REGOMA-OSS: a large, Italian, multicenter, prospective, observational study evaluating the efficacy and safety of regorafenib in patients with recurrent glioblastoma

BACKGROUND

In the randomized phase II REGOMA trial, regorafenib showed promising activity in patients with recurrent glioblastoma. We conducted a large, multicenter, prospective, observational study to confirm the REGOMA data in a real-world setting.

PATIENTS AND METHODS

The major inclusion criteria were histologically confirmed diagnosis of glioblastoma according to the World Health Organization (WHO) 2016 classification and relapse after radiotherapy with concurrent/adjuvant temozolomide treatment, good performance status [Eastern Cooperative Oncology Group performance status (ECOG PS 0-1)] and good liver function. Regorafenib was administered at the standard dose of 160 mg/day for 3 weeks on/1 week off. Brain magnetic resonance imaging was carried out within 14 days before starting regorafenib and every 8-12 weeks. The primary endpoint was overall survival (OS). The secondary endpoints were progression-free survival (PFS), objective response rate, disease control rate (DCR), safety and health-related quality of life. The Response Assessment in Neuro-Oncology (RANO) criteria were used for response evaluation and Common Terminology Criteria for Adverse Events (CTCAE) version 5 for assessment of adverse events (AEs).

RESULTS

From September 2020 to October 2022, 190 patients with recurrent glioblastoma were enrolled from 30 cancer centers in Italy: their median age was 58.5 years [interquartile range (IQR) 53-67 years], 68% were male and 85 (44.7%) were in optimal clinical condition (ECOG PS 0). The number of patients taking steroids at baseline was 113 (60%); the second surgery was carried out in 39 (20.5%). O6-methylguanine-DNA methyltransferase (MGMT) was methylated in 80 patients (50.3%) and 147 (92.4%) of the patients analyzed had isocitrate dehydrogenase (IDH) wild type. The median follow-up period was 20 months (IQR 15.6-25.5 months). The median OS was 7.9 months ([95% confidence interval (CI) 6.5-9.2 months] and the median PFS was 2.6 months (95% CI 2.3-2.9 months). Radiological response was partial response and stable disease in 13 (7.3%) and 26 (14.6%) patients, respectively, with a DCR of 21.9%. The median number of regorafenib cycles per patient was 3 (IQR 2.0-4.0). Grade 3-4 drug-related adverse events were reported in 22.6% of patients. A dose reduction due to AEs was required in 36% of patients. No deaths were considered as treatment-related AEs.

CONCLUSIONS

This large, real-world observational study showed similar OS with better tolerability of regorafenib in patients with relapsed glioblastoma compared with the REGOMA study.

The transcription factor HIF2α partakes in the differentiation block of acute myeloid leukemia

One of the defining features of acute myeloid leukemia (AML) is an arrest of myeloid differentiation whose molecular determinants are still poorly defined. Pharmacological removal of the differentiation block contributes to the cure of acute promyelocytic leukemia (APL) in the absence of cytotoxic chemotherapy, but this approach has not yet been translated to non-APL AMLs. Here, by investigating the function of hypoxia-inducible transcription factors HIF1α and HIF2α, we found that both genes exert oncogenic functions in AML and that HIF2α is a novel regulator of the AML differentiation block. Mechanistically, we found that HIF2α promotes the expression of transcriptional repressors that have been implicated in suppressing AML myeloid differentiation programs. Importantly, we positioned HIF2α under direct transcriptional control by the prodifferentiation agent all-trans retinoic acid (ATRA) and demonstrated that HIF2α blockade cooperates with ATRA to trigger AML cell differentiation. In conclusion, we propose that HIF2α inhibition may open new therapeutic avenues for AML treatment by licensing blasts maturation and leukemia debulking.

miR-126 identifies a quiescent and chemo-resistant human B-ALL cell subset that correlates with minimal residual disease

Complete elimination of B-cell acute lymphoblastic leukemia (B-ALL) by a risk-adapted primary treatment approach remains a clinical key objective, which fails in up to a third of patients. Recent evidence has implicated subpopulations of B-ALL cells with stem-like features in disease persistence. We hypothesized that microRNA-126, a core regulator of hematopoietic and leukemic stem cells, may resolve intratumor heterogeneity in B-ALL and uncover therapy-resistant subpopulations. We exploited patient-derived xenograft (PDX) models with B-ALL cells transduced with a miR-126 reporter allowing the prospective isolation of miR-126(high) cells for their functional and transcriptional characterization. Discrete miR-126(high) populations, often characterized by MIR126 locus demethylation, were identified in 8/9 PDX models and showed increased repopulation potential, in vivo chemotherapy resistance and hallmarks of quiescence, inflammation and stress-response pathway activation. Cells with a miR-126(high) transcriptional profile were identified as distinct disease subpopulations by single-cell RNA sequencing in diagnosis samples from adult and pediatric B-ALL. Expression of miR-126 and locus methylation were tested in several pediatric and adult B-ALL cohorts, which received standardized treatment. High microRNA-126 levels and locus demethylation at diagnosis associate with suboptimal response to induction chemotherapy (MRD > 0.05% at day +33 or MRD+ at day +78).

Abstract B027: The transcription factor HIF2alpha partakes in the differentiation block of acute myeloid leukemia

Acute myeloid leukemia (AML) is characterized by epigenetic silencing of differentiation genes and accumulation of aberrant myeloid cells arrested at different stages of myeloid development. The combination of epigenetic and differentiation therapies represents an attractive opportunity for AML patients by promoting chromatin remodeling at differentiation genes and induction of terminal maturation and leukemia debulking. The aim of our work is to define the function of the hypoxia inducible transcription factor HIF2alpha in the pathogenesis of AML. By its genetic inactivation and pharmacological inhibition in AML cell lines and patient-derived xenograft models, we found that HIF2alpha acts as a novel regulator of the AML differentiation block and promotes leukemia progression. Gene expression profiling of HIF2alpha-dependent transcriptome revealed that HIF2alpha mainly promotes the expression of genes involved in transcriptional modulation and epigenetic modifications, whilst inhibiting genes of myeloid maturation and activation. Mechanistically, inhibition of HIF2alpha results in decreased global levels of the heterochromatin marker H3K27me3, which is specifically deposited by the catalytic subunit EZH2 of the Polycomb repressive complex 2. Intriguingly, we found that HIF2alpha and EZH2 cooperate at favoring EZH2-mediated deposition of H3K27me3 at reverse hypoxia responsive elements in the regulatory regions of myeloid maturation genes. Additionally, we demonstrate that HIF2alpha is positively regulated by the pro-differentiation agent all-trans retinoic acid (ATRA), and its inhibition cooperates with ATRA in triggering AML cell differentiation. In conclusion, we provide new mechanistic insights into the role of HIF2alpha in the pathogenesis of AML, by promoting an undifferentiated state via EZH2-mediated epigenetic silencing of myeloid differentiation genes. Importantly, small molecule inhibitors of HIF2alpha have been recently generated and are tested for solid cancers. Therefore, HIF2alpha inhibition may open new therapeutic avenues for AML patients and add therapeutic value to ATRA-based therapies by interrupting HIF2alpha upregulation and promoting an epigenetic state permissive to maturation of leukemic blasts and leukemia exhaustion.

Citation Format: Daniela Magliulo, Carolina Caserta, Serena Belluschi, Cristina Fracassi, Kety Giannetti, Raffaella Pini, Ettore Zapparoli, Stefano Beretta, Eleonora Draghi, Marco J. Morelli, Raffaella Di Micco, Bernhard Gentner, Luca Vago, Rosa Bernardi. The transcription factor HIF2alpha partakes in the differentiation block of acute myeloid leukemia. [abstract]. In: Proceedings of the AACR Special Conference: Cancer Epigenomics; 2022 Oct 6-8; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2022;82(23 Suppl_2):Abstract nr B027.

First-line avelumab for patients with PD-L1-positive metastatic or locally advanced urothelial cancer who are unfit for cisplatin

BACKGROUND

Cisplatin-based chemotherapy is the most recommended treatment for metastatic urothelial cancer (mUC). However, about 50% of patients are considered to be cisplatin ineligible. Anti-PD1/PD-L1 therapies have, nevertheless, increased the options available to clinicians and are especially valuable for treating these patients. This study therefore tested the activity and safety of avelumab as first-line therapy for mUC.

PATIENTS AND METHODS

Patients with mUC who were ineligible for cisplatin-based chemotherapy were screened centrally for PD-L1 expression and only those with a tumour proportion score (TPS) ≥5% were enrolled in the trial. The primary endpoint was 1-year overall survival (OS), and the secondary endpoints were median OS, median PFS, the ORR, the duration of the response, safety, and tolerability. All the survival rates were estimated with the Kaplan-Meier product-limit methodology and compared across groups using the log-rank test.

RESULTS

198 patients were screened, with 71 (35.9%) whose PD-L1 expression was ≥5% enrolled in the study. The median age was 75 years, bladder cancer was the primary tumour in 73.2% of cases, and 25.3% had liver metastases. The main reasons for the cisplatin ineligibility were a low rate of creatinine clearance (< 60 ml/min), present in 70.4% of patients, and an ECOG performance status of 2, which affected 31%. The median OS was 10.0 months (95% CI, 5.5-14.5) and 43% of patients were alive at one year. A complete response was achieved in 8.5% of cases and 15.5% had a partial response. Adverse any-grade and high-grade events occurred in 49.3% and 8.5% of patients, respectively. A grade 3 infusion reaction was the only high-grade treatment-related adverse event. No treatment-related deaths were reported.

CONCLUSIONS

This ARIES trial confirmed the activity and safety of avelumab for treating mUC, adding a new therapy option to the armamentarium of checkpoint inhibitors already approved for platinum-ineligible, locally advanced/mUC.

Myeloid cell-based delivery of IFN-γ reprograms the leukemia microenvironment and induces anti-tumoral immune responses

The immunosuppressive microenvironment surrounding tumor cells represents a key cause of treatment failure. Therefore, immunotherapies aimed at reprogramming the immune system have largely spread in the past years. We employed gene transfer into hematopoietic stem and progenitor cells to selectively express anti-tumoral cytokines in tumor-infiltrating monocytes/macrophages. We show that interferon-γ (IFN-γ) reduced tumor progression in mouse models of B-cell acute lymphoblastic leukemia (B-ALL) and colorectal carcinoma (MC38). Its activity depended on the immune system's capacity to respond to IFN-γ and drove the counter-selection of leukemia cells expressing surrogate antigens. Gene-based IFN-γ delivery induced antigen presentation in the myeloid compartment and on leukemia cells, leading to a wave of T cell recruitment and activation, with enhanced clonal expansion of cytotoxic CD8+ T lymphocytes. The activity of IFN-γ was further enhanced by either co-delivery of tumor necrosis factor-α (TNF-α) or by drugs blocking immunosuppressive escape pathways, with the potential to obtain durable responses.

Immune-inflammatory biomarkers as prognostic factors for immunotherapy in pretreated advanced urinary tract cancer patients: an analysis of the Italian SAUL cohort

Background

Reliable and affordable prognostic and predictive biomarkers for urothelial carcinoma treated with immunotherapy may allow patients' outcome stratification and drive therapeutic options. The SAUL trial investigated the safety and efficacy of atezolizumab in a real-world setting on 1004 patients with locally advanced or metastatic urothelial carcinoma who progressed to one to three prior systemic therapies.

Patients and methods

Using the SAUL Italian cohort of 267 patients, we investigated the prognostic role of neutrophil-to-lymphocyte ratio (NLR) and systemic immune-inflammation index (SII) and the best performing one of these in combination with programmed death-ligand 1 (PD-L1) with or without lactate dehydrogenase (LDH). Previously reported cut-offs (NLR >3 and NLR >5; SII >1375) in addition to study-defined ones derived from receiver operating characteristic (ROC) analysis were used.

Results

The cut-off values for NLR and SII by the ROC analysis were 3.65 (sensitivity 60.4; specificity 63.0) and 884 (sensitivity 64.4; specificity 67.5), respectively. The median overall survival (OS) was 14.7 months for NLR <3.65 [95% confidence interval (CI) 9.9-not reached (NR)] versus 6.0 months for NLR ≥3.65 (95% CI 3.9-9.4); 14.7 months for SII <884 (95% CI 10.6-NR) versus 6.0 months for SII ≥884 (95% CI 3.7-8.6). The combination of SII, PD-L1, and LDH stratified OS better than SII plus PD-L1 through better identification of patients with intermediate prognosis (77% versus 48%, respectively). Multivariate analyses confirmed significant correlations with OS and progression-free survival for both the SII + PD-L1 + LDH and SII + PD-L1 combinations.

Conclusion

The combination of immune-inflammatory biomarkers based on SII, PD-L1, with or without LDH is a potentially useful and easy-to-assess prognostic tool deserving validation to identify patients who may benefit from immunotherapy alone or alternative therapies.

•

Reliable biomarkers for immunotherapy may assist in treatment decision making and clinical trial design and interpretation.

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Immune-inflammatory biomarkers were investigated for their prognostic role within the Italian SAUL study cohort.

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ROC-based cut-offs were 3.65 for NLR and 884 for SII.

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Both NLR and SII were prognostic with SII performing slightly better than NLR.

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The combination of SII, PD-L1, and LDH stratified OS better than SII + PD-L1; both were independent prognostic factors.

Seroepidemiology of HEV and HAV in two populations with different socio-economic levels and hygienic/sanitary conditions

The epidemiological scenarios of hepatitis E virus (HEV) and hepatitis A virus (HAV) infections have changed in the last few decades, but precise epidemiological data on the prevalence of anti-HEV and anti-HAV, alone or in combination, in the general population are scanty. We investigated HEV and HAV seroprevalence comparing two population samples living in Northern (Abbiategrasso, Milan) and Southern Italy (Cittanova, Reggio Calabria), the latter being characterized by a poorer socio-economic level and hygienic/sanitary conditions. Based on census records, we randomly enrolled and tested 3,365 subjects (Abbiategrasso, n = 2,489; Cittanova, n = 876) aged 18-75 years for anti-HAV and anti-HEV. Anti-HAV (71.3 % vs 52.5 %) and anti-HEV (17.8 % vs 9.0 %) prevalence rates were higher in Southern Italy (both p < 0.001). Most anti-HEV-positive subjects also had anti-HAV. Subjects testing positive for anti-HAV, alone or with anti-HEV, were older (p < 0.001 in both populations) and showed a trend toward declining prevalence in the youngest birth cohorts. The prevalence of subjects with a positive result for anti-HEV alone did not change in birth cohorts in the two towns. Detection of anti-HEV was independently associated with anti-HAV, town, birth cohort, and education level in multivariate analysis. Low socio-economic level and hygienic/sanitary conditions are associated with high HAV and HEV seroprevalence rates in Italy. Recent improvements, especially in the South, have led to a declining prevalence of anti-HAV, alone or with anti-HEV. Seroprevalence of HEV alone is uniformly low and does not change in birth cohorts born between 1938 and 1993.

Aprepitant versus metoclopramide, both combined with dexamethasone, for the prevention of cisplatin-induced delayed emesis: a randomized, double-blind study

BACKGROUND

A combination of aprepitant, a 5-HT3 receptor antagonist (r.a.), and dexamethasone is recommended for the prophylaxis of cisplatin-induced nausea and vomiting in the acute phase, and aprepitant + dexamethasone (A + D) in the delayed phase. The aim of this study was to verify if A + D is superior to metoclopramide plus dexamethasone (M + D) in preventing delayed emesis in cancer patients receiving the same prophylaxis for acute emesis.

PATIENTS AND METHODS

A randomized double-blind study comparing A + D versus M + D was completed in previously untreated cancer patients. Before chemotherapy, all patients were treated with intravenous palonosetron 0.25 mg and dexamethasone 12 mg, and oral aprepitant 125 mg. On day 2-4, patients randomly received oral dexamethasone 8 mg plus aprepitant 80 mg once daily (days 2-3) or metoclopramide 20 mg four times daily plus dexamethasone 8 mg bid. Primary endpoint was rate of complete response (no vomiting, no rescue treatment) in day 2-5 after chemotherapy.

RESULTS

Due to difficulty in the accrual of patients, 303 of the 480 planned patients were enrolled, 284 were fully evaluable, 147 receiving A + D, 137 M + D. Day 1 results were similar in both arms. On day 2-5, complete response rate was not significantly different (80.3% with A + D versus 82.5% with M + D, P < 0.38, respectively), and all secondary endpoints were also similar (complete protection, total control, no vomiting, no nausea, and score of Functional Living Index-Emesis; P < 0.24). Adverse events incidence was not significantly different between the two treatments.

CONCLUSIONS

In cancer patients submitted to cisplatin-based chemotherapy, receiving the same antiemetic prophylaxis for acute emesis, A + D is not superior to M + D in preventing delayed emesis, and both treatments present similar toxicity.

CLINICALTRIALSGOV NUMBER

NCT00869310.

Antiviral treatment for hepatitis C virus infection: effectiveness at general population level in a highly endemic area

BACKGROUND

Peginterferon plus ribavirin treatment induced a sustained virological response in >50% of HCV-RNA-positive individuals enrolled in published clinical trials.

AIM

To determine anti-HCV treatment effectiveness at a general population level.

PATIENTS AND METHODS

In 2002, a 1:5 random sample of >11 years old inhabitants of a small Italian town (Cittanova) was invited for HCV screening. HCV-RNA-positive individuals were evaluated for antiviral treatment.

RESULTS

1645 of 1924 invited individuals (85.5%) participated in the screening. 84 HCV-RNA-positive individuals were detected: median age was 65 years (range: 32-87); 67% was infected with genotype 1 or 4. Antiviral treatment was judged unnecessary for 43 (51.2%), due to persistently normal alanine aminotransferases, mild disease at liver biopsy or age >70 years without cirrhosis. Twenty-eight of the remaining 41 patients (68.3%) were ineligible for treatment, because of medical/psychiatric contraindications (42.9%), alcohol/drug abuse (17.9%), decompensated cirrhosis/hepatocellular carcinoma (17.9%), not attending official appointments (10.7%), previous intolerance/non-response to interferon plus ribavirin (10.7%). 5 of 13 eligible patients (38.5%) did not receive treatment (4 refused and 1 accidental death). 3 of 8 treated patients (37.5%) reached a sustained virological response.

CONCLUSIONS

Although efficacy of anti-HCV therapy improved in recent years, we found that low eligibility to treatment still limited its effectiveness at general population level in a highly endemic town.

Randomized prospective phase II trial of two schedules of sorafenib daily and interferon-α2a (IFN) in metastatic renal cell carcinoma (RAPSODY): GOIRC Study 0681

5100

Background: Sorafenib is an oral multi-kinase inhibitor with a demonstrated efficacy in MRCC (Eisen, ASCO 2006). IFN is a pleiotropic molecule with an antiangiogenic activity probably dose and schedule-dependent (Folkman, 1992). Aim of this study was to evaluate the activity and safety of sorafenib combined with IFN in two different schedules. Methods: Eligible patients had metastatic renal cell carcinoma (MRCC) with a clear cell component = 50%, previous nephrectomy, ECOG Performance Status 0–2, no cerebral metastases or previous treatment, measurable disease; any Motzer’s score was allowed. Patients received oral sorafenib 400mg BID continuously plus sc IFN, 9 MU three times a week (arm-A) or 3 MU five times a week (arm-B), started 7 days after sorafenib to increase compliance. Planned sample size of this single-stage study was 100 cases to be enrolled over 18 months. Primary end points: Progression Free Survival (PFS) in the two arms and safety; secondary end-points: overall response (intention-to treat analysis) and overall survival. Results: Between January 2006 and January 2007 all the expected cases were enrolled into the study (median age 63 years, range 34–82; male/female: 71/29). Of 63 patients for whom a post baseline assessment was available (31 in arm A and 32 in arm B), 16 achieved a partial response (25.4%: 29% in arm A, 95% CI 13.2–44.9 and 22% in arm B, 95% CI 7.6–36.2), 26 had a stable disease (41.3%: 29% in arm A and 53% in arm B) and 21 progressed (33.3%: 42% in arm A and 25% in arm B). Due to the short follow-up period PFS data are not yet available. The most common grade 3/4 toxicities affecting more than 5% of the pts were equally distributed between arms except for fatigue and skin rash (respectively 19% and 8%, only arm A): hypophosphatemia (43%), hand-foot syndrome (22%), anorexia, stomatitis, hyperamylasemia (11% each), diarrhea (8%) and hyperlipasemia (5%). Conclusions: With an overall response rate of 25.4% and a tumor control rate (partial response + stable disease) of 66.7% (58.1% in arm A, 95% CI 40.7–75.5 and 75.0% in arm B, 95% CI 60.0–90.0; p = ns) sorafenib plus IFN can be considered a promising regimen in MRCC. Further investigations of the active and safe low-dose IFN combination arm are warranted.

[Table: see text]

Protein kinase inhibitors in the treatment of renal cell carcinoma: sorafenib

Sorafenib is an orally available multikinase inhibitor active on vascular endothelial growth factor receptor-2 and -3, platelet-derived growth factor receptor-beta, B-RAF, C-RAF, flt3 and C-Kit. Phase I studies showed its activity on renal cell carcinoma (RCC) and other neoplasms and identified the schedule of 400 mg (two tablets) b.i.d. as better tolerated and potentially active. The original design selected for the principal phase II trial, randomization discontinuation trial, showed the particular activity profile of this drug: low objective response rates but significant increases in progression-free survival [PFS, which frequently translate in increased overall survival (OS)]. A pattern of response completely agrees with an antiangiogenic (cytostatic) agent. The potential efficacy of sorafenib was confirmed in immunotherapy-refractory advanced RCC cases by 'TARGETs', the largest randomized double-blind study ever carried out in kidney cancer. With a doubled PFS, a trend in OS and a modest toxicity profile, mainly grade 1-2 skin toxicity and diarrhea, sorafenib has been recently approved from the Food and Drug Administration and European Agency for the Evaluation of Medicinal Products for the second-line treatment of advanced RCC. Numerous trials are ongoing to test new schedules and drug combinations, while promising results were recently achieved also in hepatocellular carcinoma. With drugs such as sorafenib, angiogenesis could become an Achilles's heel for RCC.

Distribution of spinocerebellar Purkinje cell responses to passive forelimb movements in the rat

We recorded Purkinje cell activity throughout the spinocerebellum of anaesthetized rats while imposing circular passive movements to the unrestrained forelimb. The aim was to understand the type of processing of sensory information occurring at the level of the cerebellar cortex, on the basis that precerebellar sensory neurons have been shown to represent whole limb movement parameters better than single joint movements. We observed that neurons representing sensory aspects of arm movements were scattered throughout the spinocerebellar cortex without a distinct segregation from those that did not respond, albeit the relative density of responsive and unresponsive neurons was quite variable and depended on the area of the cortex. Furthermore, Purkinje cells that responded significantly to the arm movement cycles all showed the same response pattern consisting of a firing rate increase during the downward extension of the arm. These results are discussed as suggesting a coordinate framework for the representation of proprioceptive information in the cerebellum congruent to that observed for encoding motor parameters.

Sensory representation of passive movement kinematics by rat's spinocerebellar Purkinje cells

In this paper we examined Purkinje cells' sensory representations of kinematic parameters of passive movements imposed to the forelimb of anesthetized rats. Simple spike Purkinje cell activity was recorded while the rat's ipsilateral forearm was moved passively along circular footpaths at two different speeds. We found that the activity of 35.33% (165/467) of the neurons was significantly modulated during movement cycles. A multivariate regression analysis indicated that movement direction was the predominant factor in determining Purkinje cell activity, whereas movement velocity (i.e. the combination of movement direction and speed) was represented to a much lesser degree. Based on this result, we might suggest that a cortical efferent copy is necessary to the cerebellum in order to elaborate a movement velocity signal.

Electromyographic effects of serotonin application into the lateral vestibular nucleus

Electromyographic responses (EMGs) of limb muscles were studied during microiontophoretic application of 5-hydroxytryptamine (5-HT) into the lateral vestibular nucleus (LVN) or the spinal vestibular nucleus (SpVe) of anaesthetized rats. The aim was to ascertain whether the level of 5-HT in these nuclei was able to modulate muscle responsiveness. Increased levels of 5-HT in LVN (and to a weaker extent in SpVe) enhanced the EMGs of proximal extensor muscles and depressed those of flexors. The 5-HT2A receptor antagonist ketanserin, applied into the LVN, prevented 5-HT effects on EMG-evoked responses. It is concluded that 5-HT can modulate the motor output via the vestibulospinal pathway, exerting a differential control over flexor and extensor muscles.

HIV protease substrate conformation: modulation by cyclophilin A

Cyclophilin A (CyPA), a cytosolic peptidyl-prolyl trans-cis isomerase can accelerate the trans-cis isomerization of Xxx-Pro peptide bonds. One- and two-dimensional 1H-NMR spectroscopy were used to determine that the heptapeptide Ser-Gln-Asn-Tyr-Pro-Ile-Val, a model peptide of an HIV-1 protease cleavage site in the gag polyprotein of HIV-1, is a substrate for CyPA. Experiments revealed a slow exchange about the Tyr-Pro peptide bond with 30 +/- 5% in the cis conformation (pH 1-9). While the interconversion rate is too slow to measure by kinetic NMR methods in the absence of CyPA, these methods, saturation transfer and NOE experiments, established that CyPA enhanced the rate of trans-cis interconversion, a process inhibited by cyclosporin A (CsA). With a substrate:CyPA ratio of 40:1, an interconversion rate of 2.5 s(-1) at 25 degrees C was observed.

Alternative pathway complement activation induces proinflammatory activity in human proximal tubular epithelial cells

BACKGROUND

Proximal tubular epithelial cells express a surface C3-convertase activity which induces C fixation and insertion of the C5b-9 membrane attack complex (MAC) into the cell plasma membrane. The physiopathological consequences of this phenomenon are unknown.

METHODS

The effect of C fixation on the production of inflammatory mediators by human proximal tubular epithelial cells in culture was explored.

RESULTS

Proximal tubular epithelial cells incubated with a sublytic amount of normal human serum as a source of C, but not with heat-inactivated human serum, showed a time-dependent calcium influx and a concomitant release of 14C-arachidonic acid (14C-AA). Eicosanoid synthesis following the arachidonic acid mobilization was studied as prostaglandin E2 release. Mg2+/EGTA, which did not prevent C activation by the C3-convertase, and p-bromodiphenacyl bromide a phospholipase A2-inhibitor, inhibited mobilization of 14C-AA. These results suggest the activation of an extracellular Ca(2+)-dependent, phospholipase A2. Complement fixation was associated with the synthesis of proinflammatory cytokines such as IL-6 and TNF-alpha. Experiments with C6-deficient sera indicated that the release of 14C-AA and the production of cytokines were dependent on the insertion of the terminal components of complement in the plasma membrane. Indeed, the reconstitution of normal haemolytic activity of C6-deficient sera with purified C6 restored also the release of 14C-AA and the production of cytokines.

CONCLUSIONS

In vitro complement activation on the proximal tubular cell surface triggers the generation of proinflammatory mediators, which may potentially contribute to the pathogenesis of tubulointerstitial injury.

Interstitial deletion of 4(q21q25) in a liveborn male

We describe a liveborn male with a de novo deletion of 4(q21q25). The findings in this infant are compared with those of other 4q interstitial deletion patients with similar break-points. Given the reproducible findings including skull asymmetry, cardiac defects, renal cysts, "butterfly" vertebrae, as well as a particular dysmorphic face with developmental delay, there is evidence for an interstitial 4q deletion syndrome.

Modeling of biological and medical systems: a systemic strategy

A strategy in the frame of General System Theory is proposed for the study of biological systems for medical purposes. Its definition and use requires in each experiment the collaboration between physician and system scientists and hence the definition of a common language, by which the real system under study is described. The strategy is based on three intermingled steps: first an ingenuous model is proposed, gathering all the medical knowledge about the studied system, organized within an informal frame derived from the state space approach. Next, a functional model is derived, enlightening the organization of the relations in the medical model. Finally, this organization is formalized by the most suitable algebraic tools, which are thereafter translated into APL programs. This last version is used for simulation, which is exploited not only as a tool to describe and make provisions on the dynamics of the models, but also to deepen and improve the knowledge about the observed system.