Antonio Avallone

Clonal evolution and resistance to EGFR blockade in the blood of colorectal cancer patients

Colorectal cancers (CRCs) evolve by a reiterative process of genetic diversification and clonal evolution. The molecular profile of CRC is routinely assessed in surgical or bioptic samples. Genotyping of CRC tissue has inherent limitations; a tissue sample represents a single snapshot in time, and it is subjected to spatial selection bias owing to tumor heterogeneity. Repeated tissue samples are difficult to obtain and cannot be used for dynamic monitoring of disease progression and response to therapy. We exploited circulating tumor DNA (ctDNA) to genotype colorectal tumors and track clonal evolution during treatment with the epidermal growth factor receptor (EGFR)-specific antibodies cetuximab or panitumumab. We identified alterations in ctDNA of patients with primary or acquired resistance to EGFR blockade in the following genes: KRAS, NRAS, MET, ERBB2, FLT3, EGFR and MAP2K1. Mutated KRAS clones, which emerge in blood during EGFR blockade, decline upon withdrawal of EGFR-specific antibodies, indicating that clonal evolution continues beyond clinical progression. Pharmacogenomic analysis of CRC cells that had acquired resistance to cetuximab reveals that upon antibody withdrawal KRAS clones decay, whereas the population regains drug sensitivity. ctDNA profiles of individuals who benefit from multiple challenges with anti-EGFR antibodies exhibit pulsatile levels of mutant KRAS. These results indicate that the CRC genome adapts dynamically to intermittent drug schedules and provide a molecular explanation for the efficacy of rechallenge therapies based on EGFR blockade.

Critical role of both p27KIP1 and p21CIP1/WAF1 in the antiproliferative effect of ZD1839 ('Iressa'), an epidermal growth factor receptor tyrosine kinase inhibitor, in head and neck squamous carcinoma cells.

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 p27KIP1 and p21CIP1/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 p27KIP1 and p21CIP1/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 p27KIP1 or p21CIP1/WAF1 antisense constructs. Overall, these results as well as the timing of the effect of ZD1839 on G1 arrest and p27KIP1 and p21CIP1/WAF1 upregulation, suggest a mechanistic connection between these events.

New Perspective for an Old Antidiabetic Drug: Metformin as Anticancer Agent

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.

Synergistic Antitumor Activity of Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor Gefitinib and IFN-α in Head and Neck Cancer Cells In vitro and In vivo

Purpose: Epidermal growth factor receptor (EGFR) overexpression has been implicated in the development of head and neck squamous cell carcinomas (HNSCC) and represents a potential therapeutic target for this disease. We have reported previously that growth inhibitory concentrations of IFN-α enhance the expression and activity of EGFR and that this effect could represent an escape mechanism to the growth inhibition and apoptotic cell death induced by IFN-α. In this study, we investigate whether the combination of IFN-α and gefitinib (Iressa, AstraZeneca Pharmaceuticals, Macclesfield, United Kingdom), a selective EGFR tyrosine kinase inhibitor, might have a cooperative antitumor effect on HNSCC-derived cell lines. Experimental Design: The interaction of IFN-α and gefitinib was evaluated in vitro on HNSCC-derived cell lines by median drug effect analysis calculating a combination index with CalcuSyn software and in vivo by using HNSCC xenografts in nude mice. The mechanism of gefitinib and IFN-α interactions was also studied by analysis of cell cycle kinetics, apoptosis assays, and Western blotting of EGFR signal transduction components. Results: Simultaneous exposure to gefitinib and IFN-α produced synergistic antiproliferative and proapoptotic effects compared with single drug treatment. Furthermore, daily treatment of gefitinib (50 mg/kg p.o.) in combination with an IFN-α regimen (50,000 units s.c. three times weekly) induced tumor growth delay and increased survival rate on established HNSCC xenografts in nude mice. Moreover, the concomitant treatment with gefitinib suppressed the stimulation of extracellular signal-regulated kinase phosphorylation/activity induced by IFN-α both in vitro and in vivo. Conclusion: The observed cooperative antitumor effects could be, at least in part, explained by the inhibition exerted by gefitinib of an IFN-α-induced EGF-dependent survival pathway, which involves extracellular signal-regulated kinase activation. These results provide a rationale for the clinical evaluation of gefitinib in combination with IFN-α in HNSCC.

Modulation of thymidilate synthase and p53 expression by HDAC inhibitor vorinostat resulted in synergistic antitumor effect in combination with 5FU or Raltitrexed

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 hrs 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. Down-modulation of TS protein induced by vorinostat within 24 hrs, represented a key factor in enhancing the effects of both drugs in sensitive as well as resistant tumor cells. Furthermore, p53, whose wild-type expression is critical for sensitivity to 5FU and RTX, was up-regulated by vorinostat in wt- and down-regulated 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.

Phase I study of Caelyx (doxorubicin HCL, pegylated liposomal) in recurrent or metastatic head and neck cancer

BACKGROUND Pegylated liposome technology represents a favourable drug-carrier system, since stealth liposomal drugs have a reduced clearance with prolonged circulation half-life and selective drug accumulation in tissues with increased vascular permeability, such as tumor tissues. Caelyx is a pegylated liposome containing doxorubicin, which has been developed to target drug delivery to cancer cells, thus reducing toxicities. Biodistribution studies have shown a selective tumor uptake in patients with advanced head and neck cancer (HNC), thus justifying the present phase I study. PATIENTS AND METHODS Patients with recurrent or metastatic HNC were treated with Caelyx administered at the starting dose of 30 mg/m2 every three weeks and escalated by 5 mg/m2 per step. Dose escalation was stopped if more than a third of patients of a given cohort had dose-limiting toxicity (DLT), which was defined as grade 4 neutropenia or thrombocytopenia, grade 3 febrile neutropenia, grade 3 thrombocytopenia with bleeding, grade 3 non-hematologic toxicity (except for nausea and alopecia), or > 2 week delay in chemotherapy recycling. The above dose level was defined as maximum tolerated dose (MTD) and the dose level immediately below was recommended for phase II evaluation. Response was evaluated after three courses of chemotherapy. RESULTS Twenty-four patients were treated at five dose levels. At 50 mg/m2, three out of six patients had grade 3 stomatitis; therefore, this level was defined as MTD and 45 mg/m2 was the selected dose for phase II. Stomatitis occurred in 11 patients across all dose levels, considering all delivered cycles. Neutropenia occurred in 10 of 24 patients, but reached grade 4 in only 2 patients at fourth dose level. Skin toxicity, mainly appearing in the form of palmar-plantar erythrodysestesia, was the most frequent toxicity, occurring in 14 patients. Other side effects were mild. One complete response (4%) and seven partial responses (29%) were observed, for an overall response rate of 33% (95% confidence interval (95% CI): 16%-55%). CONCLUSIONS Caelyx is a safe and promising new treatment in HNC, that deserves further evaluation both alone and integrated within chemo-radiotherapy strategies.

Biweekly oxaliplatin, raltitrexed, 5-fluorouracil and folinic acid combination chemotherapy during preoperative radiation therapy for locally advanced rectal cancer: a phase I–II study

Oxaliplatin (OXA), raltitrexed (RTX), 5-fluorouracil (FU) and folinic acid (FA) have shown activity in metastatic colorectal cancer, radioenhancing effect and synergism when combined. We evaluated a chemotherapy (CT) combination of OXA, RTX and FU/FA during preoperative radiotherapy (RT) in locally advanced rectal cancer (LARC) patients. Fifty-one patients with LARC at high risk of recurrence (T4, N+ or T3N0 ⩽5 cm from anal verge and/or circumferential resection margin ⩽5 mm) received three biweekly courses of CT during pelvic RT (45 Gy). Surgery was planned 8 weeks after CT-RT. Recommended doses (RDs) determined during phase I were utilised in the subsequent phase II trial, where the rate of tumour regression grade (TRG) 1 or 2 was the main end point. No toxic deaths occurred, and severe toxicity was easily managed. In phase II, RDs delivered in 31 patients were OXA 100 mg m−2 and RTX 2.5 mg m−2 on day 1, and FU 900 mg m−2 and LFA 250 mg m−2 on day 2. Main severe toxicities by patients were grade 4 neutropenia (23%) and grade 3 diarrhoea (19%). In 71% (95% confidence limits, 52–86%) of patients, TRG1 (13) or TRG2 (9) was obtained. All patients are alive and recurrence-free after a median follow-up of 29 months. Combination of OXA, RTX and FU/FA with pelvic RT has an acceptable toxicity and a high clinical activity in LARC and should be studied further in patients at high risk of recurrence.

Vorinostat synergises with capecitabine through upregulation of thymidine phosphorylase.

Background:Potentiation of anticancer activity of capecitabine is required to improve its therapeutic index. In colorectal cancer (CRC) cells, we evaluated whether the histone deacetylase-inhibitor vorinostat may induce synergistic antitumour effects in combination with capecitabine by modulating the expression of thymidine phosphorylase (TP), a key enzyme in the conversion of capecitabine to 5-florouracil (5-FU), and thymidylate synthase (TS), the target of 5-FU.Methods:Expression of TP and TS was measured by real-time PCR, western blotting and immunohistochemistry. Knockdown of TP was performed by specific small interfering RNA. Antitumour activity of vorinostat was assessed in vitro in combination with the capecitabine active metabolite deoxy-5-fluorouridine (5′-DFUR) according to the Chou and Talay method and by evaluating apoptosis as well as in xenografts-bearing nude mice in combination with capecitabine.Results:Vorinostat induced both in vitro and in vivo upregulation of TP as well as downregulation of TS in cancer cells, but not in ex vivo treated peripheral blood lymphocytes. Combined treatment with vorinostat and 5′-DFUR resulted in a synergistic antiproliferative effect and increased apoptotic cell death in vitro. This latter effect was impaired in cells where TP was knocked. In vivo, vorinostat plus capecitabine potently inhibited tumour growth, increased apoptosis and prolonged survival compared with control or single-agent treatments.Conclusions:Overall, this study suggests that the combination of vorinostat and capecitabine is an innovative antitumour strategy and warrants further clinical evaluation for the treatment of CRC.

Biweekly irinotecan or raltitrexed plus 6S-leucovorin and bolus 5-fluorouracil in advanced colorectal carcinoma: A Southern Italy Cooperative Oncology Group phase II–III randomized trial

PURPOSE The aim of this randomised trial was to evaluate the activity and toxicity of a biweekly regimen including 6S-leucovorin-modulated 5-fluorouracil (LFA-5-FU), combined with either irinotecan (CPT-11 + LFA 5-FU) or raltitrexed (Tomudex) (TOM + LFA-5-FU), in advanced colorectal cancer patients, and to make a preliminary comparison of both these experimental regimens with a biweekly administration of LFA-5-FU modulated by methotrexate (MTX + LFA-5-FU). PATIENTS AND METHODS One hundred fifty-nine patients with advanced colorectal carcinoma previously untreated for the metastatic disease (34 of them previously exposed to adjuvant 5-FU) were randomly allocated to receive: CPT-11, 200 mg/m2 i.v. on day 1, followed on day 2 by LFA, 250 mg/m2 i.v. infusion and 5-FU, 850 mg/m2 s i.v. bolus (arm A); TOM, 3 mg/m2 i.v. on day 1, followed on day 2 by LFA, 250 mg/m2 i.v. infusion and 5-FU, 1050 mg/m2 i.v. bolus (arm B); or MTX, 750 mg/m2 i.v. on day 1, followed on day 2 by LFA, 250 mg/m2 i.v. infusion and 5-FU, 800 mg/m2 i.v. bolus (arm C). Courses were repeated every two weeks in all arms of the trial. Response rate (RR) was evaluated after every four courses. The sample size was defined to have an 80% power to detect a 35% RR for each experimental treatment, and to show a difference of at least 4% in RR with the standard treatment if the true difference is 15% or more. RESULTS The RRs were: 34% (95% confidence interval (95%, CI): 21%-48%) in arm A, including 3 complete responses (CRs) and 15 partial responses (PRs), 24% (95% CI: 14%-38%) in arm B, including 2 CRs and 11 PRs, and 24% (95% CI: 14%-38%), with 2 CRs and 11 PRs, in arm C. After a median follow-up time of 62 (range 18-108) weeks, the median time to progression was 38, 25, and 27 weeks for arm A, B, and C, respectively. With 94 patients still alive, the one-year probability of survival was 61%, 54%, and 59%, respectively. WHO grade 3 or 4 neutropenia and diarrhoea affected 46% and 16%, respectively, of patients treated with CPT-11 + LFA 5-FU. Median relative dose intensity over eight cycles (DI8) was 78% for CPT-11 and 82% for 5-FU. Severe toxicities of TOM + LFA-5-FU were neutropenia (16%) and diarrhoea (16%), but median relative DI8 was 93% for TOM, and 82% for 5-FU. CONCLUSIONS CPT-11 + LFA-5-FU compares favorably in term of activity and toxicity with other combination regimens including CPT-11 and continuous infusional 5-FU. The hypothesis of a RR 15% higher than the MTX + LFA-5-FU treatment can not be ruled out after this interim analysis. The TOM + LFA 5-FU regimen showed a RR and a toxicity profile very close to the MTX + LFA 5-FU combination, and dose not deserve further evaluation in advanced colorectal cancer patients.

Early Assessment of Colorectal Cancer Patients with Liver Metastases Treated with Antiangiogenic Drugs: The Role of Intravoxel Incoherent Motion in Diffusion-Weighted Imaging

Purpose To 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. Methods 12 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. Results 24 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. Conclusions IVIM 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.