Modern era systemic therapies: Expanding concepts of cure in early and locally advanced non-small cell lung cancer.

Cure of cancer is a sensitive and multidimensional concept that is challenging to define, difficult to assert at the individual patient level, and often surrounded by controversy. The notion of cure in non-small cell lung cancer (NSCLC) has changed and continues to evolve with improvements in diagnosis and treatment. Targeted and immune therapies have recently entered the treatment landscape of stage I-III NSCLC. While some initial pivotal trials of such agents failed to improve survival, recently approved epidermal growth factor receptor (EGFR) inhibitors (in EGFR-mutated NSCLC) and immune checkpoint inhibitors have shown delays in disease recurrence or progression and unprecedented survival gains compared to previous standards of care. Additional data is now emerging supporting the benefit of treatment strategies based on alternation-matched targeting (anaplastic lymphoma kinase [ALK] inhibition in ALK-altered disease) and immune checkpoint inhibition in stage I-III NSCLC. Similar to previous developments in the treatment of early and locally advanced NSCLC, it is expected that statistically significant and clinically meaningful trial-level benefits will translate into real-world benefits, including improvements in cure measures. Parallel advances in molecular testing (e.g., circulating tumor DNA analyses) are also allowing for a deeper and more comprehensive characterization of disease status and treatment response. Given the impact that curative-intent treatments have on survival, it is critical that various stakeholders, including clinicians and patients, are aware of new opportunities to pursue cure in stage I-III NSCLC.

Circulating tumor cells detected in follow-up predict survival outcomes in tri-modality management of advanced non-metastatic esophageal cancer: a secondary analysis of the QUINTETT randomized trial.

BACKGROUND: Our aim was to establish if presence of circulating tumor cells (CTCs) predicted worse outcome in patients with non-metastatic esophageal cancer undergoing tri-modality therapy. METHODS: We prospectively collected CTC data from patients with operable non-metastatic esophageal cancer from April 2009 to November 2016 enrolled in our QUINTETT esophageal cancer randomized trial (NCT00907543). Patients were randomized to receive either neoadjuvant cisplatin and 5-fluorouracil (5-FU) plus radiotherapy followed by surgical resection (Neoadjuvant) or adjuvant cisplatin, 5-FU, and epirubicin chemotherapy with concurrent extended volume radiotherapy following surgical resection (Adjuvant). CTCs were identified with the CellSearch® system before the initiation of any treatment (surgery or chemoradiotherapy) as well as at 6-, 12-, and 24-months post-treatment. The threshold for CTC positivity was one and the findings were correlated with patient prognosis. RESULTS: CTC data were available for 74 of 96 patients and identified in 27 patients (36.5%) at a median follow-up of 13.1months (interquartile range:6.8-24.1 months). Detection of CTCs at any follow-up visit was significantly predictive of worse disease-free survival (DFS;hazard ratio [HR]: 2.44; 95% confidence interval [CI]: 1.41-4.24; p=0.002), regional control (HR: 6.18; 95% CI: 1.18-32.35; p=0.031), distant control (HR: 2.93; 95% CI: 1.52-5.65;p=0.001) and overall survival (OS;HR: 2.02; 95% CI: 1.16-3.51; p=0.013). After adjusting for receiving neoadjuvant vs. adjuvant chemoradiotherapy, the presence of CTCs at any follow-up visit remained significantly predictive of worse OS ([HR]:2.02;95% [Cl]:1.16-3.51; p=0.013) and DFS (HR: 2.49;95% Cl: 1.43-4.33; p=0.001). Similarly, any observed increase in CTCs was significantly predictive of worse OS (HR: 3.14; 95% CI: 1.56-6.34; p=0.001) and DFS (HR: 3.34; 95% CI: 1.67-6.69; p<0.001). CONCLUSION: The presence of CTCs in patients during follow-up after tri-modality therapy was associated with significantly poorer DFS and OS regardless of timing of chemoradiotherapy.

Cancer: Towards a general theory of the target: All successful cancer therapies, actual or potential, are reducible to either (or both) of two fundamental strategies.

General theories (GT) are reductionist explications of apparently independent facts. Here, in reviewing the literature, I develop a GT to simplify the cluttered landscape of cancer therapy targets by revealing they cluster parsimoniously according to only a few underlying principles. The first principle is that targets can be only exploited by either or both of two fundamentally different approaches: causality-inhibition, and 'acausal' recognition of some marker or signature. Nonetheless, each approach must achieve both of two separate goals, efficacy (reduction in cancer burden) and selectivity (sparing of normal cells); if the mechanisms are known, this provides a definition of rational treatment. The second principle is target fragmentation, whereby the target may perform up to three categoric functions (cytoreduction, modulation, cytoprotection), potentially mediated by physically different target molecules, even on different cell types, or circulating freely. This GT remains incomplete until the minimal requirements for cure, or alternatively, proof that cure is impossible, become predictable.

Synergistic Antiproliferative Activity of the RAD51 Inhibitor IBR2 with Inhibitors of Receptor Tyrosine Kinases and Microtubule Protein.

Although cancer cell genetic instability contributes to characteristics that mediate tumorigenicity, it also contributes to the tumor-selective toxicity of some chemotherapy drugs. This synthetic lethality can be enhanced by inhibitors of DNA repair. To exploit this potential Achilles heel, we tested the ability of a RAD51 inhibitor to potentiate the cytotoxicity of chemotherapy drugs. 2-(Benzylsulfonyl)-1-(1H-indol-3-yl)-1,2-dihydroisoquinoline (IBR2) inhibits RAD51-mediated DNA double-strand break repair but also enhances cytotoxicity of the Bcr-Abl inhibitor imatinib. The potential for synergy between IBR2 and more drugs was examined in vitro across a spectrum of cancer cell lines from various tissues. Cells were exposed to IBR2 simultaneously with inhibitors of receptor tyrosine kinases, DNA-damaging agents, or microtubule disruptors. IBR2, at concentrations that inhibited proliferation between 0% and 75%, enhanced toxicity by up to 80% of imatinib and regorafenib (targets RAF and kit); epidermal growth factor receptor inhibitors erlotinib, gefitinib, afatinib, and osimertinib; and vincristine, an inhibitor of microtubule function. However, IBR2 antagonized the action of olaparib, cisplatin, melphalan, and irinotecan. A vincristine-resistant squamous cell line was not cross resistant to imatinib, but IBR2 and another RAD51 inhibitor (B02) enhanced imatinib toxicity in this cell line, its HN-5a parent, and the colon cancer line HT-29 by up to 60% and much better than verapamil, a P-glycoprotein inhibitor (P < 0.05). Given the disparate agents the functions of which are enhanced by IBR2, the mechanisms of enhancement may be multimodal. Whether RAD51 is common to these mechanisms remains to be elucidated, but it provides the potential for selectivity to tumor cells.

Phase II trial of capecitabine plus erlotinib versus capecitabine alone in patients with advanced colorectal cancer.

Aim & methods: Capecitabine monotherapy as palliation for advanced colorectal cancer (CRC) is generally well tolerated. Adding erlotinib, an EGFR-tyrosine kinase inhibitor, might improve efficacy versus capecitabine alone. 82 patients received capecitabine alone (Arm 1) or capecitabine with erlotinib (Arm 2). RESULTS: Median time-to-progression (TTP) in Arm 1 was 7.9 months versus 9.2 in Arm 2. In KRAS-wild type (WT) patients TTP was 8.4 and 11.7 months in Arms 1 and 2, respectively. In KRAS-mutated patients TTP was 7.4 and 1.9 months in Arms 1 and 2, respectively (p = 0.023). Arm 2 KRAS-WT patients, left-sided primaries, had an overall survival of 16.0 versus 12.1 months in right-sided primaries. CONCLUSION: Adding erlotinib to capecitabine increased TTP by 3.2 months in KRAS-WT patients. This study suggests that erlotinib harms patients with KRAS-mutated advanced CRC while it may provide benefit to those with KRAS-WT CRC. Further study of EGFR-tyrosine kinase inhibitors in patients with left-sided KRAS-WT CRC is warranted.

Targeting cancer's weaknesses (not its strengths): Therapeutic strategies suggested by the atavistic model.

In the atavistic model of cancer progression, tumor cell dedifferentiation is interpreted as a reversion to phylogenetically earlier capabilities. The more recently evolved capabilities are compromised first during cancer progression. This suggests a therapeutic strategy for targeting cancer: design challenges to cancer that can only be met by the recently evolved capabilities no longer functional in cancer cells. We describe several examples of this target-the-weakness strategy. Our most detailed example involves the immune system. The absence of adaptive immunity in immunosuppressed tumor environments is an irreversible weakness of cancer that can be exploited by creating a challenge that only the presence of adaptive immunity can meet. This leaves tumor cells more vulnerable than healthy tissue to pathogenic attack. Such a target-the-weakness therapeutic strategy has broad applications, and contrasts with current therapies that target the main strength of cancer: cell proliferation.

Real-World Analysis of Durvalumab after Chemoradiation in Stage III Non-Small-Cell Lung Cancer.

The 2017 PACIFIC trial heralded the incorporation of routine adjuvant durvalumab following curative-intent chemoradiation for stage III non-small-cell lung cancer (NSCLC). However, carefully selected clinical trial populations can differ significantly from real-world populations, which can have implications on treatment toxicities and outcomes, making it difficult to accurately counsel patients. Consequently, we performed a real-world, retrospective analysis of outcomes and toxicities in 118 patients with stage III NSCLC treated with durvalumab after platinum-based chemoradiotherapy. The data were collected from patients who underwent treatment at a single, tertiary-level Canadian cancer centre from May 2018 to October 2020. The variables collected included patient demographics, treatment specifics, progression-free survival, overall survival, and immune-related adverse events (IRAE) from durvalumab. Descriptive statistics were used for toxicity analysis, and progression-free survival and overall survival estimates were calculated using the Kaplan-Meier method. The statistical analyses indicated a 64.4% (n = 76) toxicity rate, with a 21% (n = 25) toxicity rate of grade 3+ IRAEs. The most common documented IRAEs were pneumonitis (n = 44; 40%), followed by rash (n = 20; 18%) and thyroid dysfunction (n = 17; 15%). FEV1 and DLCO were not found to be associated predictors of pneumonitis toxicity. The median PFS and OS were estimated to be >1.7 years and >2.7 years, respectively.

Exploitation of treatment induced tumor lysis to enhance the sensitivity of ctDNA analysis: A first-in-human pilot study.

INTRODUCTION: Blood-based liquid biopsies examining circulating tumour DNA (ctDNA) have increasing applications in non-small cell lung cancer (NSCLC). Limitations in sensitivity remain a barrier to ctDNA replacing tissue-based testing. We hypothesized that testing immediately after starting treatment would yield an increased abundance of ctDNA in plasma because of tumor lysis, allowing for the detection of genetic alterations that were occult in baseline testing. METHODS: Three prospective cohorts of patients with stage III/IV NSCLC were enrolled. Cohort 1 (C1) contained patients starting platinum doublet chemoradiation (n = 10) and cohort 2 (C2) initiating platinum doublet cytotoxic chemotherapy ± immunotherapy (n = 10). Cohort 3 (C3) contained patients receiving palliative radiation. Two baseline samples were collected. In C1 and C2, subsequent samples were collected 3, 6, 24 and 48 h post initiation of chemotherapy. Patients in C3 had samples collected immediately prior to the next three radiotherapy fractions. Samples were analyzed for ctDNA using the 36-gene amplicon-based NGS Inivata InVisionFirst®-Lung assay. RESULTS: A total of 40 patients were enrolled. Detectable ctDNA was present at baseline in 32 patients (80%), 4 additional patients (50%) had detectable ctDNA in post-treatment samples. Seven patients with detectable ctDNA at baseline (23%) had new genetic alterations detected in post-treatment samples. Mutant molecule numbers increased with treatment in 24 of 31 (77%) pts with detectable ctDNA. ctDNA levels peaked a median of 7 h (IQR:2-26 h) after the initiation of chemotherapy and a median of 2 days (IQR:1-3 days) after radiation was commenced. CONCLUSION: ctDNA levels increase in the hours to days after starting treatment. ctDNA testing in the acute post-treatment phase can yield results that were not evident in pre-treatment testing. Application of this principle could improve ctDNA utility as an alternate to tissue-based testing and improve sensitivity for the detection of treatment-resistant clones.(NCT03986463).

The quality of life in neoadjuvant versus adjuvant therapy of esophageal cancer treatment trial (QUINTETT): Randomized parallel clinical superiority trial.

BACKGROUND: We compared the health-related quality of life (HRQOL) in patients undergoing trimodality therapy for resectable stage I-III esophageal cancer. METHODS: A total of 96 patients were randomized to standard neoadjuvant cisplatin and 5-fluorouracil chemotherapy plus radiotherapy (neoadjuvant) followed by surgical resection or adjuvant cisplatin, 5-fluorouracil, and epirubicin chemotherapy with concurrent extended volume radiotherapy (adjuvant) following surgical resection. RESULTS: There was no significant difference in the functional assessment of cancer therapy-esophageal (FACT-E) total scores between arms at 1 year (p = 0.759) with 36% versus 41% (neoadjuvant vs. adjuvant), respectively, showing an increase of ≥15 points compared to pre-treatment (p = 0.638). The HRQOL was significantly inferior at 2 months in the neoadjuvant arm for FACT-E, European Organization for Research and Treatment of Cancer quality of life questionnaire (EORTC QLQ-OG25), and EuroQol 5-D-3 L in the dysphagia, reflux, pain, taste, and coughing domains (p < 0.05). Half of patients were able to complete the prescribed neoadjuvant arm chemotherapy without modification compared to only 14% in the adjuvant arm (p < 0.001). Chemotherapy related adverse events of grade ≥2 occurred significantly more frequently in the neoadjuvant arm (100% vs. 69%, p < 0.001). Surgery related adverse events of grade ≥2 were similar in both arms (72% vs. 86%, p = 0.107). There were no 30-day mortalities and 2% vs. 10% 90-day mortalities (p = 0.204). There were no significant differences in either overall survival (OS) (5-year: 35% vs. 32%, p = 0.409) or disease-free survival (DFS) (5-year: 31% vs. 30%, p = 0.710). CONCLUSION: Trimodality therapy is challenging for patients with resectable esophageal cancer regardless of whether it is given before or after surgery. Newer and less toxic protocols are needed.

Functional Lung Avoidance for Individualized Radiation Therapy: Results of a Double-Masked, Randomized Controlled Trial.

PURPOSE: To determine whether functional lung avoidance based on 3He magnetic resonance imaging (MRI) improves quality of life (QOL) for patients undergoing concurrent chemoradiotherapy (CCRT) for advanced non-small cell lung cancer. METHODS AND MATERIALS: Patients with stage III non-small cell lung cancer (or oligometastatic disease treated with curative intent) undergoing CCRT with at least a 10 pack-year smoking history were eligible. Patients underwent pretreatment 3He MRI to measure lung ventilation and had 2 radiation therapy (RT) plans created before randomization: a standard plan, which did not make use of the 3He MRI, and an avoidance plan, preferentially sparing well-ventilated lung. All participants were masked to assignment except the physicist responsible for exporting the selected plan. The primary end point was patient-reported QOL measured at 3-months post-RT by the FACT-L lung cancer subscale (LCS); secondary end points included other QOL metrics, toxicity, and survival outcomes. Target accrual was 64. RESULTS: Twenty-seven patients were randomized before the trial was closed due to slower-than-expected accrual, with 11 randomized to the standard arm and 16 to the avoidance arm. Baseline patient characteristics were well-balanced. At 3 months post-RT, the mean ± SD LCS scores were 17.4 ± 2.8 versus 17.3 ± 6.1 for the standard and avoidance arms, respectively (P = .485). A clinically meaningful, prespecified decline of ≥3 points in the LCS score was observed in 50% (4/8) in the standard arm and 33% (4/12) in the avoidance arm (P = .648). Two patients in each arm developed grade ≥2 radiation pneumonitis, with no grade ≥4 toxicities. CONCLUSIONS: Although this trial did not reach full accrual, QOL scores were very similar between arms. Due to the scarcity of 3He MRI, other, more commonly available methods to measure functional lung, such as 4-dimensional computed tomography ventilation mapping, may be considered in the assessment of functional lung avoidance RT, and a larger, multicenter approach would be needed to accrue sufficient patients to test such approaches.

Skin Deep: A Fascinating Case Report of Immunotherapy-Triggered, Treatment-Refractory Autoimmune Lichen Planus and Keratoacanthoma.

This case discusses a 62-year-old woman with de novo metastatic lung adenocarcinoma (PD-L1 >50% with a KRAS G12C mutation, ALK and EGFR negative) who was on pembrolizumab for 1 year without any significant toxicity, only low-grade dermatitis and hypothyroidism. She was transitioned to pembrolizumab every 6 weeks at 4 mg/kg and began to develop oral sores shortly thereafter. The sores proved refractory to nystatin and mouth rinses containing corticosteroids, and the patient was ultimately diagnosed with autoimmune-triggered lichen planus. Unfortunately, her symptoms also proved refractory to typical treatments for lichen planus and worsened to the point where she began to develop cutaneous lesions and difficulty swallowing. Unfortunately, she also developed a keratoacanthoma that required excision. The pembrolizumab was stopped, and the patient's symptoms improved with 5 days of systemic prednisone, metronidazole, and triamcinolone oral paste. Her NSCLC remains stable off active treatment for 6 months. This case study is on rare auto-immune toxicity as well as a keratoacanthoma from anti-PD-(L) 1 blockade, accompanied by sustained treatment response after cessation of the offending drug.

The price function of toxicity.

The high and accelerating price of new anticancer drugs is giving rise to increased concern. However, monetary price is not the only way to value chemotherapy. Toxic effects can also be seen as a form of payment in which "units" of wellbeing are exchanged for "units" of efficacy. Although this trading analogy is not perfect, a proposal can be made that toxicity is a type of price, and that one of its functions is to signal valuation, similar to the crucial signalling function of monetary price in the real economy. This price function of toxicity, to the extent where there is transparency about the real amounts of toxicity, can have two important and helpful consequences: acting as a brake on the increasing monetary price of new drugs, via a damping effect on demand; and assisting individual patients in the informed contemplation of chemotherapy decisions. However, there are two problems that currently impede the effective dissemination of this highly desirable toxicity information. First, a prediction of toxicity in individual patients is difficult. Second, the vast database of real toxic effects in community practice is rarely made available for public scrutiny. Both of these problems, which together constitute a form of hidden cost, are potentially resolvable at least to some extent. In the absence of accurate information on toxic effects, it is easy for monetary price to progressively diverge from true value. We believe that improved transparency with respect to toxic effects, and better toxicity prediction, offer a better and more genuinely market-orientated solution to the issue of price distortions than the bureaucratic imposition of price controls.

Predictors of Survival Benefit From Immune Checkpoint Inhibitors in Patients With Advanced Non-small-cell Lung Cancer: A Systematic Review and Meta-analysis.

Randomized trials showed inconsistent survival benefit with immune checkpoint inhibitors (ICIs) in patients with advanced non-small-cell lung cancer with low programmed death-ligand 1 (PD-L1) tumors (< 1%) and in elderly patients (> 65 years old) and never-smokers. We conducted a systematic review and meta-analysis to assess the efficacy of single agent ICIs in these pre-defined subgroups. The electronic databases PubMed and EMBASE were searched for relevant randomized trials. Pooled hazard ratios (HRs) for overall survival (OS) and progression-free survival (PFS) were meta-analyzed using the generic inverse variance method. Nine studies were included. Compared with chemotherapy, the use of single agent ICIs in the second-line setting reduced the risk of death independent of PD-L1 expression (HR, 0.79; 95% confidence interval [CI], 0.66-0.96 and HR, 0.75; 95% CI, 0.61-0.85 for patients with PD-L1-negative and -positive tumors, respectively). Yet, a PFS benefit was only seen in patients with PD-L1-positive tumors. Similarly, an OS benefit was seen in patients independent of age (HR, 0.79; 95% CI, 0.69-0.89 and HR, 0.76; 95% CI, 0.66-0.88 for elderly and non-elderly patients, respectively). Conversely, an OS benefit was only seen in ever-smokers (HR, 0.78; 95% CI, 0.68-0.89) and a detrimental effect on PFS in never-smokers (HR, 1.68; 95% CI, 1.07-2.63). Patients with advanced non-small-cell lung cancer derive a survival benefit from ICIs independent of tumor PD-L1 expression and age, particularly in the second line, whereas never-smokers do not. Caution should be exercised when offering single-agent ICIs to elderly patients in the first line, and other treatment options should be considered in never-smokers.

ODN 491, a novel antisense oligodeoxynucleotide that targets thymidylate synthase, exerts cell-specific effects in human tumor cell lines.

Thymidylate synthase (TS) is essential for DNA replication and is a target for cancer chemotherapy. However, toxicity to normal cells and tumor cell drug resistance necessitate development of new therapeutic strategies. One such strategy is to use antisense (AS) technology to reduce TS mRNA and protein levels in treated cells. We have developed oligodeoxynucleotides (ODNs) that target different regions of TS mRNA, inhibit human tumor cell proliferation as single agents, and enhance cytotoxicity of clinically useful TS protein-targeting drugs. Here we describe ODN 491, a novel 20mer AS ODN complementary to a previously untargeted portion of the TS mRNA coding region. AS ODN 491 decreased TS mRNA levels to different degrees in a panel of human tumor-derived cell lines, and induced different physiological effects in a tumor cell line-dependent manner. ODN 491 (like AS TS ODN 83, previously shown to be effective) decreased TS protein levels in HeLa cells with a concomitant increase in sensitivity to TS-targeting chemotherapeutics. However (and contrary to HeLa cell response to an AS ODN 83), it did not, as a single agent, inhibit HeLa cell proliferation. In MCF-7 cells, ODN 491 treatment was less effective at reducing TS mRNA and did not reduce TS protein, nor did it enhance sensitivity to TS-targeting or other chemotherapeutics. Moreover, specifically in MCF-7 cells but not HeLa cells, ODN 491 as a single agent induced apoptosis. These data indicate that AS TS ODN 491 is an effective AS reagent targeting a novel TS mRNA region. However, treatment of tumor cell lines with AS TS ODNs targeting different TS mRNA regions results in a pattern of physiological effects that varies in a tumor cell line-specific fashion. In addition, the capacity of different AS TS ODNs to induce physiological effects does not correlate well with their capacity to reduce TS mRNA and/or protein and, further, depends on the region of TS mRNA selected for targeting. Recognition of tumor cell-specific and mRNA region-specific variability in response to AS TS ODNs will be important in designing AS TS ODNs for potential clinical use.

Cost effectiveness vs. affordability in the age of immuno-oncology cancer drugs.

INTRODUCTION: After years of setback, cancer immunotherapy has begun to yield clinical dividends, which are changing the treatment landscape and offering cancer patients the potential for long-term survival, reduced treatment-related toxicity and improved quality-of-life. Using the immune system to treat cancer is known as 'Immuno-oncology' (IO) and agents are sub-classified by their ability to enhance anti-tumor response or to direct the immune system to attack cancer cells via tumor-associated antigens. Areas covered: Clinical trials have demonstrated the effectiveness of several IO agents in many disease sites such as early and advanced stage melanoma, advanced non-small cell lung cancer, bladder, head and neck, gastric, kidney as well as Hodgkin's lymphoma. Notwithstanding the therapeutic excitement generated for patients and clinicians alike, an important consideration is treatment cost, which can reach more than $US100,000 per patient annually. The cost of the drugs, coupled with high disease prevalence and the ever-expanding number of indications, means the current cost trajectory is untenable for most healthcare systems to sustain. Expert commentary: In this paper, the approved IO drugs and those in clinical development are reviewed. The issue of cost effectiveness vs. affordability is then addressed and suggestions that facilitate patient access and long-term sustainability are presented.

Antisense targeting of thymidylate synthase (TS) mRNA increases TS gene transcription and TS protein: effects on human tumor cell sensitivity to TS enzyme-inhibiting drugs.

Thymidylate synthase (TS) catalyses the only de novo pathway to produce thymidylate for DNA replication and repair and is an important target for cancer chemotherapy. Preexisting or acquired drug resistance in tumor cells limits clinical efficacy of TS-targeting drugs. Cells selected for higher TS protein activity have decreased sensitivity to TS-targeting chemotherapeutic agents (5-FUdR and raltitrexed). New therapeutic strategies are required to overcome treatment resistance. Among these, upregulation of drug resistance mediators in normal, nontarget cells and/or antisense downregulation of those mediators (alone or in combination with protein-targeting drugs) are candidate strategies. We have targeted human TS mRNA with antisense oligodeoxynucleotides (AS ODNs), complementary to the translation start site (TSS), the coding region, and the 3' untranslated region. We report here that, in response to treatment with a novel TSS-targeting AS ODN 791, TS gene transcription in a human cervical carcinoma cell line (HeLa) was unexpectedly increased by 70%. Interestingly, the increased TS gene transcription and nuclear TS RNA did not elevate levels of total cellular TS mRNA, but did increase TS protein activity by 35% and TS protein level by 150%. Increased TS protein activity and level did not alter proliferation rate or sensitivity to TS-targeting drugs (5-FUdR or raltitrexed). To assess concentration-dependent effects of TS on sensitivity to TS-targeting drugs, incremental increases of TS protein levels were generated by transfection of a mammalian TS expression vector. Increases in TS protein of less than approximately 400% did not significantly affect sensitivity to TS-targeting drugs, while greater TS protein levels did. These data indicate that AS ODNs targeting TS mRNA can upregulate TS expression and activity in a manner dependent on the sequence being targeted, and that there exists a threshold increase (greater than approximately 400-700% in HeLa cells), required to initiate resistance to TS-targeting drugs.

Therapeutic potential of antisense oligodeoxynucleotides to down-regulate thymidylate synthase in mesothelioma.

Malignant mesothelioma is an aggressive tumor of the serosal surfaces of the lungs, heart, and abdomen. Survival rates are poor and effective treatments are not available. However, recent therapeutic regimens targeting thymidylate synthase (TS) in malignant mesothelioma patients have shown promise. We have reported the use of an antisense oligodeoxynucleotide targeting TS mRNA (antisense TS ODN 83) to inhibit growth of human tumor cells. To test the potential for antisense targeting of TS mRNA in treatment of malignant mesothelioma, we assessed and compared the effects of antisense TS ODN 83 on three human malignant mesothelioma cell lines (211H, H2052, and H28) and human nonmalignant mesothelioma cells (HT29 colorectal adenocarcinoma, HeLa cervical carcinoma, and MCF7 breast tumor cell lines). We report that ODN 83 applied as a single agent effectively reduced TS mRNA and protein in malignant mesothelioma cell lines. Furthermore, it inhibited malignant mesothelioma growth significantly more effectively than it inhibited growth of nonmalignant mesothelioma human tumor cell lines: a difference in susceptibility was not observed in response to treatment with TS protein-targeting drugs. In malignant mesothelioma cells, antisense TS both induced apoptotic cell death and reduced proliferation. In nonmalignant mesothelioma cells, only reduced proliferation was observed. Thus, antisense TS-mediated induction of apoptosis may be the basis for the high malignant mesothelioma sensitivity to antisense targeting of TS. Further preclinical and clinical study of TS antisense oligodeoxynucleotides, alone and in combination with TS-targeting chemotherapy drugs, in mesothelioma is warranted.

Pretreatment Serum Folate Levels and Toxicity/Efficacy in Colorectal Cancer Patients Treated With 5-Fluorouracil and Folinic Acid.

BACKGROUND: 5-Fluorouracil (5-FU) chemotherapy is associated with severe and unpredictable toxicity in a significant proportion of patients. 5,10-Methylenetetrahydrofolate and 5-fluorodeoxyuridine monophosphate bind to thymidylate synthase and together inhibit its function, resulting in cytotoxicity. We hypothesized that susceptibility to 5-FU toxicity might be related to individual differences in the serum components of folate metabolism affecting intracellular 5,10-methylenetetrahydrofolate levels. PATIENTS AND METHODS: A prospective cohort of chemotherapy-naive colorectal cancer patients scheduled to receive intravenous 5-FU and folinic acid for 5 consecutive days every 4 weeks in both adjuvant and palliative settings was studied. Pretreatment clinical and laboratory data were collected. Biochemical data associated with folate metabolism were also collected. The primary endpoint was the occurrence of grade ≥ 3 toxicity and/or toxicity mandating dose delay or reduction. RESULTS: For the 78 eligible patients studied, multivariable analyses identified only a greater pretreatment serum folate level as an independent predictor of grade ≥ 3 toxicity and/or mandating schedule modification (P = .016). Comparing the patient cohorts among the folate quartile groups revealed increasing toxicity trends in the highest quartile with an odds ratio of 2.58 (P = .19) compared with the combined lower quartiles, and superior relapse-free and overall survival for patients treated in the adjuvant setting. Log-rank analysis showed a significant association between higher folate levels and relapse-free and overall survival. CONCLUSION: The pretreatment serum folate level did not conclusively influence 5-FU toxicity and antitumor efficacy. However, high folate levels showed a trend toward a greater incidence of severe toxicities but also lower rates of disease recurrence and mortality. These results provide promising hypothesis-generating data warranting further investigation. The predictive value of pretreatment folate status should be a priority for study in cancer patients receiving 5-FU-based chemotherapy and should be considered a potentially confounding factor in clinical trials and a modifiable parameter in treatment.

Continued cigarette smoking by patients receiving concurrent chemoradiotherapy for limited-stage small-cell lung cancer is associated with decreased survival.

PURPOSE: To determine the impact of continued smoking by patients receiving chemotherapy (CHT) and radiotherapy (RT) for limited-stage small-cell lung cancer (LSCLC) on toxicity and survival. PATIENTS AND METHODS: A retrospective review was carried out on 215 patients with LSCLC treated between 1989 and 1999. Treatment consisted of six cycles of alternating cyclophosphamide, doxorubicin, vincristine and etoposide, cisplatin (EP). Thoracic RT was concurrent with EP (cycle 2 or 3) only. Patients were known smokers, with their smoking status recorded at the start of chemoradiotherapy (CHT/RT). RT interruption during concurrent CHT/RT was used as the marker for treatment toxicity. RESULTS: Of 215 patients, smoking status was recorded for 186 patients (86.5%), with 79 (42%) continuing to smoke and 107 (58%) abstaining during CHT/RT. RT interruptions were recorded in 38 patients (20.5%), with a median duration of 5 days (range, 1 to 18 days). Median survival for former smokers was greater than for continuing smokers (18 v 13.6 months), with 5-year actuarial overall survival of 8.9% versus 4%, respectively (log-rank P =.0017). Proportion of noncancer deaths was comparable between the two cohorts. Continuing smokers did not have a greater incidence of toxicity-related treatment breaks (P =.49), but those who continued to smoke and also experienced a treatment break had the poorest overall survival (median, 13.4 months; log-rank P =.0014). CONCLUSION: LSCLC patients who continue to smoke during CHT/RT have poorer survival rates than those who do not. Smoking did not have an impact on the rate of treatment interruptions attributed to toxicity.

Multicenter phase III study of uracil/tegafur and oral leucovorin versus fluorouracil and leucovorin in patients with previously untreated metastatic colorectal cancer.

PURPOSE: This phase III study was designed to demonstrate equivalence in survival of oral uracil/tegafur (UFT) and oral leucovorin (LV) to conventional intravenous (IV) fluorouracil (5-FU) and LV in previously untreated metastatic colorectal carcinoma. Safety was also compared. PATIENTS AND METHODS: Eight hundred sixteen patients were randomized to receive either UFT (300 mg/m(2)/d) and LV (75 or 90 mg/d) for 28 days every 35 days or IV bolus 5-FU (425 mg/m(2)/d) and LV (20 mg/m(2)/d) for 5 days every 28 days. RESULTS: UFT/LV produced survival comparable to the IV 5-FU/LV regimen. Median survival was 12.4 months (95% confidence interval [CI], 11.2 to 13.6 months) with UFT/LV and 13.4 months (95% CI, 11.6 to 15.4 months) with 5-FU/LV (P =.630). The hazard ratio for survival was 0.964 (95.6% CI, 0.826 to 1.125), supporting equivalent survival. The overall response rate did not differ between treatment arms (UFT/LV, 11.7%; 5-FU/LV, 14.5%; P =.232). Median time to progression favored 5-FU/LV (UFT/LV, 3.5 months; 5-FU/LV, 3.8 months; P =.011), but tumor assessment schedules differed between arms. UFT/LV significantly improved safety compared with 5-FU/LV. Diarrhea, nausea and vomiting, and stomatitis and mucositis were significantly less frequent with UFT/LV, as was myelosuppression. Patients treated with UFT/LV had fewer episodes of febrile neutropenia (P <.001) and documented infections (P <.05). Increased bilirubin, without other liver function abnormalities, was observed more often with UFT/LV (P <.001). Concomitant medications were more frequent with 5-FU/LV, including use of antibiotics, growth factors, and antiemetics. CONCLUSION: UFT/LV provided a safer, more convenient oral alternative to a standard bolus IV 5-FU/LV regimen for metastatic colorectal cancer while producing equivalent survival.