RETWT (IC50 = 14.0 nM); RETV804M (IC50 = 24.1 nM); RETG810R (IC50 = 530.7 nM)

Selpercatinib (LOXO-292) is a orally bioavailable, potent and selective RET kinase inhibitor.
Selpercatinib inhibited cell growth of Ba/F3 RET Δ898-901 and RET C634R with a similar half maximal inhibitory concentration (IC50) of approximately 3 nM. [3]
Selpercatinib was able to inhibit cell proliferation of both Ba/F3 RET Δ898-901 and Ba/F3 RET C634R cells very efficiently, with an IC50 dose of around 3 nM for both cell lines. Thus, RET Δ898-901 and RET C634R phosphorylation were equally inhibited by selpercatinib in these cells (Fig 4B). Vandetanib was around five-fold less effective at inhibiting cell growth promoted by RET Δ898-901 mutant (IC50, 564 nM) compared with RET C634R one (IC50, 91 nM; Fig 4C). [3]

Selpercatinib (LOXO-292; 10 mg/kg; i.g.; for 0-2 h) demonstrates favorable pharmacokinetics following oral gavage in FVB/NRj mice[1].

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The patient showed primary resistance to vandetanib and secondary resistance to selpercatinib after 12 months. Comprehensive next-generation sequencing of a progressing lesion during selpercatinib showed no additional RET mutation but an acquired complete genetic loss of CDKN2A, CDKN2B, and MTAP genes. Subsequent treatment with cabozantinib and 5-FU-dacarbazine had poor efficacy. [3]

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In total, 212 patients underwent randomization in the intention-to-treat-pembrolizumab population. At the time of the preplanned interim efficacy analysis, median progression-free survival was 24.8 months (95% confidence interval [CI], 16.9 to not estimable) with selpercatinib and 11.2 months (95% CI, 8.8 to 16.8) with control treatment (hazard ratio for progression or death, 0.46; 95% CI, 0.31 to 0.70; P<0.001). The percentage of patients with an objective response was 84% (95% CI, 76 to 90) with selpercatinib and 65% (95% CI, 54 to 75) with control treatment. The cause-specific hazard ratio for the time to progression affecting the central nervous system was 0.28 (95% CI, 0.12 to 0.68). Efficacy results in the overall intention-to-treat population (261 patients) were similar to those in the intention-to-treat-pembrolizumab population. The adverse events that occurred with selpercatinib and control treatment were consistent with those previously reported. Conclusions: Treatment with selpercatinib led to significantly longer progression-free survival than platinum-based chemotherapy with or without pembrolizumab among patients with advanced RET fusion-positive NSCLC [4].

LOXO292 (1 µM) was added to the cells two hours prior to ALKAL2 or GDNF stimulation.

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Growth Curves and Cell Viability Assay [3]
RET C634R– and RET Δ898-901–transformed NIH3T3 cells were seeded in 6-well plates (10,000/well). NIH3T3 transfectants were grown in 2.5% CS. Cells were counted in triplicate every 2 days. RET C634R– and RET Δ898-901–transformed Ba/F3 were seeded in 6-well plates (300,000/well). The day after plating, cells were counted, and various concentrations of drug or vehicle were added to the medium. Cells were counted in triplicate daily for 4 consecutive days and the number of cells relative to the last day of the experiment was used to calculate growth inhibition. Half maximal inhibitory concentration (IC50) doses for cell growth were calculated through a curve fitting analysis from last day of growth curves using the Prism software [3].

Female nu/nu BALB/c mice
3 mg/kg
o.g.

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Female BALB/c nu/nu mice were used. All manipulations were performed while the animals were under isoflurane gas anesthesia. No mouse showed signs of wasting or other signs of toxicity. Four mice were inoculated subcutaneously into both flanks with 2 × 105 RET C634R– or RET Δ898-901–transformed NIH3T3 (two mice for each cell line). After 14 days, tumors were measured by calypter. Mice were euthanized by cervical dislocation; tumors were excised and snap-frozen in liquid nitrogen. Frozen tumors were then homogenized in lysis buffer by using the Mixer Mill MM300. Samples were clarified twice by centrifugation at 10,000×g. Protein phosphorylation was assayed according to standard Western blot procedures. [3]

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Patients were randomly assigned to receive either selpercatinib (160 mg twice daily) in continuous 21-day cycles or pemetrexed (500 mg per square meter of body-surface area) with vitamin supplementation along with the investigator’s choice of platinum therapy (carboplatin [area under the concentration–time curve, 5; maximum dose, 750 mg] or cisplatin [75 mg per square meter]) with or without pembrolizumab (200 mg) every 21 days. Patients were stratified according to geographic region (East Asia vs. elsewhere), status with respect to brain metastases at baseline (absent or unknown vs. present), and whether the investigator had intended (before randomization) to treat the patient with pembrolizumab or without pembrolizumab. Initially, eligible patients were randomly assigned in a 1:1 ratio to the selpercatinib group or the control group; however, on amendment of the protocol, patients were randomly assigned in a 2:1 ratio to the selpercatinib group or the control group, and therefore the final ratio of randomization was 1.6:1. After the completion of four cycles of control treatment without progressive disease, patients in the control group could continue to receive pemetrexed with or without pembrolizumab. Pembrolizumab was administered for a maximum of 35 cycles. Because of differences in treatment administration between the groups, the trial was open label to patients and investigators; however, the sponsor did not review or analyze aggregate data and response assessments or the assessments of disease progression conducted by blinded independent central review and by the investigator in accordance with RECIST, version 1.1.13 Patients were allowed to continue selpercatinib treatment after the occurrence of disease progression at the discretion of the investigator and with sponsor approval if there was clinical benefit. Patients who were randomly assigned to the control group and who had disease progression confirmed by blinded independent central review were eligible for optional crossover to selpercatinib. The efficacy and safety results among the patients who crossed over are not reported here.[4]

Absorption, Distribution and Excretion
In patients with locally advanced or metastatic solid tumours receiving 160 mg of selpercatinib twice daily, steady-state was achieved after approximately 7 days, with a Cmax of 2,980 (CV 53%) and AUC0-24h of 51,600 (CV 58%). The absolute bioavailability is between 60 and 82% (mean 73%), and the median tmax is two hours. Food has no apparent effect on the AUC or Cmax of selpercatinib. Patients with hepatic impairment display a concomitant increase in AUC0-INF for mild (7%), moderate (32%), and severe (77%) impairment.
Selpercatinib administered as a single 160 mg dose in healthy individuals was primarily recovered in feces (69%, 14% unchanged) and urine (24%, 12% unchanged).
Selpercatinib has an apparent volume of distribution of 191 L; the volume of distribution increases with increasing body weight.
Selpercatinib has an apparent clearance of 6L/h; the clearance increases with increasing body weight.

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Metabolism / Metabolites
Selpercatinib is predominantly metabolized in the liver by CYP3A4.

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Biological Half-Life
Selpercatinib has a half-life of 32 hours in healthy individuals.

Hepatotoxicity
In the prelicensure clinical trials of selpercatinib in patients with thyroid and non-small cell lung cancer, liver test abnormalities were frequent although usually mild. Some degree of ALT elevation arose in up to 55% of selpercatinib treated patients and were above 5 times the upper limit of normal (ULN) in 10% to 12%, arising mostly within the first few months of therapy; the median onset was at 6 weeks but with a range of 1 day to more than 2 years. In the preregistration trials that enrolled 531 patients, serum aminotransferase elevations led to dose interruptions and modifications in 5% to 6% but complete discontinuation in less than 1% of patients. ALT levels were closely monitored and did not lead to clinically apparent liver injury with jaundice or deaths from liver disease. Thus, selpercatinib therapy is associated with a high rate of transient serum enzyme elevations but has not been definitely linked to instances of clinically apparent liver injury with jaundice. The product label for selpercatinib recommends monitoring for routine liver tests before, at 2 week intervals during the first 3 months of therapy, and monthly thereafter as clinically indicated.
Likelihood score: E* (unproven but suspect cause of clinically apparent liver injury).

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Effects During Pregnancy and Lactation
◉ Summary of Use during Lactation
No information is available on the use of selpercatinib during breastfeeding. Because selpercatinib is 97% bound to plasma proteins, the amounts in milk are likely to be low. However, the manufacturer recommends that mothers should not breastfeed during treatment with selpercatinib and for 1 week after the final dose.
◉ Effects in Breastfed Infants
Relevant published information was not found as of the revision date.
◉ Effects on Lactation and Breastmilk
Relevant published information was not found as of the revision date.

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Protein Binding
Selpercatinib displays 97% _in vitro_ protein binding independent of concentration and a blood-plasma concentration ratio of 0.7.

[1]. Quantitative bioanalytical assay for the selective RET inhibitors selpercatinib and pralsetinib in mouse plasma and tissue homogenates using liquid chromatography-tandem mass spectrometry. J Chromatogr B Analyt Technol Biomed Life Sci. 2020 Jun 15;1147:122131.

[2]. Substituted pyrazolo[1,5-a]pyridine compounds as ret kinase inhibitors. WO2018071447A1.

[3]. SD898_E901 RET Deletion Is Oncogenic, Responds to Selpercatinib, and Treatment Resistance Can Arise Via RET-Independent Mechanisms. JCO Precis Oncol. 2023 Aug:7:e2300052.

[4]. First-Line Selpercatinib or Chemotherapy and Pembrolizumab in RET Fusion-Positive NSCLC. N Engl J Med. 2023 Nov 16;389(20):1839-1850.

Pharmacodynamics
Selpercatinib exerts anti-tumour activity in specific cancers through inhibition of mutated forms of RET tyrosine kinases. Due to its increased specificity for RET over other tyrosine kinases, selpercatinib is thought to have an improved safety profile compared to other multi-kinase inhibitors. Despite this, selpercatinib treatment is associated with hepatotoxicity, hypertension, QT interval prolongation, hemorrhagic events, risk of impaired wound healing, and embryo-fetal toxicity; some patients may also exhibit hypersensitivity to selpercatinib.

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Selpercatinib is a kinase inhibitor with enhanced specificity for RET tyrosine kinase receptors (RTKs) over other RTK classes. Enhanced RET (Rearranged during transfection) oncogene expression is a hallmark of many cancers. Although multikinase inhibitors, including [cabozantinib], [ponatinib], [sorafenib], [sunitinib], and [vandetanib], have shown efficacy in RET-driven cancers, their lack of specificity is generally associated with substantial toxicity. Selpercatinib (LOXO-292) and pralsetinib (BLU-667) represent the first generation of specific RET RTK inhibitors for the treatment of RET-driven cancers. Although selpercatinib is currently still under investigation in clinical trial NCT04211337, it was granted accelerated FDA approval on May 8, 2020, for specific RET-driven cancer indications. It is currently marketed under the brand name RETEVMO™ by Loxo Oncology Inc. Selpercatinib is also approved by the European Commission.

Selpercatinib is a Kinase Inhibitor. The mechanism of action of selpercatinib is as a Rearranged during Transfection (RET) Inhibitor, and Cytochrome P450 2C8 Inhibitor, and Cytochrome P450 3A Inhibitor, and P-Glycoprotein Inhibitor, and Breast Cancer Resistance Protein Inhibitor, and Multidrug and Toxin Extrusion Transporter 1 Inhibitor.

Selpercatinib is an oral selective inhibitor of the tyrosine kinase receptor encoded by RET (rearranged during transfection), a proto-oncogene which is mutated or altered in many cancers such a medullary thyroid cancer and non-small cell lung cancer. Serum aminotransferase elevations are common during therapy with selpercatinib and can lead to dose modifications or drug discontinuation, but clinically apparent liver injury with jaundice has not been described with its use.

Selpercatinib is an orally bioavailable selective inhibitor of wild-type, mutant and fusion products involving the proto-oncogene receptor tyrosine kinase rearranged during transfection (RET), with potential antineoplastic activity. Upon oral administration, selpercatinib selectively binds to and targets wild-type RET as well as various RET mutants and RET-containing fusion products. This results in an inhibition of cell growth of tumors cells that exhibit increased RET activity. In addition, selpercatinib targets, binds to and inhibits vascular endothelial growth factor receptor 1 (VEGFR1) and 3 (VEGFR3), and fibroblast growth factor receptor 1 (FGFR1), 2 (FGFR2), and 3 (FGFR3). RET overexpression, activating mutations, and fusions result in the upregulation and/or overactivation of RET tyrosine kinase activity in various cancer cell types; dysregulation of RET activity plays a key role in the development and progression of these cancers.

SELPERCATINIB is a small molecule drug with a maximum clinical trial phase of IV (across all indications) that was first approved in 2020 and has 7 approved and 3 investigational indications.

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Background: Selpercatinib, a highly selective potent and brain-penetrant RET inhibitor, was shown to have efficacy in patients with advanced RET fusion-positive non-small-cell lung cancer (NSCLC) in a nonrandomized phase 1-2 study. Methods: In a randomized phase 3 trial, we evaluated the efficacy and safety of first-line selpercatinib as compared with control treatment that consisted of platinum-based chemotherapy with or without pembrolizumab at the investigator's discretion. The primary end point was progression-free survival assessed by blinded independent central review in both the intention-to-treat-pembrolizumab population (i.e., patients whose physicians had planned to treat them with pembrolizumab in the event that they were assigned to the control group) and the overall intention-to-treat population. Crossover from the control group to the selpercatinib group was allowed if disease progression as assessed by blinded independent central review occurred during receipt of control treatment.[4]

2306313-13-1

2152628-33-4; 2306313-17-5 (mesylate); 2306313-13-1 (HCl); 2306313-14-2 (sulfate); 2306313-23-3; 2306313-16-4; 2306313-19-7 (besylate); 2306313-28-8 (fumarate); 2306313-27-7 (tartrate); 2306313-29-9 (citrate)

Typically exists as solid at room temperature

2.5

6-(2-hydroxy-2-methylpropoxy)-4-[6-[6-[(6-methoxypyridin-3-yl)methyl]-3,6-diazabicyclo[3.1.1]heptan-3-yl]pyridin-3-yl]pyrazolo[1,5-a]pyridine-3-carbonitrile hydrochloride

LOXO-292 HCl; ARRY 192 HCl; LOXO292 HCl; LY-3527723 HCl; CEGM9YBNGD; Serpercatinib; Ret inhibitor loxo-292; LY3527723; ARRY192; LOXO 292; ARRY-192; Selpercatinib; Retevmo

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)