Colorectal cancer (CRC) is a genetic disease governed by clonal evolution1. Genotyping CRC tissue is employed for therapeutic purposes but this approach has significant limitations. A tissue sample represents a single snapshot in time, is subjected to selection bias due to tumor heterogeneity, and can be difficult to obtain. We exploited circulating DNA (ctDNA) to genotype colorectal tumors and track clonal evolution during therapies with the anti-EGFR antibodies cetuximab or panitumumab. We identified genomic alterations in KRAS, NRAS, MET, ERBB2, FLT3, EGFR and MAP2K1 in ctDNA of patients with primary or acquired resistance to EGFR blockade. Mutant RAS clones, which rise in blood during EGFR blockade, decline upon withdrawal of anti-EGFR antibodies indicating that clonal evolution continues beyond clinical progression. Pharmacogenomic analysis of CRC cells, which had acquired resistance to cetuximab, reveals that upon antibody withdrawal KRAS clones decay, while the population regains drug sensitivity. ctDNA profiles of patients who benefit from multiple challenging with anti-EGFR antibodies exhibit pulsatile levels of mutant KRAS. These results reveal that the CRC genome adapts dynamically to intermittent drug schedules and provide a molecular explanation for the efficacy of re-challenge therapies based on EGFR blockade.

No abstract

378 Background: BTC is a rare, heterogenous cancer with poor prognosis. Reports on immunogenic features of BTC suggest checkpoint inhibition may result in antitumor immune responses, and limited clinical activity has been seen with single agents in advanced settings. Durvalumab (PD-L1 inhibitor) + GemCis showed promising antitumor activity in advanced BTC in a phase 2 study. TOPAZ-1 (NCT03875235) is the first global phase 3 study to evaluate first-line immunotherapy + GemCis in advanced BTC. Methods: In this double-blind study, pts previously untreated for unresectable locally advanced, recurrent, or metastatic BTC were randomized 1:1 to receive durvalumab (1500 mg every 3 weeks [Q3W]) or placebo + GemCis (Gem 1000 mg/m2 and Cis 25 mg/m2 on Days 1 and 8 Q3W) for up to 8 cycles, followed by durvalumab (1500 mg Q4W) or placebo until disease progression or unacceptable toxicity. Randomization was stratified by disease status (initially unresectable, recurrent) and primary tumor location (intrahepatic cholangiocarcinoma, extrahepatic cholangiocarcinoma, gallbladder cancer). The primary objective was to assess overall survival (OS). Secondary endpoints included progression-free survival (PFS), objective response rate (ORR), and safety. Results: At data cutoff for this interim analysis (11 August 2021), 685 pts were randomized to durvalumab + GemCis (n=341) or placebo + GemCis (n=344; Table). The primary objective was met: durvalumab + GemCis significantly improved OS vs placebo + GemCis (hazard ratio [HR], 0.80; 95% confidence interval [CI], 0.66–0.97; p=0.021). PFS was also significantly improved with durvalumab vs placebo (HR, 0.75; 95% CI, 0.64–0.89; p=0.001). ORR was 26.7% with durvalumab and 18.7% with placebo. Grade 3/4 treatment-related adverse events (TRAEs) occurred in 62.7% of pts receiving durvalumab and 64.9% of pts receiving placebo. TRAEs led to discontinuation of any study medication in 8.9% of pts receiving durvalumab and 11.4% of pts receiving placebo. Conclusions: In pts with advanced BTC, durvalumab + GemCis significantly improved OS and PFS vs placebo + GemCis with manageable safety, indicating durvalumab + GemCis may be a new first-line standard of care regimen. Clinical trial information: NCT03875235. [Table: see text]

No abstract

Despite the introduction of several novel anticancer agents almost 50% of colorectal cancer (CRC) patients die for cancer suggesting the necessity of new therapeutical approaches. In this study we demonstrated that the HDAC inhibitor vorinostat exerted potent antiproliferative effect in a panel of mut-and wt-p53 human CRC cell lines. Moreover, in combination with 5-fluorouracil modulated by folinic acid (5FU-FA) or with Raltitrexed (RTX), both commonly used in the treatment of this disease, it showed a clear schedule-dependent synergistic antiproliferative interaction as demonstrated by calculating combination indexes. Only simultaneous, or 24 h pretreatment with vorinostat followed by either agent, produced synergistic effect paralleled by evident cell cycle perturbations with major S-phase arrest. Moreover, we provided for the first time evidences that vorinostat can overcome resistance to both 5FU and RTX. Downmodulation of Thymidilate synthase (TS) protein induced by vorinostat within 24 h, represented a key factor in enhancing the effects of both drugs in sensitive as well as resistant tumor cells. Furthermore, p53, whose wildtype expression is critical for sensitivity to 5FU and RTX, was upregulated by vorinostat in wt-and downregulated in mut-p53 cells, suggesting an additional mechanism of the antiproliferative synergistic interactions observed. Overall these data add new insights in the mechanism of vorinostat antitumor effect and suggested that the association of vorinostat plus 5FU-FA and/or RTX should be clinically explored.

High expression of the epidermal growth factor receptor (EGFR) has been implicated in the development of squamous-cell carcinomas of head and neck (SCCHN). ZD1839 ('Iressa') is an orally active, selective EGFR-TKI (EGFR-tyrosine kinase inhibitor) that blocks signal transduction pathways implicated in proliferation and survival of cancer cells, and other host-dependent processes promoting cancer growth. We have demonstrated that ZD1839 induces growth arrest in SCCHN cell lines by inhibiting EGFR-mediated signaling. Cell cycle kinetic analysis demonstrated that ZD1839 induces a delay in cell cycle progression and a G1 arrest together with a partial G2/M block; this was associated with increased expression of both p27(KIP1) and p21(CIP1/WAF1) cyclin-dependent kinase (CDK) inhibitors. The activity of CDK2, the main target of CIP/KIP CDK inhibitors, was reduced in a dose-dependent fashion after 24 h of ZD1839 treatment and this effect correlated to the increased amount of p27(KIP1) and p21(CIP1/WAF1) proteins associated with CDK2-cyclin-E and CDK2-cyclin-A complexes. In addition, ZD1839-induced growth inhibition was significantly reduced in cell transfectants expressing p27(KIP1) or p21(CIP1/WAF1) antisense constructs. Overall, these results as well as the timing of the effect of ZD1839 on G1 arrest and p27(KIP1) and p21(CIP1/WAF1) upregulation, suggest a mechanistic connection between these events.

Metformin, an inexpensive, well-tolerated oral agent that is commonly used in the first-line treatment for type 2 diabetes, has become the focus of intense research as a potential anticancer agent. This research reflects a convergence of epidemiologic, clinical, and preclinical evidence, suggesting that metformin may lower cancer risk in diabetics and improve outcomes of many common cancers. Notably, metformin mediates an approximately 30 % reduction in the lifetime risk of cancer in diabetic patients. There is growing recognition that metformin may act (1) directly on cancer cells, primarily by impacting mitochondrial respiration leading to the activation of the AMP-activated protein kinase (AMPK), which controls energy homeostasis in cells, but also through other mechanisms or (2) indirectly on the host metabolism, largely through AMPK-mediated reduction in hepatic gluconeogenesis, leading to reduced circulating insulin levels and decreased insulin/IGF-1 receptor-mediated activation of the PI3K pathway. Support for this comes from the observation that metformin inhibits cancer cell growth in vitro and delays the onset of tobacco carcinogen-induced lung cancer in mice and that metformin and its analog phenformin delay spontaneous tumor development cancer-prone transgenic mice. The potential for both direct antitumor effects and indirect host-mediated effects has sparked enormous interest, but has led to added challenges in translating preclinical findings to the clinical setting. Nonetheless, the accumulation of evidence has been sufficient to justify initiation of clinical trials of metformin as an anticancer agent in the clinical setting, including a large-scale adjuvant study in breast cancer, with additional studies planned.

PurposeTo assess the feasibility and effectiveness of quantitative intravoxel incoherent motion (IVIM) of Diffusion-weighted imaging (DWI) in the assessment of liver metastases treated with targeted chemotherapy agents.Methods12 patients with unresectable liver metastases from colorectal cancer were enrolled and received neoadjuvant FOLFIRI (5-fluorouracil, leucovorin, irinotecan) plus bevacizumab therapy. DWI was performed for 36 metastases at baseline and after 14 days from starting the treatment. In addition to the basic IVIM metrics, the product between pseudo-diffusivity and perfusion fraction was considered as a descriptor roughly analogous to the flow. Median diffusion parameters of Region of Interest (ROI) were used as representative values for each lesion. Normalized parameters in comparison with the median value of spleen were also collected. The percentual change of the diffusion parameters was calculated. The response to chemotherapy was evaluated according the Response Evaluation Criteria in Solid Tumors (RECIST) as calculated on whole-body CT scan obtained three months after treatment. Mann Whitney test and Receiver operating characteristic (ROC) analysis were performed.Results24 lesions were categorized as responding and 12 as not responding. There was no statistically significant difference among absolute and normalized diffusion parameters between the pretreatment and the post-treatment findings. Instead, the perfusion fraction (fp) values showed a statistical difference between responder and non-responder lesions: sensitivity and specificity of fp variation was 62% and 93%, respectively.ConclusionsIVIM parameters represent a valuable tool in the evaluation of the anti-angiogenic therapy in patients with liver metastases from colorectal cancer. A percentage change of fp represents the most effective DWI marker in the assessment of tumor response.