Status of incremental costs of first-line treatment recommended in Japanese clinical guidelines for metastatic breast cancer patients.

BACKGROUND: The increasing incidence and prevalence of breast cancer alongside diagnostic and treatment technology advances have produced a debate about the financial burden cancer places on the healthcare system and concerns about access. METHODS: This study was conducted at 51 hospitals belonging to the Breast Cancer Study Group of the Japan Clinical Oncology Group using a web-based survey. The survey period conducted from July 2021 to June 2022. The study population included patients with metastatic breast cancer who received the related treatment as their first-line therapy. The proportion of patients who selected that regimen as their first-line treatment was tabulated. The total cost increase for each current standard therapy in comparison to conventional treatments was calculated. RESULTS: A total of 702 patients (pts) were surveyed. Of those enrolled, 342 (48.7%) received high-cost treatment [estimated monthly drug costs exceeding ~500 000 Japanese Yen (JPY)]. Of these, 16 pts (4.7%) were receiving very high-cost treatment, amounting to more than 1 000 000 JPY per month. Fifty three (15.5%) of the patients who received high-cost treatment were 75 years of age or older. Of these, 1 pt (0.3%) were receiving very high-cost treatment. Analyses of incremental costs by current drugs showed that abemaciclib was costly with total additional cost of 6 365 670 JPY per patient. The total additional cost of the regimen per patient that included palbociclib was the second highest at 4011248 JPY, followed by atezolizumab at 3209033 JPY. CONCLUSIONS: The findings indicate that evaluating the financial implications of high-cost treatments requires considering not only drug prices but also analysis of total cost increase.

A case of carcinoid syndrome probably exacerbated by hemodialysis in which prochlorperazine maleate was effective.

Carcinoid syndrome is caused by the release of serotonin and other substances, which commonly occurs due to liver metastasis of neuroendocrine tumors. It rarely occurs due to liver metastasis of neuroendocrine carcinoma. We report the case of a patient with liver metastasis of neuroendocrine carcinoma who suffered from acute abdominal pain and diarrhea triggered by hemodialysis. Various differential diagnoses were considered, but we concluded these symptoms to be probably caused by exacerbation of carcinoid syndrome, as the serum 5HIAA level was markedly elevated, and a drug with anti-serotonin activity was effective. Prochlorperazine maleate, which has anti-serotonin activity, was effective for these symptoms, and the patient was able to continue maintenance hemodialysis, which contributed to his quality of life and prognosis. We speculated the mechanism of carcinoid exacerbation was that substances such as serotonin had entered the systemic circulation via the increased extrahepatic shunt of the portal venous blood flow, entering the inferior vena cava and that this condition had been triggered by hemodialysis via the same mechanism as portal systemic encephalopathy.

Ganglioside GD2 Expression Is Associated With Unfavorable Prognosis in Early Triple-negative Breast Cancer.

BACKGROUND/AIM: Gangliosides (acidic glycosphingolipids) have crucial regulatory roles in normal physiological processes, as well as in pathological conditions, including tumor onset and progression. GD2 is highly expressed in triple-negative breast cancer (TNBC), particularly in cancer stem cells. However, little is known on the clinical impact of GD2 expression on the prognosis of TNBC. Consequently, we aimed to investigate the association between GD2 expression in TNBC and the prognosis of TNBC. PATIENTS AND METHODS: We assessed GD2 expression in 76 patients with primary TNBC who had undergone surgery at our Institute between 2012 and 2015 using immunohistochemical analysis with a tissue microarray technique. We investigated the relationship between GD2 expression and clinicopathological factors in TNBC, recurrence-free survival (RFS), and overall survival (OS). RESULTS: Increased GD2 expression was observed in 45% of TNBC patients. There was no significant association between GD2 expression and clinicopathological factors in TNBC. The 5-year RFS rate among patients with GD2-positive TNBCs was significantly worse than that among patients with GD2-negative TNBCs (75.4% and 94.9%; HR=4.931; 95%CI=1.024-23.752; p=0.027). The OS in patients with GD2-positive TNBCs tended to be inferior to that of patients with GD2-negative TNBCs (HR=5.357; 95%CI=0.599-47.939; p=0.092). Interestingly, in patients with GD2-positive TNBCs, a higher grade of tumor-infiltrating lymphocytes (TILs) displayed a significantly better impact on OS (TILs-high vs. TILs-low; p=0.04). Both univariate and multivariate analyses showed that GD2 expression negatively affected RFS (p=0.027, p=0.021, respectively). CONCLUSION: GD2 expression is an independent unfavorable prognostic factor for TNBC.

Preferences Regarding Breast Surgery Omission Among Patients With Breast Cancer Who Receive Neoadjuvant Chemotherapy.

BACKGROUND/AIM: Currently, several ongoing prospective studies are investigating the safety of breast surgery omission in patients with breast cancer who are exceptional responders to neoadjuvant chemotherapy. However, there is little information about the preferences of these patients regarding omission of breast surgery. PATIENTS AND METHODS: We conducted a questionnaire survey to assess preferences regarding omission of breast surgery among patients with breast cancer who had human epidermal growth factor receptor 2-positive or estrogen receptor-negative tumors and good clinical response after neoadjuvant chemotherapy. Patients' estimation of the risk of ipsilateral breast tumor recurrence (IBTR) after definitive surgery or breast surgery omission was also assessed. RESULTS: Of 93 patients, only 22 (23.7%) said they would omit breast surgery. Under the scenario of omitting breast surgery, the 5-year IBTR rate estimated by patients who said they would omit breast surgery was significantly lower (median, 10%) than the rate estimated by patients who preferred undergoing definitive surgery (median, 30%) (p=0.017). CONCLUSION: The proportion of our surveyed patients who were willing to omit breast surgery was low. Patients who said they preferred to omit breast surgery overestimated the 5-year IBTR risk.

[Interstitial Lung Disease after OK-432 Pleurodesis for Malignant Pleural Effusion in Breast Cancer-A Case Report].

The patient was a 42-year-old woman. After 4 courses of capecitabine therapy for right chest wall recurrence of breast cancer, ER(+, 10-15%), PgR(-), HER2(-), she underwent pleurodesis using OK-432 for increased right pleural effusion. On the 12th day after pleurodesis diffuse infiltrative shadows in the right lung, and frosted shadows in both lungs, were observed, and she was diagnosed with drug-induced lung injury. About 3 weeks after administration of prednisolone 1 mg/ kg a tendency for improvement in lung injury was observed, but the patient died of breast cancer progression. Drug- induced lung injury by pleurodesis carries the risk of delaying resumption of chemotherapy. We report this case with a review of the literature.

Aortic dissection diagnosed with the aortic dissection detection risk score of 2 without D-dimer elevation.

Acute aortic dissection can be fatal if overlooked, and the absence of D-dimer elevation can be used to exclude acute aortic dissection. However, we report a case of acute aortic dissection without D-dimer elevation. A man in his 70s presented to the emergency department with lumbar back pain. D-dimer was <1.0 µg/mL; however, acute aortic dissection was strongly suspected because of the sudden onset of lumbar back pain with a shifting location. Because of a difference in systolic blood pressure in both upper extremities, we performed a thorough examination using contrast-enhanced CT, leading to a diagnosis of acute aortic dissection. The patient was immediately referred to cardiovascular surgery and treated conservatively with antihypertensive management. The aortic dissection detection risk score (ADD-RS) classified the patient as high risk. This suggests the importance of using the D-dimer with the ADD-RS rather than solely relying on the D-dimer results to diagnose acute aortic dissection.

MTR4 adaptor PICT1 functions in two distinct steps during pre-rRNA processing.

Ribosome biogenesis proceeds with the successive cleavage and trimming of the large 47S rRNA precursor, where the RNA exosome plays major roles in concert with the Ski2-like RNA helicase, MTR4. The recent finding of a consensus amino acid sequence, the arch-interacting motif (AIM), for binding to the arch domain in MTR4 suggests that recruitment of the RNA processing machinery to the maturing pre-rRNA at appropriate places and timings is mediated by several adaptor proteins possessing the AIM sequence. In yeast Saccharomyces cerevisiae, Nop53 plays such a role in the maturation of the 3'-end of 5.8S rRNA. Here, we investigated the functions of PICT1 (also known as GLTSCR2 or NOP53), a mammalian ortholog of Nop53, during ribosome biogenesis in human cells. PICT1 interacted with MTR4 and exosome in an AIM-dependent manner. Overexpression of PICT1 mutants defecting AIM sequence and siRNA-mediated depletion of PICT1 showed that PICT1 is involved in two distinct pre-rRNA processing steps during the generation of 60S ribosomes; first step is the early cleavage of 32S intermediate RNA, while the second step is the late maturation of 12S precursor into 5.8S rRNA. The recruitment of MTR4 and RNA exosome via the AIM sequence was required only during the late processing step. Although, the depletion of MTR4 and PICT1 induced stabilization of the tumor suppressor p53 protein in cancer cell lines, the depletion of the exosome catalytic subunits, RRP6 and DIS3, did not exert such an effect. These results suggest that recruitment of the RNA processing machinery to the 3'-end of pre-5.8S rRNA may be involved in the induction of the nucleolar stress response, but the pre-rRNA processing capabilities themselves were not involved in this process.

Long-range axonal projections of transplanted mouse embryonic stem cell-derived hypothalamic neurons into adult mouse brain.

The hypothalamus is comprised of heterogenous cell populations and includes highly complex neural circuits that regulate the autonomic nerve system. Its dysfunction therefore results in severe endocrine disorders. Although recent experiments have been conducted for in vitro organogenesis of hypothalamic neurons from embryonic stem (ES) or induced pluripotent stem (iPS) cells, whether these stem cell-derived hypothalamic neurons can be useful for regenerative medicine remains unclear. We therefore performed orthotopic transplantation of mouse ES cell (mESC)-derived hypothalamic neurons into adult mouse brains. We generated electrophysiologically functional hypothalamic neurons from mESCs and transplanted them into the supraoptic nucleus of mice. Grafts extended their axons along hypothalamic nerve bundles in host brain, and some of them even projected into the posterior pituitary (PPit), which consists of distal axons of the magnocellular neurons located in hypothalamic supraoptic and paraventricular nuclei. The axonal projections to the PPit were not observed when the mESC-derived hypothalamic neurons were ectopically transplanted into the substantia nigra reticular part. These findings suggest that our stem cell-based orthotopic transplantation approach might contribute to the establishment of regenerative medicine for hypothalamic and pituitary disorders.

Efficacy and impact of SARS-CoV-2 vaccination on cancer treatment for breast cancer patients: a multi-center prospective observational study.

PURPOSE: Vaccination is an essential strategy to prevent infection in the SARS-CoV-2 pandemic. However, there are concerns about vaccine efficacy and the impact of vaccination on cancer treatment. Additionally, the emergence of novel variants may affect vaccination efficacy. This multi-center, prospective, observational study investigated the efficacy and impact of vaccination against SARS-CoV-2 variants on treatment among breast cancer patients in Japan. METHODS: Patients with breast cancer scheduled to be vaccinated with the SARS-CoV-2 vaccine from May to November 2021 were prospectively enrolled (UMIN000045527). They were stratified into five groups according to their cancer treatment: no treatment, hormone therapy, anti-human epidermal growth factor receptor (HER)2 therapy, chemotherapy, and cyclin-dependent kinase 4/6 (CDK4/6) inhibitor. Serum samples for assessing serological responses were collected before the first vaccination and after the second vaccination. RESULTS: Eighty-five breast cancer patients were included. The overall seroconversion rate after second vaccination was 95.3% and the lowest seroconversion rate was 81.8% in the patients under chemotherapy. The overall positivity rate of neutralizing antibodies against the wild-type, α, Δ, κ, and omicron variants were 90.2%, 81.7%, 96.3%, 84.1%, and 8.5%, respectively. Among the patients under chemotherapy or CDK4/6 inhibitors, various degrees of decreased neutralizing antibody titers against SARS-CoV-2 variants were observed. Withdrawal or reduction of systemic therapy because of vaccination was observed in only one patient. CONCLUSION: Our data support SARS-CoV-2 vaccination for breast cancer patients. However, a reduction in neutralizing antibody titers was suggested during chemotherapy and CDK4/6 inhibitors, raising concerns about the impact on long-term infection prevention.

EpCAM Is a Surface Marker for Enriching Anterior Pituitary Cells From Human Hypothalamic-Pituitary Organoids.

Human stem cell-derived organoid culture enables the in vitro analysis of the cellular function in three-dimensional aggregates mimicking native organs, and also provides a valuable source of specific cell types in the human body. We previously established organoid models of the hypothalamic-pituitary (HP) complex using human pluripotent stem cells. Although the models are suitable for investigating developmental and functional HP interactions, we consider that isolated pituitary cells are also useful for basic and translational research on the pituitary gland, such as stem cell biology and regenerative medicine. To develop a method for the purification of pituitary cells in HP organoids, we performed surface marker profiling of organoid cells derived from human induced pluripotent stem cells (iPSCs). Screening of 332 human cell surface markers and a subsequent immunohistochemical analysis identified epithelial cell adhesion molecule (EpCAM) as a surface marker of anterior pituitary cells, as well as their ectodermal precursors. EpCAM was not expressed on hypothalamic lineages; thus, anterior pituitary cells were successfully enriched by magnetic separation of EpCAM+ cells from iPSC-derived HP organoids. The enriched pituitary population contained functional corticotrophs and their progenitors; the former responded normally to a corticotropin-releasing hormone stimulus. Our findings would extend the applicability of organoid culture as a novel source of human anterior pituitary cells, including stem/progenitor cells and their endocrine descendants.

Possible Metastatic Stage-Dependent ILC2 Activation Induces Differential Functions of MDSCs through IL-13/IL-13Rα1 Signaling during the Progression of Breast Cancer Lung Metastasis.

Breast cancer is the most common cancer in women worldwide, and lung metastasis is one of the most frequent distant metastases. When breast cancer metastasizes to the lung, group 2 innate lymphoid cells (ILC2s) are thought to promote tumor growth via the activation of myeloid-derived suppressor cells (MDSCs), which are known to negatively regulate anticancer immune responses. However, it remains to be elucidated exactly how this ILC2-MDSC interaction is involved in tumor growth during metastases formation. Using a 4T1/LM4 breast cancer mouse model, we found that ILC2s were activated in both the micro- and macrometastatic regions, suggesting sustained activation throughout the metastatic cascades via IL-33/ST2 signaling. Consistent with IL-13 secretion from activated ILC2s, the frequencies of polymorphonuclear (PMN)- and monocytic (M)-MDSCs were also significantly elevated during the progression from micro- to macrometastatic cancer. However, the effects of ILC2-induced MDSC functionality on the microenvironment differed in a metastatic-stage-specific manner. Our findings indicate that ILC2s may induce the immunosuppressive functions of MDSCs during the later stages of metastasis. Concomitantly, ILC2 may instigate extracellular matrix remodeling by PMN-MDSC activation during the early stages of metastasis. These metastatic-stage-specific changes may contribute to metastatic tumor growth in the microenvironment of breast cancer lung metastasis.

Nickel-catalyzed skeletal transformation of tropone derivatives via C-C bond activation: catalyst-controlled access to diverse ring systems.

We report herein on nickel-catalyzed carbon-carbon bond cleavage reactions of 2,4,6-cycloheptatrien-1-one (tropone) derivatives. When a Ni/N-heterocyclic carbene catalyst is used, decarbonylation proceeds with the formation of a benzene ring, while the use of bidentate ligands in conjunction with an alcohol additive results in a two-carbon ring contraction with the generation of cyclopentadiene derivatives. The latter reaction involves a nickel-ketene complex as an intermediate, which was characterized by X-ray crystallography. The choice of an appropriate ligand allows for selective synthesis of four different products via the cleavage of a seven-membered carbocyclic skeleton. Reaction mechanisms and ligand-controlled selectivity for both types of ring contraction reactions were also investigated computationally.

SMARCA2/BRM-Deficient Undifferentiated/Rhabdoid Carcinoma of Unknown Primary Site.

Undifferentiated neoplasms of unknown primary sites are rare. It is difficult to identify their characteristics and determine the appropriate chemotherapy regimen to be used. Undifferentiated/rhabdoid carcinoma is reportedly associated with loss of SWI/SNF chromatin remodeling complexes, such as observed in SMARCA4-deficient tumors. However, little is known about SMARCA2/BRM-deficient tumors. A 48-year-old man presented with low back pain. Computed tomography (CT) revealed intraperitoneal lymph nodes and multiple bone metastases that invaded the thoracic and lumbar spinal canals. The primary tumor was not identified despite the standard diagnostic methods being used. CT-guided needle biopsy of right iliac bone metastasis showed that the tumor had an undifferentiated/rhabdoid morphology. Immunostaining revealed that the tumor was SMARCA2/BRM-deficient despite both SMARCB1/INI1 and SMARCA4/BRG being retained. We found no genomic alterations during domestic next-generation sequencing panel profiling, which can identify 114 genes. Thus, he was diagnosed with SMARCA2/BRM-deficient undifferentiated/rhabdoid carcinoma of an unknown primary site with multiple bone metastases and intraperitoneal lymph node metastasis. We administered radiotherapy to the thoracic and lumbar spine to improve cord compression, and carboplatin (CBDCA) and paclitaxel regimen was chosen as first-line chemotherapy, but this was discontinued due to an anaphylactic shock. We then selected the CBDCA and gemcitabine regimens; however, the patient did not continuously receive the regimen due to myelosuppression. Radiation therapy effectively relieves pain and cord compression. To our knowledge, this is the first reported case of SMARCA2/BRM-deficient undifferentiated/rhabdoid carcinoma of an unknown primary site. Further studies are needed to improve SWI/SNF-deficient tumor identification methods.

Characterization of Hypothalamic MCH Neuron Development in a 3D Differentiation System of Mouse Embryonic Stem Cells.

Hypothalamic melanin-concentrating hormone (MCH) neurons are important regulators of multiple physiological processes, such as sleep, feeding, and memory. Despite the increasing interest in their neuronal functions, the molecular mechanism underlying MCH neuron development remains poorly understood. We report that a three-dimensional culture of mouse embryonic stem cells (mESCs) can generate hypothalamic-like tissues containing MCH-positive neurons, which reproduce morphologic maturation, neuronal connectivity, and neuropeptide/neurotransmitter phenotype of native MCH neurons. Using this in vitro system, we demonstrate that Hedgehog (Hh) signaling serves to produce major neurochemical subtypes of MCH neurons characterized by the presence or absence of cocaine- and amphetamine-regulated transcript (CART). Without exogenous Hh signals, mESCs initially differentiated into dorsal hypothalamic/prethalamic progenitors and finally into MCH+CART+ neurons through a specific intermediate progenitor state. Conversely, activation of the Hh pathway specified ventral hypothalamic progenitors that generate both MCH+CART- and MCH+CART+ neurons. These results suggest that in vivo MCH neurons may originate from multiple cell lineages that arise through early dorsoventral patterning of the hypothalamus. Additionally, we found that Hh signaling supports the differentiation of mESCs into orexin/hypocretin neurons, a well-defined cell group intermingled with MCH neurons in the lateral hypothalamic area (LHA). The present study highlights and improves the utility of mESC culture in the analysis of the developmental programs of specific hypothalamic cell types.

Expression and purification of DYRK1A kinase domain in complex with its folding intermediate-selective inhibitor FINDY.

The kinase DYRK1A phosphorylates substrate proteins that are involved in the progression of many diseases. DYRK1A also phosphorylates its own residues on key elements intramolecularly to activate and stabilize itself during the folding process. Once the folding process of DYRK1A has completed, it can no longer catalyzes the intramolecular reaction, suggesting that a transitional intermediate state that catalyzes the autophosphorylation exists. In the previous study, we identified a small molecule, designated as FINDY, that selectively inhibits the folding intermediate of DYRK1A. Although evidence has suggested that FINDY targets the ATP-binding pocket of DYRK1A, it remains elusive as to whether the DYRK1A kinase domain could be purified as a complex with FINDY. In this study, we successfully expressed and purified the kinase domain of DYRK1A in complex with FINDY. The DYRK1A kinase domain was expressed as a fusion protein with a hexahistidine tag and ZZ-domain (His-ZZ-DYRK1A) at 6 °C by using a cold shock induction system in Escherichia coli cells. The cells were incubated with FINDY. The cell pellets were gently extracted on ice and subjected to immobilized-metal affinity chromatography. The amount of FINDY in the elution fraction was measured by UV absorbance specific for FINDY. The eluate contained FINDY with the ratio of FINDY to DYRK1A protein being 0.15 in quadruplicate experiments. Thus, this study demonstrates the direct interaction between the DYRK1A kinase domain and FINDY, paving the way for structural determination of the complex.

Atezolizumab-Induced Sarcoidosis-Like Reaction in a Patient with Metastatic Breast Cancer.

Tumor-related sarcoidosis-like reactions (SLR) have been reported with the use of immune checkpoint inhibitors (ICIs). We report a case of 50-year-old woman who observed an enlarged lymph node in the right hilar region and the appearance of a subcutaneous mass in the extremities during chemotherapy with atezolizumab plus nab-paclitaxel for metastatic triple-negative breast cancer (TNBC). Skin biopsy revealed the formation of epithelioid granulation species with the Langhans giant cell. After discontinuing atezolizumab in the treatment procedure, the hilar lymph nodes and the subcutaneous mass were reduced. A pathological examination was effective in differentiating tumor exacerbation from SLR. Owing to limited information on ICI-related SLR in breast cancer, future studies are recommended to properly manage immune-related adverse effects during cancer treatment.

A Case of Metaplastic Squamous Cell Carcinoma of the Breast that Showed a Pathological Complete Response After Neoadjuvant Chemotherapy with Weekly Paclitaxel.

BACKGROUND Primary squamous cell carcinoma of the breast is a rare type of metaplastic breast carcinoma, characterized by resistance to conventional chemotherapy agents. We report a case of metaplastic squamous cell carcinoma of the breast in which a pathological complete response was achieved after neoadjuvant chemotherapy with weekly paclitaxel and in which the patient remained disease free for 15 years and 7 months. CASE REPORT A 40-year-old woman had a palpable 5-cm-diameter tumor in the right breast that was diagnosed as metaplastic squamous cell carcinoma of the breast based on core needle biopsy. The patient was initially treated with an adjuvant chemotherapy (AC) regimen consisting of doxorubicin (60 mg/m²) and cyclophosphamide (600 mg/m²) as neoadjuvant chemotherapy. Because the tumor grew rapidly and the skin redness increased after 1 cycle of the AC regimen, 12 cycles of weekly paclitaxel 80 mg/m² were subsequently administered. The tumor responded dramatically to paclitaxel. The patient underwent mastectomy with level II axillary lymph node dissection. No residual tumor cells were found, which indicated pathological complete response. The patient is currently disease free at 15 years and 7 months after the operation. CONCLUSIONS To our knowledge, there are no previous reports of metaplastic squamous cell carcinoma of the breast in which pathological complete response was achieved by treatment with neoadjuvant chemotherapy with weekly paclitaxel (80 mg/m²).

Developmentally interdependent stretcher-compressor relationship between the embryonic brain and the surrounding scalp in the preosteogenic head.

BACKGROUND: How developing brains mechanically interact with the surrounding embryonic scalp layers (ie, epidermal and mesenchymal) in the preosteogenic head remains unknown. Between embryonic day (E) 11 and E13 in mice, before ossification starts in the skull vault, the angle between the pons and the medulla decreases, raising the possibility that when the elastic scalp is directly pushed outward by the growing brain and thus stretched, it recoils inward in response, thereby confining and folding the brain. RESULTS: Stress-release tests showed that the E11-13 scalp recoiled and that the in vivo prestretch prerequisite for this recoil was physically dependent on the brain (pressurization at 77-93 Pa) and on actomyosin and elastin within the scalp. In scalp-removed heads, brainstem folding was reduced, and the spreading of ink from the lateral ventricle to the spinal cord that occurred in scalp-intact embryos (with >5 µL injection) was lost, suggesting roles of the embryonic scalp in brain morphogenesis and cerebrospinal fluid homeostasis. Under nonstretched conditions, scalp cell proliferation declined, while the restretching of the shrunken scalp rescued scalp cell proliferation. CONCLUSIONS: In the embryonic mouse head before ossification, a stretcher-compressor relationship elastically develops between the brain and the scalp, underlying their mechanically interdependent development.

Structure-activity relationship for the folding intermediate-selective inhibition of DYRK1A.

DYRK1A phosphorylates proteins involved in neurological disorders in an intermolecular manner. Meanwhile, during the protein folding process of DYRK1A, a transitional folding intermediate catalyzes the intramolecular autophosphorylation required for the "one-off" inceptive activation and stabilization. In our previous study, a small molecule termed FINDY (1) was identified, which inhibits the folding intermediate-catalyzed intramolecular autophosphorylation of DYRK1A but not the folded state-catalyzed intermolecular phosphorylation. However, the structural features of FINDY (1) responsible for this intermediate-selective inhibition remain elusive. In this study, structural derivatives of FINDY (1) were designed and synthesized according to its predicted binding mode in the ATP pocket of DYRK1A. Quantitative structure-activity relationship (QSAR) of the derivatives revealed that the selectivity against the folding intermediate is determined by steric hindrance between the bulky hydrophobic moiety of the derivatives and the entrance to the pocket. In addition, a potent derivative 3 was identified, which inhibited the folding intermediate more strongly than FINDY (1); it was designated as dp-FINDY. Although dp-FINDY (3) did not inhibit the folded state, as well as FINDY (1), it inhibited the intramolecular autophosphorylation of DYRK1A in an in vitro cell-free protein synthesis assay. Furthermore, dp-FINDY (3) destabilized endogenous DYRK1A in HEK293 cells. This study provides structural insights into the folding intermediate-selective inhibition of DYRK1A and expands the chemical options for the design of a kinase inhibitor.