Differential association of STK11 and TP53 with KRAS mutation-associated gene expression, proliferation and immune surveillance in lung adenocarcinoma

While mutations in the KRAS oncogene are amongst the most prevalent in human cancer, there are few successful treatments to target these tumors. It is also likely that heterogeneity in KRAS-mutant tumor biology significantly contributes to the response to therapy. We hypothesized that presence of commonly co-occurring mutations in STK11 and TP53 tumor suppressors may represent a significant source of heterogeneity in KRAS-mutant tumors. To address this, we utilized a large cohort of resected tumors from 442 lung adenocarcinoma patients with data including annotation of prevalent driver mutations (KRAS, EGFR) and tumor suppressor mutations (STK11 and TP53), microarray-based gene expression and clinical covariates including overall survival (OS). Specifically, we determined impact of STK11 and TP53 mutations on a new KRAS mutation-associated gene expression signature as well as previously defined signatures of tumor cell proliferation and immune surveillance responses. Interestingly, STK11, but not TP53 mutations, were associated with highly elevated expression of KRAS mutation-associated genes. Mutations in TP53 and STK11 also impacted tumor biology regardless of KRAS status, with TP53 strongly associated with enhanced proliferation and STK11 with suppression of immune surveillance. These findings illustrate the remarkably distinct ways through which tumor suppressor mutations may contribute to heterogeneity in KRAS-mutant tumor biology. In addition, these studies point to novel associations between gene mutations and immune surveillance that could impact the response to immunotherapy.

IKBKE is induced by STAT3 and tobacco carcinogen and determines chemosensitivity in non-small cell lung cancer

Serine/threonine kinase IKBKE is a newly identified oncogene; however, its regulation remains elusive. Here, we provide evidence that IKBKE is a downstream target of signal transducer and activator of transcription 3 (STAT3) and that tobacco components induce IKBKE expression through STAT3. Ectopic expression of constitutively active STAT3 increased IKBKE mRNA and protein levels, whereas inhibition of STAT3 reduced IKBKE expression. Furthermore, expression levels of IKBKE are significantly associated with STAT3 activation and tobacco use history in non-small cell lung cancer (NSCLC) patients examined. In addition, we show induction of IKBKE by two components of cigarette smoke, nicotine and nicotine-derived nitrosamine ketone (NNK). Upon exposure to nicotine or NNK, cells express high levels of IKBKE protein and mRNA, which are largely abrogated by inhibition of STAT3. Characterization of the IKBKE promoter revealed two STAT3-response elements. The IKBKE promoter directly bound to STAT3 and responded to nicotine and NNK stimulation. Notably, enforcing expression of IKBKE induces chemoresistance, whereas knockdown of IKBKE not only sensitizes NSCLC cells to chemotherapy but also abrogates STAT3- and nicotine-induced cell survival. These data indicate for the first time that IKBKE is a direct target of STAT3 and is induced by tobacco carcinogens through STAT3 pathway. In addition, our study also suggests that IKBKE is an important therapeutic target and could have a pivotal role in tobacco-associated lung carcinogenesis.

Survival predictors after surgical resection of synchronous bilateral non-small cell lung cancers (NSCLC)

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Background: Non-small cell lung cancer (NSCLC) that presents with bilateral lung lesions, but without extra-thoracic metastasis, is uncommon. Prognosis is typically poor: No long-term survivor is expected with systemic chemotherapy. However, small reports have suggested the feasibility of bilateral resections. To date, the predictors of survival following this treatment approach remain unknown. Methods: Our institutional tumor registry was searched for patients who underwent bilateral resections of NSCLC during 1998–2006. Patients with metachronous presentations (second lesion found ≥ 2 years afterward) were excluded. Kaplan-Meier survival estimate and Cox proportional hazards model were used to identify survival predictors. Results: Of the 2582 patients operated for NSCLC, 50 patients were included in this analysis. Median age was 69.2 years. Median tumor sizes were 2.0 cms; Adenocarcinomas were the most common (51%). Of 103 thoracotomies, pneumonectomy was performed in 3 patients. Overall peri-operative mortality was 1.9%. Median progression-free survival was 46.0 months (95% CI, 33.1–66.6); overall survival was 77.5 months (95% CI, 43.1–111.1). Performance status, presence of comorbidity, and pathological vascular invasion were important prognostic factors (Table). Risk score based on the sum of these factors (present =1; absent =0) was a strong predictor of survival. Patients with score ≥ 2 (N=11) had a median survival of 17.2 months, compared with 83.5 months among those with score ≤ 1 (HR 5.52, 95% CI 2.27–13.46; p=0.0002). Conclusions: In this largest series of surgery for synchronous bilateral NSCLC to date, the overall survival rate at 5 years is approximately 50%. Performance status, comorbidity, and vascular invasion are strong predictors of survival. Patients with vascular invasion are at an increased risk of progression or death and adjuvant therapy should be considered.

[Table: see text]

No significant financial relationships to disclose.

Evidence for long-term survival in a sizeable proportion of good performance status (PS) patients (pts) with advanced non-small cell lung cancer (NSCLC)

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Background: Approximately 40% of NSCLC pts present with metastatic disease where treatment is considered palliative. Here we examine whether prolonged survival is possible in a sizeable proportion of NSCLC pts with good PS and stage IV disease particularly given the availability of personalized chemotherapy approaches. Methods: NSCLC pts with stage IV disease and an ECOG PS of 0/1 were prospectively accrued to four phase II clinical trials, at the H. Lee Moffitt Cancer Center and treated with the following regimens; Trial A) carboplatin/gemcitabine first-line followed by docetaxel second-line, Trial B) docetaxel and gefitinib combination therapy in patients aged 70 years or older, Trial C) combination therapy with carboplatin/paclitaxel/atrasentan, Trial D) personalized therapy (PT) based on ERCC1 and RRM1. Pts with low RRM1/low ERCC1 received gemcitabine/carboplatin; low RRM1/high ERCC1, gemcitabine/docetaxel; high RRM1/low ERCC, docetaxel/carboplatin; high RRM1/high ERCC1, vinorelbine/docetaxel. Data were updated as of 10/23/08. Overall survival was estimated using the piecewise exponential survival function which showed a dramatic shift at 29 months. Results: A total number of 181 pts were accrued. The median survival for the entire cohort was 10.5 months improving dramatically to 85.3 months, if alive at 29 months (adjusted P = 0.005). In the entire cohort, 16.7% of pts survived to 29 months compared to 25% of pts in the PT group. For pts who were alive at 29 months, the probabilities of surviving to 48, 60, 72 and 84 months were 79%, 68%, 59% and 51%, respectively. Conclusions: Long term survival is possible in a sizeable proportion of stage IV NSCLC with good PS. Our treatment paradigm should shift from palliation to achieving long term survival. Molecularly-based PT may be one way of achieving this goal.

No significant financial relationships to disclose.

Phase II trial of docetaxel (D) plus gefitinib (G) in elderly (≥70 years) patients with advanced stage non-small cell lung cancer (ANSCLC)

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Background: Adding G to first-line doublet chemotherapy did not improve survival in comparison to doublet chemotherapy alone in phase III trials (INTACT 1 and INTACT2). We hypothesized that therapy with D and G will yield similar efficacy to doublet chemotherapy but with improved toxicity profile that would be especially meaningful for elderly patients. We report here the results of a completed phase II trial. Methods: Previously untreated elderly patients with ANSCLC with ECOG performance status (PS) of 0 or 1, were eligible. D was given at 75 mg/m2 IV on day1, Q 21 days. G given orally daily; starting day 1, at a dose of 250mg. D-G was given for 2 cycles beyond maximal response. G was continued until progression. Tumors were assessed every two cycles while on D-G and every two months while on G. The RECIST criteria were used to measure responses. Results: Forty-four eligible patients were enrolled from 07/2003 to 11/2005. Demographic characteristics were M/F = 25/19; Median age 75 years (range; 70 to 84 years); ECOG PS 0/1= 27/16; Stage IV/IIIB = 38/6; Never-smoker/smoker 8/36; Adenocarcinoma/non-adeno-NSCLC 30/14; Median number of D-G cycles administered is 4 (range; 1 to 6). Median duration on maintenance D was 5 months (range; 1 to 36) Overall response rate was 29% (CR- 2%; PR- 27%) with 48% stable disease. Median progression free survival (PFS) was 8 months (95% CI: 6.2–10.6), PFS at 12 months was 34%, and 24 months was 19%. Median Overall Survival (OS) was 12 months (95% CI: 5.6–17.5). OS at 12 months was 52% and 24 months was 20%. The most common hematologic and non- hematologic adverse events were lymphopenia/anemia, and fatigue/hyperglycemia (steroid-induced)/dyspnea, respectively. Three patients had febrile neutropenia (6.8%). Detailed toxicity analyses will be reported at the meeting. Conclusion: The combination of D and G demonstrates comparable efficacy to conventionally used doublet chemotherapy regimens. The relatively favorable toxicity profile warrants further development of this approach, especially in clinical situations or special populations where toxicities are an impediment to treatment.

No significant financial relationships to disclose.

Dose-dense pemetrexed (P) and gemcitabine (G) as neoadjuvant therapy in resectable non-small cell lung cancer (NSCLC)

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Background: Adjuvant chemotherapy is standard of care for NSCLC stage IB-III after complete resection. Neoadjuvant therapy has potential advantages. P and G are efficacious in NSCLC with low toxicity. In combination, they can be given dose-dense, which may result in better efficacy, lower toxicity, and higher patient acceptability than traditional platinum-based therapy. Methods: Patients with resectable IB-IIIA and selected IIIB, PS 0–1, w/o prior therapy were eligible. CT, PET, brain MRI, and mediastinoscopy were used for staging. P (500 mg/m2) and G (1,500 mg/m2) were given on d1, 15, 29, and 43. Imaging studies were repeated 7–14 days after treatment and response determined by RECIST. Patients had surgery 3–4 weeks after the last treatment. F/U was every 3 months for 2 years with imaging studies. The primary clinical endpoint is radiographic disease response rate. The secondary endpoints are overall and disease-free survival, pathologic response rate, treatment-related toxicity, and surgical respectability and outcome Results: From 4/04 to 12/05, 45 eligible patients were enrolled. The disease stages were IB in 17, IIA in 3, IIB in 10, IIIA in 12, and IIIB in 3 patient. 8 had adeno, 15 squamous, and 22 large cell or unspecified NSCLC on initial diagnosis. 27 had a PS of 0 and 18 PS 1. 3/45 had weight loss. 22 were women. The median age was 67 (range 42–83 years). 2 were never-smokers, 24 had quit, and 19 were active smokers. Disease response rates to PG were 3% CR, 34% PR, 55% SD, and 8% PD. An R0 resection was performed in 75% of patients, 15% had an incomplete resection, and 10% did not have a thoracotomy. There have been no deaths or unexpected morbidities related to surgery or chemotherapy. Conclusions: Dose-dense PG is well tolerated with acceptable side effects. It appears to be equally as efficacious as platinum-containing chemotherapy doublets in terms of radiographic response rates. Survival rates and the median survival time are forthcoming to allow for a better comparison of this regimen with platinum-containing doublets.

No significant financial relationships to disclose.

Phosphotyrosyl peptides block Stat3-mediated DNA binding activity, gene regulation, and cell transformation

Signal transducers and activators of transcription (STATs) comprise a family of cytoplasmic signaling proteins that participates in normal cellular responses to cytokines and growth factors. Frequently, however, constitutive activation of certain STAT family members, particularly Stat3, has accompanied a wide variety of human malignancies. To identify small molecule inhibitors of Stat3, we investigated the ability of the Stat3 SH2 domain-binding peptide, PY*LKTK (where Y* represents phosphotyrosine), to disrupt Stat3 activity in vitro. The presence of PY*LKTK, but not PYLKTK or PFLKTK, in nuclear extracts results in significant reduction in the levels of DNA binding activities of Stat3, to a lesser extent of Stat1, and with no effect on that of Stat5. Analyses of alanine scanning mutagenesis and deletion derivatives of PY*LKTK reveal that the Leu residue at the Y+1 position and a substituent at the Y-1 position (but not necessarily Pro) are essential for the disruption of active Stat3, thereby mapping the minimum active sequence to the tripeptide, XY*L. Studies involving bead-coupled PY*LKTK peptide demonstrate that this phosphopeptide directly complexes with Stat3 monomers in vitro, suggesting that PY*LKTK disrupts Stat3:Stat3 dimers. As evidence for the functional importance of peptide-directed inhibition of Stat3, PY*LKTK-mts (mts, membrane translocating sequence) selectively inhibits constitutive and ligand-induced Stat3 activation in vivo. Furthermore, PY*LKTK-mts suppresses transformation by the Src oncoprotein, which has been shown previously to require constitutive Stat3 activation. Altogether, we have identified a minimal peptide that inhibits Stat3 signaling and provides the conceptual basis for use of this peptide as a lead for novel peptidomimetic drug design.

Treatment of advanced non-small-cell lung cancer: a review of current randomized clinical trials and an examination of emerging therapies

BACKGROUND

Lung cancer continues to be the leading cause of cancer-related deaths for Americans. As most patients present with nonsurgically curable disease, major efforts have been made in the treatment of advanced non-small-cell lung cancer (NSCLC) with chemotherapy. Several new agents and new combinations of chemotherapy are available.

METHODS

The author reviews randomized clinical trials investigating chemotherapy for advanced NSCLC in chemotherapy-naive patients, in patients who present with relapsed or progressive disease, and in elderly patients. Therapies that incorporate new biological agents to target specific aberrations in lung cancer are discussed.

RESULTS

Several clinical trials demonstrate improvement in overall survival as well as quality of life with chemotherapy treatment of advanced NSCLC. Better options are available for patients who have relapsed after first-line chemotherapy, and treatment of elderly patients with chemotherapy has demonstrated benefit in survival and quality of life. New agents that target molecular pathways are being tested in patients with early-stage disease.

CONCLUSIONS

Despite progress with newer agents for the treatment of advanced NSCLC, only 14% of patients with the disease are alive at 5 years after initial diagnosis. New therapies are needed.

Multiple Ras-dependent phosphorylation pathways regulate Myc protein stability

Our recent work has shown that activation of the Ras/Raf/ERK pathway extends the half-life of the Myc protein and thus enhances the accumulation of Myc activity. We have extended these observations by investigating two N-terminal phosphorylation sites in Myc, Thr 58 and Ser 62, which are known to be regulated by mitogen stimulation. We now show that the phosphorylation of these two residues is critical for determining the stability of Myc. Phosphorylation of Ser 62 is required for Ras-induced stabilization of Myc, likely mediated through the action of ERK. Conversely, phosphorylation of Thr 58, likely mediated by GSK-3 but dependent on the prior phosphorylation of Ser 62, is associated with degradation of Myc. Further analysis demonstrates that the Ras-dependent PI-3K pathway is also critical for controlling Myc protein accumulation, likely through the control of GSK-3 activity. These observations thus define a synergistic role for multiple Ras-mediated phosphorylation pathways in the control of Myc protein accumulation during the initial stage of cell proliferation.