Plasma levels of JAK2 mRNA in patients with chronic myeloproliferative diseases with and without V617F mutation: implications for prognosis and disease biology

The association of V617F JAK2 expression levels with disease behavior has not been studied in patients with nonchronic myelogenous leukemia (CML) myeloproliferative disease (MPD). We found plasma levels of total JAK2 mRNA to be higher in patients with non-CML MPD (n=175) than in CML patients (n=45) and normal controls (n=58) (each P<0.001). Overall survival was studied in 68 patients and showed positive correlation with levels of total and mutant JAK2 mRNA in patients with the V617F mutation, but not those without the mutation. These findings suggest that total JAK2 expression levels play a role in the biology of the disease in V617F-positive patients, and a therapy aiming at downmodulating the expression of the total JAK2 mRNA should be considered. In conclusion, we studied JAK2 total and V6217F mutant mRNA levels in plasma. We show high levels of JAK2 expression in MPD patients and these levels correlate with survival.

Adult acute erythroleukemia: an analysis of 91 patients treated at a single institution

Acute erythroleukemia (AML-M6) is an uncommon subtype of acute myeloid leukemia (AML); it is considered to have a poor prognosis. From 1 January 1980 to 21 May 2008, 91 patients with newly diagnosed AML-M6 were seen at the University of Texas-M.D. Anderson Cancer Center (UT-MDACC). Forty-five patients (50%) had a history of myelodysplatic syndrome (MDS), compared with 41% in our control group (patients with other AML subtypes) (P=0.08). Poor-risk cytogenetics were more common in patients with AML-M6 (61% versus 38%, P=0.001). Complete remission rates were 62% for patients with AML-M6, comparing with 58% for the control group (P=0.35). Median disease free survival (DFS) for patients with AML-M6 was 32 weeks, versus 49 weeks for the control group (P=0.05). Median overall survival (OS) of patients with AML-M6 was 36 weeks, compared with 43 weeks for the control group (P=0.60). On multivariate analysis for DFS and OS, AML-M6 was not an independent risk factor. AML-M6 is commonly associated with a previous diagnosis of MDS and poor-risk karyotype. The diagnosis of AML-M6 does not impart by itself a worse prognosis, and treatment decisions on this disease should be guided by well known AML prognostic factors.

Prioritisation of Tests for the Prediction of Preeclampsia Complications: A Delphi Survey

BACKGROUND

Preeclampsia is associated with several maternal and fetal complications. Numerous tests - including patient history, physical examination findings, and laboratory investigations - are used to predict such complications in women with preeclampsia. At present, there are no robust systematic reviews or large studies examining the accuracy of tests that could predict complications in women with preeclampsia.

OBJECTIVE

To identify the tests (which include items of history, examination, and investigations) that are clinically relevant in predicting maternal and fetal complications in women with preeclampsia.

METHODS

A two-generational Delphi method was used to prioritize the clinically relevant tests that are considered helpful in predicting the maternal and fetal complications of preeclampsia.

RESULTS

Blood pressure was rated as the best predictor of complications with mean score (+/- SD) of 4.7 (+/- 0.47), followed by proteinuria 4.6 (+/- 0.5) and liver function tests 4.5 (+/- 0.52).

CONCLUSION

The list of tests that have been identified and prioritized will form the basis for future systematic reviews of the literature in this field.

Phase I/II study of oxaliplatin, fludarabine, cytarabine, and rituximab in patients (OFAR2) with Richter's syndrome (RS), and relapsed or refractory B-cell chronic lymphocytic leukemia (CLL)

7031

Background: The first Phase I-II clinical trial of oxaliplatin, fluradabine, Ara-C, and rituximab (OFAR1) demonstrated significant activity in refractory CLL and RS (Tsimberidou et al, J Clin Oncol, 2008;26:196). To enhance the response rate with a decrease in myelosuppression, the dose of oxaliplatin was increased to 30 mg daily, the dose of Ara-C was decreased to 0.5g/m2 daily and the optimal number of days of fluradabine and Ara-C administration was explored (OFAR2). Methods: The OFAR2 regimen consisted of oxaliplatin 30mg/m2, D1–4; fludarabine 30mg/m2, Ara-C 0.5 g/m2; rituximab 375mg/m2, D3; and pelfigrastim 6mg D6. Fludarabine and Ara-C were given on D2–3 (dose level 1) D2–4 (dose level 2) or D2–5 (dose level 3); courses were repeated every 4 wks. Prophylaxis for tumor lysis, DNA viruses, and PCP was given. Results: A total of 55 pts have been treated to date: 12 pts enrolled in phase I (dose level 1, n=3; dose level 2, n=6; and dose level 3, n=3). DLTs were noted in 2/3 pts in dose level 3 (G4 diarrhea, 1; G4 neutropenic sepsis, 1), therefore level 2 was the MTD. Forty-three pts were treated in the Phase II portion of the study (relapsed CLL, 35; RS, 8). The median age was 64 yrs (range, 40- 81); 50 (91%) had β2-microglobulin > 3 mg/L; platelets were < 100 x109/L in 22 pts; and 44 pts had > 1 prior therapies. FISH results were: 17p deletion, n=15; 11q del, n=7; trisomy 12, n=12; 13q del, n=8; normal, n=2; unknown, n=11. Overall, 33 pts had unmutated and 7 mutated IgVH gene; ZAP70 was positive in 30, and negative in 14. Six (46%) of 13 pts with 17p del by FISH responded to OFAR2 (nPR, 2; PR, 4). Eleven pts underwent stem cell transplantation as postremission or salvage therapy. The most common toxicity was myelosuppression. Conclusions: Preliminary results demonstrated that OFAR2 resulted in an overall response rate of 63%, had antileukemic activity in pts with 17p del and clinical outcomes appeared to be superior to those of OFAR1. Accrual is ongoing.

[Table: see text]

[Table: see text]

Acute myeloid leukemia (AML) in adolescents and young adults (AYA): The M. D. Anderson Cancer Center (MDACC) experience

7051

Background: AML is a heterogeneous group of hematopoietic neoplasms demonstrating clonal proliferation of myeloid precursors and is typically a disease of older adults. Little is known about outcomes of AYA with AML. Methods: We retrospectively analyzed all patients (pts) with AML treated at MDACC from 1965 to 2008. Pts ages 16 to 21 years (yrs) were defined as AYA. Results: Among 3,934 adult AML pts treated during this period, 163 pts (4%) were AYA with median age of 19 yrs. This cohort included 27 (17%) pts with Core Binding Factor (CBF)-AML [inv(16), t(8:21)] and 19 pts (12%) with acute promyelocytic leukemia (APL). Among the other pts, 50% had diploid cytogenetics, 11% had 5 or 7 abnormalities, 39% had other cytogenetic changes. Antecedent hematologic disorders were present in 33 pts (20%). Among 20 evaluated pts, FLT3 internal tandem duplication (ITD) was present in 4 pts and FLT3 kinase domain mutation was found in 2 pts. Complete remission (CR) rates were 89% for CBF AML, 79% for APL, and 75% for all other pts. Median survival for the total cohort was 1.7 yrs with 36% alive at 3 yrs, and median CR duration of 1.3 yrs (30% CR at 3 yrs). Outcome is better for pts with CBF leukemia (3 yr survival 56%, sustained CR 49%) and APL (3 yr survival 51%, sustained CR 36%) compared to other AML (3 yr survival 28%, sustained CR 24%). CR rates have improved from 71% in 1965–1984, to 85% in 1985–1994, and 83% after 1994. Similarly, overall survival (OS) has increased during the same time periods (3-yr survival 18%, 44%, and 53%, respectively) together with CR duration (3 yr CR duration 21%, 32% and 39%, respectively) as early mortality has decreased (11%, 8%, and 4%, respectively). To compare outcomes of AYA with older adults, we focused on those with diploid cytogenetics.CR for pts ages 16–21 was 81%, with 3 yr survival of 46%; for ages 22–45, CR was 75% and 3 yr survival 36%; for ages 46–60 CR was 68% with 3 yr survival 28%; and for pts age greater than 60, CR was 54% with 3 yr survival of 22%. Conclusions: The outcome of AYA pts with AML is significantly better than for older adults with AML. Despite the advances in treatments over time, there is still significant room for improvement, particularly among those AYA with AML other than CBF and APL. Exploration of new treatment options is needed in this patient population.

No significant financial relationships to disclose.

A phase II study of the tolerability and activity of weekly vincristine sulfate liposomes injection (VSLI) in adults with Philadelphia chromosome-negative (Ph-) acute lymphoblastic leukemia (ALL) in second relapse or progressing following two antileukemia treatment lines

7046

Background: VSLI (Marqibo) is a nanoparticle formulation of vincristine sulfate (VCR) encapsulated in sphingomyelin/cholesterol liposomes called Optisomes. The optisomal formulation lends itself to an improved pharmacokinetic profile and enhanced tumor penetration and concentration. Preclinical studies of VSLI showed enhanced efficacy versus standard VCR in a variety of solid and hematologic malignancies. VSLI has a maximum tolerated dose of 2.25 mg/m2 with no dose cap, while conventional VCR is dosed at 1.4 mg/m2 with a 2 mg dose cap. A previous study in relapsed ALL showed a complete response rate of 19%, warranting further study. Methods: Eligible adult subjects received single agent intravenous VSLI at a dose of 2.25 mg/m2 weekly with no dose cap. This international, multicenter, single-arm study will enroll approximately 56 subjects. Major endpoints include response rate and overall survival (OS). An interim analysis was planned following enrollment of 29 evaluable subjects. Results: 29 heavily pretreated subjects received ≥ 1 dose of VSLI. To date, at least 9 of 29 subjects had clearing of leukemic blasts and achievement of an M1 bone marrow. Based on preliminary data, the median OS is estimated to be 7.5 months (95% CI: 4.7–10.5) using the Kaplan-Meier method. The most frequent related adverse event (AE) was peripheral neuropathy (PN) (48%), half of which was grade 3. No grade 4 PN was reported. Six subjects had 8 treatment-associated grade 4 AEs of neutropenia (4), thrombocytopenia (2), anemia (1), and inappropriate antidiuretic hormone secretion (1). Conclusions: These results are encouraging, as VSLI was given as a single agent to a heavily pretreated patient population who nearly universally received prior VCR. This population typically has a very low response rate to anti-leukemia therapies. Early OS data compares favorably to an historical median OS of ∼ 2 months (8.7 weeks) in a second salvage population (data on file, M. D. Anderson). VSLI was well tolerated in these patients in the context of universal prior vincristine treatment.

[Table: see text]

A nine-gene predictor of therapy response in adult Philadelphia-chromosome positive acute lymphoblastic leukemia (Ph+ ALL)

7014

Background: Ph+ ALL in adults shows a poor response to therapy and high frequency of relapse. This study utilized a meta-analysis of previous genome-wide gene expression studies to define and validate a nine-gene predictor of outcome in Ph+ ALL patients. Methods: Normalized gene expression data from previously published studies of 672 ALL patients were analyzed to identify genes associated with therapy response. Expression of the selected genes was assessed using Applied Biosystems low density reverse transcription quantitative PCR (RT-qPCR) arrays in bone marrow (BM) samples from 27 adult Ph+ ALL patients treated with standard chemotherapy plus a tyrosine kinase inhibitor. Therapy responses were defined at the molecular level by monitoring BCR/ABL1 levels, and categorized into 3 groups: optimal, persistent and relapse. Median follow up was 6 months (range 4–15). Median disease-free survival among the optimal and relapse groups were 12 and 5 months respectively (p = 0.002). There was no statistical difference in age, initial peripheral blood white cell and BM blast counts, and initial normalized BCR/ABL1 levels between groups. Differentially expressed genes were selected using the significance analysis of microarrays (SAM). Hierarchical clustering and principal component analysis were applied to assess the correlation between gene expression pattern and therapy response. A predictive model was built using support vector machines. Differences in survival among groups were compared by Kaplan-Meier analysis. Results: Data mining and pathway analysis of the published data identified 46 genes in 7 pathways potentially associated with therapy response (p < 0.001). RT-qPCR results from a 15 case training set, 5 in each outcome group, identified 9 genes that classified the cases with 100% accuracy. Validation using an additional 12 cases showed 91.7% prediction accuracy (ROC error = 0.056). Compared with the initial diagnostic samples, gene expression pattern in relapsed samples shifted to that resembling the persistent group. Conclusions: Using data-trimming of whole genome expression studies, we defined and validated a nine-gene signature that is an independent predictive marker for therapy response in adult Ph+ ALL patients.

No significant financial relationships to disclose.

Feasibility of hypomethylating therapy in patients with renal insufficiency

7089

Background: Epigenetic therapy with hypomethylating agents (HA) is the standard of care in patients (pts) with myelodysplastic syndrome (MDS). Although neither 5-azacytidine (5AZA) nor 2'-deoxy azacytidine (decitabine; DAC) are excreted by the kidneys, many studies exclude pts with a serum creatinine level (sCr) ≥ 1.5 mg/dL. Moreover, there are no reports of use of these agents in pts with renal insufficiency (RI) commonly seen in pts with MDS. Methods: We investigated the outcomes of pts with RI and MDS, chronic myelomonocytic leukemia (CMML), or acute myeloid leukemia (AML) receiving therapy with HA. RI was defined by a sCr ≥ 1.5 mg/dL. We examined the compliance, dose adjustments (DA), and complications of treatment with DAC and 5AZA given at standard doses. We used the International Working Group criteria to evaluate the response rates. Data for pts with sCr > 2 mg/dL were compared to pts with sCr ≤ 2 mg/dL (Kantarjian H, et al, Blood. 2007). Results: Forty-two pts with sCr ≥ 1.5 mg/dL (including 17 with MDS, 16 with AML, and 9 with CMML) were treated with DAC or 5AZA alone or in combination with other agents (primarily histone deacetylase inhibitors). 14 (33%) and 28 (67%) of the pts received 5AZA and DAC, respectively. The median number of courses was 4.5 (range 1–19). 9 pts (21%) required treatment delay or discontinuation, and 12 pts (28%) required dose reduction (DR). Overall, 25 (62%) had an objective response (OR), and 4 pts (9%) had complete response (CR). 15 (36%) and 7 (17%) of the pts experienced episodes of therapy-related infections and bleeding, respectively. Among 12 pts who had sCr > 2.0 mg/dL, 7 pts (58%) required DR due to myelosuppression (n = 3) and to worsening of renal function (n = 4). The incidence of complications, DA, and the response rate were not significantly different for pts with sCr > 2.0 mg/dL. Conclusions: The use of HA is well tolerated in pts with MDS and AML and RI who achieved comparable OR rates to those without RI. Dose adjustment might be required in some pts.

[Table: see text]

[Table: see text]

Results of a phase I study of clofarabine (CLO) plus cyclophosphamide (CY) in adult patients (pts) with relapsed and/or refractory acute lymphoblastic leukemia (ALL)

7020

Background: CLO is a second generation nucleoside analog with FDA approval for children with ALL relapse. Single agent CLO in adult ALL was less active so that combinations of CLO with other active agents are pursued. As CLO inhibits DNA repair following exposure to DNA damaging agents, we designed a phase I study of the combination of CLO with CY. Methods: Pts ≥ 21 years (yrs) with primary refractory or relapsed ALL, NYHA class < 3, and a cardiac ejection fraction ≥ 45% were eligible. The continual reassessment method (CRM) was used to determine the maximum tolerated dose (MTD) from 4 pre-defined dose levels. The starting dose level was CLO 40 mg/m2 i.v. daily x 3d and CY 200 mg/m2 i.v. q12h x 3d. For cohort 2, CY was 300 mg/m2 and cohorts 3 and 4 maintained these doses with the treatment duration extended to 4 and 5 days, respectively. Results: Thirty pts have been enrolled. Median age was 28 yrs (range 21–72). Twenty-one pts had pre-B ALL, 5 pts pre-T/T ALL, 1 pt mature B ALL, and 3 pts biphenotypic acute leukemias. Karyotype was diploid in 10 pts and 2 pts had Ph+ ALL. Median number of prior regimens was 2 (1–5). Seven (23%) pts were primary refractory. Among the remainder, preceding median remission duration was 8.6 mos (1–39 mos). Five pts were treated in cohort 1 and 25 in cohort 2. One (20%) pt in cohort 1 and 9 (36%) in cohort 2 experienced DLTs (≥ grade 3) including transaminase elevations, diarrhea, hyperbilirubinemia, and (1 pt each) elevation of creatinine/renal failure, lipase elevation, rash, nausea/vomiting. Evaluable for response were 28 pts: 3 CR (one pt in cohort 1) and 1 marrow CR (OR 14%). All pts had pre-B ALL. One pt had Ph+ ALL, and one was primary refractory to HCVAD. Three early deaths due to infectious complications occurred (all in cohort 2). Conclusions: The MTD for this combination is CLO 40 mg/m2 i.v. daily x 3d and CY 200 mg/m2 i.v. q12h x 3d. DLT are mainly GI-related. A phase II extension is ongoing and will focus on efficacy data.

[Table: see text]

A phase II study with CP-4055 in patients with second salvage AML

7047

Background: CP-4055 (cytarabine 5'-elaidic acid ester) is a novel derivative of cytarabine, independent of nucleoside transporters to enter the cell. The aim of this study was to assess efficacy and safety of CP-4055 when given as second salvage therapy to patients (pts) with acute myeloid leukemia (AML). Methods: Adult pts who received two previous chemotherapy regimens and who had refractory/relapsed AML (CR after first salvage therapy lasting less than 6 months) were enrolled. CP-4055 2,000 mg/m2/d was administered over 24 h (CIV) in a day (d) 1–5 q3w schedule. After every 20-pts cohort, an Independent Data Monitoring Committee (IDMC) evaluated the results for futility and safety for recommendation of study continuation. Results: Forty pts (28 male and 12 female, median age 48 yrs [range 26–82]) were enrolled. 6 pts had previous transplant, the majority of the pts had previous ara-C based therapy, 12 pts had not obtained CR1 or CR2. Only 1 pt did not receive d1–5 dosing. The first 20-pt cohort (12 male, median age 53 yrs [range 26–82]) was evaluated by the IDMC. Most frequently reported related AE ≥ grade 3 (CTCAE v3.0) were myelosuppression, abdominal pain, colitis, diarrhoea, nausea, fatigue, liver function test (LFT) elevation. Clinical activity (IWG criteria for AML), 2 CR (1 with no CR1 or CR2), and 1 CRp (CR rate 15%), were reported. Toxicity was manageable, clinical activity reported and continuation recommended. Among all 40 patients 7 pts (18%) had LFT elevations of grade 3 or more and 4 pts (10%) had LFT elevations of grade 2. Clinical activity has been reported also among the last 20 pts. Therapy is ongoing. Conclusions: CP-4055 given as second salvage therapy to AML pts show manageable toxicity when administered at 2,000 mg/m2/d, 24 h CIV, in a d1–5 q3w schedule. Clinical activity (2 CR and 1 CRp) has been reported among the first 20 late stage AML pts. Data from 40 patients will be presented.

[Table: see text]

Alternatively spliced truncated BCR-ABL1 protein in CML patients with resistance to kinase inhibitors

7026

Background: We have reported that some patients with imatinib-resistant chronic myeloid leukemia (CML) express an alternatively spliced BCR-ABL mRNA with a 35-bp insertion (BCR-ABL135INS), resulting in the addition of 10 residues and truncation of 653 residues. Molecular dynamic simulation suggested that this truncation and insertion of new 10 AA results in structural changes similar to those seen in BCR-ABL with T315I mutation. Here we evaluate the prevalence of BCR-ABL135INS in imatinib-resistant CML, examine the effect of this mutation on resistance to compared the efficiency of various kinase inhibitors in vitro, and suggest a model for persistent CML and a possible strategy to eradicate residual disease. Methods: Using a sensitive PCR method, we determined the prevalence of the alternatively spliced BCR-ABL135INS mRNA in 288 patients with chronic-phase CML resistant to imatinib. Expression of truncated protein was confirmed by Western blot. We then tested the effectiveness of various kinase inhibitors on human K562 CML cells expressing different levels of BCR-ABL135INS along with wild-type BCR-ABL1. Results: BCR-ABL135INS mRNA was detected in 210 (73%) of the 288 patients. Only 25% of BCR-ABL135INS positive cases showed coexistance of ABL1 kinase point mutation. Immunoprecipitation studies demonstrated that expression of the predicted 143-kD BCR-ABL135INS protein at levels proportional to those predicted by mRNA. Expression of BCR-ABL135INS in K562 cells was sufficient to conferred resistance to imatinib, dasatinib, and nilotinib in a dose-dependant fashion. However, no resistance was detected using aurora kinase inhibitor (MK 0457) or homoharringtonine (HHT). BCR-ABL135INS suppressed imatinib, nilotinib, and dasatinib-mediated dephosphorylation of CRKL, LYN, SRC, and STAT5, but had no effect on MK 0457-mediated dephosphorylation. The combination of imatinib with nilotinib or HHT showed strong synergy, overcoming BCR-ABL135INS-induced resistance in vitro. Conclusions: These findings emphasize the importance of the overlooked alternatively spliced BCR-ABL135INS protein and may provide a strategy to treat resistant disease and eradicate residual CML.

No significant financial relationships to disclose.

All-optical memory based on the injection locking bistability of a two-color laser diode

We study the injection locking bistability of a specially engineered two-color semiconductor Fabry-Pérot laser. Oscillation in the uninjected primary mode leads to a bistability of single mode and two-color equilibria. With pulsed modulation of the injected power we demonstrate an all-optical memory element based on this bistability, where the uninjected primary mode is switched with 35 dB intensity contrast. Using experimental and theoretical analysis, we describe the associated bifurcation structure, which is not found in single mode systems with optical injection.

Gait kinematics of age-stratified hip replacement patients--a large scale, long-term follow-up study

Three-dimensional gait analysis data from 134 patients attending routine 10-year post-operative review clinics is presented. Patients were divided into five age groups-54-64 years, 65-69 years, 70-74 years, 75-79 years and over 80 years. A group of 10 normal elderly subjects was also tested. All age groups displayed reduced range of hip flexion/extension, range of knee flexion extension, maximum hip extension and range of hip abduction/adduction and reduced velocity and step length compared to the normal elderly group. However, there was no difference in gait kinematics between the age groups. Patients over 80 years of age displayed significantly reduced range of sagittal plane ankle motion, but this is unlikely to be secondary to hip joint restriction and more likely due to reduced walking speed associated with very elderly subjects. This study reveals that even the youngest hip replacement patients do not attain normal gait kinematics 10-year post-operatively and that muscle atrophy and residual stiffness may influence patient kinematics many years post-operation.

Prevalence and molecular characterization of Escherichia coli O157:H7 on Irish lamb carcasses, fleece and in faeces samples

AIMS

To determine the prevalence, seasonal variation and virulence characteristics of Escherichia coli O157:H7 in lambs presented for slaughter in Ireland.

METHODS AND RESULTS

Over a 13-month period, pre- and postchill carcass swabs, faeces and fleece samples from 1600 lambs were examined for the presence of E. coli O157:H7. Escherichia coli O157:H7 was isolated from 5.75% (23/400) of fleece samples, 1.5% (6/400) of pre- and 1% (4/400) of postchill carcass swabs but was not isolated in faeces (0/400). The present study detected no evidence of seasonal variation. Polymerase chain reaction analysis showed that both the vt1 and vt2 genes associated with clinical illness were carried by five of the E. coli O157:H7 isolates, while 24 of the remaining isolates carried the vt2 gene only. Phage typing detected four different subtypes: PT 32 (48.48%), PT 8 (12.12%), PT 31 (12.12%) and PT 21/28 (12.12%).

CONCLUSIONS

Escherichia coli O157:H7 is present in lambs at slaughter in Irish abattoirs and the virulence profiles of these isolates reveals that they are potentially harmful to humans.

SIGNIFICANCE AND IMPACT OF THE STUDY

The present study provides crucial information indicating that sheep may be a significant contributing source to human E. coli O157:H7 infection.

The use of a posterior lip augmentation device for a revision of recurrent dislocation after primary cemented Charnley/Charnley Elite total hip replacement: results at a mean follow-up of six years and nine months

Between April 1992 and July 2005, 310 posterior lip augmentation devices were used for the treatment of recurrent dislocation of the hip in 307 patients who had received primary total hip replacements (THRs) using Charnley/Charnley Elite components with a cemented acetabulum. The mean number of dislocations before stabilisation with the device was five (1 to 16) with a mean time to this intervention from the first dislocation of 3.8 years (0 days to 22.5 years). The mean age of the patients at this reconstruction was 75.4 years (39 to 96). A retrospective clinical and radiological review was carried out at a mean follow-up of six years and nine months (4.4 months to 13 years and 7 months). Of the 307 patients, 53 had died at the time of the latest review, with a functioning THR and with the posterior lip augmentation device in situ. There were four revisions (1.3%), one for pain, two for deep infection and one for loosening of the acetabular component. Radiolucent lines around the acetabular component increased in only six cases after insertion of the device which was successful in eliminating instability in 302 patients, with only five further dislocations (1.6%) occurring after its insertion.