p110α (IC50 = 3 nM); p110β (IC50 = 33 nM); p110δ (IC50 = 3 nM); p110γ (IC50 = 75 nM); p110α-H1047R (IC50 = 3 nM); p110α-E545K (IC50 = 3 nM); DNA-PK (IC50 = 1.23 μM); mTOR (Ki = 0.58 μM); Autophagy

GDC-0941 is equipotent against PI3Kα and PI3Kδ as well as PI3Kα mutants E545-K and H1047-R, displaying modest levels of selectivity against PI3Kβ (10-fold) and PI3Kγ (25-fold), and greater levels of selectivity against members of PI3K class II, III, and IV, including C2β, Vps34, DNA-PK, and mTOR. With IC50 values of 46 nM, 37 nM, and 28 nM, respectively.[1] With an IC50 of 149-944 nM, GDC-0941 treatment effectively reduces the proliferation of HER2-amplified cells that are both trastuzumab-sensitive and -insensitive. With an IC50 of 500 nM or less, GDC-0941 effectively inhibits the proliferation of HER2-amplified cells that have PIK3CA mutations and the viability of HER2-amplified breast cancer cells that lack PTEN and are resistant to trastuzumab.[2] The growth of HCT116, DLD1, and HT29 cells is significantly inhibited by GDC-0941, with GI50 values of 1081 nM, 1070 nM, and 157 nM, respectively. [3] GDC-0941 suppresses the population of centroblasts, induces apoptosis, and inhibits the proliferation of tumor cells.[4]

GDC-0941 has a 78% oral bioavailability due to limited microsomal metabolism [5]. In established human U87MG glioblastoma xenografts in female NCr athymic mice, administration of GDC-0941 at 75 mg/kg/day results in a significant inhibitory effect, with tumor growth inhibition of 83%. [1] In mice with HER2-amplified, trastuzumab-resistant MDA-MB-361.1 xenografts, oral administration of GDC-0941 at 150 mg/kg/day significantly slows tumor progression and induces potent tumor apoptosis. [2] Two weeks of treatment with GDC-0941 (75 mg/kg/day) results in a 40% reduction in the tumor size of spontaneous B-cell follicular lymphomas in PTEN+/-LKB1+/hypo mice. This tumor volume reduction is accompanied by the elimination of Akt, S6K, and SGK (serum and glucocorticoid protein kinase) protein phosphorylation.[4]

Scintillation proximity assay; Recombinant human PI3Kα, PI3Kβ, and PI3Kδ are coexpressed in a Sf9 baculovirus system with the p85α regulatory subunit and are purified as GST-fusion proteins using affinity chromatography on glutathione-sepharose. Scintillation proximity assay. Recombinant human PI3Kγ is similarly expressed and purified as monomeric GST-fusions. GDC-0941 is dissolved in DMSO and infused into a 50 μL mixture of 20 mM Tris-HCl (pH 7.5), 4 mM MgCl2, 1 mM DTT, 1 μM ATP, 0.125 μCi [γ-33P]-ATP, and 4% (v/v) DMSO. To start the kinase reaction, the assay mixture is mixed with the recombinant GST-fusion of PI3Kα (5 ng), PI3Kβ (5 ng), PI3Kδ (5 ng), or PI3Kγ (5 ng).

BT474-M1, SKBR-3, AU-565, HCC-1419, ZR75-30, JIMT-1, BT474-EEI, HCC-1954, MCF-7, CALU-3, SKOV-3, and MKN-7 cells are exposed to different concentrations of GDC-0941 for 48 and 72 hours. The CellTiter-Glo Luminescent Cell Viability Assay is used to identify cell viability and proliferation. By using a western blot, the pAkt (Ser473), cleaved caspase-3, and cleaved PARP are all examined. Apoptosis and caspase 3/7 activity are both detected using the Cell Death Detection ELISAplus assay and the Caspase-Glo 3/7 assay, respectively.

Under the skin, MCF7-neo/HER2 or MX-1 breast cancer cells are injected into female nu/nu mice. Animals are distributed into groups of 10 animals each when tumors reach a mean volume of 200 to 250 mm3. Group sizes are determined by size matching. Once a week, intravenous RP-56976, a formulation of 3% EtOH and 97% saline, is given. Pictilisib (GDC-0941), a daily oral dose of MCT (0.5% methylcellulose, 0.2% Tween-80), is administered. By directly implanting tumors from patients under the skin of NMRI nu/nu mice, the MAXF1162 HER2+/ER+/PR+ patient-derived breast cancer tumor xenograft model was created. Volume of the tumor is calculated. Throughout a study, tumor size measurements are taken twice a week.

Pharmacokinetics [6]
Pharmacokinetic parameters of pictilisib were estimated for all dose cohorts and are summarized in Table 3 and Supplementary Table 1. Under fasting conditions, pictilisib was rapidly absorbed after oral administration (median Tmax of 2 hours [range 0.5-8]); this was independent of dose and was unchanged after multiple doses. Terminal plasma elimination half-life (T1/2) on day 1 ranged between 13.1 and 24.1 hours. Dose-proportional increases in exposure (Cmax and AUC0-24) was observed across the dose levels studied (Figure 1). Similar pharmacokinetic characteristics were seen on day 15. The accumulation index (AUCDay15/AUCDay1) ranged from 1.2 to 2.2, suggesting modest accumulation following multiple doses.

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The absorption, metabolism and excretion of pictilisib, a selective small molecule inhibitor of class 1 A phosphoinositide 3-kinase (PI3K), was characterized following a single oral administration of [14C]pictilisib in rats, dogs and humans at the target doses of 30 mg/kg, 5 mg/kg and 60 mg, respectively.Pictilisib was rapidly absorbed with Tmax less than 2 h across species. In systemic circulation, pictilisib represented the predominant total radioactivity greater than 86.6% in all species.Total pictilisib and related radioactivity was recovered from urine and faeces in rats, dogs, and human at 98%, 80% and 95%, respectively, with less than 2% excreted in urine and the rest excreted into faeces.In rat and dog, more than 40% of drug-related radioactivity was excreted into the bile suggesting biliary excretion was the major route of excretion. Unchanged pictilisib was a minor component in rat and dog bile. The major metabolite in bile was O-glucuronide of oxidation on indazole moiety (M20, 21% of the dose) in rats and an oxidative piperazinyl ring-opened metabolite M7 (10.8% of the dose) in dogs.Oxidative glutathione (GSH) conjugates (M18, M19) were novel metabolites detected in rat bile, suggesting the potential generation of reactive intermediates from pictilisib. The structure of M18 was further confirmed by NMR to be a N-hydroxylated and GSH conjugated metabolite on the moiety of the indazole ring. Xenobiotica . 2021 Jul;51(7):796-810. https://pubmed.ncbi.nlm.nih.gov/33938357/

Safety and tolerability [6]
Pictilisib was well-tolerated up to 330mg (21/28 schedule); most adverse events were mild to moderate in severity with no treatment-related deaths (Table 2). At the assessed dose levels, there did not appear to be a significant difference in the toxicity profile between the 21/28 and 28/28 schedules. Treatment-related adverse events that occurred in ≥10% of patients included: nausea, diarrhea, vomiting, fatigue, dysgeusia, decreased appetite and rash. In addition to the 2 DLTs of grade 3 rash at the 450mg dose level, the third patient at this dose level experienced grade 2 rash; nonetheless, this patient received 8 months of pictilisib with concomitant use of oral antihistamines and skin emollients. Of 10 patients treated with 330mg once-daily(28/28 schedule), grade 1 or 2 rash was observed in 2 patients, and grade 3 rash (occurring after the DLT-defining window) in 2 patients; these similarly resolved with the introduction of drug holidays and supportive medications including emollients and corticosteroids. [6]
Other clinically-relevant drug-related adverse events ≥grade 3 were grade 4 hyperglycemia (n=1, 130mg) and grade 3 pneumonitis (n=1, 340mg). The grade 4 hyperglycemia was transient, unaccompanied by clinically significant symptoms, signs or acidosis, and occurred in a patient with cholangiocarcinoma and previous pancreatico-duodenectomy who started the use of low-dose prednisolone 2 days prior to the event. Grade 3 pneumonitis was observed at the end of cycle 1 in a breast cancer patient previously treated with chest radiotherapy who developed grade 1 dyspnea, reduced DLCO and a ground glass appearance on HRCT; these resolved following 2 weeks of drug interruption and concomitant use of prednisolone. When pictilisib was reintroduced at 240mg, the dyspnea and HRCT changes recurred; these subsequently resolved following permanent discontinuation of pictilisib due to disease progression.

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DLTs and MTD [6]
The MTD was exceeded at 450mg once-daily (21/28 schedule) with a DLT of grade 3 rash in 2 patients. This was a maculopapular rash covering 70-80% of the body surface area that presented approximately 2 weeks after commencement of daily pictilisib dosing and resolved spontaneously 2 weeks after treatment discontinuation. At 330mg once-daily (21/28 schedule), the grade 3 maculopapular rash observed in 1 of 7 patients had a similar temporal pattern of onset and resolution; this was also declared as a DLT. On the 28/28 schedule, no DLT was observed.

[1] J Med Chem. 2008 Sep 25;51(18):5522-32.

[2]. Cancer Cell. 2009 May 5;15(5):429-40.

[3]. Br J Cancer. 2012 Apr 10;106(8):1386-94.

[4]. Br J Cancer. 2011 Mar 29;104(7):1116-25.

[5]. Mol Cancer Ther. 2009 Jul;8(7):1725-38.

[6]. Clin Cancer Res. 2015 Jan 1;21(1):77-86.

Pictilisib Bismesylate is the orally bioavailable bismesylate salt of pictilisib, a small molecule inhibitor of class I phosphatidylinositol 3 kinase (PI3K), with potential antineoplastic activity. Upon administration, pictilisib selectively binds to PI3K in an ATP-competitive manner, inhibiting the production of the secondary messenger phosphatidylinositol-3,4,5-trisphosphate (PIP3) and activation of the PI3K/Akt signaling pathway. This may result in inhibition of tumor cell growth, motility and survival in susceptible tumor cell populations. Activation of the PI3K/Akt signaling pathway is frequently associated with tumorigenesis; dysregulated PI3K/Akt signaling may contribute to tumor resistance to a variety of antineoplastic agents.

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Phosphatidylinositol-3-kinase (PI3K) is an important target in cancer due to the deregulation of the PI3K/ Akt signaling pathway in a wide variety of tumors. A series of thieno[3,2-d]pyrimidine derivatives were prepared and evaluated as inhibitors of PI3 kinase p110alpha. The synthesis, biological activity, and further profiling of these compounds are described. This work resulted in the discovery of 17, GDC-0941, which is a potent, selective, orally bioavailable inhibitor of PI3K and is currently being evaluated in human clinical trials for the treatment of cancer.[1]

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Herceptin (trastuzumab) is the backbone of HER2-directed breast cancer therapy and benefits patients in both the adjuvant and metastatic settings. Here, we describe a mechanism of action for trastuzumab whereby antibody treatment disrupts ligand-independent HER2/HER3 interactions in HER2-amplified cells. The kinetics of dissociation parallels HER3 dephosphorylation and uncoupling from PI3K activity, leading to downregulation of proximal and distal AKT signaling, and correlates with the antiproliferative effects of trastuzumab. A selective and potent PI3K inhibitor, GDC-0941, is highly efficacious both in combination with trastuzumab and in the treatment of trastuzumab-resistant cells and tumors.[2]

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Background: Combined targeting of MAPK and PI3K signalling pathways may be necessary for optimal therapeutic activity in cancer. This study evaluated the MEK inhibitors AZD6244 and PD0325901, alone and in combination with the dual mTOR/PI3K inhibitor NVP-BEZ235 or the PI3K inhibitor GDC-0941, in three colorectal cancer cell lines. Methods: Growth inhibition, survival and signal transduction were measured using the Sulforhodamine B assay, clonogenicity and western blotting, respectively, in HCT116, HT29 and DLD1 cell lines. Results: All MEK/PI3K inhibitor combinations exhibited marked synergistic growth inhibition; however, GDC-0941 displayed greater synergy in combination with either MEK inhibitor. NVP-BEZ235 exhibited stronger inhibition of 4EBP1 phosphorylation, and similar inhibition of S6 and AKT phosphorylation, compared with GDC-0941. Both PD0325901 and AZD6244 inhibited ERK phosphorylation, and with MEK/PI3K inhibitor combinations inhibition of S6 phosphorylation was increased. The reduced synergy exhibited by NVP-BEZ235 in combination with MEK inhibitors, compared with GDC-0941, may be due to inhibition of mTOR, and the addition of the mTORC1/2 inhibitor KU0063794 compromised the synergy of GDC-0941:PD0325901 combinations. Conclusion: These studies confirm that dual targeting of PI3K and MEK can induce synergistic growth inhibition; however, the combination of specific PI3K inhibitors, rather than dual mTOR/PI3K inhibitors, with MEK inhibitors results in greater synergy.[3]

C25H35N7O9S4

705.84

705.137

C, 42.54; H, 5.00; N, 13.89; O, 20.40; S, 18.17

957054-33-0

Pictilisib;957054-30-7

56972143

White to light yellow solid powder

>280°C (dec.)

3

16

5

45

924

0

O=S(C)(O)=O.O=S(C)(N1CCN(CC2=CC3N=C(C4C5=C(NN=C5)C=CC=4)N=C(C=3S2)N2CCOCC2)CC1)=O

RFRIKACSFOTIMU-UHFFFAOYSA-N

InChI=1S/C23H27N7O3S2.2CH4O3S/c1-35(31,32)30-7-5-28(6-8-30)15-16-13-20-21(34-16)23(29-9-11-33-12-10-29)26-22(25-20)17-3-2-4-19-18(17)14-24-27-19;2*1-5(2,3)4/h2-4,13-14H,5-12,15H2,1H3,(H,24,27);2*1H3,(H,2,3,4)

4-[2-(1H-indazol-4-yl)-6-[(4-methylsulfonylpiperazin-1-yl)methyl]thieno[3,2-d]pyrimidin-4-yl]morpholine;methanesulfonic acid

2934.99.9001

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.

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