Citations

Purpose A traditional end point for colon adjuvant clinical trials is overall survival (OS), with 5 years demonstrating adequate follow-up. A shorter-term end point providing convincing evidence to allow treatment comparisons could significantly speed the translation of advances into practice. Methods Individual patient data were pooled from 18 randomized phase III colon cancer adjuvant clinical trials. Trials included 43 arms, with a pooled sample size of 20,898 patients. The primary hypothesis was that disease-free survival (DFS), with 3 years of follow-up, is an appropriate primary end point to replace OS with 5 years of follow-up. Results The recurrence rates for years 1 through 5 were 12%, 14%, 8%, 5%, and 3%, respectively. Median time from recurrence to death was 12 months. Eighty percent of recurrences were in the first 3 years; 91% of patients with recurrence by 3 years died before 5 years. Correlation between 3-year DFS and 5-year OS was 0.89. Comparing control versus experimental arms within each trial, the correlation between hazard ratios for DFS and OS was 0.92. Within-trial log-rank testing using both DFS and OS provided the same conclusion in 23 (92%) of 25 cases. Formal measures of surrogacy were satisfied. Conclusion In patients treated on phase III adjuvant colon clinical trials, DFS and OS are highly correlated, both within patients and across trials. These results suggest that DFS after 3 years of median follow-up is an appropriate end point for adjuvant colon cancer clinical trials of fluorouracil-based regimens, although marginally significant DFS improvements may not translate into significant OS benefits.

Frontotemporal dementia with parkinsonism linked to chromosome 17 (FTDP-17) is caused by mutations in the gene encoding the microtubule-associated protein, tau. Some FTDP-17 mutations affect exon 10 splicing. To correct aberrant exon 10 splicing while retaining endogenous transcriptional control, we evaluated the feasibility of using spliceosome-mediated RNA trans-splicing (SMaRT) to reprogram tau mRNA. We designed a pre-trans-splicing molecule containing human tau exons 10 to 13 and a binding domain complementary to the 3′ end of tau intron 9. A minigene comprising tau exons 9, 10, and 11 and minimal flanking intronic sequences was used as a target. RT-PCR analysis of SH-SY5Y cells or COS cells cotransfected with a minigene and a pre-trans-splicing molecule using primers to opposite sides of the predicted splice junction generated products containing exons 9 to 13. Sequencing of the chimeric products showed that an exact exon 9–exon 10 junction had been created, thus demonstrating that tau RNA can be reprogrammed by trans-splicing. Furthermore, by using the same paradigm with a minigene containing full-length intronic sequences, we show that cis-splicing exclusion of exon 10 can be by-passed by trans-splicing and that conversion of exon 10 – tau RNA into exon 10 + tau RNA could be achieved with ≈34% efficiency. Our results demonstrate that an alternatively spliced exon can be replaced by trans-splicing and open the way to novel therapeutic applications of SMaRT for tauopathies and other disorders linked to aberrant alternative splicing.

Distortion product otoacoustic emission (DPOAE) input/output functions were measured at nine f2 frequencies ranging from 500 to 8000 Hz in 210 normal-hearing and hearing-impaired subjects. In a companion paper [Stover et al., J. Acoust. Soc. Am. 100, 956–967 (1996)], L1−L2 was held constant at 10 dB, and L2 was varied from 65 to 10 dB SPL in 5-dB steps. Based upon analyses using clinical decision theory, it was demonstrated that DPOAE amplitudes for 65/55 dB SPL primaries (L1/L2) and DPOAE thresholds resulted in the greatest separation between normal and impaired ears. In this paper, the data for these two conditions were recast as cumulative distributions, which not only describe the extent of overlap between normal and impaired distributions, but also provide the measured value (i.e., the specific DPOAE amplitude or threshold) for any combination of hit and false alarm rates. From these distributions, confidence limits were constructed for both DPOAE amplitude and threshold to determine the degree of certainty with which any measured response could be assigned to either the normal or impaired population. For these analyses, DPOAE measurements were divided into three categories (a) response properties that would be unlikely to come from normal ears, (b) response properties that would be unlikely to come from impaired ears, and (c) response properties for which hearing status was uncertain. Based upon DPOAE amplitude measurements, the region of uncertainty, defined between the 95 percentile for impaired ears and the 5 percentile for normal ears, was relatively narrow for f2 frequencies ranging from 707 to 4000 Hz. For DPOAE thresholds, this region was relatively narrow for f2 frequencies ranging from 1414 to 4000 Hz.

This study examined the effect of primary stimulus level on the ability of distortion product otoacoustic emission (DPOAE) measurements to separate normal-hearing from hearing-impaired ears. Complete I/O functions were obtained for nine f2 frequencies on 210 people approximately evenly divided between normal hearing and hearing impaired. Clinical decision theory was used to assess both DPOAE amplitudes and DPOAE threshold as diagnostic indicators of hearing status. Moderate level primary stimuli elicited responses that separated normal from impaired better than either lower level or higher level stimuli. The two populations were differentiated for all frequencies above 500 Hz by DPOAE amplitude, given primary levels, L1 and L2, of 65 and 55 dB SPL. DPOAE threshold performed equally well, but threshold ambiguity in noise and longer testing times make it a less suitable DPOAE measure to use diagnostically.

Policy has not adequately addressed the unique circumstances of pediatric subspecialties, many of which are facing workforce shortages. Pediatric subspecialties, which we define to include all medical and surgical subspecialties, are discrete disciplines that differ significantly from each other and from adult medicine subspecialties. Concerns about a current shortage of pediatric subspecialists overall are driven by indicators ranging from recruitment difficulties to long wait times for appointments. The future supply of pediatric subspecialists and patient access to pediatric subspecialty care will be affected by a number of key factors or forces for change. We discuss 5 of these factors: changing physician and patient demographics; debt load and lifestyle considerations; competition among providers of subspecialty care; equitable reimbursement for subspecialty services; and policy to regulate physician supply. We also identify issues and strategies that medical and specialty societies, pediatric subspecialists, researchers, child advocates, policy makers, and others should consider in the development of subspecialty-specific workforce-policy agendas.

Abstract Purpose: Most colorectal cancers that have high levels of microsatellite instability (MSI-H) show loss of immunohistochemical expression of proteins that participate in the DNA mismatch repair process, most often involving MLH1 and MSH2. Less commonly, a third DNA mismatch repair protein, MSH6, may also be lost as the primary event. Rarely, tumors with MSI-H show normal expression of these three proteins. The genetic deficiency leading to the MSI-H phenotype in such cases is unknown. PMS2 is another member of the DNA mismatch repair complex. Its expression is generally lost in tumors with MLH1 loss of expression. Rarely, there is selective loss of PMS2 expression. We sought to describe the frequency and clinical correlates of selective loss of expression of PMS2 with the MSI-H tumor phenotype. Experimental Design: Two thousand seven hundred nineteen colorectal cancers from both clinic- and research-based ascertainment were studied. Tumor MSI testing and immunohistochemistry for MLH1, MSH2, MSH6, and PMS2 were conducted. Medical records were abstracted for age at diagnosis, gender, colorectal cancer site, and family history. Results: Five hundred thirty-five of the 2,719 tumors were MSI-H. Of these, 93% showed loss of expression of MLH1, MSH2, and/or MSH6. Thirty-eight showed normal expression for these proteins. PMS2 immunohistochemical staining was successful in 32 of 38 of these tumors. Of the 32, 23 showed selective loss of expression of PMS2. This was associated with young age of diagnosis and right-sided location but not with a striking family history of cancer. Conclusions: Overall, 97% of the MSI-H tumors showed loss of expression for one or more of these four mismatch repair proteins. Selective loss of expression of PMS2 was present in 72% of cases in which colorectal cancers had an MSI-H phenotype but no alteration of expression of MLH1, MSH2, and MSH6. The underlying mechanism involved cannot be determined from this study but could involve point mutations in other DNA mismatch repair genes with retention of immunohistochemical expression, somatic inactivation of PMS2, or germ line mutation of PMS2.

Abstract Purpose: Epithelial ovarian cancers are thought to arise from flattened epithelial cells that cover the ovarian surface or that line inclusion cysts. During malignant transformation, different histotypes arise that resemble epithelial cells from normal fallopian tube, endometrium, and intestine. This study compares gene expression in serous, endometrioid, clear cell, and mucinous ovarian cancers with that in the normal tissues that they resemble. Experimental Design: Expression of 63,000 probe sets was measured in 50 ovarian cancers, in 5 pools of normal ovarian epithelial brushings, and in mucosal scrapings from 4 normal fallopian tube, 5 endometrium, and 4 colon specimens. Using rank-sum analysis, genes whose expressions best differentiated the ovarian cancer histotypes and normal ovarian epithelium were used to determine whether a correlation based on gene expression existed between ovarian cancer histotypes and the normal tissues they resemble. Results: When compared with normal ovarian epithelial brushings, alterations in serous tumors correlated with those in normal fallopian tube (P = 0.0042) but not in other normal tissues. Similarly, mucinous cancers correlated with those in normal colonic mucosa (P = 0.0003), and both endometrioid and clear cell histotypes correlated with changes in normal endometrium (P = 0.0172 and 0.0002, respectively). Mucinous cancers displayed the greatest number of alterations in gene expression when compared with normal ovarian epithelial cells. Conclusion: Studies at a molecular level show distinct expression profiles of different histologies of ovarian cancer and support the long-held belief that histotypes of ovarian cancers come to resemble normal fallopian tube, endometrial, and colonic epithelium. Several potential molecular markers for mucinous ovarian cancers have been identified.