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Supplementary Figures 1-4 from Preclinical Pharmacology, Antitumor Activity, and Development of Pharmacodynamic Markers for the Novel, Potent AKT Inhibitor CCT128930

Supplementary Figure Legends and Supplementary Table 1 from Preclinical Pharmacology, Antitumor Activity, and Development of Pharmacodynamic Markers for the Novel, Potent AKT Inhibitor CCT128930

Supplementary Table from Individualized Prediction of Drug Response and Rational Combination Therapy in NSCLC Using Artificial Intelligence–Enabled Studies of Acute Phosphoproteomic Changes

AKT is frequently deregulated in cancer, making it an attractive anticancer drug target. CCT128930 is a novel ATP-competitive AKT inhibitor discovered using fragment- and structure-based approaches. It is a potent, advanced lead pyrrolopyrimidine compound exhibiting selectivity for AKT over PKA, achieved by targeting a single amino acid difference. CCT128930 exhibited marked antiproliferative activity and inhibited the phosphorylation of a range of AKT substrates in multiple tumor cell lines in vitro, consistent with AKT inhibition. CCT128930 caused a G1 arrest in PTEN-null U87MG human glioblastoma cells, consistent with AKT pathway blockade. Pharmacokinetic studies established that potentially active concentrations of CCT128930 could be achieved in human tumor xenografts. Furthermore, CCT128930 also blocked the phosphorylation of several downstream AKT biomarkers in U87MG tumor xenografts, indicating AKT inhibition in vivo. Antitumor activity was observed with CCT128930 in U87MG and HER2-positive, PIK3CA-mutant BT474 human breast cancer xenografts, consistent with its pharmacokinetic and pharmacodynamic properties. A quantitative immunofluorescence assay to measure the phosphorylation and total protein expression of the AKT substrate PRAS40 in hair follicles is presented. Significant decreases in pThr246 PRAS40 occurred in CCT128930-treated mouse whisker follicles in vivo and human hair follicles treated ex vivo, with minimal changes in total PRAS40. In conclusion, CCT128930 is a novel, selective, and potent AKT inhibitor that blocks AKT activity in vitro and in vivo and induces marked antitumor responses. We have also developed a novel biomarker assay for the inhibition of AKT in human hair follicles, which is currently being used in clinical trials. Mol Cancer Ther; 10(2); 360–71. ©2010 AACR.

We hypothesize that the study of acute protein perturbation in signal transduction by targeted anticancer drugs can predict drug sensitivity of these agents used as single agents and rational combination therapy. We assayed dynamic changes in 52 phosphoproteins caused by an acute exposure (1 hour) to clinically relevant concentrations of seven targeted anticancer drugs in 35 non–small cell lung cancer (NSCLC) cell lines and 16 samples of NSCLC cells isolated from pleural effusions. We studied drug sensitivities across 35 cell lines and synergy of combinations of all drugs in six cell lines (252 combinations). We developed orthogonal machine-learning approaches to predict drug response and rational combination therapy. Our methods predicted the most and least sensitive quartiles of drug sensitivity with an AUC of 0.79 and 0.78, respectively, whereas predictions based on mutations in three genes commonly known to predict response to the drug studied, for example, EGFR, PIK3CA, and KRAS, did not predict sensitivity (AUC of 0.5 across all quartiles). The machine-learning predictions of combinations that were compared with experimentally generated data showed a bias to the highest quartile of Bliss synergy scores (P = 0.0243). We confirmed feasibility of running such assays on 16 patient samples of freshly isolated NSCLC cells from pleural effusions. We have provided proof of concept for novel methods of using acute ex vivo exposure of cancer cells to targeted anticancer drugs to predict response as single agents or combinations. These approaches could complement current approaches using gene mutations/amplifications/rearrangements as biomarkers and demonstrate the utility of proteomics data to inform treatment selection in the clinic.

Purpose We hypothesised that plasticity in signal transduction may be a mechanism of drug resistance and tested this hypothesis in the setting of cetuximab resistance in patients with KRAS/NRAS/BRAFV600 wild-type colorectal cancer (CRC). Methods A multiplex antibody-based platform was used to study simultaneous changes in signal transduction of 55 phospho-proteins in 12 KRAS/NRAS/BRAFV600 wild-type CRC cell lines (6 cetuximab sensitive versus 6 cetuximab resistant) following 1 and 4 h in vitro cetuximab exposure. We validated our results in CRC patient samples (n = 4) using ex vivo exposure to cetuximab in KRAS/NRAS/BRAFV600 cells that were immunomagnetically separated from the serous effusions of patients with known cetuximab resistance. Results Differences in levels of phospho-proteins in cetuximab sensitive and resistant cell lines included reductions in phospho-RPS6 and phospho-PRAS40 in cetuximab sensitive, but not cetuximab resistant cell lines at 1 and 4 h, respectively. In addition, phospho-AKT levels were found to be elevated in 3/4 patient samples following ex vivo incubation with cetuximab for 1 h. We further explored these findings by studying the effects of combinations of cetuximab and two PI3K pathway inhibitors in 3 cetuximab resistant cell lines. The addition of PI3K pathway inhibitors to cetuximab led to a significantly higher reduction in colony formation capacity compared to cetuximab alone. Conclusion Our findings suggest activation of the PI3K pathway as a mechanism of cetuximab resistance in KRAS/NRAS/BRAFV600 wild-type CRC.

Purpose We hypothesised that plasticity in signal transduction may be a mechanism of drug resistance and tested this hypothesis in the setting of cetuximab resistance in patients with KRAS/NRAS/BRAFV600 wild-type colorectal cancer (CRC). Methods A multiplex antibody-based platform was used to study simultaneous changes in signal transduction of 55 phospho-proteins in 12 KRAS/NRAS/BRAFV600 wild-type CRC cell lines (6 cetuximab sensitive versus 6 cetuximab resistant) following 1 and 4 h in vitro cetuximab exposure. We validated our results in CRC patient samples (n = 4) using ex vivo exposure to cetuximab in KRAS/NRAS/BRAFV600 cells that were immunomagnetically separated from the serous effusions of patients with known cetuximab resistance. Results Differences in levels of phospho-proteins in cetuximab sensitive and resistant cell lines included reductions in phospho-RPS6 and phospho-PRAS40 in cetuximab sensitive, but not cetuximab resistant cell lines at 1 and 4 h, respectively. In addition, phospho-AKT levels were found to be elevated in 3/4 patient samples following ex vivo incubation with cetuximab for 1 h. We further explored these findings by studying the effects of combinations of cetuximab and two PI3K pathway inhibitors in 3 cetuximab resistant cell lines. The addition of PI3K pathway inhibitors to cetuximab led to a significantly higher reduction in colony formation capacity compared to cetuximab alone. Conclusion Our findings suggest activation of the PI3K pathway as a mechanism of cetuximab resistance in KRAS/NRAS/BRAFV600 wild-type CRC. Supplementary Information The online version contains supplementary material available at 10.1007/s13402-021-00628-7.

We hypothesize that the study of acute protein perturbation in signal transduction by targeted anticancer drugs can predict drug sensitivity of these agents used as single agents and rational combination therapy. We assayed dynamic changes in 52 phosphoproteins caused by an acute exposure (1 hour) to clinically relevant concentrations of seven targeted anticancer drugs in 35 non–small cell lung cancer (NSCLC) cell lines and 16 samples of NSCLC cells isolated from pleural effusions. We studied drug sensitivities across 35 cell lines and synergy of combinations of all drugs in six cell lines (252 combinations). We developed orthogonal machine-learning approaches to predict drug response and rational combination therapy. Our methods predicted the most and least sensitive quartiles of drug sensitivity with an AUC of 0.79 and 0.78, respectively, whereas predictions based on mutations in three genes commonly known to predict response to the drug studied, for example, EGFR, PIK3CA, and KRAS, did not predict sensitivity (AUC of 0.5 across all quartiles). The machine-learning predictions of combinations that were compared with experimentally generated data showed a bias to the highest quartile of Bliss synergy scores (P = 0.0243). We confirmed feasibility of running such assays on 16 patient samples of freshly isolated NSCLC cells from pleural effusions. We have provided proof of concept for novel methods of using acute ex vivo exposure of cancer cells to targeted anticancer drugs to predict response as single agents or combinations. These approaches could complement current approaches using gene mutations/amplifications/rearrangements as biomarkers and demonstrate the utility of proteomics data to inform treatment selection in the clinic.

Background: Low-grade serous ovarian cancer (LGSOC) constitutes up to 10% of all ovarian cancer and has clinical and molecular characteristics (resistance to chemotherapy, presence of RAS/RAF mutations, lack of TP53 mutations) distinct from high-grade serous ovarian cancer. Here, we characterized the effects of the dual RAF/MEK inhibitor VS-6766 and the FAK inhibitor defactinib on signal transduction and viability in LGSOC cell lines and patient-derived organoids. To correlate molecular characteristics with clinical response, we characterized genomic alterations in archival tumor samples from patients with LGSOC treated with the combination of VS-6766 and defactinib on a clinical trial (FRAME). Material and Methods: We exposed 5 LGSOC cell lines to clinical Cmax concentrations adjusted for protein binding of VS-6766 and defactinib. We quantified phospho- and total proteins (n=66) with an antibody-bead based assay normalized to GAPDH. We also studied growth inhibitory effects of the combination on KRAS mutant (mt) LGSOC patient-derived organoids. We performed next generation sequencing on archival samples from LGSOC patients treated with VS-6766 in combination with defactinib. Results: Signal transduction changes at 1 hr included reduction of p-FAK in 5/5 cell lines in response to defactinib. Cells exposed to VS-6766 showed a reduction in p-ERK and p-p90-RSK in 4/5 cell lines. Additionally, VS-6766 decreased p-cJUN and increased p-IκB in 4/5 cell lines, changes correlated with apoptosis. At 24 hrs, p-ERK and p-p90-RSK inhibition were maintained in 3/5 cell lines. Both drugs increased cleaved PARP in 4/5 cell lines and VS-6766 increased p-SMAD3 and BIM levels, indicating an increase in cell death/apoptosis. The combination of VS-6766 + defactinib showed synergistic growth inhibition in a KRAS mt LGSOC organoid model (combination index 0.51). The clinical combination of VS-6766 and defactinib (September 2021 cut-off) has shown an objective response rate (ORR) of 11/24 (46%) across all patients with LGSOC, and an ORR of 64% (7/11) for patients with KRAS mt LGSOC (n=11). In addition to mutations in KRAS, emerging data may suggest a correlation of U2AF1 and MED12 mutations with response. Conclusions: VS-6766, the dual RAF/MEK inhibitor, induces significant inhibition of ERK pathway signaling in addition to perturbations in TNF/NFκB signaling. Both defactinib and VS-6766 induce apoptosis in LGSOC models. The results provide mechanistic insights into the encouraging response rates observed in patients with LGSOC treated with VS-6766 and defactinib (NCT03875820). These data support the ongoing randomized phase II ENGOTov60/GOG3052/RAMP201 study (NCT04625270). Citation Format: Adam R. Stewart, Lisa Pickard, Ekta Paranjape, Victoria Sanchez Perez, Sanjib Chowdhury, Stephanie Lustgarten, Silvia Coma, Jonathan A. Pachter, Mark S. Carey, Gabriel DiMattia, Hannah C. Badham, Toby Prout, Mona Parmar, Muneeb Mahmud, Christina Yap, Matthew G. Krebs, Susana Banerjee, Udai Banerji. Mechanistic evaluation of VS-6766 (dual RAF/MEK inhibitor) and defactinib (FAK inhibitor) in low-grade serous ovarian cancer models with correlations to clinical response [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3476.

Background High-grade serous ovarian cancer (HGSOC) is characterized by extensive intratumoral heterogeneity, which is associated with drug resistance. Our aim was to study the effects of drugs used in the treatment of HGSOC - carboplatin (C), paclitaxel (P) and olaparib (O) - on clonal dynamics in experimental models. Methods We tracked clonal evolution in PEO1, a BRCA2-mutant HGSOC cell line model, by transfecting an initial population of 1.714x106 cells with a barcode (BC) library (CloneTrackerXP). Barcoded populations of cells (18.73x106 cells/flask) were grown in HYPERflasks till confluence, and then replicates were exposed to C (3163 nM) for 5 weeks, P (6.32 nM) for 4 weeks, and O (28467 nM) for 5 weeks (as single agents), reducing the cell population to < 10% (controls kept till cell confluence in the absence of drugs). After that, drug pressure was removed, allowing cells to regrow fully. NGS was used to quantify BCs in the final cell populations and, to get information on the temporal dynamics, also in dead floating cells collected from the weekly culture media change. Heterogeneity of the cell populations was estimated using the Shannon diversity index (SDI). Results The SDI in the controls was 6.306 (95% Bootstrap CI 6.304-6.310) for C and 6.192 (95% Bootstrap CI 6.190-6.197) for P and O. After exposure to C, P and O, the SDI was reduced to 3.208, 2.520 and 4.753 (95% Bootstrap CI 3.209-3.211, 2.517-2.523, 4.750-4.759) respectively, using aggregated replicates (pairwise 2-sided Hutcheson t-test: p < 2.2e-16 pre-drug exposure vs C, P and O). The number of unique BCs in controls vs C, P and O were 1799 vs 545, 1463 vs 288 and 1463 vs 1270, respectively, demonstrating reduction of heterogeneity and change in frequency of clones following drug selection pressure. Cell populations exposed to C and O share some similar clone selection (approximately 60%). This is important as, although the degree of heterogeneity caused by individual drugs are different (C and P lead to less heterogeneous populations than O), there is some concordance between the remaining clones determined by DNA damaging/DNA damage response inhibitors compared to clone selection following exposure to antimicrotubule agents. The selection pattern of BCs among replicates of the different drugs was similar with conservation of BCs with the highest fitness, demonstrating that the initial conditions are determinants of selection under drug exposure. Conclusion Our work, for the first time, quantifies and shows that heterogeneity followed by O therapy is greater than by C and P. Furthermore, the emergent population of cells post-selection pressure was more similar in the C and O groups when compared to P-exposed cells, suggesting correlation in the mechanism of action of drugs and drug resistance/tolerance. Our results also indicate that evolutionary dynamics are largely deterministic and, therefore, can be predictable. Citation Format: Alvaro H. Ingles Russo Garces, Salvatore Milite, Javier Fernandez-Mateos, Bingjie Chen, Lisa Pickard, Adam Stewart, Sara Diaz Sanchez, Rachel Lau, Erica Oliveira, Susana Banerjee, Andrea Sottoriva, Udai Banerji. A study of evolutionary dynamics induced by carboplatin, olaparib and paclitaxel in high-grade serous ovarian cancer cell line models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3790.

Purpose of study: CHK1 and WEE1 are critical determinants of the G2/M cell cycle checkpoint. The G2/M checkpoint is crucial to enable DNA repair caused by endogenous and exogenous stress. We hypothesised that simultaneous inhibition of CHK1 and WEE1 would cause cell death in TP53 mutated cell lines because of the associated replication stress due to an abrogated G1/S checkpoint. Experimental procedures: The potentiation index of the combination of SRA737 and adavosertib was calculated in six cancer cell lines harbouring TP53 mutations (OVCAR3, COV505, BT20, MDA-MB-436 and CAPAN1, MIAPaCa2) using Cell Titre Blue assays. Cell death and DNA damage was quantified using c-PARP, p-CHK1 Ser345 and gamma H2AX using western blot analysis. In-vivo studies evaluated the efficacy of vehicle control, SRA737, adavosertib and the combination in OVCAR3 and MDA-MB-436 xenograft models. We further explored the mechanisms of DNA damage repair caused by the single agents and the combination using two functional fluorescent multiplex DNA repair assay platforms in OVCAR3 and MDA-MB-436 cells; Exy-SPOT (base excision repair/nucleotide excision repair) and Next-SPOT (double strand break repair). Results: The potentiation index of the addition of SRA737 to adavosertib were 19, 8.6, 8.8, 9.7, 27.2 and 5.7 for COV504, OVCAR3, BT20, MDA-MB-436, CAPAN1 and MIAPaCa2 respectively. The combination of both drugs at single agent GI50 concentrations caused increase in c-PARP, p-CHK1 Ser345 and gamma H2AX in all cell lines studied. We chose to explore the combination in the TP53 mutated OVCAR3 and the TP53 and BRCA1 mutated MDA-MB-436 cell lines. In the OVCAR3 xenograft model, the combination of SRA737 and adavosertib caused tumour regressions and tumour volumes were significantly smaller than controls, p Conclusions: The combination of SRA737 and adavosertib caused cell death in TP53 mutated cell lines. There were differences in the DNA damage repair mechanisms in across cell lines and the combination showed significant activity in the xenograft models studied. The combination of SRA737 and adavosertib warrants further evaluation for the treatment of selected TP53 mutated cancers. Citation Format: Adam Stewart, Lisa Pickard, Albert E. Hallsworth, Sylvie Sauvaigo, Giovanna Muggiolu, Florence Raynaud, UDAI BANERJI. A study of combinatorial growth inhibition, cell death and DNA damage repair caused by CHK1 inhibitor SRA737 and WEE1 inhibitor adavosertib in TP53 mutated cell lines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1010.

Background: Cetuximab is a licensed anti-EGFR antibody treatment for RAS/BRAF wild type (WT) metastatic colorectal cancer (CRC) but is only effective in a proportion of these patients. Established mechanisms of resistance include primary and secondary activating RAS mutations. However, these cannot explain a proportion of resistant cases. We investigated the differences in early adaptive signaling in cetuximab sensitive and resistant cells using phospho(p)-proteomics in order to elucidate p-proteomic signatures of response, understand resistance mechanisms and suggest future therapeutic strategies. Methods: We used a panel of 12 cell lines (6 cetuximab sensitive and 6 resistant cell lines), cells isolated from CRC patients’ ascites (n=4) and patient derived organoids (n=2). All CRC samples used were RAS/BRAF WT. Following 1 and 4h exposure to cetuximab, a multiplex antibody-based platform was used to simultaneously quantify changes in 60 p-proteins. Key results were validated with Western blotting. Proliferation assays and 2-week colony assays were used to test potential cetuximab combinations. Statistical analysis included logistic regression, T tests and Spearman’s correlation Results: Following 1 and 4h exposure in sensitive cell lines there was downregulation of pHER2 and other intracellular effector p-proteins that function within MAPK, PI3K and JAK-STAT pathways. In contrast, in resistant cell lines at 1h there was a significantly lower degree of pHER2 downregulation and upregulation of pHER3 (p The upregulation/lack of downregulation of the PI3K pathway and upregulation of other pRTKs were confirmed in cetuximab resistant patient derived cells and organoid cultures. We then investigated the combination of cetuximab with: PI3K inhibitor (i), AKTi, mTORi and IGF1Ri. The combination of cetuximab with PI3Ki pictilisib was able to sensitize to cetuximab in the resistant cell lines and organoid cultures with an effect that ranged from additive to synergistic. Conclusion: RAS/BRAF WT sensitive and resistant CRC cells have distinct p-proteomic signatures following 1 and 4h cetuximab exposure. In resistant cells, early adaptive signaling involves upregulation of RTKs and the PI3K pathway. The combination of cetuximab and pictilisib showed a modest benefit, however, overlapping toxicity may render this difficult to deliver clinically. Citation Format: Alexandros Georgiou, Adam Stewart, George Vlachogiannis, Lisa Pickard, Nicola Valeri, David Cunningham, Steven R. Whittaker, Udai Banerji. Proteomic approaches to study cetuximab resistance in RAS/BRAF wild type colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2646.

We report herein a series of Nek2 inhibitors based on an aminopyridine scaffold. These compounds have been designed by combining key elements of two previously discovered chemical series. Structure based design led to aminopyridine (R)-21, a potent and selective inhibitor able to modulate Nek2 activity in cells.

Nek2 is a serine/threonine protein kinase that localizes to the centrosome and is implicated in mitotic regulation. Overexpression of Nek2 induces premature centrosome separation and nuclear defects indicative of mitotic errors, whereas depletion of Nek2 interferes with cell growth. As Nek2 expression is upregulated in a range of cancer cell lines and primary human tumors, inhibitors of Nek2 may have therapeutic value in cancer treatment. The authors used a radiometric proximity assay in a high-throughput screen to identify small-molecule inhibitors of Nek2 kinase activity. The assay was based on the measurement of the radiolabeled phosphorylated product of the kinase reaction brought into contact with the surface of wells of solid scintillant-coated microplates. Seventy nonaggregating hits were identified from approximately 73,000 compounds screened and included a number of toxoflavins and a series of viridin/wortmannin-like compounds. The viridin-like compounds were >70-fold selective for Nek2 over Nek6 and Nek7 and inhibited the growth of human tumor cell lines at concentrations consistent with their biochemical potencies. An automated mechanism-based microscopy assay in which centrosomes were visualized using pericentrin antibodies confirmed that 2 of the viridin inhibitors reduced centrosome separation in a human tumor cell line. The data presented show that pharmacological inhibition of Nek2 kinase results in the expected phenotype of disruption to centrosome function associated with growth inhibition and further supports Nek2 as a target for cancer drug discovery.

AKT is frequently deregulated in cancer, making it an attractive anticancer drug target. CCT128930 is a novel ATP-competitive AKT inhibitor discovered using fragment- and structure-based approaches. It is a potent, advanced lead pyrrolopyrimidine compound exhibiting selectivity for AKT over PKA, achieved by targeting a single amino acid difference. CCT128930 exhibited marked antiproliferative activity and inhibited the phosphorylation of a range of AKT substrates in multiple tumor cell lines in vitro, consistent with AKT inhibition. CCT128930 caused a G1 arrest in PTEN-null U87MG human glioblastoma cells, consistent with AKT pathway blockade. Pharmacokinetic studies established that potentially active concentrations of CCT128930 could be achieved in human tumor xenografts. Furthermore, CCT128930 also blocked the phosphorylation of several downstream AKT biomarkers in U87MG tumor xenografts, indicating AKT inhibition in vivo. Antitumor activity was observed with CCT128930 in U87MG and HER2-positive, PIK3CA-mutant BT474 human breast cancer xenografts, consistent with its pharmacokinetic and pharmacodynamic properties. A quantitative immunofluorescence assay to measure the phosphorylation and total protein expression of the AKT substrate PRAS40 in hair follicles is presented. Significant decreases in pThr246 PRAS40 occurred in CCT128930-treated mouse whisker follicles in vivo and human hair follicles treated ex vivo, with minimal changes in total PRAS40. In conclusion, CCT128930 is a novel, selective, and potent AKT inhibitor that blocks AKT activity in vitro and in vivo and induces marked antitumor responses. We have also developed a novel biomarker assay for the inhibition of AKT in human hair follicles, which is currently being used in clinical trials. Mol Cancer Ther; 10(2); 360–71. ©2010 AACR.

Deregulated AKT signalling is implicated in cancer. The preclinical characterization of AKT inhibitors and development of PD biomarkers are vital prior to clinical trials. Invasive techniques for clinical PD analyses pose ethical and logistical issues, hence hair follicles may represent a non-invasive option. The pyrazole AT7867 and pyrrolopyrimidine CCT128930 are novel ATP-competitive AKT inhibitors from different chemical series developed at The Institute of Cancer Research in collaboration with Astex Therapeutics (Cambridge, UK). AT7867 and CCT128930 have IC50 values against AKT2 of 17nM and 6nM respectively. Growth inhibitory IC50 (GI50) values were 2.4μM and 6.3μM in PTEN-null U87MG glioblastoma cells as measured by SRB assay. Cellular studies of both compounds in U87MG cells were carried out by Meso Scale Discovery (MSD) ELISA, western blot (WB) and immunofluorescence. These showed an initial induction of phosphorylated (p) Ser473 AKT as expected with ATP-competitive AKT inhibitors, and inhibition of downstream AKT targets, including pSer9 GSK-3β, pThr246 PRAS40, pSer127 YAP and pSer235/236 S6RP, indicating AKT pathway blockade. Interestingly, CCT128930 inhibited phosphorylation of AKT targets GSK-3β, S6RP and PRAS40 at lower concentrations (0.5-1µM), compared to AT7867 (5-10µM) in U87MG cells. Phosphorylation was also inhibited at earlier time points with equipotent doses (3XGI50) of CCT128930 versus AT7867. CCT128930 also caused a predominant G0/G1 phase arrest, while AT7867 resulted in a predominant G2 arrest in U87MG cells at equipotent doses (3XGI50), using BrdU and PI staining and flow cytometry. We report for the first time in vivo efficacy with intraperitoneally (ip) or orally administered AT7867 in PTEN-null MES-SA uterine sarcoma and U87MG mouse xenograft models; and ip administered CCT128930 in HER2-overexpressing BT474 breast cancer and U87MG xenografts, which correlated with in vivo pharmacokinetics (PK) and PD biomarker modulation of pSer9 GSK-3β and pSer235/236 S6RP using WB and MSD. Hair follicles were developed as a robust surrogate PD biomarker, with pThr246 PRAS40 as a PD readout. This assay was validated with healthy volunteer hair follicles, which were treated ex vivo with CCT128930. A significant decrease in pThr246 PRAS40 (p In conclusion, by employing an integrated PK and PD biomarker-driven drug discovery strategy, we have developed 2 novel and potent AKT inhibitors with antitumor activity, and have validated a robust surrogate biomarker assay for AKT inhibition for use in clinical trials. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4481.

Background: KRAS is commonly mutated in solid tumors. Cancer-associated fibroblasts (CAFs) are a key tumor stroma component, which can affect cancer progression and drug response. We hypothesized that defining the differential secreted proteins between CAFs and KRAS mutant-cancer cells could reveal potential mechanisms by which CAFs influence cancer progression and drug resistance. Methods: We studied 12 cell lines: 3 KRAS mutant-colorectal cancer cell lines (H747, LIM2099 and SW620), 3 KRAS mutant-lung cancer cell lines (H1792, H2030 and H23), 3 KRAS mutant-pancreatic cancer cell lines (CAPAN1, DANG, MIAPACA2) and 3 CAF cell line models (colorectal and lung CAF and pancreatic stellate cells). We quantified proteins in cell lines and serum-free media after 24 hour incubation in cells using mass spectrometry in a multiplexed manner (12plex) in triplicates to characterize the proteome and the profile of secreted proteins (secretome), respectively. Prediction software (signalP, secretomeP, TMHMM) and databases (surfaceome and cell surface protein atlas) were used to annotate secreted or transmembrane proteins. Results: Our proteome analysis quantified 9307 proteins. T-test between the cell types (CAF vs cancer) identified 1770 differentially expressed proteins, where 712 proteins were CAF-enriched. This included known CAF markers (e.g α smooth muscle actin) but also proteins not known to be CAF markers such as heat shock protein beta-5/6 (HSPB5/6). The secretome analysis identified 2330 secreted or transmembrane proteins where 202 were differentially expressed between cancer cells and CAFs. 190 proteins were CAF-enriched with the highest ranking being syndecan-2 (SDC2), collagen α-28(I) chain (COL28A1), decorin (DCN) and wnt family member 5B (WNT5B). Interestingly, basal proteome analysis of KRAS mutant-cancer cells showed expression of receptors corresponding to the CAF-enriched ligands, such as receptor tyrosine kinase-like orphan receptor 1/2 (ROR1/2) which respond to WNT5B. This suggests that CAF-enriched ligands may activate certain downstream pathways, including non-canonical WNT signaling, in KRAS mutant-cancer cells. Conclusion: We undertook deep quantitative proteomics where we identified potential novel CAF markers HSPB5/6. We have also found proteins in the CAF secretome, such as WNT5B, which may drive drug resistance in KRAS mutant-cancer cells. Citation Format: Rachel Lau, Lu Yu, Theodoros Roumeliotis, Lisa Pickard, Adam Stewart, Jyoti Choudhary, Udai Banerji. Understanding the role of cancer-associated fibroblasts (CAFs) on pathogenesis of KRAS mutated cancers by defining differences in the basal state proteome and secretome [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3187.