Docetaxel-oxaliplatin-capecitabine/5-fluorouracil (DOX/F) followed by docetaxel versus oxaliplatin-capecitabine/5-fluorouracil (CAPOX/FOLFOX) in HER2-negative advanced gastric cancers.

BACKGROUND: We evaluated whether the addition of docetaxel (D) to a combination comprising 5-fluorouracil/leucovorin (5-FU/LV) or capecitabine (C) plus oxaliplatin (O) (DOF/DOX) improved overall survival (OS) compared with 6 months of 5-fluorouracil (5-FU) or capecitabine in combination with oxaliplatin (FOLFOX/CAPOX) alone in advanced HER2-negative gastroesophageal junction and gastric adenocarcinomas (G/GEJ). METHODS: This study was an investigator-initiated, open-label, multi-institutional, randomized phase III trial in adult patients with HER2-negative advanced G/GEJs. The primary endpoint of the study was a comparison of median OS by Kaplan-Meier method. Next-generation sequencing was performed on tissue. RESULTS: Of the 324 patients randomly assigned between July 2020 and November 2022, 305 patients were evaluable for analysis (FOLFOX/CAPOX: 156; DOF/DOX: 149). With a median follow-up time of 19.2 months (95% Confidence Interval [CI] = 16.5 months to 21.9 months) for the entire cohort, the median OS was 10.1 months (95% CI = 9.2 to 10.9) for FOLFOX/CAPOX and 8.9 months (95% CI = 7.3 to 10.5) for DOF/DOX, and this difference was not statistically significant (P = .70). An increased proportion of grade 3 or grade 4 neutropenia (21% vs 3%; P < .001) and grade 2/3 neuropathy (17% vs 7%; P = .005) was seen in patients receiving DOF/DOX. Genomic profiling revealed a low incidence of microsatellite instability (1%) and a high incidence of BRCA1 (8.4%) and BRCA2 (7.5%) somatic alterations. CONCLUSION: FOLFOX or CAPOX chemotherapy for 6 months remains one of the standards of care in advanced HER2-negative gastroesophageal junction and gastric adenocarcinomas, with no additional survival benefit seen with the addition of docetaxel. Genomic profiling of patients revealed a higher than previously known incidence of somatic BRCA alterations, which requires further evaluation.CTRI (Clinical Trial Registry of India: CTRI/2020/03/023944).

Design of the elusive proteinaceous oxygen donor copper site suggests a promising future for copper for MRI contrast agents.

We report the preparation and spectroscopic characterization of a highly elusive copper site bound exclusively to oxygen donor atoms within a protein scaffold. Despite copper generally being considered unsuitable for use in MRI contrast agents, which in the clinic are largely Gd(III) based, the designed copper coiled coil displays relaxivity values equal to, or superior than, those of the Gd(III) analog at clinical field strengths. The creation of this new-to-biology proteinaceous CuOx-binding site demonstrates the power of the de novo peptide design approach to access chemistry for abiological applications, such as for the development of MRI contrast agents.

A Gadolinium Spin Label with Both a Narrow Central Transition and Short Tether for Use in Double Electron Electron Resonance Distance Measurements.

The design, synthesis, and application of a nine-coordinate gadolinium(III)-containing spin label, [Gd.sTPATCN]-SL, for use in nanometer-distance measurement experiments by EPR spectroscopy is presented. The spin label links to cysteines via a short thioether tether and has a narrow central transition indicative of small zero-field splitting (ZFS). A protein homodimer, TRIM25cc, was selectively labeled with [Gd.sTPATCN]-SL (70%) and a nitroxide (30%) under mild conditions and measured using the double electron electron resonance (DEER) technique with both commercial Q-band and home-built W-band spectrometers. The label shows great promise for increasing the sensitivity of DEER measurements through both its favorable relaxation parameters and the large DEER modulation depth at both Q- and W-band for the inter-Gd(III) DEER measurement which, at 9%, is the largest recorded under these conditions.

ATP-induced asymmetric pre-protein folding as a driver of protein translocation through the Sec machinery.

Transport of proteins across membranes is a fundamental process, achieved in every cell by the 'Sec' translocon. In prokaryotes, SecYEG associates with the motor ATPase SecA to carry out translocation for pre-protein secretion. Previously, we proposed a Brownian ratchet model for transport, whereby the free energy of ATP-turnover favours the directional diffusion of the polypeptide (Allen et al., 2016). Here, we show that ATP enhances this process by modulating secondary structure formation within the translocating protein. A combination of molecular simulation with hydrogendeuterium-exchange mass spectrometry and electron paramagnetic resonance spectroscopy reveal an asymmetry across the membrane: ATP-induced conformational changes in the cytosolic cavity promote unfolded pre-protein structure, while the exterior cavity favours its formation. This ability to exploit structure within a pre-protein is an unexplored area of protein transport, which may apply to other protein transporters, such as those of the endoplasmic reticulum and mitochondria.

Distance Measurement of a Noncovalently Bound Y@C82 Pair with Double Electron Electron Resonance Spectroscopy.

Paramagnetic endohedral fullerenes with long spin coherence times, such as N@C60 and Y@C82, are being explored as potential spin quantum bits (qubits). Their use for quantum information processing requires a way to hold them in fixed spatial arrangements. Here we report the synthesis of a porphyrin-based two-site receptor 1, offering a rigid structure that binds spin-active fullerenes (Y@C82) at a center-to-center distance of 5.0 nm, predicted from molecular simulations. The spin-spin dipolar coupling was measured with the pulsed EPR spectroscopy technique of double electron electron resonance and analyzed to give a distance of 4.87 nm with a small distribution of distances.