Real-world predictors of survival in patients with extensive-stage small-cell lung cancer in Manitoba, Canada: a retrospective cohort study.

Background: Extensive-stage small-cell lung cancer (ES-SCLC) is an incurable cancer with poor prognosis in which characteristics predictive of long-term survival are debated. The utility of agents such as immune checkpoint inhibitors highlights the importance of identifying key characteristics and treatment strategies that contribute to long-term survival and could help guide therapeutic decisions. Objective: This real-world analysis examines the characteristics, treatment patterns, and clinical outcomes of patients receiving chemotherapy without immunotherapy for ES-SCLC in Manitoba, Canada. Methods: A retrospective cohort study assessed patient characteristics, treatment, and survival duration (short: <6 months; medium: 6-24 months; long: >24 months) using the Manitoba Cancer Registry and CancerCare Manitoba records. Eligible patients were aged >18 years with cytologically confirmed ES-SCLC diagnosed between January 1, 2004, and December 31, 2018, and received cytotoxic chemotherapy (CT). The one-, two-, and five-year probabilities of overall survival (OS) were assessed relative to patient, disease, and treatment characteristics using Kaplan-Meier methods and Cox proportional hazards models. Results: This analysis included 537 patients. Cisplatin was used in 56.1% of patients, 45.6% received thoracic radiotherapy (RT), and few received prophylactic cranial irradiation (PCI). In the overall cohort, one-, two- and five-year OS rates were 26%, 8%, and 3%, respectively. For patients with Eastern Cooperative Oncology Group Performance Status (ECOG PS) 0, OS rates at one, two, and five years were 43%, 17%, and 10%, respectively, vs. 27%, 8%, and 2% for those with ECOG PS 1-2, and 16%, 3%, and 3% for those with ECOG PS 3-4. In long-term survivors, ECOG PS scores were lower and abnormal laboratory test results were less frequent. Overall, 74.4% of long-term survivors received thoracic RT and 53.5% received PCI. Known poor prognostic factors - including brain/liver metastases, high lactate dehydrogenase (LDH), abnormal sodium, and low hemoglobin levels - were less common but still seen in long-term survivors. Conclusion: Although rare, patients with ES-SCLC may experience long-term survival with CT ± thoracic RT ± PCI. Factors predicting long-term survival include traditional prognostic factors such as ECOG PS, LDH level, and receipt of thoracic RT or PCI. These findings support current treatment algorithms for ES-SCLC and provide baseline survival estimates to assess the real-world impact of adding immune checkpoint inhibitors in the future.

Real-world predictors of survival in patients with limited-stage small-cell lung cancer in Manitoba, Canada.

Background: Although therapy for limited-stage small-cell lung cancer (LS-SCLC) is administered with curative intent, most patients relapse and eventually die of recurrent disease. Chemotherapy (CT) with concurrent radiotherapy (RT) remains the standard of care for LS-SCLC; however, this could evolve in the near future. Therefore, understanding the current prognostic factors associated with survival is essential. Objective: This real-world analysis examines factors associated with long-term survival in patients with LS-SCLC treated with CT in Manitoba, Canada. Methods: A retrospective cohort study was conducted using Manitoba Cancer Registry and CancerCare Manitoba records. Eligible patients were aged >18 years and had cytologically confirmed LS-SCLC diagnosed between January 1, 2004, and December 31, 2018, for which they received CT ± RT. Baseline patient, disease, and treatment characteristics and survival duration, characterized as short (<6 months), medium (6-24 months), and long term (>24 months), were extracted. Overall survival (OS) was estimated at one, two, and five years and assessed using Kaplan-Meier methods and Cox proportional hazards models. Results: Over the 15-year study period, 304 patients met the eligibility criteria. Long-term survivors comprised 39.1% of the cohort; at diagnosis, this subgroup was younger, more likely to have Eastern Cooperative Oncology Group Performance Status (ECOG PS) 0, and have normal lactate dehydrogenase, sodium, and hemoglobin levels. OS estimates for the entire cohort at one, two, and five years were 66%, 38%, and 18%, respectively. In the ECOG PS 0 subgroup, OS estimates at one, two, and five years were 85%, 52%, and 24%, respectively; OS estimates were 60%, 35%, and 17%, respectively, for ECOG PS 1-2 and were 47%, 23%, and 10%, respectively, for ECOG PS 3-4. OS was significantly higher among patients with normal serum sodium and hemoglobin levels than those with abnormal levels. Univariable hazard regression models found that ECOG PS, age at diagnosis, receipt of prophylactic cranial irradiation (PCI), and thoracic RT were associated with survival. On multivariable hazard regression, ECOG PS and receipt of PCI were associated with survival. Conclusion: Survival for greater than two years in patients with LS-SCLC treated with CT ± RT was associated with ECOG PS and receipt of PCI.

Transcription factor NF-kappaB differentially regulates death receptor 5 expression involving histone deacetylase 1.

The transcription factor nuclear factor kappaB (NF-kappaB) regulates the expression of both anti-apoptotic and proapoptotic genes. Death receptor 5 (DR5, TRAIL-R2) is a proapoptotic protein considered to be a potential target for cancer therapy, and its expression is mediated by NF-kappaB. The mechanism of NF-kappaB-induced DR5 expression is, however, unknown. Herein, we determined that etoposide-induced DR5 expression requires the first intronic region of the DR5 gene. Mutation of a putative NF-kappaB binding site in this intron eliminates DR5 promoter activity, as do mutations in the p53 binding site in this region. Reduction in p53 expression also blocks p65 binding to the intronic region of the DR5 gene, indicating cooperation between p53 and p65 in DR5 expression. In contrast, the anti-apoptotic stimulus, epidermal growth factor (EGF), fails to increase DR5 expression but effectively activates NF-kappaB and induces p65 binding to the DR5 gene. EGF, however, induces the association of histone deacetylase 1 (HDAC1) with the DR5 gene, whereas etoposide treatment fails to induce this association. Indeed, HDAC inhibitors activate NF-kappaB and p53 and upregulate DR5 expression. Blockage of DR5 activation decreased HDAC inhibitor-induced apoptosis, and a combination of HDAC inhibitors and TRAIL increased apoptosis. This provides a mechanism for regulating NF-kappaB-mediated DR5 expression and could explain the differential roles NF-kappaB plays in regulating apoptosis.

Role of the TRAIL/APO2-L death receptors in chlorambucil- and fludarabine-induced apoptosis in chronic lymphocytic leukemia.

The standard treatments for chronic lymphocytic leukemia (CLL) include the alkylating agent chlorambucil (CLB) and the nucleoside analog fludarabine (F-ara-AMP, Flu). Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a death receptor ligand that induces apoptosis preferentially in tumors. However, CLL cells seem to be resistant to TRAIL-induced apoptosis. The TRAIL apoptotic signaling pathway has also been implicated in genotoxin-induced apoptosis through upregulation of TRAIL death receptors DR4 and DR5. In the present study, we demonstrate that the treatment of primary CLL cells with CLB or Flu increases the mRNA, protein and cell surface expression levels of DR4 and DR5 in a dose-dependent manner. In contrast to CLL cells, drug treatment fails to increase significantly the expression of DR4 or DR5 in normal lymphocytes. CLL cells are, however, resistant to TRAIL-induced apoptosis compared to B-cell lines. In contrast, combinational treatment using CLB or Flu with TRAIL (100 ng/ml) gave a synergistic apoptotic response. Furthermore, TRAIL is readily detectable on the cell surface of CLL cells, but TRAIL expression fails to increase following drug treatment. Preventing TRAIL from interacting with DR4 and DR5 decreases CLB-induced apoptosis in CLL cells. A similar, but less marked effect is observed with Flu. These findings indicate the involvement of the TRAIL apoptotic pathway in the mechanism of action of chemotherapy, and this mechanism could be utilized to sensitize CLL cells to TRAIL-induced apoptosis.

Cyclin D expression in chronic lymphocytic leukemia.

Although the majority of circulating leukemic cells in chronic lymphocytic leukemia (CLL) are in G0/early G1, recent studies have shown that these cells have undergone multiple cell divisions. In this study, we have determined whether there are abnormalities in cell cycle control in CLL by examining the three cyclin D isoforms in 43 patients and correlating the findings with clinical features. Cyclin D mRNA was measured by a sensitive RNase protection assay and the order of expression in CLL cells was D3 > D2 > D1. The mean cyclin D1 and D3 mRNA levels were 4 to 6-fold higher in CLL cells than in normal peripheral blood B cells. In contrast, the levels of cyclin D2 mRNA were similar in CLL and normal B cells. Expression of the cyclin D isoforms was two- to four-fold greater in normal T cells than B cells, and the order of expression for both cell types was D2 > D3 > D1. The relative overexpressions of cyclins D1 and D3 in CLL were unrelated to gene amplification, as assessed by Southern blotting, but structural changes in the genes were seen in four patients. Both cyclin D1 and D3 mRNA levels correlated positively with lymphocyte doubling time (LDT) and inversely with Rai stage and duration of disease. In addition, a significant correlation was observed between cyclin D mRNA levels and survival, with patients having high levels of cyclin D1, and to a lesser extent cyclin D3, mRNA having the best survival. Thus, cyclin D1 and D3 are relatively overexpressed in CLL cells and patients with higher levels have low stage disease, long LDT and prolonged survival. Further studies should evaluate the predictive value of cyclin D measurements in comparison to other prognostic markers in CLL.

Role of myeloid cell factor-1 (Mcl-1) in chronic lymphocytic leukemia.

The primary abnormality in chronic lymphocytic leukemia (CLL) is a defect in apoptosis, probably related to alterations in the expressions of Bcl-2 family members. In transgenic mice over expressing the anti-apoptotic Bcl-2 family member, myeloid cell factor-1 (Mcl-1), B cell lymphomas occur. Moreover, mice conditional for the loss of Mcl-1 display a profound reduction in B and T lymphocytes. This suggests that Mcl-1 is an essential survival factor in lymphocytes. In the present study, we have evaluated the role of Mcl-1 in CLL. Mcl-1 protein expression was measured by Western blot analysis in the CLL cells of 45 patients and correlated with clinical variables and survival. Mcl-1 levels were similar in 29 patients to normal B and T lymphocytes, were decreased in 8 patients and increased in 12 patients. An inverse correlation was found between Mcl-1 expression and Rai stage (P = 0.001). When assessed by flow cytometry, Mcl-1 expressions were normally distributed among CLL cells in individual patients and the mean levels correlated with those obtained by Western blotting. To evaluate the role of Mcl-1 in drug resistance, Mcl-1 levels were sequentially measured in the leukemic cells of 4 CLL patients during therapy with fludarabine (Flu). The Mcl-1 levels were found to increase in 2 patients while the peripheral blood lymphocyte counts dropped, suggesting that the residual drug-resistant cells had the highest Mcl-1 levels. Primary CLL cells were also treated with chlorambucil (CLB) or Flu in vitro and the Mcl-1 levels decreased correlating with the sensitivity of these cells to undergo apoptosis. Drug sensitivities of the CLL cells to CLB and Flu were also measured by MTT assay and the concentrations of drug required to decrease cell viability by 50% (IC50) varied from 1.9 to 9.27 microM for Flu (median, 9.4 microM) and 10 to 32.5 microM (median, 5.5 microM) for CLB. The sensitivities of the leukemic cells to CLB correlated inversely with Mcl-1 levels (P < 0.05). These results suggest that Mcl-1 may contribute to cell survival in CLL.