Association of Autologous Tumor Lysate-Loaded Dendritic Cell Vaccination With Extension of Survival Among Patients With Newly Diagnosed and Recurrent Glioblastoma: A Phase 3 Prospective Externally Controlled Cohort Trial.

Importance: Glioblastoma is the most lethal primary brain cancer. Clinical outcomes for glioblastoma remain poor, and new treatments are needed. Objective: To investigate whether adding autologous tumor lysate-loaded dendritic cell vaccine (DCVax-L) to standard of care (SOC) extends survival among patients with glioblastoma. Design, Setting, and Participants: This phase 3, prospective, externally controlled nonrandomized trial compared overall survival (OS) in patients with newly diagnosed glioblastoma (nGBM) and recurrent glioblastoma (rGBM) treated with DCVax-L plus SOC vs contemporaneous matched external control patients treated with SOC. This international, multicenter trial was conducted at 94 sites in 4 countries from August 2007 to November 2015. Data analysis was conducted from October 2020 to September 2021. Interventions: The active treatment was DCVax-L plus SOC temozolomide. The nGBM external control patients received SOC temozolomide and placebo; the rGBM external controls received approved rGBM therapies. Main Outcomes and Measures: The primary and secondary end points compared overall survival (OS) in nGBM and rGBM, respectively, with contemporaneous matched external control populations from the control groups of other formal randomized clinical trials. Results: A total of 331 patients were enrolled in the trial, with 232 randomized to the DCVax-L group and 99 to the placebo group. Median OS (mOS) for the 232 patients with nGBM receiving DCVax-L was 19.3 (95% CI, 17.5-21.3) months from randomization (22.4 months from surgery) vs 16.5 (95% CI, 16.0-17.5) months from randomization in control patients (HR = 0.80; 98% CI, 0.00-0.94; P = .002). Survival at 48 months from randomization was 15.7% vs 9.9%, and at 60 months, it was 13.0% vs 5.7%. For 64 patients with rGBM receiving DCVax-L, mOS was 13.2 (95% CI, 9.7-16.8) months from relapse vs 7.8 (95% CI, 7.2-8.2) months among control patients (HR, 0.58; 98% CI, 0.00-0.76; P < .001). Survival at 24 and 30 months after recurrence was 20.7% vs 9.6% and 11.1% vs 5.1%, respectively. Survival was improved in patients with nGBM with methylated MGMT receiving DCVax-L compared with external control patients (HR, 0.74; 98% CI, 0.55-1.00; P = .03). Conclusions and Relevance: In this study, adding DCVax-L to SOC resulted in clinically meaningful and statistically significant extension of survival for patients with both nGBM and rGBM compared with contemporaneous, matched external controls who received SOC alone. Trial Registration: ClinicalTrials.gov Identifier: NCT00045968.

Launching the Quality Outcomes Database Tumor Registry: rationale, development, and pilot data.

OBJECTIVE: Neurosurgeons generate an enormous amount of data daily. Within these data lie rigorous, valid, and reproducible evidence. Such evidence can facilitate healthcare reform and improve quality of care. To measure the quality of care provided objectively, evaluating the safety and efficacy of clinical activities should occur in real time. Registries must be constructed and collected data analyzed with the precision akin to that of randomized clinical trials to accomplish this goal. METHODS: The Quality Outcomes Database (QOD) Tumor Registry was launched in February 2019 with 8 sites in its initial 1-year pilot phase. The Tumor Registry was proposed by the AANS/CNS Tumor Section and approved by the QOD Scientific Committee in the fall of 2018. The initial pilot phase aimed to assess the feasibility of collecting outcomes data from 8 academic practices across the United States; these outcomes included length of stay, discharge disposition, and inpatient complications. RESULTS: As of November 2019, 923 eligible patients have been entered, with the following subsets: intracranial metastasis (17.3%, n = 160), high-grade glioma (18.5%, n = 171), low-grade glioma (6%, n = 55), meningioma (20%, n = 184), pituitary tumor (14.3%, n = 132), and other intracranial tumor (24%, n = 221). CONCLUSIONS: The authors have demonstrated here, as a pilot study, the feasibility of documenting demographic, clinical, operative, and patient-reported outcome characteristics longitudinally for 6 common intracranial tumor types.

Organized Hematoma of the Sphenoid Sinus With Acute Blindness: Insight Into Pathogenesis of Disease.

Sinonasal organized hematomas (OHs) are rare lesions that primarily localize to the maxillary sinus. The rate of growth of these masses has not been described in the literature. We present a case of a 59-year-old gentleman with polyostotic fibrous dysplasia who presented with acute loss of vision in the left eye from an expanding OH of the sphenoid sinusitis. After expanded endonasal, transpterygoid approach and debulking, patient experienced significant vision improvement. Close follow-up imaging preoperatively allowed radiologic documentation of the rate of OH growth and this is presented in detail.

Correction to: First results on survival from a large Phase 3 clinical trial of an autologous dendritic cell vaccine in newly diagnosed glioblastoma.

Following publication of the original article [1], the authors reported an error in the spelling of one of the author names. In this Correction the incorrect and correct author names are indicated and the author name has been updated in the original publication. The authors also reported an error in the Methods section of the original article. In this Correction the incorrect and correct versions of the affected sentence are indicated. The original article has not been updated with regards to the error in the Methods section.

First results on survival from a large Phase 3 clinical trial of an autologous dendritic cell vaccine in newly diagnosed glioblastoma.

BACKGROUND: Standard therapy for glioblastoma includes surgery, radiotherapy, and temozolomide. This Phase 3 trial evaluates the addition of an autologous tumor lysate-pulsed dendritic cell vaccine (DCVax®-L) to standard therapy for newly diagnosed glioblastoma. METHODS: After surgery and chemoradiotherapy, patients were randomized (2:1) to receive temozolomide plus DCVax-L (n = 232) or temozolomide and placebo (n = 99). Following recurrence, all patients were allowed to receive DCVax-L, without unblinding. The primary endpoint was progression free survival (PFS); the secondary endpoint was overall survival (OS). RESULTS: For the intent-to-treat (ITT) population (n = 331), median OS (mOS) was 23.1 months from surgery. Because of the cross-over trial design, nearly 90% of the ITT population received DCVax-L. For patients with methylated MGMT (n = 131), mOS was 34.7 months from surgery, with a 3-year survival of 46.4%. As of this analysis, 223 patients are ≥ 30 months past their surgery date; 67 of these (30.0%) have lived ≥ 30 months and have a Kaplan-Meier (KM)-derived mOS of 46.5 months. 182 patients are ≥ 36 months past surgery; 44 of these (24.2%) have lived ≥ 36 months and have a KM-derived mOS of 88.2 months. A population of extended survivors (n = 100) with mOS of 40.5 months, not explained by known prognostic factors, will be analyzed further. Only 2.1% of ITT patients (n = 7) had a grade 3 or 4 adverse event that was deemed at least possibly related to the vaccine. Overall adverse events with DCVax were comparable to standard therapy alone. CONCLUSIONS: Addition of DCVax-L to standard therapy is feasible and safe in glioblastoma patients, and may extend survival. Trial registration Funded by Northwest Biotherapeutics; Clinicaltrials.gov number: NCT00045968; https://clinicaltrials.gov/ct2/show/NCT00045968?term=NCT00045968&rank=1 ; initially registered 19 September 2002.

The transplanum transtuberculum approaches for suprasellar and sellar-suprasellar lesions: avoidance of cerebrospinal fluid leak and lessons learned.

OBJECTIVE: To present a large series of patients and examine the learning curve of the endonasal endoscopic transplanum, transtuberculum approach for primarily suprasellar or sellar-suprasellar tumors. METHODS: We identified 122 patients who underwent 126 surgeries using the transplanum, transtuberculum approach. Extent of resection was determined with volumetric analysis of magnetic resonance imagings. Results concerning vision, endocrine function, and complications were noted. RESULTS: Average tumor volume was 14 cm(3). The most frequent pathologies were pituitary macroadenoma (51.6%), craniopharyngioma (20.6%), and meningioma (15.9%). A total of 73% patients presented with visual compromise. Rates of gross total resection (GTR) and near total resection for the group as a whole were 58.1% and 13.7%, and for the patients in whom GTR was intended (n = 90), rates of GTR and near total resection were 77.5% and 12.5% for a total of 90%. Extent of resection in this group was 97.6%. Vision improved in 52.4% and deteriorated in 4.8%. Favorable endocrine outcome occurred in 63.5%. The cerebrospinal fluid leak rate was 3.1% for the series as a whole. It improved from 6.3% in the first half of the series to 0 in the second half. Leak rates varied with technique from 11% (fat graft only) to 4.2% (gasket seal only) to 1.8% (fat plus nasoseptal flap) to 0 (gasket plus nasoseptal flap). The rate of other complications was 14.3% in the first half of the series and 1.6% in the second half. There was one infection (0.8%). CONCLUSIONS: The endonasal endoscopic transtuberculum transplanum approach is a safe and effective minimal access approach to midline pathology in the suprasellar cistern.

Efficacy of gamma knife radiosurgery for small-volume recurrent malignant gliomas after initial radical resection.

OBJECTIVE: To review the authors' experience with Gamma Knife radiosurgery (GKR) for small recurrent high-grade gliomas (HGGs) following prior radical resection, external-beam radiation therapy (EBRT), and chemotherapy with temozolomide (TMZ). METHODS: The authors retrospectively analyzed 26 consecutive adults (9 women and 17 men; median age 60.4 years; Karnofsky Performance Status [KPS]≥70) who underwent GKR for recurrent HGGs from 2004-2009. Median lesion volume was 1.22 cc, and median treatment dose was 15 Gy. Pathology included glioblastoma multiforme (GBM; n=16), anaplastic astrocytoma (AA; n=5), and anaplastic mixed oligoastrocytoma (AMOA; n=5). Two patients lost to follow-up were excluded from radiographic outcome analyses. RESULTS: Median overall survival (OS) for the entire cohort from the time of GKR was 13.5 months. Values for 12-month actuarial survival from time of GKR for GBM, AMOA, and AA were 37%, 20% and 80%. Local failure occurred in 9 patients (37.5%) at a median time of 5.8 months, and 18 patients (75%) experienced distant progression at a median of 4.8 months. Complications included radiation necrosis in two patients and transient worsening of hemiparesis in one patient. Multivariate hazard ratio (HR) analysis showed KPS 90 or greater, smaller tumor volumes, and increased time to recurrence after resection to be associated with longer OS following GKR. CONCLUSIONS: GKR provided good local tumor control in this group of clinically stable and predominantly high-functioning patients with small recurrent HGGs after radical resection. Meaningful survival times after GKR were seen. GKR can be considered for selected patients with recurrent HGGs.

Bilateral invasive electroencephalography in patients with tuberous sclerosis complex: a path to surgery?

OBJECT: Many children with epilepsy and tuberous sclerosis complex (TSC) have multiple tubers on MR imaging and poorly localized/lateralized video electroencephalography (EEG) findings. Given the long-term risks associated with frequent seizures and multiple antiepileptic drugs, along with improved success in identifying focal epileptogenic zones in patients with multifocal lesions, the authors used bilateral intracranial EEG to lateralize the epileptogenic zone in patients with nonlateralizable noninvasive preoperative evaluations. METHODS: A retrospective analysis from January 1, 1998, to June 30, 2008, identified 62 children with TSC who were presented at a surgical conference. Of the 52 patients undergoing diagnostic or therapeutic procedures during the study period, 20 underwent bilateral intracranial EEG. The presurgical testing results, intracranial EEG findings, surgical interventions, and outcomes were reviewed. RESULTS: Fourteen of 20 patients had intracranial EEG findings consistent with a resectable epileptogenic zone. One patient is awaiting further resection. Five patients had findings consistent with a nonresectable epileptogenic zone, and 1 of these patients underwent a callosotomy. Seven patients had Engel Class I outcomes, 1 was Class II, 3 were Class III, and 3 were Class IV (mean follow-up 25 months). CONCLUSIONS: Bilateral intracranial EEG can identify potential resectable seizure foci in nonlateralizable epilepsy in TSC. Although 6 of 20 patients did not undergo resection (1 patient is pending future resection), significant improvements in seizures (Engel Class I or II) were noted in 8 patients. In the authors' experience, this invasive monitoring provided a safe method for identifying the ictal onset zone.

Do tubers contain function? Resection of epileptogenic foci in perirolandic cortex in children with tuberous sclerosis complex.

PURPOSE: Surgical resection of single, dominant, epileptogenic lesions in patients with tuberous sclerosis complex (TSC) is now accepted as an effective therapy. However, patients with symptomatic tubers in eloquent cortex are sometimes not offered surgery because of the concern for postoperative neurologic morbidity. In this study, we examine our results in children undergoing surgery for resection of tubers and associated seizure foci in rolandic and perirolandic cortex. METHODS: Between 1998 and 2008, 52 pediatric patients (mean age 4 years) with TSC underwent epilepsy surgery at the NYU Comprehensive Epilepsy Center. Fifteen of these patients underwent multistage surgery for invasive mapping of seizure foci and surrounding functional cortex followed by resection of tubers/seizure foci in or near rolandic cortex. Data were retrospectively collected and neurologic outcomes were tabulated. RESULTS: Postoperatively, four patients (27%) had either new hemiparesis or worsening of a preexisting hemiparesis. However, all patients were back to their neurologic baselines at 3-month follow-up, yielding no permanent postoperative deficits. The modified Engel outcome was class I in nine patients (60%), class II in three patients (20%), class III in two patients (13%), and class IV in one patient (7%) after 40 months mean follow-up. DISCUSSION: Surgical resection of tubers and associated epileptogenic foci in rolandic and perirolandic cortex in children with TSC is feasible, with low neurologic morbidity, and yields good seizure control. These results suggest that tubers and perituberal epileptogenic foci can be safely resected even in eloquent regions because of reorganization of functional cortex or because these lesions contain no neurologic function.

Role of diffusion tensor imaging in resection of thalamic juvenile pilocytic astrocytoma.

OBJECT: The choice of surgical approach during resection of a thalamic juvenile pilocytic astrocytoma (JPA) is dictated by the location of the displaced normal thalamus and posterior limb of the internal capsule (PLIC). Diffusion tensor (DT) imaging and white matter tractography can identify the location of the PLIC in relation to the tumor and may be useful in planning the operative trajectory. METHODS: Diffusion tensor imaging was used to localize the PLIC on preoperative MR imaging in 6 children undergoing resection of thalamic JPAs. After review of the standard T2-weighted MR imaging sequences, the anticipated position of the PLIC was determined. This result was compared with the location of the PLIC determined by a blinded radiologist with the use of DT imaging. The utility of DT imaging in determining the surgical approach to a thalamic JPA, degree of resection, and neurological outcomes were all evaluated. RESULTS: Diffusion tensor imaging confirmed the expected location of the PLIC as approximated on conventional T2-weighted images in all 6 cases. In 1 patient in particular, unexpected medial deviation of the PLIC was identified, and this proved useful in tailoring the approach to a more lateral trajectory. Gross-total resection of all cystic and solid tumor components was confirmed on postoperative imaging in all cases. All patients experienced mild to moderate worsening of neurological status immediately following resection, but 4 of 6 patients were back to their preoperative baseline at 6-month follow-up. CONCLUSIONS: Diffusion tensor imaging and white matter tractography successfully identified the white matter fibers emanating from the precentral gyrus within the PLIC in children with thalamic JPAs prior to surgery. Diffusion tensor imaging served as a valuable tool for stereotactic planning of operative approaches to thalamic JPAs. Localizing the position of the PLIC helped minimize potential neurological morbidity and facilitated gross-total resection.

Refractory epilepsy in tuberous sclerosis: vagus nerve stimulation with or without subsequent resective surgery.

OBJECTIVE: The goal of the work described here was to assess the efficacy and safety of vagus nerve stimulation in a cohort of patients with tuberous sclerosis complex with refractory epilepsy. Furthermore, we examined the impact of vagus nerve stimulation failure on the ultimate outcome following subsequent intracranial epilepsy surgery. METHODS: A retrospective review was performed on 19 patients with refractory epilepsy and TSC who underwent vagus nerve stimulator (VNS) implantation. There were 11 (58%) females and 8 (42%) males aged 2 to 44 years when the VNS was implanted (mean: 14.7+/-12 years). Twelve patients underwent primary VNS implantation after having failed a mean of 7.1 antiepileptic drugs. Two patients (17%) had generalized epilepsy, one had a single seizure focus, three (25%) had multifocal epilepsy, and six (50%) had multifocal and generalized epilepsy. Seven patients were referred for device removal and evaluation for intracranial procedures. One patient in the primary implantation group was lost to follow-up and excluded from outcome analysis. RESULTS: All implantations and removals were performed without permanent complications. The duration of treatment for primary VNS implants varied from 8.5 months to 9.6 years (mean: 4.9 years). Mean seizure frequency significantly improved following VNS implantation (mean reduction: 72%, P<0.002). Two patients had Engel Class I (18%), one had Class II (9%), seven had Class III (64%), and one had Class IV (9%) outcome. Three patients with poor response to vagus nerve stimulation therapy at our center underwent resection of one or more seizure foci (Engel Class I, two patients; Engel Class III, one patient). Seven patients referred to our center for VNS removal and craniotomy underwent seizure focus resection (6) or corpus callosotomy (1) (Engel Class II: 2, Engel III: 2; Engel IV: 3). In total, 8 of 10 (80%) patients experienced improved seizure control following intracranial surgery (mean reduction: 65%, range: 0-100%, P<0.05). CONCLUSIONS: VNS is a safe and effective treatment option for medically refractory epilepsy in patients with tuberous sclerosis complex. Nine of 11 patients (82%) experienced at least a 67% reduction in seizure burden. Lack of response to vagus nerve stimulation does not preclude subsequent improvement in seizure burden with intracranial epilepsy surgery.

Surgical treatment of ectopic recurrence of craniopharyngioma. Report of 4 cases.

Local recurrence following radical resection is one of the most common complications of pediatric craniopharyngioma. Only 28 cases of ectopic recurrence of craniopharyngioma have been reported in the literature, and only 13 cases occurred in patients originally treated as children. In this consecutive series of 86 children who underwent radical resection of primary and recurrent craniopharyngiomas, 4 patients (4.7%) experienced ectopic tumor recurrence, accounting for 27% of all recurrences after gross-total resection. The authors report on the successful surgical treatment of these 4 patients and the impact of ectopic craniopharyngioma recurrence on survival.

Minimal residual calcification and recurrence after gross-total resection of craniopharyngioma in children.

OBJECT: The purpose of this study was to assess the impact of minimal residual calcification without enhancing tumor on the rate of recurrence after gross-total resection (GTR) of craniopharyngioma in children. METHODS: Data were retrospectively collected in 86 patients younger than 21 years of age in whom 103 craniopharyngioma resections were performed by the senior author between 1986 and 2008. Forty-nine patients (27 boys and 22 girls, with a mean age of 8.6 years) fulfilled the criteria for inclusion in this study by having tumor calcification on the preoperative CT scan, undergoing GTR, and having complete postoperative CT and MR imaging and clinical follow-up. RESULTS: Thirteen patients (27%) had residual calcification (< or = 2 mm in 12 patients; 3.5 mm in 1 patient) on their postoperative CT scan. At a mean follow-up of 9.4 years (median 10 years), 2 (15%) of 13 patients with and 10 (28%) of 36 patients without residual calcification experienced tumor recurrence. There were no significant differences between these groups in terms of the duration of follow-up, time to recurrence, rate of recurrence, or recurrence-free survival. CONCLUSIONS: The absence or presence of minimal residual calcification does not have an impact on the risk of recurrence after GTR in pediatric craniopharyngiomas. The authors recommend withholding irradiation or other adjuvant therapy in the setting of minimal residual calcification without enhancing tumor. Close follow-up with frequent serial imaging in all patients after GTR is imperative to identify and treat early recurrence.

Resection of insular gliomas: the importance of lenticulostriate artery position.

OBJECT: The object of this study was to identify characteristic preoperative angiographic and MR imaging features of safely resectable insular gliomas and describe the surgical techniques and postoperative clinical outcomes. METHODS: Thirty-eight patients with insular gliomas underwent transsylvian resection between 1995 and 2007. Patient demographics, presenting symptoms, pathological findings, and neurological outcomes were retrospectively reviewed. Preoperative MR imaging-defined tumor volumes were superimposed onto the preoperative stereotactic cerebral angiograms to determine whether the insular tumor was confined lateral to (Group I) or extended medially around (Group II) the lenticulostriate arteries (LSAs). RESULTS: Twenty-five patients (66%) had tumors situated lateral to the LSAs and 13 (34%) had tumors encasing the LSAs. Insular gliomas situated lateral to the LSAs led to significant medial displacement of these vessels (161 +/- 39%). In 20 (80%) of these 25 cases the boundaries between tumor and brain parenchyma were well demarcated on preoperative T2-weighted MR images. In contrast, there was less displacement of the LSAs (130 +/- 14%) in patients with insular gliomas extending around the LSAs on angiography. In 11 (85%) of these 13 cases, the tumor boundaries were diffuse on T2-weighted MR images. Postoperative hemiparesis or worsening of a preexisting hemiparesis, secondary to LSA compromise, occurred in 5 patients, all of whom had tumor volumes that extended medial to the LSAs. Gross-total or near-total resection was achieved more frequently in cases in which the insular glioma remained lateral to the LSAs (84 vs 54%). CONCLUSIONS: Insular gliomas with an MR imaging-defined tumor volume located lateral to the LSAs on stereotactic angiography displace the LSAs medially by expanding the insula, have well-demarcated tumor boundaries on MR images, and can be completely resected with minimal neurological morbidity. In contrast, insular tumors that appear to surround the LSAs do not displace these vessels medially, are poorly demarcated from normal brain parenchyma on MR images, and are associated with higher rates of neurological morbidity if aggressive resection is pursued. Preoperative identification of these anatomical growth patterns can be of value in planning resection.

Stereotactic volumetric resection of thalamic pilocytic astrocytomas.

OBJECTIVE: To describe the surgical approaches, the radiographic and clinical outcomes, and the long-term follow-up of patients harboring thalamic pilocytic astrocytomas after radical resection by means of a stereotactic volumetric technique. METHODS: Seventy-two patients with thalamic pilocytic astrocytomas underwent stereotactic volumetric resection by the senior author (PJK) at the Mayo Clinic between 1984 and 1993 (44 patients) and at New York University Medical Center between 1993 and 2005 (28 patients). Patient demographics, presenting symptoms, surgical approaches, neurological outcomes, pathology, initial postoperative status, and long-term clinical and radiographic follow-up were retrospectively reviewed. RESULTS: On preoperative neurological examinations, 54 of the 72 patients had neurological deficits; of these, 48 had hemiparesis. Postoperative imaging demonstrated gross total resection in 58 patients and minimal (<6 mm) residual tumor in 13 patients. Tumor resection was aborted in one patient. On immediate postoperative examination, 16 patients had significant improvements in hemiparesis. Six patients had worsening of a preexisting hemiparesis and one had a new transient postoperative hemiparesis. There was one postoperative death. After 13 to 20 years of follow-up in the Mayo group (mean, 15 +/- 3 yr) and 1 to 13 years of follow-up in the New York University group (mean, 8 +/- 3 yr), 67 patients were recurrence/progression-free, one had tumor recurrence, and three had progression of residual tumor. There were two shunt-related deaths. On long-term neurological follow-up, 27 patients had significant improvements in hemiparesis; one patient with a postoperative worsening of a preexisting hemiparesis remained unchanged. There were no patients with new long-term motor deficits after stereotactic resection. CONCLUSION: Gross total removal of thalamic pilocytic astrocytomas with low morbidity and mortality can be achieved by computer-assisted stereotactic volumetric resection techniques. Gross total resection of these lesions confers a favorable long-term prognosis without adjuvant chemotherapy and/or radiation therapy and leads to the improvement of neurological deficits.

Inhibition of NF-kappa-B cellular function via specific targeting of the I-kappa-B-ubiquitin ligase.

Activation of the transcription factor NF-kappa B is a paradigm for signal transduction through the ubiquitin-proteasome pathway: ubiquitin-dependent degradation of the transcriptional inhibitor I kappa B in response to cell stimulation. A major issue in this context is the nature of the recognition signal and the targeting enzyme involved in the proteolytic process. Here we show that following a stimulus-dependent phosphorylation, and while associated with NF-kappa B, I kappa B is targeted by a specific ubiquitin-ligase via direct recognition of the signal-dependent phosphorylation site; phosphopeptides corresponding to this site specifically inhibit ubiquitin conjugation of I kappa B and its subsequent degradation. The ligase recognition signal is functionally conserved between I kappa B alpha and I kappa B beta, and does not involve the nearby ubiquitination site. Microinjection of the inhibitory peptides into stimulated cells abolished NF-kappa B activation in response to TNF alpha and the consequent expression of E-selectin, an NF-kappa B-dependent cell-adhesion molecule. Inhibition of NF-kappa B function by specific blocking of ubiquitin ligase activity provides a novel approach for intervening in cellular processes via regulation of unique proteolytic events.

Stimulation-dependent I kappa B alpha phosphorylation marks the NF-kappa B inhibitor for degradation via the ubiquitin-proteasome pathway.

The nuclear translocation of NF-kappa B follows the degradation of its inhibitor, I kappa B alpha, an event coupled with stimulation-dependent inhibitor phosphorylation. Prevention of the stimulation-dependent phosphorylation of I kappa B alpha, either by treating cells with various reagents or by mutagenesis of certain putative I kappa B alpha phosphorylation sites, abolishes the inducible degradation of I kappa B alpha. Yet, the mechanism coupling the stimulation-induced phosphorylation with the degradation has not been resolved. Recent reports suggest a role for the proteasome in I kappa B alpha degradation, but the mode of substrate recognition and the involvement of ubiquitin conjugation as a targeting signal have not been addressed. We show that of the two forms of I kappa B alpha recovered from stimulated cells in a complex with RelA and p50, only the newly phosphorylated form, pI kappa B alpha, is a substrate for an in vitro reconstituted ubiquitin-proteasome system. Proteolysis requires ATP, ubiquitin, a specific ubiquitin-conjugating enzyme, and other ubiquitin-proteasome components. In vivo, inducible I kappa B alpha degradation requires a functional ubiquitin-activating enzyme and is associated with the appearance of high molecular weight adducts of I kappa B alpha. Ubiquitin-mediated protein degradation may, therefore, constitute an integral step of a signal transduction process.