Four-year overall survival update from the phase III HIMALAYA study of tremelimumab plus durvalumab in unresectable hepatocellular carcinoma

BACKGROUND

In the phase III HIMALAYA study (NCT03298451) in unresectable hepatocellular carcinoma (uHCC), STRIDE (Single Tremelimumab Regular Interval Durvalumab) significantly improved overall survival (OS) versus sorafenib; durvalumab monotherapy was noninferior to sorafenib for OS. Results reported herein are from a 4-year updated OS analysis of HIMALAYA.

PATIENTS AND METHODS

Participants with uHCC and no previous systemic treatment were randomized to STRIDE (n = 393), durvalumab (n = 389), or sorafenib (n = 389). The updated data cut-off was 23 January 2023. OS and serious adverse events (AEs) were assessed. Additionally, baseline characteristics and subsequent therapies were analyzed in long-term survivors (≥36 months beyond randomization).

RESULTS

For STRIDE, durvalumab, and sorafenib, median [95% confidence interval (CI)] follow-up was 49.12 months (46.95-50.17 months), 48.46 months (46.82-49.81 months), and 47.31 months (45.08-49.15 months), respectively. OS hazard ratio (95% CI) for STRIDE versus sorafenib was 0.78 (0.67-0.92). The 36-month OS rate for STRIDE was 30.7% versus 19.8% for sorafenib. The 48-month OS rate remained higher for STRIDE at 25.2%, versus 15.1% for sorafenib. The long-term OS benefit of STRIDE was observed across clinically relevant subgroups and was further improved in participants who achieved disease control. Long-term survivors with STRIDE (n = 103) included participants across clinically relevant subgroups, and 57.3% (59/103) had no reported subsequent anticancer therapy. No new serious treatment-related AEs occurred with STRIDE from the primary analysis (17.5%; 68/388). Durvalumab maintained OS noninferiority to sorafenib and no late-onset safety signals were identified.

CONCLUSIONS

These data represent the longest follow-up to date in phase III studies in uHCC. The unprecedented 3- and 4-year OS rates reinforce the sustained long-term OS benefit of STRIDE versus sorafenib. STRIDE maintained a tolerable yet differentiated safety profile from other current uHCC therapies. Results continue to support the long-term benefits of STRIDE in a diverse population, reflective of uHCC globally.

Exploring helix structures of γ-peptides based on 2-(aminomethyl)cyclopentanecarboxylic acid

Conformational search and density functional theory calculations were performed to explore the preferences of helical structures for chiro-specific oligo-γ-peptides of 2-(aminomethyl)cyclopentanecarboxylic acid (γAmc5 ) with a cyclopentyl constraint on the Cα -Cβ bond in solution. The dimer and tetramer of γAmc5 (1) with homochiral (1S, 2S) configurations exhibited a strong preference for the 9-membered helix foldamer in solution, except for the tetramer in water. However, the oligomers of γAmc5 (1) longer than tetramer preferentially adopted a right-handed (P)-2.614 -helix (H1 -14) as the peptide sequence becomes longer and as solvent polarity increases. The high stabilities for H1 -14 foldamers of γAmc5 (1) in solution were ascribed to the favored solvation free energies. The calculated mean backbone torsion angles for H1 -14 helix foldamers of γAmc5 (1) were similar to those calculated for oligomers of other γ-residues with cyclopentane or cyclohexane rings. However, the substitution of cyclopentane constraints on the Cα -Cβ bond of the γAmc5 (1) residue resulted in different conformational preferences and/or handedness of helix foldamers. In particular, the pyrrolidine-substituted analogs of the H1 -14 foldamers of γAmc5 (1) with adjacent amine diads substituted at a proximal distance are expected to be potential catalysts for the crossed aldol condensation in nonpolar and polar solvents.

[Application value of DNA damage repair variants in adjuvant therapy of triple negative breast cancer]

Objective: To investigate the correlation between adjuvant chemotherapy with platinum-containing regimens and DNA damage repair (DDR) defects in early-stage triple negative breast cancer (TNBC), and to provide a basis for precise treatment of TNBC. Methods: Next-generation sequencing (NGS) testing was performed on postoperative breast cancer specimens selected from the Cancer Hospital of Chinese Academy of Medical Sciences from June 2009 to October 2015 to analyze the correlation between DDR gene variants and the efficacy of adjuvant chemotherapy with TNBC platinum-containing regimens, and thus to screen the superior population for adjuvant chemotherapy with TNBC platinum-containing regimens. The study used t-test, χ(2) test, Fisher's exact test, rank sum test and multifactorial logistic analysis to assess the associations between mutated genes and clinicopathological characteristics and prognosis, and Log-rank test and Cox proportional risk model were used for survival and correlation analysis. Results: NGS results were successfully obtained in 149 patients (74 in the platinum-containing group and 75 in the platinum-free group), with a 97.3% (145/149) DDR gene mutation rate and a median number of 4 mutations in all patients. 5-year disease-free survival (DFS) was 85.4% and 75.0% for patients with DDR gene mutations and DDR gene wild-type, respectively, without statistical difference (P=0.825). The 5-year DFS rates of patients with homologous recombination repair (HRR) pathway mutation were 84.6% in platinum-containing (TCb) group and 84.9% in platinum-free (EC-T) group (P=0.554), respectively. The 5-year DFS rates of patients with and without mutations in the platinite-containing HRR pathway were 84.9% and 85.0%, respectively (P=0.751). The number of DDR pathways with mutations and the number of DDR gene mutations were not associated with prognosis (both P>0.05). PIK3CA mutation patients in TCb group had a worse prognosis than wild-type patients (5-year DFS were 71.4% and 88.1%, P=0.037), and KMT2D mutation patients in EC-T group had a worse prognosis than wild-type patients (5-year DFS were 76.9% and 86.8%, P=0.039). Conclusions: DDR gene variation is common in TNBC, more clinical studies are needed to prove whether DDR variation can serve as effective biomarkers for treatment with platinum.

Fiber reinforced hydrated networks recapitulate the poroelastic mechanics of articular cartilage

The role of poroelasticity on the functional performance of articular cartilage has been established in the scientific literature since the 1960s. Despite the extensive knowledge on this topic there remain few attempts to design for poroelasticity and to our knowledge no demonstration of an engineered poroelastic material that approaches the physiological performance. In this paper, we report on the development of an engineered material that begins to approach physiological poroelasticity. We quantify poroelasticity using the fluid load fraction, apply mixture theory to model the material system, and determine cytocompatibility using primary human mesenchymal stem cells. The design approach is based on a fiber reinforced hydrated network and uses routine fabrication methods (electrohydrodynamic deposition) and materials (poly[ɛ-caprolactone] and gelatin) to develop the engineered poroelastic material. This composite material achieved a mean peak fluid load fraction of 68%, displayed consistency with mixture theory, and demonstrated cytocompatibility. This work creates a foundation for designing poroelastic cartilage implants and developing scaffold systems to study chondrocyte mechanobiology and tissue engineering. STATEMENT OF SIGNIFICANCE: Poroelasticity drives the functional mechanics of articular cartilage (load bearing and lubrication). In this work we develop the design rationale and approach to produce a poroelastic material, known as a fiber reinforced hydrated network (FiHy™), that begins to approach the native performance of articular cartilage. This is the first engineered material system capable of exceeding isotropic linear poroelastic theory. The framework developed here enables fundamental studies of poroelasticity and the development of translational materials for cartilage repair.

Impact of aza-substitutions on the preference of helix handedness for β-peptide oligomers: a DFT study

We studied the helix preference of the heterochiral pentamers of cis-2-aminocyclohexanecarboxylic acid (c-ACHC) and cis-2-aminocyclopentanecarboxylic acid (c-ACPC) with alternating backbone configurations by replacing C^β-aza- or C^α-aza-peptide residues using DFT methods in solution. The helix-handedness preferences of two pentamers were strongly affected by the replacement positions (i.e., chiralities) but not depending on the solvent polarity.

Exploring Conformational Preferences of Leu-enkephalin Using the Conformational Search and Double-Hybrid DFT Energy Calculations

The conformational preferences of Leu-enkephalin (Leu-Enk) were explored by the conformational search and density functional theory (DFT) calculations. By a combination of low-energy conformers of each residue, the initial structures of the neutral Leu-Enk were generated and optimized using the ECEPP3 force field in the gas phase. These structures were reoptimized at the HF/3-21G(d) and M06-2X levels of theory with 6-31G(d) and 6-31+G(d) basis functions. We finally located the 139 structures with the relative energy <10 kcal mol^-1 in the gas phase, from which the structures of the corresponding zwitterionic Leu-Enk were generated and reoptimized at the M06-2X/6-31+G(d) level of theory using the implicit solvation model based on density (SMD) in water. The conformational preferences of Leu-Enk were analyzed using Gibbs free energies corrected by single-point energies calculated at the double-hybrid DSD-PBEP86-D3BJ/def2-TZVP level of theory in the gas phase and in water. The neutral Leu-Enk dominantly adopted a folded structure in the gas phase stabilized by three H-bonds with a βII'-bend-like motif at the Gly3-Phe4 sequence and a close contact between the side chains of Phe4 and Leu5. The zwitterionic Leu-Enk exhibited a folded structure in water stabilized by three H-bonds with double β-bends such as a βII' bend at the Gly2-Gly3 sequence and a βI bend at the Gly3-Phe4 sequence. The calculated ensemble-averaged distance between C_Gly2 ^α and C_Leu5 ^α of the zwitterionic Leu-Enk in water is consistent with the value estimated from the simulated annealing using the distance constraints derived from nuclear Overhauser effect spectroscopy (NOESY) spectra in water. Interestingly, the preferred conformations of the neutral and zwitterionic Leu-Enk are new folded structures not predicted by earlier computational studies. According to the refined model of the zwitterionic Leu-Enk bound to δ-opioid receptor (δOR), there were favorable interactions of the terminal charged groups of Leu-Enk with the side chains of charged residues of δOR as well as a favorable C_Aryl···H interaction of the Phe4 residue of Leu-Enk with Trp284 of δOR. Hence, these favorable interactions would induce the folded structure of the zwitterionic Leu-Enk with double β-bends isolated in water into the "bioactive conformation" like an extended structure when binding to δOR.

Exploring Helical Folding in Oligomers of Cyclopentane-Based ϵ-Amino Acids: A Computational Study

Invited for this month's cover picture is the group of Young Kee Kang at Chungbuk National University (Republic of Korea). The cover picture shows the preferred conformation of the hexamer of ϵ-amino acid Amc₅ a with a cyclopentane substituent in the backbone investigated using DFT methods in chloroform and water. The Amc₅ a hexamer adopted a stable left-handed conformation with a rise of 4.8 Å per turn both in chloroform and water. However, the hexamer of Ampa (an analogue of Amc₅ a with replacing cyclopentane by pyrrolidine) adopted different conformations in chloroform and in water. Read the full text of their Research Article at 10.1002/open.202100253.

Exploring Helical Folding in Oligomers of Cyclopentane-Based ϵ-Amino Acids: A Computational Study

The conformational preferences of oligopeptides of an ϵ‐amino acid (2‐((1R,3S)‐3‐(aminomethyl)cyclopentyl)acetic acid, Amc₅a) with a cyclopentane substituent in the C^β−C^γ−C^δ sequence of the backbone were investigated using DFT methods in chloroform and water. The most preferred conformation of Amc₅a oligomers (dimer to hexamer) was the H₁₆ helical structure both in chloroform and water. Four residues were found to be sufficient to induce a substantial H₁₆ helix population in solution. The Amc₅a hexamer adopted a stable left‐handed (M)‐2.3₁₆ helical conformation with a rise of 4.8 Å per turn. The hexamer of Ampa (an analogue of Amc₅a with replacing cyclopentane by pyrrolidine) adopted the right‐handed mixed (P)‐2.9_18/16 helical conformation in chloroform and the (M)‐2.4₁₆ helical conformation in water. Therefore, hexamers of ϵ‐amino acid residues exhibited different preferences of helical structures depending on the substituents in peptide backbone and the solvent polarity as well as the chain length.

[The prospects of DNA damage repair variants guiding platinum compounds in the treatment of triple negative breast cancer]

Triple negative breast cancer (TNBC) is prone to recurrence and metastasis, which is the subtype of poorest prognosis. Chemotherapy is the main treatment, although there is lack of effective adjuvant chemotherapy regimens. The unsatisfactory efficacy of chemotherapy has been a bottleneck in improving the outcome of TNBC. Platinum compounds act directly on DNA to kill tumor cells, and they have a stronger killing effect on tumor cells carrying DNA damage repair (DDR) defects, which is an important entry point to improve the efficacy of TNBC. Biomarkers for predicting the efficacy of platinum drugs in TNBC treatment have always been a hot topic. The DDR pathway contains a large number of related genes, and recent studies have shown that deficiencies in the DDR pathway may be associated with the efficacy of platinum drugs, which is expected to be a biomarker for predicting the efficacy of platinum drugs in breast cancer treatment.

Conformational Preferences of Cyclopentane-Based Oligo-δ-peptides in the Gas Phase and in Solution

The conformational preferences of oligomers of δ-amino acid (δAc₅ a) with a cyclopentyl constraint in the C^β -C^γ bond of the backbone were investigated by using DFT methods in the gas phase and in solution. The folded structures with C₁₀ H-bonded pseudocycles were most preferred for dimer and tetramer of δAc₅ a residues both in chloroform and water. However, for the hexameric Ac-(δAc₅ a)₆ -NHMe, the mixed H_16/14 helical structure was found to be most preferred in chloroform (populated at 68 %), whereas the H₁₄ helical structure was the most dominant conformation in water (populated at 60 %). The stability of the former was ascribed to the intrinsic conformational energy, whereas the solvation free energy was crucial to stabilize the latter. Pyrrolidine-substituted analogues of the hexameric Ac-(δAc₅ a)₆ -NHMe, with adjacent amine diads that are almost exactly one turn apart with two nitrogen atoms separated by ca. 5.5 Å, adopted helical structures. They are potential catalysts in nonpolar and polar solvents as they have similar structures to a helical 1 : 2 α:β-heptapeptide that exhibited good catalytic performance in the crossed aldol condensation.

Puckering transition of the proline residue along the pseudorotational path: revisited

Puckering transitions of the proline residue for Ac-Pro-X with trans and cis prolyl peptide bonds were explored along the pseudorotation phase angle using DFT methods in the gas phase and in water.

Conformational preferences of cationic β-peptide in water studied by CCSD(T), MP2, and DFT methods

The conformational preferences of the cationic nylon-3 βNM [(3R,4)-diaminobutanoic acid, dAba] dipeptide in water were explored as the first step to understand the mode of action of polymers of βNM against phylogenetically diverse and intrinsically drug-resistant pathogenic fungi. The CCSD(T), MP2, M06-2X, ωB97X-D, B2PLYP-D3BJ, and DSD-PBEP86-D3BJ levels of theory with various basis sets were assessed for relative energies of the 45 local minima of the cationic Ac-dAba-NHMe located at the SMD M06-2X/6-31+G(d) level of theory in water against the benchmark CCSD(T)/CBS-limit energies in water. The best performance was obtained at the double-hybrid DSD-PBEP86-D3BJ/def2-QZVP level of theory with RMSD = 0.12 kcal/mol in water. The M06-2X/def2-QZVP level of theory predicted reasonably the conformational preference with RMSD = 0.38 kcal/mol in water and may be an alternative level of theory with marginal deviations for the calculation of conformational energies of relatively longer cationic peptides in water. In particular, the H₁₄–helical structures appeared to be the most feasible conformations for the cationic Ac-dAba-NHMe populated at 48–64% by relative free energies in water. The hexamer built from the H₁₄–structure of the cationic Ac-dAba-NHMe adopted a left-handed 3₁₄-helix, which has a slightly narrower radius and a longer rise than the regular 3₁₄-helix of β-peptides. Hence, the 3₁₄-helices of oligomers or polymers of the cationic dAba residues are expected to be the active conformation to exhibit the ability to bridge between charged lipid head groups that might cause a local depression or invagination of the membrane of fungi.

PMFF: Development of a Physics-Based Molecular Force Field for Protein Simulation and Ligand Docking

The physics-based molecular force field (PMFF) was developed by integrating a set of potential energy functions in which each term in an intermolecular potential energy function is derived based on experimental values, such as the dipole moments, lattice energy, proton transfer energy, and X-ray crystal structures. The term "physics-based" is used to emphasize the idea that the experimental observables that are considered to be the most relevant to each term are used for the parameterization rather than parameterizing all observables together against the target value. PMFF uses MM3 intramolecular potential energy terms to describe intramolecular interactions and includes an implicit solvation model specifically developed for the PMFF. We evaluated the PMFF in three ways. We concluded that the PMFF provides reliable information based on the structure in a biological system and interprets the biological phenomena accurately by providing more accurate evidence of the biological phenomena.

Organocatalytic Asymmetric Addition of Aldehyde to Nitroolefin by H-d-Pro-Pro-Glu-NH2: A Mechanistic Study

The mechanism of the asymmetric addition of aldehyde (butanal) to nitroolefin (β-nitrostyrene) catalyzed by H-d-Pro-Pro-Glu-NH₂ (dPPE-NH₂; 1) was explored using density functional theory methods in chloroform. By conformational search, it was confirmed that catalyst 1 and its enamine intermediate adopted a dominant conformation with a βI structure stabilized by a C₁₀ H-bond between the C=O of d-Pro1 and C-terminal NH₂ proton and by an additional H-bond between the side chain and the backbone of Glu3. This βI turn structure was conserved all along the catalytic cycle. Consistently with the kinetic studies, the C-C bond formation between the enamine and electrophile was also confirmed as the rate-determining step. The stereoselectivity results from a re → re prochiral approach of enamine and β-nitrostyrene with a gauche^- orientation of the double bonds. Although it was suggested as the possible formation of dihydrooxazine oxide species, this process was confirmed to be kinetically less accessible than the formation of acyclic nitronate. In particular, our calculated results supported that the carboxylic acid group of Glu3 in 1 played a central role by acting as general acid/base all along the catalytic cycle and orienting the asymmetric C-C bond formation.

Prospect of Thiazole-based γ-Peptide Foldamers in Enamine Catalysis: Exploration of the Nitro-Michael Addition

As three-dimensional folding is prerequisite to biopolymer activity, complex functions may also be achieved through foldamer science. Because of the diversity of sizes, shapes and folding available with synthetic monomers, foldamer frameworks enable a numerous opportunities for designing new generations of catalysts. We herein demonstrate that heterocyclic γ-peptide scaffolds represent a versatile platform for enamine catalysis. One central feature was to determine how the catalytic activity and the transfer of chiral information might be under the control of the conformational behaviours of the oligomer.

Which DFT levels of theory are appropriate in predicting the prolyl cis–trans isomerization in solution?

DFTs were assessed for the conformational preferences of the peptides containing Pro and its derivatives in chloroform and water.

Effects of isosteric substitutions on the conformational preference and cis–trans isomerization of proline-containing peptides

Isosteric substitutions of the peptide CO group by CS and CSe groups increased thetranspopulation and rotational barrier to the prolylcis–transisomerization of proline-containing peptides.

Remote Stereoinductive Intramolecular Nitrile Oxide Cycloaddition: Asymmetric Total Synthesis and Structure Revision of (-)-11β-Hydroxycurvularin

The first total synthesis and structure revision of (-)-11β-hydroxycurvularin (1b), a macrolide possessing a β-hydroxyketone moiety, were accomplished. The β-hydroxyketone moiety in this natural product was introduced by cleavage of the N-O bond in an isoxazoline ring that was formed diastereoselectively in a 1,5-remote stereocontrolled fashion by employing intramolecular nitrile oxide cycloaddition.

Hairpin formation promoted by the heterochiral dinipecotic acid segment: A DFT study

Conformational preferences for the turn and β-hairpin structures of Ala-based peptides [Ac-Ala(n)-(R)-Nip-(S)-Nip-Ala(n)-X (n = 0-2; X = NHMe or NMe2)] containing nipecotic acid (Nip) residues were carried out using the density functional M06-2X and the implicit solvation model SMD in CH2Cl2 and/or water. The turn structure of the (R)-Nip-(S)-Nip segment with a C10 H-bond between two terminal groups was found to be most preferred (populated at 98.9%) in CH2Cl2; this structure is consistent with IR and (1)H NMR results. The stabilities of the β-hairpins containing the (R)-Nip-(S)-Nip segment as a turn motif relative to the extended structures increased with peptide sequence length. The relative strengths of the H-bonds between the carbonyl oxygen and the amide hydrogen appeared to be responsible for stabilizing the turn and β-hairpin structures in CH2Cl2. In addition, the (R)-Nip-(S)-Nip segment exhibited the capability to be incorporated into one of the two β-turn motifs of gramicidin S (GS). The structure of this GS derivative (GS-Nip2 ) was generally similar to the native peptide but was less hydrophobic and it is therefore expected to exhibit lower hemolytic activity; however, further experiments are needed to evaluate its antimicrobial activity. The structure of GS-Nip2 was somewhat more flexible than GS in solvents of higher polarity. Thus, our calculated results regarding the turn and β-hairpin motifs of the (R)-Nip-(S)-Nip segment indicate that this structure might be useful for the design of bioactive macrocyclic peptides containing β-hairpin mimics as well as binding epitopes in protein-protein and protein-nucleic acid recognitions.

Helix foldamers of γ-peptides based on 2-aminocyclopentylacetic acid

Oligo-γ-peptides based on 2-aminocyclopentylacetic acid (γAc₅a) with a cyclopentyl constraint on the C^β–C^γ bond and homochiral (1S,2S) configurations preferentially adopt the right-handed 14-helix foldamers in the gas phase and in solution.

Conformational preferences of β-sheet structures in cyclopropane-containing γ-peptides

Oligo-γ-peptides based on 2-(aminomethyl)cyclopropanecarboxylic acid (γAmc₃) with a cyclopropane constraint on the C^α–C^β bond preferentially formed parallel β-sheets rather than antiparallel β-sheets due to the stronger N–H⋯O H-bonds in the parallel conformation.

IL-23 promotes osteoclastogenesis in osteoblast-osteoclast co-culture system

The aim of this study was to determine the effect of IL-23 on the activity and proliferation of osteoclasts (OC) in co-culture with osteoblasts (OB). OB and OC were individually separated from the skull and femoral bone of a SD rat. OB-OC co-culture with IL-23 added was designed as the experimental group, while the OB-OC co-culture without IL-23 was the control group. In the experimental group, five different concentrations of IL-23 were added, and the cells were then cultured for 24, 48 and 72 h. For each concentration at these three time points, cell proliferation, tartrate-resistant acid phosphatase (TRAP) activity and the lacunae in the bone slices were evaluated, compared with control group at the same time points. Compared to the control group, proliferation and TRAP activity of OC were significantly increased at 24, 48 and 72 h with addition of 0.5 to 10 ng/mL IL-23 (P<0.05). In addition, a dose- and time-dependent correlation between the effect of IL-23 and osteoclastogenesis was noticed though the comparison. Moreover, the area of lacunar resorption in each experimental group was significantly larger than in the control group (P<0.05). In conclusion, IL-23 promotes the proliferation, TRAP activity and bone resorption of OC in OB-OC co-culture.

A randomized phase II study of PEP02 (MM-398), irinotecan or docetaxel as a second-line therapy in patients with locally advanced or metastatic gastric or gastro-oesophageal junction adenocarcinoma

BACKGROUND

PEP02 is a novel highly stable liposomal nanocarrier formulation of irinotecan. This randomized phase II study evaluated the efficacy and safety of single agent PEP02 compared with irinotecan or docetaxel in the second-line treatment of advanced oesophago-gastric (OG) cancer.

PATIENTS AND METHODS

Patients with locally advanced/metastatic disease who had failed one prior chemotherapy regimen were randomly assigned to PEP02 120 mg/m(2), irinotecan 300 mg/m(2) or docetaxel (Taxotere) 75 mg/m(2) every 3 weeks. The primary end point was objective response rate (ORR). Simon's two-stage design was used and the ORR of interest was 20% (α = 0.05, type II error β = 0.10, null hypothesis of ORR was 5%).

RESULTS

Forty-four patients per arm received treatment, and 124 were assessable for response. The ORR statistical threshold for the first stage was reached in all arms. In the intent-to-treat (ITT) population, ORRs were 13.6% (6/44), 6.8% (3/44) and 15.9% (7/44) in the PEP02, irinotecan and docetaxel arms, respectively. The median progression-free survival (PFS) and overall survival were similar between the trial arms. Commonest grade 3-4 adverse event reported was diarrhoea in the PEP02 and irinotecan groups (27.3% versus 18.2%).

CONCLUSION

The ORR associated with PEP02 was comparable with docetaxel and numerically greater than that of irinotecan. PEP02 warrants further evaluation in the advanced gastric cancer setting.

Sorafenib in patients with metastatic gastrointestinal stromal tumors who failed two or more prior tyrosine kinase inhibitors: a phase II study of Korean gastrointestinal stromal tumors study group

PURPOSE

To evaluated the efficacy and safety of sorafenib in patients with advanced gastrointestinal stromal tumors (GIST) who failed to previous standard treatments.

EXPERIMENTAL DESIGN

Thirty-one patients with measurable metastatic GIST who failed both imatinib and sunitinib were accrued. Sorafenib was administered orally at 400 mg twice daily until disease progression or development of intolerance. The primary endpoint was disease control rate (response + stable disease, DCR) at 24 weeks.

RESULTS

Sorafenib was well tolerated, with hand-foot skin reaction, fatigue, hypertension, and abdominal pain being the most frequent adverse events. The relative dose intensity of sorafenib during the first 6 months was >80%. Four patients achieved partial response (response rate 13%, 95% CI 1-25%), and 16 (52%) had stable disease. DCR at 24 weeks was measured as 36% (95% CI 19-52%). Median progression-free and overall survivals were 4.9 and 9.7 months, respectively. Progression-free survival of patients with prior use of nilotinib (P = .0085) and with primary genotypes other than KIT exon 11 mutation (P = .0341) was significantly shorter than that of patients without.

CONCLUSIONS

Sorafenib showed antitumor activity in this population of imatinib and sunitinib pretreated GIST. With sorafenib, about one third of patients can maintain disease control for more than 24 weeks.

Binding free energies of inhibitors to iron porphyrin complex as a model for Cytochrome P450

The binding free energies of the inhibitor-heme model complexes are calculated using the density functional methods and the implicit solvation models in water, where the 16 structurally diverse compounds with a spectrum of IC(50) values from 0.05 (clotrimazole) to 1000 (piroxicam) μM are chosen as inhibitors for Cytochrome P450 3A4 (CYP3A4). CYP3A4 is the most predominant constituent of the human hepatic CYP enzymes that play a role in metabolizing structurally diverse xenobiotics. The observed free energy change for each inhibitory binding, ΔG inh0, is obtained from its IC(50) value. The total binding free energy (ΔG b0) of each inhibitor-heme model complex is calculated by the sum of its relative free energy (ΔG(0) ) in the gas phase and solvation free energy to the water-heme model complex. The UB3LYP/LanL2DZ level of theory provides the correct relative stabilities of the high- and low-spin states for the penta- and hexa-coordinated ferric complexes, respectively. The optimized distances of the inhibitor nitrogen (or water oxygen) and the methyl mercaptide S to the ferric iron of the inhibitor-heme model complexes at the same level of theory are consistent with the values of the corresponding X-ray structures, except for the econazole complex. The correlation coefficient r(2) values of 0.91 and 0.75 are obtained from the ΔG b0-ΔG inh0 and ΔG(0) -ΔG inh0 plots, respectively, at the UM06/LanL2DZ:CPCM_UB3LYP/LanL2DZ//UB3LYP/LanL2DZ level of theory in water. This indicates that the total binding free energies calculated for the inhibitor-heme model complexes can be a good descriptor in interpreting the inhibitor binding to CYP3A4 and the relative free energies in the gas phase are mainly responsible for the total binding free energies in water, although the desolvation can be a factor to affect the binding affinity of the inhibitors to CYP3A4. From the theozyme analysis of the X-ray structures for ketoconazole- and metyrapone-CYP3A4 complexes, the interaction free energy of the neighboring residues with each inhibitor in the active site is calculated to be about -3 kcal mol(-1) in water, whose the interaction energy and the desolvation free energy change are about -5 and 2 kcal mol(-1) , respectively.