Abstract P207: BBP-398, a potent, small molecule inhibitor of SHP2, enhances the response of established NSCLC xenografts to KRASG12C and mutEGFR inhibitors

Src homology 2 domain-containing phosphatase (SHP2), a ubiquitously expressed non-receptor tyrosine phosphatase, plays a critical role in the regulation of the MAPK signaling pathway and cellular proliferation. Activating mutations in SHP2 are associated with the development of multiple malignancies including leukemia, lung cancer and neuroblastoma. In addition, SHP2 promotes the conversion of oncogenic KRAS to its active GTP-bound state and it’s inhibition can enhance efficacy of GDP-KRASG12C inhibitors as well as other MAPK pathway inhibitors (RAF, MEK and ERK) which have suboptimal clinical efficacy as single agents. As a result, inhibition of SHP2 through genetic manipulation or pharmacological means has been shown to suppress tumor growth and presents an attractive potential avenue for the treatment of malignancies as monotherapy or in combination with other MAPK/PI3K inhibitors. Here we describe BBP-398, a potent, orally bioavailable allosteric small molecule inhibitor of SHP2. BBP-398 displays high selectivity against other phosphatases, kinases, GPCRs, transporters and hERG. Predicted human PK properties show good oral bioavailability with half-life of ~12-16 hours enabling continuous daily dosing and optimal therapeutic index in combination with other targeted therapeutics. In cellular assays, BBP-398 demonstrates potent pERK/DUSP6 inhibition and loss of viability across a panel of cell lines with active MAPK signaling, such as mutant EGFR and KRASG12C. In vivo, BBP-398 strongly suppresses RAS-ERK signaling in RTK- or RAS-driven xenografts. In the EGFR-dependent non-small cell lung cancer (NSCLC) HCC827 and esophageal squamous cell carcinoma KYSE-520 xenograft models, BBP-398 drives dose dependent efficacy consistent with the level of target inhibition. Detailed analysis of tumor response shows that efficacy is driven by maintaining better than 50% inhibition of pERK for most of the dosing interval. In addition to its strong single agent activity, BBP-398 also leads to enhanced efficacy in vitro and in vivo when used in combination with targeted therapeutics against driver MAPK genetic alterations, such as KRAS, EGFR or MET. Combination targeting, such as with the GDP-KRASG12C inhibitor sotorasib in the NSCLC NCI-H358 xenograft model, or with the mutant EGFR inhibitor osimertinib in the HCC827 erlotinib resistant (ER) xenograft model, drives strong suppression of MAPK activity and results in tumor regressions. Collectively, these findings highlight that SHP2 inhibition is a promising molecular therapeutic strategy in cancer which can potentially strongly suppress tumor growth as a single agent or in combination with other MAPK pathway inhibitors. Given its preclinical properties and projected favorable clinical pharmacokinetic profile, BBP-398 is currently being evaluated in a Phase 1/1b trial in patients with advanced solid tumors (NCT04528836).

Citation Format: James P. Stice, Sofia Donovan, Yuting Sun, Nancy Kohl, Barbara Czako, Faika Mseeh, Paul Leonard, Anna Wade, Justin Lim, Phil Jones, Eli Wallace, Kerstin Sinkevicius, Pedro Beltran. BBP-398, a potent, small molecule inhibitor of SHP2, enhances the response of established NSCLC xenografts to KRASG12C and mutEGFR inhibitors [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P207.

Lymph node yield in right colectomy for cancer: a comparison of open, laparoscopic and robotic approaches

AIM

Studies have demonstrated a relationship between lymph node (LN) yield and survival after colectomy for cancer. The impact of surgical technique on LN yield has not been well explored.

METHOD

This is a retrospective study of right colectomy (RC) for cancer at a single institution from 2012 to 2014. Exclusion criteria were previous colectomy and emergent and palliative operations. All data were collected by chart review. Primary outcomes were LN yield and the LN to length of surgical specimen (LN-LSS) ratio. Multivariable mixed models were created with surgeon and pathologist as random effects. Sensitivity analyses were performed to exclude Stage IV cancers and to analyse groups on an 'as-treated' basis.

RESULTS

We identified 181 open (O-RC), 163 laparoscopic (L-RC) and 119 robotic (R-RC) right colectomies. O-RC was more commonly performed in women with metastatic disease. The mean LN yield was 28, 29 and 34 in O-RC, L-RC and R-RC, respectively; the respective mean LN-LSS ratios were 0.83, 0.91 and 1.0. The R-RC approach produced a higher LN yield than the other approaches (P < 0.01), and a higher LN-LSS ratio than O-RC (P < 0.01). These findings were unchanged in sensitivity analyses.

CONCLUSION

Robotic right colectomy improves LN yield and the LN-LSS ratio, which may reflect better mesocolic excision. The effect of these findings on survival requires further investigation.

Ascariasis as cause of intestinal occlusion and concurrent appendicitis

Intestinal occlusion by ascariasis is a commonly seen socio-economic status low, is associated with poor sanitary hygiene. It is rare to see a case with both intestinal occlusion and appendicitis at the same time, as described in this report.

Incisional hernias after laparoscopic and robotic right colectomy

PURPOSE

Incisional hernia (IH) is a common complication after colectomy, with impacts on both health care utilization and quality of life. The true incidence of IH after minimally invasive colectomy is not well described. The purpose of this study was to examine IH incidence after minimally invasive right colectomies (RC) and to compare the IH rates after laparoscopic (L-RC) and robotic (R-RC) colectomies.

METHODS

This is a retrospective review of patients undergoing minimally invasive RC at a single institution from 2009 to 2014. Only patients undergoing RC for colonic neoplasia were included. Patients with previous colectomy or intraperitoneal chemotherapy were excluded. Three L-RC patients were included for each R-RC patient. The primary outcome was IH rate based on clinical examination or computed tomography (CT). Univariate and multivariate time-to-event analyses were used to assess predictors of IH.

RESULTS

276 patients where included, of which 69 had undergone R-RC and 207 L-RC. Patient and tumor characteristics were similar between the groups, except for higher tumor stage in L-RC patients. Both the median time to diagnosis (9.2 months) and the overall IH rate were similar between the groups (17.4 % for R-RC and 22.2 % for L-RC), as were all other postoperative complications. In multivariable analyses, the only significant predictor of IH was former or current tobacco use (hazard raio 3.0, p = 0.03).

CONCLUSIONS

This study suggests that the incidence of IH is high after minimally invasive colectomy and that this rate is equivalent after R-RC and L-RC. Reducing the IH rate represents an important opportunity for improving quality of life and reducing health care utilization after minimally invasive colectomy.

Abstract 2346: Intratumoral administration of OncoVEXmGM-CSF results in local innate immune alterations and induces systemic anti-tumor effects in syngeneic mouse tumor models

Talimogene laherparepvec, is a modified oncolytic herpes simplex virus type-1 (HSV-1) designed to selectively replicate in tumors and to initiate a systemic immune response to target cancer cells. Intralesional administration of talimogene laherparepvec is intended to result in oncolysis within injected tumors, with lytic cell destruction promoting the local release of progeny virus and tumor derived antigens. GM-CSF, a product of the viral transgene, is also produced locally and is designed to recruit and stimulate antigen presenting cells to further enhance systemic antitumor immune response.

While available evidence suggests that talimogene laherparepvec can induce effects in distant tumors via an immune-mediated effect, additional mechanistic evidence is being sought to help better understand the putative systemic effect. For preclinical mechanism of action studies we employed OncoVEXmGM-CSF, an HSV-1 virus modified in the same manner as talimogene laherparepvec except that murine GM-CSF is expressed. We utilized this virus to further dissect the underlying innate and adaptive immunity following viral administration in syngeneic tumor models.

Intratumoral administration of OncoVEXmGM-CSF into established murine tumors induced regressions in the injected lesion but also resulted in significant anti-tumor effects in contralateral (uninjected) lesions. We have previously demonstrated by immunohistochemistry that the systemic effects observed in the contralateral lesions are not driven by systemic spread of the virus, but instead correlate with the infiltration of CD3+ T cell populations. Here we report the full phenotypic characterization of immune infiltrates by flow cytometry in both the injected and contralateral lesions. In a time-course fashion, this characterization revealed the initial infiltration of the injected tumor by innate effector cells and a concomitant induction of a potent type I interferon response. This in turn drives the local release of proinflammatory cytokines and chemokines, resulting in the recruitment of adaptive immune subsets to the injected tumor and enhancing systemic anti-tumor reactivity. Additionally, both the primary oncolytic replication of the virus and the activation of type I interferon pathway are directly correlated with STING activity.

In conclusion, in vitro and in vivo observations suggest that intratumoral injection of OncoVEXmGM-CSF activates multiple immune-mediated mechanisms of action leading to T-cell activation and induction of anti-tumor immunity in mice.

Citation Format: Keegan Cooke, Karen Fitzgerald, Becky Yang, Juan Estrada, Brian Belmontes, Pedro Beltran, Achim K. Moesta. Intratumoral administration of OncoVEXmGM-CSF results in local innate immune alterations and induces systemic anti-tumor effects in syngeneic mouse tumor models. [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 2346.

Abstract 4038: Developmentof a murine tumor immunophenotyping platform to support drug discovery anddevelopment in immuno-oncology

Recent clinical data highlights the importance of immune cell localization, phenotype, and gene signature as it correlates to a productive anti-tumor response. Preclinically, multiple syngeneic mouse models have been used to study the effects of immunomodulation and define anti-tumor responses to transplanted “self” tumors. However, while the literature describes distinct aspects of many of these models, there is no comprehensive dataset comparing and contrasting their tumor-immune microenvironments across models. These data are critical for better understanding the role that various immune populations play in the anti-tumor response and interpreting observed changes in tumor clearance following treatment with immunomodulatory agents. We have therefore established a platform that 1) quantitates the types of immune cells within murine tumor models, and 2) describes the location of these cells within the tumor. In parallel to the immunophenotyping efforts we have benchmarked tumor models based on their response to antibodies against T cell checkpoint pathways.

We sought to use this immunophenotyping platform to identify specific immune modulation that occurs in syngeneic tumors post depletion of macrophages via CSF1R blockade. Tumor-associated macrophages (TAMs) are believed to help promote tumor survival through suppression of the adaptive immune response and the secretion of growth factors that promote tumor growth and angiogenesis. Therefore depletion of TAMs should lead to T-cell recruitment and bolster the antitumor T-cell response. Here we show that treatment of CT-26 and RENCA syngeneic tumors with a CSF1R antagonist leads to depletion of MHCII+ and F4/80+ expressing cells. Future experiments will seek to understand if CSF1R blockade improves the response to T-cell checkpoint immunotherapies. In summary, the development of a murine tumor immunophenotyping platform has allowed insight and evaluation of immune cells in the tumor microenvironment that can ultimately be leveraged to understand the synergistic effects of immunotherapeutics.

Citation Format: Brian Belmontes, Stephanie Matyas, Sarah O’Brien, Hong Tan, Kenneth Ganley, Kimberly Merriam, Jim Rottman, Jackson Egen, Pedro Beltran, Gordon Moody. Developmentof a murine tumor immunophenotyping platform to support drug discovery anddevelopment in immuno-oncology. [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 4038.

Abstract 2861: Validation of PERK as an oncology target: A role for the unfolded protein response in cancer

The Unfolded Protein Response (UPR) is a cellular stress response to stressors that induce accumulation of unfolded proteins in the endoplasmic reticulum (aka ER stress). The UPR protects cells from ER stress by increasing the capacity of the ER and attenuating bulk translation. Intense or unresolved ER stress induces apoptosis through pro-apoptotic factors like CHoP. The UPR is activated in tumors, especially those of hematological origin. PERK, a UPR sensor-kinase, is highly active in these settings and might be an attractive target in oncology.

We have generated multiple potent, selective PERK inhibitor scaffolds. Low doses of PERK inhibitor (&lt; pPERK IC50) activate the downstream pathway, whereas higher doses return the pathway to baseline, resulting in a bell-shaped activity curve for all pathway readouts. The activation phase results in robust, selective killing of tumor cells in vitro and in vivo, likely through sustained translation inhibition and CHoP induction. However, application in the clinic will be challenging due to irreversible toxicity to pancreatic islets at constant, high doses and difficulty managing human dosing through a bell curve.

Emerging data might provide a solution to these challenges. PERK IP-kinase assays demonstrate that compound binding at any dose activates PERK and this activity is retained after compound removal. Exposure modeling in vitro demonstrates that transient dosing followed by compound removal results in a conventional sigmoidal dose-response curve for viability. Intermittent dosing in vivo results in CHoP induction and tumor growth inhibition even at very high doses of PERK, consistent with PERK activation following compound clearance. These findings suggest that optimized scheduling might drive robust tumor growth inhibition with reduced risk of toxicity and facilitate a standard clinical dose escalation.

Citation Format: Ken Dellamaggiore, Petia Mitchell, Ji-Rong Sun, Jeffrey Jones, Tony Muchamuel, David Hollenback, Seifu Tadesse, Shon Booker, Fang-Tsao Hong, Adrian Smith, Mark Rose, Pedro Beltran, James R. Lipford. Validation of PERK as an oncology target: A role for the unfolded protein response in cancer. [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 2861.

Abstract 3712: HGF mediated resistance to BRAF inhibition in BRAF V600E mutant melanoma xenograft models

Background: A key obstacle in the treatment of cancer is resistance to targeted therapy. Recent reports suggest that growth factors and their receptors may play a role in mediating this resistance. HGF/MET signaling has been shown to play a role in mediating resistance to BRAF inhibitors in BRAF mutant melanoma. We studied the role of HGF/MET in mediating resistance to BRAF inhibition in BRAF mutant melanoma xenografts, comparing models of systemic and local HGF expression and evaluating the ability of a MET inhibitor to reverse HGF mediated resistance. The underlying mechanisms of this resistance were evaluated by monitoring changes in PI3K and MAPK signaling. Our data suggest that elevated local HGF expression may be required for resistance to BRAF inhibition in vivo and that resistance can be reversed by treatment with a MET inhibitor.

Methods: To model systemic HGF expression, mice bearing G361 melanoma xenografts were treated with recombinant adeno-associated virus containing an expression cassette for human HGF (AAV-HGF) or GFP as control. Mice were treated with C-1 (10 mg/kg, QD, PO), a BRAF inhibitor, or vehicle, and tumor growth was monitored. Local HGF expression was modeled using G361 xenografts engineered to express HGF under the control of an inducible promoter (tet-HGF). Mice bearing G361 tet-HGF xenografts, with or without doxycycline, were treated and monitored as described above. A follow up study was performed in G361 tet-HGF xenografts to measure the ability of AMG 337 (20 mg/kg, BID, PO), a selective MET inhibitor, to attenuate the HGF mediated rescue of BRAF inhibition. To monitor effects on the PI3K and MAPK pathways, pAKT and pERK levels were measured in tumors. Plasma and tumor HGF levels were also measured.

Results: Systemic expression of HGF via AAV-HGF treatment failed to rescue G361 xenografts from the growth inhibitory effects of C1. In contrast, local doxycycline-induced expression of HGF in mice harboring G361 tet-HGF xenografts conveyed significant (p&lt;0.001) rescue of tumor growth, suggesting that local HGF expression may be required to mediate BRAF inhibitor resistance. Elevated pAKT and pERK levels were detected in HGF rescued tumors, suggesting that PI3K and MAPK signaling pathways play a role in conveying HGF mediated resistance. Combined treatment with AMG 337 prevented the HGF mediated rescue of BRAF inhibition, confirming the role of MET signaling in this rescue mechanism. Plasma HGF levels in mice from the systemic HGF expression groups exceeded those in the local groups (3,049 and 195 pg/mL). However, tumor HGF levels were higher in the local expression groups compared to the systemic groups (26,400 and 477 pg/mL).

Conclusion: Here we demonstrate the role for HGF/MET signaling in mediating resistance to BRAF inhibitors in melanoma and suggest that monitoring HGF levels may be of clinical utility for predicting response to BRAF inhibition and in defining the opportunity for combination therapy with MET inhibitors.

Citation Format: Keegan Cooke, Guo Huang, Sean Caenepeel, Hong Ma, Cherylene Plewa, Ki Jeong Lee, Angela Coxon, Paul E. Hughes, Pedro Beltran. HGF mediated resistance to BRAF inhibition in BRAF V600E mutant melanoma xenograft models. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3712. doi:10.1158/1538-7445.AM2014-3712

Anticancer activity of the type I insulin-like growth factor receptor antagonist, ganitumab, in combination with the death receptor 5 agonist, conatumumab

Agents targeting the insulin-like growth factor receptor type 1 (IGF1R) have shown antitumor activity. Based on the evidence for interaction between the IGF-1 and TRAIL pathways, we hypothesized that the combination of ganitumab (monoclonal antibody to IGF1R) with the pro-apoptotic death receptor 5 agonist, conatumumab, might increase antitumor response. Ganitumab and conatumumab were tested in combination in a Colo-205 xenograft model. Part 1 of the clinical study was a phase Ib program of three doses of conatumumab (1, 3, 15 mg/kg) in combination with 18 mg/kg ganitumab to determine the maximum tolerated dose (MTD) in patients with advanced solid tumors. Part 2 was conducted in six cohorts with advanced non-small cell lung cancer (squamous or non-squamous histology), colorectal cancer, sarcoma, pancreatic cancer, or ovarian cancer, treated at the recommended doses of the combination. The combination was significantly more active in the Colo-205 xenograft model than either single agent alone (p < 0.0015). In part 1 of the clinical study, no dose-limiting toxicities were observed and the MTD of conatumumab was 15 mg/kg in combination with 18 mg/kg ganitumab. In part 2, 78 patients were treated and there were no objective responses but 28 patients (36 %) had stable disease (median 46 days, range 0-261). The combination was well-tolerated with no new toxicities. In conclusion, the combination of ganitumab and conatumumab was well-tolerated but had no objective responses in the population tested. The successful future application of this combination of antitumor mechanisms may rely on the identification of predictive biomarkers.

Cell density-dependent regulation of mdr-1 gene expression in murine colon cancer cells

We studied the regulation of mdr-1 and P-glycoprotein in sparse and confluent cultures of murine CT-26 colon carcinoma cells. The expression level of mdr-1 mRNA transcripts (analyzed by Northern blot and in situ hybridization) and P-glycoprotein (analyzed by flow cytometry) inversely correlated with cell density. The modulation of mdr gene expression in sparse and confluent cells was not related to cell division, nutrient depletion, inhibition of protein synthesis, gap junction status, extracellular ATP, or the presence of various extracellular matrixes, but may be related to cell-density and cell-contact mediated changes in phosphatase activity. The confluence-mediated downmodulation of mdr-1 increased the chemosensitivity of the cells to several anticancer drugs commonly associated with an in vitro MDR phenotype by increasing the intracellular accumulation of the drugs. These data may explain some of the discrepancies in results obtained when analyzing mdr gene expression in tumors growing in vivo or in vitro, and why mdi expression in tumors is localized to the periphery of the lesions.

Novel Phases in the V-P-O Catalytic System from Oxovanadium Hydrogenphosphate Precursors

Several biphasic VOP04/(VO)2P2O7 redox partners seem to be active in the catalytic cycles involved in the mild oxidation of simple hydrocarbons to maleic anhydride. The present X-ray time resolved thermal-diffractometric study reveals the existence of a new anhydrous variety of the oxidized form, ω-VOPO4, which may appear as an intermediate in the formation of the well known β-VOPO4. This new phase only remains well crystallized at relatively high temperatures, and when it is allowed to cool down in wet air VOPO4·2H2O results. In turn, another well defined phase, VOPO4·1.58H2O, can be recognized in the course of the hydration process.

Abstract LB-429: Synergistic effects of low-fat diet combined with IGF-I receptor blockade on 22RV1 prostate cancer xenografts

Introduction: IGF-I receptor (IGF-1R) blockade has previously been shown to slow prostate cancer xenograft growth. Dietary fat reduction also inhibits xenograft growth, possibly by modulation of the IGF axis. We hypothesized that a low-fat (LF) diet combined with IGF-I receptor blockade would cause additive retardation of prostate cancer growth and offset the possible untoward metabolic effects of IGF-1R antibody therapy.

Methods: Fifty severe combined immunodeficient mice were injected subcutaneously with 22RV1 cells (suppressible with IGF-1R blockade in vitro) and were randomized to four groups: 1) high-fat (HF) diet with intraperitoneal saline, 2) high-fat diet with intraperitoneal IGF-I receptor blocking antibody from Amgen: AMG479, (HFAb), 3) low-fat diet with intraperitoneal saline (LF), 4) low-fat diet with intraperitoneal AMG479, (LFAb). Treatment with either antibody or saline was initiated 10 days after tumor injection and given twice weekly, tumors were measured serially. The animals were euthanized at 19 days of treatment. Tumors were then weighed and stained for Ki67, TUNEL, and CD31. Serum levels of insulin, resistin, murine IGF-I, murine IGFBP-3, and TNF-alpha were measured.

Results: Mean tumor weights were significantly lower (by ∼ 40%) in the HFAb and LFAb group relative to the HF group. There was no difference in mean tumor weight between the HFAb and LFAb groups. Ki67 expression (% positive cells) was significantly decreased in the LFAb group compared to the HFAb group (62 + 29 vs. 94 + 4.3, p&lt;0.001). IGF-1R antibody caused a significant increase in serum insulin levels compared to the LF and HF group, but combining the LF diet with the IGF-1R antibody significantly reduced serum insulin levels by 40% relative to the HFAb group. Likewise, combining a LF diet with the IGF-1R antibody also reduced serum TNF-alpha levels relative to the HF group.

Conclusion: IGF-1R antibody therapy inhibited xenograft growth in mice on HF and LF diets. Whereas combining a LF diet with IGF-1R antibody did not have additive growth inhibitory effects on tumor size, there was evidence of decreased tumor cell proliferation, reduced serum insulin levels and reduced pro-inflammatory cytokine levels. Further pre-clinical and clinical trials are warranted to evaluate the role of dietary interventions to enhance anti-tumor effects and offset the metabolic consequences of IGF-1R antibody therapy.

Aknowledgements: This work was supported by the NCI grant # P50CA92131 and “The Ruby Family Foundation”.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-429.

Economic evaluation of the TAX 324 trial comparing docetaxel plus cisplatin and 5-fluorouracil (TPF) versus standard treatment with cisplatin and 5-fluorouracil (PF) as induction chemotherapy followed by concurrent chemoradiation therapy in locally advanced squamous cell carcinoma of the head and neck (SCCHN)

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Background: The TAX 324 phase III trial showed that induction chemotherapy with TPF followed by chemoradiotherapy improves survival and time to progression in patients with locally advanced SCCHN compared with PF [Posner MR, et al. ASCO 2006]. A Markov state-transition model was developed to estimate the cost-effectiveness of TPF. Methods: The Markov model includes four health states (based on WHO criteria for measuring objective response): stable, responsive, progressive disease, and death. TAX 324 efficacy data were used to derive transition probabilities between health states. Adverse event rates were also derived from TAX 324. Data for resource utilization and costs from a UK perspective were derived from the literature and clinician inputs from an advisory board. The global score of the Health Related Quality of Life Questionnaire Core-30 (QLQ-C30) was mapped to the EQ-5D in order to derive utilities and quality adjusted life years (QALYs). Results: A patient in the TPF arm survived longer versus PF (5.4 vs. 2.7 years). Comparison of TPF vs. PF resulted in an incremental gain of 2.7 life years and 2.1 QALYs. The incremental discounted costs/QALY gained for TPF vs. PF was £1,988/QALY, which is below the £20,000 cost-effectiveness threshold suggested by NICE as a guide to the acceptability of a technology. At this threshold, there is a 96.1% probability that TPF is cost-effective compared with PF. Conclusion: Docetaxel, when given as induction chemotherapy followed by concurrent chemoradiotherapy in combination with cisplatin and 5-fluorouracil (TPF), leads to a substantial increase in life expectancy, and is cost-effective compared with PF for locally advanced SCCHN.

No significant financial relationships to disclose.

Potent induction of human colon cancer cell uptake of chemotherapeutic drugs by N-myristoylated protein kinase C-alpha (PKC-alpha) pseudosubstrate peptides through a P-glycoprotein-independent mechanism

Phorbol ester protein kinase C (PKC) activators and PKC isozyme over-expression have been shown to significantly reduce intracellular accumulation of chemotherapeutic drugs, in association with the induction of multidrug resistance (MDR) in drug-sensitive cancer cells and enhancement of drug resistance in MDR cancer cells. These observations constitute solid evidence that PKC plays a significant role in the MDR phenotype of cancer cells. PKC-catalyzed phosphorylation of the drug-efflux pump P-glycoprotein was recently ruled out as a contributing factor in MDR. At present, the sole drug transport-related event that has been identified as a component of the role of PKC in MDR is PKC-induced expression of the P-glycoprotein-encoding gene mdr1. The objective of this study was to test the hypothesis that PKC can modulate the uptake of chemotherapeutic drugs in cancer cells independently of P-glycoprotein. We analyzed the effects of selective PKC activators/inhibitors on the uptake of radiolabelled cytotoxic drugs by cultured human colon cancer cells that lacked P-glycoprotein activity and did not express the drug efflux pump at the level of message (mdr1) or protein. We found that the selective PKC activator 12-O-tetradecanoylphorbol-13-acetate (TPA) significantly reduced uptake of [14C] Adriamycin and [3H] vincristine in human colon cancer cells devoid of P-glycoprotein activity, and that PKC-inhibitory N-myristoylated PKC-alpha pseudosubstrate synthetic peptides potently and selectively induced uptake of the cytotoxic drugs in the phorbol ester-treated and non-treated colon cancer cells. TPA treatment of the cells did not induce expression of either P-glycoprotein or its message mdr1. In contrast with [14C]Adriamycin and [3H] vincristine uptake, [3H] 5-fluorouracil uptake by the cells was unaffected by TPA and reduced by the PKC-inhibitory peptides. These results indicate that PKC activation can significantly reduce the uptake of multiple cytotoxic drugs by cancer cells independently of P-glycoprotein, and that N-myristoylated PKC-alpha pseudosubstrate peptides potently and selectively induce uptake of multiple cytotoxic drugs in cultured human colon cancer cells by a novel mechanism that does not involve P-glycoprotein and may involve PKC isozyme inhibition. Thus, N-myristoylated PKC-alpha pseudosubstrate peptides may offer a basis for the development of agents that reverse intrinsic drug resistance in human colon cancer.

Circumvention of multidrug-resistance in murine fibrosarcoma and colon-carcinoma cells by treatment with the alpha-adrenoceptor antagonist furobenzazepine

The purpose of this study was to determine whether agonists and antagonists of alpha-adrenoceptors that affect calcium fluxes and protein kinase C signal transduction alter the chemosensitivity of cancer cells that exhibit multidrug resistance (MDR). The effects of nine alpha-adrenoceptor antagonists or antagonists on the in vitro chemosensitivity of the UV-2237 murine fibrosarcoma and its doxorubicin-selected MDR variants (UV-2237-R1 and UV-2237-R10) were examined. Noncytotoxic concentrations of the alpha-adrenoceptor antagonist furobenzazepine enhanced the antitumor activity of doxorubicin, actinomycin D, vinblastine and vincristine, but not 5-fluorouracil. Similar effects of furobenzazepine were also observed in recently established doxorubicin-resistant MDR variants of the CT-26 murine colon carcinoma. The chemosensitizing effect of furobenzazepine was associated with an increase in intracellular accumulation of anticancer drugs. Furobenzazepine did not compete with [H-3]azidopine for photoaffinity labeling of P-glycoprotein, but it did produce a transient 30% reduction of P-glycoprotein in the MDR cells. These data indicate that furobenzazepine can reverse a P-glycoprotein-mediated experimental MDR phenotype.

Salmonella reference collection B (SARB): strains of 37 serovars of subspecies I

A reference collection of 72 strains representing 37 serovars of Salmonella subspecies I has been established for use in research on genetic and phenotypic variation in natural populations. Included are isolates of the host-adapted serovars S. choleraesuis, S. dublin, S. gallinarum, S. paratyphi A, S. paratyphi B, S. paratyphi C, S. pullorum, S. sendai, S. typhi and S. typhisuis, as well as strains of S. enteritidis, S. typhimurium, and other commonly recovered serovars with broad host ranges. The isolates were characterized by enzyme electrophoresis for allelic variation in 25 chromosomal genes and represent 71 distinctive multilocus genotypes (electrophoretic types or ETs). Genetic relationships among the ETs are indicated in an evolutionary tree constructed by the neighbour-joining method from a matrix of Nei's standard genetic distance.

Molecular evolutionary genetics of the cattle-adapted serovar Salmonella dublin

An electrophoretic analysis of allelic variation at 24 enzyme loci among 170 isolates of the serovar Salmonella dublin (serotype 1,9,12[Vi]:g,p:-) identified three electrophoretic types (Du 1, Du 3, and Du 4), marking three closely related clones, one of which (Du 1) is globally distributed and was represented by 95% of the randomly selected isolates. All but 1 of 114 nonmotile isolates of serotype 1,9,12:-:- recovered from cattle and swine in the United States were genotypically Du 1. The virulence capsular polysaccharide (Vi antigen) is confined to clone Du 3, which apparently is limited in distribution to France and Great Britain. For all 29 isolates of Du 3, positive signals were detected when genomic DNA was hybridized with a probe specific for the ViaB region, which contains the structurally determinant genes for the Vi antigen; and 23 of these isolates had been serologically typed as Vi positive. In contrast, all 30 isolates of Du 1 tested with the ViaB probe were negative. These findings strongly suggest that the ViaB genes were recently acquired by S. dublin via horizontal transfer and additive recombination. The clones of S. dublin are closely similar to the globally predominant clone (En 1) of Salmonella enteritidis (serotype 1,9,12:g,m:-) in both multilocus enzyme genotype and nucleotide sequence of the fliC gene encoding phase 1 flagellin. Comparative sequencing of fliC has revealed the molecular genetic basis for expression of the p and m flagellar epitopes by which these serovars are distinguished in the Kauffmann-White serological scheme of classification.

Reference collection of strains of the Salmonella typhimurium complex from natural populations

A collection of 72 reference strains of the Salmonella typhimurium complex of clones recovered from a variety of hosts and environmental sources in diverse geographic locations has been established for use in studies of variation in natural populations. Included are strains of the serovars S. typhimurium, S. saintpaul, S. heidelberg, S. paratyphi B (including variety java) and S. muenchen. The strains, which have been characterized by enzyme electrophoresis for allelic variation in 24 chromosomal structural genes and represent 48 distinctive multilocus genotypes (electrophoretic types or ETs), exemplify the full range of genotypic variation in the S. typhimurium complex. Evolutionary genetic relationships among the ETs are indicated in a phylogenetic tree generated by the neighbour-joining method from a matrix of Nei's standard genetic distance.

Evolutionary genetic relationships of clones of Salmonella serovars that cause human typhoid and other enteric fevers

Multilocus enzyme electrophoresis was employed to measure chromosomal genotypic diversity and evolutionary relationships among 761 isolates of the serovars Salmonella typhi, S. paratyphi A, S. paratyphi B, S. paratyphi C, and S. sendai, which are human-adapted agents of enteric fever, and S. miami and S. java, which are serotypically similar to S. sendai and S. paratyphi B, respectively, but cause gastroenteritis in both humans and animals. To determine the phylogenetic positions of the clones of these forms within the context of the salmonellae of subspecies I, comparative data for 22 other common serovars were utilized. Except for S. paratyphi A and S. sendai, the analysis revealed no close phylogenetic relationships among clones of different human-adapted serovars, which implies convergence in host adaptation and virulence factors. Clones of S. miami are not allied with those of S. sendai or S. paratyphi A, being, instead, closely related to strains of S. panama. Clones of S. paratyphi B and S. java belong to a large phylogenetic complex that includes clones of S. typhimurium, S. heidelberg, S. saintpaul, and S. muenchen. Most strains of S. paratyphi B belong to a globally distributed clone that is highly polymorphic in biotype, bacteriophage type, and several other characters, whereas strains of S. java represent seven diverse lineages. The flagellar monophasic forms of S. java are genotypically more similar to clones of S. typhimurium than to other clones of S. java or S. paratyphi B. Clones of S. paratyphi C are related to those of S. choleraesuis. DNA probing with a segment of the viaB region specific for the Vi capsular antigen genes indicated that the frequent failure of isolates of S. paratyphi C to express Vi antigen is almost entirely attributable to regulatory processes rather than to an absence of the structural determinant genes themselves. Two clones of S. typhisuis are related to those of S. choleraesuis and S. paratyphi C, but a third clone is not. Although the clones of S. decatur and S. choleraesuis are serologically and biochemically similar, they are genotypically very distinct. Two clones of S. typhi were distinguished, one globally distributed and another apparently confined to Africa; both clones are distantly related to those of all other serovars studied.

Genetic population structure, clonal phylogeny, and pathogenicity of Salmonella paratyphi B

Genetic diversity and relationships among 123 strains of Salmonella paratyphi B (serotype 1,4,[5],12:b:[1,2]) were estimated from an assessment of electrophoretically demonstrable allelic variation at 24 chromosomal enzyme gene loci. Fourteen electrophoretic types, marking clones, were distinguished, the phylogeny of the clonal lineages was reconstructed, and biotype and other phenotypic characters were mapped onto this structure. Most d-tartrate-negative strains are members of an abundant, globally distributed clone (Pb 1) that is polymorphic for many biotype characters (including d-tartrate utilization), bacteriophage type, rRNA pattern, and colicin M and phage ES18 sensitivity. This clone is largely responsible for S. paratyphi B enteric fever in humans. In contrast, d-tartrate-positive strains (formerly known as S. java) occurred in all seven of the clonal lineages identified by population genetic analysis, although most d-tartrate-positive isolates belong to only two clones (Pb 3 and Pb 4), which vary in frequency geographically. Monophasic strains represent four closely related clones forming a distinctive phylogenetic lineage. The Kauffmann hypothesis of convergence in serotype among distantly related cell lineages through recombination (via phage transduction or other means) may account for the considerable genotypic diversity among clones of S. paratyphi B. Pb 4, Pb 6, and Pb 7 are more closely allied with clones of S. typhimurium and S. saintpaul than with other clones of S. paratyphi B. Sensitivity or resistance to colicin M and phage ES18 and the electrophoretic pattern of the rRNA, which were incorporated into a recently proposed scheme for the identification of types of S. paratyphi B, individually or in combination fail to mark clones or other meaningful phylogenetic subdivisions.

Recombination of Salmonella phase 1 flagellin genes generates new serovars

To determine the evolutionary mechanisms generating serotypic diversity in Salmonella strains, we sequenced the central, antigen-determining part of the phase 1 flagellin gene (fliC) in strains of several serovars for which estimates of chromosomal genomic relatedness had been obtained by multilocus enzyme electrophoresis. The nucleotide sequence of this region was identical in several chromosomally divergent strains of Salmonella heidelberg (phase 1 antigen r) but differed by 19% from the corresponding and similarly invariant sequence in strains of the closely related serovar Salmonella typhimurium (phase 1 antigen i). Mutational drift of the sequence present in the common ancestor is unlikely to have generated the difference between the phase 1 flagellins of these two serovars, which we attribute instead to a recombination event. This interpretation is supported by evidence that Salmonella strains of very diverse chromosomal backgrounds but similar phase 1 antigens may have closely similar nucleotide sequences for this highly polymorphic region. We suggest that lateral transfer and recombination of phase 1 flagellin genes is a major evolutionary mechanism generating new Salmonella serovars.

Restriction fragment length polymorphisms among uropathogenic Escherichia coli isolates: pap-related sequences compared with rrn operons

Among the adhesin-encoding virulence operons associated with uropathogenic Escherichia coli, only pap (pyelonephritis-associated pilus)-related gene clusters typically exhibit variation in their structure and chromosomal copy number. To access further such variability, we compared pap restriction fragment length polymorphisms (RFLPs) with those detected among rRNA (rrn) operons, which encode an essential host function unrelated to virulence. To place such findings in a phylogenetic perspective, the E. coli isolates were also characterized by using multilocus enzyme electrophoresis. Variation in the rrn RFLP profiles correlated with evolutionary divergence resolved by multilocus enzyme electrophoresis; isolates with identical rrn profiles represented the same or closely related electrophoretic types. In contrast, such isolates frequently had different pap-related RFLPs, indicating that these genetic variations have developed recently relative to the changes associated with essential rrn operons or metabolic enzymes. Despite such fluctuations, two lines of evidence indicate conditions under which the pap-related RFLPs can be stably maintained. First, for each of 20 patients with urosepsis, both the primary urinary tract isolate and the concurrent blood isolate were identical. Second, although obtained from different patients, some isolates representing the same electrophoretic type also had identical pap-related RFLPs. Thus, the genotypic diversity of this virulence adhesin operon was not generated during the course of acute infection or during laboratory manipulations. Since fecal E. coli isolates frequently carry chromosomally encoded pap-related gene clusters, these findings suggest that the intra- and interchromosomal recombination events generating the polymorphisms associated with the pap-related sequences likely occur among the E. coli of the commensal reservoir.

Toward a population genetic analysis of Salmonella: genetic diversity and relationships among strains of serotypes S. choleraesuis, S. derby, S. dublin, S. enteritidis, S. heidelberg, S. infantis, S. newport, and S. typhimurium

Variation in the chromosomal genomes of 1527 isolates of eight common serotypes (O and H antigen profiles) of Salmonella was assessed by analysis of electrophoretically demonstrable allelic polymorphism at 23 metabolic enzyme loci. Seventy-one distinctive electrophoretic types, representing multilocus genotypes, were identified. A basically clonal population structure was indicated by the presence of strong linkage disequilibrium among enzyme loci, the association of each serotype with a relatively small number of multilocus enzyme genotypes, and the global distribution of certain genotypes. For each of six of the serotypes, 83-96% of isolates were members of a single clone. The occurrence of each of four serotypes (S. derby, S. enteritidis, S. infantis, and S. newport) in isolates of clones belonging to several evolutionary lineages, some of which are distantly related, suggests that the horizontal transfer and recombination of chromosomal genes mediating expression of cell-surface antigens has been a significant process in the evolution of the salmonellae. Two divergent clone clusters of S. derby differ in the relative frequency with which they cause disease in birds versus mammals, and two major lineages of S. newport differ in the frequency with which their clones are associated with disease in humans versus animals.

Coronary artery spasm appearing as syncope

A 56-year-old man had coronary artery spasm. The initial manifestation of the disease was syncope that occurred at night. Coronary artery spasm was documented by Holter recording and cardiac catheterization. The patient was effectively treated with nitrates and calcium-blocking agents.