Background
Standard treatment for glioblastoma is radiation with concomitant and adjuvant temozolomide for 6 cycles, although the optimal number of cycles of adjuvant temozolomide has long been a subject of debate. We performed a phase II randomized trial investigating whether extending adjuvant temozolomide for more than 6 cycles improved outcome.
Methods
Glioblastoma patients treated at 20 Spanish hospitals who had not progressed after 6 cycles of adjuvant temozolomide were centrally randomized to stop (control arm) or continue (experimental arm) temozolomide up to a total of 12 cycles at the same doses they were receiving in cycle 6. Patients were stratified by MGMT methylation and measurable disease. The primary endpoint was differences in 6-month progression-free survival (PFS). Secondary endpoints were PFS, overall survival (OS), and safety (Clinicaltrials.gov NCT02209948).
Results
From August 2014 to November 2018, 166 patients were screened, 7 of whom were ineligible. Seventy-nine patients were included in the stop arm and 80 in the experimental arm. All patients were included in the analyses of outcomes and of safety. There were no differences in 6-month PFS (control 55.7%; experimental 61.3%), PFS, or OS between arms. MGMT methylation and absence of measurable disease were independent factors of better outcome. Patients in the experimental arm had more lymphopenia (P < 0.001), thrombocytopenia (P < 0.001), and nausea and vomiting (P = 0.001).
Conclusions
Continuing temozolomide after 6 adjuvant cycles is associated with greater toxicity but confers no additional benefit in 6-month PFS.
Key Points
1. Extending adjuvant temozolomide to 12 cycles did not improve 6-month PFS.
2. Extending adjuvant temozolomide did not improve PFS or OS in any patient subset.
3. Extending adjuvant temozolomide was linked to increased toxicities.
The crystal structure of the C-terminal domain III of Pseudomonas aeruginosa TolA has been determined at 1.9 A Ê resolution. The fold is similar to that of the corresponding domain of Escherichia coli TolA, despite the limited amino acid sequence identity of the two proteins (20%). A pattern was discerned that conserves the fold of domain III within the wider TolA family and, moreover, reveals a relationship between TolA domain III and the C-terminal domain of the TonB transporter proteins. We propose that the TolA and TonB C-terminal domains have a common evolutionary origin and are related by means of domain swapping, with interesting mechanistic implications. We have also determined the overall shape of the didomain, domains II + III, of P.aeruginosa TolA by solution X-ray scattering. The molecule is monomericÐits elongated, stalk shape can accommodate the crystal structure of domain III at one end, and an elongated helical bundle within the portion corresponding to domain II. Based on these data, a model for the periplasmic domains of P.aeruginosa TolA is presented that may explain the inferred allosteric properties of members of the TolA family. The mechanisms of TolA-mediated entry of bateriophages in P.aeruginosa and E.coli are likely to be similar.
MYC protein expression detected by immunohistochemistry using a commercially available antibody correlates with MYC gene translocation, and could be used as a screening tool to select those cases in which confirmatory genetic testing is mandatory.
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