Real-world evidence to support regulatory decision-making for medicines: Considerations for external control arms

Randomized clinical trials (RCTs) are the gold standard in producing clinical evidence of efficacy and safety of medical interventions. More recently, a new paradigm is emerging-specifically within the context of preauthorization regulatory decision-making-for some novel uses of real-world evidence (RWE) from a variety of real-world data (RWD) sources to answer certain clinical questions. Traditionally reserved for rare diseases and other special circumstances, external controls (eg, historical controls) are recognized as a possible type of control arm for single-arm trials. However, creating and analyzing an external control arm using RWD can be challenging since design and analytics may not fully control for all systematic differences (biases). Nonetheless, certain biases can be attenuated using appropriate design and analytical approaches. The main objective of this paper is to improve the scientific rigor in the generation of external control arms using RWD. Here we (a) discuss the rationale and regulatory circumstances appropriate for external control arms, (b) define different types of external control arms, and (c) describe study design elements and approaches to mitigate certain biases in external control arms. This manuscript received endorsement from the International Society for Pharmacoepidemiology (ISPE).

T cell-specific expression of the murine CD3delta promoter

T cell-specific expression of human and mouse CD3delta is known to be governed by an enhancer element immediately downstream from the gene. Here we demonstrate by transgenic and in vitro studies that the murine CD3delta (mCD3delta) promoter prefers to be expressed in cells of the T lineage. Deletion analyses of a promoter segment (-401/+48 bp) followed by transient transfections indicate that upstream elements between -149 and -112 bp contribute to full expression of the gene. Furthermore, a core promoter region -37/+29 appears to contribute to a T cell specificity. Using substitution mutant scanning, four positive and one negative regulatory elements were found within the mCD3delta core promoter. The first two positive elements comprise two classical initiator-like sites, which recruit TFII-I, whereas a third contains a functional Ets binding site. Immediately adjacent to the observed transcription start site is a negative element that utilizes the transcription regulator YY1. The last positive regulatory element contains a potentially functional CREB binding site and the minor transcriptional start site. Because NERF-2, Elf-1, and Ets-1 are expressed preferentially in lymphocytes and because, in addition, YY1 represses the promoter activity strongly in non-T cells, we conclude that the combination of these transcription factors contributes to the T cell-specific expression pattern of mouse CD3delta.

Exposure of the anterior spine: technique and experience with 66 patients

PURPOSE

Anterior spinal fusion has become an increasingly popular technique used by orthopedic surgeons for a variety of lower spine pathology. At our institution urologists have assisted as retroperitoneal surgeons in achieving exposure of the appropriate spinal disk space. We report our experience with anterior spinal fusion in 66 patients.

MATERIALS AND METHODS

Since 1991 we have performed 66 exposures using the flank, modified Gibson, thoracoabdominal, paramedian and midline transperitoneal approaches. Exposure of each level has subtle technical issues which are reviewed.

RESULTS

During the study 34 men and 32 women 24 to 74 years old (mean age 43.8) underwent discectomy and anterior fusion of the spine. Access from T12 through L5-S1 interspace was required, and exposure of multiple spinal levels was necessary in 27. There was 1 death from massive pulmonary embolism in a patient with widely metastatic lung cancer. Retrograde ejaculation was reported by 2 men. There have been no episodes of deep or superficial wound infection and no ureteral or major vascular injuries.

CONCLUSIONS

As surgeons of the retroperitoneum urologists have an important role in providing our orthopedic colleagues with safe, adequate exposure to the anterior surface of the spine during discectomy and anterior fusion.

A comparison of multiple regimens of pneumococcal polysaccharide-meningococcal outer membrane protein complex conjugate vaccine and pneumococcal polysaccharide vaccine in toddlers

Children who had been randomized to receive one dose of either heptavalent pneumococcal polysaccharide-meningococcal outer membrane protein complex conjugate vaccine (PCV) or 23-valent pneumococcal polysaccharide vaccine (PN23) at 12, 15, or 18 months of age were subsequently randomized to receive a booster injection of either PCV or PN23 12 months later. For those children who received a priming dose of PCV (N=75) compared to PN23 (N=48) at 12, 15, or 18 months of age, higher serum antibody concentrations were achieved 1 month following a booster injection of either PCV or PN23 for all serotypes tested (p<0.001). Within the group of children receiving a priming dose of PCV, those children who received a booster dose of PN23 developed higher serum antibody concentrations for four of the seven serotypes tested and similar opsonic antibody titers to serotype 6B, yet more frequent erythema (p=0.030) and pain or soreness (p=0.024) at the injection site compared to those boosted with PCV. In conclusion, a single dose of PCV at 12-18 months of age primed for responses to booster doses of either PCV or PN23 12 months later. For those children who received a priming dose of PCV, boosting with PN23 resulted in more frequent injection site pain and erythema than boosting with PCV, yet higher antibody concentrations for most of the serotypes tested.

Molecular detection of prostate epithelial cells from the surgical field and peripheral circulation during radical prostatectomy

PURPOSE

Prostate cancer progression despite organ confined pathological assessment has been reported in a variable number of men after radical retropubic prostatectomy. To study this phenomenon, we used the prostate specific antigen (PSA) reverse transcriptase-polymerase chain reaction assay.

MATERIALS AND METHODS

We prospectively assayed the peripheral venous blood before, during and after surgical manipulation as well as the intraoperative field blood for PSA reverse transcriptase-polymerase chain reaction-positive cells in 22 men undergoing radical retropubic prostatectomy.

RESULTS

PSA reverse transcriptase-polymerase chain reaction-positive cells were identified in 20 of the 22 operative field samples (91%) and 4 of 16 (25%) had evidence of intraoperative hematogenous dissemination (p = 0.046). No significant association was identified among Gleason score, pathological stage and the PSA reverse transcriptase-polymerase chain reaction result.

CONCLUSIONS

Our results suggest that tumor cell spillage and less frequently hematogenous dissemination may be associated with operative manipulation of the prostate during radical retropubic prostatectomy and may potentially represent mechanisms of failure after radical retropubic prostatectomy.

Molecular detection of prostate epithelial cells from the surgical field and peripheral circulation during radical prostatectomy

PURPOSE

Prostate cancer progression despite organ confined pathological assessment has been reported in a variable number of men after radical retropubic prostatectomy. To study this phenomenon, we used the prostate specific antigen (PSA) reverse transcriptase-polymerase chain reaction assay.

MATERIALS AND METHODS

We prospectively assayed the peripheral venous blood before, during and after surgical manipulation as well as the intraoperative field blood for PSA reverse transcriptase-polymerase chain reaction-positive cells in 22 men undergoing radical retropubic prostatectomy.

RESULTS

PSA reverse transcriptase-polymerase chain reaction-positive cells were identified in 20 of the 22 operative field samples (91%) and 4 of 16 (25%) had evidence of intraoperative hematogenous dissemination (p = 0.046). No significant association was identified among Gleason score, pathological stage and the PSA reverse transcriptase-polymerase chain reaction result.

CONCLUSIONS

Our results suggest that tumor cell spillage and less frequently hematogenous dissemination may be associated with operative manipulation of the prostate during radical retropubic prostatectomy and may potentially represent mechanisms of failure after radical retropubic prostatectomy.

Retroperitoneal pulmonary sequestration: a rare congenital anomaly in a 71-year-old man

The suprarenal fossa is a clinically silent area of the body where nonfunctioning, indolent lesions may pass unnoticed. We report on a 71-year-old man with muscle invasive transitional cell carcinoma of the bladder who was found on staging abdominopelvic computerized tomography to have a 5 x 6 cm. left periaortic suprarenal mass. Serum analysis for a hormonally or vasoactive tumor was unrevealing. Fine needle aspiration was also nondiagnostic. An extrathoracic pulmonary sequestration was found at surgical exploration. Pulmonary sequestration rarely occurs in an extrathoracic location, is usually diagnosed in the first decade of life and to our knowledge has never been reported in this location in a patient of this age.

Use of electrocoagulation in the treatment of vesicovaginal fistulas

The role of electrocoagulation for the treatment of vesicovaginal fistulas has not been clearly defined. To determine the use of this therapeutic modality, 15 cases of fistulas treated with electrocoagulation were retrospectively reviewed. Fulguration represented the primary treatment in 12 patients and the secondary treatment in 3 after an initial attempt at open surgical closure failed. In all instances fistula size was estimated to be 3.5 mm. or less. A Bugbee electrode, which was inserted into the fistula either cystoscopically or vaginally, was used to destroy the epithelial lining of the fistula tract. Following the procedure the bladder was decompressed with a large indwelling Foley catheter for at least 2 weeks. Fulguration was successful as the sole treatment modality in 9 of 12 patients (75%) and as an alternative intervention after failure of an open surgical repair in 2 of 3 (66%). Therefore, 11 of the 15 women (73%) had complete resolution of the fistulas with this technique. We conclude that fulguration is usually effective in managing patients with vesicovaginal fistulas a few millimeters in size or less. This technique should be used as an initial treatment for appropriately selected patients and in women with small residual fistulas after open surgical failure.

Temafloxacin syndrome: review of 95 cases

Four months after its approval in the United States, temafloxacin was withdrawn from the market worldwide because of frequent reports of serious hemolysis with or without other organ system dysfunction. We describe this "temafloxacin syndrome" on the basis of a review of 95 spontaneous reports of hemolysis sent to the Food and Drug Administration. Patients typically presented with fever, chills, and jaundice a mean of 6.4 days after starting therapy. A moderate degree of hemolysis was reflected by the mean drop in hemoglobin level (by 42 g/L) and by the mean lowest concentration of hemoglobin (97 g/L). New-onset renal dysfunction was noted in 54 cases (57%), and dialysis was required in 34 cases (63%). Coagulopathy was noted in 33 cases (35%), and 48 cases (51%) met the criteria for hepatic dysfunction. Four patients developed central nervous system complications, and two patients died. Prior quinolone use was more common among patients who developed hemolysis after only one dose as opposed to two or more doses (P < .001). These data suggest that temafloxacin causes immune hemolytic anemia, most likely secondary to immune complex formation.

Reconstitution of the subclass-specific expression of CD4 in thymocytes and peripheral T cells of transgenic mice: identification of a human CD4 enhancer

During thymic maturation, CD4-CD8-TCR- immature thymocytes differentiate through a CD4+CD8+TCRlo intermediate into two functionally distinct mature T cell subsets: helper T cells expressing CD4 and a major histocompatibility complex (MHC) class II-restricted T cell receptor (TCR), and cytotoxic T cells expressing CD8 and and MHC class I-restricted TCR. The mutually exclusive expression of CD4 and CD8 is maintained in the periphery during expansion of these mature T cell subsets. To elucidate the mechanisms controlling CD4 and CD8 expression on differentiating thymocytes and mature peripheral T cells, we have examined the expression of human CD4 gene constructs in the lymphoid tissues of transgenic mice. Our analyses demonstrate that sequences contained within or closely linked to the human CD4 gene are sufficient to reconstitute the appropriate regulation of human CD4 expression on all thymocyte and mature peripheral T cell subsets. Specifically, appropriate developmental regulation was dependent on two sets of sequences, one contained within a 1.3-kb restriction fragment located 6.5 kb upstream of the human CD4 gene, and the other present within or immediately flanking the gene. Nucleotide sequence analysis identified the 1.3-kb restriction fragment as the likely human homologue of an enhancer found 13 kb upstream of the mouse CD4 transcription initiation site. The human CD4 transgenic mice provide a useful system for the identification and characterization of additional sequence elements that participate in human CD4 gene regulation and for the elucidation of regulatory mechanisms governing the developmental program mediating the maturation of the CD4+ and CD8+ peripheral T cell subsets.

Technique and complications of reconstruction of the pelvic floor with polyglactin mesh

A polyglactin mesh sling was used to reconstruct the pelvis in eight patients after colorectal or urologic resections in preparation for postoperative radiation therapy. There were three perioperative complications--a pelvic abscess requiring percutaneous drainage, a wound dehiscence and a herniation of the small intestine between the pelvic sidewall and mesh requiring small intestinal resection. There were two delayed complications, both partial small intestinal obstructions. One occurred just after the conclusion of radiation treatment and the other occurred five months after the conclusion of radiation therapy. Both obstructions responded to conservative management. None of the common acute radiation effects occurred during radiotherapy. One patient with delayed partial small intestinal obstruction had possible late radiation effects. The median follow-up period after radiation therapy was 12.5 months. Despite the complications described in this report, the use of a polyglactin mesh sling as an adjunct to resection of carcinoma of the pelvis has merit and should be studied further.

Infections of genitourinary prostheses

Infections of penile prostheses and artificial urinary sphincters are relatively rare events. Most infections are due to gram-positive bacteria such as S. epidermidis or gram-negative enteric bacteria. Most commonly, infection begins at the time of implantation, although the hematogenous route has been documented. Signs and symptoms of prosthesis infection may be obvious or subtle. Treatment of infected prostheses usually requires removal, although successful salvage procedures have been described. Prevention of infection through proper antibiotic coverage and careful attention to sterile technique results in acceptably low infection rates.

Acute intestinal pseudo-obstruction (Ogilvie's syndrome) complicating radical retropubic prostatectomy

We report 3 cases of acute colonic pseudo-obstruction in the immediate post-radical retropubic prostatectomy patient. We have not found this syndrome reported in this clinical setting, and suggest that it results from an imbalance in the autonomic innervation of the distal colon secondary to noxious afferent parasympathetic stimulation from the region of the prostate gland. Treatment guidelines are summarized stressing early recognition and conservative management of this potentially fatal complication.

Enterovesical fistula secondary to mucinous adenocarcinoma of appendix

We report an unusual case of an enterovesical fistula secondary to adenocarcinoma of the appendix.

Water imbibition in the rat prostate during castration-induced regression

The present study was conducted to examine changes in water concentration in the ventral prostate of adult rats at different intervals following castration. The prostatic dry weight was obtained by drying the fresh prostate at 70 degrees C for at least 110 hr and the prostatic water content was calculated from its wet and dry weight. Under normal conditions, the prostatic water concentration ranges from 81.9 to 82.7% in uncastrated rats. The prostatic water concentration started to increase at 8 hr postcastration (83.1%) but this increase was not statistically significant. By 16 hr postcastration, the prostatic water concentration (83.8%) became significantly higher than that of the uncastrated animals. In rats of day 1 to day 10 postcastration, the prostate contained significantly more water (84.4%-84.7%) than those in uncastrated animals. By day 21 postcastration, the prostatic water concentration (81.5%) was not significantly different from that of uncastrated rats. Unlike the prostate, the skeletal muscle did not significantly change the water concentration following castration. The 51Cr-EDTA space in the prostate was not significantly different in rats before and after castration. These results indicate that water imbibition in the rat prostate is associated with an active period of prostatic regression and that the change in the 51Cr-EDTA space during prostatic regression is not the major cause of water imbibition in the tissue. Therefore, the present findings suggest that castration-induced water imbibition in the rat prostate is caused by an increase in the intracellular water space.

Effect of local alpha-adrenergic blockade on human penile erection

Recent data suggest that selective local blockade of the alpha-adrenergic receptors of the sympathetic innervation within the corpora cavernosa of the penis will result in erection in normal and impotent subjects. To examine this hypothesis we studied in a randomized, double-blinded fashion 8 impotent patients and 2 normal controls. The organic nature of the impotence was documented with nocturnal penile tumescence testing, sacral latency examination, Doppler penile blood flow measurements, hormonal evaluation and psychological testing. The 2 normal controls had full erections for 5 to 7 minutes after the intracorporeal injection of 5 mg. phentolamine. All of the impotent subjects had tumescence without full erection after a similar injection. The tumescence was augmented by standing upright and diminished by assuming a supine posture, and lasted for several hours. Possible mechanisms, and diagnostic and therapeutic implications are discussed.

Estimation of canine prostatic size by in vivo ultrasound and volumetric measurement

Two methods for estimating the weight of the canine prostate gland in vivo were investigated. Twenty-six beagle dogs underwent transrectal and transabdominal ultrasound examination of the prostate, followed by careful, standardized caliper measurement of the prostate at surgical exploration. The prostate glands were then removed and weighed, and nomograms were constructed for use in future laboratory research. The validity of these nomograms for determining prostate weight in vivo was confirmed on evaluation of 6 additional dogs.

Fibroepithelial polyps of the ureter

We report a case of fibroepithelial polyps of the ureter, which are rare, benign mesodermal tumors. The advantage of ureteroscopic confirmation of this benign tumor is emphasized.

An assessment of the treatment needs of Vietnam-era veterans

A needs assessment was conducted to determine the existence and extent of differences between Vietnam-era veterans and other veterans residing within the catchment area of the Northport Veterans Administration Medical Center. The results of a questionnaire completed by 486 veterans indicated that, compared with World War II and Korean War veterans, a greater percentage of Vietnam-era veterans reported experiencing the symptoms of posttraumatic stress disorder. They also reported more situational adjustment problems. A great number of Vietnam-era veterans expressed a need for psychotherapy and anger-control therapy, and they generally preferred to be treated with other Vietnam-era veterans who have had similar combat experience.