Diego Tosi

Clinical Development Strategies and Outcomes in First-in-Human Trials of Monoclonal Antibodies

PURPOSE We conducted a comprehensive review of the design, implementation, and outcome of first-in-human (FIH) trials of monoclonal antibodies (mAbs) to clearly determine early clinical development strategies for this class of compounds. METHODS We performed a PubMed search using appropriate terms to identify reports of FIH trials of mAbs published in peer-reviewed journals between January 2000 and April 2013. RESULTS A total of 82 publications describing FIH trials were selected for analysis. Only 27 articles (33%) reported the criteria used for selecting the starting dose (SD). Dose escalation was performed using rule-based methods in 66 trials (80%). The median number of planned dose levels was five (range, two to 13). The median of the ratio between the highest planned dose and the SD was 27 (range, two to 3,333). Although in 56 studies (68%) at least one grade 3 or 4 toxicity event was reported, no dose-limiting toxicity was observed in 47 trials (57%). The highest planned dose was reached in all trials, but the maximum-tolerated dose (MTD) was defined in only 13 studies (16%). The median of the ratio between MTD and SD was eight (range, four to 1,000). The recommended phase II dose was indicated in 34 studies (41%), but in 25 (73%) of these trials, this dose was chosen without considering toxicity as the main selection criterion. CONCLUSION This literature review highlights the broad design heterogeneity of FIH trials testing mAbs. Because of the limited observed toxicity, the MTD was infrequently reached, and therefore, the recommended phase II dose for subsequent clinical trials was only tentatively defined.

Strategies for clinical development of monoclonal antibodies beyond first-in-human trials: tested doses and rationale for dose selection

Background:Our previous survey on first-in-human trials (FIHT) of monoclonal antibodies (mAbs) showed that, due to their limited toxicity, the recommended phase II dose (RP2D) was only tentatively defined.Methods:We identified, by MEDLINE search, articles on single-agent trials of mAbs with an FIHT included in our previous survey. For each mAb, we examined tested dose(s) and dose selection rationale in non-FIHTs (NFIHTs). We also assessed the correlation between doses tested in the registration trials (RTs) of all FDA-approved mAbs and the corresponding FIHT results.Results:In the 37 dose-escalation NFIHTs, the RP2D indication was still poorly defined. In phase II–III NFIHTs (n=103 on 37 mAbs), the FIHT RP2D was the only dose tested for five mAbs. For 16 mAbs, only doses different from the FIHT RP2D or the maximum administered dose (MAD) were tested and the dose selection rationale infrequently indicated. In the 60 RTs on 27 FDA-approved mAbs with available FIHT, the FIHT RP2D was tested only for two mAbs, and RT doses were much lower than the FIHT MAD.Conclusions:The rationale beyond dose selection in phase II and III trials of mAbs is often unclear in published articles and not based on FIHT data.

Abstract 1187: Synthetic lethality screening reveals ATR as responsible for oxaliplatin resistance in colorectal cancer cells

Despite the recent advances achieved in the treatment of colon cancer, tumor resistance is a frequent cause of chemotherapy failure. Our work was aimed to determine the molecular mechanisms involved in the resistance to oxaliplatin, an anticancer agent widely used in colorectal cancer treatment. To this end, we establish an oxaliplatin-resistant cellular model from the colon adenocarcinoma cell line HCT-116. Among cellular clones obtained, we used one displaying mild resistance (10 fold called HCT116-R1) to perform short hairpin RNA-based loss of function genetic screen in order to identify genes that can modulate the cellular response to oxaliplatin by revealing genes the silencing of which causes drug sensitivity (synthetic lethal interactions with the drug). Using this screen, we have identified ATR (Ataxia-telangiectasia mutated and rad3 related), a protein that plays a key role in the repair of DNA double-strand breaks induced by various DNA damaging agents, including platinum derivatives. We further validated ATR implication in oxaliplatin resistance by showing that (i) shRNA-mediated repression of ATR in HCT116-R1 oxaliplatin-resistant CRC cells sensitizes such cells to the drug; (ii) co-incubation with the ATR inhibitor VE-822 (or VX-970) and oxaliplatin led to a dramatic synergistic effect in six different CRC cell lines (two oxaliplatin-sensitives: HCT116 and SW48; and four oxaliplatin-resistant: HCT116-R1, HCT116-R2, SW48-R1 and SW48-R2) using 2D and 3D cell growth inhibition assays and in vivo. The synergistic effect was evaluated using dose matrix data (an algorithm that was implemented in our group); (iii) the synergistic effect of oxaliplatin and VE-822 was accompanied by an increase of ssDNA, DNA double-strand breaks, growth arrest and apoptosis induction. In conclusion, our preliminary data confirm the results of our screen by demonstrating for the first time the functional role of ATR in the sensitivity to oxaliplatin. Citation Format: Eve Combes, Augusto Faria-Andrade, Diego Tosi, Pierre Martineau, Maguy Del Rio, Roderick Beijersbergen, Nadia Vie, Celine Gongora. Synthetic lethality screening reveals ATR as responsible for oxaliplatin resistance in colorectal cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1187. doi:10.1158/1538-7445.AM2017-1187

Abstract B16: Cetuximab activates Foxo3a via the MAPK p38 to induce apoptosis and reduce cell proliferation in colorectal cancer cells

Cetuximab is a monoclonal antibody against EGFR and is associated with 5-FU and irinotecan for the treatment of patients with colorectal cancer harboring wild type KRAS. However, cetuximab is ineffective in patients with constitutively active mutated KRAS and also in half of the patients with wild type KRAS. As cetuximab downstream cellular targets are not fully characterized, the aim of this study was to identify the signaling pathways activated by cetuximab in CRC cells. Our results show that in addition to inhibiting ERK and AKT, cetuximab also activates the mitogen-activated protein kinase (MAPK) p38. We have showed that p38 inhibition reduced cetuximab efficacy on cell growth and cell death. At the molecular level, cetuximab activates the transcription factor FOXO3a and promotes its nuclear translocation via p38-mediated phosphorylation. FOXO3a phosphorylation and activation by p38 led to the up-regulation of its target genes p27 and BIM and the subsequent induction of apoptosis and inhibition of cell proliferation. Finally, FOXO3a silencing reduced cetuximab cytotoxicity, further confirming FOXO3a role in cetuximab effect. Collectively, our results identify FOXO3a as a key mediator of cetuximab mechanism of action in CRC cells KRAS WT and define p38 as its main activator in this context. Citation Format: Laetitia Marzi, Eve Combes, Nadia VIE, Diego Tosi, Adeline Ayrolles-Torro, Christel Larbouret, Vincent Denis, Laetitia K. Linares, Clara Montagut, Mar Iglesias, Pierre Martineau, Eric W-F Lam, Maguy Del Rio, Celine Gongora. Cetuximab activates Foxo3a via the MAPK p38 to induce apoptosis and reduce cell proliferation in colorectal cancer cells. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr B16.

Abstract 3681: Synergism analysis of dose matrices for combinations of BKM120 (a PI3K inhibitor), MEK162 (a MEK1/2 inhibitor) and chemotherapy in colorectal cancer (CRC) cell lines

Most of targeted cancer drugs are developed in the clinical setting as single agent or as add-on of a standard treatment. Indeed, scarce data are available about the interaction effect in terms of synergism or antagonism for combinations of targeted agents or of targeted and cytotoxic agents at different doses. We studied the interaction effects of combinations of BKM120, MEK162 and SN38 (the active metabolite of irinotecan) on CRC cell lines. A combination drug screening was performed on 7 CRC cell lines, 2 of which previously made resistant to irinotecan. For each cell line the combinations of BKM120 and MEK162, of BKM120 and SN38, and of MEK162 and SN38 were tested. Cell survival was assessed by sulforhodamine B cytotoxic assay in matrices of full-range dose combinations for both drugs. We developed an R script to perform a synergy analysis according to a modified version of the method proposed by Lehar and al. (Nat Biotechnol 2009;27:659-666). This method of analysis allows quantification of synergism or antagonism for each dose combination point in dose matrices of two or more drugs, and yields a synthetic interaction parameter, the combination index (CI). A CI of > 0 indicating synergy, a CI of We could detect a pronounced synergism between BKM120 and MEK162, with a mean combination index of 1.82 for the 7 cell lines tested. Drug combinations including chemotherapy showed less positive interactions. A moderate synergistic interaction was detected between SN38 and MEK162, with a mean CI of 1.16. Combinations of SN38 and BKM120 were mainly additive, with a mean CI of 0.17. Interestingly, the distribution of synergistic effect was not homogeneous over the dose matrices. Analysis of matrices for the BKM120/MEK162 combination showed focal areas with high synergy, which were quite always located in dose regions corresponding to IC10-IC30 for BKM120 and IC20-IC35 for MEK162. On the contrary, analysis of matrices for the BKM/SN38 combination showed focal areas of intense antagonism located in dose regions corresponding to IC15-IC30 for BKM120 and IC5-IC30 for SN38. No clear correlation was detected between, on the one side, the type of pharmacological interaction for all drug combinations tested and, on the other side, the mutational status of KRAS and p53, or sensitivity to irinotecan. Our data show the importance of an extensive preclinical testing of the interaction effects of drug combinations at different doses. We are now performing synergism analysis of three dimension matrices for three-drug combinations. Phosphoproteomic analysis of drug combination effect on this high synergism areas compared to other dose matrix areas is ongoing, with the aim of elucidating the underlying molecular mechanism(s). Citation Format: Diego Tosi, Salima Atis, Caroline Mollevi, Pierre Martineau, Celine Gongora. Synergism analysis of dose matrices for combinations of BKM120 (a PI3K inhibitor), MEK162 (a MEK1/2 inhibitor) and chemotherapy in colorectal cancer (CRC) cell lines. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3681. doi:10.1158/1538-7445.AM2014-3681