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.

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.

Abstract 346: Synergistic antiproliferative activity of novel RAD51 inhibitor JKYN-1 and its mesylate salt with standard-of-care cancer drugs

The inherent genetic instability of cancer cells and the dependence of many tumor types on oncogenic drivers contribute selectivity of anticancer agents against tumor cells. That selectivity is limited, and toxicity to normal cells remains a major limitation to the success of chemotherapy. To increase selectivity by exploiting cancer cell genetic instability, we demonstrated that the small molecule IBR2 (an inhibitor of the DNA repair protein RAD51) enhanced cytotoxicity of numerous anticancer drugs including agents that do not directly target DNA (J Pharmacol Expt Ther, 364: 46-54, 2018. doi.org/10.1124/jpet.117.241661). We demonstrated the ability of IBR2 and a derivative [IBR120, (R)-3-(2-(benzylsulfonyl)isoindolin-1-yl)-1h-indole] to synergistically inhibit proliferation of a wider range of cancer cell lines in combination with a broad range of anticancer drugs (Proc. Amer. Assoc. Cancer Res., 60: Abst. 3057, 2019). To improve the activity and potentially increase selectivity for inhibiting RAD51, modifications were made to the structure of IBR120 using a virtual drug-protein docking program, yielding the compound JKYN-1. JKYN-1 inhibits proliferation of cancer cell lines approximately 5 times more strongly than IBR120. Given the potential importance of combining JKYN-1 with targeted anticancer drugs to increase therapeutic index, and the synergy previously observed between IBR120 and agents targeted against specific tumor types, JKYN-1 was tested in combination with targeted agents against a panel of tumor cell lines. Four- to five-day drug exposures were conducted in 96-well plates. Relative cell density determined using vital stains (alamarBlue©, neutral red) was reported as a percent of the fluorescence/absorbance of control cultures. Cell lines were representative of tumors from breast (MCF-7), prostate (DU145, LNCaP), stomach (N87), pancreas (PANC-1, Capan-1, Capan-2) and lung (A549b, H1650). The chemotherapy agents included inhibitors of epidermal growth factor receptor (osimertinib, afatinib), other tyrosine kinases (regorafenib, imatinib), sex steroid receptors (4-OH-tamoxifen, enzalutamide), and microtubule function (docetaxel). To improve solubility, a methylsulfonate salt of JKYN-1 was used for most experiments. JKYN-1-mesylate decreased the concentration of drugs that inhibited proliferation by 50% (IC50) by up to 90%, depending on the drug and cell line, indicating synergy between the agents. There were some combinations in which additivity but no synergy was observed, indicating selectivity for this interaction. Individual combinations will be presented. The ability of JKYN-1 to enhance antiproliferative activity of a wide variety of anticancer agents, and its potential selectivity for cancer cells, make possible the future use of RAD51 inhibitors as systemic therapy potentiators to improve clinical outcomes.

Citation Format: Peter J. Ferguson, Mark D. Vincent, Yousef Najajreh, Brian Shilton, Stephen Ritter, Rima Al-awar, Richard Marcellus, Mohammed Mohammed, Methvin Isaac, James Koropatnick. Synergistic antiproliferative activity of novel RAD51 inhibitor JKYN-1 and its mesylate salt with standard-of-care cancer drugs [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 346.

Abstract 1062: Antiproliferative activity of EC359, an inhibitor of leukemia inhibitory factor receptor (LIF-R), singly and in combination with chemotherapy drugs against pancreatic cancer cell lines

Although combination chemotherapy treatments such as FOLFIRINOX (5-fluorouracil, oxaliplatin, irinotecan), gem-abraxane (gemcitabine and nab-paclitaxel) and GTX (gemcitabine, docetaxel and capecitabine) have improved survival of pancreatic cancer patients incrementally, 5-year-survival for this disease remains dismal. New and more effective treatments are needed. Pancreatic stellate cells (PSCs), a form of fibroblasts that comprise much of the pancreatic tumor microenvironment, interact with the cancer cells via the cytokine leukemia inhibitory factor (LIF) and its receptor, LIF-R. This interaction contributes to tumor progression, survival, and resistance to various therapies, and is an important target for novel therapy. A small molecule inhibitor of LIF-R, EC359, inhibits growth of breast cancer cell line tumor explants in mice (Mol Cancer Ther 18: 1341-1354, 2019) and potentially modulates the activity of gemcitabine against such explants (Genes Cancer 10: 1-10, 2019). Given the involvement of the LIF axis in pancreatic cancer, EC359 was tested for its ability to inhibit proliferation of the human pancreatic cancer cell lines PANC-1, Capan-1, and Capan-2, and its possible influence on activity of chemotherapy drugs against these cell lines. Five-day drug exposures were conducted in 96-well plates. Relative cell density determined using vital stains (alamarBlue©, neutral red) was reported as a percent of the fluorescence/absorbance of control cultures. The 3 cell lines exhibited different sensitivities to EC359, with IC50 values ranging from 5 nM (Capan-1) to 150 nM (Capan-2). When combined with anti-pancreatic cancer standard-of-care drugs, EC359 yielded synergistic interactions in a concentration-dependent manner. Depending on the cell line, EC359 decreased the IC50 value for oxaliplatin by as much as 83%. Such enhancements of cytotoxicity for other drugs were up to 84% for docetaxel, 67% for paclitaxel, and 50% for irinotecan. EC359 was also synergistic with IBR120 (a novel small molecule inhibitor of RAD51) against PANC-1 cells. EC359 additively inhibited proliferation in combination with irinotecan or 5-FUdR. The nanomolar activity of EC359 against pancreatic cancer cell lines makes it a good candidate for potential treatment of this generally refractory disease. The synergistic interaction of EC359 with standard-of-care drugs provides an opportunity for increasing the therapeutic index for these agents, and ultimately improving clinical outcomes for pancreatic cancer and other cancers against which EC359 is currently in clinical trial.

Citation Format: Peter J. Ferguson, Hareesh Nair, Mark D. Vincent, James Koropatnick. Antiproliferative activity of EC359, an inhibitor of leukemia inhibitory factor receptor (LIF-R), singly and in combination with chemotherapy drugs against pancreatic cancer cell lines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1062.

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.

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).

Abstract PO-039: Antiproliferative activity of inhibitors of RAD51, singly and in combination with chemotherapy drugs, against pancreatic cancer cell lines

Despite the innovations in chemotherapeutic treatment of pancreatic cancer, the generally poor outcome of this disease begs the search for novel targets. RAD51 is a critical component of homologous recombination DNA repair, binding with BRCA2 and forming polymeric filaments essential for its function. RAD51 is often elevated in cancer cells compared to normal cells, particularly in pancreatic cancer: RAD51 is a negative prognostic biomarker and promotes tumor cell proliferation in that disease (Cancer Cell Int 19: 356, 2019; doi: 10.1186/s12935-019-1077-6). Therefore, RAD51 is an attractive target for anticancer treatment in that its elevated level and activity in tumor cells provide a potential level of selectivity for such an agent, increasing the therapeutic index. We demonstrated previously that novel inhibitors of RAD51, IBR2 [2-(Benzylsulfonyl)-1-(1H-indol-3-yl)-1,2-dihydroisoquinoline] and IBR120 (an isoindolinyl derivative of IBR2) (Eur J Med Chem. 96:196-208, 2015; doi: 10.1016/j.ejmech.2015.04.021), not only inhibited proliferation of a range of tumor cell lines at micromolar concentrations but also acted in combination with commonly used cytotoxic chemotherapy and molecularly targeted drugs to synergistically inhibit proliferation (J Pharmacol Expt Ther, 364: 46-54, 2018; doi.org/10.1124/jpet.117.241661). To improve ADME properties, enhance activity, and increase potential to selectively target RAD51, advanced computational tools and rational approaches were employed to predict possible modification to the IBR chemical backbone. This effort resulted in discovery of the compound JKYN-1. As a model system in which to test the activity of JKYN-1 in vitro, human pancreatic cancer cell lines PANC-1, Capan-1 and Capan-2 were used. All lines have mutant K-Ras and p53, and Capan-1 has mutant BRCA2 (https://www.cancer.gov/research/key-initiatives/ras; https://web.expasy.org/cellosaurus). JKYN-1 or its water-soluble methylsulfonate salt (JKYN-1-mesylate) inhibit proliferation of PANC-1 cells approximately 5 times more effectively than IBR120 and inhibit Capan-1 and Capan-2 cells even better. Against PANC-1, JKYN-1-mesylate inhibits proliferation synergistically in combination with afatinib (inhibitor of epidermal growth factor receptor) or with IBR120, and is additive with gemcitabine. Biochemical characterization of the interaction between RAD51 and these inhibitors demonstrated the following: (1) IBR2 and IBR120 promote disassembly of RAD51 multimers in an ex vivo native polyacrylamide gel electrophoresis assay using clonal constructs of RAD51, and (2) JKYN-1 binds to RAD51 with higher affinity than IBR120 and B02, a commercially available RAD51 inhibitor, in a surface plasmon resonance spectroscopy assay. Therefore, JKYN-1 is a potential novel small molecule therapeutic agent for treatment of pancreatic cancer, both as a single agent and in combination with standard chemotherapy drugs.

Citation Format: Peter Ferguson, Mark D. Vincent, Yousef Najajreh, Brian Shilton, Stephen Ritter, Rima Al-awar, Richard Marcellus, Mohammed Mohammed, Methvin Isaac, James Koropatnnick. Antiproliferative activity of inhibitors of RAD51, singly and in combination with chemotherapy drugs, against pancreatic cancer cell lines [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2021 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2021;81(22 Suppl):Abstract nr PO-039.

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.

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.

Abstract 3057: Synergistic antiproliferative activity between anticancer drugs and RAD51 inhibitors IBR2 and IBR120

The inherent genetic instability of cancer cells and the dependence of many tumor types on oncogenic drivers contribute selectivity of anticancer agents against tumor cells. However, that selectivity is limited, and toxicity to normal cells remains a major limitation to the success of chemotherapy. Aiming to increase selectivity by exploiting cancer cell genetic instability, we demonstrated that the small molecule IBR2 (an inhibitor of the DNA repair protein RAD51) enhanced cytotoxicity of numerous anticancer drugs, including agents that do not directly target DNA (J Pharmacol Expt Ther, 364: 46-54, 2018). Given the potential importance of combining IBR2 with anticancer treatment to increase therapeutic index, IBR2 was tested in combination with other untested agents against a panel of tumor cell lines. In addition, studies were expanded to include IBR120 [(R)-3-(2-(benzylsulfonyl)isoindolin-1-yl)-1h-indole], a new small molecule RAD51 inhibitor that is reportedly more selective against cancer cell lines (Euro J Med Chem 96: 196-208, 2015). Four-day drug exposures were conducted in 96-well plates. Relative cell density, determined using vital stains (alamarBlue©, neutral red), was reported as a percent of the fluorescence/absorbance of control cultures. Cell lines were representative of tumors from breast (MCF-7, SK-BR-3), prostate (LNCaP, DU145), colon (HT-29), stomach (N87), skin (SK-MEL-5), and lung (A549b, H1650, H1975), including osimertinib-resistant derivatives of the non-small-cell lung cancer (NSCLC) cell lines. The chemotherapy agents included inhibitors of epidermal growth factor receptor (EGFR) family (osimertinib, afatinib, lapatinib), Bcr-Abl (imatinib), B-raf (vemurafenib), multiple tyrosine kinases (regorafenib), sex steroid receptors (4-OH-tamoxifen, enzalutamide), and microtubules (vincristine). Both IBR2 and IBR120 decreased the concentration of drugs that inhibited proliferation by 50% (IC50) by up to 90%, indicating synergy between the agents. However, there were a small number of combinations in which no synergy was observed, indicating selectivity for this interaction. In the NSCLC cell lines, IBR2, IBR120, osimertinib, gefitinib, and afatinib decreased the cellular content of RAD51 by over 80% within 24 h (western blot with antibody 3C10), at concentrations at or lower than their IC50 value. The contribution of this decrease in RAD51 to synergy is being investigated. Studies are ongoing to determine the effect of IBR120 on growth of explants of the NSCLC cell line H1650 in mice, after which the combination of IBR120 and osimertinib will be tested in vivo. The ability of IBR2 and IBR120 to enhance antiproliferative activity of a wide variety of anticancer agents and their potential selectivity for cancer cells make possible their future use as systemic therapy potentiators to improve clinical outcomes.

Citation Format: Peter J. Ferguson, Morgan Black, Rene Figueredo, Mark D. Vincent, James Koropatnick. Synergistic antiproliferative activity between anticancer drugs and RAD51 inhibitors IBR2 and IBR120 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3057.

Abstract 1817: Establishment and characterization of non-small cell lung cancer cell line variants selected for resistance to osimertinib

Many non-small cell lung cancers (NSCLC) are oncogenically driven by mutant epidermal growth factor receptor (EGFR). EGFR tyrosine kinase inhibitors (TKIs) are commonly used as a first-line treatment against such tumors, but NSCLC tumors often recur with a mutant EGFR (often with a T790M mutation in exon 20) that confers resistance to these drugs [Ther Adv Respir Dis 10(6): 549-565, 2016]. Third generation EGFR TKIs (e.g., osimertinib) have been designed that are highly active aganst both T790M EGFR and the original non-T790M-mutated, oncogenic EGFR. Clinical resistance to third generation TKIs has been observed, but model systems in which to study the mechanisms of resistance are few. The human NSCLC cell line H1975, derived from an EGFR-TKI-resistant tumor, contains EGFR mutations T790M and L858R (exon 21). To explore mechanisms mediating resistance to third generation TKIs, we selected variants of the H1975 cell line for resistance to osimertinib to create models in which mechanisms of resistance can be characterized and tested for potential methods to overcome that resistance. Cells were exposed continuously to a single concentration of osimertinib, in some cases with the inclusion of verapamil to avoid possible selection of multidrug resistant cells. After 4 weeks, with weekly changes of drug-medium, clonal cell lines were selected in the presence of 6 and 10 μM osimertinib (one each) or in 5 μM osimertinib plus 10 μM verapamil (3 cell lines). These clonal lines were, respectively, 90-, 95-, 38-, 227-, and 244-fold resistant to osimertinib. The RAD51 inhibitor 2-(benzylsulfonyl)-1-(1H-indol-3-yl)-1,2-dihydroisoquinoline (IBR2), which enhances cytotoxicity of several EGFR inhibitors against numerous cell lines (Ferguson et al., JPET 2017, doi.org/10.1124/jpet.117.241661), decreased osimertinib-resistance by up to 80% in these cell lines. Sequence analysis indicates that cell line H1975/osi-6b retained the same EGFR sequence as that in the parent cell line. H1975/osi-5b/VPL appears to have undergone epithelial-to-mesenchymal transition. Further analyses of the resistant cell lines are being undertaken. These cell lines are a valuable resource in which to test methods to circumvent resistance to third generation EGFR TKIs.

Citation Format: Peter J. Ferguson, Mark D. Vincent, James Koropatnick. Establishment and characterization of non-small cell lung cancer cell line variants selected for resistance to osimertinib [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1817.

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.

Phase I study of concurrent and consolidation cisplatin and docetaxel chemotherapy with thoracic radiotherapy in non-small cell lung cancer

Background

We designed a phase i study of concurrent chemoradiotherapy (ccrt) with docetaxel (D) and cisplatin (C), followed by consolidation dc, for unresectable stage iii non-small cell lung cancer (nsclc).

Methods

Patients with histologically proven and unresectable stage iii nsclc were eligible. During ccrt, C was given every 3 weeks (75 mg/m²) and D given weekly. The starting dose of D was 20 mg/m², escalated in cohorts of 3 to define the maximum tolerated dose (mtd). Radiotherapy was prescribed to a dose of 60 Gy in 30 fractions. This was followed by 2 cycles of consolidation dc, which were dose escalated if ccrt was tolerated.

Results

Twenty-six patients were enrolled, with 1 excluded following evidence of metastatic disease. Nineteen patients completed both phases of treatment. There were 7 grade 3 events during ccrt (5 esophagitis, 2 nausea), and 8 grade 3 events during consolidation (2 neutropenia, 2 leukopenia, 1 esophagitis, 2 nausea, and 1 pneumonitis). Three patients had grade 4 neutropenia. No patients died due to toxicities. The mtd of concurrent weekly D was 20 mg/m². Consolidation D and C were each dose escalated to 75 mg/m² in 8 patients. The median overall survival (os) and progression-free survival (pfs) of all patients were 33.6 months and 17.2 months, respectively, with median follow-up of 26.6 months (range 0.43-110.8).

Conclusions

The use of docetaxel 20 mg/m² weekly and cisplatin 75 mg/m² every 3 weeks concurrent with thoracic radiotherapy, followed by consolidation docetaxel and cisplatin, both given at 75 mg/m² every 3 weeks, appears to be safe in this phase i trial.

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 I/II trial of dose-reduced capecitabine in elderly patients with advanced colorectal cancer

BACKGROUND

Combination chemotherapy is associated with improved outcomes in trials of selected fit patients with advanced colorectal cancer (acrc). For older or less-fit patients, combination chemotherapy is associated with greater toxicity and less benefit. Capecitabine monotherapy is a reasonable option for those patients, but the optimal dose remains controversial.

METHODS

A multicentre phase i/ii trial of reduced-dose capecitabine (2000 mg/m², days 1-14 every 21 days) was conducted in 221 patients representing one or more of the following subsets: age greater than 65 years (n = 167), Eastern Cooperative Oncology Group (ecog) performance status of 1 or greater (n = 139), elevated lactate dehydrogenase (ldh) (n = 105), or prior pelvic radiation (n = 54). Based on phase i results, patients with prior pelvic radiation received capecitabine 750 mg/m² twice daily. The goal was to ascertain efficacy in a design that was unlikely to cause high levels of toxicity.

RESULTS

Median age in the patient cohort was 72 years. A median of 5 and a mean of 8 capecitabine cycles were given (range: 0-50 cycles). Grade 3 or 4 toxicity occurred in 25% of patients during the first 3 cycles (8.1% hand-foot syndrome, 7.7% diarrhea). The response rate was 13.6%, with a 69.7% disease control rate. Median progression-free survival (pfs) was 5.6 months. Post progression, 56 patients received further capecitabine monotherapy (median of 4 additional cycles). Median overall survival duration for the patients was 14.3 months. Median survival was significantly higher for those who, at baseline, had an ecog performance status of 0 (compared with 1 or more) and normal ldh (compared with elevated ldh).

CONCLUSIONS

Toxicity is less with dose-reduced capecitabine than with historical full-dose capecitabine, with only a small trade-off in efficacy, seen as a lower objective response rate. The improved tolerability could lead to an increased number of cycles of therapy, and pfs appears to be consistently higher at the lower dose. Those observations should, in the absence of a head-to-head clinical trial, be viewed as compelling evidence that 1000 mg/m², or even 750 mg/m², twice daily is an appropriate dose in elderly or frail patients with acrc.

Abstract 2019: Synergistic anticancer 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 selective toxicity that some chemotherapy drugs have for cancer cells. This "synthetic lethality" (Nature 434:913, ‘05) can be enhanced by agents that inhibit DNA repair (Mol Onc 8:1429, ‘14; Proc AACR 57:3718, ‘16). To exploit this potential "Achilles heel", we tested the ability of a small molecule inhibitor of RAD51 to potentiate the cytotoxicity of established chemotherapy drugs. 2-(benzylsulfonyl)-1-(1H-indol-3-yl)-1,2-dihydroisoquinoline (IBR2) was obtained from Drs. J-W Zhu and W-H Lee (Univ. California - Irvine). IBR2 inhibits RAD51-mediated double-strand DNA break repair, but also enhances induction of apoptosis by the ABL inhibitor imatinib against K562 cells (EMBO Mol Med 5:353, ‘13). There is potential value of such synergistic interaction among other tumor types and with other drugs. IBR2-drug combinations were therefore examined across a spectrum of cancer cell lines from various tissues (AML, CML, carcinoma of breast, colon, stomach, lung, and head) representing a range of oncogenic drivers (ABL, c-kit, Raf, Ras, ER, mutant p53). Cells were exposed to IBR2 simultaneously with inhibitors of various tyrosine kinase receptors, DNA-damaging agents, or inhibitors of microtubule function. Cells were cultured in 96-well plates, exposed to drugs alone and in combination, and cell density determined by viability staining (alamarBlue or neutral red) 4 days later. Inhibition of proliferation by drug combinations was normalized to that of IBR2 alone. Depending on the drug sensitivity of the cell line, IBR2, at concentrations that inhibited proliferation between 0% and 75% as a single agent, enhanced toxicity of imatinib by up to 80%. IBR2 also greatly enhanced antiproliferative activity of regorafenib (targets RAF, kit, others), EGFR inhibitors erlotinib, gefitinib, afatinib and osimertinib, and microtubule inhibitor vincristine (VCR). However, IBR2 was antagonistic with VP-16, cisplatin, irinotecan, melphalan, and olaparib. To determine a possible mechanism of the observed synergy, the interaction between IBR2 and imatinib or VCR was compared with that between verapamil, a P-glycoprotein inhibitor, and the latter 2 drugs. The VCR-resistant head and neck cell line HN-5a/V15e was not cross-resistant to imatinib, but IBR2 enhanced imatinib toxicity in this cell line, its HN-5a parent, and HT-29 by up to 60%, much better than verapamil (up to 40% at similar concentrations, P&lt;0.05). IBR2 enhanced VCR toxicity in these 3 lines to degree similar to verapamil, decreasing the IC50 by up to 90%. IBR2 appears to enhance drug toxicities via mechanisms other than just inhibition of RAD51 and may potentially interfere with microtubule function. The results indicate that this agent may be useful as a clinical adjuvant to numerous cytotoxic drugs.

Citation Format: Peter J. Ferguson, Mark D. Vincent, James Koropatnick. Synergistic anticancer activity of the RAD51 inhibitor IBR2 with inhibitors of receptor tyrosine kinases and microtubule protein [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2019. doi:10.1158/1538-7445.AM2017-2019

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.

Abstract 3718: Sensitization of human tumor cells to chemotherapy drugs by antisense downregulation of RAD51: Targeting DNA repair to induce synthetic lethality

The inherent genomic instability of cancer cells has been exploited as a tumor-selective drug target to treat tumors that are deficient in specific mechanisms of DNA repair. Inhibitors of poly(ADP-ribose) polymerase (PARP) are routinely used clinically against tumors deficient in BRCA1 or BRCA2, due to the poor capacity of these cells to undergo homologous recombination repair (HRR). This exploitation of a tumor cell deficiency to enhance selectivity to a particular drug is “synthetic lethality” (Nature 434: 913, 2005). To make use of this phenomenon in tumors that may not be inherently hypersensitive to a particular treatment, we have sought to induce synthetic lethality by down-regulating essential components of DNA repair, in particular BRCA2, to sensitize cells to chemotherapy drugs [Mol Oncol 8(8): 1429-1440, 2014]. Given that an important function of BRCA2 is to modulate the action of RAD51 in HRR, we determined whether antisense knockdown of RAD51 could enhance tumor cell sensitivity to the PARP inhibitor olaparib and the DNA-crosslinking agent cisplatin. Four different anti-RAD51 siRNA molecules (Dharmacon), targeting coding sequences, were tested against cell lines representative of different tumor types in an in vitro assay of proliferation (non-small cell lung cancer line A549b, colon carcinoma line HT-29, and prostate carcinoma lines DU145 and LNCaP). The siRNAs, as single agents, inhibited proliferation in a concentration-dependent fashion and to varying degrees, and sensitized tumor cells to olaparib. A sequence that targeted region 1169-1187 of the RAD51 cDNA (NM_002875.4) was utilized for further studies. At concentrations of anti-RAD51 siRNA 51a that inhibited proliferation of cell lines by less than 50%, 51a enhanced cytotoxicity of olaparib by over 90% and of cisplatin by 60-90%. In all cell lines except LNCaP (with mutant BRCA2) the combination of siRNAs against RAD51 and BRCA2 acted cooperatively to enhance cytotoxicity of olaparib and cisplatin. Notably, when used together, each siRNA down-regulated expression of its respective target mRNA, as demonstrated by quantitative RT-PCR, without interfering with the activity of the other. RAD51 can be exploited clinically as a target for inherent or induced synthetic lethality to DNA-damaging agents (e.g., cisplatin) or inhibitors of DNA repair (e.g., olaparib). Such treatment can include tumors with BRCA2-deficiency, either inherent or induced, to yield at least an additive anticancer effect. MR is a scholar of the CIHR Strategic Training Program in Cancer Research and Technology Transfer (CaRTT) and a recipient of the CIHR Banting and Best Canada Graduate Scholarship.

Citation Format: Peter J. Ferguson, Mateusz Rytelewski, Mark D. Vincent, James Koropatnick. Sensitization of human tumor cells to chemotherapy drugs by antisense downregulation of RAD51: Targeting DNA repair to induce synthetic lethality. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3718.

siRNA knockdown of mitochondrial thymidine kinase 2 (TK2) sensitizes human tumor cells to gemcitabine

Nucleoside metabolism enzymes are determinants of chemotherapeutic drug activity. The nucleoside salvage enzyme deoxycytidine kinase (dCK) activates gemcitabine (2', 2'-difluoro-2'-deoxycytidine) and is negatively regulated by deoxycytidine triphosphate (dCTP). Reduction of dCTP in tumor cells could, therefore, enhance gemcitabine activity. Mitochondrial thymidine kinase 2 (TK2) phosphorylates deoxycytidine to generate dCTP. We hypothesized that: (1) TK2 modulates human tumor cell sensitivity to gemcitabine, and (2) antisense knockdown of TK2 would decrease dCTP and increase dCK activity and gemcitabine activation. siRNA downregulation of TK2 sensitized MCF7 and HeLa cells (high and moderate TK2) but not A549 cells (low TK2) to gemcitabine. Combined treatment with TK2 siRNA and gemcitabine increased dCK. We also hypothesized that TK2 siRNA-induced drug sensitization results in mitochondrial damage that enhances gemcitabine effectiveness. TK2 siRNA and gemcitabine decreased mitochondrial redox status, DNA content, and activity. This is the first demonstration of a direct role for TK2 in gemcitabine resistance, or any independent role in cancer drug resistance, and further distinguishes TK2 function from that of other dTMP-producing enzymes [cytosolic TK1 and thymidylate synthase (TS)]. siRNA knockdown of TK1 and/or TS did not sensitize cancer cells to gemcitabine indicating that, among the 3 enzymes, only TK2 is a candidate therapeutic target for combination with gemcitabine.

Promising targets and current clinical trials in metastatic squamous cell lung cancer

Squamous cancer of the lung (SQCC), although no longer the premier variant of non-small cell lung cancer, continues to impose a heavy world-wide burden. Advanced SQCC has enjoyed little of the recent progress benefiting patients with adenocarcinoma of the lung, but that has now begun to change. This article reviews the underlying molecular pathology of SQCC, as well as potential new targets and the corresponding novel targeted agents; included are some of which may soon be approvable in this notoriously hard-to-treat indication.

Biomarkers That Currently Affect Clinical Practice in Lung Cancer: EGFR, ALK, MET, ROS-1, and KRAS

Lung cancer remains the most lethal malignancy in the world. Despite improvements in surgical treatment, systemic therapy, and radiotherapy, the 5-year survival rate for all patients diagnosed with lung cancer remains between 15 and 20%. Newer therapeutic strategies rely on specific molecular alterations, or biomarkers, that provide opportunities for a personalized approach to specific patient populations. Classification of lung cancer is becoming increasingly focused on these biomarkers, which renders the term "non-small cell lung" cancer less clinically useful. Non-small cell lung cancer is now recognized as a complex malignancy and its molecular and genomic diversity allows for patient-centered treatment options. Here, we review advances in targeted treatment of lung adenocarcinoma with respect to five clinically relevant biomarkers - EGFR, ALK, MET, ROS-1, and KRAS.

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.

Cediranib in patients with malignant mesothelioma: a phase II trial of the University of Chicago Phase II Consortium

INTRODUCTION

Malignant mesothelioma (MM) is an aggressive disease with limited therapeutic options. In preclinical models, vascular endothelial growth factor (VEGF) stimulates MM proliferation. In MM patients, higher plasma VEGF levels correlate inversely with survival. Cediranib is an orally administered tyrosine kinase inhibitor of VEGF receptors-1, -2, and -3.

METHODS

We conducted a multi-center phase II trial of cediranib in patients with unresectable, histologically-confirmed MM who had received ≤1 prior regimen of chemotherapy. The primary endpoint was objective response rate. Initial cediranib dosing was 45 mg daily during a 28-day cycle. Due to substantial toxicity, the starting dose was subsequently lowered to 30 mg daily.

RESULTS

Fifty-one patients enrolled at 9 centers; 50 were evaluable for response. Partial responses were observed in 10% of patients; stable disease was seen in 34%. Disease control (PR+SD) was higher at the 45 mg cediranib dose level (67% vs. 34%, p=0.04). Median progression-free survival was 1.8 months (95% CI 0.1, 14.2); median overall survival (OS) was 4.4 months (95% CI 0.9, 41.7). The 1-year survival rate was 15%. Grade 3/4 toxicities were more frequent in the 45 mg dose level group (87% vs. 43%, p=0.002). These included fatigue, hypertension, pulmonary embolism, angioedema, and reversible posterior leukoencephalopathy. Median OS was superior in patients who developed ≥grade 3 hypertension (8.5 vs. 4.1 months, p=0.024).

CONCLUSION

This trial did not meet its pre-specified response endpoint. A higher cediranib dose level was associated with improved disease control, but this dose was poorly tolerated.

Biomarkers that currently affect clinical practice: EGFR, ALK, MET, KRAS

New drugs such as pemetrexed, the epidermal growth factor receptor (egfr) tyrosine kinase inhibitors, and the Alk inhibitor crizotinib have recently enabled progress in the management of advanced non-small-cell lung cancer (nsclc). More drugs, especially Met inhibitors, will follow. However, the benefits of these agents are not uniform across the spectrum of nsclc, and optimizing their utility requires some degree of subgrouping of nsclc by the presence or absence of certain biomarkers.The biomarkers of current or imminent value are EGFR and KRAS mutational status, ALK rearrangements, and MET immunohistochemistry. As a predictor of benefit for anti-egfr monoclonal antibodies, EGFR immunohistochemistry is also of potential interest.Some of the foregoing biomarkers (EGFR, ALK, MET) are direct drivers of the malignant phenotype. As such, they are, quite rationally, the direct targets of inhibitory drugs. However, KRAS, while definitely a driver, has resisted attempts at direct pharmacologic manipulation, and its main value might lie in its role as part of an efficient testing algorithm, because KRAS mutations appear to exclude EGFR and ALK mutations. The indirect value of KRAS in determining sensitivity to other targeted agents or to pemetrexed remains controversial. The other biomarkers (EGFR, ALK, MET) may also have indirect value as predictors of sensitivity to chemotherapy in general, to pemetrexed specifically, and to radiotherapy and molecularly targeted agents.These biomarkers have all enabled the co-development of new drugs with companion diagnostics, and they illustrate the paradigm that will govern progress in oncology in the immediate future. However, in nsclc, the acquisition of sufficient biopsy material remains a stubborn obstacle to the evolution of novel targeted therapies.

Development and validation of a prediction index for hand-foot skin reaction in cancer patients receiving sorafenib

BACKGROUND

This study describes a repeated measures prediction index to identify patients at high risk of ≥grade 2 hand-foot skin reaction (HFSR) before each week of sorafenib therapy.

METHODS

Data from 451 patients who received a sorafenib (400 mg bid) as part of a clinical trial were reviewed (Escudier B, Eisen T, Stadler WM et al. Sorafenib in advanced clear-cell renal-cell carcinoma. N Engl J Med 2007; 356: 125-134). Generalized estimating equations were used to develop the final risk model. A risk-scoring algorithm (range 0-58) was then derived from the final model coefficients. External validation was then carried out on a new sample of 1145 patients who received sorafenib under an expanded access program.

RESULTS

Pretreatment white blood cell count, female gender, good performance status, presence of lung and liver metastases and number of affected organs were predictors for ≥grade 2 HFSR. A nonlinear association between HFSR risk and treatment duration was also identified where risk was maximized at week 5 followed by a gradual decline. Before each week of therapy, patients with risk scores>40 would be considered at high risk for developing ≥grade 2 HFSR.

CONCLUSIONS

The application and planned continued refinement of this prediction tool will be an important source of patient-specific risk information for the development of moderate to severe HFSR.

Cancer: beyond speciation

A good account of the nature of cancer should provide not only a description of its consistent features, but also how they arise, how they are maintained, why conventional chemotherapy succeeds, and fails, and where to look for better targets. Cancer was once regarded as enigmatic and inexplicable; more recently, the "mutation theory," based on random alterations in a relatively small set of proto-oncogenes and tumor suppressor genes, has enjoyed widespread acceptance. The "mutation theory," however, is noticeable for its failure to explain the basis of differential chemosensitivity, for providing a paucity of targets, especially druggable ones, and for justifying the development of targeted therapies with, in general, disappointingly abbreviated clinical benefit. Furthermore, this theory has mistakenly predicted a widespread commonality of consistent genetic abnormalities across the range of cancers, whereas the opposite, that is, roiling macrogenomic instability, is generally the rule. In contrast, concerning what actually is consistent, that is, the suite of metabolic derangements common to virtually all, especially aggressive, cancers, the "Mutation Theory" has nothing to say. Other hypotheses merit serious consideration "aneuploidy theories" posit whole-genome instability and imbalance as causally responsible for the propagation of the tumor. Another approach, that is, "derepression atavism," suggests cancer results from the release of an ancient survival program, characterized by the emergence of remarkably primitive features such as unicellularity, fermentation, and immortality; existential goals are served by heuristic genomic instability coupled with host-to-tumor biomass interconversion, mediated by the Warburg effect, a major component of the program. Carcinogenesis is here seen as a process of de-speciation; however, genomic nonrestabilization raises issues as to where on the tree of life cancers belong, as a genuinely alternative modus vivendi. Philosophical considerations aside, genomic instability offers the prospect of subtle new therapies based on loss of information rather than gain; and the consistent, specific, and broad-spectrum perfidy of the Warburg effect highlights a supplemental target of the highest priority.

Abstract C143: Combining siRNAs targeting thymidylate synthase and thymidine kinase 1 or 2 sensitizes human tumor cells to 5FUdR and pemetrexed

Thymidylate synthase (TS) is the only de novo source of thymidylate (dTMP) for DNA synthesis and repair. Drugs targeting TS protein are a mainstay in cancer treatment, but off-target effects and toxicity limit their use. Cytosolic thymidine kinase (TK1) and mitochondrial thymidine kinase (TK2) contribute to an alternative dTMP-producing pathway, by salvaging thymidine from the tumor milieu, and may modulate resistance to TS-targeting drugs. Combined downregulation of these enzymes is an attractive strategy to enhance cancer therapy. We have previously shown that antisense targeting TS enhanced tumor cell sensitivity to TS-targeting drugs in vitro and in vivo. As both TS and TKs contribute to increased cellular dTMP, we hypothesized that TKs mediate resistance to the capacity of TS siRNA to sensitize tumor cells to TS-targeting anticancer drugs. We assessed the effects of targeting TK1 or TK2 with siRNA alone and in combination with siRNA targeting TS and/or TS-protein targeting drugs on tumor cell proliferation. Downregulation of TK with siRNA enhanced the capacity of TS siRNA to sensitize tumor cells to traditional TS protein-targeting drugs (5FUdR and pemetrexed). The sensitization was greater than that observed in response to any siRNA used alone, and was specific to drugs targeting TS. Upregulation of TK1 in response to combined 5FUdR and TS siRNA suggests that TK knockdown may be therapeutically useful in combination with these agents. TKs may be useful targets for cancer therapy when combined with molecules targeting TS mRNA and TS protein.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C143.

Combining small interfering RNAs targeting thymidylate synthase and thymidine kinase 1 or 2 sensitizes human tumor cells to 5-fluorodeoxyuridine and pemetrexed

Thymidylate synthase (TS) is the only de novo source of thymidylate (dTMP) for DNA synthesis and repair. Drugs targeting TS protein are a mainstay in cancer treatment, but off-target effects and toxicity limit their use. Cytosolic thymidine kinase (TK1) and mitochondrial thymidine kinase (TK2) contribute to an alternative dTMP-producing pathway, by salvaging thymidine from the tumor milieu, and may modulate resistance to TS-targeting drugs. Combined down-regulation of these enzymes is an attractive strategy to enhance cancer therapy. We have shown previously that antisense-targeting TS enhanced tumor cell sensitivity to TS-targeting drugs in vitro and in vivo. Because both TS and TKs contribute to increased cellular dTMP, we hypothesized that TKs mediate resistance to the capacity of TS small interfering RNA (siRNA) to sensitize tumor cells to TS-targeting anticancer drugs. We assessed the effects of targeting TK1 or TK2 with siRNA alone and in combination with siRNA targeting TS and/or TS-protein targeting drugs on tumor cell proliferation. Down-regulation of TK with siRNA enhanced the capacity of TS siRNA to sensitize tumor cells to traditional TS protein-targeting drugs [5-fluorodeoxyuridine (5FUdR) and pemetrexed]. The sensitization was greater than that observed in response to any siRNA used alone and was specific to drugs targeting TS. Up-regulation of TK1 in response to combined 5FUdR and TS siRNA suggests that TK knockdown may be therapeutically useful in combination with these agents. TKs may be useful targets for cancer therapy when combined with molecules targeting TS mRNA and TS protein.

Optimizing the management of advanced non-small-cell lung cancer: a personal view

The management of advanced non-small-cell lung cancer (a-nsclc) is currently undergoing one of its rare paradigm shifts. Just as the nihilism of the 1970s gave way to the empiricism of the 1980s and 1990s, so the current decade has seen the first truly rational therapies based on informed design. In addition, molecular markers and traditional parameters can now be combined to provide a framework of knowledge that will guide the application of not just the new therapies, but also the older ones that remain effective. This framework—as important a component of the rational paradigm as the new drugs themselves are—is necessary to decide who should and, crucially, who should not receive the various components of this rapidly expanding armamentarium. Here, I have provided a historical overview of the drug treatment of a-nsclc, a mini-review of important new data, and an integrative approach that tries to ensure that patients receive the optimal treatment choice at the appropriate time.

The speed at which new knowledge now arrives, coupled with the persistent high level of unmet medical need, suggests that the traditional pace of evidence-based review needs to be accelerated. Indeed, the increased scope for personalized management constitutes something of a challenge to “business as usual” evidence-based medicine. As a result, substantial investment on the part of payers, which may or may not be possible, will be required. In the meantime, some patients may wish and may be financially able to take advantage of modern developments before they have been fully digested by the public-payer system. Responsive clinicians face difficult tradeoffs as they try to balance the pros and cons of early adoption versus excessive conservatism.

The present article is my personal view of how to navigate these waters, and although it is written especially for patients who like to be the captain of their own ship, there is good reason to believe that all patients will eventually be managed by similar, if not identical, means. Nonetheless, the recommendations herein should not be construed as appropriately reviewed provincial or national guidelines. Finally, if appropriate, a clinical trial should always be offered.

The animal within: carcinogenesis and the clonal evolution of cancer cells are speciation events sensu stricto

Heritable genomic variation and natural selection have long been acknowledged as striking parallels between evolution and cancer. The logical conclusion, that cancer really is a form of speciation, has seldom been expounded directly. My purpose is to reexamine the "cancer as species" thesis in the light of current attitudes to asexual speciation, and modern analyses of species definitions. The chief obstacles to accepting this thesis have been the asexual nature of cancer cell reproduction, the instability of the malignant genotype and phenotype, and our conditioning that speciation is an extremely rare and imperceptibly gradualistic process. However, these are not absolute barriers to the acceptance of cancers as bona fide species. Furthermore, although ongoing clonal evolution of extant cancers also results in a series of secondary speciation events, the initial emergence of a cancer requires a level of taxonomic reclassification even beyond the concept of speciation (i.e., phylogenation), and which is almost certain to provide a rich source of novel drug targets. The implications of the "cancer as species" idea may be as important for biology as for oncology, providing as it does an endless supply of observable if accelerated examples of a phenomenon once regarded as rare. From the perspective of cancer treatment, speciation guarantees the existence of causal molecular mechanisms which may have been neglected as exploitable targets for rational therapy; in particular, the mediators of metazoan life seem to have substantial overlap with components commonly deranged in cancer cells. However, the intractability of the drug resistance problem, residing as it does in the inherent plasticity of the genome, is traceable back to, and inseparable from, the very origins and nature of life.

Prevention and management of chemotherapy-induced diarrhea in patients with colorectal cancer: a consensus statement by the Canadian Working Group on Chemotherapy-Induced Diarrhea

Chemotherapy-induced diarrhea (cid) is a common side effect of cancer treatment and can cause significant morbidity and mortality. Diarrhea is frequently severe enough to require a dose reduction of, a delay in, or a discontinuation of chemotherapy. Diarrhea-associated mortality has been reported to be as high as 3.5% in clinical trials of irinotecan and bolus 5-fluorouracil in colorectal cancer. The frequency of cid and its impact on patient management are frequently under-recognized in clinical practice.A Canadian working group, consisting of medical oncologists and an oncology pharmacist, was formed in 2001 to review the optimal approach to managing cid and to identify and implement new areas of research. The recommendations that follow are the result of the group's work.Acute medical management of cid includes loperamide or diphenoxylate as first-line agents. Subcutaneous octreotide is recommended for intractable grade 2 diarrhea and may be considered for grade 1 cid that does not resolve with high-dose loperamide. Hospitalization is recommended for patients with grades 3 and 4 cid; in-hospital care includes rehydration, antibiotic therapy, and octreotide.A chemotherapy dose reduction is generally advised for patients who have experienced grade 3 or 4 diarrhea in a previous chemotherapy cycle. If a dose reduction is not desired, prophylaxis with intramuscular long-acting release octreotide may be considered.The foregoing recommendations are based on expert opinion and require validation in prospective clinical trials.

Randomized, double-blind trial of carboplatin and paclitaxel with either daily oral cediranib or placebo in advanced non-small-cell lung cancer: NCIC clinical trials group BR24 study

PURPOSE This phase II/III double-blind study assessed efficacy and safety of cediranib with standard chemotherapy as initial therapy for advanced non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS Paclitaxel (200 mg/m(2)) and carboplatin (area under the serum concentration-time curve 6) were given every 3 weeks, with daily oral cediranib or placebo at 30 mg (first 45 patients received 45 mg). Progression-free survival (PFS) was the primary outcome of the phase II interim analysis; phase III would proceed if the hazard ratio (HR) for PFS < or = 0.77 and toxicity were acceptable. Results A total of 296 patients were enrolled, 251 to the 30-mg cohort. The phase II interim analysis demonstrated a significantly higher response rate (RR) for cediranib than for placebo, HR of 0.77 for PFS, no excess hemoptysis, and a similar number of deaths in each arm. The study was halted to review imbalances in assigned causes of death. In the primary phase II analysis (30-mg cohort), the adjusted HR for PFS was 0.77 (95% CI, 0.56 to 1.08) with a higher RR for cediranib than for placebo (38% v 16%; P < .0001). Cediranib patients had more hypertension, hypothyroidism, hand-foot syndrome, and GI toxicity. Hypoalbuminemia, age > or = 65 years, and female sex predicted increased toxicity. Survival update (N = 296) 10 months after study unblinding favored cediranib over placebo (median of 10.5 months v 10.1 months; HR, 0.78; 95% CI, 0.57 to 1.06; P = .11). Causes of death in the cediranib 30-mg cohort were NSCLC (81%), protocol toxicity +/- NSCLC (13%), and other (6%); for the placebo group, they were 98%, 0%, and 2%, respectively. CONCLUSION The addition of cediranib to carboplatin/paclitaxel results in improved response and PFS, but does not appear tolerable at a 30-mg dose. Consequently, the National Cancer Institute of Canada Clinical Trials Group and the Australasian Lung Cancer Trials Group initiated a randomized, double-blind, placebo-controlled trial of cediranib 20 mg with carboplatin and paclitaxel in advanced NSCLC.

Enhancement of cytotoxicity of natural product drugs against multidrug resistant variant cell lines of human head and neck squamous cell carcinoma and breast carcinoma by tesmilifene

N,N-diethyl-2-[4-(phenylmethyl)phenoxyl]ethanamine (tesmilifene), a tamoxifen derivative with antihistamine activity, greatly enhanced the survival of doxorubicin-treated, advanced stage breast cancer patients in a phase III trial. However, the molecular basis of tesmilifene action is not firmly established. The effects of tesmilifene on activity of several anticancer drugs was investigated using human head and neck squamous cell carcinoma (HNSCC) and breast carcinoma cell lines as a model system. Multidrug resistant (MDR) variants of an HNSCC cell line, HN-5a/V15e, and a breast carcinoma cell line, MCF-7/V25a, both highly overexpressed mdr1 (ABCB1) mRNA and the proteins P-glycoprotein and glutathione transferase-pi. Drug sensitivities were measured by a vital stain after 4 days of continuous exposure to anticancer drug in the absence and presence of tesmilifene at a concentration that alone had no antiproliferative effect. Tesmilifene had minimal effect on drug cytotoxicity against the parental cell lines. However, the same tesmilifene treatment enhanced cytotoxicity of docetaxel, paclitaxel, epirubicin, doxorubicin, and vinorelbine against both MDR cell lines by up to 50%. Flow cytometric measurement of annexin V/propidium iodide staining demonstrated that tesmilifene increased the killing of HN-5a/V15e cells caused by docetaxel after 24 and 48h exposure. Tesmilifene increased accumulation of radiolabelled vincristine in HN-5a/V15e cells, over 4h, by up to 100%. The results suggest that tesmilifene might be effective in the treatment of tumors that are resistant to natural product drugs. The mechanism of enhancement appears to be related to expression of an ABC pump-dependent, MDR phenotype.

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.

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.

Does sex influence the impact that smoking, treatment interruption and impaired pulmonary function have on outcomes in limited stage small cell lung cancer treatment?

PURPOSE

To look for survival differences between men and women with limited stage small cell lung cancer (LS-SCLC) by examining stratified variables that impair treatment efficacy.

METHODS

A retrospective review of 215 LS-SCLC patients treated from 1989 to 1999 with concurrent chemotherapy-radiotherapy modelled on the 'early-start' thoracic radiotherapy arm of a National Cancer Institute of Canada randomized trial.

RESULTS

Of 215 LS-SCLC patients, 126 (58.6%) were men and 89 (41.4%) were women. Smoking status during treatment for 186 patients (86.5%) was: 107 (58%) nonsmoking (NS) (76 [71%] male [M]; 31 [29%] female [F]) and 79 (42%) smoking (S) (36 M [46%]; 43 F [54%]) (continuing-to-smoke F versus M, P=0.001). Fifty-six patients (26%) had radiotherapy interruptions (RTI) during chemotherapy-radiotherapy because of toxicity. Radiotherapy breaks were not associated with sex (P=0.95). Survival by sex and smoking status at two years was: F + NS = 38.7%; F + S = 21.6%; M + NS = 22.9%; and M + S = 9.1% (P=0.0046). Survival by sex and RTI status at two years was: F + no RTI = 32.4%; F + RTI = 23.6%; M + no RTI = 23.0%; and M + RTI = 3.8% (P=0.0025). Diffusion capacity for carbon monoxide (DLCO) was recorded for 86 patients (40%) and median survival by sex and DLCO was F = 16.7 months and M = 12.1 months for a DLCO less than 60%; and for a DLCO 60% or more, F = 15.1 months and M = 15.3 months. First relapses were recorded in 132 cases (61%), with chest failure in men (45%) greater than for women (35%) and cranial failure rates similar between sexes (48%). Upon multivariable analysis, continued smoking was the strongest negative factor affecting survival.

CONCLUSIONS

In LS-SCLC, women overall do better than men, with or without a negative variable. The largest quantifiable improvement in survival for women came from smoking cessation, and for men from avoidance of breaks during 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.

A "combination oligonucleotide" antisense strategy to downregulate thymidylate synthase and decrease tumor cell growth and drug resistance

Thymidylate synthase (TS) catalyzes de novo production of thymidylate for DNA synthesis and cell proliferation. As such, TS has been a target of antitumor chemotherapy for many years. Our laboratory has identified several antisense oligodeoxynucleotides (ODNs) that downregulate TS mRNA and protein, inhibit cell proliferation, and sensitize cells to TS-directed chemotherapeutic drugs. Based on our observation that targeting distinct regions of the TS mRNA with a variety of antisense molecules resulted in differential effects on TS mRNA levels, it was hypothesized that use of multiple ODNs targeting distinct noncontiguous regions would result in synergistic or antagonistic interactions. In this study, we report that some combinations of TS antisense ODNs were more effective at reducing TS mRNA abundance and inhibiting cell proliferation than the individual ODNs used alone. However, in contrast to the effects on cell proliferation, the enhanced sensitivity to anti-TS chemotherapeutic drugs (i.e., raltitrexed and 5-fluorodeoxyuridine) that is achieved by treatment with individual ODNs was not further augmented by combined ODN treatment. This suggests that ODNs targeting TS mRNA inhibit an alternative function of TS mRNA or protein, distinct from thymidylate production. The results are evidence that the novel use of multiple antisense ODNs that target different regions of the same mRNA represents a general strategy to improve antisense effectiveness.

Primary chemoradiation as definitive treatment for unresectable cancer of the trachea

A 64-year-old man was diagnosed with unresectable cancer of the trachea. He was treated definitively with a novel chemoradiation regimen. Cisplatin-based chemotherapy (ChT) was given for two cycles as induction, followed by concurrent administration of this ChT with external beam radiotherapy (RT) (total dose 60 Gy). An unexpected partial tumour response was noted after the induction of ChT alone. Six weeks after finishing ChT/RT, complete response of the lesion was noted on computed tomography imaging. Two years later, the patient was free of disease. Primary chemoradiation appears to be effective in managing locally advanced tracheal cancer.

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.

Antisense-induced down-regulation of thymidylate synthase and enhanced cytotoxicity of 5-FUdR in 5-FUdR-resistant HeLa cells

1. Thymidylate synthase (TS) is a target for several anticancer drugs. We previously showed that an antisense oligodeoxynucleotide (ODN) directed against TS mRNA down-regulated TS protein and enhanced cytotoxicity of TS-targeting drugs [including 5-fluorodeoxyuridine (5-FUdR)] in HeLa cells. Patient tumours with increased TS expression are resistant to TS-targeting drugs. It was hypothesized that TS mRNA and consequently TS protein could be down-regulated in 5-FUdR-resistant cells that overexpress TS, sensitizing them to 5-FUdR cytotoxicity. In this study we assessed the capacity of an anti-TS antisense ODN to circumvent resistance dependent on TS overexpression. 2. Variant HeLa clones exhibiting 2 - 20 fold resistance to 5-FUdR were selected by exposing cultured cells to drug. Clones FUdR-5a, -25b, and -50a expressed TS protein levels 10 fold, 10 fold, and 17 fold higher (respectively) than parental cells. Cells were treated with antisense ODN 83 (a 2'-methoxy-ethoxylated, phosphorothioated 20-mer, complementary to a portion of the 3'-untranslated region of TS mRNA), or ODN 32 (a control ODN with the same base composition as ODN 83, but in randomized order). Twenty-four and 48 h following transfection (50-100 nM ODN, plus polycationic liposome), TS mRNA levels (by RT-PCR) and protein levels (by radiolabelled 5-FUdR-monophosphate binding) were decreased by at least 60% in ODN 83-treated cells compared with control ODN 32-treated cells. ODN 83 enhanced the cytotoxicity of 5-FUdR by up to 85% in both parental and 5-FUdR-resistant cell lines. 3. Antisense ODN can be used to down-regulate TS and attenuate drug resistance in TS-overexpressing cells.

Using treatment interruptions to palliate the toxicity from concurrent chemoradiation for limited small cell lung cancer decreases survival and disease control

BACKGROUND AND PURPOSE

We analyzed the impact on survival outcomes of treatment interruptions due to toxicity arising during the concurrent phase of chemotherapy/radiotherapy (ChT/RT) for our limited-stage small-cell cancer (LSCLC) population over the past 10 years.

MATERIALS AND METHODS

From 1989 to 1999, 215 patients received treatment for LSCLC, consisting of six cycles of alternating cyclophosphamide/doxorubicin or epirubicin/vincristine (CAV; CEV) and etoposide/cisplatin (EP). Thoracic RT was started with EP at either the second or third cycle (85% of patients). RT dose was either 40 Gy in 15 fractions over 3 weeks or 50 Gy in 25 fractions over 5 weeks, delivered to a target volume encompassing gross disease and suspected microscopic disease with a 2 cm margin. Treatment breaks arising during concurrent ChT+RT were used to manage severe symptomatic or hematologic toxicities. We used the interruptions in thoracic RT as the 'marker' for any concurrent break and measured 'break duration' by the total length of time (in days) RT was interrupted, since that also signaled that ChT could be re-initiated. Patient results were analyzed for the impact of interruptions/treatment prolongation on overall and disease-free survival.

RESULTS

For all patients, 2-year and 5-year overall and disease-specific survivals were 22.7 and 7.2, 27.6 and 9.3%, respectively; overall and disease-specific median survivals were 14.7 months each. A total of 56 patients (26%) had treatment breaks due to toxicity. Hematologic depression caused the majority of breaks (88%). The median duration of breaks was 5 days (range 1-18). Patients with and without interruptions were compared for a range of prognostic factors and were not found to have any significant differences. Comparing interrupted/uninterrupted courses, median survivals were 13.8 versus 15.6 months, respectively, and 5-year overall survivals were 4.2 versus 8.3%, respectively. There was a statistical difference between overall survival curves which favored the uninterrupted group (P=0.01). When comparing a series of prognostic variables, multivariable analysis found that the most significant factor influencing survival in the present study was the presence of treatment breaks (P=0.006). There was a trend for development of any recurrence in the patients with breaks (P=0.08). When controlling for the use of prophylactic cranial irradiation (PCI) in the two groups, the rate of failure in the chest was higher in the patients with RT breaks (58 vs. 33%). The rate of failure in the brain was dependent on the use of PCI only.

CONCLUSIONS

Interruptions in treatment to palliate the toxicity from concurrent chemoradiation result in poorer local control and decreased survival.

Enhancement of platinum-drug cytotoxicity in a human head and neck squamous cell carcinoma line and its platinum-resistant variant by liposomal amphotericin B and phospholipase A2-II

Platinum drugs comprise one of the main classes of chemotherapy drugs that can induce remissions in various solid tumors. Although tumors often regress on treatment with cis-diamminedichloroplatinum II (cisplatin) or cis-diammine-1,1-cyclobutane dicarboxylate platinum II (carboplatin), they usually relapse as a drug-resistant tumor. Most mechanisms of platinum resistance could be overcome by increasing the amount of drug that is accumulated by tumor cells. Amphotericin B (Amph B) is efficient at increasing platinum drug uptake, but because of nephrotoxicity associated with extended usage, and the potential for synergistic nephrotoxicity when used with platinum drugs, Amph B has not been used clinically for this purpose. A liposomal preparation of Amph B (LipoAmph B), which is substantially less nephrotoxic, was studied for its ability to enhance platinum-drug toxicity to a human oral squamous cell carcinoma line, HN-5a, and its carboplatin-resistant variant, 5a/carbo-15a, in which cisplatin accumulation was reduced by approximately 40%. Amph B at 10 microg/ml enhanced cisplatin accumulation by approximately 100% in both cell lines, enhancing cytotoxicity of the drugs by 35 to 60%, and completely reversed resistance to both cisplatin and carboplatin. LipoAmph B in the presence of phospholipase A(2)-II (PLA2-II) was able to enhance cisplatin and carboplatin cytotoxicity as effectively as free Amph B in both cell lines. At optimal concentrations, LipoAmph B plus PLA2-II enhanced drug uptake sufficiently to abolish resistance in the platinum-resistant line. Because PLA2-II is elevated in some tumor microenvironments and in plasma of ill patients, LipoAmph B has potential clinical usefulness as a modulator of platinum-drug efficacy.

Antisense down-regulation of thymidylate synthase to suppress growth and enhance cytotoxicity of 5-FUdR, 5-FU and Tomudex in HeLa cells

1. Thymidylate synthase (TS), the key enzyme in de novo synthesis of thymidine, is an important target for antitumour chemotherapy. It was hypothesized that antisense oligonucleotide down-regulation of TS mRNA would decrease TS levels and enhance the cytotoxicity of inhibitors of TS, including the pyrimidine analogues 5-fluorouracil (5-FU) and 5-fluorodeoxyuridine (5-FUdR), and the folate analogue Tomudex (ICI D1694; N-(5-[N-(3, 4-dihydro-2-methyl-4-oxoquinazolin-6-ylmethyl)-N-methylamino ]-2-theon yl-L-glutamic acid). 2. 2'-Methoxyethoxylated, phosphorothioated 20-mer oligodeoxynucleotides (ODNs), complementary to various sequences in TS mRNA, were synthesized, along with control oligomers consisting of the same, respective bases in randomized order, against which all the biological effects were compared. Following a 6-h transfection of HeLa cells using polycationic liposome at 3 microg ml(-1), ODN 83 (50 nM), complementary to a region in the 3'-untranslated region of the TS mRNA, decreased TS mRNA levels by approximately 70% within 24 h. ODN 83 also decreased TS enzyme activity, as measured by binding of TS to radiolabelled 5-fluorodeoxyuridine monophosphate. In addition to inhibiting proliferation by up to approximately 40%, ODN 83 enhanced the cytotoxicity of Tomudex or 5-FU, added 1 day following transfection, by 50 - 60%. ODN 83 also enhanced sensitivity to 5-FUdR by 70%, but did not affect the toxicity of cisplatin, chlorambucil, melphalan, doxorubicin, ionizing radiation, paclitaxel, or irinotecan. 3. These data indicate that antisense ODN down-regulation of TS can inhibit human tumour cell proliferation and enhance the efficacy of TS-targeted drugs.