Development of gene therapies-lessons from nusinersen.

The nusinersen development and approval process provide important lessons regarding the pathway to marketing approval for gene therapies. These lessons emphasize rigorous clinical trial design, flexibility in trial design and analysis, a collaborative effort with regular communications between the drug developer and the Food and Drug Administration (FDA), and use of FDA's expedited programs. These lessons are critical to the development of gene therapies for the treatment of serious or life-threatening rare diseases.

Effect of carbenoxolone on the plasma renin activity and hypothalamic-pituitary-adrenal axis in congenital adrenal hyperplasia due to 21-hydroxylase deficiency.

OBJECTIVE: To test the hypothesis that carbenoxolone, an inhibitor of 11beta-hydroxysteroid dehydrogenase, might augment the ACTH-suppressing and mineralocorticoid activities of hydrocortisone without a corresponding increase in peripheral hydrocortisone effects, we assessed the effects of carbenoxolone in patients with congenital adrenal hyperplasia. DESIGN AND PATIENTS: Six patients with classic 21-hydroxylase deficiency (5 salt-losing, 1 nonsalt-losing) were enrolled in this study. The study protocol involved 3 treatment periods (except for patient 3): phase 1, hydrocortisone and fludrocortisone; phase 2, hydrocortisone, fludrocortisone and carbenoxolone; phase 3, hydrocortisone and carbenoxolone. Patient 3 was not treated with fludrocortisone at baseline, so she participated only in phase 1 (hydrocortisone only) and phase 2 (hydrocortisone and carbenoxolone). Hydrocortisone and fludrocortisone dosages were kept the same during the study except for the discontinuation of fludrocortisone during phase 3. MEASUREMENTS: Plasma adrenal androgens or their precursors (androstenedione, 17-hydroxyprogesterone, and testosterone, and urine pregnanetriol); plasma cortisol, cortisol-binding globulin, ACTH, apparent cortisol metabolic clearance, 24-h urine 17-hydroxysteroids, and urine free cortisol; mineralocorticoid activity, as measured by plasma renin activity, body weight, plasma potassium, and mean blood pressure; fasting insulin/glucose ratio, protein balance, % eosinophils in peripheral blood, and total urine pyridinoline and deoxypyridinoline; TRH stimulation of TSH and pyridostigmine/GHRH stimulation of growth hormone. RESULTS: Compared to phase 1, the addition of carbenoxolone (with or without concurrent fludrocortisone administration) produced statistically significant decreases of 20-50% in mean plasma 17-hydroxyprogesterone, androstenedione, and renin activity. Since carbenoxolone also decreased the apparent metabolic clearance rate of cortisol by 20%, other measures of systemic glucocorticoid activity were examined. Carbenoxolone did not produce a cushingoid appearance or increase body weight, blood pressure, blood glucose or plasma insulin levels. Carbenoxolone also did not suppress stimulated GH levels, but did decrease TRH-stimulated TSH levels by approximately 20% (P < 0.05). CONCLUSION: Carbenoxolone can augment the adrenal androgen-suppressing activity of hydrocortisone in patients with 21-hydroxylase deficiency. These observations support the hypothesis that selective inhibition of enzymes that metabolize cortisol may lead to new approaches to improve the treatment of congenital adrenal hyperplasia.

Physiological and molecular aspects of mineralocorticoid receptor action in pseudohypoaldosteronism: a responsiveness test and therapy.

Pseudohypoaldosteronism (PHA), characterized by congenital resistance to aldosterone and excessive salt loss, has been traditionally treated with salt replacement. Although the mineralocorticoid receptor (MR) has been suggested as a potential locus of the defect in this disease, no such abnormality has been identified as yet. We studied a 17-yr-old male patient with congenital multifocal target organ resistance to aldosterone. Both carbenoxolone, an 11 beta-hydroxysteroid dehydrogenase inhibitor, and a high dose of fludrocortisone normalized the patient's serum electrolyte concentrations and decreased his urinary excretion of sodium, suggesting that this patient's resistance was partial and could be overcome by high concentrations of endogenous or exogenous mineralocorticoids. We hypothesized that the beneficial effect of these treatments was mostly mediated by the MR, because the administration of dexamethasone, while this patient was receiving a therapeutic dose of carbenoxolone, caused its reversal. These findings convinced us that there was functional, albeit possibly defective, MR in this patient and led us to perform molecular studies. Both alleles of the MR gene were expressed in the patient and his clinically and biochemically normal father. A conservative heterozygous mutation (A760-->G760, Ileu180-->Val180) and a nonconservative homozygous mutation (C944-->T944, Ala241-->Val241) were identified in the complementary DNA of both the patient and his father. The first untranslated exon and 0.9 kilobase of the 5'-regulatory region were also identical in the two men. It appears that the mutations causing amino acid substitutions represent polymorphisms, as we found high frequencies of both in the general population. We conclude that carbenoxolone and fludrocortisone may help define the presence of functional MR in patients with PHA and that the former could be used in the long term therapy of this disease. We hypothesize that the defect causing PHA in this patient might be in a post-MR step of aldosterone action.

Low sodium intake enhances sensitivity of 11-deoxycortisol and deoxycorticosterone to ACTH in ACTH-suppressed normal subjects.

Continued administration of ACTH to patients with hypopituitarism produced normal increases in steroids dependent on microsomal cytochrome P450(21) and P450(17 alpha) but reduced responses of steroids dependent on mitochondrial cytochrome P450(11 beta-18). To explore possible mechanisms and to determine whether this dissociation occurs with short-term ACTH suppression, we have examined the steroid responses to ACTH after 1 h in 12 normal subjects after equilibration on sodium intakes of 124 mmol/d [normal sodium diet (NSD)], 22 mmol/d [low sodium diet (LSD)], and 240 mmol/d [high sodium diet (HSD)] before and during continued ACTH suppression with dexamethasone (DEX). Two distinct patterns of steroid responses were observed. Deoxycorticosterone (DOC) responses were initially reduced during LSD-DEX but eventually returned to the NSD-control (NSD-CONT) values; in contrast 18-hydroxydeoxycorticosterone and corticosterone remained suppressed. 11-Deoxycortisol and 21-deoxycortisol showed patterns similar to DOC, with a return to normal ACTH responses on LSD-DEX. Basal cortisol levels were reduced and the ACTH response was unchanged by LSD. HSD-DEX reduced basal levels of all steroids as well as their ACTH responses. LSD and/or increased activity of the renin-angiotensin system have a significant impact on 17 alpha- and 21-hydroxylation functions in the zona fasciculata to maintain a normal ACTH response of microsomally dependent steroids under these conditions. In contrast, on HSD-DEX with the renin-angiotensin system suppressed, there is generalized impairment of steroid responses to ACTH.

Tc-99m uptake in a parathyroid adenoma. Potential pitfall in Tc-99m/Tl-201 subtraction imaging.

The authors describe a patient with primary hyperparathyroidism who had a large mediastinal parathyroid adenoma that avidly concentrated both Tc-99m pertechnetate and Tl-201. This unusual finding is presented as another potential reason for false-negative findings in Tc-99m/Tl-201 subtraction scintigraphy in hyperparathyroidism.

Reassessment of the predictive value of the postural stimulation test in primary aldosteronism.

Postural stimulation tests (PST) from 146 patients with primary aldosteronism were reviewed: 83 had an aldosterone-producing adenoma (APA), 48 idiopathic hyperaldosteronism (IHA), nine primary adrenal hyperplasia (PAH), and six aldosterone-producing renin-responsive adenoma (AP-RA). Plasma aldosterone and cortisol levels were measured after overnight recumbency and in response to upright posture for 2 to 4 h. The test was considered invalid in 32% of the patients because cortisol levels increased during the maneuver. As both cortisol and aldosterone are responsive to ACTH in subjects with primary aldosteronism, as well as in normal subjects, we examined their percent variation instead of the absolute values. In order to validate those tests in which cortisol increased, we subtracted the percent cortisol change from the percent aldosterone response. An aldosterone increase of less than 30% (considered a positive response for the presence of an adenoma) identified 76 of the 89 patients with an adenoma (APA and AP-RA) (sensitivity of 85%). Among the 13 false-negative tests, six were proven cases of AP-RA. In each and every case an adenoma was detected by CT/MRI scanning (or bilateral adrenal vein catheterization). Hypertension was ameliorated or cured by surgery. A postural response of less than 30% was also present in 11 of the 57 patients who did not have a discrete adenoma confirmed by imaging techniques (specificity of 81%). Among these false-positive results there were the nine cases of PAH where the hypertension could be ameliorated or cured by partial removal of hyperplastic adrenal tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Continuous adrenocorticotropin administration in hypopituitarism produces asynchronous increases of deoxycorticosterone and 11-deoxycortisol relative to other reduced zona fasciculata steroids.

Short term suppression of ACTH by dexamethasone effects limited reduction in plasma deoxycorticosterone (DOC) while cortisol levels are almost completely suppressed in normal control subjects. The zona fasciculata (ZF) microsomal cytochrome P-450(21) appeared less influenced by lack of ACTH than mitochondrial cytochrome P-450(11 beta-18). Eleven patients with hypopituitarism were studied to quantitate basal ZF microsomal and mitochondrial derived steroids and their acute and extended responses to ACTH. Basal levels of 11-deoxycortisol (S) and DOC were modestly reduced (70% and 53%, respectively), while other ZF steroids were almost completely absent. Acute and prolonged ACTH treatment amplified the discrepancy in both plasma levels and production rates. DOC and S demonstrated prompt and sustained increases similar to those in normal controls, while cortisol, 18-hydroxydeoxycorticosterone, and corticosterone showed a slow subnormal recovery of steroid production. The preservation of microsomal cytochrome P-450(21) and P-450(17 alpha) to maintain DOC and S levels contrasts the reduced and delayed responses of steroids dependent on mitochondrial cytochrome P-450(11 beta-18), cortisol, corticosterone, and 18-hydroxydeoxycorticosterone. A greater effect of ACTH deficiency on mitochondrial over microsomal cytochrome P-450 activity is demonstrated, and in addition, the possibility is raised that other non-ACTH regulators sustain microsomal cytochrome P-450(21) and P-450(17 alpha) in a setting of reduced ACTH-stimulated factors.

Correctable subsets of primary aldosteronism. Primary adrenal hyperplasia and renin responsive adenoma.

Among 154 cases of primary aldosteronism seen in the General Clinical Research Center at San Francisco General Hospital, twelve patients did not fulfill established characteristics of an aldosterone producing adenoma (APA) or idiopathic hyperaldosteronism (IHA). Eight patients had nodular adrenocortical hyperplasia; plasma and urinary aldosterone were elevated and responses to stimulatory and suppressive maneuvers demonstrated the same autonomy seen in patients with APA. This subset is designated primary adrenal hyperplasia. Four additional patients also had elevated aldosterone levels that were responsive to these maneuvers, similar to IHA, but had unilateral tumors. This group has been designated as aldosterone-producing renin-responsive adenoma. Eleven patients had unilateral adrenalectomy and one preferred prolonged spironolactone therapy, resulting in a sustained cure or amelioration of hypertension, hypokalemia and normalization of aldosterone production.

Stimulation and suppression of the mineralocorticoid hormones in normal subjects and adrenocortical disorders.

In summary, maneuvers that affect the RAS stimulate or suppress solely aldosterone and 18-OHB and have little, if any, effect on DOC, 18-OHDOC, B, or cortisol. The magnitude of aldosterone response seems to be of equal magnitude for all stimulatory or suppressive maneuvers as used in the present protocols. Although primarily originating in the ZG, some secretion of 18-OHB from the ZF is evident by its disproportionate responses (in relation to aldosterone) to maneuvers challenging ACTH. The prompt and marked increases the 18-OHDOC and B after ACTH make them the most sensitive "markers" of the ZF steroid activity. The application of those maneuvers and MCH measurements to adrenal disorders should help to further characterize their pathophysiology.

Identification and implications of new types of mineralocorticoid hypertension.

200 patients with mineralocorticoid hypertension were studied at the Clinical Study Center. The study of 150 patients with primary aldosteronism revealed five distinct subsets based on their responses to the upright posture, after administration of intravenous saline, deoxycorticosterone acetate, and spironolactone. Two new types were identified--aldosterone producing responsive adenoma (AP-RA) and primary adrenal hyperplasia (PAH). Patients with AP-RA maintained normal physiologic responses to the above maneuvers. Patients with PAH had responses similar to patients with an aldosterone producing adenoma (APA) but no tumor was identified. Both types were cured by unilateral adrenalectomy. There has been no change in subtype in up to 20 years of follow-up. The notion of a continuum from low renin hypertension to APA is not supported. Primary deoxycorticosteronism caused by a benign adrenal adenoma, malignancy and hyperplasia is described. Uniquely, overproduction of the 17-deoxysteroids of the zona fasciculata occurs with normal 17-hydroxy function. After the removal of a benign adenoma the contralateral adrenal gland revealed a delay in the 17-deoxysteroid responses to ACTH in the face of normal cortisol increases. This suggests that an independent pituitary regulator of the 17-deoxypathway may exist. Other hypertensive disorders with excessive deoxycorticosterone production are linked with increases of ACTH and cortisol levels. The hallmarks of primary deoxycorticosteronism are hypertension with hypokalemia, suppression of renin and aldosterone, and overproduction of the 17-deoxysteroids.

The regulation of the 17-deoxy steroids in man.

One must consider the 17-DOS as a biosynthetic pathway with multiple regulatory factors. ACTH is its dominant regulator but in the absence of ACTH and in conditions where plasma renin activity is increased, this biosynthetic pathway maintains its sensitivity to exogenous ACTH. Suppression of the renin system delays the general recovery of aldosterone after the removal of an aldosterone producing adenoma but not of the 17-DOS: a pattern also showed after the removal of a DOC-producing adenoma. In addition to the possible role of the renin system there remain inexplicable situations in its regulation that cannot be explained by ACTH and renin. Our studies suggest that a non-renin, non-ACTH factor may influence the basal production of these steroids, and by its reduction, permits deviation of steroid substrate to cortisol production. This sequence may be operative in the "stress syndrome". Finally, one of the more interesting phenomenonologic patients who has been observed is a young male who has the biochemical findings and clinical signs of DOC excess with hypertension, hyperplasia, suppression of aldosterone and the RAS, and normal cortisol levels. All the 17-DOS are elevated and both adrenal veins have high concentrations. He represents excessive stimulation of this pathway by putative 17-deoxy regulator excess. The renin system is suppressed and ACTH levels are normal. Treatment with suppressive doses of glucocorticoid hormones diminishes the elevated 17-DOS and cortisol and ameliorates blood pressure. In summary, there seems to occur in clinical disorders and contrived experimental settings, suggestions that a non-renin, non-ACTH factor can regulate the 17-DOS, absence can explain some of the unusual conditions described (Fig. 1). The 17-DOS, while a vestigial pathway, may still cause disease, and provide clues to central organization of the adreno-cortical response to injury, stress, and disease.

Pathophysiology of deoxycorticosterone-secreting adrenal tumors.

Two patients with hypermineralocorticoidism due to deoxycorticosterone (DOC) excess are described. The plasma 17-deoxysteroids of the zona fasciculata (ZF), namely DOC, corticosterone, 18-hydroxydeoxycorticosterone, and 18-hydroxycorticosterone, were elevated. Plasma androgen concentrations were normal, and plasma aldosterone and renin levels were low. One patient, who had benign adrenocortical adenoma, had normal plasma cortisol levels. The other patient, who had metastatic adrenocortical carcinoma, had low plasma cortisol, presumably due to elevated plasma corticosterone levels. While tumors producing only 17-deoxysteroids are rare, they have provided new insights into the regulation of 17-deoxysteroid secretion by the ZF. Presumptive suppression of a non-ACTH factor by adenoma-produced DOC transiently impaired the early postoperative responses to ACTH of the ZF 17-deoxysteroids of the contralateral adrenal. The dissociation of 17-deoxysteroids from cortisol in normal subjects given either dexamethasone or DOC acetate provides additional evidence for such a factor.

Adrenocortical function in acquired immunodeficiency syndrome.

Clinical features of adrenal steroid deficiency occur in patients with the acquired immunodeficiency syndrome (AIDS). To determine the frequency of aberrations in peripheral steroid levels in patients with AIDS and AIDS-related complex (ARC) we measured morning recumbent plasma cortisol, deoxycorticosterone, 18-hydroxydeoxycorticosterone (18-OHDOC), corticosterone, aldosterone, and 18-hydroxycorticosterone concentrations before and after administration of 0.25 mg ACTH (Cosyntropin) in 74 randomly selected hospitalized patients with AIDS and 19 patients with ARC. Basal (0800 h) cortisol levels in the AIDS patients were significantly higher (P less than 0.01) than those in normal subjects, while other ACTH-dependent steroids of the 17-deoxypathway, deoxycorticosterone, corticosterone, and 18-OHDOC, were normal. These latter steroids increased subnormally in response to ACTH in patients with either AIDS (P less than 0.001) or ARC (P less than 0.005), but in ARC patients plasma 18-OHDOC levels were significantly higher than in those with AIDS (P less than 0.001). Supraphysiological doses of ACTH were then administered for 3 consecutive days to 14 patients with AIDS and 9 with ARC, which confirmed and amplified the subnormal responses of these steroids in AIDS. The mean plasma cortisol response was reduced on the third day only in AIDS patients, whereas in the ARC patients the steroid responses were normal. Angiotensin III infusion and postural stimulation increased plasma aldosterone and 18-hydroxycorticosterone levels in AIDS and ARC patients. Defective stimulation of 18-OHDOC alone or in combination with defective stimulation of other 17-deoxysteroids can be a harbinger of subsequent impaired adrenal capacity in AIDS.