Giuseppe Locatelli

Dual Targeting of CDK and Tropomyosin Receptor Kinase Families by the Oral Inhibitor PHA-848125, an Agent with Broad-Spectrum Antitumor Efficacy

Altered expression and activity of cyclin-dependent kinase (CDK) and tropomyosin receptor kinase (TRK) families are observed in a wide variety of tumors. In those malignancies with aberrant CDK activation, the retinoblastoma protein (pRb) pathway is deregulated, leading to uncontrolled cell proliferation. Constitutive activation of TRKs is instead linked to cancer cell survival and dissemination. Here, we show that the novel small-molecule PHA-848125, a potent dual inhibitor of CDKs and TRKs, possesses significant antitumor activity. The compound inhibits cell proliferation of a wide panel of tumoral cell lines with submicromolar IC50. PHA-848125–treated cells show cell cycle arrest in G1 and reduced DNA synthesis, accompanied by inhibition of pRb phosphorylation and modulation of other CDK-dependent markers. The compound additionally inhibits phosphorylation of TRKA and its substrates in cells, which functionally express this receptor. Following oral administration, PHA-848125 has significant antitumor activity in various human xenografts and carcinogen-induced tumors as well as in disseminated primary leukemia models, with plasma concentrations in rodents in the same range as those found active in inhibiting cancer cell proliferation. Mechanism of action was also confirmed in vivo as assessed in tumor biopsies from treated mice. These results show that the dual CDK-TRK inhibitor PHA-848125 has the potential for being a novel and efficacious targeted drug for cancer treatment. Mol Cancer Ther; 9(8); 2243–54. ©2010 AACR.

Transcriptional Analysis of an E2F Gene Signature as a Biomarker of Activity of the Cyclin-Dependent Kinase Inhibitor PHA-793887 in Tumor and Skin Biopsies from a Phase I Clinical Study

A transcriptional signature of the pan–cyclin-dependent kinase (Cdk) inhibitor PHA-793887 was evaluated as a potential pharmacodynamic and/or response biomarker in tumor and skin biopsies from patients treated in a phase I clinical study. We first analyzed the expression of a number of known E2F-dependent genes that were predicted to be modulated after Cdk2 and Cdk4 inhibition in xenograft tumor and skin samples of mice treated with the compound. This panel of 58 selected genes was then analyzed in biopsies from seven patients treated with PHA-793887 in a phase I dose escalation clinical trial in solid tumors. Quantitative real-time PCR or microarray analyses were done in paired skin and tumor biopsies obtained at baseline and at cycle 1. Analysis by quantitative real-time PCR of the signature in skin biopsies of patients treated at three different doses showed significant transcriptional downregulation with a dose-response correlation. These data show that PHA-793887 modulates genes involved in cell cycle regulation and proliferation in a clinical setting. The observed changes are consistent with its mechanism of action and correlate with target modulation in skin and with clinical benefit in tumors. Mol Cancer Ther; 9(5); 1265–73. ©2010 AACR.

Abstract LB-147: Combination of the MEK inhibitor, pimasertib (MSC1936369B), and the PI3K/mTOR inhibitor, SAR245409, in patients with advanced solid tumors: Results of a phase Ib dose-escalation trial.

Background: The PI3K/mTOR and MAPK signaling pathways are frequently aberrated in tumors and interact to promote growth. This trial investigated simultaneous inhibition of these pathways using a combination of the selective uncompetitive MEK1/2 inhibitor pimasertib and the dual PI3K/mTOR inhibitor SAR245409 (ClinicalTrials.gov NCT01390818). Materials and Methods: This phase Ib, dose-escalation trial (modified 3+3 design) included patients (pts) with solid tumors with frequent activation of these pathways, no approved therapy, and ECOG performance status ≤1. Expansion in selected indications, based on activity signals, was allowed after determination of the maximum tolerated dose (MTD). Pts received 21-day cycles of pimasertib (once-daily, qd) and SAR245409 (qd) at the following dose levels (DLs): DL1, 15/30; DL2a, 30/30; DL2b, 15/50; DL3, 30/50; DL4a, 60/50; DL4b, 30/70; DL5, 60/70; DL6a, 90/70 and DL6b 60/90. The MTD of the combination was the highest dose at which ≤1/6 pts had a dose-limiting toxicity (DLT). Safety, pharmacokinetics (PK), pharmacodynamics (PD) and tumor response were investigated. Results: Of 46 pts treated, 57% were male, the median age was 58.5 years (range 31-82) and 54% had an ECOG PS of 1. The most common primary tumor types were: colorectal (CRC, n=16), pancreatic and non-small cell lung cancer (NSCLC, n=7, each). Dose escalation was stopped at DL6b as 2/3 pts had DLTs; both had grade 3 nausea and/or vomiting, which resolved after supportive care and treatment interruption. The most frequent adverse events (AEs) (all grades) were: diarrhea (54%), fatigue (50%), nausea (41%) and vomiting and dermatitis acneiform (39% each). The median number of initiated cycles was 2 (range 1-16). There were 2 partial responses (KRAS mutated [mt] CRC with neuro-endocrine features and KRAS mt/PIK3CA mt low grade ovarian cancer and another pt with low grade ovarian cancer had 29% tumor shrinkage) and 7 other pts had stable disease lasting >12 weeks (CRC [n=2, 1 KRAS wild-type (wt) and 1 KRAS mt]; KRAS mt NSCLC [n=2]; and BRAF wt melanoma, KIT mt soft palate cancer and PIK3CA mt bladder cancer [n=1, each]). The MTD was DL6a (pimasertib 90 mg / SAR 245409 70 mg). DL5 (60/70) was the recommended phase II dose (RP2D) based on pimasertib tolerability after prolonged exposure in monotherapy program. Four disease-specific expansion cohorts (CRC, triple-negative breast cancer, NSCLC and melanoma, 18 pts each) are being treated at this dose. Dose escalation with twice-daily administration is ongoing. Preliminary PK and PD data showed no apparent drug-drug interaction. Conclusions: The combination of pimasertib and SAR245409 qd is feasible. The MTD and RP2D for the combination are within the range of the active doses of each drug as monotherapy. Early signals of activity have been observed. Citation Format: Jeffrey R. Infante, Leena Gandi, Geoffrey Shapiro, Naiyer Rizvi, Howard A. Burris, Johanna C. Bendell, Jose Baselga, Karl Hsu, Oliver von Richter, Giuseppe Locatelli, Ekaterine Asatiani, Rebecca S. Heist. Combination of the MEK inhibitor, pimasertib (MSC1936369B), and the PI3K/mTOR inhibitor, SAR245409, in patients with advanced solid tumors: Results of a phase Ib dose-escalation trial. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-147. doi:10.1158/1538-7445.AM2013-LB-147

Transcriptional analysis of the Aurora inhibitor Danusertib leading to biomarker identification in TP53 wild type cells.

Aurora kinases represent an appealing target for anticancer therapies and several Aurora inhibitors are in clinical development, including the potent pan-Aurora inhibitor Danusertib. Treatment with Aurora inhibitors has been shown to induce diverse biological responses in different tumor cells, in part depending on TP53 status. To characterize the effects of Danusertib at the transcriptional level we carried out gene expression profiling of wt and TP53 mutant tumor cells showing differential cell cycle response upon drug treatment. We found that treatment with Danusertib induces a strong transcriptional response only in TP53 wt cells, with an overlapping pattern of expression of TP53-dependent genes among the three cell lines tested, while a prevalent signature could not be identified in the two TP53 mutant cells, suggesting that TP53 status is a key determinant for the observed transcriptional effects. This work led to the identification of a number of genes consistently modulated by Aurora treatment in TP53 cells. One of these is GDF15, a secreted protein belonging to the TGF-β superfamily, for which we found a potential role in resistance to Danusertib, and which could represent a potential biomarker for Danusertib treatment in TP53 WT tumors and in surrogate tissues such as blood or skin.

Recent Developments of c‐Met as a Therapeutic Target in Hepatocellular Carcinoma

Aberrant c‐Met activity has been implicated in the development of hepatocellular carcinoma (HCC), suggesting that c‐Met inhibition may have therapeutic potential. However, clinical trials of nonselective kinase inhibitors with c‐Met activity (tivantinib, cabozantinib, foretinib, and golvatinib) in patients with HCC have failed so far to demonstrate significant efficacy. This lack of observed efficacy is likely due to several factors, including trial design, lack of patient selection according to tumor c‐Met status, and the prevalent off‐target activity of these agents, which may indicate that c‐Met inhibition is incomplete. In contrast, selective c‐Met inhibitors (tepotinib, capmatinib) can be dosed at a level predicted to achieve complete inhibition of tumor c‐Met activity. Moreover, results from early trials can be used to optimize the design of clinical trials of these agents. Preliminary results suggest that selective c‐Met inhibitors have antitumor activity in HCC, with acceptable safety and tolerability in patients with Child‐Pugh A liver function. Ongoing trials have been designed to assess the efficacy and safety of selective c‐Met inhibition compared with standard therapy in patients with HCC that were selected based on tumor c‐Met status. Thus, c‐Met inhibition continues to be an active area of research in HCC, with well‐designed trials in progress to investigate the benefit of selective c‐Met inhibitors. (Hepatology 2018;67:1132–1149)

Does c-Met remain a rational target for therapy in patients with EGFR TKI-resistant non-small cell lung cancer?

Non-small cell lung cancer (NSCLC) inevitably develops resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) treatment. In 5-20% of cases, this can be attributed to aberrant c-Met activity, providing a clear rationale for the use of c-Met inhibitors in these patients. EGFR TKI-resistant tumors often remain sensitive to EGFR signaling, such that c-Met inhibitors are likely to be most effective when combined with continued EGFR TKI therapy. The phase III trials of the c-Met inhibitors onartuzumab and tivantinib, which failed to demonstrate significant benefit in patients with NSCLC but excluded patients with EGFR TKI-resistant disease, do not allow c-Met to be dismissed as a rational target in EGFR TKI-resistant NSCLC. Selective c-Met TKIs exhibit more favorable properties, targeting both hepatocyte growth factor (HGF)-dependent and -independent c-Met activity, with a reduced risk of toxicity compared to non-selective c-Met TKIs. Phase Ib/II trials of the selective c-Met TKIs capmatinib and tepotinib have shown encouraging signs of efficacy. Factors affecting the success of ongoing and future trials of c-Met inhibitors in patients with EGFR TKI-resistant, c-Met-positive NSCLC are considered.