Application of IPSET-thrombosis in 1366 Patients Prospectively Followed From the Spanish Registry of Essential Thrombocythemia

The International Prognostic Score of thrombosis in Essential Thrombocythemia (IPSET-thrombosis) and its revised version have been proposed to guide thrombosis prevention strategies. We evaluated both classifications to prognosticate thrombosis in 1366 contemporary essential thrombocythemia (ET) patients prospectively followed from the Spanish Registry of ET. The cumulative incidence of thrombosis at 10 years, taking death as a competing risk, was 11.4%. The risk of thrombosis was significantly higher in the high-risk IPSET-thrombosis and high-risk revised IPSET-thrombosis, but no differences were observed among the lower risk categories. Patients allocated in high-risk IPSET-thrombosis (subdistribution hazard ratios [SHR], 3.7 [95% confidence interval, CI, 1.6-8.7]) and high-risk revised IPSET-thrombosis (SHR, 3.2 [95% CI, 1.4-7.45]) showed an increased risk of arterial thrombosis, whereas both scoring systems failed to predict venous thrombosis. The incidence rate of thrombosis in intermediate risk revised IPSET-thrombosis (aged >60 years, JAK2-negative, and no history of thrombosis) was very low regardless of the treatment administered (0.9% and 0% per year with and without cytoreduction, respectively). Dynamic application of the revised IPSET-thrombosis showed a low rate of thrombosis when patients without history of prior thrombosis switched to a higher risk category after reaching 60 years of age. In conclusion, IPSET-thrombosis scores are useful for identifying patients at high risk of arterial thrombosis, whereas they fail to predict venous thrombosis. Controlled studies are needed to determine the appropriate treatment of ET patients assigned to the non-high-risk categories.

Real-world analysis of main clinical outcomes in patients with polycythemia vera treated with ruxolitinib or best available therapy after developing resistance/intolerance to hydroxyurea

Background

Ruxolitinib is approved for patients with polycythemia vera (PV) who are resistant/intolerant to hydroxyurea, but its impact on preventing thrombosis or disease‐progression is unknown.

Methods

A retrospective, real‐world analysis was performed on the outcomes of 377 patients with resistance/intolerance to hydroxyurea from the Spanish Registry of Polycythemia Vera according to subsequent treatment with ruxolitinib (n = 105) or the best available therapy (BAT; n = 272). Survival probabilities and rates of thrombosis, hemorrhage, acute myeloid leukemia, myelofibrosis, and second primary cancers were calculated according to treatment. To minimize biases in treatment allocation, all results were adjusted by a propensity score for receiving ruxolitinib or BAT.

Results

Patients receiving ruxolitinib had a significantly lower rate of arterial thrombosis than those on BAT (0.4% vs 2.3% per year; P = .03), and this persisted as a trend after adjustment for the propensity to have received the drug (incidence rate ratio, 0.18; 95% confidence interval, 0.02‐1.3; P = .09). There were no significant differences in the rates of venous thrombosis (0.8% and 1.1% for ruxolitinib and BAT, respectively; P = .7) and major bleeding (0.8% and 0.9%, respectively; P = .9). Ruxolitinib exposure was not associated with a higher rate of second primary cancers, including all types of neoplasia, noncutaneous cancers, and nonmelanoma skin cancers. After a median follow‐up of 3.5 years, there were no differences in survival or progression to acute leukemia or myelofibrosis between the 2 groups.

Conclusions

The results suggest that ruxolitinib treatment for PV patients with resistance/intolerance to hydroxyurea may reduce the incidence of arterial thrombosis.

Lay Summary

Ruxolitinib is better than other available therapies in achieving hematocrit control and symptom relief in patients with polycythemia vera who are resistant/intolerant to hydroxyurea, but we still do not know whether ruxolitinib provides an additional benefit in preventing thrombosis or disease progression.

We retrospectively studied the outcomes of 377 patients with resistance/intolerance to hydroxyurea from the Spanish Registry of Polycythemia Vera according to whether they subsequently received ruxolitinib (n = 105) or the best available therapy (n = 272).

Our findings suggest that ruxolitinib could reduce the incidence of arterial thrombosis, but a disease‐modifying effect could not be demonstrated for ruxolitinib in this patient population.

Ruxolitinib may reduce the incidence of arterial thrombosis in patients with polycythemia vera resistant/intolerant to hydroxyurea.

Low-risk polycythemia vera treated with phlebotomies: clinical characteristics, hematologic control and complications in 453 patients from the Spanish Registry of Polycythemia Vera

Hematological control, incidence of complications, and need for cytoreduction were studied in 453 patients with low-risk polycythemia vera (PV) treated with phlebotomies alone. Median hematocrit value decreased from 54% at diagnosis to 45% at 12 months, and adequate hematocrit control over time (< 45%) was observed in 36%, 44%, and 32% of the patients at 6, 12, and 24 months, respectively. More than 5 phlebotomies per year in the maintenance phase were required in 19% of patients. Worsening thrombocytosis, age > 60 years, and microvascular symptoms constituted the main indications for starting cytoreduction. Median duration without initiating cytoreduction was significantly longer in patients younger than 50 years (< 0.0001). The incidence rate of thrombosis under phlebotomies alone was 0.8% per year and the estimated probability of thrombosis at 10 years was 8.5%. The probability of arterial thrombosis was significantly higher in patients with arterial hypertension whereas there was a trend to higher risk of venous thrombosis in cases with high JAK2V617F allele burden. Rates of major bleeding and second primary neoplasm were low. With a median follow-up of 9 years, survival probability at 10 years was 97%, whereas the probability of myelofibrosis at 10 and 20 years was 7% and 20%, respectively. Progression to acute myeloid leukemia was documented in 3 cases (1%). Current management of low-risk PV patients is associated with low rate of thrombosis and long survival. New treatment strategies are needed for improving hematological control and, in the long term, reducing progression to myelofibrosis.

Pomalidomide, Cyclophosphamide, and Dexamethasone for the Treatment of Relapsed/Refractory Multiple Myeloma: Real-World Analysis of the Pethema-GEM Experience

INTRODUCTION

Treatment of relapsed/refractory multiple myeloma (RRMM) is highly challenging, especially for patients with disease refractory to initial therapy, and in particular for disease developing refractoriness to lenalidomide. Indeed, with currently approved treatments, median progression-free survival (PFS) in the lenalidomide-refractory setting is less than 10 months, reflecting the difficulty in treating this patient population. Pomalidomide is a second-generation immunomodulatory drug that has shown activity in lenalidomide-refractory disease in the setting of different combinations.

PATIENTS AND METHODS

A real-world study was conducted by the Spanish Myeloma group in a cohort of patients with RRMM treated with pomalidomide, cyclophosphamide, and dexamethasone (PomCiDex). One hundred patients were treated with a median of 3 prior lines of therapy.

RESULTS

Overall response rate was 39%, with a clinical benefit rate of 93%. Median PFS was 7.6 months; median overall survival (OS) was 12.6 months. Median PFS and OS survival were consistent across the different subgroups analyzed. Prolonged PFS and OS were found in patients with responsive disease.

CONCLUSION

Our results compared favorably with those obtained with different pomalidomide-based combinations in a similar patient population. PomCiDex remains a manageable, cost-effective, and all-oral triplet combination for RRMM patients.

6q deletion in Waldenström macroglobulinaemia negatively affects time to transformation and survival

Deletion of the long arm of chromosome 6 (del6q) is the most frequent cytogenetic abnormality in Waldenström macroglobulinaemia (WM), occurring in approximately 50% of patients. Its effect on patient outcome has not been completely established. We used fluorescence in situ hybridisation to analyse the prevalence of del6q in selected CD19+ bone marrow cells of 225 patients with newly diagnosed immunoglobulin M (IgM) monoclonal gammopathies. Del6q was identified in one of 27 (4%) cases of IgM-monoclonal gammopathy of undetermined significance, nine of 105 (9%) of asymptomatic WM (aWM), and 28/93 (30%) of symptomatic WM (sWM), and was associated with adverse prognostic features and higher International Prognostic Scoring System for WM (IPSSWM) score. Asymptomatic patients with del6q ultimately required therapy more often and had a shorter time to transformation (TT) to symptomatic disease (median TT, 30 months vs. 199 months, respectively, P < 0·001). When treatment was required, 6q-deleted patients had shorter progression-free survival (median 20 vs. 47 months, P < 0·001). The presence of del6q translated into shorter overall survival (OS), irrespective of the initial diagnosis, with a median OS of 90 compared with 131 months in non-del6q patients (P = 0·01). In summary, our study shows that del6q in IgM gammopathy is associated with symptomatic disease, need for treatment and poorer clinical outcomes.

Cytoreductive treatment in patients with CALR-mutated essential thrombocythaemia: a study comparing indications and efficacy among genotypes from the Spanish Registry of Essential Thrombocythaemia

The present study assessed the criteria for initiating cytoreduction and response to conventional therapies in 1446 patients with essential thrombocythemia (ET), 267 (17%) of which were CALR-mutated. In low risk patients, time from diagnosis to cytoreduction was shorter in CALR-positive than in the other genotypes (2·8, 3·2, 7·4 and 12·5 years for CALR, MPL, JAK2V617F and TN, respectively, P < 0·0001). A total of 1104 (76%) patients received cytoreductive treatment with hydroxycarbamide (HC) (n = 977), anagrelide (n = 113), or others (n = 14). The estimated cumulative rates of complete haematological response (CR) at 12 months were 40 % and 67% in CALR and JAK2V617F genotypes, respectively. Median time to CR was 192 days for JAK2V617F, 343 for TN, 433 for MPL, and 705 for CALR genotypes (P < 0·0001). Duration of CR was shorter in CALR-mutated ET than in the remaining patients (P = 0·003). In CALR-positive patients, HC and anagrelide had similar efficacy in terms of response rates and duration. CALR-mutated patients developed resistance/intolerance to HC more frequently (5%, 23%, 27% and 15% for JAK2V617F, CALR, MPL and TN, respectively; P < 0·0001). In conclusion, conventional cytoreductive agents are less effective in CALR-mutated ET, highlighting the need for new treatment modalities and redefinition of haematologic targets for patients with this genotype.

Genetic Dissection of the Signaling Cascade that Controls Activation of the Shigella Type III Secretion System from the Needle Tip

Many Gram-negative bacterial pathogens use type III secretion systems (T3SSs) for virulence. The Shigella T3SS consists of a hollow needle, made of MxiH and protruding from the bacterial surface, anchored in both bacterial membranes by multimeric protein rings. Atop the needle lies the tip complex (TC), formed by IpaD and IpaB. Upon physical contact with eukaryotic host cells, T3S is initiated leading to formation of a pore in the eukaryotic cell membrane, which is made of IpaB and IpaC. Through the needle and pore channels, further bacterial proteins are translocated inside the host cell to meditate its invasion. IpaD and the needle are implicated in transduction of the host cell-sensing signal to the T3S apparatus. Furthermore, the sensing-competent TC seems formed of 4 IpaDs topped by 1 IpaB. However, nothing further is known about the activation process. To investigate IpaB’s role during T3SS activation, we isolated secretion-deregulated IpaB mutants using random mutagenesis and a genetic screen. We found ipaB point mutations in leading to defects in secretion activation, which sometimes diminished pore insertion and host cell invasion. We also demonstrated IpaB communicates intramolecularly and intermolecularly with IpaD and MxiH within the TC because mutations affecting these interactions impair signal transduction.

Transcriptional activation of a maize calcium-dependent protein kinase gene in response to fungal elicitors and infection

Plants respond to pathogen infection with the activation of the expression of pathogenesis-related genes, a response that involves Ca2+-regulated protein phosphorylation processes. We report here the isolation of a full-length complementary DNA encoding a calcium-dependent protein kinase (CPK) gene from maize. CPK genes occur in maize as members of a multigene family, but only one specific CPK gene, the ZmCPK10 gene here described, is transcriptionally activated in response to both fungal infection and treatment with fungal elicitors. Activation of the ZmCPK10 gene is extremely rapid. ZmCPK10 transcripts could be detected 5 min after elicitation and reached maximum levels at 30 min after treatment. Afterwards, there was a decline in the level of ZmCPK10 transcripts followed by a basal level of accumulation which is maintained over the time period of elicitor treatment. The activation of this kinase is accompanied by an increase in the level of PRms mRNA, the PRms being a pathogenesis-related protein from maize whose expression is induced in maize tissues in response to fungal infection and treatment with fungal elicitors. In situ mRNA hybridization analysis revealed a remarkable cell-type specific pattern of expression of ZmCPK10 during growth and development of the elicitor-treated or fungus-infected seedling. Moreover, the ZmCPK10 gene is expressed only in those specific cell types in which the PRms gene is also expressed. The involvement of ZmCPK10 in the elicitor-induced signal transduction pathway leading to the activation of PRms gene expression is discussed.

Pigment signatures associated with an anoxic coastal zone: Bahia Concepcion, Gulf of California

Bahia Concepcion is a coastal lagoon that has bottom anoxic conditions and high pigment concentrations during the summer. The phytoplankton responsible for this pigment increase is enigmatic, therefore we sampled the lagoon to analyze the pigment with a C8-HPLC system to look for signatures of phytoplankton groups. Analysis reveals a low pigment concentration in the mixed layer with a higher concentration of zeaxanthin and increasing values of chlorophyll a, peridinin, and fucoxanthin below, which peaked at the depth where oxygen dramatically decreases and H(2)S increases. Below this depth, a high pigmentation was recorded and the most important signatures were six chlorophyll-like pigments that eluted between the fucoxanthin and the chlorophyll a, and one carotenoid that eluted just after the chlorophyll a. Spectral characteristics of these last pigments are very similar to pigments present in the Chlorobiales group. These results suggest that cyanobacteria, diatoms, and dinoflagellates are responsible for the chlorophyll a increases, though in highly pigmented samples, anoxygenic phototrophic bacteria are probably the main contributors to the increase in pigments.

Cytology of Infection of Maize Seedlings by Fusarium moniliforme and Immunolocalization of the Pathogenesis-Related PRms Protein

ABSTRACT We have investigated the histology of infection of maize seedlings by Fusarium moniliforme in association with a biochemical host defense response, the accumulation of the PRms (pathogenesis-related maize seed) protein. Light microscopy of trypan blue-stained sections and scanning electron microscopy revealed direct penetration by F. moniliforme hyphae through the epidermal cells of the seedling and colonization of the host tissue by inter- and intracellular modes of growth. Pathogen ingress into the infected tissue was associated with the induction of defense-related ultrastructural modifications, as exemplified by the formation of appositions on the outer host cell wall surface, the occlusion of intercellular spaces, and the formation of papillae. Cellular and subcellular immunolocalization studies revealed that PRms accumulated at very high levels in those cells types that represent the first barrier for fungal penetration such as the aleurone layer of germinating seeds and the scutellar epithelial cells of isolated germinating embryos. A highly localized accumulation of PRms within papillae of the inner scutellar parenchyma cells also occurred, suggesting that signaling mechanisms that lead to the accumulation of PRms in papillae of cell types that are distant from the invading pathogen must operate in the infected maize tissues. Our study also revealed the presence of a large number of fungal cells with an abnormal shape that showed PRms-specific labeling. PRms was found to accumulate in clusters over the fungal cell wall. Taken together, the occurrence of PRms in cell types that first establish contact with the pathogen, as well as in papillae, and in association with fungal cell walls suggests that PRms may have a function in the plant defense response.

Measurement of intracellular pH of maize seeds (Zea mays) during germination by 31P nuclear magnetic resonance spectroscopy

The 31P NMR spectra of germinating maize seeds showed a single broad resonance that shifted its position as germination proceeded (studied between 0 and 10 days). The resonance was shown to originate from the phosphate groups of phytine (Mg2+, Ca2+ and K+ salt of myoinositol hexakisphosphate) in a subcellular compartment of the embryo scutellar cells. A series of calibration curves for the chemical shift dependence of the phytate resonance in the presence of Mg2+ and Ca2+ were constructed. These calibration curves allowed us to determine that an acidification of the phytate containing compartment in the seed embryo takes place, reaching a minimum at about pH 4 after three days of germination. This acidification could be important in allowing phytate solubilization for export to growing parts of the maize seedling.

The maize pathogenesis-related PRms protein localizes to plasmodesmata in maize radicles

Pathogenesis-related (PR) proteins are plant proteins induced in response to infection by pathogens. In this study, an antibody raised against the maize PRms protein was used to localize the protein in fungal-infected maize radicles. The PRms protein was found to be localized at the contact areas between parenchyma cells of the differentiating protoxylem elements. By using immunoelectron microscopy, we found that these immunoreactive regions correspond to plasmodesmal regions. This was also true for the parenchyma cells filling the central pith of the vascular cylinder, although PRms mRNA accumulation was not detected in these cells. These findings suggest that for one cell type, the parenchyma cells of the central pith, the protein is imported rather than synthesized. The localization of the PRms protein indicates the possible existence of mechanisms for sorting of plant proteins to plasmodesmata and suggests that this protein may have a specialized function in the plant defense response. These findings are discussed with respect to the structure and function of plasmodesmata in cell-to-cell communication processes in higher plants.