Prospective subgroup analyses of the randomized MCL‐002 (SPRINT) study: lenalidomide versus investigator's choice in relapsed or refractory mantle cell lymphoma

In the mantle cell lymphoma (MCL)‐002 study, lenalidomide demonstrated significantly improved median progression‐free survival (PFS) compared with investigator's choice (IC) in patients with relapsed/refractory MCL. Here we present the long‐term follow‐up data and results of preplanned subgroup exploratory analyses from MCL‐002 to evaluate the potential impact of demographic factors, baseline clinical characteristics and prior therapies on PFS. In MCL‐002, patients with relapsed/refractory MCL were randomized 2:1 to receive lenalidomide (25 mg/day orally on days 1–21; 28‐day cycles) or single‐agent IC therapy (rituximab, gemcitabine, fludarabine, chlorambucil or cytarabine). The intent‐to‐treat population comprised 254 patients (lenalidomide, n = 170; IC, n = 84). Subgroup analyses of PFS favoured lenalidomide over IC across most characteristics, including risk factors, such as high MCL International Prognostic Index score, age ≥65 years, high lactate dehydrogenase (LDH), stage III/IV disease, high tumour burden, and refractoriness to last prior therapy. By multivariate Cox regression analysis, factors associated with significantly longer PFS (other than lenalidomide treatment) included normal LDH levels (P < 0·001), nonbulky disease (P = 0·045), <3 prior antilymphoma treatments (P = 0·005), and ≥6 months since last prior treatment (P = 0·032). Overall, lenalidomide improved PFS versus single‐agent IC therapy in patients with relapsed/refractory MCL, irrespective of many demographic factors, disease characteristics and prior treatment history.     

Longer‐term follow‐up and outcome by tumour cell proliferation rate (Ki‐67) in patients with relapsed/refractory mantle cell lymphoma treated with lenalidomide on MCL‐001(EMERGE) pivotal trial

Patients with mantle cell lymphoma (MCL) generally respond to first‐line immunochemotherapy, but often show chemoresistance upon subsequent relapses, with poor outcome. Several studies of the immunomodulator, lenalidomide, have demonstrated its activity in MCL including the MCL‐001 study in relapsed/refractory patients who had failed defined prior therapies of anthracyclines or mitoxantrone, cyclophosphamide, rituximab and also bortezomib. We present here the long‐term efficacy follow‐up of the prospective phase II MCL‐001 study (N = 134), including new exploratory analyses with baseline Ki‐67 (MIB1), a biological marker of tumour proliferation. With longer follow‐up, lenalidomide showed a 28% overall response rate [ORR; 8% complete response (CR)/CR unconfirmed (CRu)]. Median duration of response (DOR), progression‐free survival and overall survival were 16·6, 4·0 and 20·9 months, respectively. Myelosuppression continued to be the most common grade 3/4 toxicity. Several studies of MCL patients treated with chemotherapy, rituximab and bortezomib have shown an inverse association between survival and Ki‐67. Ki‐67 data in 81/134 MCL‐001 patients showed similar ORRs in both low (<30% or <50%) versus high (≥30% or ≥50%) Ki‐67–expressing groups, yet lower Ki‐67 levels demonstrated superior CR/CRu, DOR and survival outcomes. Overall, lenalidomide showed durable efficacy with a consistent safety profile in heavily pretreated, relapsed/refractory MCL post‐bortezomib.     

Single‐agent lenalidomide in relapsed/refractory mantle cell lymphoma: results from a UK phase II study suggest activity and possible gender differences

We present data from a phase II study investigating a novel treatment strategy for relapsed/refractory mantle cell lymphoma (MCL). Twenty‐six patients received lenalidomide 25 mg/d (days 1–21 of a 28‐d cycle) for up to 6 cycles followed by low‐dose maintenance lenalidomide (15 mg) in responding patients. Eight patients achieved complete or partial response to give an overall response rate of 31% with median response duration of 22·2 months [95% confidence interval (CI) 0·0–53·6] and median progression‐free survival (PFS) of 3·9 months (95% CI 0·0–11·1). An additional six patients (23%) achieved stable disease. Eleven patients received maintenance with median PFS of 14·6 months (95% CI 7·3–21·9). Correlative studies showed that peripheral T and Natural Killer (NK) cells increased in responding patients by 40–60% over the first 6 cycles with an initial dip in NK cells suggestive of tumour infiltration. Peripheral regulatory T cells were increased in MCL patients (P = 0·001) and expanded further following lenalidomide. Sequential plasma analysis showed increased IL12 p40 and IL7 alongside decreased MMP9, IL10, and adiponectin. Finally, a significant correlation (P = 0·02) between gender and response suggested that female MCL patients were more sensitive to lenalidomide than males. In summary, we confirm the activity, safety and immunomodulatory properties of lenalidomide in MCL and highlight its potential as a low‐dose maintenance agent.     

A functional mammalian display screen identifies rare antibodies that stimulate NK cell–mediated cytotoxicity

Therapies that boost the antitumor immune response have shown a great deal of success. Although most of these therapies have focused on enhancing T cell functions, there is a growing interest in developing therapies that can target other immune cell subsets. Like T cells, natural killer (NK) cells are cytotoxic effector cells that play a key role in the antitumor response. To advance the development of NK-based therapies, we developed a functional screen to rapidly identify antibodies that can activate NK cells. We displayed antibodies on a mammalian target cell line and probed their ability to stimulate NK cell–mediated cytotoxicity. From this screen, we identified five antibodies that bound with high affinity to NK cells and stimulated NK cell–mediated cytotoxicity and interferon-γ (IFN-γ) secretion. We demonstrate that these antibodies can be further developed into bispecific antibodies to redirect NK cell–mediated cytotoxicity toward CD20+ B cell lymphoma cells and HER2+ breast cancer cells. While antibodies to two of the receptors, CD16 and NCR1, have previously been targeted as bispecific antibodies to redirect NK cell–mediated cytotoxicity, we demonstrate that bispecific antibodies targeting NCR3 can also potently activate NK cells. These results show that this screen can be used to directly identify antibodies that can enhance antitumor immune responses.

Cancer immunotherapies have garnered a great deal of success over the last decade. Much of this success has been driven by the development of antibody-based therapeutics that redirect and enhance the cytotoxic potential of CD8+ T cells via immune checkpoint blockade or CD3/T cell receptor (TCR) complex stimulation. Like CD8+ T cells, natural killer (NK) cells are cytotoxic effector cells that mediate antitumor responses (1–3). They play a key role in tumor immunosurveillance and are able to identify and remove target cells by recognizing stress-induced ligands that are frequently overexpressed on cancer cells. NK cells are also known to perform antibody-dependent cellular cytotoxicity (ADCC), a mechanism that is used by multiple current therapeutic monoclonal antibodies to eradicate tumor cells (4–6). Given the crucial role that NK cells play in tumor immunosurveillance, the identification of novel immunotherapies that can target and redirect NK cell cytotoxicity merits further investigation.Whereas all T cells express the CD3/TCR complex that can be exploited by immunomodulatory molecules to redirect T cell activity, NK cells express multiple activating, costimulatory, and inhibitory receptors that govern NK cell activity (7, 8). Moreover, the NK cell repertoire is highly diverse, and the expression of these activating and inhibitory receptors among different cell subsets varies greatly within and among individuals (9, 10). These factors make it difficult to develop antibodies that can recruit and stimulate NK cells. Here, we report an approach to directly evaluate the ability of a curated set of antibodies to induce NK cell–mediated cytotoxicity.We couple a mammalian display screen to a next generation sequencing (NGS) readout to characterize antibodies that bind to and activate NK cells. Antibodies were selected against six NK cell receptors from an antigen-binding fragment (Fab)-phage library that was based on the trastuzumab scaffold and were displayed on a target cell line to generate a mammalian display library. NK cells have the innate ability to recognize and kill unhealthy cells. We reasoned that an antibody against an NK cell surface protein that was displayed on a target cell could drive the interaction between an NK cell and a target cell. If the antibody was also able to activate NK cells, then the cell displaying the antibody would be killed and deselected. All of our antibodies are constructed on the same scaffold, allowing the use of the same set of primers to amplify and sequence the complementarity determining region (CDR) H3 of each clone. Thus, we rationalized that we should be able to screen these antibodies in a pooled manner and quantify the depletion of specific antibody clones through NGS of CDR H3. Indeed, antibody binders that were depleted in our functional screen were able to stimulate NK cell cytotoxicity and interferon-γ (IFN-γ) secretion. We found that the most potent stimulators of NK cell–mediated cytotoxicity were high-affinity binders to previously identified activating NK receptors, like CD16, NCR1, and NCR3, and that binding to an upregulated NK cell surface protein, TNFSF4, or costimulator NK receptors, TNFRSF9 and CD244, were unable to stimulate NK activity. These activating antibodies were applied to the generation of bispecific antibodies to redirect NK cells toward CD20+ B cell lymphoma cells and HER2+ breast cancer cells. We believe this method can facilitate the discovery of rare antibodies that can stimulate immune cell activation and promote the design of immunotherapies.     

Therapy refractory angioimmunoblastic T‐cell lymphoma in complete remission with lenalidomide

The prognosis of therapy refractory angioimmunoblastic lymphoma (AITL) is very poor. In this report we describe a patient with AITL refractory to 2 lines of chemotherapy. He was treated with lenalidomide 15 mg continuously and prednisone. After 2 yr follow‐up, the patient has no detectable disease. Lenalidomide was well tolerated without side‐effects. Lenalidomide even in lower dosed combined with steroids can induce complete responses in patients with refractory AITL.     

Natural killer (NK) cell leukaemia in a patient with a B cell non‐Hodgkin’s lymphoma

Summary We describe a 74‐year‐old woman with the diagnosis of natural killer (NK)‐cell leukaemia and autoimmune pathology. Four years previously, a diffuse large B cell non‐Hodgkin’s lymphoma had been diagnosed and treated effectively. Although NK‐cell leukaemia has been thought to be a distinct highly aggressive clinicopathological entity, our case shows no further evolution at the present time. As far as we know, this association has not been previously described in the literature.     

Salvage treatment with lenalidomide and dexamethasone in relapsed/refractory mantle cell lymphoma: clinical results and effects on microenvironment and neo-angiogenic biomarkers

Background

Preclinical studies have highlighted the activity of lenalidomide in mantle cell lymphoma and its anti-proliferative synergy with dexamethasone.

Design and Methods

In this prospective, multicenter, phase II study, patients with relapsed/refractory mantle cell lymphoma who were not eligible for, or had relapsed after, intensive treatments received lenalidomide 25 mg/day (days 1–21 of each 28-day cycle) and dexamethasone (40 mg/day on days 1, 8, 15, and 22) for up to 12 months.

Results

The primary end-points, overall and complete response rates, were achieved by 17 of 33 (52%; 95% confidence interval [CI], 35–68%) and 8 of 33 patients (24%; 95% CI, 13–41%), respectively, by the end of treatment. Fifteen patients (45%) discontinued treatment prematurely, 13 due to lack of response. The median progression-free and overall survival were 12 months (95% CI, 5–19 months) and 20 months (95% CI, 12 months to not estimable), respectively. Treatment resulted in a significant increase in microvessel density (P=0.033) and non-significant increases in macrophage and natural killer cell counts, while serum levels of neoangiogenic factors did not change significantly. Grade 3/4 adverse events were neutropenia (53%), leukopenia (25%), thrombocytopenia (22%), infections (12%), and febrile neutropenia (12%).

Conclusions

These results confirm a favorable safety and activity profile of lenalidomide in relapsed/refractory mantle cell lymphoma. The contribution of dexamethasone in achieving these results is unclear because of its possible detrimental effect on the immune activation generated by lenalidomide and a higher risk of developing infectious complications. (clinicaltrials.gov identifier: NCT00786851).     

Front‐line management of indolent non‐Hodgkin lymphoma in Australia. Part 2: mantle cell lymphoma and marginal zone lymphoma

Mantle cell lymphoma (MCL) and the marginal zone lymphoma (MZL) subtypes (nodal MZL, extra‐nodal MZL of mucosa‐associated lymphoid tissue (MALT lymphoma) and splenic MZL) are uncommon lymphoma subtypes, accounting for less than 5–10% of all non‐Hodgkin lymphoma. The evidence base for therapy is therefore limited and enrolment into clinical trials is preferred. Outcomes for patients with MCL have been steadily improving mainly due to the adoption of more intense strategies in younger patients, the use of rituximab maintenance and the recent introduction of bendamustine in older patients. MZL is a more heterogeneous group of cancer with both nodal, extra‐nodal and splenic subtypes. Extranodal MZL may be associated with autoimmune or infectious aetiologies, and can respond to eradication of the causative pathogen. Proton pump inhibitor plus dual antibiotics in Helicobacter pylori positive gastric MALT lymphoma is curative in many patients. Watchful waiting is appropriate in most patients with asymptomatic advanced stage disease, which tends to behave in a particularly indolent manner. Other options for symptomatic disease include splenectomy, chemoimmunotherapy with rituximab and, more recently, targeted therapies.     

Lenalidomide oral monotherapy produces a high response rate in patients with relapsed or refractory mantle cell lymphoma

Mantle cell lymphoma (MCL) is an aggressive non-Hodgkin lymphoma with a poor prognosis following first relapse. We present a subgroup analysis of an open-label phase II trial investigating the efficacy and safety of lenalidomide in patients with relapsed or refractory MCL. Oral lenalidomide 25 mg was self-administered once daily on days 1–21 every 28 d for up to 52 weeks, according to tolerability or until disease progression. The primary endpoint was overall response rate (ORR) and secondary endpoints were duration of response, progression-free survival (PFS) and safety. Among 15 patients with MCL with a median disease duration of 5·1 years and a median of four prior treatments, the ORR was 53%. Three patients (20%) had a complete response and 5 (33%) had a partial response. The median duration of response was 13·7 months and median PFS was 5·6 months. Four of five patients who relapsed after transplantation and two of five patients who previously received bortezomib responded to lenalidomide. The most common grade 4 adverse event was thrombocytopenia (13%) and the most common grade 3 adverse events were neutropenia (40%), leucopenia (27%) and thrombocytopenia (20%). In conclusion, oral lenalidomide monotherapy is well tolerated and active in relapsed or refractory MCL.     

Downregulation of BCL2 by AT‐101 enhances the antileukaemic effect of lenalidomide both by an immune dependant and independent manner

Over‐expression of anti‐apoptotic BCL2 has been reported in chronic lymphocytic leukaemia (CLL), but targeting BCL2 alone did not yield appreciable clinical results. However, it was demonstrated that BCL2 inhibitors enhanced the clinical efficacy of chemo and immunotherapeutics. Lenalidomide, an immunomodulator, is clinically effective in CLL and can enhance the anti‐CLL effects of CD20 targeting monoclonal antibody, rituximab. Here, we investigated the mechanism of immune‐directed killing of lenalidomide in CLL and evaluated if concurrent targeting of CD20 and BCL2 can enhance this effect. In vitro treatment with lenalidomide enhanced the antibody‐mediated cellular cytotoxicity (ADCC) directed by rituximab in autologous leukaemic cells. Furthermore, peripheral blood mononuclear cells obtained from patients after treatment with lenalidomide and rituximab showed increased ADCC in vitro versus control (pre‐treatment sample). This effect was further enhanced with pre‐treatment of tumour cells with AT‐101 (a BH3 mimetic that functions as BCL2 antagonist). Our data suggest that AT‐101 in combination with lenalidomide can potentially be an effective therapeutic regimen for CLL.     

Combination lenalidomide-rituximab immunotherapy activates anti-tumour immunity and induces tumour cell death by complementary mechanisms of action in follicular lymphoma

Chemotherapy plus rituximab has been the mainstay of treatment for follicular lymphoma (FL) for two decades but is associated with immunosuppression and relapse. In phase 2 studies, lenalidomide combined with rituximab (R²) has shown clinical synergy in front-line and relapsed/refractory FL. Here, we show that lenalidomide reactivated dysfunctional T and Natural Killer (NK) cells ex vivo from FL patients by enhancing proliferative capacity and T-helper cell type 1 (Th1) cytokine release. In combination with rituximab, lenalidomide improved antibody-dependent cellular cytotoxicity in sensitive and chemo-resistant FL cells, via a cereblon-dependent mechanism. While single-agent lenalidomide and rituximab increased formation of lytic NK cell immunological synapses with primary FL tumour cells, the combination was superior and correlated with enhanced cytotoxicity. Immunophenotyping of FL patient samples from a phase 3 trial revealed that R² treatment increased circulating T- and NK-cell counts, while R-chemotherapy was associated with reduced cell numbers. Finally, using an in vitro model of myeloid differentiation, we demonstrated that lenalidomide caused a reversible arrest in neutrophil maturation that was distinct from a cytotoxic chemotherapeutic agent, which may help explain the lower rates of neutropenia observed with R² versus R-chemotherapy. Taken together, we believe these data support a paradigm shift in the treatment of FL – moving from combination immunochemotherapy to chemotherapy-free immunotherapy.     

Abnormal serum free light chain ratio predicts poor overall survival in mantle cell lymphoma

Serum free light Chain (sFLC) ratios have been correlated with survival outcomes in Hodgkin and non‐Hodgkin lymphoma subtypes. This study was undertaken to investigate the prognostic impact of abnormal sFLC ratios in mantle cell lymphoma (MCL). two patient cohorts were analysed for sFLC parameters: a preliminary retrospective cohort and a uniformly treated cohort of 20 relapsed/refractory MCL patients, enrolled in a phase II clinical trial of single agent lenalidomide treatment. 52% of patients had an abnormality of one or more sFLC parameter (71% of the first cohort and 40% of the second cohort). In cohort two, a high baseline SFLC ratio correlated with poorer overall survival (OS) compared to a low/normal ratio (median OS: 1·4 months vs. 19 months respectively; P = 0·001). For patients presenting with an elevated sFLC ratio at trial entry a rise of >35% in the sFLC ratio correlated with disease progression and a sFLC ratio of >2× normal at trial entry correlated with aggressive disease. These data are the first to show a clear clinical correlation between sFLC ratios and survival outcomes in a uniformly treated cohort of MCL patients. We suggest that these markers may be useful in managing patients with MCL in the future.     

Autoantibodies against the specific epitope of human tropomyosin(s) detected by a peptide based enzyme immunoassay in sera of patients with ulcerative colitis show antibody dependent cell mediated cytotoxicity against HLA-DPw9 transfected L cells

BACKGROUND AND AIMS: Recent studies suggest that tropomyosin (TM) may act as a putative autoantigen in ulcerative colitis (UC). Recently, we identified, by computer homology analysis, a specific peptide (HIAEDADRK) in human TM that can bind to HLA-DPw9. The aim of this study was to investigate the presence of autoantibodies against this peptide in UC. METHODS: Antibodies were measured by ELISA with a synthetic peptide in 20 healthy volunteers, 48 patients with UC, 26 with Crohn's disease (CD), eight with primary sclerosing cholangitis (PSC), and six with primary biliary cirrhosis (PBC). The functional significance of antibodies was investigated by antibody dependent cell mediated cytotoxicity (ADCC) against DPw9 transfected L cells using a standard (51)Cr release assay. RESULTS: Optical density values (mean (SD)) of sera from patients with UC (1.40 (0. 52)) and PSC (1.65 (0.12)) were significantly higher than those from healthy volunteers (0.32 (0.28)) (p<0.05), CD (0.50 (0.34)) (p<0.05) and PBC (0.14 (0.09)) (p<0.05). Values in UC decreased with clinical improvement. The ADCC activity of UC sera correlated well with antibody titre against this synthetic peptide. CONCLUSIONS: Anti-TM antibody was detected in UC sera by a specific peptide based ELISA with high reproducibility. This peptide may be an antigenic epitope of TM involved in the immunopathogenesis of UC and, perhaps, PSC.     

Activity and safety of combined rituximab with chlorambucil in patients with mantle cell lymphoma

We evaluated the combination of rituximab with chlorambucil in patients with mantle cell lymphoma (MCL) not eligible for aggressive therapy. Fourteen patients (male/female: 9/5) were included (two newly diagnosed, 12 relapsed/refractory). The toxicities were neutropenia, thrombopenia and infection. Nine (64%) patients responded; five (36%) achieved complete remission and four (29%) achieved partial remission. The median progression-free survival for responders was 26 months (95% CI, 4-48). Marrow polymerase chain reaction negativity was attained in seven responders. These results suggest that this schedule may have notable antitumour activity in patients with MCL, including patients in relapse after autologous stem cell transplantation.     

Characterization of ibrutinib‐sensitive and ‐resistant mantle lymphoma cells

Ibrutinib inhibits Bruton tyrosine kinase (BTK), a key component of early B‐cell receptor (BCR) signalling pathways. A multicentre phase 2 trial of ibrutinib in patients with relapsed/refractory mantle cell lymphoma (MCL) demonstrated a remarkable response rate. However, approximately one‐third of patients have primary resistance to the drug while other patients appear to lose response and develop secondary resistance. Understanding the molecular mechanisms underlying ibrutinib sensitivity is of paramount importance. In this study, we investigated cell lines and primary MCL cells that display differential sensitivity to ibrutinib. We found that the primary cells display a higher BTK activity than normal B cells and MCL cells show differential sensitivity to BTK inhibition. Genetic knockdown of BTK inhibits the growth, survival and proliferation of ibrutinib‐sensitive but not resistant MCL cell lines, suggesting that ibrutinib acts through BTK to produce its anti‐tumour activities. Interestingly, inhibition of ERK1/2 and AKT, but not BTK phosphorylation per se, correlates well with cellular response to BTK inhibition in cell lines as well as in primary tumours. Our study suggests that, to prevent primary resistance or to overcome secondary resistance to BTK inhibition, a combinatory strategy that targets multiple components or multiple pathways may represent the most effective approach.