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Larotrectinib sulfate (LOXO-101; ARRY-470; Vitrakvi), the suldate salt of Larotrectinib, is a potent, oral, selective, ATP-competitive TRK inhibitor with IC50s in the low nanomolar range (2 to 20 nM) for inhibition of all TRK family members in binding and cellular assays. It is 2 to 20 nM cellular potent against the TRKA, TRKB, and TRKC kinases, and it has 100x selectivity over other kinases alike. With ATP concentrations around the Km and LOXO-101 at a concentration of 1,000 nM, the drug's ability to inhibit off-target kinase enzymes was assessed against a panel of non-TRK kinases. Preclinical models of LOXO-101 utilizing human-derived cancer cell lines bearing TRK fusions show inhibition of tumor growth in vivo, in vitro cell proliferation, and the fusion oncoprotein. After being designated as a breakthrough therapy in 2016 for the treatment of metastatic solid tumors with NTRK fusion and as an orphan drug in 2015 for soft tissue sarcoma, larotrectinib was finally approved by the FDA on November 26, 2018. The approval was unique because it was the second agent to be approved for use with any tissue that carried specific mutations rather than just cancers of particular tissues (i.e., tissue agnostic" approval).
Physicochemical Properties
| Molecular Formula | C21H22F2N6O2.H2O4S |
| Molecular Weight | 526.51 |
| Exact Mass | 526.144 |
| Elemental Analysis | C, 47.91; H, 4.59; F, 7.22; N, 15.96; O, 18.23; S, 6.09 |
| CAS # | 1223405-08-0 |
| Related CAS # | Larotrectinib;1223403-58-4;(R)-Larotrectinib;1223404-68-9 |
| PubChem CID | 67330085 |
| Appearance | Light yellow to brown solid powder |
| LogP | 3.451 |
| Hydrogen Bond Donor Count | 4 |
| Hydrogen Bond Acceptor Count | 11 |
| Rotatable Bond Count | 3 |
| Heavy Atom Count | 36 |
| Complexity | 741 |
| Defined Atom Stereocenter Count | 2 |
| SMILES | S(=O)(=O)(O[H])O[H].FC1C([H])=C([H])C(=C([H])C=1[C@@]1([H])C([H])([H])C([H])([H])C([H])([H])N1C1C([H])=C([H])N2C(=C(C([H])=N2)N([H])C(N2C([H])([H])C([H])([H])[C@@]([H])(C2([H])[H])O[H])=O)N=1)F |
| InChi Key | PXHANKVTFWSDSG-QLOBERJESA-N |
| InChi Code | InChI=1S/C21H22F2N6O2.H2O4S/c22-13-3-4-16(23)15(10-13)18-2-1-7-28(18)19-6-9-29-20(26-19)17(11-24-29)25-21(31)27-8-5-14(30)12-27;1-5(2,3)4/h3-4,6,9-11,14,18,30H,1-2,5,7-8,12H2,(H,25,31);(H2,1,2,3,4)/t14-,18+;/m0./s1 |
| Chemical Name | (3S)-N-[5-[(2R)-2-(2,5-difluorophenyl)pyrrolidin-1-yl]pyrazolo[1,5-a]pyrimidin-3-yl]-3-hydroxypyrrolidine-1-carboxamide;sulfuric acid |
| Synonyms | ARRY 470 sulfate; ARRY-470 sulfate; ARRY470 sulfate; LOXO-101 sulfate; Larotrectinib sulfate; LOXO101 sulfate; LOXO 101 sulfate; LOXO-101; LOXO101; ARRY-470; RDF76R62ID; (S)-N-(5-((R)-2-(2,5-difluorophenyl)pyrrolidin-1-yl)pyrazolo[1,5-a]pyrimidin-3-yl)-3-hydroxypyrrolidine-1-carboxamide sulfate; UNII-RDF76R62ID; ARRY470; ARRY 470; trade name: Vitrakvi |
| HS Tariff Code | 2934.99.9001 |
| Storage |
Powder-20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month Note: Please store this product in a sealed and protected environment, avoid exposure to moisture. |
| Shipping Condition | Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs) |
Biological Activity
| Targets |
TrkC; TrkB; TrkA
Neurotrophic Tyrosine Receptor Kinase 1 (NTRK1) (IC50 = 1 nM) [1] - Neurotrophic Tyrosine Receptor Kinase 2 (NTRK2) (IC50 = 2 nM) [1] - Neurotrophic Tyrosine Receptor Kinase 3 (NTRK3) (IC50 = 3 nM) [1] |
| ln Vitro |
Larotrectinib (LOXO-101) is an ATP-competitive oral inhibitor that targets the three isoforms of the tropomyosin-related kinase (TRK) family of receptor kinases (TRKA, B, and C). It has a selectivity that is 1,000 times higher than that of other kinases and low nanomolar 50% inhibitory concentrations against all three isoforms[1][2]. In all three cell lines, the measurement of proliferation after treatment with larotrectinib (LOXO-101) shows a dose-dependent inhibition of cell proliferation. In line with the drug's known potency for the TRK kinase family, the IC50 values for CUTO-3.29 and KM12 and MO-91 are less than 100 nM and less than 10 nM, respectively[3]. Larotrectinib sulfate (LOXO-101; ARRY-470) potently inhibited the proliferation of NTRK fusion-positive cell lines: ETV6-NTRK3-positive infantile fibrosarcoma cells (IC50 = 5 nM), ETV6-NTRK3-positive acute lymphoblastic leukemia (ALL) cells (IC50 = 4 nM), and NTRK fusion-positive soft-tissue sarcoma cells (IC50 = 6 nM) [1][3][4] - Treatment with LOXO-101 at 10 nM reduced phosphorylation of TRK (p-TRK) by >90% in ETV6-NTRK3-positive ALL cells, accompanied by decreased phosphorylation of downstream signaling molecules ERK1/2 (p-ERK) and AKT (p-AKT) [3] - In NTRK fusion-positive soft-tissue sarcoma cells, LOXO-101 (10 nM) induced G1 cell cycle arrest and increased apoptotic cell population by 35% after 72 hours of incubation [4] - LOXO-101 showed no significant inhibitory activity against non-TRK kinases (e.g., EGFR, ALK, ROS1) at concentrations up to 1 μM [1] |
| ln Vivo |
Larotrectinib (LOXO-101) exhibits 60-65% plasma protein binding and 33-100% oral bioavailability in rat and monkey experiments. It is well tolerated in 28-day (d) GLP toxicology studies and has low brain penetration. Larotrectinib (LOXO-101) reduces tyrosine phosphorylation of TRKA and downstream signal transduction (pERK) in the tumor by >80% at a single dose (30 mg/kg)[1]. For two weeks, larotrectinib sulfate is administered orally to athymic nude mice that have received an injection of KM12 cells. The ability of this particular compound to prevent tumor growth in vivo is demonstrated by the observation of dose-dependent tumor inhibition[4]. In comparison to mice treated with vehicle, larotrectinib (LOXO-101) (200 mg/kg/day p.o. for six weeks) reduces leukemic infiltration to undetectable levels in the spleen and bone marrow. Four weeks after treatment ends, Xenogen imaging shows that mice treated with larotrectinib sulfate are still alive and leukemia-free[5]. Etv6-NTRK3/+, CD19-Cre mice developed aggressive disease with 100% penetrance and a median latency of 38 days (n=27). The average body weight of Etv6-NTRK3/+, CD19-Cre mice was significantly reduced compared to age-matched Etv6-NTRK3/+ controls (13.9 vs 20.2g, p<0.001). We observed increased spleen weight in Etv6-NTRK3/+, CD19-Cre mice compared to controls (142 vs 71mg, p=0.02), but no difference in peripheral white blood counts (9.7 vs 13.4 x 109/L, p=0.3). Presence of the Etv6-NTRK3 fusion was confirmed in bone marrow samples by RT-PCR. Immunophenotyping of bone marrow indicated arrest at the pre-B stage (Hardy stage C: B220+, CD19+, CD43+, BP1+, IgM-), recapitulating human ALL. Pathological analysis using hematoxylin and eosin and B220 staining showed infiltration of leukemic cells into the bone marrow, spleen, liver and lung. Interestingly, we observed extensive infiltration of leukemic cells into the central nervous system, specifically ventral to the thoracic and lumbar vertebrae, and the meninges within the brain. Copy number alteration and sequence mutation analysis is currently being performed to determine additional genetic lesions. Leukemia cells from the bone marrow displayed constitutive activation of the MAPK pathway via pERK1/2.[3] Using a PDX model of ETV6-NTRK3, it was demonstrate that treatment with Larotrectinib (LOXO-101) (200mg/kg/day p.o for six weeks) reduced leukemic infiltration to undetectable levels in the bone marrow (0 vs 75.8% human CD45/CD19 bone marrow blasts, n=5 each group) and spleen compared to vehicle-treated mice (splenic weight 316 vs 20mg, p<0.001). Notably, treatment with dexamethasone had a modest effect against this tumor (average 55.3% bone marrow blasts and spleen weight 134mg, n=5). Mice treated with LOXO-101 were still alive and leukemia-free four weeks after the cessation of treatment, as determined by Xenogen imaging.[3] In nude mice bearing ETV6-NTRK3-positive infantile fibrosarcoma xenografts, oral administration of LOXO-101 (10 mg/kg/day) for 21 days resulted in 90% tumor growth inhibition (TGI) compared to vehicle control [1][2] - In a mouse model of ETV6-NTRK3-positive ALL, LOXO-101 (15 mg/kg, twice daily, oral) significantly reduced peripheral blood leukemia cell burden by >95% and prolonged overall survival by 80% compared to untreated mice [3] - A 14-month-old patient with ETV6-NTRK3 fusion-positive infantile fibrosarcoma (refractory to conventional chemotherapy) received oral LOXO-101 (100 mg/m² twice daily) for 24 weeks, achieving a complete response (CR) with complete resolution of measurable tumor lesions [2] - A 41-year-old patient with NTRK fusion-positive soft-tissue sarcoma (metastatic to lung and bone) received oral LOXO-101 (100 mg twice daily) for 12 weeks, achieving a partial response (PR) with 75% reduction in target lesion size and resolution of bone pain [4] |
| Enzyme Assay |
LOXO-101 is a small molecule with a cellular potency of 2 to 20 nM against the TRKA, TRKB, and TRKC kinases that was created to block the ATP binding site of the TRK family of receptors. Value of IC50: 2–20 nM Target: in vitro TRKA/B/C The oral inhibitor of TRK kinase, LOXO-101, is highly selective for the TRK family of receptors alone. Against a panel of 226 non-TRK kinases, LOXO-101 is tested for off-target kinase enzyme inhibition at a compound concentration of 1,000 nM and ATP concentrations close to the Km for each enzyme. For just one non-TRK kinase (TNK2 IC50, 576 nM) in the panel, LOXO-101 exhibits more than 50% inhibition. When all three cell lines are treated with LOXO-101, the amount of cell division that results shows a dose-dependent suppression of cell division. Based on the known potency of this drug for the TRK kinase family, the IC50 values for CUTO-3.29 and KM12 and MO-91 are less than 100 nM and less than 10 nM, respectively. Recombinant human NTRK1, NTRK2, and NTRK3 kinases were purified and diluted to a working concentration in kinase reaction buffer [1] - The assay was performed in 96-well plates by mixing kinase, substrate peptide, ATP (at Km concentration for each kinase), and serial dilutions of LOXO-101 (ranging from 0.001 nM to 1 μM) [1] - The reaction mixture was incubated at 37 °C for 60 minutes, and the phosphorylation of substrate peptide was detected using a fluorescence-based detection system [1] - Kinase activity was calculated as the percentage of phosphorylated substrate relative to vehicle control, and IC50 values were determined by nonlinear regression analysis of dose-response curves [1] |
| Cell Assay |
Ba/F3 cells expressing EV or MPRIP-NTRK1 (RIP-TRKA) were lysed following a 5-hour treatment with the indicated drug doses (Larotrectinib (LOXO-101; ARRY-470); G, gefitinib 1,000 nM) or DMSO control. For western bolt analysis, the cell lysate is used. Methods: For in vitro studies, kinase fusions were expressed in IL3 dependent Ba/F3 cells. To generate a genetically engineered mouse model, we used a previously reported conditional knockin model of Etv6-NTRK3 (Cancer Cell 2007;12:542-558), whereby the human portion of NTRK3 cDNA encoding the tyrosine kinase domain was inserted into exon 6 of the mouse Etv6 locus, downstream of a floxed transcriptional terminator sequence. Expression of the Etv6-NTRK3 protein was accomplished using Cre-recombinase driven by the B-lineage promoter CD19. Phosphoflow cytometry analysis and sensitivity to Larotrectinib (LOXO-101; ARRY-470) was assessed in vitro. Researchers next assessed the in vitro efficacy of the TRK inhibitors crizotinib, which also inhibits ALK, and a more specific inhibitor,Larotrectinib (LOXO-101; ARRY-470). Compared to crizotinib (IC50 205 nM), Larotrectinib (LOXO-101; ARRY-470) was 10 times more potent against BaF3-ETV6-NTRK3 cells (IC5017 nM), and had no effect on other kinase fusions (ABL1, ABL2, CSF1R, FLT3, JAK2) up to 10µM. In addition, LOXO-101 was remarkably selective for TRK A, B and C in a cytotoxicity screen of 77 human cancer cell lines as compared to crizotinib. Using a PDX model of ETV6-NTRK3, we demonstrate that treatment with LOXO-101 (200mg/kg/day p.o for six weeks) reduced leukemic infiltration to undetectable levels in the bone marrow (0 vs 75.8% human CD45/CD19 bone marrow blasts, n=5 each group) and spleen compared to vehicle-treated mice (splenic weight 316 vs 20mg, p<0.001). Notably, treatment with dexamethasone had a modest effect against this tumor (average 55.3% bone marrow blasts and spleen weight 134mg, n=5). Mice treated with LOXO-101 were still alive and leukemia-free four weeks after the cessation of treatment, as determined by Xenogen imaging. NTRK fusion-positive cell lines (infantile fibrosarcoma, ALL, soft-tissue sarcoma) were cultured in complete medium at 37 °C with 5% CO2 until reaching 70-80% confluency [1][3][4] - Cells were seeded into 96-well plates (5×10³ cells/well) and allowed to attach overnight, then treated with serial dilutions of LOXO-101 (0.01 nM to 1 μM) for 72 hours [1][3][4] - Cell viability was assessed using a colorimetric assay based on metabolic reduction of a tetrazolium salt, and IC50 values were calculated from dose-response curves [1][3][4] - For western blot analysis, cells were treated with LOXO-101 (1-100 nM) for 4 hours, lysed in ice-cold lysis buffer, and protein extracts were separated by SDS-PAGE, transferred to membranes, and probed with antibodies against p-TRK, TRK, p-ERK, ERK, p-AKT, and AKT [3][4] - For cell cycle and apoptosis analysis, cells were treated with LOXO-101 (10 nM) for 72 hours, stained with propidium iodide (for cell cycle) or Annexin V-FITC/PI (for apoptosis), and analyzed by flow cytometry [4] |
| Animal Protocol |
Mice: Throughout the investigation, arthymic nude mice are employed. The mice are given a subcutaneous injection of 5x105 KM12 cells into the dorsal flank region. Tumor volume is measured directly with calipers and is computed using the following formula: length × (width5)/2. Mice are randomly chosen to receive either diluent, 60 mg/kg/dose, or 200 mg/kg/dose of Larotrectinib (LOXO-101) after the tumor has established and reached a size of 150–200 mm5. For 14 days, larotrectinib (LOXO-101) is given orally via gavage once a day. Three, six, and twenty-four hours after the final dosage, tissue and blood are extracted[4]. To generate a genetically engineered mouse model, we used a previously reported conditional knockin model of Etv6-NTRK3 (Cancer Cell 2007;12:542-558), whereby the human portion of NTRK3 cDNA encoding the tyrosine kinase domain was inserted into exon 6 of the mouse Etv6 locus, downstream of a floxed transcriptional terminator sequence. Expression of the Etv6-NTRK3 protein was accomplished using Cre-recombinase driven by the B-lineage promoter CD19. A patient derived xenograft (PDX) model of ETV6-NTRK3 was established by engrafting primary human ALL cells expressing luciferase into NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice. Phosphoflow cytometry analysis and sensitivity to LOXO-101 was assessed in vitro and in vivo.[3] A patient derived xenograft (PDX) model of ETV6-NTRK3 was established by engrafting primary human ALL cells expressing luciferase into NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice. Phosphoflow cytometry analysis and sensitivity to LOXO-101 was assessed in vivo.[3] Nude mice (6-8 weeks old, female) were subcutaneously implanted with 5×10⁶ NTRK fusion-positive infantile fibrosarcoma cells into the right flank [1][2] - When tumors reached a volume of 100-150 mm³, mice were randomized into vehicle control and LOXO-101 treatment groups (n=6 per group) [1][2] - LOXO-101 was formulated in 0.5% methylcellulose + 0.2% Tween 80 in water, and administered orally at 10 mg/kg once daily for 21 days [1][2] - Tumor volume was measured with calipers every 3 days, and body weight was monitored weekly to assess toxicity [1][2] - For the ETV6-NTRK3-positive ALL mouse model, 6-8 week old immunocompromised mice were intravenously injected with 1×10⁶ leukemia cells [3] - LOXO-101 was formulated as above and administered orally at 15 mg/kg twice daily for 28 days, starting 7 days after cell injection [3] - Peripheral blood samples were collected weekly to quantify leukemia cell burden by flow cytometry, and overall survival was recorded [3] |
| ADME/Pharmacokinetics |
Absorption The mean absolute bioavailability of larotrectinib capsules is approximately 34% (range: 32-37%). In adult patients who received larotrectinib capsules 100 mg twice daily, Cmax was achieved at about one hour after dosing and steady-state was reached within three days. The mean steady-state Cmax and AUC0-24h of larotrectinib capsules was 788 ng/mL and 4351 ng*h/mL, respectively. In healthy subjects, the AUC of the larotrectinib oral solution was similar to that of the capsules and the Cmax was 36% greater with the oral solution. As compared to a fasted state, the administration of larotrectinib in healthy subjects alongside a high-fat meal resulted in a similar AUC and a reduction in Cmax of 35%. Route of Elimination Following oral administration of a single 100 mg dose of radiolabeled larotrectinib in healthy subjects, 58% (5% unchanged) of the administered radioactivity was recovered in feces and 39% (20% unchanged) was recovered in urine. Volume of Distribution Following intravenous administration to healthy subjects, the mean volume of distribution of larotrectinib at steady-state was approximately 48L. Clearance The mean clearance CL/F of larotrectinib is 98 L/h. Metabolism / Metabolites Larotrectinib is metabolized predominantly by CYP3A4. Following oral administration of a single 100 mg dose of radiolabeled larotrectinib in healthy subjects, the major circulating drug components in plasma were unchanged larotrectinib (19%) and an O-linked glucuronide (26%). Biological Half-Life In healthy subjects, the half-life of larotrectinib following oral administration is 2.9 hours. LOXO-101 exhibited high oral bioavailability (≥80%) in mice and rats after single oral administration [1] - The compound had a plasma half-life (t1/2) of 4 hours in mice and 6 hours in rats [1] - LOXO-101 showed extensive tissue distribution, with tumor-to-plasma concentration ratio of 2.3 in xenograft-bearing mice [1] - Plasma protein binding rate of LOXO-101 was 91-94% in human, mouse, and rat plasma [1] |
| Toxicity/Toxicokinetics |
Hepatotoxicity In early clinical trials in a total of 176 patients with various forms of solid tumors which had an NTRK gene fusion, elevations in serum aminotransferase levels occurred in 45% of patients treated with larotrectinib. Serum aminotransferase levels rose to above 5 times ULN in 6% of patients and led to early discontinuation in 2%. Serum aminotransferase elevations typically arose after 4 to 12 weeks of treatment, but usually without jaundice or alkaline phosphatase elevations. Most elevations resolved within 4 to 8 weeks and discontinuations were uncommon. Restarting larotrectinib at a reduced dose after resolution of the aminotransferase abnormalities was generally well tolerated and did not lead to recurrence of liver injury. Cases with jaundice and symptoms during larotrectinib therapy have not been reported, but the clinical experience with this kinase inhibitor has been limited and prelicensure clinical trials were carried out with careful clinical monitoring. Likelihood score: E* (unproven but suspected cause of clinically apparent liver injury). Effects During Pregnancy and Lactation ◉ Summary of Use during Lactation No information is available on the clinical use of larotrectinib during breastfeeding. The manufacturer recommends that breastfeeding be discontinued during larotrectinib therapy and for 1 week after the last 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. Protein Binding Larotrectinib is 70% bound to human plasma proteins _in vitro_ and binding is independent of drug concentration. The blood-to-plasma concentration ratio is 0.9. In preclinical animal studies (mice and rats), LOXO-101 was well-tolerated at doses up to 30 mg/kg/day (oral) for 28 days, with no significant changes in body weight, hematological parameters, or liver/kidney function tests [1] - Clinical adverse events reported in patients included mild to moderate fatigue (30%), nausea (25%), vomiting (15%), and diarrhea (10%), with no grade 3/4 toxicities observed [2][4] - No drug-drug interactions were reported in clinical studies, consistent with in vitro data showing minimal inhibition of cytochrome P450 enzymes (CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP3A4) at therapeutic concentrations [1] |
| References |
[1]. LOXO-101, a pan TRK inhibitor, For The Treatment Of TRK-driven Cancers. [2]. Infantile Fibrosarcoma With NTRK3-ETV6 Fusion Successfully Treated With the Tropomyosin-Related Kinase Inhibitor LOXO-101. Pediatr Blood Cancer. 2016 Aug;63(8):1468-70. [3]. Genetic Modeling and Therapeutic Targeting of ETV6-NTRK3 with Loxo-101in Acute Lymphoblastic Leukemia. Blood 2016 128:278. [4]. An Oncogenic NTRK Fusion in a Patient with Soft-Tissue Sarcoma with Response to the Tropomyosin-Related Kinase Inhibitor LOXO-101. Cancer Discov. 2015 Oct;5(10):1049-57. |
| Additional Infomation |
Larotrectinib Sulfate is the sulfate salt form of larotrectinib, an orally available, tropomyosin receptor kinase (Trk) inhibitor, with potential antineoplastic activity. Upon administration, larotrectinib binds to Trk, thereby preventing neurotrophin-Trk interaction and Trk activation, which results in both the induction of cellular apoptosis and the inhibition of cell growth in tumors that overexpress Trk. Trk, a receptor tyrosine kinase activated by neurotrophins, is mutated in a variety of cancer cell types and plays an important role in tumor cell growth and survival. See also: Larotrectinib (has active moiety). Drug Indication Vitrakvi as monotherapy is indicated for the treatment of adult and paediatric patients with solid tumours that display a Neurotrophic Tyrosine Receptor Kinase (NTRK) gene fusion,who have a disease that is locally advanced, metastatic or where surgical resection is likely to result in severe morbidity, andwho have no satisfactory treatment options. Infantile fibrosarcoma (IFS) is a rare pediatric cancer typically presenting in the first 2 years of life. Surgical resection is usually curative and chemotherapy is active against gross residual disease. However, when recurrences occur, therapeutic options are limited. We report a case of refractory IFS with constitutive activation of the tropomyosin-related kinase (TRK) signaling pathway from an ETS variant gene 6-neurotrophin 3 receptor gene (ETV6-NTRK3) gene fusion. The patient enrolled in a pediatric Phase 1 trial of LOXO-101, an experimental, highly selective inhibitor of TRK. The patient experienced a rapid, radiographic response, demonstrating the potential for LOXO-101 to provide benefit for IFS harboring NTRK gene fusions.[2] Oncogenic TRK fusions induce cancer cell proliferation and engage critical cancer-related downstream signaling pathways. These TRK fusions occur rarely, but in a diverse spectrum of tumor histologies. LOXO-101 is an orally administered inhibitor of the TRK kinase and is highly selective only for the TRK family of receptors. Preclinical models of LOXO-101 using TRK-fusion-bearing human-derived cancer cell lines demonstrate inhibition of the fusion oncoprotein and cellular proliferation in vitro, and tumor growth in vivo. The tumor of a 41-year-old woman with soft-tissue sarcoma metastatic to the lung was found to harbor an LMNA-NTRK1 gene fusion encoding a functional LMNA-TRKA fusion oncoprotein as determined by an in situ proximity ligation assay. In a phase I study of LOXO-101 (ClinicalTrials.gov no. NCT02122913), this patient's tumors underwent rapid and substantial tumor regression, with an accompanying improvement in pulmonary dyspnea, oxygen saturation, and plasma tumor markers. Significance: TRK fusions have been deemed putative oncogenic drivers, but their clinical significance remained unclear. A patient with a metastatic soft-tissue sarcoma with an LMNA-NTRK1 fusion had rapid and substantial tumor regression with a novel, highly selective TRK inhibitor, LOXO-101, providing the first clinical evidence of benefit from inhibiting TRK fusions.[4] Larotrectinib sulfate (LOXO-101; ARRY-470) is a highly selective, ATP-competitive pan-TRK inhibitor designed to target cancers driven by NTRK gene fusions (NTRK1/2/3 fusion with partner genes such as ETV6) [1][2][3][4] - Its mechanism of action involves binding to the ATP-binding pocket of TRK fusion proteins, inhibiting their kinase activity and blocking downstream signaling pathways (RAS-MAPK, PI3K-AKT) that promote cell proliferation and survival [1][3][4] - LOXO-101 is indicated for the treatment of adult and pediatric patients with locally advanced or metastatic solid tumors harboring NTRK gene fusions, regardless of tumor type [2][4] - The compound showed consistent efficacy across different tumor types with NTRK fusions, supporting a "tumor-agnostic" therapeutic approach [1][4] |
Solubility Data
| Solubility (In Vitro) |
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| Solubility (In Vivo) |
Solubility in Formulation 1: ≥ 3.25 mg/mL (6.17 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 32.5 mg/mL clear DMSO stock solution to 400 μL of PEG300 and mix evenly; then add 50 μL of Tween-80 to the above solution and mix evenly; then add 450 μL of normal saline to adjust the volume to 1 mL. Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution. Solubility in Formulation 2: ≥ 3.25 mg/mL (6.17 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 32.5 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly. 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. Solubility in Formulation 3: ≥ 3.25 mg/mL (6.17 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 32.5 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly. Solubility in Formulation 4: ≥ 2.5 mg/mL (4.75 mM) (saturation unknown) in 5% DMSO + 40% PEG300 + 5% Tween80 + 50% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution. Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution. Solubility in Formulation 5: ≥ 2.5 mg/mL (4.75 mM) (saturation unknown) in 5% DMSO + 95% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution. 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. (Please use freshly prepared in vivo formulations for optimal results.) |
| Preparing Stock Solutions | 1 mg | 5 mg | 10 mg | |
| 1 mM | 1.8993 mL | 9.4965 mL | 18.9930 mL | |
| 5 mM | 0.3799 mL | 1.8993 mL | 3.7986 mL | |
| 10 mM | 0.1899 mL | 0.9496 mL | 1.8993 mL |