Lubomir Sokol

Results From a Pivotal, Open-Label, Phase II Study of Romidepsin in Relapsed or Refractory Peripheral T-Cell Lymphoma After Prior Systemic Therapy

PURPOSE Romidepsin is a structurally unique, potent class 1 selective histone deacetylase inhibitor. The primary objective of this international, pivotal, single-arm, phase II trial was to confirm the efficacy of romidepsin in patients with relapsed or refractory peripheral T-cell lymphoma (PTCL). PATIENTS AND METHODS Patients who were refractory to at least one prior systemic therapy or for whom at least one prior systemic therapy failed received romidepsin at 14 mg/m(2) as a 4-hour intravenous infusion on days 1, 8, and 15 every 28 days. The primary end point was the rate of complete response/unconfirmed complete response (CR/CRu) as assessed by an independent review committee. RESULTS Of the 131 patients enrolled, 130 had histologically confirmed PTCL by central review. The median number of prior systemic therapies was two (range, one to eight). The objective response rate was 25% (33 of 130), including 15% (19 of 130) with CR/CRu. Patient characteristics, prior stem-cell transplantation, number or type of prior therapies, or response to last prior therapy did not have an impact on response rate. The median duration of response was 17 months, with the longest response ongoing at 34+ months. Of the 19 patients who achieved CR/CRu, 17 (89%) had not experienced disease progression at a median follow-up of 13.4 months. The most common grade ≥ 3 adverse events were thrombocytopenia (24%), neutropenia (20%), and infections (all types, 19%). CONCLUSION Single-agent romidepsin induced complete and durable responses with manageable toxicity in patients with relapsed or refractory PTCL across all major PTCL subtypes, regardless of the number or type of prior therapies. Results led to US Food and Drug Administration approval of romidepsin in this indication.

A critical role for phosphatase haplodeficiency in the selective suppression of deletion 5q MDS by lenalidomide

Lenalidomide is the first karyotype-selective therapeutic approved for the treatment of myelodysplastic syndromes (MDS) owing to high rates of erythroid and cytogenetic response in patients with chromosome 5q deletion [del(5q)]. Although haploinsufficiency for the RPS14 gene and others encoded within the common deleted region (CDR) have been implicated in the pathogenesis of the del(5q) phenotype, the molecular basis of the karyotype specificity of lenalidomide remains unexplained. We focused our analysis on possible haplodeficient enzymatic targets encoded within the CDR that play key roles in cell-cycle regulation. We show that the dual specificity phosphatases, Cdc25C and PP2Acα, which are coregulators of the G2-M checkpoint, are inhibited by lenalidomide. Gene expression was lower in MDS and acute myeloid leukemia (AML) specimens with del(5q) compared with those with alternate karyotypes. Lenalidomide inhibited phosphatase activity either directly (Cdc25C) or indirectly (PP2A) with corresponding retention of inhibitory phospho-tyrosine residues. Treatment of del(5q) AML cells with lenalidomide induced G2 arrest and apoptosis, whereas there was no effect in nondel(5q) AML cells. Small interfering RNA (shRNA) suppression of Cdc25C and PP2Acα gene expression recapitulated del(5q) susceptibility to lenalidomide with induction of G2 arrest and apoptosis in both U937 and primary nondel(5q) MDS cells. These data establish a role for allelic haplodeficiency of the lenalidomide inhibitable Cdc25C and PP2Acα phosphatases in the selective drug sensitivity of del(5q) MDS.

Siltuximab, a Novel Anti–Interleukin-6 Monoclonal Antibody, for Castleman's Disease

PURPOSE Interleukin-6 (IL-6) has emerged as a key factor in the pathogenesis of the atypical lymphoproliferative disorder Castlemans disease (CD). Siltuximab is a new anti-IL-6, chimeric monoclonal antibody with potential therapeutic benefit in patients with CD. METHODS We report interim results from an open-label, dose-finding, seven-cohort, phase I study in which patients with symptomatic, multicentric or unresectable, unicentric CD received siltuximab at 1-, 2-, or 3-week intervals. The main efficacy end point of clinical benefit response (CBR) was defined as a composite of clinical and laboratory measures relevant to the management of CD. In addition, radiologic response was independently assessed by using modified Cheson criteria. RESULTS Eighteen (78%) of 23 patients (95% CI, 56% to 93%) achieved CBR, and 12 patients (52%) demonstrated objective tumor response. All 11 patients (95% CI, 72% to 100%) treated with the highest dose of 12 mg/kg achieved CBR, and eight patients (73%) achieved objective tumor response. Overall objective-response duration ranged from 44 to > or = 889 days, and one patient had complete response for > or = 318 days. Hemoglobin increased markedly in 19 patients (median increase, 2.1 g/dL; range, 0.2 to 4.7 g/dL) in the absence of transfusion or erythropoiesis-stimulating agents. No dose-limiting toxicity was reported, and only three patients had grade 3 or higher adverse events after a median exposure of 331 days (range, 1 to 1,148 days). CONCLUSION These interim results strongly suggest that siltuximab is an effective treatment with favorable safety for the management of CD. An additional study is planned to fully evaluate safety and efficacy at the recommended dose of 12 mg/kg every 3 weeks.

A Phase I, Open-Label Study of Siltuximab, an Anti–IL-6 Monoclonal Antibody, in Patients with B-cell Non-Hodgkin Lymphoma, Multiple Myeloma, or Castleman Disease

Purpose: To evaluate the safety and pharmacokinetics of siltuximab, an anti–interleukin-6 chimeric monoclonal antibody (mAb) in patients with B-cell non-Hodgkin lymphoma (NHL), multiple myeloma, or Castleman disease. Experimental Design: In an open-label, dose-finding, 7 cohort, phase I study, patients with NHL, multiple myeloma, or symptomatic Castleman disease received siltuximab 3, 6, 9, or 12 mg/kg weekly, every 2 weeks, or every 3 weeks. Response was assessed in all disease types. Clinical benefit response (CBR; composite of hemoglobin, fatigue, anorexia, fever/night sweats, weight, largest lymph node size) was also evaluated in Castleman disease. Results: Sixty-seven patients received a median of 16 siltuximab doses for a median of 8.5 (maximum 60.5) months; 29 were treated 1 year or longer. There was no dose-limiting toxicity, antibodies to siltuximab, or apparent dose–toxicity relationship. The most frequently reported possible drug-related adverse events were thrombocytopenia (25%), hypertriglyceridemia (19%), neutropenia (19%), leukopenia (18%), hypercholesterolemia (15%), and anemia (10%). None of these events led to dose delay/discontinuation except for neutropenia and thrombocytopenia (n = 1 each). No treatment-related deaths occurred. C-reactive protein (CRP) suppression was most pronounced at 12 mg/kg every 3 weeks. Mean terminal-phase half-life of siltuximab ranged 17.73 to 20.64 days. Thirty-two of 37 (86%) patients with Castleman disease improved in 1 or more CBR component; 12 of 36 evaluable Castleman disease patients had radiologic response [complete response (CR), n = 1; partial response (PR), n = 11], including 8 of 19 treated with 12 mg/kg; 2 of 14 (14%) evaluable NHL patients had PR; 2 of 13 (15%) patients with multiple myeloma had CR. Conclusion: No dose-related or cumulative toxicity was apparent across all disease indications. A dose of 12 mg/kg every 3 weeks was recommended on the basis of the high response rates in Castleman disease and the sustained CRP suppression. Randomized studies are ongoing in Castleman disease and multiple myeloma. Clin Cancer Res; 19(13); 3659–70. ©2013 AACR.

Phase 1/2 study of mogamulizumab, a defucosylated anti-CCR4 antibody, in previously treated patients with cutaneous T-cell lymphoma

This phase 1/2 study evaluated the efficacy of mogamulizumab, a defucosylated, humanized, anti-CC chemokine receptor 4 monoclonal antibody, in 41 pretreated patients with cutaneous T-cell lymphoma. No dose-limiting toxicity was observed and the maximum tolerated dose was not reached in phase 1 after IV infusion of mogamulizumab (0.1, 0.3, and 1.0 mg/kg) once weekly for 4 weeks followed by a 2-week observation. In phase 2, patients were dosed with 1.0 mg/kg mogamulizumab according to the same schedule for the first course followed by infusion every 2 weeks during subsequent courses until disease progression. The most frequent treatment-emergent adverse events were nausea (31.0%), chills (23.8%), headache (21.4%), and infusion-related reaction (21.4%); the majority of events were grade 1/2. There were no significant hematologic effects. Among 38 evaluable patients, the overall response rate was 36.8%: 47.1% in Sézary syndrome (n = 17) and 28.6% in mycosis fungoides (n = 21). Eighteen of 19 (94.7%) patients with ≥B1 blood involvement had a response in blood, including 11 complete responses. Given the safety and efficacy of mogamulizumab, phase 3 investigation of mogamulizumab is warranted in cutaneous T-cell lymphoma patients. This trial was registered at www.clinicaltrials.gov as #NCT00888927.

Rosai-Dorfman Disease: Tumor Biology, Clinical Features, Pathology, and Treatment

BACKGROUND Rosai-Dorfman disease (RDD) is a rare, nonmalignant clinical entity characterized by a group of clinical symptoms and characteristic pathological features. METHODS Articles that reviewed tumor biology, clinical features, pathology, and treatment for RDD were identified in a search of the literature for the years 1990 to 2014. The results from this body of literature were reviewed and summarized. RESULTS Patients with RDD generally present with massive, painless cervical lymphadenopathy, fevers, and elevated inflammatory markers. Extranodal disease is typical, with the most common sites being the skin and the central nervous system. Rarely, the gastrointestinal tract is involved. Immunohistochemistry remains the mainstay of diagnosis with S100 and CD68 positive cells while CD1a will be negative of involved histiocytes. Histologically, the disease shows the classical characteristic finding of emperipolesis. Many patients do not require treatment; however, surgical resection remains the mainstay of treatment for symptomatic disease. The role of steroids, chemotherapy, and radiation therapy continue to be based on small case series and case reports. CONCLUSIONS RDD has a variable clinical presentation; therefore, a high degree of suspicion and a thorough pathological review are necessary to diagnose this rare clinical entity. Although some patients will experience spontaneous resolution, others may require surgical resection or steroid therapy and radiation or chemotherapy. Given the rarity of the disease and the lack of a clear therapeutic pathway, referring patients to a tertiary center is recommended for confirming the diagnosis and treatment considerations.

Reduced SMAD7 Leads to Overactivation of TGF-β Signaling in MDS that Can Be Reversed by a Specific Inhibitor of TGF-β Receptor I Kinase

Even though myelodysplastic syndromes (MDS) are characterized by ineffective hematopoiesis, the molecular alterations that lead to marrow failure have not been well elucidated. We have previously shown that the myelosuppressive TGF-β pathway is constitutively activated in MDS progenitors. Because there is conflicting data about upregulation of extracellular TGF-β levels in MDS, we wanted to determine the molecular basis of TGF-β pathway overactivation and consequent hematopoietic suppression in this disease. We observed that SMAD7, a negative regulator of TGF-β receptor I (TBRI) kinase, is markedly decreased in a large meta-analysis of gene expression studies from MDS marrow-derived CD34(+) cells. SMAD7 protein was also found to be significantly decreased in MDS marrow progenitors when examined immunohistochemically in a bone marrow tissue microarray. Reduced expression of SMAD7 in hematopoietic cells led to increased TGF-β-mediated gene transcription and enhanced sensitivity to TGF-β-mediated suppressive effects. The increased TGF-β signaling due to SMAD7 reduction could be effectively inhibited by a novel clinically relevant TBRI (ALK5 kinase) inhibitor, LY-2157299. LY-2157299 could inhibit TGF-β-mediated SMAD2 activation and hematopoietic suppression in primary hematopoietic stem cells. Furthermore, in vivo administration of LY-2157299 ameliorated anemia in a TGF-β overexpressing transgenic mouse model of bone marrow failure. Most importantly, treatment with LY-2157199 stimulated hematopoiesis from primary MDS bone marrow specimens. These studies demonstrate that reduction in SMAD7 is a novel molecular alteration in MDS that leads to ineffective hematopoiesis by activating of TGF-β signaling in hematopoietic cells. These studies also illustrate the therapeutic potential of TBRI inhibitors in MDS.

Lenalidomide Promotes p53 Degradation by Inhibiting MDM2 Auto-ubiquitination in Myelodysplastic Syndrome with Chromosome 5q Deletion

Allelic deletion of the RPS14 gene is a key effector of the hypoplastic anemia in patients with myelodysplastic syndrome (MDS) and chromosome 5q deletion (del(5q)). Disruption of ribosome integrity liberates free ribosomal proteins to bind to and trigger degradation of mouse double minute 2 protein (MDM2), with consequent p53 transactivation. Herein we show that p53 is overexpressed in erythroid precursors of primary bone marrow del(5q) MDS specimens accompanied by reduced cellular MDM2. More importantly, we show that lenalidomide (Len) acts to stabilize MDM2, thereby accelerating p53 degradation. Biochemical and molecular analyses showed that Len inhibits the haplodeficient protein phosphatase 2A catalytic domain alpha (PP2Acα) phosphatase resulting in hyperphosphorylation of inhibitory serine-166 and serine-186 residues on MDM2, and displaces binding of RPS14 to suppress MDM2 autoubiquitination whereas PP2Acα overexpression promotes drug resistance. Bone marrow specimens from del(5q) MDS patients resistant to Len overexpressed PP2Acα accompanied by restored accumulation of p53 in erythroid precursors. Our findings indicate that Len restores MDM2 functionality in the 5q- syndrome to overcome p53 activation in response to nucleolar stress, and therefore may warrant investigation in other disorders of ribosomal biogenesis.

Human immunodeficiency virus (HIV)-negative plasmablastic lymphoma: A single institutional experience and literature review

Plasmablastic lymphoma (PBL) is a rare aggressive B-cell lymphoproliferative disorder. HIV-negative PBL has not been extensively reported. Nine HIV-negative PBL patients evaluated at Moffitt Cancer Center were studied. Eight patients had extranodal diseases. All patients were treated with CHOP or hyper-CVAD. Responses were observed in 8 cases (7 complete, 1 partial responses). Four patients underwent consolidation with autologous hematopoietic stem cell transplant (HSCT) in first complete remission (CR1). At median follow-up of 23.9 months, 7 patients were alive and 5 were disease-free. Aggressive induction chemotherapy and consolidation with autologous HSCT in CR1 might be considered for patients with HIV-negative PBL.

Identification of a risk dependent microRNA expression signature in myelodysplastic syndromes

The myelodysplastic syndromes (MDS) display both haematological and biological heterogeneity with variable leukaemia potential. MicroRNAs play an important role in tumour suppression and the regulation of self‐renewal and differentiation of haematopoietic progenitors. Using a microarray platform, we evaluated microRNA expression from 44 patients with MDS and 17 normal controls. We identified a thirteen microRNA signature with statistically significant differential expression between normal and MDS specimens (P < 0·01), including down‐regulation of members of the leukaemia‐associated MIRLET7 family. A unique signature consisting of 10 microRNAs was closely associated with International Prognostic Scoring System (IPSS) risk category permitting discrimination between lower (Low/Intermediate‐1) and higher risk (Intermediate‐2/High) disease (P < 0·01). Selective overexpression of MIR181 family members was detected in higher risk MDS, indicating pathogenetic overlap with acute myeloid leukaemia. Survival analysis of an independent cohort of 22 IPSS lower risk MDS patients revealed a median survival of 3·5 years in patients with high expression of MIR181 family compared to 9·3 years in patients with low MIR181 expression (P = 0·002). Our pilot study suggested that analysis of microRNA expression profile offers diagnostic utility, and provide pathogenetic and prognostic discrimination in MDS.