Local Time-to-Event Endpoint Under-Reporting and Variability in Pancreatic Cancer Trials Involving Radiotherapy

PURPOSE/OBJECTIVE(S)

The role of radiotherapy (RT) for pancreatic adenocarcinoma (PDAC) remains controversial, with recent studies showing conflicting results. Importantly, endpoints used to evaluate efficacy in recent RT trials for PDAC have been highly variable. As variability in time-to-event (TTE) endpoint definitions is demonstrated to influence outcomes in other cancers, it is critical that radiation oncologists develop consensus around optimal endpoint definitions to use in future PDAC trial design. Thus, we conducted a systematic review of PDAC trials involving RT to characterize the frequency and variability in local TTE endpoint reporting.

MATERIALS/METHODS

An electronic database search was conducted of PubMed, EMBASE, and Cochrane Library to identify phase 2 and 3 clinical trials published from 2010-2022 of localized PDAC involving RT that reported any TTE endpoint (e.g., local control). After excluding duplicates, two independent reviewers screened full-text manuscripts for inclusion. Trial characteristics and local TTE endpoints/definitions were tabulated.

RESULTS

Three hundred twenty references were screened and 79 trials were included, of which 73 (92%) were phase 2 and 26 (33%) were randomized. Twenty (25%) trials reported a local TTE endpoint; these were local control (LC; N = 6), local progression-free survival (LPFS; N = 4), freedom from local progression (N = 6), locoregional progression-free interval (N = 1), cumulative incidence of local recurrence (N = 1), time to failure of sustained LC (N = 1), and local disease-free survival (N = 1). LC (N = 6) had 5 unique definitions and was undefined once; 1 definition included death as an event. LPFS (N = 4) had 3 definitions; 2 did not consider death an event. Among trials with local TTE endpoints, 9 trials specified the definition of a local recurrence/progression. Four trials defined local recurrence based on RT volumes; one counted clinical evidence of recurrence (e.g., tumor bleed); and one counted a rise in tumor markers without evidence of distant metastases. The index time ("time-zero") was defined for local TTE endpoints in 10 trials, including start of RT (N = 4) or chemo (N = 1), end of RT (N = 1), diagnosis (N = 1), enrollment (N = 1), and time of surgery (N = 1).

CONCLUSION

Few pancreatic cancer trials involving RT report local TTE endpoints, with significant heterogeneity in endpoints used and their definitions. Development of consensus endpoint definitions will be critical for future PDAC trial design.

Glucagon-like peptide-1 receptor expression in Xenopus oocytes stimulates inositol trisphosphate-dependent intracellular Ca2+ mobilization

The signal transduction pathway of the cloned human glucagon-like peptide-1 (GLP-1) receptor was studied in voltage-clamped Xenopus oocytes. Binding of GLP-1(7-36)amide was associated with cAMP production, increased [Ca2+]i and activation of Ca2+-dependent Cl- current. The effect of GLP-1(7-36)amide reflects intracellular Ca2+ mobilization and was suppressed by injection of the Ca2+ chelator BAPTA and the inositol trisphosphate receptor antagonist heparin. The responses were not mimicked by the adenylate cyclase activator forskolin and unaffected by the protein kinase A (PKA) inhibitor Rp-cAMPS. We conclude that GLP-1 receptor expression in Xenopus oocytes evokes inositol trisphosphate-dependent intracellular Ca2+ mobilization independent of the cAMP/PKA signaling pathway.

Antagonist properties of a phosphono isoxazole amino acid at glutamate R1-4 (R,S)-2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid receptor subtypes

The activity of the (R, S)-2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid (AMPA) receptor antagonist, (R,S) -2-amino-3-[5-tert-butyl-3-(phosphonomethoxy)-4-isoxazolyl] propionic acid (ATPO), at recombinant ionotropic glutamate receptors (GluRs) was evaluated using electrophysiological techniques. Responses at homo- or heterooligomeric AMPA-preferring GluRs expressed in human embryonic kidney (HEK) 293 cells (GluR1-flip) or Xenopus laevis oocytes (GluR1-4-flop or GluR1-flop + GluR2) were potently inhibited by ATPO with apparent dissociation constants (Kb values) ranging from 3.9 to 26 microM. A Schild analysis for kainate (KA)-activated GluR1 receptors showed ATPO to have a KB of 8.2 microM and a slope of unity, indicating competitive inhibition. The antagonism by ATPO at GluR1 was of similar magnitude at holding potentials between -100 mV and +20 mV. In contrast, ATPO (<300 microM), does not inhibit responses to kainate at homomeric GluR6 or heterooligomeric GluR6/KA2 expressed in HEK 293 cells but activated GluR5 and GluR5/KA2 expressed in X. laevis oocytes. ATPO produced <15% inhibition at the maximal concentration (300 microM) of current responses through NR1A + NR2B receptors expressed in X. laevis oocytes. Thus, ATPO shows a unique pharmacological profile, being an antagonist at GluR1-4 and a weak partial agonist at GluR5 and GluR5/KA2.

Engineered RNA-mediated resistance to tomato spotted wilt virus is sequence specific

Transgenic plants were produced that expressed a wide range of randomly chosen sequences of the tripartite tomato spotted wilt virus (TSWV) RNA genome or its complement. Testing the progenies of these plants revealed that only transgenic expression of N or NS(M) gene sequences resulted in resistance to TSWV.

Ultrasonography versus urography as preoperative investigation prior to hysterectomy

Ultrasonography (US) has been compared with urography (IVU) as a preoperative investigation prior to hysterectomy in 62 patients. In 38 patients the urinary tract was deemed normal by both US and IVU. US and IVU coincided in varying degrees of hydronephrosis in 8 patients and disagreed in one. Of 5 double ureters, US missed 2. IVU showed expansile lesions in 5 kidneys where US showed benign cysts. No severe contrast media reactions were observed. We recommend that preoperative urography should be replaced by preoperative ultrasonography when a screening examination of the upper urinary tract morphology is deemed necessary prior to hysterectomy.

Percutaneous antegrade dilatation of distal ureteral strictures and obstructions

Since the first ureteral dilatations in experimental dogs were performed, the technique in human has been accepted and improved over the years. Balloon dilatation has been successful, but it has been very difficult or impossible to force the guide wires through long total strictures, especially those localized distally. In order to recanalize very narrow strictures or total occlusions located in the distal ureter, a modified angiographic technique was developed and tested in 12 ureters in 10 patients.

Central venous catheter with subcutaneous injection port (Port-A-Cath): clinical experience with children

Long-term intermittent venous access was established in 26 children by means of a central venous catheter (CVC) with a subcutaneous injection port (Port-A-Cath) (PAC). As of December, 1985, PACs had been in place for 20-750 days (cumulative 10,890 days) with 647 entries into the system. The PACs were used for blood sampling and administration of chemotherapy, antibiotics, fluids, total parenteral nutrition (TPN), and blood products. One patient with sever neutropenia (absolute neutrophil granulocyte count [ANC] less than 0.1 x 10(9)/L) at the time of the PAC implant developed an infection around the port after 2 days, with subsequent septicemia (Bacillus cereus) necessitating removal of the PAC. Otherwise, no definite PAC-related infections occurred, including 258 days of neutropenia (ANC less than 0.5 x 10(9)/L). Two PACs were found occluded with greyish deposits of fat and organic material after long-term (45 and 61 days) continuous TPN and were removed. Malposition of catheter, extravasation, thrombosis, and other potential technical or psychological complications were not observed. The children continued normal activities, and the easy venous access decreased emotional stress during treatment. Local doctors were trained to use the PACs, with which they administered maintenance chemotherapy. We conclude that the use of PACs in children is safe, even in the first year of life, and has many advantages when compared with other CVCs currently in use. Strict indications, meticulous implantation technique, and adequate handling are, however, mandatory.

Mast cells in the tubal wall in women using an intrauterine contraceptive device

The number of mast cells in the tubal wall of 33 healthy nonpregnant women, 17 of whom had an intrauterine contraceptive device (IUCD), was investigated. Light microscopy showed that both the muscularis externa and the lamina propria of the tubal wall contained more mast cells in the 17 IUCD users than in the 16 non-users (control group). In both patient groups the mast cell concentration was higher in the muscularis externa than in the lamina propria. Most mast cells of the muscularis externa were more closely related to smooth muscle cells than to blood vessels. The increased number of mast cells in IUCD users may be a factor in the pathogenesis of pelvic inflammatory disease and the ectopic pregnancies that occur in IUCD users.

Low risk of pelvic inflammatory disease in young never-pregnant women using Gravigard

The present four-center investigation involves 516 never-pregnant women in whom a copper-7-intrauterine device (Cu-7-IUD) was inserted. Out of these patients 173 were teenagers at the time of insertion. A "small-sized" Cu-7-IUD (Cu-7-Nullip) - designed for nulliparous women - was randomely used instead of the commercially available Cu-7-IUD (GravigardR) in 76 - 44 of whom were teenagers - out of the 516 women. The incidence of pelvic inflammatory disease (PID) of 9,080 woman-months was reviewed. In the present study the incidence of PID varied from one center to another between 0.9 and 1.4 per cent/year in women wearing Cu-IUDs. When comparing these figures with the estimated incidence (1.2%) in the population of fertile-aged women, it was concluded that the risk for PID was not increased in never-pregnant women using Cu-IUDs, including teenagers as well as women of 20 years of age or more. No difference in the incidence of PID was observed between the GravigardR and the Cu-7 Nullip.