Predictors of Lenalidomide Refractory Relapse Timing With Newly Diagnosed Multiple Myeloma: A FIRST Trial Subanalysis.

INTRODUCTION/BACKGROUND: Multiple myeloma (MM) is considered an incurable cancer. Patients with newly diagnosed MM (NDMM) are at risk for relapse within 1 year of frontline therapy. The immunomodulatory agent lenalidomide combined with dexamethasone (Rd) may be used as treatment for NDMM or relapsed MM, including in patients ineligible for autologous stem cell transplant. PATIENTS: This subanalysis of the phase III FIRST trial characterized patients with transplant-ineligible NDMM who experienced relapse while receiving Rd therapy by relapse timing (early [<12 months] versus late [≥12 months]) and type (CRAB vs. non-CRAB). METHODS: The Kaplan-Meier product limit method was used to estimate time-to-event endpoints, including progression-free survival (PFS) and overall survival (OS). Factors associated with the odds of late relapse were identified by logistic regression with univariate and multivariate analyses using a binary outcome (relapse at <12 vs. ≥12 months) in patient-, disease-, and treatment-specific baseline variables. RESULTS: Patients with early refractory relapse had functionally high-risk disease and inferior outcomes. In patients with early relapse versus those with late relapse, median OS (95% CI) was 26.8 months (21.9-32.8) versus 63.9 months (57.0-78.0), median OS from disease progression to death was 19.9 months (16.0-25.5) versus 36.4 months (27.9-47.0), and median PFS from randomization to second progression was 19.1 months (17.3-22.5) versus 42.1 months (37.4-44.9). Lactate dehydrogenase, baseline ß2 microglobulin, and myeloma subtype were shown to predict time to relapse. CONCLUSIONS: Clinicians could use these factors to consider more aggressive treatment regimens for those at highest risk of early relapse.

A simplified frailty scale predicts outcomes in transplant-ineligible patients with newly diagnosed multiple myeloma treated in the FIRST (MM-020) trial.

Patients with multiple myeloma are generally older and vary in fitness levels, which may influence the clinical benefit of treatment. Patients from the large, phase 3 FIRST trial in newly diagnosed multiple myeloma (NDMM) were retrospectively investigated to determine outcomes based on frailty using scores for age, Charlson Comorbidity Index (CCI), and Eastern Cooperative Oncology Group performance status (ECOG PS), instead of the EQ-5D quality-of-life questionnaire, as previously reported. ECOG PS (n = 1618) was investigated in frailty groups: frail (49%) and nonfrail (51%). Frail patients experienced worse progression-free and overall survival vs nonfrail patients. Prognostic assessment was improved when combining frailty and International Staging System stage (I/II vs III). Frail patients had a higher risk of developing grade 3/4 treatment-emergent adverse events. Treatment effects observed in the FIRST trial were confirmed per frailty group and per frailty and ISS group. The use of this ECOG PS-containing frailty scale as a predictive measure of clinical outcomes in patients with transplant-ineligible NDMM is supported by data from the FIRST trial. This score, based on age, CCI, and ECOG PS, can be easily replicated and may help design future myeloma studies in frail or nonfrail elderly patients.

Impact of post-ASCT maintenance therapy on outcomes in patients with newly diagnosed multiple myeloma in Connect MM.

Autologous stem cell transplantation (ASCT) followed by lenalidomide maintenance therapy is the standard of care for transplant-eligible patients with newly diagnosed multiple myeloma (NDMM). Clinical trials show progression-free survival (PFS) benefits, with some studies (Cancer and Leukemia Group [CALGB] trial and meta-analysis) also showing overall survival (OS) benefits, but applicability to real-world clinical settings is unclear. Using data from Connect MM, the largest US-based observational registry of NDMM patients, we analyzed effects of maintenance therapy on long-term outcomes in 1450 treated patients enrolled from 2009 to 2011. Patients who received induction therapy and ASCT (n = 432) were analyzed from 100 days post-ASCT (data cut 7 January 2016): 267 received maintenance (80% lenalidomide-based [of whom 88% received lenalidomide monotherapy]); 165 did not. Lenalidomide maintenance improved median PFS and 3-year PFS rate vs no maintenance (50.3 vs 30.8 months [hazard ratio (HR), 0.62; 95% confidence interval (CI), 0.46-0.82; P < .001] and 56% vs 42%, respectively). Improvements in median OS and 3-year OS rate were associated with lenalidomide maintenance vs no maintenance (not reached in either group [HR, 0.54; 95% CI, 0.36-0.83; P = .005] and 85% vs 70%, respectively). Five hematologic serious adverse events were reported with lenalidomide maintenance (pancytopenia [n = 2], febrile neutropenia, anemia, and thrombocytopenia [n = 1 each]) and 1 with no maintenance (thrombocytopenia). Second primary malignancies occurred at rates of 1.38 and 2.19 events per patient-year in lenalidomide maintenance and no maintenance groups, respectively. Survival benefits associated with lenalidomide maintenance previously demonstrated in clinical trials were observed in this community-based Connect MM Registry.

TIG3: a regulator of type I transglutaminase activity in epidermis.

Keratinocytes undergo a process of terminal cell differentiation that results in the construction of a multilayered epithelium designed to produce a structure that functions to protect the body from dehydration, abrasion and infection. These protective properties are due to the production of a crosslinked layer of protein called the cornified envelope. Type I transglutaminase (TG1), an enzyme that catalyzes the formation of epsilon-(gamma-glutamyl)lysine bonds, is the key protein responsible for generation of the crosslinks. The mechanisms that lead to activation of transglutaminase during terminal differentiation are not well understood. We have identified a protein that interacts with TG1 and regulates its activity. This protein, tazarotene-induced gene 3 (TIG3), is expressed in the differentiated layers of the epidermis and its expression is associated with transglutaminase activation and cornified envelope formation. We describe a novel mechanism whereby TIG3 regulates TG1 activity.

Localization of the TIG3 transglutaminase interaction domain and demonstration that the amino-terminal region is required for TIG3 function as a keratinocyte differentiation regulator.

Tazarotene-induced gene 3 (TIG3) regulates keratinocyte terminal differentiation by activating type I transglutaminase (TG1). TIG3 consists of an amino-terminal (N-terminal) segment, that encodes several conserved motifs, and a carboxy-terminal (C-terminal) membrane-anchoring domain. By producing a series of truncation mutants that remove segments of the N-terminal region, and monitoring the ability of each mutant to co-precipitate TG1, function as a TG1 substrate, or functionally localize with TG1 in cells, we show that the TIG3 domain that interacts with TG1 is located within a TIG3 segment spanning amino acids 112-164. Although they bind TG1, TIG3 mutants lacking the conserved N-terminal region drive apoptosis-like cell death characterized by cell rounding, membrane blebbing, cytochrome c release, procaspase-3 and poly(ADP-ribose)polymerase (PARP) cleavage, and reduced p53 and p21 levels. Compared with TIG3, these truncated mutants have an increased tendency to associate with membranes. A mutant lacking the C-terminal membrane-anchoring domain is inactive. These findings suggest that TIG3 interaction with TG1 does not require the N-terminal conserved domains, that the TIG3 N-terminal region is required for TIG3-dependent keratinocyte differentiation, that its removal converts TIG3 into a proapoptotic protein, and that this change in action of TIG3 is associated with an intracellular redistribution.

A novel transglutaminase activator forms a complex with type 1 transglutaminase.

Type I transglutaminase is a plasma membrane-anchored intracellular protein-protein crosslinking enzyme that is responsible for assembly of the keratinocyte cornified envelope during terminal keratinocyte differentiation. We recently described a novel protein, TIG3, that when expressed in keratinocytes causes increased transglutaminase activity and keratinocyte cell death. However, the mechanism of activation of transglutaminase by TIG3 is not known. We now extend our previous study and show that full-length TIG3 forms a complex with type I transglutaminase that is demonstrated by TIG3-transglutaminase co-precipitation. We also demonstrate that treating TIG3-expressing cells with monodansyl cadaverine, a competitive transglutaminase substrate, attenuates the TIG3-dependent response, suggesting that transglutaminase is an important mediator of TIG3 action. These findings suggest that TIG3 forms a complex with transglutaminase resulting in transglutaminase activation and that transglutaminase activity is required for the TIG3-dependent biological response.

Transglutaminase function in epidermis.

Surface epithelial cells, such as the epidermal keratinocyte, undergo a process of terminal cell differentiation that results in the construction of a multilayered epithelium. This epithelium functions to protect the organism from the environment. Transglutaminases, enzymes that catalyze the formation of isopeptide protein-protein cross-links, are key enzymes involved in the construction of this structure. This brief review will focus on the role of these enzymes in constructing the epidermal surface.

Human epidermal keratinocytes undergo (-)-epigallocatechin-3-gallate-dependent differentiation but not apoptosis.

Epigallocatechin-3-gallate (EGCG) is an important chemopreventive agent derived from green tea. We recently reported that EGCG treatment enhances keratinocyte differentiation as evidenced by increased human involucrin promoter activity [Balasubramanian,S., Efimova,T. and Eckert,R.L. (2002) J. Biol. Chem., 277, 1828-1836]. In the present paper, we extend these findings and show that EGCG also increases the expression of other differentiation markers-procaspase 14 and type I transglutaminase (TG1). Both TG1 mRNA and protein level, and activity are increased by treatment with EGCG. Increased TG1 activity is evidenced by a direct transglutaminase assay, and by the ability of EGCG to stimulate the covalent incorporation of fluorescein cadaverine substrate into crosslinked intracellular structures. In contrast, type II transglutaminase levels are not altered by EGCG treatment. We also assessed whether EGCG promotes keratinocyte apoptosis. We show that EGCG treatment does not promote the cleavage of procaspase-3, -8, -9 or poly(ADP-ribose) polymerase. Moreover, treatment with the pan-caspase inhibitor, Z-VAD-FMK, does not reverse the EGCG-associated reduction in cell viability. In addition, there is no increase in cells having sub-G(1)/S DNA content, and no evidence for the release of cytochrome c from the mitochondria. These findings confirm, using several endpoints, that EGCG treatment enhances normal keratinocyte differentiation but does not promote apoptosis.

A novel tumor suppressor protein promotes keratinocyte terminal differentiation via activation of type I transglutaminase.

Tazarotene-induced protein 3 (TIG3) is a recently discovered regulatory protein that is expressed in the suprabasal epidermis. In the present study, we show that TIG3 regulates keratinocyte viability and proliferation. TIG3-dependent reduction in keratinocyte viability is accompanied by a substantial increase in the number of sub-G1 cells, nuclear shrinkage, and increased formation of cornified envelope-like structures. TIG3 localizes to the membrane fraction, and TIG3-dependent differentiation is associated with increased type I transglutaminase activity. Microscopic localization and isopeptide cross-linking studies suggest that TIG3 and type I transglutaminase co-localize in membranes. Markers of apoptosis, including caspases and poly(ADP-ribose) polymerase, are not activated by TIG3, and caspase inhibitors do not stop the TIG3-dependent reduction in cell viability. Truncation of the carboxyl-terminal membrane-anchoring domain results in a complete loss of TIG3 activity. The morphology of the TIG3-positive cells and the effects on cornified envelope formation suggest that TIG3 is an activator of terminal keratinocyte differentiation. Our studies suggest that TIG3 facilitates the terminal stages in keratinocyte differentiation via activation of type I transglutaminase.

Keratinocyte survival, differentiation, and death: many roads lead to mitogen-activated protein kinase.

The epidermis is a dynamic and continually renewing surface that provides and maintains a life-sustaining interface with the environment. The epidermal keratinocyte, the major cell type of the epidermis, undergoes a complex and carefully choreographed program of differentiation. This process requires a balance between keratinocyte proliferation, differentiation, and apoptosis. This overview will concentrate on cascades that regulate the balance between keratinocyte cell proliferation and survival, and apoptosis and cell differentiation, with a particular emphasis on the role of the mitogen-activated protein kinase cascades. A summary of the literature suggests that extracellular regulated kinases function to promote keratinocyte proliferation and survival, whereas p38 mitogen-activated protein kinase functions to promote differentiation and apoptosis.