Lentiviral Gene Therapy Combined with Low-Dose Busulfan in Infants with SCID-X1

BACKGROUND

Allogeneic hematopoietic stem-cell transplantation for X-linked severe combined immunodeficiency (SCID-X1) often fails to reconstitute immunity associated with T cells, B cells, and natural killer (NK) cells when matched sibling donors are unavailable unless high-dose chemotherapy is given. In previous studies, autologous gene therapy with γ-retroviral vectors failed to reconstitute B-cell and NK-cell immunity and was complicated by vector-related leukemia.

METHODS

We performed a dual-center, phase 1-2 safety and efficacy study of a lentiviral vector to transfer IL2RG complementary DNA to bone marrow stem cells after low-exposure, targeted busulfan conditioning in eight infants with newly diagnosed SCID-X1.

RESULTS

Eight infants with SCID-X1 were followed for a median of 16.4 months. Bone marrow harvest, busulfan conditioning, and cell infusion had no unexpected side effects. In seven infants, the numbers of CD3+, CD4+, and naive CD4+ T cells and NK cells normalized by 3 to 4 months after infusion and were accompanied by vector marking in T cells, B cells, NK cells, myeloid cells, and bone marrow progenitors. The eighth infant had an insufficient T-cell count initially, but T cells developed in this infant after a boost of gene-corrected cells without busulfan conditioning. Previous infections cleared in all infants, and all continued to grow normally. IgM levels normalized in seven of the eight infants, of whom four discontinued intravenous immune globulin supplementation; three of these four infants had a response to vaccines. Vector insertion-site analysis was performed in seven infants and showed polyclonal patterns without clonal dominance in all seven.

CONCLUSIONS

Lentiviral vector gene therapy combined with low-exposure, targeted busulfan conditioning in infants with newly diagnosed SCID-X1 had low-grade acute toxic effects and resulted in multilineage engraftment of transduced cells, reconstitution of functional T cells and B cells, and normalization of NK-cell counts during a median follow-up of 16 months. (Funded by the American Lebanese Syrian Associated Charities and others; LVXSCID-ND ClinicalTrials.gov number, NCT01512888.).

Effect of stable xenon inhalation on internal carotid artery blood flow in unanesthetized monkeys

Stable xenon (Xe) gas, at inspired concentrations above 30%, reportedly increased cerebral blood flow (CBF) in animals and humans. An unpredictable Xe-induced elevation of CBF could result in erroneous CBF values being measured by Xe-enhanced computed tomography (Xe-CT). In order to detect a potentially rapid and transient effect of Xe on CBF, estimations of supratentorial CBF were obtained by Doppler flow probes chronically and bilaterally implanted on the internal carotid arteries of five adult monkeys. The unanesthetized monkeys with a clear plastic helmet were equilibrated for 15 min on a control gas (33% N2/67% O2) randomly exposed for 5 min to gas mixtures of either 33% Xe/67% O2 or 10% CO2/23% N2/67% O2. The mean control bilateral internal carotid artery blood flow (ICABF) was 23 +/- 10 ml/min (mean +/- SD), mean arterial pressure (MAP) was 101 +/- 13 mm Hg, and PaCO2 was 34 +/- 6 mm Hg. Inhalation of 33% Xe in O2 did not change the ICABF, MAP, or PaCO2. Inhalation of 10% CO2 in O2 increased the ICABF to 39 +/- 15 ml/min (p <0.001), MAP to 112 +/- 16 mm Hg (p <0.05), and PaCO2 to 54 +/- 5 mm Hg (p <0.001). The lack of change in ICABF and PaCO2 with 32% Xe inhalation suggests that a clinically relevant change in CBF is unlikely.

Physiologic implications of adding small amounts of carbon dioxide to the gas mixture during inhalation of xenon

In addition to being a physiologically active tracer of CBF, xenon (Xe) in subanesthetic concentrations produces a relatively mild lowering of carbon dioxide (CO2) in the blood and elevation of transcranial Doppler (TCD) velocity. The addition of small concentrations of CO2 (0.4-1.2%) to the inhaled mixture produced no measurable effect on end tidal (P(et)) CO2 or TCD velocity. Cerebral blood flow (CBF) alterations induced by Xe are minimized by allowing P(et)CO2 to fall, permitting quantitative measurement of CBF by the Xe/CT CBF method.

Effects of H-7 are not exclusively mediated through protein kinase C or the cyclic nucleotide-dependent kinases

Culturing murine T cell tumor lines in the presence of the protein kinase inhibitor H-7 for 4 days led to their dependence on H-7 for maximal constitutive proliferation. Withdrawal of H-7 from H-7-conditioned cells led to inhibition of proliferation and cell death. The mechanism underlying this H-7 dependence does not appear to be related to clonal selection or to effects on protein kinase C or the cyclic nucleotide-dependent kinases. This suggests that all the effects of the widely used H-7 may not be completely understood, and that H-7 may be useful in the dissection of the complex patterns of growth regulation in T cell malignancies.

T cell receptor beta chain gene rearrangement shared by murine T cell lines derived from a site of autoimmune inflammation

Advances in our understanding of the structure and molecular biology of the T lymphocyte antigen-receptor have now made it feasible to study human autoimmune diseases using new approaches. One such approach involves cloning of T cells from sites of autoimmune pathology followed by identification of putative disease-related T cell oligoclonality at the level of the T cell receptor gene rearrangements. We have now tested the feasibility of this approach in an animal model of autoimmunity, murine experimental allergic encephalomyelitis (EAE). Spinal cord-derived, self (murine) myelin basic protein (MBP)-reactive T cell lines and sublines were analyzed at the level of their receptor beta chain rearrangements using Southern blots. We now report that the MBP-reactive T cell lines and sublines derived from the spinal cords of four of five SJL/J mice with EAE share a 14.5-kb rearranged T cell receptor beta 1 band on Southern blots. A spinal cord-derived T cell line that was reactive to purified protein derivative of tuberculin (PPD), several lymph node-derived ovalbumin- and PPD-reactive T cell lines, as well as one MBP-reactive spinal cord-derived T cell line did not share this 14.5-kb rearranged beta 1 band. These results suggest that analysis of the antigen receptors used by T cells cloned from sites of inflammation may be a useful initial approach for identifying pathogenetically relevant T cells in the study of certain human autoimmune diseases.

The protein kinase C inhibitor H-7, inhibits antigen and IL-2-induced proliferation of murine T cell lines

Activation of protein kinase C has been shown to be involved in the activation pathway of many cell types. Recently, a number of investigations have suggested that protein kinase C plays an essential role in T lymphocyte activation. The recent synthesis of the protein kinase inhibitors, H-7 and HA1004, have now made possible a new approach for testing the relevance of protein kinase C in T cell activation and proliferation. We now report that the antigen-induced and interleukin-2-induced proliferation of murine T cell lines can be consistently inhibited by the protein kinase C inhibitor, H-7. HA1004, a somewhat more potent inhibitor of cyclic nucleotide-dependent protein kinases, but a significantly weaker inhibitor of protein kinase C than H-7, demonstrated no consistent inhibition of these T cell responses. These results represent a further demonstration that protein kinase C plays an essential role in the activation of T cells.

Statistical analysis of statural growth following kidney transplantation

Factors affecting the growth rates of 59 children and adolescents for the first 2 years following kidney transplantation were evaluated. The factors assessed were age at transplantation, renal function, prednisone dosage, donor source, and prior history of transplantation. The observed growth velocity was expressed as the percentage, of the growth velocity predicted by bone age. Normal growth (greater than or equal to 80%) was exhibited by 37% of the patients and 22% had accelerated growth (greater than or equal to 100%). The chronologic age at transplantation did not correlate significantly with growth when bone age was used as the reference for expected velocity. Males grew better than did females. There was a unique sex/race interaction with black males growing most rapidly. Better renal function, the ability to lower prednisone dosage, alternate day prednisone administration, and a decreasing diastolic blood pressure were positively correlated with better growth rates after transplantation. The donor source and prior history of transplantation did not significantly influence growth rate.

Statistical analysis of statural growth following kidney transplantation

Factors affecting the growth rates of 59 children and adolescents for the first 2 years following kidney transplantation were evaluated. The factors assessed were age at transplantation, renal function, prednisone dosage, donor source, and prior history of transplantation. The observed growth velocity was expressed as the percentage of the growth velocity predicted by bone age. Normal growth (greater than or equal to 80%) was exhibited by 37% of the patients and 22% had accelerated growth (greater than or equal to 100%). The chronological age at transplantation did not correlate significantly with growth when bone age was used as the reference for expected velocity. Males grew better than did females. There was a unique sex/race interaction with black males growing most rapidly. Better renal function, the ability to lower prednisone dosage, alternate day prednisone, and a decreasing diastolic blood pressure were positively correlated with better growth rates after transplantation. Donor source and prior history of transplantation did not significantly influence growth rate.

A remotely programmable insulin delivery system. Successful short-term implantation in man

A remotely controlled, programmable insulin delivery system was implanted in a diabetic man and the feasibility of the technique was examined. Specific problems included (1) development of an appropriate surgical approach, (2) identification of methods to assess the integrity of the insulin delivery system following implantation, and (3) assessment of plasma glucose and free-insulin profiles obtained with the implanted system. The insulin pump was implanted submuscularly through a midline abdominal incision. The insulin reservoir was placed subcutaneously to allow percutaneous refilling. The insulin delivery catheter terminated in the peritoneal space. No postoperative wound infection occurred and rapid healing of the surgical site ensued. In vivo assessment of the system included (1) dye contrast roentgenography, (2) vasopressin stimulation, and (3) reservoir volume monitoring. Short-acting insulin was then placed in the implanted reservoir and delivered by the system for one month. Mean plasma glucose concentration declined to normal levels, as did glycosylated hemoglobin. Plasma insulin profiles were normalized with appropriate insulin peaks with each meal. We conclude that implantation of a remotely programmable insulin pump is feasible in type I diabetic man. Additional studies are necessary to define which patients will benefit from this type of insulin delivery system.

Malignant external otitis. Cure with adjunctive hyperbaric oxygen therapy

Malignant otitis externa developed in a 55-year-old man with diabetes. This Pseudomonas aeruginosa infection was refractory to high-dose moxalactam disodium therapy, despite sufficient in vitro tube dilution sensitivity results. When adjunctive hyperbaric oxygen therapy was added to the treatment regimen, the infection resolved.

Perilymphatic fistulas

The oft-quoted dictum that clinical suspicion rather than any specific test leads to the diagnosis is confirmed by our study. Further work is needed to define the vestibular findings more precisely and to work out relationships between CSF and perilymph pressures. Temporal bone study will be necessary to document the double membrane break theory. Future study may include analysis of suspected fistula fluid to determine if it represents a mixture of perilymph and endolymph. From our study, fistulae may occur from minimal or no trauma. The presentation is usually subtle. Because no diagnostic test is available to assure correct diagnosis, one must maintain a high index of suspension. Diagnosis usually cannot be made until the ear is surgically explored. The low morbidity of an exploratory tympanotomy, coupled with the high positive to negative ratio of exploration and the high degree of successful results, leads the authors to encourage exploration. Indeed, the overall concensus is that many active fistulae remain undiagnosed because of the lack of suspension and the reluctance to explore an ear without a concrete preoperative diagnosis. The duration of the fistulae and the recurrent nature of the problem poses another diagnostic dilemma. The first positive exploratory tympanotomy for perilymphatic fistula often leaves the surgeon with a dichotomy of emotion from pride of a correct diagnosis to fear that perhaps his observations of the minute clear fluid seepage was an error. Reversal of patient symptoms quickly erases such fears and presumptive diagnosis of perilymphatic fistula becomes easier to make. Eventually, one begins to worry, "How many have I missed."

Future therapy of the insulin-dependent diabetic patient--the implantable insulin delivery system

An implantable insulin delivery system has several advantages not shared by currently available, portable external delivery devices. First, since the implantable system does not come in contact with the external environment, insulin delivery routes other than the subcutaneous tissue may be utilized without the danger of infection. These alternative routes may provide more rapid insulin absorption, enhanced hepatic insulinization, and improved diabetic control for “C”-peptide-negative brittle diabetic patients. Second, the implantable system is protected from external trauma, permitting a wider range of daily activities and sporting events. Third, the implantable system is easily concealed by clothing, thereby increasing patient acceptance of it. However, an implantable system also has disadvantages. First, surgery will be required to implant or explant the pump module and reservoir, and second, the implanted system must be highly reliable and include failsafe mechanisms to insure the safety of the recipient. These advantages and disadvantages have resulted in delineation of general specifications for an inv plantable insulin delivery system. Desirable features of an implantable insulin delivery system include (1) reliability and failsafe operation, (2) being implantable and explantable under local anesthesia, (3) long battery life, (4) multiple insulin delivery rates, (5) small size and weight, (6) biocompatible materials, (7) remote programmability based upon recipient blood glucose monitoring, and (8) ability to deliver concentrated insulin with infrequent reservoir refilling. Using available technology, each of these specifications has been incorporated into the functioning of our current implant system, which is being tested in diabetic dogs. Future experiments in man will undoubtedly alter and add to the current specifications.

Some engineering aspects of insulin delivery systems

The characteristics of electronically controlled insulin delivery systems are presented. Early experiments with an external system have shown promise in providing improved glycemic control over conventional methods of single or multiple subcutaneous insulin injections. The encouraging results with external insulin delivery systems have led to the development and early testing in dogs of an implantable system with remote controls to permit variable insulin flow rates. A number of questions remain to be answered before widespread experimentation with external and implanted insulin delivery systems is possible. There appears to be no major development problems with the engineering aspects of such systems.

Civilian air travel and the otolaryngologist

Thousands of individuals fly commercial airlines and private aircraft daily. One airline boasts of serving more than 100,000 passengers each day. Of these individuals exposed to barometric alterations, an undocumented number will develop significant barotrauma and may seek help from an otolaryngologist. Although many otolaryngologists learn the mechanics and management of barotrauma as military flight surgeons, residents in otolaryngology usually receive no specific training in this area. Because private and commercial aviation are so common today, we believe that a basic knowledge of barometric changes experienced while flying is essential for the practicing otolaryngologist. These basic principles are covered in this presentation. Case histories will also be discussed. One patient, who presented with signs of perilymph fistula, including sensorineural deafness and abnormal ENG, recovered spontaneously.

Basilar artery migraine presenting as fluctuating hearing loss and vertigo

A review of the literature on basilar artery migraine as well as a brief overview of classic migraine is given. Diagnosis and management are also discussed as well as six case histories.

Neoglottic reconstruction after total laryngectomy: a preliminary report

This paper is a preliminary report on neoglottic reconstruction of the larynx after total laryngectomy following the techniques described by Staffieri. Also included are general observations on the criteria for selecting candidates for this procedure. At the University of Texas Medical Branch in Galveston, this procedure has been attempted on eight candidates. Reconstruction was accomplished in six, of whom five achieved satisfactory speech, providing an 80% success rate. One of the five did not like the quality of his voice and refused to use it. The sixth produced speech with difficulty and is still undergoing speech therapy. One patient died from recurrence before a second stage could be carried out, and another patient did not have sufficient tissue for neoglottic reconstruction after total laryngectomy. Three patients developed salivary fistulas at the drain site, but all closed spontaneously with the application of pressure. From this data, one may conclude that this technique offers much potential and warrants further study.

The biphasic acoustic reflex: a new perspective

The anatomic, neurologic, and physiologic characteristics of the middle ear structures have created confusion concerning the nature of the intraaural muscle reflex. After reviewing the relevant literature, we correlated this information with our studies of human temporal bones and computer analyses of the acoustic reflex responses of individuals with normal hearing. Our hypothesis is that although the stapedius is the initiator of the reflex and the primary contributor to ossicular chain fixation, the tensor tympani is responsible for the major observed response. The negative deflection present in normals tested on the impedance bridge is caused by the stapedius, whereas the large positive deflection is the result of the tensor tympani contraction. We postulate that proprioceptive feedback mechanisms located within the stapedius muscle and tendon permit and/or initiate tensor tympani contraction during acoustic stimulation.

Injury to the facial nerve associated with the use of a disposable nerve stimulator

Clinical observations and experimental data from this study support the thesis that the disposable Weck nerve locator/stimulator may induce neural damage. This potential damage may cause at least a temporary paresis. Although more study is required to better document the method, degree, and factors influencing injury, we believe that enough evidence is present to induce caution and warrant further study. We recommend that the stimulators be used with caution on the lowest setting possible and with as little contact with the nerve as possible.

Otologic and otoneurologic injuries in divers: clinical studies on nine commercial and two sport divers

In the past two decades, we have seen a great increase in the number of injuries from commercial and sport diving. During this time, our knowledge of the physiology and pathophysiology of diving has also increased. As a result, we now can accurately diagnose and successfully treat many of these injuries. Of the commercial and sport divers examined as pateints in the Department of Otolaryngology at the University of Texas Medical Branch in Galveston, Tex., between September, 1974, and May, 1975, 11 showed positive otologic and otoneurologic findings which are reported herein. One patient was surgically explored for an oval window fistula. In localizing and classifying these injuries, we have utilized extensive and broad-based test batteries, which include complete history, otologic and otoneurologic physical examination, audiometry, a central auditory test battery, and a vestibular test battery. These tests are described. The findings in each of the divers are illustrated and analyzed. This article further describes the use of these test batteries, which were employed to localize otoneurologic pathology in this sample of injured divers. Based on these cases, we have expanded and modified Edmonds' classification of the etiology of vertigo related to diving. We feel that the test batteries which we describe, or similar tests, should be part of the otologic and otoneurologic workup of injuries divers.

Otoadmittance measurements in cases of dual ossicular disorders

Audiologic evaluations, including otoadmittance measurements, were obtained on two patients, each of whom had dual, series-connected disorders of ossicular fixation and disarticulation. In one case, the disarticulation was the lateral-most disorder; in the other case the fixation was the lateral-most disorder. In both cases, it was the lateral-most disorder that had the dominant effect on the otoadmittance of the tympanic membrane, due to the fact that the sites of the two disorders were connected in series with the tympanic membrane.