Interferon alpha-2 treatment reduces circulating neutrophil extracellular trap levels in myeloproliferative neoplasms.

Neutrophil extracellular traps (NETs) may play a pathogenic role in the thrombosis associated with myeloproliferative neoplasms (MPNs). We measured serum NET levels in 128 pretreatment samples from patients with MPNs and in 85 samples taken after 12 months of treatment with interferon alpha-2 (PEG-IFNα-2) formulations or hydroxyurea (HU). No differences in NET levels were observed across subdiagnoses or phenotypic driver mutations. In PV, a JAK2V617F+ allele burden ≥50% associated with increased NET levels (p = 0.006). Baseline NET levels correlated with neutrophil count (r = 0.29, p = 0.001), neutrophil-to-lymphocyte ratio (r = 0.26, p = 0.004) and JAK2V617F allele burden (r = 0.22, p = 0.03), particularly in patients with PV and with allele burden ≥50% (r = 0.50, p = 0.01, r = 0.56, p = 0.002 and r = 0.45, p = 0.03 respectively). In PV, after 12 months of treatment, NET levels decreased on average by 60% in patients with allele burden ≥50%, compared to only 36% in patients with an allele burden <50%. Overall, treatment with PEG-IFNα-2a or PEG-IFNα-2b reduced NETs levels in 77% and 73% of patients, respectively, versus only 53% of HU-treated patients (average decrease across treatments: 48%). Normalization of blood counts did not per se account for these reductions. In conclusion, baseline NET levels correlated with neutrophil count, NLR and JAK2V617F allele burden, and IFNα was more effective at reducing prothrombotic NET levels than HU.

Reproduction patterns among non-Hodgkin lymphoma survivors by subtype in Sweden, Denmark and Norway: A population-based matched cohort study.

Previous studies concerning reproductive patterns among non-Hodgkin lymphoma (NHL) survivors are scarce and those available have reported conflicting results. Treatment regimens vary considerably between aggressive and indolent NHL and studies of reproductive patterns by subtypes are warranted. In this matched cohort study, we identified all NHL patients aged 18-40 years and diagnosed between 2000 and 2018 from the Swedish and Danish lymphoma registers, and the clinical database at Oslo University Hospital (n = 2090). Population comparators were matched on sex, birth year and country (n = 19 427). Hazard ratios (HRs) were estimated using Cox regression. Males and females diagnosed with aggressive lymphoma subtypes had lower childbirth rates (HRfemale : 0.43, 95% CI: 0.31-0.59, HRmale : 0.61, 95% CI: 0.47-0.78) than comparators during the first 3 years after diagnosis. For indolent lymphomas, childbirth rates were not significantly different from comparators (HRfemale : 0.71, 95% CI: 0.48-1.04, HRmale : 0.94, 95% CI: 0.70-1.27) during the same period. Childbirth rates reached those of comparators for all subtypes after 3 years but the cumulative incidence of childbirths was decreased throughout the 10-year follow-up for aggressive NHL. Children of NHL patients were more likely to be born following assisted reproductive technology than those of comparators, except for male indolent lymphoma patients. In conclusion, fertility counselling is particularly important for patients with aggressive NHL.

Uterine, but not ovarian, female reproductive organ involvement at presentation by diffuse large B-cell lymphoma is associated with poor outcomes and a high frequency of secondary CNS involvement.

Involvement of the internal female reproductive organs by diffuse large B-cell lymphoma (DLBCL) is uncommon, and there are sparse data describing the outcomes of such cases. In total, 678 female patients with DLBCL staged with positron emission tomography/computed tomography and treated with rituximab-containing chemotherapy were identified from databases in Denmark, Great Britain, Australia, and Canada. Overall, 27/678 (4%) had internal reproductive organ involvement: uterus (n = 14), ovaries (n = 10) or both (n = 3). In multivariate analysis, women with uterine DLBCL experienced inferior progression-free survival and overall survival compared to those without reproductive organ involvement, whereas ovarian DLBCL was not predictive of outcome. Secondary central nervous system (CNS) involvement (SCNS) occurred in 7/17 (41%) women with uterine DLBCL (two patients with concomitant ovarian DLBCL) and 0/10 women with ovarian DLBCL without concomitant uterine involvement. In multivariate analysis adjusted for other risk factors for SCNS, uterine involvement by DLBCL remained strongly associated with SCNS (Hazard ratio 14·13, 95% confidence interval 5·09-39·25, P < 0·001). Because involvement of the uterus by DLBCL appears to be associated with a high risk of SCNS, those patients should be considered for CNS staging and prophylaxis. However, more studies are needed to determine whether the increased risk of secondary CNS involvement also applies to women with localized reproductive organ DLBCL.

Trends in hematological cancer in the elderly in Denmark, 1980-2012.

BACKGROUND: The number of hematological malignancies is expected to increase as the Danish population ages within the next few decades. Despite this, data on the course of hematological cancers among the oldest patients are sparse with many intervention studies focusing on younger age groups. The aim of this study is to present Danish incidence and mortality rates among older patients with non-Hodgkin lymphomas (NHL), multiple myeloma (MM), chronic lymphocytic leukemia (CLL), and acute myeloid leukemia (AML). MATERIAL AND METHODS: Nationwide population-based study presenting the incidence, prevalence and mortality rates of NHL, MM, and AML with a focus on the elderly population in Denmark during the last few decades. Data were drawn from the NORDCAN database. RESULTS: Incidence rates of NHL, MM, CLL and AML were 10-50 times higher among the population aged 70 years or more than among the younger population. An increasing incidence with stable or decreased mortality rates was seen mainly among elderly patients with NHL during the last few decades, leading to increased survival and a greater prevalence of patients with NHL. Increased relative survival and prevalence could also be seen among elderly patients with MM and CLL, while the trends of the incidence rates were inconclusive for these diseases. Survival among patients with AML improved most notably in those aged below 70 years leading to an increased prevalence of AML patients predominantly in this age group. CONCLUSION: Improvements in diagnostics and treatment have led to increased survival and therefore prevalence of elderly patients with NHL, MM, CLL and AML during the past decades.

Safety and efficacy of durvalumab with R-CHOP or R2-CHOP in untreated, high-risk DLBCL: a phase 2, open-label trial.

Patients with high-risk diffuse large B-cell lymphoma (DLBCL) have poor outcomes following first-line cyclophosphamide, doxorubicin, vincristine, prednisone, and rituximab (R-CHOP). Evidence shows chemotherapy and immune checkpoint blockade can increase antitumor efficacy. This study investigated durvalumab, a programmed death-ligand 1 inhibitor, combined with R-CHOP or lenalidomide + R-CHOP (R2-CHOP) in newly diagnosed high-risk DLBCL. Patients received durvalumab 1125 mg every 21 days for 2-8 cycles + R-CHOP (non-activated B-cell [ABC] subtype) or R2-CHOP (ABC), then durvalumab consolidation (1500 mg every 28 days). Of 46 patients, 43 received R-CHOP and three R2-CHOP. All patients had the high-risk disease; 14 (30.4%) and eight (17.4%) had double- or triple-hit DLBCL, respectively. Following induction, 20/37 (54.1%) patients receiving durvalumab + R-CHOP achieved complete response (CR), and seven (18.9%) partial response (PR); 25 (67.6% [95% CI 50.2-82.0]) continued to consolidation and were progression-free at 12 months. Among efficacy-evaluable patients with double- or triple-hit DLBCL (n = 12), five achieved CR and five PR. Adverse events were generally consistent with R-CHOP. Correlative analyses did not identify conclusive biomarkers of response. Durvalumab + R-CHOP is feasible in DLBCL with no new safety signals, but the combination provided no greater benefit than R-CHOP.

Perspective: sensitive detection of residual lymphoproliferative disease by NGS and clonal rearrangements-how low can you go?

Malignant lymphoproliferative disorders collectively constitute a large fraction of the hematological cancers, ranging from indolent to highly aggressive neoplasms. Being a diagnostically important hallmark, clonal gene rearrangements of the immunoglobulins enable the detection of residual disease in the clinical course of patients down to a minute fraction of malignant cells. The introduction of next-generation sequencing (NGS) has provided unprecedented assay specificity, with a sensitivity matching that of polymerase chain reaction-based measurable residual disease (MRD) detection down to the 10-6 level. Although reaching 10-6 to 10-7 is theoretically feasible, employing a sufficient amount of DNA and sequencing coverage is placed in the perspective of the practical challenges when relying on clinical samples in contrast to controlled serial dilutions. As we discuss, the randomness of subsampling must be taken into account to accommodate the sensitivity threshold-in terms of both the required number of cells and sequencing coverage. As a substantial part of the reviewed studies do not state the depth of coverage or even amount of DNA in some cases, we call for increased transparency to enable critical assessment of the MRD assays for clinical implementation and feasibility.

Molecular mechanisms associated with leukemic transformation of MPL-mutant myeloproliferative neoplasms.

Somatic activating mutations in MPL, the thrombopoietin receptor, occur in the myeloproliferative neoplasms, although virtually nothing is known about their role in evolution to acute myeloid leukemia. In this study, the MPL T487A mutation, identified in de novo acute myeloid leukemia, was not detected in 172 patients with a myeloproliferative neoplasm. In patients with a prior MPL W515L-mutant myeloproliferative neoplasm, leukemic transformation was accompanied by MPL-mutant leukemic blasts, was seen in the absence of prior cytoreductive therapy and often involved loss of wild-type MPL by mitotic recombination. Moreover, clonal analysis of progenitor colonies at the time of leukemic transformation revealed the presence of multiple genetically distinct but phylogenetically-related clones bearing different TP53 mutations, implying a mutator-phenotype and indicating that leukemic transformation may be preceded by the parallel expansion of diverse hematopoietic clones.

Data-driven analysis of JAK2V617F kinetics during interferon-alpha2 treatment of patients with polycythemia vera and related neoplasms.

Treatment with PEGylated interferon-alpha2 (IFN) of patients with essential thrombocythemia and polycythemia vera induces major molecular remissions with a reduction in the JAK2V617F allele burden to undetectable levels in a subset of patients. A favorable response to IFN has been argued to depend upon the tumor burden, implying that institution of treatment with IFN should be as early as possible after the diagnosis. However, evidence for this statement is not available. We present a thorough analysis of unique serial JAK2V617F measurements in 66 IFN-treated patients and in 6 untreated patients. Without IFN treatment, the JAK2V617F allele burden increased exponentially with a period of doubling of 1.4 year. During monotherapy with IFN, the JAK2V617F allele burden decreased mono- or bi-exponentially for 33 responders of which 28 patients satisfied both descriptions. Bi-exponential description improved the fits in 19 cases being associated with late JAK2V617F responses. The decay of the JAK2V617F allele burden during IFN treatment was estimated to have half-lives of 1.6 year for the monoexponential response and 1.0 year in the long term for the bi-exponential response. In conclusion, through data-driven analysis of the JAK2V617F allele burden, we provide novel information regarding the JAK2V617F kinetics during IFN-treatment, arguing for early intervention.

Clinical impact of clonal hematopoiesis in patients with lymphoma undergoing ASCT: a national population-based cohort study.

Clonal hematopoiesis of indeterminate potential (CHIP) is suspected of being a risk factor for patients with cancer. This study aimed to assess the clinical consequences of CHIP in patients with lymphoma intended for high-dose chemotherapy and autologous stem-cell transplantation (ASCT) in a population-based setting. We identified 892 lymphoma patients who had undergone stem cell harvest at all transplant centers in Denmark. A total of 565 patients had an available harvest sample, which was analysed for CHIP by next-generation sequencing, and the median follow-up was 9.1 years. Of the patients who were intended for immediate ASCT, 25.5% (112/440) carried at least one CHIP mutation. In contrast to previous single-center studies CHIP was not associated with inferior overall survival (OS) in multivariate analyses. However, patients with mutations in genes of the DNA repair pathway (PPM1D, TP53, RAD21, BRCC3) had a significant inferior OS (HR after 1 year of follow-up 2.79, 95% confidence interval 1.71-4.56; p < 0.0001), which also was evident in multivariate analysis (p = 0.00067). These patients had also increased rates of therapy-related leukemia and admission to intensive care. Furthermore, in patients who did not undergo immediate ASCT, a significant inferior OS of individuals with DNA repair mutations was also identified (p = 0.003).

Risk of death, relapse or progression, and loss of life expectancy at different progression-free survival milestones in primary central nervous system lymphoma.

In this study, we analyzed the evolution of the prognosis of primary central nervous system lymphoma (PCNSL) patients as they reach selected progression-free survival (PFS) milestones after high-dose methotrexate (HD-MTX)-based therapy. In total, 258 and 146 patients were included from Denmark and British Columbia, respectively. All patients were diagnosed during 2000-2017. The 5-year PFS was 27% (95% CI 23; 32); however, for patients reaching 5 years of PFS, this increased to 71% (95% CI 57; 86). Within the first 5 years after diagnosis, patients lost 2.0 years (95% CI 1.8; 2.2) when compared to a similar background population. This reduced to 0.5 years (95% CI 0.2; 0.9) for patients reaching 5 years of PFS. Treatment with rituximab was associated with improved outcomes. The prognosis of patients with PCNSL treated with HD-MTX-based regimens in this cohort is poor, although it improves as patients survive without progression/relapse. However, survival does not conclusively normalize to that of a similar background population.

Pretreatment Hemoglobin Adds Prognostic Information To The NCCN-IPI In Patients With Diffuse Large B-Cell Lymphoma Treated With Anthracycline-Containing Chemotherapy.

BACKGROUND: Hemoglobin (Hgb) concentration at diagnosis is associated with outcome in cancer. In a recently reported simplified 3-factor prognostic score in Hodgkin lymphoma, Hgb, along with age and clinical stage, outperformed the classical International Prognostic Score with seven parameters. METHODS: In the present study, we investigated if pretherapeutic Hgb concentration added prognostic information to the NCCN-IPI in diffuse large B-cell lymphoma. We included patients from the Danish Lymphoma Registry (LYFO; N = 3499) and from the Molecular Epidemiology Resource (MER; N = 1225), Mayo Clinic and University of Iowa. Four sex-specific Hgb groups were defined: below transfusion threshold, from transfusion threshold to below lower limit of normal, from lower limit of normal to the population mean, and above the mean. We used multivariable Cox regression to estimate the hazard rate ratios (HR) and 95% CIs for overall survival (OS) and event-free survival (EFS), adjusting for sex, NCCN-IPI, comorbidity, and rituximab treatment. RESULTS: Approximately half of the patients had Hgb levels below the lower limit of normal. Compared to patients with Hgb levels above the mean, an inferior OS was directly correlated with lower pretreatment Hgb within the predefined groups (HR=1.23, HR=1.51, and HR=2.05, respectively). These findings were validated in the MER. CONCLUSION: Based on multivariable analysis, lower pretreatment Hgb, even within the normal range but below the mean, added prognostic information to established indices such as the NCCN-IPI and the Charlson comorbidity index.

Chronic lymphocytic leukemia patients with heterogeneously or fully methylated LPL promotor display longer time to treatment.

AIM: We investigated whether DNA methylation regulates expression of LPL and PI3K complex genes in chronic lymphocytic leukemia (CLL) and evaluated the prognostic significance of LPL promoter methylation in CLL patients. Patients & methods: Methylation of LPL promoter was assessed in 112 patients using methylation-sensitive high-resolution melting (MS-HRM). RESULTS: Patients with a fully or heterogeneously methylated LPL promoter had significantly longer median time to treatment (p < 0.001) and 75% lower (hazard ratio: 0.25; 95% CI: 0.15-0.42; p < 0.001) risk of requirement for treatment as opposed to patients with nonmethylated promoter. Multivariate modeling confirmed independent prognostic value of these findings. CONCLUSION: Chronic lymphocytic leukemia patients with a fully or heterogeneously methylated LPL gene promoter display indolent disease course and acquisition of heterogeneous methylation of LPL promoter is insufficient to induce gene expression.

Treatment strategies, outcomes and prognostic factors in 291 patients with secondary CNS involvement by diffuse large B-cell lymphoma.

PURPOSE: Secondary CNS involvement (SCNS) is a profoundly adverse complication of diffuse large B-cell lymphoma. Evidence from older series indicated a median overall survival (OS) < 6 months; however, data from the immunochemotherapy era are limited. METHODS: Patients diagnosed with SCNS during or after first-line immunochemotherapy were identified from databases and/or regional/national registries from three continents. Clinical information was retrospectively collected from medical records. RESULTS: In total, 291 patients with SCNS were included. SCNS occurred as part of first relapse in 254 (87%) patients and 113 (39%) had concurrent systemic relapse. With a median post-SCNS follow-up of 48 months, the median post-SCNS OS was 3.9 months and 2-year OS rate was 20% (95% CI: 15-25). In multivariable analysis of 173 patients treated with curative/intensive therapy (such as high-dose methotrexate [HDMTX] or platinum-containing regimens), age ≤60 years, performance status 0-1, absence of combined leptomeningeal and parenchymal involvement, and SCNS occurring after completion of first-line therapy were associated with superior outcomes. Patients ≤60 years with performance status 0-1 and treated with HDMTX-based regimens for isolated parenchymal SCNS had a 2-year OS of 62% (95% CI: 36-80). In patients with isolated SCNS, the addition of rituximab to HDMTX-based regimens was associated with improved OS. Amongst patients with isolated SCNS in CR following intensive treatment, high-dose chemotherapy and autologous stem cell transplantation did not improve OS (P = 0.9). CONCLUSIONS: In this large international cohort of patients treated with first-line immunochemotherapy, outcomes following SCNS remain poor. However, a moderate proportion of patients with isolated SCNS who received intensive therapies achieved durable remissions.

The number of extranodal sites assessed by PET/CT scan is a powerful predictor of CNS relapse for patients with diffuse large B-cell lymphoma: An international multicenter study of 1532 patients treated with chemoimmunotherapy.

PURPOSE: Development of secondary central nervous system involvement (SCNS) in patients with diffuse large B-cell lymphoma is associated with poor outcomes. The CNS International Prognostic Index (CNS-IPI) has been proposed for identifying patients at greatest risk, but the optimal model is unknown. METHODS: We retrospectively analysed patients with diffuse large B-cell lymphoma diagnosed between 2001 and 2013, staged with PET/CT and treated with R-CHOP(-like) regimens. Baseline clinicopathologic characteristics, treatments, and outcome data were collected from clinical databases and medical files. We evaluated the association between candidate prognostic factors and modelled different risk models for predicting SCNS. RESULTS: Of 1532 patients, 62 (4%) subsequently developed SCNS. By multivariate analysis, disease stage III/IV, elevated serum LDH, kidney/adrenal and uterine/testicular involvement were independently associated with SCNS. There was a strong correlation between absolute number of extranodal sites and risk of SCNS; the 144 patients (9%) with >2 extranodal sites had a 3-year cumulative incidence of SCNS of 15.2% (95% confidence interval [CI] 9.2-21.2%) compared with 2.6% (95% CI 1.7-3.5) among those with ≤2 sites (P < 0.001). The 3-year cumulative risks of SCNS for CNS-IPI defined risk groups were 11.2%, 3.1% and 0.4% for high-, intermediate- and low-risk patients, respectively. All risk models analysed had high negative predictive values, but only modest positive predictive values. CONCLUSIONS: Patients with >2 extranodal sites or high-risk disease according to the CNS-IPI should be considered for baseline CNS staging. Clinical risk prediction models suffer from limited positive predictive ability, highlighting the need for more sensitive biomarkers to identify patients at highest risk of this devastating complication.

Differential Dynamics of CALR Mutant Allele Burden in Myeloproliferative Neoplasms during Interferon Alfa Treatment.

Discovery of somatic mutations in the calreticulin gene (CALR) has identified a subgroup of Philadelphia-negative chronic myeloproliferative neoplasms (MPN) with separate haematological characteristics and prognosis. CALR mutations serve as novel markers both of diagnostic value and as targets for monitoring molecular responses during therapy. Interferon-α (IFN) selectively targets the malignant clone in a subset of MPN patients and can induce both haematological and molecular remissions in CALR mutated essential thrombocythemia (ET) patients. We investigated the response to IFN in a cohort of 21 CALR mutated MPN patients including ET, prefibrotic primary myelofibrosis (pre-PMF), and primary myelofibrosis (PMF) with a median follow-up of 31 months. For evaluation of a molecular response, we developed highly sensitive quantitative PCR (qPCR) assays for monitoring the mutant allele burden of the two most prevalent CALR mutations (type 1 and type 2). Thirteen patients (62%) experienced a decrease in the mutant allele burden with a median decline of 29% from baseline. However, only four patients, including patients with ET, pre-PMF, and PMF diagnosis, achieved molecular responder (MR) status with >50% reduction in mutant allele burden according to European LeukemiaNet (ELN) guidelines. MR patients displayed significant differences in the dynamics of the CALR mutant load with regard to time to response and dynamics in mutant allele burden after discontinuation of IFN treatment. Furthermore, we highlight the prognostic value of the CALR mutant allele burden by showing a close association with leucocyte- and platelet counts, hemoglobin concentration, in addition to plasma lactate dehydrogenase (LDH) irrespective of molecular response and treatment status.

RpoD promoters in Campylobacter jejuni exhibit a strong periodic signal instead of a -35 box.

We have used a hidden Markov model (HMM) to identify the consensus sequence of the RpoD promoters in the genome of Campylobacter jejuni. The identified promoter consensus sequence is unusual compared to other bacteria, in that the region upstream of the TATA-box does not contain a conserved -35 region, but shows a very strong periodic variation in the AT-content and semi-conserved T-stretches, with a period of 10-11 nucleotides. The TATA-box is in some, but not all cases, preceded by a TGx, similar to an extended -10 promoter. We predicted a total of 764 presumed RpoD promoters in the C.jejuni genome, of which 654 were located upstream of annotated genes. A similar promoter was identified in Helicobacter pylori, a close phylogenetic relative of Campylobacter, but not in Escherichia coli, Vibrio cholerae, or six other Proteobacterial genomes, or in Staphylococcus aureus. We used upstream regions of high confidence genes as training data (n=529, for the C.jejuni genome). We found it necessary to limit the training set to genes that are preceded by an intergenic region of >100bp or by a gene oriented in the opposite direction to be able to identify a conserved sequence motif, and ended up with a training set of 175 genes. This leads to the conclusion that the remaining genes (354) are more rarely preceded by a (RpoD) promoter, and consequently that operon structure may be more widespread in C.jejuni than has been assumed by others. Structural predictions of the regions upstream of the TATA-box indicates a region of highly curved DNA, and we assume that this facilitates the wrapping of the DNA around the RNA polymerase holoenzyme, and offsets the absence of a conserved -35 binding motif.

The nature of corticospinal paths driving human motoneurones during voluntary contractions.

The properties of the human motor cortex can be studied non-invasively using transcranial magnetic stimulation (TMS). Stimulation at high intensity excites corticospinal cells with fast conducting axons that make direct connections to motoneurones of human upper limb muscles, while low-intensity stimulation can suppress ongoing EMG. To assess whether these cells are used in normal voluntary contractions, we used TMS at very low intensities to suppress the firing of single motor units in biceps brachii (n = 14) and first dorsal interosseous (FDI, n = 6). Their discharge was recorded with intramuscular electrodes and cortical stimulation was delivered at multiple intensities at appropriate times during sustained voluntary firing at approximately 10 Hz. For biceps, high-intensity stimulation produced facilitation at 17.1 +/- 2.1 ms (lasting 2.4 +/- 0.9 ms), while low-intensity stimulation (below motor threshold) produced suppression (without facilitation) at 20.2 +/- 2.1 ms (lasting 7.6 +/- 2.2 ms). For FDI, high-intensity stimulation produced facilitation at 23.3 +/- 1.2 ms (lasting 1.8 +/- 0.4 ms), with suppression produced by low-intensity stimulation at 25.2 +/- 2.6 ms (lasting 7.5 +/- 2.6 ms). The difference between the onsets of facilitation and suppression was short: 3.1 +/- 1.2 ms for biceps and 2.0 +/- 1.5 ms for FDI. This latency difference is much less than that previously reported using surface EMG recordings ( approximately 10 ms). These data suggest that low-intensity cortical stimulation inhibits ongoing activity in fast-conducting corticospinal axons through an oligosynaptic (possibly disynaptic) path, and that this activity is normally contributing to drive the motoneurones during voluntary contractions.

Sigma A recognition sites in the Bacillus subtilis genome.

A hidden Markov model of sigma(A) RNA polymerase cofactor recognition sites in Bacillus subtilis, containing either the common or the extended -10 motifs, has been constructed based on experimentally verified sigma(A) recognition sites. This work suggests that more information exists at the initiation site of transcription in both types of promoters than previously thought. When tested on the entire B. subtilis genome, the model predicts that approximately half of the sigma(A) recognition sites are of the extended type. Some of the response-regulator aspartate phosphatases were among the predictions of promoters containing extended sites. The expression of rapA and rapB was confirmed by site-directed mutagenesis to depend on the extended -10 region.