DDX5 (p68) – a multifunctional DEAD-box RNA helicase and master regulator oncoprotein. FL118 binds directly to DDX5 with high affinity (KD = 34.4 nM) and induces its dephosphorylation and degradation via the ubiquitin-proteasome pathway. This leads to downstream inhibition of survivin, Mcl-1, XIAP, cIAP2, c-Myc, and mutant Kras [2].
Cytoglobin (CYGB) – FL118 upregulates CYGB expression, which mediates its anti-proliferative and anti-migratory effects in ovarian cancer cells [1].
FL118 targets multiple oncogenic proteins and pathways. Primary targets include Survivin (an inhibitor of apoptosis protein), Mcl-1 (myeloid cell leukemia-1), XIAP (X-linked inhibitor of apoptosis protein), and cIAP2 (cellular inhibitor of apoptosis protein 2). FL118 inhibits these survival genes selectively and independently in a p53 status-independent manner. The compound also targets the oncoprotein DDX5 (p68), binding to it to induce dephosphorylation and degradation. FL118 inhibits the PI3K/AKT/mTOR signaling pathway and the Wnt/β-catenin signaling pathway, which are critical for cancer cell proliferation, survival, and metastasis. Through Wnt/β-catenin inhibition, FL118 suppresses epithelial-mesenchymal transition (EMT), reducing cancer cell migration and invasion. The compound also affects the expression levels of vimentin and E-cadherin, key markers of EMT. This multi-target profile distinguishes FL118 from traditional camptothecin analogs and contributes to its potent anticancer activity against various cancer types, including those resistant to conventional therapies.

The proliferation of ES-2 and SK-O-V3 cells is inhibited by FL118 (0-200 nM; 24, 48, and 72 hours) [1]. The migration of ES-2 and SK-O-V3 cells is inhibited by FL118 (0-100 nM; 0 and 24 hours) [1]. FL118 (0-100 nM; 48 hours) has an impact on cytoglobin (CYGB) expression levels [1]. In ovarian cancer cells, FL118 (10 and 100 nM; 48 h) alters the expression levels of vimentin and E-cadherin and suppresses the PI3K/AKT/mTOR signaling pathway [1]. In 6 and 24 hours, FL118 (0-100 nM) dephosphorylates and breaks down DDX5 [2]. Through control of DDX5, FL118 (0-500 nM; 24, 48, 72 hours) modulates survivin, McL-1, XIAP, cIAP2, c-MYc, and mKras [2]. Significant cytotoxic efficacy against three tumor cell lines (A549, MDA-MB-231, and RM-1 cells) was demonstrated by FL118 (0-1 μM, 24 hours) [3]. FL118 (0–10 nM, 48 hours) causes A549 cells to undergo apoptosis and enhances the synthesis of PARP cleavage [3]. A549 cells are primarily arrested in the G2/M phase by FL118 (0–10 nM, 48 hours) [3].

---

FL118 inhibits the proliferation of A549 (lung), MDA-MB-231 (breast), and RM-1 (mouse prostate) cancer cells with IC50 values ranging from 2.32 nM to 4.53 μM. In A549 cells, IC50 = 8.94 ± 1.54 nM; in MDA-MB-231 cells, IC50 = 24.73 ± 13.82 nM; in RM-1 cells, IC50 = 69.19 ± 8.34 nM. In comparison, irinotecan showed IC50 values of 9.14 μM (A549) and 7.82 μM (MDA-MB-231) [3].
In ovarian cancer ES-2 and SK-OV-3 cells, FL118 inhibits cell proliferation and migration in a dose- and time-dependent manner. At 100 nM, FL118 significantly reduces cell viability and migration distance after 24-72 h. FL118 upregulates cytoglobin (CYGB) mRNA and protein expression in a dose-dependent manner, and CYGB knockdown partially reverses FL118's anti-proliferative and anti-migratory effects. FL118 also inhibits PI3K/AKT/mTOR signaling (increases p-AKT and p-mTOR) and modulates EMT markers (increases E-cadherin, decreases vimentin) [1].
In HCT-8 colon cancer cells, FL118 (1-100 nM) inhibits survivin, Mcl-1, XIAP, cIAP2, and c-Myc expression. It is approximately 25-fold more potent than topotecan in inhibiting cell growth and colony formation. FL118 is not a substrate of P-gp/MDR1 or ABCG2 efflux pumps, and its efficacy is not affected by these transporters. FL118 exhibits high Caco-2 permeability (Papp = 6.76-8.86 × 10⁻⁶ cm/s) with a very low efflux ratio (1.0-1.2) [4].
In vitro studies demonstrate that FL118 (0-200 nM; 24, 48, and 72 h) suppresses cell proliferation and migration in ovarian cancer cell lines ES-2 and SK-OV-3. The compound influences CYGB (cytoglobin) expression and inhibits the PI3K/AKT/mTOR pathway, altering vimentin and E-cadherin levels. FL118 (10 and 100 nM; 48 h) inhibits PI3K/AKT/mTOR signaling and affects vimentin and E-cadherin expression in ovarian cancer cells. FL118 (0-500 nM; 0-72 h) induces dephosphorylation and degradation of DDX5, regulating expression of survivin, MCL-1, XIAP, cIAP2, c-Myc, and mKras. FL118 (0-1 µM; 24, 48 h) exhibits cytotoxicity against A549 (lung), MDA-MB-231 (breast), and RM-1 (prostate) cancer cell lines, enhancing PARP cleavage and triggering apoptosis. In A549 cells, FL118 primarily arrests cells at the G2/M phase of the cell cycle. FL118 also inhibits epithelial-mesenchymal transition through the Wnt/β-catenin signaling pathway, inhibiting migration and invasion of human breast cancer cells. The compound inhibits cancer stem cell-like properties, which are associated with tumor initiation, metastasis, and drug resistance.

FL118 inhibits antitumor activity at doses of 5 and 10 mg/kg, taken once a week for 20 days [1]. Intraperitoneally administered FL118 (0-1.5 mg/kg, five times per diem) efficiently eradicates human colon and head and neck tumors resistant to topotecan or irinotecan [4]. FL118 has good pharmacokinetic properties when given intravenously at a dose of 1.5 mg/kg [4]. Female SCID mice's FL118 pharmacokinetic parameters [4]. Sample FaDu SW620 Plasma T1/2 (hr) 6.852 12.75 1.788 Tmax (hr) 0.167 0.167 0.167 Cmax (ng/g, mL) 115 158 43 AUC (hr*ng/g) 413 842 82 AUC∞ (hr*ng/g ) 448 897 104 AUC% Extrap (%) 7.74 6.17 21.7 Vz (g/kg) (ml/kg) 33052 30742 36849 Cl (g/hr/kg) (ml/hr/kg) 3343 1671 14287

---

In mice bearing irinotecan-resistant FaDu head-and-neck tumors, FL118 (1.5 mg/kg IP, q2d × 5) effectively eliminated resistant tumors; some regressed tumors that relapsed responded to a second cycle of FL118 treatment [4].
In mice bearing topotecan-resistant FaDu tumors, FL118 (1-1.5 mg/kg IP, q2d × 5) effectively eliminated resistant tumors [4].
In HCT116 colon carcinoma xenografts, FL118 (10 mg/kg IP, once daily for 14 days) inhibited tumor volume by 76%, superior to 5-FU (41% inhibition) and vorinostat (26% inhibition) [4].
In human PDAC patient-derived xenograft (PDX) tumors, FL118 (2.5 mg/kg oral, weekly × 4) regressed PDX19015 and PDX17624 tumors with high DDX5 expression, while PDX12872 with low DDX5 expression showed less sensitivity. Combination with low-dose gemcitabine (40 mg/kg) eliminated PDX12872 tumors [2].
In CRC xenografts, FL118 (5 mg/kg oral, weekly × 4) effectively inhibited tumor growth in high DDX5-expressing SW620 and SW837 tumors, while low DDX5-expressing SW480 and SW948 tumors showed poor sensitivity [2].
In ES-2 ovarian cancer xenografts, FL118 (5 or 10 mg/kg oral, once weekly for 20 days) showed superior antitumor activity compared to topotecan (2 mg/kg, 5×/week). At 10 mg/kg, 60% of tumors were completely abolished. FL118 upregulated CYGB expression in tumor tissues [1].
In a mouse intratracheal pharmacodynamic model, FL118 inhibited IL-6-induced lung pSTAT3 (JAK1/JAK2) with an ED50 of approximately 3 μg/animal [4].
In a mouse ear dermal model, 4% topical FL118 reduced IL-23-induced ear swelling by 48% over 11 days [4].
In vivo studies show that FL118 (5 and 10 mg/kg; p.o.; once a week for 20 days) dose-dependently suppressed ES-2 ovarian tumor growth in female BALB/c nude mice by upregulating CYGB expression. FL118 (0-1.5 mg/kg; i.p.; once every other day for five doses) effectively eliminated human colon and head-and-neck tumors that were resistant to irinotecan or topotecan, demonstrating its potential to overcome drug resistance. FL118 (1.5 mg/kg; i.v.; single dose) demonstrated favorable pharmacokinetic profiles. The compound is orally active, making it suitable for convenient administration in therapeutic settings. The antitumor activity of FL118 has been demonstrated across multiple cancer types including ovarian, breast, lung, prostate, colon, and head-and-neck cancers. The compound's ability to target multiple survival genes and overcome resistance to conventional chemotherapeutics positions it as a promising candidate for further development in oncology.

For FL118 binding to DDX5, isothermal titration calorimetry (ITC) was performed using purified Flag-DDX5 protein (10 μM) and FL118 (100 μM) in 1× PBS (pH 7.4) with 8% DMSO. The compound was titrated into the protein cell by 20 injections over 60 min (one injection per 3 min) at 25°C. The binding affinity (KD) was calculated as 34.4 nM. For Top1, the KD was 315 nM; no binding to BSA was detected [2].
For FL118 affinity purification, FL118 was coupled to agarose resin beads via a diaminodipropylamine linker through a Mannich reaction. Cancer cell lysates were passed through the FL118 affinity column and a control column in parallel. After stringent washing, bound proteins were eluted with 8 M urea, concentrated, and separated by SDS-PAGE. The ~70 kDa protein band was identified as DDX5 by mass spectrometry [2].
For Caco-2 permeability assay, Caco-2 cell monolayers were grown on collagen-coated polycarbonate membranes. FL118 (1 μM) was added to apical or basolateral side with or without valspodar (1 μM, P-gp inhibitor). Samples were taken at 120 min and analyzed by LC-MS/MS. Apparent permeability (Papp) and efflux ratio were calculated. FL118 showed high permeability (Papp = 6.76-8.86 × 10⁻⁶ cm/s) and low efflux ratio (1.0-1.2) [4].
In vitro enzyme/receptor binding assays for FL118 are not applicable in the traditional sense as the compound's mechanism involves protein degradation and signaling pathway modulation rather than simple enzyme inhibition. However, binding to the oncoprotein DDX5 has been characterized: FL118 binds to DDX5 (p68) to induce its dephosphorylation and degradation. This interaction can be studied using co-immunoprecipitation (Co-IP) assays to demonstrate physical association between FL118 and DDX5, Western blot analysis to assess DDX5 phosphorylation and degradation, and ubiquitination assays to determine whether FL118 promotes DDX5 ubiquitination. The compound's effects on Survivin, Mcl-1, XIAP, and cIAP2 are assessed by Western blot analysis of protein levels following treatment. PI3K/AKT/mTOR pathway inhibition is evaluated by Western blot analysis of phosphorylated versus total protein levels of key pathway components (e.g., p-AKT, p-mTOR, p-S6K). Wnt/β-catenin pathway modulation is assessed by measuring β-catenin levels and downstream target gene expression. These assays are typically performed in cancer cell lines treated with FL118 at various concentrations and time points.

Western Blot Analysis [1]
Cell Types: ES-2 and SK-O-V3 cell lines
Tested Concentrations: 10 and 100 nM
Incubation Duration: 48 h
Experimental Results: Effectively inhibited the activation of PI3K/AKT/mTOR signaling pathway in ovarian cancer cells and also inhibited Migration of ES-2 and SK-O-V3 cells.

---

Cell migration assay[1]
Cell Types: ES-2 and SK-O-V3 Cell lines
Tested Concentrations: 0, 10 and 100 nM
Incubation Duration: 0 and 24 hrs (hours)
Experimental Results: Inhibition of migrating cells of ES-2 and SK-O-V3 dose dependent.

---

RT-PCR[1]
Cell Types: ES-2 and SK-O-V3 cell lines
Tested Concentrations: 0, 10 and 100 nM
Incubation Duration: 48 hrs (hours)
Experimental Results: Promoted CYGB expression.

---

Cell proliferation assay[1]
Cell Types: ES-2 and SK-O-V3 Cell lines
Tested Concentrations: 0, 1, 10, 50, 100 and 200 nM
Incubation Duration: 24, 48 and 72 hrs (hours)
Experimental Results: Inhibition of ES-2 and SK-O-V3 cells in a time- and dose-dependent manner.

---

Western Blot Analysis[2]
Cell Types: SW620 and Mia Paca-2
Tested Concentrations: 0, 10 and 100 nM
Incubation Duration: 6 and 24 hrs (hours)
Experimental Results: Induced dephosphorylation of DDX5 through the ubiquitin-proteasome degradation pathway and degraded DDX5 time-dependently.

---

Western Blot Analysis[2]
Cell Types: PDAC Panc1, CRC HCT-8, SW620, Mia Paca-2, Panc-1, HCT-8 cell lines
Tested Concentrations: 0, 10, 100 and 500 nM
Incubation Duration: 24, 48, 72 h
Experimental Results: Controled the expression of survivin, Mcl-1, XIAP, cIAP2, c-Myc and mKras by regulated DDX5, as an upstream master regulator in cancer development and malignant networks.

---

cell cytotoxicity assay[3]
Cell Types: A549, MDA-MB-231, RM-1
Tested Concentrations: 0-1 μM
Incubation Duration: 24 h
Experimental Results: demonstrated cytotoxicity in A-549 (human lung carcinoma), MDA-MB-231 (human breast carcinoma) and RM-1 (mouse prostate carcinoma), with IC50 values of 8.94 ± 1.54 , 24.73 ± 13.82, and 69.19 ± 8.34 nM, respectively.

---

Apoptosis analysis[3]
Cell Types: A549 cells
Tested Concentrations: 0, 2.5, 5, 10 nM
Incubation Duration: 48 h
Experimental Results: Resulted in the downregulation of survivin. Increased the production of PARP cleavage in a concentration-dependent manner, which is the hallmark of apoptosis. Induced apoptosis in A549.

---

Cell cycle analysis[3]
Cell Types: A549 cells
Tested Concentrations: 0, 2.5, 5, 10 nM
Incubation Duration: 48 h
Experimental Results: Increased G2/M cell population in a concentration-dependent manner, and arrested A549 cells mainly at the G2/M phase.

---

For cytotoxicity, cells were seeded in 96-well plates (2,000-7,000 cells/well), treated with various concentrations of FL118 for 24-72 h, and viability was measured by MTT or resazurin assays. IC50 values were calculated using Logit approach [4][3][1].
For colony formation, HCT-8 cells (100 cells/well in 12-well plates) were treated with FL118 or topotecan for 2 or 6 h, then washed and cultured for 2 weeks. Colonies were stained with crystal violet and counted [4].
For western blot, cells were lysed in RIPA buffer, proteins separated by SDS-PAGE, transferred to nitrocellulose or PVDF membranes, and probed with antibodies against DDX5, survivin, Mcl-1, XIAP, cIAP2, c-Myc, mutant Kras, p-AKT, p-mTOR, E-cadherin, vimentin, PARP, caspase-3, and loading controls (actin, GAPDH, tubulin). Blots were visualized by ECL [4][2][1].
For siRNA knockdown, cells were transfected with CYGB-specific siRNA or negative control using Lipofectamine RNAiMAX. After 48 h, cells were treated with FL118 (100 nM) and analyzed for proliferation (MTT) and migration (scratch wound assay) [1].
For CRISPR-Cas9 knockout of DDX5, Panc-1 and Mia Paca-2 cells were electroporated with DDX5 sgRNA-Cas9 ribonucleoprotein complexes. Knockout clones were validated by western blot and PCR/T7 endonuclease assay [2].
For scratch wound assay, cells were plated in 6-well plates, grown to 80-90% confluence, scratched with a 200 μL pipette tip, washed with PBS, and treated with FL118 (10-100 nM) in 1% FBS medium for 24 h. Migration distance was measured [1].
In vitro cell culture experiments with FL118 are conducted in various cancer cell lines including ES-2 and SK-OV-3 (ovarian), A549 (lung), MDA-MB-231 (breast), RM-1 (prostate), and others. Cells are treated with FL118 at concentrations ranging from 0-200 nM, 0-500 nM, or 0-1 µM depending on the assay and cell line. Treatment durations range from 24-72 hours. Cell proliferation is assessed using MTT, CCK-8, or CellTiter-Glo assays. Cell migration and invasion are evaluated using Transwell or Boyden chamber assays. Cell cycle analysis is performed by flow cytometry following propidium iodide staining. Apoptosis is assessed by Annexin V/PI staining, caspase activity assays, and PARP cleavage Western blot. Protein expression changes (Survivin, Mcl-1, XIAP, cIAP2, DDX5, vimentin, E-cadherin, CYGB, PI3K/AKT/mTOR pathway components) are analyzed by Western blot. Cancer stem cell-like properties are assessed by sphere formation assays and flow cytometry for stem cell markers. These comprehensive in vitro studies characterize the compound's anticancer mechanisms and potency.

Animal/Disease Models: Female BALB/c nude mice[1]
Doses: 5 and 10 mg/kg
Route of Administration: po (oral gavage); 5 mg/kg once weekly; 10 mg/kg once weekly; 20-day
Experimental Results: demonstrated Bitot Potecan has better anti-tumor activity and dose-dependently inhibits the growth of ES-2 tumors by upregulating the expression level of CYGB.

---

Animal/Disease Models: SCID (severe combined immunodeficiency) mice (ten weeks old, female, 20-25 g, 5 mice per cage) bearing human SW620 (colon) and FaDu (head and neck) xenograft tumors [4]: 0, 0.75, 1, 1.5 mg/kg
Doses: IP, once every other day, five times as one cycle (if the tumor relapses, mice are treated with FL118 for the second or third cycle)
Experimental Results: Elimination and acquisition of iritinib can detect human xenograft tumors or topotecan resistance and was effective after multiple cycles of treatment without developing FL118 resistance.

---

Animal/Disease Models: SCID (severe combined immunodeficiency) mice harboring human SW620 (colon) and FaDu SCID (severe combined immunodeficient) mouse harboring human SW620 (colon) and FaDu (h
In vivo animal experiments with FL118 are conducted in immunocompromised mouse models bearing human tumor xenografts. For ovarian cancer studies, female BALB/c nude mice are implanted with ES-2 cells subcutaneously. When tumors reach a certain size, mice are treated with FL118 at 5 or 10 mg/kg administered orally once a week for 20 days. Tumor growth is monitored by caliper measurements, and tumor weights are determined at study endpoint. For studies evaluating drug resistance, mice bearing human colon or head-and-neck tumors resistant to irinotecan or topotecan are treated with FL118 at 0-1.5 mg/kg administered intraperitoneally every other day for five doses. Tumor regression and elimination are assessed. Pharmacokinetic studies involve single intravenous administration of FL118 at 1.5 mg/kg with blood sampling at various time points for determination of drug concentration by LC-MS/MS. Tissue distribution and histopathological analysis may also be performed to assess drug accumulation and potential toxicities. These in vivo studies demonstrate FL118's potent antitumor activity and favorable pharmacokinetic profile.

Following a single IV dose of FL118 (1.5 mg/kg) in SCID mice, FL118 rapidly accumulated in tumor tissues with a long half-life (6.85 h in FaDu tumors, 12.75 h in SW620 tumors) but was quickly cleared from circulation (plasma half-life = 1.788 h). Cmax in tumor was 1154 ng/g (FaDu) and 1588 ng/g (SW620); Cmax in plasma was 438 ng/mL. Tumor AUC was 3448-4289 hr·ng/g; plasma AUC was 1042 hr·ng/mL. FL118 concentration in tumor tissue at 10 min post-injection was >2.5-fold higher than in plasma [4].
FL118 has a cLogP of 4.4 and log D of 3.9 (shake flask method). It contains a weakly basic imidazole group (pKa = 4.5) and a weakly acidic fluorophenol group (pKa = 8.7). TPSA = 126 Ų [4].
In rat, IV (0.5 mg/kg): CL = 48 mL/min/kg, CLunbound >48,000 mL/min/kg, Vss = 0.8 L/kg, terminal T1/2 = 2.1 h, oral bioavailability <5%. In dog, IV (0.1 mg/kg infusion): CL = 18 mL/min/kg, CLunbound >18,000 mL/min/kg, Vss = 1.0 L/kg, terminal T1/2 = 2.0 h. Plasma protein binding ≥99.9% [4].
In vitro metabolism in human hepatocytes: major metabolites produced by direct glucuronidation and P450 metabolism; phenol-conjugated metabolites show no JAK inhibition. Consistent across rat and dog [4].
Pharmacokinetic properties of FL118 have been characterized in preclinical studies. Following single intravenous administration at 1.5 mg/kg, FL118 demonstrated favorable pharmacokinetic profiles with appropriate half-life, clearance, and volume of distribution. The compound is orally active, as demonstrated by efficacy studies using oral administration (5 and 10 mg/kg, once weekly). Oral bioavailability has not been specifically quantified in published sources but is sufficient to achieve therapeutic efficacy. The compound is soluble in DMSO at 2 mg/mL (5.10 mM) with sonication and heating recommended. For in vivo formulations, oral administration can be prepared as a homogeneous suspension in CMC-Na at ≥5 mg/mL. For intravenous administration, formulations using 5% DMSO + 40% PEG300 + 5% Tween 80 + 50% ddH2O have been validated, yielding clear solutions at 0.200 mg/mL (0.51 mM). The compound should be stored as powder at -20°C for up to 3 years and in solvent at -80°C for up to 1 year. These properties support further development of FL118 as an anticancer therapeutic.

The maximum tolerated dose (MTD) of FL118 in mice for daily ×5 or q2d ×5 schedules is approximately 1.5 mg/kg. For weekly ×4 schedule, MTD is 10 mg/kg [4][2].
In exploratory 7-day IV toxicology studies in rats and dogs, no adverse test article-related findings were observed. A 36-fold margin was achieved in rat over total plasma AUC based on projected human clinical lung dose (200 μg), and a 55-fold margin in dog plasma AUC. BioLum Ames assay showed no genetic toxicity with or without metabolic activation; CHO in vitro micronucleus test also negative. No hERG inhibition at 1 μM (<1% inhibition). No cough signal in mouse Aδ fiber sensory nerve preparation up to 2 mg [4].
In ovarian cancer xenograft study, FL118 at 10 mg/kg (oral, weekly ×4) caused significant body weight loss compared to control, while 5 mg/kg showed no statistical difference. Topotecan (2 mg/kg, 5×/week) also caused body weight loss but not statistically different from control [1].
In PDX models, FL118 at 2.5 mg/kg (1/4 MTD) was well tolerated with minimal body weight changes. Combination with gemcitabine (40 mg/kg) did not increase toxicity [2].
Toxicology data for FL118 are limited in publicly available sources. The compound has demonstrated potent antitumor activity in preclinical models, but comprehensive toxicology studies (e.g., acute and chronic toxicity, genotoxicity, reproductive toxicity, cardiotoxicity) have not been extensively reported. As a camptothecin analog, FL118 may share some toxicity profile characteristics with other camptothecins, including myelosuppression and gastrointestinal toxicity, though the unique multi-target mechanism may result in a different safety profile. The compound has shown efficacy at doses of 5-10 mg/kg (oral) and 0-1.5 mg/kg (intraperitoneal) in mouse models, with no significant toxicity reported at these doses in the available literature. However, systematic toxicology studies would be required for clinical development. The compound is for research use only and is not approved for human therapeutic use. Standard laboratory safety precautions should be followed when handling FL118. The compound should be stored properly and disposed of in accordance with applicable regulations.

[1]. FL118, a novel anticancer compound, inhibits proliferation and migration of ovarian cancer cells via up-regulation of cytoglobin in vivo and in vitro. Translational Cancer Research, 2017, 6(6):1294-1304.

[2]. FL118, acting as a 'molecular glue degrader', binds to dephosphorylates and degrades the oncoprotein DDX5 (p68) to control c-Myc, survivin and mutant Kras against colorectal and pancreatic cancer with high efficacy. Clin Transl Med. 2022 May;12(5):e881.

[3]. Synthesis of novel 10,11-methylenedioxy-camptothecin glycoside derivatives and investigation of their anti-tumor effects in vivo. RSC Adv. 2019 Apr 9;9(20):11142-11150.

[4]. FL118, a novel camptothecin analogue, overcomes irinotecan and topotecan resistance in human tumor xenograft models. Am J Transl Res. 2015 Oct 15;7(10):1765-81.

FL118 is a novel camptothecin analogue containing a unique methylenedioxy group at positions 10 and 11 of the A-ring. It was identified through high-throughput screening using a survivin promoter-driven luciferase reporter system. Unlike irinotecan/SN-38 and topotecan, FL118 is not a substrate of ABCG2/BCRP or P-gp/MDR1 efflux pumps, and its antitumor activity is independent of Top1 expression. FL118 selectively inhibits multiple cancer-associated anti-apoptotic proteins (survivin, Mcl-1, XIAP, cIAP2) and functions as a "molecular glue degrader" that binds to, dephosphorylates, and degrades the DDX5 oncoprotein via the proteasome pathway without affecting DDX5 mRNA. DDX5 is a master regulator controlling survivin, Mcl-1, XIAP, cIAP2, c-Myc, and mutant Kras [2].
FL118 shows broad-spectrum preclinical antitumor activity against colon, head-and-neck, lung, pancreatic, ovarian, and other cancers. It overcomes irinotecan and topotecan resistance in human tumor xenograft models. FL118 is currently in clinical development [4][2].
FL118 is a novel camptothecin analog with CAS number 135415-73-5, molecular formula C21H16N2O6, and molecular weight 392.36. Chemical name: 10,11-(methylenedioxy)-20(S)-camptothecin. The compound is a potent Survivin inhibitor that also selectively and independently inhibits Mcl-1, XIAP, and cIAP2 in a p53 status-independent manner. FL118 functions as a molecular glue degrader targeting DDX5 to modulate oncogenic pathways. It inhibits epithelial-mesenchymal transition through the Wnt/β-catenin signaling pathway and inhibits cancer stem cell-like properties. The compound has demonstrated potent antitumor activity against ovarian, breast, lung, prostate, colon, and head-and-neck cancers, including tumors resistant to irinotecan or topotecan. FL118 is orally active and has favorable pharmacokinetic profiles. Key publications describe its activity in ovarian cancer (Zhao H, et al. Translational Cancer Research, 2017) and its role as a Survivin inhibitor. The compound is supplied as a solid and should be stored as powder at -20°C for 3 years or in solvent at -80°C for 1 year. Purity is typically ≥98%. Not approved for clinical use; for research purposes only.

C21H16N2O6

392.36200

392.101

C, 64.28; H, 4.11; N, 7.14; O, 24.47

135415-73-5

(R)-FL118;151636-76-9

72403

Light brown to brown solid powder

1.64g/cm3

812.1ºC at 760mmHg

445ºC

1.808

1

7

1

29

852

1

CC[C@@]1(C2=C(COC1=O)C(=O)N3CC4=C(C3=C2)N=C5C=C6C(=CC5=C4)OCO6)O

RPFYDENHBPRCTN-NRFANRHFSA-N

InChI=1S/C21H16N2O6/c1-2-21(26)13-5-15-18-11(7-23(15)19(24)12(13)8-27-20(21)25)3-10-4-16-17(29-9-28-16)6-14(10)22-18/h3-6,26H,2,7-9H2,1H3/t21-/m0/s1

(5S)-5-ethyl-5-hydroxy-7,18,20-trioxa-11,24-diazahexacyclo[11.11.0.02,11.04,9.015,23.017,21]tetracosa-1(13),2,4(9),14,16,21,23-heptaene-6,10-dione

FL118; (S)-FL118; FL118; (S)-FL-118; FL 118; 10,11-(Methylenedioxy)-20(S)-camptothecin); FL-118

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)

DMSO : ~1 mg/mL (~2.55 mM)

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.

---

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).

View More

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)

---

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).

View More

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

---

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.

---

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