neutropenia (16% v 20%, respectively), fatigue (9% v 13%, respectively), and thrombosis (16% [n = 7] v 4% [n = 2], respectively; P = .157). Thirty-six percent of lenalidomide patients and 63% of LR patients completed 12 cycles. Lenalidomide alone was associated with more treatment failures, with 22% of patients discontinuing treatment as a result of adverse events. Dose-intensity exceeded 80% in both arms. Overall response rate was 53% (20% complete response) and 76% (39% complete response) for lenalidomide alone and LR, respectively (P = .029). At the median follow-up of 2.5 years, median time to progression was 1.1 year for lenalidomide alone and 2 years for LR (P = .0023).

CONCLUSION

LR is more active than lenalidomide alone in recurrent FL with similar toxicity, warranting further study in B-cell non-Hodgkin lymphoma as a platform for addition of novel agents.

Abstract 3095: Longitudinal integrative whole transcriptome and exome sequencing identifies genes that reprogram lymphoma cells for clinical response to CDK4/6 inhibition in combination therapy

CDK4 and CDK6 drive cell cycle progression through early G1 and are frequently deregulated in human cancer. The selective inhibitor palbociclib (PD 0332991) demonstrated exciting clinical efficacy in diverse human cancers, notably in metastatic breast cancer where it more than doubled the progression free survival of patients treated with letrozole. In mantle cell lymphoma (MCL), deregulated CDK4 and cyclin D1 expression underlies unrestrained proliferation and disease progression. In a phase I clinical trial in recurrent MCL, we showed that palbociclib produced a durable clinical response. However, the mechanism that discriminates sensitivity from resistance to targeting CDK4/6 remains obscure.

To address this question, we demonstrated that 1) inhibition of CDK4/6 leads to early G1 arrest that requires Rb, the CDK4/6 substrate; 2) prolonged early G1 arrest (pG1) sensitizes Rb+ cancer cells to killing by diverse clinically-relevant agents; and 3) pG1 sensitization stems from continuous expression of genes scheduled for early G1 only. This sensitization is exacerbated in synchronous progression to S phase (pG1-S) after palbociclib withdrawal, due to incomplete restoration of cell cycle-coupled gene expression. In a hypothesis-driven phase Ib clinical trial we further showed that palbociclib induces pG1 and sensitizes MCL cells to the proteasome inhibitor bortezomib. At the optimal dose of palbociclib, only one in 6 patients progressed, and 4 patients had a durable responses including a complete remission for >800 days.

Longitudinal integrative whole transcriptome and whole exome sequencing of tumor cells from serial lymph node biopsies demonstrated that cell cycle control by palbociclib is initially intact in Rb+ MCL but is insufficient to predict clinical response. Palbociclib induced pG1 in all patients initially regardless of the subsequent clinical response or patient-specific copy number variation or mutation (ATM, p53). As expected, pG1 maintained the expression of cell cycle genes programmed for early G1 and suppressed those scheduled for other phases, and this was reversible upon release of the early G1 block.

However, expressing only genes scheduled for early G1 led to an imbalance in gene expression. Of the 1483 genes suppressed in pG1 compared with the baseline in Responders (Rs) (N = 4), 5 were up-regulated in Non-Responders (NRs) (N = 3); 11 of the 2041 genes up-regulated in pG1 in R were suppressed in NR. These oppositely expressed genes are involved in redox stress and metabolism based on functional analysis, suggesting a role for cell cycle-coupled metabolic imbalance in differential clinical response to targeting CDK4/6. Further validation of these candidate genes in the context of clinical response should advance the mechanism for therapeutic targeting of CDK4/6 as well as genome-based therapy and patient stratification.

Citation Format: Maurizio Di Liberto, Peter Martin, David Chiron, Priyanka Vijay, Xiangao Huang, Pedro Blecua, Scott Ely, Olivier Elemento, John P. Leonard, Christopher E. Mason, Selina Chen-Kiang. Longitudinal integrative whole transcriptome and exome sequencing identifies genes that reprogram lymphoma cells for clinical response to CDK4/6 inhibition in combination therapy. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3095. doi:10.1158/1538-7445.AM2015-3095

Abstract 3099: Longitudinal genomic and transcriptomic analysis of mantle cell lymphoma in a targeted combination trial of a selective CDK4/6 inhibitor

We used whole exome (WES) and whole transcriptome sequencing (WTS) to study progression of Mantle Cell Lymphoma (MCL) in the context of a clinical trial of targeted combination therapy of a CDK4 inhibitor PD0332991 (palbociclib) and a proteasome inhibitor bortezomib. Our longitudinal study design coupled with an integrative analysis approach enabled detailed molecular characterization of each subject's disease. This includes multiple time points for three therapy Responders (Rs) and two Non-Responders (NRs); a primary goal was to understand genetic reasons for differential response. To that end, we identified copy number variants (CNVs) and single nucleotide variants (SNVs) specific to NRs that are supported by both WES and WTS data and implicate pathways relevant to mechanisms of drug action.

CNVs were identified using multiple orthogonal methods that use read depth and genome-wide allele frequencies. These revealed a 29Mb chr9 hemizygous deletion unique to NRs. This region includes 15 interferon genes of the type 1 interferon signaling pathway (enrichment: p<10-9), which is involved in B cell differentiation and proliferation, and T cell and natural killer cell activation. Interferon signaling is implicated in bortezomib function and loss of interferon genes may contribute to resistance in non-responders. Additional key genes in deleted regions are JAK2, RPS6, and CDKN2A, a CDK2 inhibitor, loss of which may antagonize palbociclib-induced G1 arrest NRs also shared a 24Mb chr3 duplication resulting in gain of PIK3CA and PIK3CB. Amplification of these genes is common in cancers, including MCL (classical analysis) and DLBCL, and often associated with poor prognosis. But, this is the only longitudinal study of PI3K CNV in a targeted therapy. In context of PD+bortezomib treatment, higher levels of PI3K may affect sensitivity to proteasome inhibition activated autophagy since bortezomib's inhibitory activity involves suppression of the PI3K/AKT/mTOR pathway. PIK3CA is amplified in a responder as well, suggesting additional determinants for clinical response.

Other CNVs differentiating Rs and NRs are a 24Mb chr8 deletion found only in Rs and a 4Mb chr17 deletion found only in NRs, which includes p53 in a subject who also has a p53 mutation, resulting in 100% expression of the mutant allele. The described CNVs result in detectable shifts in expression of a large proportion of affected genes. Coupled with SNV data, where we identified 21 SNVs shared by NRs and absent in Rs, these results offer molecular clues to mechanisms of resistance in NRs, which we are currently pursuing with functional studies.

Overall, we performed a thorough genomic and transcriptomic analysis of a longitudinal investigation of MCL patients during a targeted combination therapy phase I clinical trial and identified potential biomarkers of response spanning CNVs, SNVs, and differentially expressed genes.

Citation Format: Priyanka Vijay, Pedro Blecua, Maurizio Di Liberto, David Chiron, Xiangao Huang, Olivier Elemento, Peter Martin, John P. Leonard, Christopher E. Mason, Selina Chen-Kiang. Longitudinal genomic and transcriptomic analysis of mantle cell lymphoma in a targeted combination trial of a selective CDK4/6 inhibitor. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3099. doi:10.1158/1538-7445.AM2015-3099

Clinical and molecular epidemiology of human rhinovirus infections in patients with hematologic malignancy

BACKGROUND

Human rhinoviruses (HRVs) are common causes of upper respiratory tract infection (URTI) in hematologic malignancy (HM) patients. Predictors of lower respiratory tract infection (LRTI) including the impact of HRV species and types are poorly understood.

OBJECTIVES

This study aims to describe the clinical and molecular epidemiology of HRV infections among HM patients.

STUDY DESIGN

From April 2012-March 2013, HRV-positive respiratory specimens from symptomatic HM patients were molecularly characterized by analysis of partial viral protein 1 (VP1) or VP4 gene sequence. HRV LRTI risk-factors and outcomes were analyzed using multivariable logistic regression.

RESULTS

One hundred and ten HM patients presented with HRV URTI (n=78) and HRV LRTI (n=32). Hypoalbuminemia (OR 3.0; 95% CI, 1.0-9.2; p=0.05) was independently associated with LRTI, but other clinical and laboratory markers of host immunity did not differ between patients with URTI versus LRTI. Detection of bacterial co-pathogens was common in LRTI cases (25%). Among 92 typeable respiratory specimens, there were 58 (64%) HRV-As, 12 (13%) HRV-Bs, and 21 (23%) HRV-Cs, and one Enterovirus 68. LRTI rates among HRV-A (29%), HRV-B (17%), and HRV-C (29%) were similar. HRV-A infections occurred year-round while HRV-B and HRV-C infections clustered in the late fall and winter.

CONCLUSIONS

HRVs are associated with LRTI in HM patients. Illness severity is not attributable to specific HRV species or types. The frequent detection of bacterial co-pathogens in HRV LRTIs further substantiates the hypothesis that HRVs predispose to bacterial superinfection of the lower airways, similar to that of other community-acquired respiratory viruses.

Abstract IA28: PI3K and mTOR inhibitors in lymphoid malignancies: Clinical data

Activation of pathways associated with PI3 Kinase and mTOR is commonly associated with a variety of lymphoid cancers, and can result in cell survival, growth and resistance to standard chemoimmunotherapeutics. Strong preclinical rationale has led to several agents that have been evaluated in clinical trials, both as monotherapy and in combination strategies. The mTOR inhibitors everolimus Iand temsirolimus have demonstrated clear clinical activity and acceptable toxicity profiles in patients with a variety of lymphoid malignancies. Temsirolimus has been approved in the European Union and several other countries outside of the US for the treatment of relapsed and/or refractory mantle cell lymphoma. This approval was based on a phase 3 randomized trial comparing temsirolimus at 2 dosing levels vs. investigator's therapy choice, which demonstrated an improvement in progression-free survival and overall response rate. Single agent activity of temsirolimus has also been demonstrated in other lymphoma subtypes such as diffuse large B cell and follicular lymphoma, and combination studies have been performed with rituximab. Everolimus has also been evaluated in mantle cell, diffuse large B cell and follicular lymphoma, as well as Hodgkin lymphoma, and clinical activity has also been noted. Combination studies with histone deacetylase inhibitors, rituximab and lenalidomide are underway. To date, activity of PI3K inhibitors appears to be most significant in lymphoid malignancies. Idelalisib, an inhibitor of the PI3K delta isoform, is FDA approved as a single agent for patients with follicular lymphoma and small lymphocytic lymphoma, and in combination with rituximab for recurrent chronic lymphocytic leukemia. Responses have been noted in mantle cell lymphoma, though durability is short. Numerous combination studies with chemotherapy and rituximab are ongoing. IPI-145 is an oral inhibitor of the delta and gamma isoforms of PI3K, and early studies have shown activity in both indolent B cell lymphomas as well as T cell histologies. The alpha and delta PI3K inhibitor copanlisib has also demonstrated early activity in a range of lymphoid histologies. The clinical activity and toxicity profile of PI3K inhibitors has suggested a significant potential role for these agents in the treatment of various lymphoproliferative cancers. Ongoing studies are evaluating potential biomarkers for response and resistance, as well as the development of rational combination approaches. Clinical findings suggest at this stage that targeting mTOR and PI3K represents a valuable therapeutic approach in lymphoma and that further investigation in this area will lead to further progress in improving patient outcomes.

Citation Format: John P. Leonard. PI3K and mTOR inhibitors in lymphoid malignancies: Clinical data. [abstract]. In: Proceedings of the AACR Special Conference: Targeting the PI3K-mTOR Network in Cancer; Sep 14-17, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(7 Suppl):Abstract nr IA28.

Phase I study of the anti-CD74 monoclonal antibody milatuzumab (hLL1) in patients with previously treated B-cell lymphomas

Milatuzumab (hLL1), a humanized anti-CD74 monoclonal antibody, has activity in preclinical non-Hodgkin lymphoma (NHL) models. We conducted a phase 1 trial in previously treated B-cell malignancies. Dose escalation included four planned dose levels (1.5, 4, 6 and 8 mg/kg) with milatuzumab given twice weekly for 6 weeks. After dose level 1, the schedule was changed to daily (Monday-Friday) for 10 days. Twenty-two patients were treated. The most common possibly related toxicities were infusion reaction, anemia, lymphopenia, neutropenia and thrombocytopenia. Three patients experienced dose-limiting toxicity (neutropenia, neutropenia, rash) at dose levels 1, 2 and 4, respectively. Eight patients had stable disease, with no objective responses. The serum half-life of milatuzumab was ∼2 h. In seven patients, In-111 imaging showed no clear evidence of tumor targeting. The short half-life may reflect CD74 rapid internalization and presence on extratumoral tissues; this antigen sink must be overcome to capitalize on the promising preclinical activity of the drug.