Improving the efficacy of immunotherapy in small cell lung cancer: Leveraging recent scientific discoveries and tumor-specific antigens.

Small cell lung cancer (SCLC) is an aggressive neuroendocrine neoplasm with poor survival outcomes and little change to treatment standards over decades. SCLC is associated with heavy tobacco exposure and a high rate of somatic mutations in tumor cells, leading to hope that immune checkpoint inhibitors would dramatically reshape the treatment landscape of SCLC. Instead, immune checkpoint inhibitors have led to real but modest gains in outcomes, with only a small minority of patients deriving more durable benefit. Furthermore, biomarkers of ICI efficacy that have succeeded in other tumor types have not been validated in SCLC. However, recent research advances have suggested that epigenetic heterogeneity and plasticity play especially key roles in SCLC biology. Leveraging this emerging perspective, a new slate of candidate biomarkers of immune checkpoint inhibitor benefit have been described, and the novel treatment strategies combining rational epigenetic perturbation with immune checkpoint inhibitors are being developed. Finally, other immunotherapy strategies targeting SCLC-specific mechanisms are being tested. Together, these developments may lead to a second generation of much more efficacious immunotherapies in SCLC.

Venetoclax and Decitabine for T/Myeloid Mixed-Phenotype Acute Leukemia Not Otherwise Specified (MPAL NOS).

T/myeloid mixed-phenotype acute leukemia not otherwise specified (MPAL NOS) is an uncommon and aggressive leukemia without well-established treatment guidelines, particularly when relapsed. Venetoclax plus a hypomethylating agent offers a promising option in this situation since studies support its use in both acute myeloid and, albeit with fewer data to date, acute T-cell-lymphoblastic leukemias. We report the successful eradication of T/myeloid MPAL NOS relapsed after allogeneic stem cell transplant with venetoclax plus decitabine. A consolidative allogeneic stem cell transplant from a second donor was subsequently performed, and the patient remained without evidence of disease more than one year later. Further investigation is indicated to evaluate venetoclax combined with hypomethylating agents and/or other therapies for the management of T/myeloid MPAL NOS.

Salvaging of a failed Lapidus procedure by the soft tissue osteodesis procedure: A six-year follow-up case report.

Soft tissue approach to hallux valgus deformity correction has not been popular due to concerns of its effectiveness. Osteodesis procedure is a soft tissue technique that has been reported with favorable results, especially its long term deformity recurrence rate was very low. Recurrence complication after Lapidus procedure has seldom been reported and its remedial surgery not much discussed yet. Soft tissue approach has never been recommended or reported for salvaging failed hallux valgus surgery. This case report is a failed Lapidus procedure due to symptomatic recurrence of deformity that was successfully salvaged by osteodesis procedure and followed up for six years to ensure no late symptoms and deformity recurrence.

Osteodesis for hallux valgus correction: is it effective?

BACKGROUND: Although the etiology of hallux valgus is contested, in some patients it may be failure of the stabilizing soft tissue structures around the first ray of the foot. Because there is lack of effective soft tissue techniques, osteotomies have become the mainstream surgical approach to compensate for the underlying soft tissue deficiency; osteodesis, a soft tissue nonosteotomy technique, may be a third alternative, but its efficacy is unknown. QUESTIONS/PURPOSES: We asked: (1) Can an osteodesis, a distal soft tissue technique, correct hallux valgus satisfactorily in terms of deformity correction and improvement in American Orthopaedic Foot and Ankle Society (AOFAS) score? (2) Is the effectiveness of an osteodesis affected by the patient's age or deformity severity? (3) What complications are associated with this procedure? METHODS: Between February and October 2010, we performed 126 operations to correct hallux valgus, of which 126 (100%) were osteodeses. Sixty-one patients (110 procedures) (87% of the total number of hallux valgus procedures) were available for followup at a minimum of 12 months (mean, 23 months; range, 12-38 months). This group formed our study cohort. During the study period, the general indications for this approach included failed conservative measures for pain relief and metatarsophalangeal angle greater than 20° or intermetatarsal angle greater than 9°. Intermetatarsal cerclage sutures were used to realign the first metatarsal and postoperative fibrosis was induced surgically between the first and second metatarsals to maintain its alignment. The radiologic first intermetatarsal angle, metatarsophalangeal angle, and medial sesamoid position were measured by Hardy and Clapham's methods for deformity and correction evaluation. Clinical results were assessed by the AOFAS score. RESULTS: The intermetatarsal angle was improved from a preoperative mean of 14° to 7° (p<0.001; Cohen's d=1.8) at followup, the metatarsophalangeal angle from 31° to 18° (p<0.001; Cohen's d=3.1), the medial sesamoid position from position 6 to 3 (p<0.001; Cohen's d=2.4), and AOFAS hallux score from 68 to 96 points (p<0.001). Neither patient age nor deformity severity affected the effectiveness of the osteodesis in correcting all three radiologic parameters; however, the deformities treated in this series generally were mild to moderate (mean intermetatarsal angle, 14°; range, 9°-22°). There were six stress fractures of the second metatarsal (5%), five temporary metatarsophalangeal joint medial subluxations all resolved in one month by the taping-reduction method without surgery, and six metatarsophalangeal joints with reduced dorsiflexion less than 60°. CONCLUSIONS: The osteodesis is a soft tissue nonosteotomy technique, and provided adequate deformity correction and improvement in AOFAS scores for patients with mild to moderate hallux valgus deformities, although a small number of the patients had postoperative stress fractures of the second ray develop. Future prospective studies should compare this technique with osteotomy techniques in terms of effectiveness of the correction, restoration of hallux function, complications, and long-term recurrence. LEVEL OF EVIDENCE: Level IV, therapeutic study. See the Instructions for Authors for a complete description of levels of evidence.

Polyploidy road to therapy-induced cellular senescence and escape.

Therapy-induced cellular senescence (TCS), characterized by prolonged cell cycle arrest, is an in vivo response of human cancers to chemotherapy and radiation. Unfortunately, TCS is reversible for a subset of senescent cells, leading to cellular reproliferation and ultimately tumor progression. This invariable consequence of TCS recapitulates the clinical treatment experience of patients with advanced cancer. We report the findings of a clinicopathological study in patients with locally advanced non-small cell lung cancer demonstrating that marker of in vivo TCS following neoadjuvant therapy prognosticate adverse clinical outcome. In our efforts to elucidate key molecular pathways underlying TCS and cell cycle escape, we have previously shown that the deregulation of mitotic kinase Cdk1 and its downstream effectors are important mediators of survival and cell cycle reentry. We now report that aberrant expression of Cdk1 interferes with apoptosis and promotes the formation of polyploid senescent cells during TCS. These polyploid senescent cells represent important transition states through which escape preferentially occurs. The Cdk1 pathway is in part modulated differentially by p21 and p27 two members of the KIP cyclin-dependent kinase inhibitor family during TCS. Altogether, these studies underscore the importance of TCS in cancer therapeutics.

Comparison of demographic characteristics, surgical resection patterns, and survival outcomes for veterans and nonveterans with non-small cell lung cancer in the Pacific Northwest.

INTRODUCTION: Lung cancer is a leading cause of death in the United States and among veterans. This study compares patterns of diagnosis, treatment, and survival for veterans diagnosed with non-small cell lung cancer (NSCLC) using a recently established cancer registry for the Veterans Affairs Pacific Northwest Network with the Puget Sound Surveillance, Epidemiology, and End Results cancer registry. METHODS: A cohort of 1715 veterans with NSCLC were diagnosed between 2000 and 2006, and 7864 men were diagnosed in Washington State during the same period. Demographics, tumor characteristics, initial surgical patterns, and survival across the two registries were evaluated. RESULTS: Veterans were more likely to be diagnosed with stage I or II disease (32.8%) compared with the surrounding community (21.5%, p = 0.001). Surgical resection rates were similar for veterans (70.2%) and nonveterans (71.2%) older than 65 years with early-stage disease (p = 0.298). However, veterans younger than 65 years with early-stage disease were less likely to undergo surgical resection (83.3% versus 91.5%, p = 0.003). Because there were fewer late-stage patients among veterans, overall survival was better, although within each stage group veterans experienced worse survival compared with community patients. The largest differences were among early-stage patients with 44.6% 5-year survival for veterans compared with 57.4% for nonveterans (p = 0.004). CONCLUSIONS: The use of surgical resection among younger veterans with NSCLC may be lower compared with the surrounding community and may be contributing to poorer survival. Cancer quality of care studies have primarily focused on patients older than 65 years using Medicare claims; however, efforts to examine care for younger patients within and outside the Department of Veterans Affairs are needed.

Survivin and escaping in therapy-induced cellular senescence.

Therapy-induced accelerated cellular senescence (ACS) is a reversible tumor response to chemotherapy that is likely detrimental to the overall therapeutic efficacy of cancer treatment. To further understand the mechanism by which cancer cells can escape the sustained cell cycle arrest in ACS, we established a tissue culture model, in which the p53-null NCI-H1299 cells can be induced into senescence by an abbreviated exposure to a chemotherapeutic agent. Previously, we have reported that senescent cells overexpress Cdc2/Cdk1 when they bypassed the prolonged arrest and their viability is dependent on Cdc2/Cdk1 kinase activity. In our study, we show that human survivin is the immediate downstream effector of the Cdc2/Cdk1 mediated survival signal. Survivin cooperates with Cdc2/Cdk1 to inhibit apoptosis following chemotherapy and promote senescence escape. Using HIV-1 TAT peptides to disrupt survivin phosphorylation by Cdc2/Cdk1, we also found that phosphorylated survivin is necessary both for the escape of senescent cells and for maintenance of subsequent viability after bypassing senescence. These results further propose survivin as an important determinant of senescence reversibility and as a putative molecular target to enforce cell death in ACS.

TLS-ERG leukemia fusion protein deregulates cyclin-dependent kinase 1 and blocks terminal differentiation of myeloid progenitor cells.

TLS-ERG fusion protein is derived from the t(16;21) translocation found in human myeloid leukemia. Here, we show that retroviral transduction of TLS-ERG confers a growth advantage to L-G myeloid progenitor cells and blocks terminal differentiation. We found that the level of cyclin-dependent kinase 1 (Cdk1) protein was significantly decreased in controls but unchanged in TLS-ERG-expressing cells after granulocyte colony-stimulating factor treatment or interleukin-3 withdrawal. Injection of TLS-ERG-expressing L-G cells induced rapid development of a leukemia-like disease in syngeneic mice. Through site-directed mutagenesis, we showed that transformation and deregulation of Cdk1 by TLS-ERG require an intact ets DNA-binding domain within the fusion protein. Interestingly, treatment of TLS-ERG-expressing L-G cells with 5-aza-2'-deoxycytidine (Decitabine) or trichostatin A resulted in down-regulation of Cdk1 and induction of terminal differentiation. To investigate whether Cdk1 deregulation is indeed responsible for transformation by TLS-ERG, we constructed lentiviral vectors for delivery of Cdk1 mutants and small interfering RNA (siRNA). Both dominant-negative inhibition and siRNA knockdown of Cdk1 were able to restore the ability of TLS-ERG-expressing L-G cells to undergo terminal differentiation. In addition, siRNA knockdown of Cdk1 in YNH-1 cells derived from a t(16;21) acute myelogenous leukemia patient also resulted in terminal differentiation. As restoration of terminal myeloid differentiation to TLS-ERG cells is dependent on cell cycle arrest, our findings suggest an important role for Cdk1 in cellular transformation and may be useful in the search for new treatments of TLS-ERG-associated myeloid leukemia.

EWS/FLI1 suppresses retinoblastoma protein function and senescence in Ewing's sarcoma cells.

Ewing's Family Tumors (EFTs) most commonly harbor a specific t(11;22) translocation that generates the EWS/FLI1 fusion protein responsible for malignant transformation. Many potential downstream targets of EWS/FLI1 have been identified but a detailed mechanism by which the fusion protein brings about transformation remains unknown. In this report, we show that depletion of EWS/FLI1 in Ewing's cell lines results in a senescence phenotype, a marked increase in expression of the G1/S regulatory proteins p27(kip1) and p57(kip2), and a significant decrease in cyclin D1 and CDK2. We also demonstrate for the first time, to our knowledge, that knockdown of EWS/FLI1 leads to hypophosphorylation and functional activation of the retinoblastoma (pRb) family of proteins. Consistent with activation of the pRb proteins, E2F-responsive genes such as cyclin A are repressed in EWS/FLI1-depleted cells. Together, these results support the role of EWS/LI1 as an inhibitor of cellular senescence and implicate the retinoblastoma family of proteins as key mediators of this inhibition.

Escape from therapy-induced accelerated cellular senescence in p53-null lung cancer cells and in human lung cancers.

Accelerated cellular senescence (ACS) has been described for tumor cells treated with chemotherapy and radiation. Following exposure to genotoxins, tumor cells undergo terminal growth arrest and adopt morphologic and marker features suggestive of cellular senescence. ACS is elicited by a variety of chemotherapeutic agents in the p53-null, p16-deficient human non-small cell H1299 carcinoma cells. After 10 to 21 days, infrequent ACS cells (1 in 10(6)) can bypass replicative arrest and reenter cell cycle. These cells express senescence markers and resemble the parental cells in their transcription profile. We show that these escaped H1299 cells overexpress the cyclin-dependent kinase Cdc2/Cdk1. The escape from ACS can be disrupted by Cdc2/Cdk1 kinase inhibitors or by knockdown of Cdc2/Cdk1 with small interfering RNA and can be promoted by expression of exogenous Cdc2/Cdk1. We also present evidence that ACS occurs in vivo in human lung cancer following induction chemotherapy. Viable tumors following chemotherapy also overexpress Cdc2/Cdk1. We propose that ACS is a mechanism of in vivo tumor response and that mechanisms aberrantly up-regulate Cdc2/Cdk1 promotes escape from the senescence pathway may be involved in a subset of tumors and likely accounts for tumor recurrence/progression.

Human BAG-1 proteins bind to the cellular stress response protein GADD34 and interfere with GADD34 functions.

The cellular stress response protein GADD34 mediates growth arrest and apoptosis in response to DNA damage, negative growth signals, and protein malfolding. GADD34 binds to protein phosphatase PP1 and can attenuate the translational elongation of key transcriptional factors through dephosphorylation of eukaryotic initiation factor 2alpha (eIF2alpha). Recently, we reported the involvement of human SNF5/INI1 (hSNF5/INI1) protein in the functions of GADD34 and showed that hSNF5/INI1 binds GADD34 and stimulates the bound PP1 phosphatase activity. To better understand the regulatory and functional mechanisms of GADD34, we undertook a yeast two-hybrid screen with full-length GADD34 as bait in order to identify additional protein partners of GADD34. We report here that human cochaperone protein BAG-1 interacts with GADD34 in vitro and in SW480 cells treated with the proteasome inhibitor z-LLL-B to induce apoptosis. Two other proteins, Hsp70/Hsc70 and PP1, associate reversibly with the GADD34-BAG-1 complex, and their dissociation is promoted by ATP. BAG-1 negatively modulates GADD34-bound PP1 activity, and the expression of BAG-1 isoforms can also mask GADD34-mediated inhibition of colony formation and suppression of transcription. Our findings suggest that BAG-1 may function to suppress the GADD34-mediated cellular stress response and support a role for BAG-1 in the survival of cells undergoing stress.

The human SNF5/INI1 protein facilitates the function of the growth arrest and DNA damage-inducible protein (GADD34) and modulates GADD34-bound protein phosphatase-1 activity.

The growth arrest and DNA damage-inducible protein (GADD34) mediates growth arrest and apoptosis in response to DNA damage, negative growth signals, and protein malfolding. GADD34 binds to protein phosphatase-1 (PP1) and can attenuate translational elongation of key transcriptional factors through dephosphorylation of eukaryotic initiation factor-2alpha. We reported previously that the human trithorax leukemia fusion protein (HRX) can bind to GADD34 and abrogate GADD34-mediated apoptosis in response to UV irradiation. We found that hSNF5/INI1, a component of the hSWI/SNF chromatin remodeling complex, also binds to GADD34 and can coexist with GADD34 and HRX fusion proteins as a trimolecular complexes in vivo. In the present report, we demonstrate that hSNF5/INI1 binds to GADD34 in part through the PP1 docking site within a domain homologous to herpes simplex virus-1 ICP34.5. We found that hSNF5/INI1 can bind PP1 independently and weakly stimulate its phosphatase activity in solution and in complex with GADD34. hSNF5/INI1 and PP1 do not compete for binding to GADD34 but rather form a stable heterotrimeric complex with GADD34. We also show that Epstein-Barr nuclear protein 2, which binds hSNF5/INI1, can disrupt hSNF5/INI1 binding to GADD34 and partially reverse the GADD34-mediated growth suppression function in Ha-ras expressing HIH-3T3 (3T3-ras) cells. These results implicate hSNF5/INI1 in the function of GADD34 and suggest that hSNF5/INI1 may regulate PP1 activity in vivo.

Molecular cloning of ESET, a novel histone H3-specific methyltransferase that interacts with ERG transcription factor.

The ets-related gene erg encodes a transcription factor that is implicated in the control of cell growth and differentiation. To identify interacting partners of ERG, we screened a yeast two-hybrid cDNA library constructed from mouse hematopoietic cells using the N-terminal region of ERG as a bait. We isolated a 4.6 kb full-length mouse cDNA encoding a 1307-amino acid protein migrating as a 180 kD band, which was termed ESET (ERG-associated protein with SET domain). ESET is 92% identical to the human protein SETDB1 (SET domain, bifurcated 1). The interaction between ESET and ERG was supported by in vitro pull-down using glutathione S-transferase (GST) fusion protein, by transfection and co-immunoprecipitation experiments, and by association of endogenous SETDB1 with ERG. Since ESET possesses evolutionarily conserved SET, preSET, and postSET domains implicated in histone methylation, we tested the ability of ESET to methylate core histones. The results of these studies demonstrated that ESET is a histone H3-specific methyltransferase, and that mutations within ESET abolished its methyltransferase activity. Together, these findings raise the possibility that transcription factor ERG may participate in transcriptional regulation through ESET-mediated histone methylation.