Long-term survival with first-line nivolumab plus ipilimumab in patients with advanced non-small-cell lung cancer: a pooled analysis.

BACKGROUND: First-line nivolumab plus ipilimumab prolongs survival versus chemotherapy in advanced non-small-cell lung cancer (NSCLC). We further characterized clinical benefit with this regimen in a large pooled patient population and assessed the effect of response on survival. PATIENTS AND METHODS: Data were pooled from four studies of first-line nivolumab plus ipilimumab in advanced NSCLC (CheckMate 227 Part 1, 817 cohort A, 568 Part 1, and 012). Overall survival (OS), progression-free survival (PFS), objective response rate, duration of response, and safety were assessed. Landmark analyses of OS by response status at 6 months and by tumor burden reduction in responders to nivolumab plus ipilimumab were also assessed. RESULTS: In the pooled population (N = 1332) with a minimum follow-up of 29.1-58.9 months, median OS was 18.6 months, with a 3-year OS rate of 35%; median PFS was 5.4 months (3-year PFS rate, 17%). Objective response rate was 36%; median duration of response was 23.7 months, with 38% of responders having an ongoing response at 3 years. In patients with tumor programmed death-ligand 1 (PD-L1) <1%, ≥1%, 1%-49%, or ≥50%, 3-year OS rates were 30%, 38%, 30%, and 48%. Three-year OS rates were 30% and 38% in patients with squamous or non-squamous histology. Efficacy outcomes in patients aged ≥75 years were similar to the overall pooled population (median OS, 20.1 months; 3-year OS rate, 34%). In the pooled population, responders to nivolumab plus ipilimumab at 6 months had longer post-landmark OS than those with stable or progressive disease; 3-year OS rates were 66%, 22%, and 14%, respectively. Greater depth of response was associated with prolonged survival; in patients with tumor burden reduction ≥80%, 50% to <80%, or 30% to <50%, 3-year OS rates were 85%, 72%, and 44%, respectively. No new safety signals were identified in the pooled population. CONCLUSION: Long-term survival benefit and durable response with nivolumab plus ipilimumab in this large patient population further support this first-line treatment option for advanced NSCLC.

Safety and efficacy of pralsetinib in RET fusion-positive non-small-cell lung cancer including as first-line therapy: update from the ARROW trial.

BACKGROUND: RET fusions are present in 1%-2% of non-small-cell lung cancer (NSCLC). Pralsetinib, a highly potent, oral, central nervous system-penetrant, selective RET inhibitor, previously demonstrated clinical activity in patients with RET fusion-positive NSCLC in the phase I/II ARROW study, including among treatment-naive patients. We report an updated analysis from the ARROW study. PATIENTS AND METHODS: ARROW is a multi-cohort, open-label, phase I/II study. Eligible patients were ≥18 years of age with locally advanced or metastatic solid tumours and an Eastern Cooperative Oncology Group performance status of 0-2 (later 0-1). Patients initiated pralsetinib at the recommended phase II dose of 400 mg once daily until disease progression, intolerance, consent withdrawal, or investigator's decision. The co-primary endpoints (phase II) were overall response rate (ORR) by blinded independent central review and safety. RESULTS: Between 17 March 2017 and 6 November 2020 (data cut-off), 281 patients with RET fusion-positive NSCLC were enrolled. The ORR was 72% [54/75; 95% confidence interval (CI) 60% to 82%] for treatment-naive patients and 59% (80/136; 95% CI 50% to 67%) for patients with prior platinum-based chemotherapy (enrolment cut-off for efficacy analysis: 22 May 2020); median duration of response was not reached for treatment-naive patients and 22.3 months for prior platinum-based chemotherapy patients. Tumour shrinkage was observed in all treatment-naive patients and in 97% of patients with prior platinum-based chemotherapy; median progression-free survival was 13.0 and 16.5 months, respectively. In patients with measurable intracranial metastases, the intracranial response rate was 70% (7/10; 95% CI 35% to 93%); all had received prior systemic treatment. In treatment-naive patients with RET fusion-positive NSCLC who initiated pralsetinib by the data cut-off (n = 116), the most common grade 3-4 treatment-related adverse events (TRAEs) were neutropenia (18%), hypertension (10%), increased blood creatine phosphokinase (9%), and lymphopenia (9%). Overall, 7% (20/281) discontinued due to TRAEs. CONCLUSIONS: Pralsetinib treatment produced robust efficacy and was generally well tolerated in treatment-naive patients with advanced RET fusion-positive NSCLC. Results from the confirmatory phase III AcceleRET Lung study (NCT04222972) of pralsetinib versus standard of care in the first-line setting are pending.

Safety and activity of alectinib plus bevacizumab in patients with advanced ALK-rearranged non-small-cell lung cancer: a phase I/II study.

BACKGROUND: Alectinib, a second-generation anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitor (TKI), is highly effective in advanced ALK-rearranged non-small-cell lung cancer and represents a standard first-line therapy. New strategies are needed, however, to delay resistance. We conducted a phase I/II study to assess the safety and efficacy of combining alectinib with bevacizumab, a monoclonal antibody against vascular endothelial growth factor. PATIENTS AND METHODS: Patients with advanced ALK-rearranged non-squamous non-small-cell lung cancer were enrolled. The phase I portion employed a dose de-escalation strategy with alectinib and bevacizumab starting at the individual standard doses. The primary objective was to determine the recommended phase II dose (RP2D). In phase II, the primary objective was to evaluate the safety of the combination at the RP2D; the secondary objective was to determine extracranial and intracranial efficacy. RESULTS: Eleven patients were enrolled between September 2015 and February 2020. Most patients (82%) had baseline brain metastases. Six patients (55%) were treatment-naive; five (46%) had received prior ALK TKIs (crizotinib, n = 3; ceritinib, n = 1; crizotinib then brigatinib, n = 1). No dose-limiting toxicities occurred. RP2D was determined as alectinib 600 mg orally twice daily plus bevacizumab 15 mg/kg intravenously every 3 weeks. Three patients experienced grade 3 treatment-related adverse events: pneumonitis related to alectinib, proteinuria related to bevacizumab, and hypertension related to bevacizumab. Treatment-related intracranial hemorrhage was not observed. Six (100%) of six treatment-naive patients and three (60%) of five ALK TKI-pretreated patients had objective responses; median progression-free survival was not reached (95% confidence interval, 9.0 months-not reached) and 9.5 months (95% confidence interval, 4.3 months-not reached), respectively. Intracranial responses occurred in four (100%) of four treatment-naive and three (60%) of five TKI-pretreated patients with baseline brain metastases. The study was stopped prematurely because of slow accrual. CONCLUSIONS: Alectinib plus bevacizumab was well tolerated without unanticipated toxicities or dose-limiting toxicities.

Clinical definition of acquired resistance to immunotherapy in patients with metastatic non-small-cell lung cancer.

Acquired resistance (AR) to programmed cell death protein 1/programmed death-ligand 1 [PD-(L)1] blockade is frequent in non-small-cell lung cancer (NSCLC), occurring in a majority of initial responders. Patients with AR may have unique properties of persistent antitumor immunity that could be re-harnessed by investigational immunotherapies. The absence of a consistent clinical definition of AR to PD-(L)1 blockade and lack of uniform criteria for ensuing enrollment in clinical trials remains a major barrier to progress; such clinical definitions have advanced biologic and therapeutic discovery. We examine the considerations and potential controversies in developing a patient-level definition of AR in NSCLC treated with PD-(L)1 blockade. Taking into account the specifics of NSCLC biology and corresponding treatment strategies, we propose a practical, clinical definition of AR to PD-(L)1 blockade for use in clinical reports and prospective clinical trials. Patients should meet the following criteria: received treatment that includes PD-(L)1 blockade; experienced objective response on PD-(L)1 blockade (inclusion of a subset of stable disease will require future investigation); have progressive disease occurring within 6 months of last anti-PD-(L)1 antibody treatment or rechallenge with anti-PD-(L)1 antibody in patients not exposed to anti-PD-(L)1 in 6 months.

ESMO recommendations on the standard methods to detect RET fusions and mutations in daily practice and clinical research.

Aberrant activation of RET is a critical driver of growth and proliferation in diverse solid tumours. Multikinase inhibitors (MKIs) showing anti-RET activities have been tested in RET-altered tumours with variable results. The low target specificity with consequent increase in side-effects and off-target toxicities resulting in dose reduction and drug discontinuation are some of the major issues with MKIs. To overcome these issues, new selective RET inhibitors such as pralsetinib (BLU-667) and selpercatinib (LOXO-292) have been developed in clinical trials, with selpercatinib recently approved by the Food and Drug Administration (FDA). The results of these trials showed marked and durable antitumour activity and manageable toxicity profiles in patients with RET-altered tumours. The European Society for Medical Oncology (ESMO) Translational Research and Precision Medicine Working Group (TR and PM WG) launched a collaborative project to review the available methods for the detection of RET gene alterations, their potential applications and strategies for the implementation of a rational approach for the detection of RET fusion genes and mutations in human malignancies. We present here recommendations for the routine clinical detection of targetable RET rearrangements and mutations.

Mechanisms of resistance to selective RET tyrosine kinase inhibitors in RET fusion-positive non-small-cell lung cancer.

BACKGROUND: Rearranged during transfection (RET) gene fusions are a validated target in non-small-cell lung cancer (NSCLC). RET-selective inhibitors selpercatinib (LOXO-292) and pralsetinib (BLU-667) recently demonstrated favorable antitumor activity and safety profiles in advanced RET fusion-positive NSCLC, and both have received approval by the US Food and Drug Administration for this indication. Insights into mechanisms of resistance to selective RET inhibitors remain limited. PATIENTS AND METHODS: This study was performed at five institutions. Tissue and/or cell-free DNA was obtained from patients with RET fusion-positive NSCLC after treatment with selpercatinib or pralsetinib and assessed by next-generation sequencing (NGS) or MET FISH. RESULTS: We analyzed a total of 23 post-treatment tissue and/or plasma biopsies from 18 RET fusion-positive patients who received an RET-selective inhibitor (selpercatinib, n = 10; pralsetinib, n = 7; pralsetinib followed by selpercatinib, n = 1, with biopsy after each inhibitor). Three cases had paired tissue and plasma samples, of which one also had two serial resistant tissue specimens. The median progression-free survival on RET inhibitors was 6.3 months [95% confidence interval 3.6-10.8 months]. Acquired RET mutations were identified in two cases (10%), both affecting the RET G810 residue in the kinase solvent front. Three resistant cases (15%) harbored acquired MET amplification without concurrent RET resistance mutations, and one specimen had acquired KRAS amplification. No other canonical driver alterations were identified by NGS. Among 16 resistant tumor specimens, none had evidence of squamous or small-cell histologic transformation. CONCLUSIONS: RET solvent front mutations are a recurrent mechanism of RET inhibitor resistance, although they occurred at a relatively low frequency. The majority of resistance to selective RET inhibition may be driven by RET-independent resistance such as acquired MET or KRAS amplification. Next-generation RET inhibitors with potency against RET resistance mutations and combination strategies are needed to effectively overcome resistance in these patients.

Clinical activity of programmed cell death 1 (PD-1) blockade in never, light, and heavy smokers with non-small-cell lung cancer and PD-L1 expression ≥50.

BACKGROUND: Immune checkpoint inhibitors (ICIs) are standard therapies for patients with advanced non-small-cell lung cancer (NSCLC) and a programmed death-ligand 1 (PD-L1) tumor proportion score (TPS) ≥50%. Tumor mutation burden (TMB) also predicts response to ICIs but is often not available in real time for decision making in the first-line setting. Smoking exposure can be a proxy for TMB in NSCLC. The impact of smoking status on efficacy of PD-1 blockade in NSCLC patients with PD-L1 TPS ≥50% has not been well defined. PATIENTS AND METHODS: To investigate the relationship between smoking and activity of ICIs in NSCLC, we retrospectively studied 315 patients with NSCLC and PD-L1 TPS ≥50% at five USA academic medical centers. Objective response rates (ORRs), progression-free survival (PFS), and duration of response (DOR) were compared between never (<100 lifetime cigarettes), light (≤10 pack-years), and heavy (>10 pack-years) smokers. A subset of patients underwent next-generation sequencing to estimate TMB. RESULTS: We identified 36 (11%) never, 42 (13%) light, and 237 (75%) heavy smokers with NSCLC and PD-L1 TPS ≥50% treated with ICIs. Objective responses were observed in 27%, 40%, and 40% of never, light, and heavy smokers, respectively (P = 0.180 never versus heavy; P = 1.000 light versus heavy). Median PFS and median DOR were numerically shorter in never and light smokers compared with heavy smokers (PFS 3.0 versus 4.0 versus 5.4 months; median DOR 6.9 versus 10.8 versus 17.8 months), but were not statistically different [PFS: hazard ratio (HR) 1.37, P = 0.135 and HR 1.24, P = 0.272; DOR: HR 1.92, P = 0.217 and HR 1.79, P = 0.141]. CONCLUSIONS: PD-(L)1 inhibitors are associated with antitumor activity in NSCLC with PD-L1 TPS ≥50% regardless of smoking status. Nevertheless, there is a signal of potentially decreased durability among never and light smokers that should be further evaluated. Distinct immunobiologic features may affect initial response versus durability of antitumor immunity to programmed cell death 1 (PD-1) blockade.

Outcomes to first-line pembrolizumab in patients with non-small-cell lung cancer and very high PD-L1 expression.

BACKGROUND: In non-small-cell lung cancers with programmed death-ligand 1 (PD-L1) expression on ≥50% of tumor cells, first-line treatment with the PD-1 inhibitor pembrolizumab improves survival compared with platinum-doublet chemotherapy. Whether higher PD-L1 levels within the expression range of 50%-100% predict for even greater benefit to pembrolizumab is currently unknown. PATIENTS AND METHODS: In this multicenter retrospective analysis, we analyzed the impact of PD-L1 expression levels on the overall response rate (ORR), median progression-free survival (mPFS), and median overall survival (mOS) in patients who received commercial pembrolizumab as first-line treatment of non-small-cell lung cancer (NSCLC) with a PD-L1 expression of ≥50% and negative for genomic alterations in the EGFR and ALK genes . RESULTS: Among 187 patients included in this analysis, the ORR was 44.4% [95% confidence interval (CI) 37.1% to 51.8%], the mPFS was 6.5 months (95% CI 4.5-8.5), and the mOS was not reached. The median PD-L1 expression level among patients who experienced a response to pembrolizumab was significantly higher than among patients with stable or progressive disease (90% versus 75%, P < 0.001). Compared with patients with PD-L1 expression of 50%-89% (N = 107), patients with an expression level of 90%-100% (N = 80) had a significantly higher ORR (60.0% versus 32.7%, P < 0.001), a significantly longer mPFS [14.5 versus 4.1 months, hazard ratio (HR) 0.50 (95% CI 0.33-0.74), P < 0.01], and a significantly longer mOS [not reached versus 15.9 months, HR 0.39 (95% CI 0.21-0.70), P = 0.002]. CONCLUSION: Among patients with NSCLC and PD-L1 expression of ≥50% treated with first-line pembrolizumab, clinical outcomes are significantly improved in NSCLCs with a PD-L1 expression of ≥90%. These findings have implications for treatment selection as well as for clinical trial interpretation and design.

Phase Ib study of atezolizumab combined with cobimetinib in patients with solid tumors.

BACKGROUND: Preclinical evidence suggests that MEK inhibition promotes accumulation and survival of intratumoral tumor-specific T cells and can synergize with immune checkpoint inhibition. We investigated the safety and clinical activity of combining a MEK inhibitor, cobimetinib, and a programmed cell death 1 ligand 1 (PD-L1) inhibitor, atezolizumab, in patients with solid tumors. PATIENTS AND METHODS: This phase I/Ib study treated PD-L1/PD-1-naive patients with solid tumors in a dose-escalation stage and then in multiple, indication-specific dose-expansion cohorts. In most patients, cobimetinib was dosed once daily orally for 21 days on, 7 days off. Atezolizumab was dosed at 800 mg intravenously every 2 weeks. The primary objectives were safety and tolerability. Secondary end points included objective response rate, progression-free survival, and overall survival. RESULTS: Between 27 December 2013 and 9 May 2016, 152 patients were enrolled. As of 4 September 2017, 150 patients received ≥1 dose of atezolizumab, including 14 in the dose-escalation cohorts and 136 in the dose-expansion cohorts. Patients had metastatic colorectal cancer (mCRC; n = 84), melanoma (n = 22), non-small-cell lung cancer (NSCLC; n = 28), and other solid tumors (n = 16). The most common all-grade treatment-related adverse events (AEs) were diarrhea (67%), rash (48%), and fatigue (40%), similar to those with single-agent cobimetinib and atezolizumab. One (<1%) treatment-related grade 5 AE occurred (sepsis). Forty-five (30%) and 23 patients (15%) had AEs that led to discontinuation of cobimetinib and atezolizumab, respectively. Confirmed responses were observed in 7 of 84 patients (8%) with mCRC (6 responders were microsatellite low/stable, 1 was microsatellite instable), 9 of 22 patients (41%) with melanoma, and 5 of 28 patients (18%) with NSCLC. Clinical activity was independent of KRAS/BRAF status across diseases. CONCLUSIONS: Atezolizumab plus cobimetinib had manageable safety and clinical activity irrespective of KRAS/BRAF status. Although potential synergistic activity was seen in mCRC, this was not confirmed in a subsequent phase III study. CLINICALTRIALS.GOV IDENTIFIER: NCT01988896 (the investigators in the NCT01988896 study are listed in the supplementary Appendix, available at Annals of Oncology online).

Activity of the Hsp90 inhibitor luminespib among non-small-cell lung cancers harboring EGFR exon 20 insertions.

Background: There are currently no approved targeted therapies for non-small-cell lung cancer (NSCLC) patients with EGFR exon 20 insertions (ins20), a subgroup of EGFR mutations that are generally refractory to first/second generation EGFR inhibitors. We report the final results of a phase II trial evaluating the activity of the Hsp90 inhibitor luminespib (AUY922) in NSCLC patients with EGFR ins20. Patients and methods: Twenty-nine patients with stage IV NSCLC with EGFR ins20 identified on local testing and at least one prior therapy were enrolled on the trial between August 2013 and October 2016. The primary end point was objective response rate (ORR), with a pre-determined target rate of effectiveness [defined as the rate of partial response (PR) plus stable disease (SD) lasting ≥3 months] of 20%. Secondary end points were PFS, overall survival (OS), safety and response by EGFR ins20 subtype. Results: Among the 29 patients (18 females, median age 60 years) the ORR was 17%, median progression-free survival was 2.9 months (95% CI 1.4-5.6) and median OS (mOS) was 13 months (95% CI 4.9-19.5). The results exceeded the pre-determined target rate of effectiveness with 11/29 (38%) patients having a PR or an SD ≥3 months. The most common luminespib-related toxicities were diarrhea (83%), visual changes (76%) and fatigue (45%). All study treatment was stopped on 28 February 2017 due to dissolution of study drug availability; 3 patients were on treatment at study termination. Conclusion: The study met its primary end point, suggesting that luminespib may be an active therapy for advanced NSCLC patients with EGFR ins20. Luminespib is generally well-tolerated, though reversible low-grade ocular toxicity is common. Further study of luminespib and other hsp90 inhibitors in this population is warranted. Study registration (ClinicalTrials.gov): NCT01854034.

Nivolumab versus docetaxel in previously treated advanced non-small-cell lung cancer (CheckMate 017 and CheckMate 057): 3-year update and outcomes in patients with liver metastases.

Background: Long-term data with immune checkpoint inhibitors in non-small-cell lung cancer (NSCLC) are limited. Two phase III trials demonstrated improved overall survival (OS) and a favorable safety profile with the anti-programmed death-1 antibody nivolumab versus docetaxel in patients with previously treated advanced squamous (CheckMate 017) and nonsquamous (CheckMate 057) NSCLC. We report results from ≥3 years' follow-up, including subgroup analyses of patients with liver metastases, who historically have poorer prognosis among patients with NSCLC. Patients and methods: Patients were randomized 1 : 1 to nivolumab (3 mg/kg every 2 weeks) or docetaxel (75 mg/m2 every 3 weeks) until progression or discontinuation. The primary end point of each study was OS. Patients with baseline liver metastases were pooled across studies by treatment for subgroup analyses. Results: After 40.3 months' minimum follow-up in CheckMate 017 and 057, nivolumab continued to show an OS benefit versus docetaxel: estimated 3-year OS rates were 17% [95% confidence interval (CI), 14% to 21%] versus 8% (95% CI, 6% to 11%) in the pooled population with squamous or nonsquamous NSCLC. Nivolumab was generally well tolerated, with no new safety concerns identified. Of 854 randomized patients across both studies, 193 had baseline liver metastases. Nivolumab resulted in improved OS compared with docetaxel in patients with liver metastases (hazard ratio, 0.68; 95% CI, 0.50-0.91), consistent with findings from the overall pooled study population (hazard ratio, 0.70; 95% CI, 0.61-0.81). Rates of treatment-related hepatic adverse events (primarily grade 1-2 liver enzyme elevations) were slightly higher in nivolumab-treated patients with liver metastases (10%) than in the overall pooled population (6%). Conclusions: After 3 years' minimum follow-up, nivolumab continued to demonstrate an OS benefit versus docetaxel in patients with advanced NSCLC. Similarly, nivolumab demonstrated an OS benefit versus docetaxel in patients with liver metastases, and remained well tolerated. Clinical trial registration: CheckMate 017: NCT01642004; CheckMate 057: NCT01673867.

Implementing multiplexed genotyping of non-small-cell lung cancers into routine clinical practice.

BACKGROUND: Personalizing non-small-cell lung cancer (NSCLC) therapy toward oncogene addicted pathway inhibition is effective. Hence, the ability to determine a more comprehensive genotype for each case is becoming essential to optimal cancer care. METHODS: We developed a multiplexed PCR-based assay (SNaPshot) to simultaneously identify >50 mutations in several key NSCLC genes. SNaPshot and FISH for ALK translocations were integrated into routine practice as Clinical Laboratory Improvement Amendments-certified tests. Here, we present analyses of the first 589 patients referred for genotyping. RESULTS: Pathologic prescreening identified 552 (95%) tumors with sufficient tissue for SNaPshot; 51% had ≥1 mutation identified, most commonly in KRAS (24%), EGFR (13%), PIK3CA (4%) and translocations involving ALK (5%). Unanticipated mutations were observed at lower frequencies in IDH and ß-catenin. We observed several associations between genotypes and clinical characteristics, including increased PIK3CA mutations in squamous cell cancers. Genotyping distinguished multiple primary cancers from metastatic disease and steered 78 (22%) of the 353 patients with advanced disease toward a genotype-directed targeted therapy. CONCLUSIONS: Broad genotyping can be efficiently incorporated into an NSCLC clinic and has great utility in influencing treatment decisions and directing patients toward relevant clinical trials. As more targeted therapies are developed, such multiplexed molecular testing will become a standard part of practice.

Platelet lipid(s) bound to albumin increases endothelial electrical resistance: mimicked by LPA.

The objectives were to determine whether the permeability-decreasing activity of platelet-conditioned medium (PCM) is associated with a lipid bound to albumin and whether lysophosphatidic acid (LPA) is present in the PCM. A decrease in permeability was assessed by an increase in electrical resistance across endothelial cell monolayers derived from bovine pulmonary arteries and microvessels. The Sephacryl S-200 fraction of PCM that contained albumin, the albumin immunoprecipitate from the PCM, and the methanol extract from the albumin immunoprecipitate all increased endothelial electrical resistance. Increased electrical resistance induced by PCM was not abolished by boiling and was mimicked by 1-oleoyl-LPA and 1-palmitoyl-LPA. Analysis of a methanol-chloroform extract of one sample of PCM by electrospray mass spectrometry revealed many fatty acids, ceramide, diacylglycerol, phosphatidic acid, and palmitoyl-LPA, but analysis of a second sample of PCM and the methanol extract of its albumin immunoprecipitate revealed no LPA, only lipids. These findings indicate that a bioactive lipid(s), possibly LPA, released from platelets and subsequently bound to albumin forms an active complex that decreases endothelial permeability.

Platelet-conditioned medium increases endothelial electrical resistance independently of cAMP/PKA and cGMP/PKG.

Platelets release a soluble factor into blood and conditioned medium (PCM) that decreases vascular endothelial permeability. The objective of this study was to determine the signal-transduction pathway that elicits this decrease in permeability. Permeability-decreasing activity of PCM was assessed by the real-time measurement of electrical resistance across cell monolayers derived from bovine pulmonary arteries and microvessels. Using a desensitization protocol with cAMP/protein kinase A (PKA)-enhancing agents and pharmacological inhibitors, we determined that the activity of PCM is independent of PKA and PKG. Genistein, an inhibitor of tyrosine kinases, prevented the increase in endothelial electrical resistance. Because lysophosphatidic acid (LPA) has been proposed to be responsible for this activity of PCM and is known to activate the G(i) protein, inhibitors of the G protein pertussis toxin and of the associated phosphatidylinositol 3-kinase (PI3K) wortmannin were used. Pertussis toxin and wortmannin caused a 10- to 15-min delay in the characteristic rise in electrical resistance induced by PCM. Inhibition of phosphorylation of extracellular signal-regulated kinase with the mitogen-activated kinase kinase inhibitors PD-98059 and U-0126 did not prevent the activity of PCM. Similar findings with regard to the cAMP protocols and inhibition of G(i) and PI3K were obtained for 1-oleoyl-LPA. These results demonstrate that PCM increases endothelial electrical resistance in vitro via a novel, signal transduction pathway independent of cAMP/PKA and cGMP/PKG. Furthermore, PCM rapidly activates a signaling pathway involving tyrosine phosphorylation, the G(i) protein, and PI3K.

Transfusion in unilateral total knee arthroplasty.

Blood transfusion requirements were analyzed in 102 total knee arthroplasties in 92 patients. All components were cemented, and no postoperative drainage was used. Six patients received transfusions; two of these patients received transfusions for symptoms and four received transfusions prophylactically. These findings do not support the routine practice of preoperative autologous blood donation.

Some electrochemical and chemical properties of methoxatin and analogous quinoquinones.

The present study establishes relationships between structure and reactivity for the pyrroloquinoline and phenanthroline quinones. The electrochemical reductions of 1,7- and 1,10-phenanthroline-5,6-quinones, like other quinones, are reversible and occur by 2e- transfer in a single step in aqueous solution and by two 1e(-)-transfer steps in aprotic media. The electron-withdrawing pyridine moieties both increase their potentials and stabilize their aprotic semiquinones. The electrochemistry of the cofactor methoxatin and its trimethylester derivative is similar to the phenanthroline quinones in aqueous solution. However, the electrochemical reductions of methoxatin and its triester in aprotic solutions are characterized by at least three potentials, each accounting for less than 1e-. This has been explained by the proposal of semiquinone complexing with itself and with quinone. Despite an electron-donating pyrrole moiety, methoxatin and its trimethylester have relatively high potentials in aprotic solution. This is presumably due to stabilization of radical anions by the aforementioned complexing or by delocalization with carboxylic acid and ester groups. The reduction potential of methoxatin, in both aqueous and aprotic solvent, suggests that oxidation of methanol should be a thermodynamically favorable process. No evidence for an electrochemically reduced state lower than the quinol was found for any of the compounds. Chemical reactivity is influenced by the orientation of the pyridine nitrogen. The two quinones with a pyridine nitrogen peri to a quinone carbonyl add and oxidize nucleophiles most readily.