Use of budget savings from patent expiration of cancer drugs to improve affordability and accessibility.

BACKGROUND: The introduction of generics after the loss of patent exclusivity plays a major role in budget savings by significantly decreasing drug prices. The aims of this study were to estimate the budget savings from off-patent cancer drugs in 2020-2024 and to inform decision makers on how these savings could be used to improve the affordability of innovative cancer treatments in South Korea. METHODS: A model was developed to calculate budget savings from off-patent cancer drug use in Korea over 5 years (2020-2024). Cancer drugs with one or more valid patents that expire between 2020 and 2024 in Korea were selected. Key input parameters in the model included market share of generics, market growth, and prices of originators and generics. To reflect market dynamics after patent expiration, the trends of the off-patent market were estimated using historical sales volume data of IQVIA from 2012 to 2018. The study assumed that the prices of off-patent drugs decreased according to the price regulations set by the Korean government and that the off-patent market sales volume did not grow. Sensitivity analyses were performed to investigate the uncertainty in model input parameters. RESULTS: A total of 24 cancer drugs which met selection criteria were identified. In the base case analysis, patent expiration of cancer drugs between 2020 and 2024 could lead to a spending reduction of ₩234,429 million ($203 million), which was 20% of the cancer drug expenditure in the 5-year period. The savings ranged from ₩157,633 million ($136 million) to ₩434,523 million ($376 million) depending on the scenarios in sensitivity analyses. CONCLUSIONS: The findings indicate that patent loss of cancer drugs could lead to a 20% reduction in spending on cancer drugs over the next 5 years in South Korea. The savings could be used to improve the affordability of innovative, advanced cancer drugs for 94,000 cancer patients by reallocating the budget savings from patent expiration.

Excess electron transfer dynamics in DNA hairpins conjugated with N,N-dimethylaminopyrene as a photosensitizing electron donor.

Excess electron transfer dynamics in DNA hairpins was investigated by femtosecond laser flash photolysis of a donor-DNA-acceptor system using N,N-dimethylaminopyrene and diphenylacetylene as an electron donor and acceptor, respectively. It was revealed that the excess electron hopping rate between T's is faster than that of the hole.

Excess-electron injection and transfer in terthiophene-modified DNA: terthiophene as a photosensitizing electron donor for thymine, cytosine, and adenine.

Excess-electron transfer (EET) in DNA has attracted wide attention owing to its close relation to DNA repair and nanowires. To clarify the dynamics of EET in DNA, a photosensitizing electron donor that can donate an excess electron to a variety of DNA sequences has to be developed. Herein, a terthiophene (3T) derivative was used as the photosensitizing electron donor. From the dyad systems in which 3T was connected to a single nucleobase, it was revealed that (1) 3T* donates an excess electron efficiently to thymine, cytosine, and adenine, despite adenine being a well-known hole conductor. The free-energy dependence of the electron-transfer rate was explained on the basis of the Marcus theory. From the DNA hairpins, it became clear that (1) 3T* can donate an excess electron not only to the adjacent nucleobase but also to the neighbor one nucleobase further along and so on. From the charge-injection rate, the possibilities of smaller ß value and/or charge delocalization were discussed. In addition, EET through consecutive cytosine nucleobases was suggested.

Direct measurement of the dynamics of excess electron transfer through consecutive thymine sequence in DNA.

Charge transfer in DNA is an essential process in biological systems because of its close relation to DNA damage and repair. DNA is also an important material used in nanotechnology for wiring and constructing various nanomaterials. Although hole transfer in DNA has been investigated by various researchers and the dynamic properties of this process have been well established, the dynamics of a negative charge, that is, excess electron, in DNA have not been revealed until now. In the present paper, we directly measured the rate of excess electron transfer (EET) through a consecutive thymine (T) sequence in nicked-dumbbell DNAs conjugated with a tetrathiophene derivative (4T) as an electron donor and diphenylacetylene (DPA) as an electron acceptor at both ends. The selective excitation of 4T by a femtosecond laser pulse caused the excess electron injection into DNA, and led to EET in DNA by a consecutive T-hopping mechanism, which eventually formed the DPA radical anion (DPA(•-)). The rate constant for the process of EET through consecutive T was determined to be (4.4 ± 0.3) × 10(10) s(-1) from an analysis of the kinetic traces of the ΔO.D. during the laser flash photolysis. It should be emphasized that the EET rate constant for T-hopping is faster than the rate constants for oxidative hole transfers in DNA (10(4) to 10(10) s(-1) for A- and G-hopping).

Intramolecular exciplex and intermolecular excimer formation of 1,8-naphthalimide-linker-phenothiazine dyads.

Steady-state fluorescence spectra were measured for 1,8-naphthahlimide-linker-phenothiazine dyads (NI-L-PTZ, where L = octamethylenyl ((CH2)8) and 3,6,9-trioxaundecyl ((CH2CH2O)3C2H4)), NI-C8-PTZ and NI-O-PTZ, as well as the NI derivatives substituted on the nitrogen atom with various linker groups without PTZ as the reference NI molecule in n-hexane. Normal fluorescence peaks were observed at 367-369 nm in all NI molecules together with a broader emission around 470 nm, which is assigned to the excimer emission between the NI in the singlet excited state (1NI*) and the NI moiety of another NI molecule (1[NI/NI]*). In addition, a broad peak around 600 nm was observed only for NI-L-PTZ, which is assigned to an intramolecular exciplex emission between donor (PTZ) and acceptor (NI) moieties in the excited singlet state, 1[NI-L-NI]*. The formation of an intramolecular exciplex corresponds to the existence of a conformer with a weak face-to-face interaction between the NI and PTZ moieties in the excited state because of the long and flexible linkers. The excited-state dynamics of the NI molecules in n-hexane were established by means of time-resolved fluorescence spectroscopy.