High-dose immunosuppressive therapy and autologous HCT for relapsing-remitting MS.

OBJECTIVE: To evaluate the safety, efficacy, and durability of multiple sclerosis (MS) disease stabilization after high-dose immunosuppressive therapy (HDIT) and autologous hematopoietic cell transplantation (HCT). METHODS: High-Dose Immunosuppression and Autologous Transplantation for Multiple Sclerosis (HALT-MS) is a phase II clinical trial of HDIT/HCT for patients with relapsing-remitting (RR) MS who experienced relapses with disability progression (Expanded Disability Status Scale [EDSS] 3.0-5.5) while on MS disease-modifying therapy. The primary endpoint was event-free survival (EFS), defined as survival without death or disease activity from any one of: disability progression, relapse, or new lesions on MRI. Participants were evaluated through 5 years posttransplant. Toxicities were reported using the National Cancer Institute Common Terminology Criteria for Adverse Events (AE). RESULTS: Twenty-five participants were evaluated for transplant and 24 participants underwent HDIT/HCT. Median follow-up was 62 months (range 12-72). EFS was 69.2% (90% confidence interval [CI] 50.2-82.1). Progression-free survival, clinical relapse-free survival, and MRI activity-free survival were 91.3% (90% CI 74.7%-97.2%), 86.9% (90% CI 69.5%-94.7%), and 86.3% (90% CI 68.1%-94.5%), respectively. AE due to HDIT/HCT were consistent with expected toxicities and there were no significant late neurologic adverse effects noted. Improvements were noted in neurologic disability with a median change in EDSS of -0.5 (interquartile range -1.5 to 0.0; p = 0.001) among participants who survived and completed the study. CONCLUSION: HDIT/HCT without maintenance therapy was effective for inducing long-term sustained remissions of active RRMS at 5 years. CLINICALTRIALSGOV IDENTIFIER: NCT00288626. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that participants with RRMS experienced sustained remissions with toxicities as expected from HDIT/HCT.

Establishment of HSV1 latency in immunodeficient mice facilitates efficient in vivo reactivation.

The establishment of latent infections in sensory neurons is a remarkably effective immune evasion strategy that accounts for the widespread dissemination of life long Herpes Simplex Virus type 1 (HSV1) infections in humans. Periodic reactivation of latent virus results in asymptomatic shedding and transmission of HSV1 or recurrent disease that is usually mild but can be severe. An in-depth understanding of the mechanisms regulating the maintenance of latency and reactivation are essential for developing new approaches to block reactivation. However, the lack of a reliable mouse model that supports efficient in vivo reactivation (IVR) resulting in production of infectious HSV1 and/or disease has hampered progress. Since HSV1 reactivation is enhanced in immunosuppressed hosts, we exploited the antiviral and immunomodulatory activities of IVIG (intravenous immunoglobulins) to promote survival of latently infected immunodeficient Rag mice. Latently infected Rag mice derived by high dose (HD), but not low dose (LD), HSV1 inoculation exhibited spontaneous reactivation. Following hyperthermia stress (HS), the majority of HD inoculated mice developed HSV1 encephalitis (HSE) rapidly and synchronously, whereas for LD inoculated mice reactivated HSV1 persisted only transiently in trigeminal ganglia (Tg). T cells, but not B cells, were required to suppress spontaneous reactivation in HD inoculated latently infected mice. Transfer of HSV1 memory but not OVA specific or naïve T cells prior to HS blocked IVR, revealing the utility of this powerful Rag latency model for studying immune mechanisms involved in control of reactivation. Crossing Rag mice to various knockout strains and infecting them with wild type or mutant HSV1 strains is expected to provide novel insights into the role of specific cellular and viral genes in reactivation, thereby facilitating identification of new targets with the potential to block reactivation.

High-dose immunosuppressive therapy and autologous hematopoietic cell transplantation for relapsing-remitting multiple sclerosis (HALT-MS): a 3-year interim report.

IMPORTANCE: Most patients with relapsing-remitting (RR) multiple sclerosis (MS) who receive approved disease-modifying therapies experience breakthrough disease and accumulate neurologic disability. High-dose immunosuppressive therapy (HDIT) with autologous hematopoietic cell transplant (HCT) may, in contrast, induce sustained remissions in early MS. OBJECTIVE: To evaluate the safety, efficacy, and durability of MS disease stabilization through 3 years after HDIT/HCT. DESIGN, SETTING, AND PARTICIPANTS: Hematopoietic Cell Transplantation for Relapsing-Remitting Multiple Sclerosis (HALT-MS) is an ongoing, multicenter, single-arm, phase 2 clinical trial of HDIT/HCT for patients with RRMS who experienced relapses with loss of neurologic function while receiving disease-modifying therapies during the 18 months before enrolling. Participants are evaluated through 5 years after HCT. This report is a prespecified, 3-year interim analysis of the trial. Thirty-six patients with RRMS from referral centers were screened; 25 were enrolled. INTERVENTIONS: Autologous peripheral blood stem cell grafts were CD34+ selected; the participants then received high-dose treatment with carmustine, etoposide, cytarabine, and melphalan as well as rabbit antithymocyte globulin before autologous HCT. MAIN OUTCOMES AND MEASURES: The primary end point of HALT-MS is event-free survival defined as survival without death or disease activity from any one of the following outcomes: (1) confirmed loss of neurologic function, (2) clinical relapse, or (3) new lesions observed on magnetic resonance imaging. Toxic effects are reported using National Cancer Institute Common Terminology Criteria for Adverse Events. RESULTS: Grafts were collected from 25 patients, and 24 of these individuals received HDIT/HCT. The median follow-up period was 186 weeks (interquartile range, 176-250) weeks). Overall event-free survival was 78.4% (90% CI, 60.1%-89.0%) at 3 years. Progression-free survival and clinical relapse-free survival were 90.9% (90% CI, 73.7%-97.1%) and 86.3% (90% CI, 68.1%-94.5%), respectively, at 3 years. Adverse events were consistent with expected toxic effects associated with HDIT/HCT, and no acute treatment-related neurologic adverse events were observed. Improvements were noted in neurologic disability, quality-of-life, and functional scores. CONCLUSIONS AND RELEVANCE: At 3 years, HDIT/HCT without maintenance therapy was effective for inducing sustained remission of active RRMS and was associated with improvements in neurologic function. Treatment was associated with few serious early complications or unexpected adverse events.

The case for immunomodulatory approaches in treating HSV encephalitis.

HSV encephalitis (HSE) is the most prevalent sporadic viral encephalitis. Although safe and effective antiviral therapies and greatly improved noninvasive diagnostic procedures have significantly improved outcomes, mortality (~20%) and debilitating neurological sequelae in survivors remain unacceptably high. An encouraging new development is that the focus is now shifting away from the virus exclusively, to include consideration of the host immune response to infection in the pathology underlying development of HSE. In this article, the authors discuss results from recent studies in experimental mouse models, as well as clinical reports that demonstrate a role for exaggerated host inflammatory responses in the brain in the development of HSE that is motivating researchers and clinicians to consider new therapeutic approaches for treating HSE. The authors also discuss results from a few studies that have shown that immunomodulatory drugs can be highly protective against HSE, which supports a role for deleterious host inflammatory responses in HSE. The impressive outcomes of some immunomodulatory approaches in mouse models of HSE emphasize the urgent need for clinical trials to rigorously evaluate combination antiviral and immunomodulatory therapy in comparison with standard antiviral therapy for treatment of HSE, and support for such an initiative is gaining momentum.

Predicting acute and persistent neuropathy associated with oxaliplatin.

OBJECTIVES: We sought to predict oxaliplatin-associated peripheral neuropathy during modified FOLFOX6 (mFOLFOX6) therapy. METHODS: Equal numbers of male and female patients with previously untreated, primary or recurrent colorectal cancer were followed through a first course of mFOLFOX6 with 85 mg/m² oxaliplatin every 2 weeks. Accounting for correlation among a subject's cycle, logistic regression estimated per cycle risk of acute (under 14 d) and persistent (14 d or more) neuropathy. Proportional hazards regression predicted time to persistent neuropathy. RESULTS: Among mFOLFOX6 recipients (n = 50, age 58.9 ± 10.1 y), 36% received concomitant bevacizumab. Of the total number of cycles, 94.2% (422/448) were evaluable. Most (84%) subjects reported neuropathy at least once; 74% reported acute and 48% reported persistent symptoms. On multivariate analysis, risk factors shared by acute and persistent neuropathy were body surface area >2.0, acute neuropathy in a past cycle, and lower body weight. In addition, risk of acute neuropathy decreased with age (adjusted for renal function and winter season), whereas risk of persistent neuropathy increased with cumulative dose of oxaliplatin and persistent neuropathy in a past cycle. Concomitant bevacizumab was not a risk factor when administered in stage IV disease but was associated with persistent neuropathy when administered experimentally in stage III. Females had no increased risk of either form of neuropathy. After 3 cycles, weight, body surface area, and prior acute neuropathy predicted time to persistent neuropathy. CONCLUSIONS: Routinely available clinical factors predict acute and persistent neuropathy associated with oxaliplatin. When validated, the proposed prognostic score for persistent neuropathy can help clinicians counsel patients about chemotherapy.

Brain imaging findings in symptomatic patients after allogeneic haematopoietic stem cell transplantation: correlation with clinical outcome.

OBJECTIVE: To investigate the risk factors for, and the incidence of, structural abnormalities on brain imaging in allogeneic haematopoietic stem cell transplant (HSCT) patients, and correlate these findings with survival. METHODS: We retrospectively reviewed all brain computed tomography (CT) and/or magnetic resonance imaging (MRI) studies obtained during the first post-HSCT year from 2004 thru 2007 in allogeneic HSCT recipients. RESULTS: A total of 128 patients had brain imaging in the first post-HSCT year. Forty one of these 128 patients (32 %) had structural abnormalities on brain imaging: cerebrovascular complications (n = 10), central nervous system (CNS) infection (n = 9), subdural fluid collection (n = 6), CNS recurrence of haematological malignancy (n = 11), and drug toxicity abnormalities (n = 5). The only significant risk factor for structural imaging abnormality was younger patient age (P = 0.01). MRI was significantly more likely than CT to provide specific imaging diagnosis of cerebral lesions (P = 0.001). HSCT patients with cerebrovascular complications have poor survival (P < 0.05). However, overall survival was not significantly worse for the 41 patients with the structural imaging abnormalities as compared to the 87 patients who had brain imaging but no structural abnormalities. CONCLUSIONS: There was no survival difference in patients whose brain imaging was normal or abnormal. However, there was poor outcome in patients with cerebrovascular complications after HSCT. KEY POINTS : • Brain imaging frequently demonstrates neurological complications following haematopoietic stem cell transplantation. • Younger HSCT patients are more likely to exhibit abnormal brain imaging findings. • HSCT recipients with cerebrovascular complications have the worst survival. • However brain imaging results are weak indicators of overall survival after HSCT.

The immune response to herpes simplex virus type 1 infection in susceptible mice is a major cause of central nervous system pathology resulting in fatal encephalitis.

This study was undertaken to investigate possible immune mechanisms in fatal herpes simplex virus type 1 (HSV-1) encephalitis (HSE) after HSV-1 corneal inoculation. Susceptible 129S6 (129) but not resistant C57BL/6 (B6) mice developed intense focal inflammatory brain stem lesions of primarily F4/80(+) macrophages and Gr-1(+) neutrophils detectable by magnetic resonance imaging as early as day 6 postinfection (p.i.). Depletion of macrophages and neutrophils significantly enhanced the survival of infected 129 mice. Immunodeficient B6 (IL-7R(-/-) Kit(w41/w41)) mice lacking adaptive cells (B6-E mice) and transplanted with 129 bone marrow showed significantly accelerated fatal HSE compared to B6-E mice transplanted with B6 marrow or control nontransplanted B6-E mice. In contrast, there was no difference in ocular viral shedding in B6-E mice transplanted with 129 or B6 bone marrow. Acyclovir treatment of 129 mice beginning on day 4 p.i. (24 h after HSV-1 first reaches the brain stem) reduced nervous system viral titers to undetectable levels but did not alter brain stem inflammation or mortality. We conclude that fatal HSE in 129 mice results from widespread damage in the brain stem caused by destructive inflammatory responses initiated early in infection by massive infiltration of innate cells.

Effects of CXCR3 signaling on development of fatal encephalitis and corneal and periocular skin disease in HSV-infected mice are mouse-strain dependent.

PURPOSE: The host inflammatory response to ocular infection with herpes simplex virus (HSV) can be either protective, with disease-free survival, or it can promote diseases such as HSV corneal disease (or herpes stromal keratitis [HSK] in humans) and encephalitis (HSE), depending on mouse strain. The role of CXCR3 chemokine signaling in HSV-induced central nervous system (CNS) inflammation and corneal disease was evaluated, and responses in genetically susceptible and resistant strains of mice were contrasted. METHODS: Resistant C57BL/6J (B6) and susceptible 129S6 (129) mice were given monoclonal antibodies (mAbs) to neutralize the CXCR3 ligands monokine induced by interferon-gamma (MIG, CXCL9) and interferon inducible protein-10 (IP-10, CXCL10) during HSV infection. In addition, the development of HSV disease was monitored in CXCR3-null mutant mice derived from resistant (B6) and susceptible (BALB/c) strains. Inflammatory cells infiltrating the cornea and brain stem were isolated and stained for flow cytometric analysis. RESULTS: MIG and IP-10 were induced in nervous system tissue after HSV inoculation by the corneal route. HSV-infected 129 mice treated with MIG- or IP-10-neutralizing mAbs showed significantly enhanced survival compared with mice treated with control isotype antibody, whereas survival of the B6 mice was unaltered. Similarly, greater survival was observed for BALB.CXCR3(-/-) mice compared with control BALB/c mice. Reduced CNS inflammation was documented that extended to the cornea, such that HSV corneal disease severity was reduced in susceptible BALB.CXCR3(-/-). In contrast, although survival of B6 and B6.CXCR3(-/-) mice was indistinguishable, B6.CXCR3(-/-) mice developed more severe corneal and periocular skin disease. CONCLUSIONS: The effects of CXCR3 signaling in HSV infection are strongly dependent on mouse strain.

Autologous haematopoietic stem cell transplantation fails to stop demyelination and neurodegeneration in multiple sclerosis.

The present study analyses autopsy material from five multiple sclerosis patients who received autologous stem cell transplantation. A total of 53 white matter lesions were investigated using routine and immunohistochemical stainings to characterize the demyelinating activity, inflammatory infiltrates, acutely damaged axons and macrophages/microglial cells. We found evidence for ongoing active demyelination in all of the five patients. The inflammatory infiltrate within the lesions showed only very few T cells and CD8+ cytotoxic T cells dominated the T cell population. B cells and plasma cells were completely absent from the lesions. High numbers of acutely damaged axons were found in active lesion areas. Tissue injury was associated with activated macrophages/microglial cells. The present results indicate that ongoing demyelination and axonal degeneration exist despite pronounced immunosuppression. Our data parallel results from some of the clinical phase I/II studies showing continued clinical disease progression in multiple sclerosis patients with high expanded disability system scores despite autologous stem cell transplantation.

The effect of height on paclitaxel nerve damage.

Dying-back neuropathies result in sensory loss and motor signs in the distal distribution of the longest nerves of the body. It would be expected, therefore, that taller individuals with dying-back neuropathies would tend to have worse nerve damage than shorter individuals. This hypothesis was tested in patients receiving high dose paclitaxel. Nerve conductions and quantitative sensory tests were obtained in 21 breast cancer subjects, prior to and 20-40 days after 725 mg/m(2) paclitaxel administered intravenously over 24 h. Despite the uniform dose of paclitaxel, there was a wide variation in post minus pre-paclitaxel changes. Analysis by linear regression showed that decrease of peroneal nerve compound muscle action potential amplitude was significantly greater in taller subjects (P=0.004), and increase in cold detection threshold was greater in taller subjects (P=0.02). No correlation with height was found for paclitaxel drug clearance, maximum concentration, and area under the curve. Decrease in sural sensory nerve action potential amplitude and increase in vibration detection threshold did not correlate with height. In summary, the wide variation of changes seen in neurophysiological tests suggests that multiple factors are involved in determining the severity of neuropathy. Nerve length is probably one of these factors. To determine whether the effect of height is clinically important would require additional study with a larger number of subjects and longer clinical follow-up.

Neurophysiological study of peripheral neuropathy after high-dose Paclitaxel: lack of neuroprotective effect of amifostine.

PURPOSE: To determine if there is a beneficial effect of amifostine in preventing or reducing the neuropathy induced by high-dose paclitaxel. METHODS: Breast cancer patients receiving high-dose infusional paclitaxel (725 mg/m(2)/24 h) in combination with doxorubicin (165 mg/m(2)/96 h) and cyclophosphamide (100 mg/kg/2 h; ACT) were studied on two autologous peripheral blood stem cell transplant protocols, one with and one without amifostine (740 mg/m(2) administered over 10 min before and 12 h after initiation of the paclitaxel infusion). Patients were evaluated before ACT and 20-40 days later with neurological examination, a composite peripheral neuropathy score, peroneal and sural nerve conduction studies, and quantitative sensory testing. RESULTS: There was no significant difference in paclitaxel maximum concentration, systemic clearance, or area under the curve determinations. Narcotic requirement as well as recovery of hematopoietic counts were also similar in subjects with or without amifostine. After ACT was administered, there was a decrease in peroneal nerve compound muscle action potential amplitude and sural nerve sensory action potential amplitude, as well as an increase in vibratory and cold detection thresholds. Clinical composite peripheral neuropathy scores were similar despite amifostine treatment; and logarithm to the base 2 ratios post/pre ACT showed no significant effect of amifostine on peroneal nerve compound muscle action potential, sural nerve sensory action potential, vibratory detection thresholds, or cold detection thresholds. All subjects had acroparesthesias and lost their ankle deep-tendon reflexes after administration of ACT. CONCLUSIONS: Single high-dose paclitaxel produces predictable clinical and neurophysiological changes so that patients receiving high-dose therapy are ideal subjects to test the effectiveness of neuroprotective agents. Amifostine was ineffective in preventing or reducing the neurotoxicity of high-dose paclitaxel.

A locus on mouse chromosome 6 that determines resistance to herpes simplex virus also influences reactivation, while an unlinked locus augments resistance of female mice.

During studies to determine a role for tumor necrosis factor (TNF) in herpes simplex virus type 1 (HSV-1) infection using TNF receptor null mutant mice, we discovered a genetic locus, closely linked to the TNF p55 receptor (Tnfrsf1a) gene on mouse chromosome 6 (c6), that determines resistance or susceptibility to HSV-1. We named this locus the herpes resistance locus, Hrl, and showed that it also mediates resistance to HSV-2. Hrl has at least two alleles, Hrl(r), expressed by resistant strains like C57BL/6 (B6), and Hrl(s), expressed by susceptible strains like 129S6 (129) and BALB/c. Although Hrl is inherited as an autosomal dominant gene, resistance to HSV-1 is strongly sex biased such that female mice are significantly more resistant than male mice. Analysis of backcrosses between resistant B6 and susceptible 129 mice revealed that a second locus, tentatively named the sex modifier locus, Sml, functions to augment resistance of female mice. Besides determining resistance, Hrl is one of several genes involved in the control of HSV-1 replication in the eye and ganglion. Remarkably, Hrl also affects reactivation of HSV-1, possibly by interaction with some unknown gene(s). We showed that Hrl is distinct from Cmv1, the gene that determines resistance to murine cytomegalovirus, which is encoded in the major NK cell complex just distal of p55 on c6. Hrl has been mapped to a roughly 5-centimorgan interval on c6, and current efforts are focused on obtaining a high-resolution map for Hrl.

High-dose immunosuppressive therapy and autologous peripheral blood stem cell transplantation for severe multiple sclerosis.

There were 26 patients enrolled in a pilot study of high-dose immunosuppressive therapy (HDIT) for severe multiple sclerosis (MS). Median baseline expanded disability status scale (EDSS) was 7.0 (range, 5.0-8.0). HDIT consisted of total body irradiation, cyclophosphamide, and antithymocyte globulin (ATG) and was followed by transplantation of autologous, granulocyte colony-stimulating factor (G-CSF)-mobilized CD34-selected stem cells. Regimen-related toxicities were mild. Because of bladder dysfunction, there were 8 infectious events of the lower urinary tract. One patient died from Epstein-Barr virus (EBV)-related posttransplantation lymphoproliferative disorder (PTLD) associated with a change from horse-derived to rabbit-derived ATG in the HDIT regimen. An engraftment syndrome characterized by noninfectious fever with or without rash developed in 13 of the first 18 patients and was associated in some cases with transient worsening of neurologic symptoms. There were 2 significant adverse neurologic events that occurred, including a flare of MS during mobilization and an episode of irreversible neurologic deterioration after HDIT associated with fever. With a median follow-up of 24 (range, 3-36) months, the Kaplan-Meier estimate of progression (>/= 1.0 point EDSS) at 3 years was 27%. Of 12 patients who had oligoclonal bands in the cerebrospinal fluid at baseline, 9 had persistence after HDIT. After HDIT, 4 patients developed new enhancing lesions on magnetic resonance imaging of the brain. The estimate of survival at 3 years was 91%. Important clinical issues in the use of HDIT and stem cell transplantation for MS were identified; however, modifications of the initial approaches appear to reduce treatment risks. This was a heterogeneous high-risk group, and a phase 3 study is planned to fully assess efficacy.

Intradermal doxorubicin reduces ganglionic reactivation of latent herpes simplex virus in mice after pretreatment with hypertonic saline.

Recurrent lesions from herpes simplex virus (HSV) occur after reactivation of latent HSV in neurons of sensory ganglion, axonal transport of reactivated virus, and HSV replication on the skin. A potential treatment strategy is to inject epithelial sites of frequent recurrences with anti-viral or cytotoxic agents that are taken up by nerve terminals and transported by axoplasmic flow to latently infected ganglionic neurons. Doxorubicin is transported by nerves and destroys the corresponding nerve cell bodies, but earlier attempts in HSV animal models required intraneural injection to eliminate HSV infection and this treatment destroyed the nerve and large portions of the ganglion. The present study used intradermal doxorubicin in latently infected mice that had been inoculated with HSV by the lip route and passively immunized at the time of inoculation. As found previously, doxorubicin injection in the lip 2 or more months after HSV inoculation did not eliminate HSV latency as evaluated by recovery of virus from trigeminal ganglionic explants. However, when hypertonic saline was injected in the same site 24 hr prior to doxorubicin, there was a 55% reduction of positive ganglionic explant cultures. Edema from the hypertonic saline may increase access of doxorubicin to nerve terminals. This technique with hypertonic saline, which has also been used to enhance virulence of HSV skin innoculation, may have general application of increasing axoplasmic transport of drugs or biologicals. Skin toxicity may preclude doxorubicin use for HSV recurrences in patients; however, the results of this study support the concept of anti-HSV treatment via retrograde axoplasmic transport.

High-dose immunosuppression and hematopoietic stem cell transplantation in autoimmune disease: clinical review.

Since 1996, a number of investigators have carried out phase I-II studies of high-dose immunosuppression with autologous hematopoietic stem cell transplantation (HSCT) in autoimmune diseases. Most of this activity has been in studies of multiple sclerosis (MS), systemic sclerosis (SSc), systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and juvenile idiopathic arthritis (JIA). Supported by animal models of antigen-induced autoimmunity, the rationale of HSCT is to time-shift the clinical autoimmunity to an earlier period, restoring self-tolerance. Even with the considerable experience of more than 200 transplantations since 1996, it is difficult to judge the optimal approach. This difficulty is in part because of the multiplicity of centers and protocols and the variability in patient eligibility and assessment, the extent of T-cell depletion, and the intensity of the preparatory regimens used. Other than that found in RA, treatment-related mortality has been higher than expected: 17% in SSc (with an additional 10% mortality from progressive disease), 13% in SLE, 13% in JIA, and 8% in MS. Protocol changes to improve safety have been instituted. These changes include the avoidance of high-dose rabbit antithymocyte serum in patients who received T-cell-depleted grafts, use of corticosteroids with granulocyte colony-stimulating factor during stem cell mobilization and as prophylaxis for the engraftment syndrome in MS, lung radiation shielding in SSc, and multiple precautions against the macrophage activation syndrome in JIA. Responses to primary and secondary endpoints have been seen, and there is a consensus among investigators and regulatory bodies that the time has come for randomized phase II-III studies. Each disease presents distinct difficulties: in MS, restriction of eligibility to patients with active inflammatory disease; in SSc, formulation of cardiopulmonary eligibility criteria to decrease risk; in SLE, judgment of whether HSCT adds any advantage to high-dose nonmyeloablative immunosuppressive treatment alone; and in RA, enhancement of response durability. All prospective randomized studies in these diseases must address problems in selection of the comparison nontransplantation treatment and appropriate stopping rules, particularly with treatment arms of unequal risk. Parallel trials in Europe and in the United States are in the late stages of design.