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 tumors, a twice-daily dose of 160 mg selpercatinib resulted in steady-state plasma concentrations after approximately 7 days, with a Cmax of 2,980 (CV 53%) and an AUC0-24h of 51,600 (CV 58%). Absolute bioavailability ranged from 60% to 82% (mean 73%), with a median tmax of 2 hours. Food had no significant effect on the AUC or Cmax of selpercatinib. Patients with hepatic impairment showed corresponding increases in AUC0-INF values, with elevated values observed in mild (7%), moderate (32%), and severe (77%) hepatic impairment. In healthy individuals, after a single 160 mg dose of selpercatinib, the drug was primarily excreted in feces (69%, of which 14% was unchanged) and urine (24%, of which 12% was unchanged).
The apparent volume of distribution of serpatinib is 191 L; the volume of distribution increases with increasing body weight.
The apparent clearance of serpatinib is 6 L/h; clearance increases with increasing body weight.
Metabolism/Metabolites

Sepatinib is primarily metabolized in the liver via CYP3A4.
Biological Half-Life

The half-life of serpatinib in healthy individuals is 32 hours.

Hepatotoxicity
Liver dysfunction was common, but usually mild, in premarket clinical trials of selpercatinib in patients with thyroid cancer and non-small cell lung cancer. Up to 55% of patients treated with selpercatinib experienced varying degrees of ALT elevation, with 10% to 12% having ALT values exceeding five times the upper limit of normal (ULN), mostly occurring within the first few months of treatment; the median time to onset was 6 weeks, but ranged from 1 day to over 2 years. In a pre-registration trial involving 531 patients, elevated serum transaminases led to discontinuation of treatment or dose adjustment in 5% to 6% of patients, but less than 1% completely discontinued treatment. ALT levels were closely monitored, and no clinically symptomatic liver injury or death due to liver disease occurred. Therefore, selpercatinib treatment is associated with a higher incidence of transient serum enzyme elevations, but its association with clinically significant liver injury (with jaundice) has not been definitively established. The selpercatinib product information recommends routine liver function tests before treatment, every two weeks for the first three months of treatment, and monthly as needed thereafter.
Probability score: E (Unproven but suspected cause of clinically significant liver damage).

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Effects during pregnancy and lactation
◉ Overview of use during lactation
There is currently no information regarding the use of selpercatinib during lactation. Because selpercatinib binds to plasma proteins at a rate of 97%, its levels in breast milk may be very low. However, the manufacturer recommends that mothers not breastfeed during selpercatinib treatment and for one week after the last dose.
◉ Effects on breastfed infants
No published information found as of the revision date.
◉ Effects on lactation and breast milk
No published information found as of the revision date.

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Protein Binding
Selpercatinib has an in vitro protein binding rate of 97%, which is independent of concentration and has a 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 its antitumor activity in specific cancers by inhibiting mutated forms of RET tyrosine kinase. Due to its higher specificity for RET than other tyrosine kinases, Selpercatinib is considered to have better safety profiles compared to other multi-kinase inhibitors. Nevertheless, Selpercatinib treatment is still associated with hepatotoxicity, hypertension, QT interval prolongation, bleeding events, impaired wound healing, and embryo-fetal toxicity; some patients may also experience hypersensitivity to Selpercatinib. Selpercatinib is a kinase inhibitor with higher specificity for RET tyrosine kinase receptors (RTKs) compared to other RTK classes. Enhanced RET (transfection rearrangement) oncogene expression is a hallmark of many cancers. Although multi-kinase inhibitors, including cabozantinib, panatinib, sorafenib, sunitinib, and vandetanib, have shown efficacy against RET-driven cancers, they are often accompanied by significant toxicity due to their lack of specificity. Seppatinib (LOXO-292) and praltinib (BLU-667) are first-generation specific RET RTK inhibitors for the treatment of RET-driven cancers. Although serpatinib is currently under investigation in the clinical trial NCT04211337, it received accelerated approval from the FDA on May 8, 2020, for the treatment of specific RET-driven cancers. It is currently marketed by Loxo Oncology Inc. under the brand name RETEVMO™. Serpatinib has also been approved by the European Commission.
Sepatinib is a kinase inhibitor. Its mechanism of action is as a transfection rearrangement (RET) inhibitor, a cytochrome P450 2C8 inhibitor, a cytochrome P450 3A inhibitor, a P-glycoprotein inhibitor, a breast cancer resistance protein inhibitor, and a multidrug and toxin efflux transporter 1 inhibitor.
Sepatinib is an orally selective tyrosine kinase receptor inhibitor encoded by RET (transfection rearrangement). RET is a proto-oncogene that is mutated or altered in various cancers, such as medullary thyroid carcinoma and non-small cell lung cancer. Elevated serum transaminases are common during serpatinib treatment, which may lead to dose adjustments or discontinuation, but no clinically significant liver injury or jaundice has been reported with serpatinib. Serpatinib is a highly bioavailable, selective inhibitor that inhibits wild-type, mutant, and fusion products of the proto-oncogene receptor tyrosine kinase (RET), exhibiting potential antitumor activity. After oral administration, serpatinib selectively binds to and targets wild-type RET, as well as various RET mutants and RET-containing fusion products. This inhibits the growth of tumor cells with enhanced RET activity. Furthermore, serpatinib targets, binds to, and inhibits vascular endothelial growth factor receptors 1 (VEGFR1) and 3 (VEGFR3), and fibroblast growth factor receptors 1 (FGFR1), 2 (FGFR2), and 3 (FGFR3). RET overexpression, activating mutations, and fusions lead to the upregulation and/or overactivation of RET tyrosine kinase activity in various cancer cell types; RET dysregulation plays a crucial role in the development and progression of these cancers. Selpercatinib is a small molecule drug with clinical trials up to Phase IV (covering all indications), first approved in 2020, and currently has 7 approved indications and 3 investigational indications. Background: Selpercatinib is a highly selective, potent, and blood-brain barrier-crossing RET inhibitor, demonstrated in a non-randomized Phase I/II study for patients with RET fusion-positive advanced non-small cell lung cancer (NSCLC). Methods: In a randomized Phase III trial, we evaluated the efficacy and safety of first-line Selpercatinib treatment compared to control therapy (platinum-based chemotherapy with or without pembrolizumab, at the investigator's discretion). The primary endpoint was progression-free survival, assessed by a blinded independent central review in the pembrolizumab treatment intention population (i.e., patients whose physicians plan to treat them with pembrolizumab if they are assigned to the control group) and the overall treatment intention population. If disease progression occurred during the period of receiving control treatment, as assessed by a blinded independent central review, crossover from the control group to the serpatinib group was permitted. [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.)