Phase I study of the checkpoint kinase 1 inhibitor GDC-0575 in combination with gemcitabine in patients with refractory solid tumors.

BACKGROUND: Checkpoint kinase 1 (Chk1) inhibition following chemotherapy-elicited DNA damage overrides cell cycle arrest and induces mitotic catastrophe and cell death. GDC-0575 is a highly-selective oral small-molecule Chk1 inhibitor that results in tumor shrinkage and growth delay in xenograft models. We evaluated the safety, tolerability, and pharmacokinetic properties of GDC-0575 alone and in combination with gemcitabine. Antitumor activity and Chk1 pathway modulation were assessed. PATIENTS AND METHODS: In this phase I open-label study, in the dose escalation stage, patients were enrolled in a GDC-0575 monotherapy Arm (1) or GDC-0575 combination with gemcitabine Arm (2) to determine the maximum tolerated dose. Patients in arm 2 received either i.v. gemcitabine 1000 mg/m2 (arm 2a) or 500 mg/m2 (arm 2b), followed by GDC-0575 (45 or 80 mg, respectively, as RP2D). Stage II enrolled disease-specific cohorts. RESULTS: Of 102 patients treated, 70% were female, the median age was 59 years (range 27-85), and 47% were Eastern Cooperative Oncology Group PS 0. The most common tumor type was breast (37%). The most frequent adverse events (all grades) related to GDC-0575 and/or gemcitabine were neutropenia (68%), anemia (48%), nausea (43%), fatigue (42%), and thrombocytopenia (35%). Maximum concentrations of GDC-0575 were achieved within 2 hours of dosing, and half-life was ∼23 hours. No pharmacokinetic drug-drug interaction was observed between GDC-0575 and gemcitabine. Among patients treated with GDC-0575 and gemcitabine, there were four confirmed partial responses, three occurring in patients with tumors harboring TP53 mutation. Pharmacodynamic data were consistent with GDC-0575 inhibition of gemcitabine-induced expression of pCDK1/2. CONCLUSION: GDC-0575 can be safely administered as a monotherapy and in combination with gemcitabine; however, overall tolerability with gemcitabine was modest. Hematological toxicities were frequent but manageable. Preliminary antitumor activity was observed but limited to a small number of patients with a variety of refractory solid tumors treated with GDC-0575 and gemcitabine. CLINICAL TRIAL NUMBER: NCT01564251.

A Phase 1 study of ARQ 087, an oral pan-FGFR inhibitor in patients with advanced solid tumours.

BACKGROUND: ARQ 087 is an orally administered pan-FGFR inhibitor with multi-kinase activity. This Phase 1 study evaluated safety, pharmacokinetics, and pharmacodynamics of ARQ 087 and defined the recommended Phase 2 dose (RP2D). METHODS: Patients with advanced solid tumours received ARQ 087 administered initially at 25 mg every other day and dose-escalated from 25 to 425 mg daily (QD) continuous dosing. FGF19, 21, 23, and serum phosphate were assessed as potential biomarkers of target engagement. RESULTS: 80 patients were enrolled, 61 in dose-escalation/food-effect cohorts and 19 with pre-defined tumour types in the expansion cohort. The most common ARQ 087-related adverse events were fatigue (49%), nausea (46%), aspartate aminotransferase (AST) increase (30%), and diarrhoea (23%). Four patients (5%) experienced grade 1 treatment-related hyperphosphataemia. Dose-limiting toxicity was reversible grade 3 AST increase. The RP2D was 300 mg QD. Pharmacokinetics were linear and dose-proportional from 25 to 325 mg QD, and were unaffected by food. Statistically significant changes (P-value<0.05) suggest phosphate and FGF19 levels as markers of target engagement. In 18 evaluable patients with FGFR genetic alterations, 3 confirmed partial responses (two intrahepatic cholangiocarcinomas (iCCA) with FGFR2 fusions and one urothelial cancer with FGFR2 and FGF19 amplification) and two durable stable disease at ⩾16 weeks with tumour reduction (FGFR2 fusion-positive iCCA and adrenocortical carcinoma with FGFR1 amplification) were observed. CONCLUSIONS: ARQ 087 had manageable toxicity at the RP2D of 300 mg QD, showed pharmacodynamics effects, and achieved objective responses, notably in patients with FGFR2 genetic alterations.

BET inhibitors: a novel epigenetic approach.

Epigenetics has been defined as 'the structural adaptation of chromosomal regions so as to register, signal or perpetuate altered activity states.' Currently, several classes of anticancer drugs function at the epigenetic level, including inhibitors of DNA methyltransferase, histone deacetylase (HDAC), lysine-specific demethylase 1, zeste homolog 2, and bromodomain and extra-terminal motif (BET) proteins.BET proteins have multiple functions, including the initiation and elongation of transcription and cell cycle regulation. In recent years, inhibitors of BET proteins have been developed as anticancer agents. These inhibitors exhibit selectivity for tumor cells by preferentially binding to superenhancers, noncoding regions of DNA critical for the transcription of genes that determine a cell's identity. Preclinical research on BET inhibitors has identified them as a potential means of targeting MYC.Early clinical trials with BET inhibitors have had mixed results, with few responses in both hematologic and solid tumors that tend to be short-lived. Toxicities have included severe, thrombocytopenia, fatigue, nausea, vomiting, and diarrhea; GI side-effects, fatigue, and low-grade dysgeusia have limited compliance. However, preclinical data suggest that BET inhibitors may have a promising future in combination with other agents. They appear to be able to overcome resistance to targeted agents and have strong synergy with immune checkpoint inhibitors as well as with multiple epigenetic agents, particularly HDAC inhibitors. In many instances, BET and HDAC inhibitors were synergistic at reduced doses, suggesting a potential means of avoiding the overlapping toxicities of the two drug classes.BET inhibitors provide a novel approach to epigenetic anticancer therapy. However, to date they appear to have limited efficacy as single agents. A focus on BET inhibitors in combination with other drugs such as targeted and/or as other epigenetic agents is warranted, due to limited monotherapy activity, including pharmacodynamic correlatives differential activity amongst select drug combinations.

A phase I, first in human study of FP-1039 (GSK3052230), a novel FGF ligand trap, in patients with advanced solid tumors.

BACKGROUND: Fibroblast growth factors (FGFs) play important roles in multiple cancers by supporting tumor growth and angiogenesis. FP-1039 (GSK3052230) is a FGF ligand trap consisting of the extracellular domain of FGF receptor 1 (FGFR1) fused with the Fc region of IgG1. FP-1039 binds and neutralizes multiple FGFs that normally bind FGFR1. The primary objective of this phase I study was to evaluate the safety and tolerability of FP-1039. PATIENTS AND METHODS: Eligible patients with metastatic or locally advanced solid tumors for which standard treatments were ineffective were treated with weekly doses of FP-1039 for 4 weeks, followed by 2 weeks observation. RESULTS: Thirty-nine subjects received a mean of 6 infusions of FP-1039 at doses ranging from 0.5 to 16 mg/kg weekly, with no maximally tolerated dose identified. Grade 3 or greater treatment emergent adverse events were uncommon. Four dose-limiting toxicities were reported at doses of 0.75 mg/kg (urticaria), 1 mg/kg (intestinal perforation and neutropenia), and 16 mg/kg (muscular weakness). Drug exposure was dose proportional, and the terminal elimination half-life was 2.6-3.9 days following a single dose. Target engagement as measured by low free plasma FGF2 levels was achieved. FGF pathway dysregulation was uncommon. No objective responses were observed. CONCLUSION: In nonselected cancer patients with advanced disease, treatment with FP-1039 was well tolerated and toxicities associated with small molecule drugs that inhibit FGFR tyrosine kinases, including hyperphosphatemia, were not observed. Further studies of FP-1039 in patients selected for FGF pathway dysregulation, who are most likely to benefit, are now underway.

Phase I study of PD 0332991, a cyclin-dependent kinase inhibitor, administered in 3-week cycles (Schedule 2/1).

BACKGROUND: This phase I, open-label, first-in-human study determined dose-limiting toxicities (DLTs) and maximum tolerated dose (MTD) of PD 0332991, an oral cyclin-dependent kinase 4/6 inhibitor with potent anti-proliferative activity in vitro/vivo. METHODS: A total of 33 patients with retinoblastoma protein-positive advanced solid tumours or non-Hodgkin's lymphoma refractory to standard therapy or for which no therapy was available received PD 0332991 once daily (QD) for 14 days followed by 7 days off treatment (21-day cycles; Schedule 2/1). RESULTS: Six patients had DLTs (18%; four receiving 200 mg QD; two receiving 225 mg QD); the MTD was 200 mg QD. Treatment-related, non-haematological adverse events occurred in 29 patients (88%) during cycle 1 and 27 patients (82%) thereafter. Adverse events were generally mild-moderate. Of 31 evaluable patients, one with testicular cancer achieved a partial response; nine had stable disease (≥10 cycles in three cases). PD 0332991 was slowly absorbed (mean T(max) 4.2 h) and eliminated (mean half-life 26.7 h). Volume of distribution was large (mean 3241 l) with dose-proportional exposure. Using a maximum effective concentration model, neutropenia was proportional to exposure. CONCLUSION: PD 0332991 was generally well tolerated, with DLTs related mainly to myelosuppression. The MTD, 200 mg QD, is recommended for phase II study.

In vivo-in vitro correlation of myelotoxicity of 9-methoxypyrazoloacridine (NSC-366140, PD115934) to myeloid and erythroid hematopoietic progenitors from human, murine, and canine marrow.

BACKGROUND: 9-Methoxypyrazoloacridine (PZA) is an anticancer agent that shows selectivity of action for carcinomas over leukemias. It also has nearly equal potency against cycling and quiescent or hypoxic and normoxic target cells. Phase I trials of PZA in humans are nearing completion. PURPOSE: This study was conducted to determine (a) if PZA is directly inhibitory to hematopoietic cells and, if it is, to characterize the inhibition pharmacodynamically, (b) whether species-specific differences in direct toxicity could explain differences in myelosuppression in mice, dogs, and humans, and (c) whether in vitro data correlate with in vivo myelosuppression data. METHODS: In vitro clonogenic assays of hematopoietic progenitors of myeloid and erythroid lineages from human, canine, and murine femoral marrow were used to measure the direct toxicity of PZA. Results from these assays were compared on an area-under-the-curve (AUC) basis to clinical myelosuppression data. RESULTS: On the basis of maximum tolerated concentrations, canine hematopoietic progenitors are most susceptible to PZA, followed by human and then murine progenitors. We found no difference in susceptibility to PZA toxicity between the human progenitors of myeloid and erythroid lineages. Both concentration and duration of exposure contribute to the in vitro toxicity of PZA. In contrast to antimetabolites, the in vitro toxicity of PZA could be minimized at a given AUC by lowering drug concentration and prolonging the period of exposure. On an AUC basis, the in vitro data are consistent with limited in vivo myelosuppression data from preclinical models and correlate with neutropenia data from a phase I trial. CONCLUSIONS: PZA directly inhibits hematopoietic progenitors, an action that is responsible for the myelosuppression observed in humans. Human marrow appears able to compensate for the loss of up to 35% of its myeloid progenitors, in that peripheral neutrophil counts remain unchanged at that level of loss. Although in vivo studies show that prolonged infusion reduces myelosuppression at a given total dose in both rodent and canine models, pharmacokinetic differences make it unlikely that this approach will benefit human patients. IMPLICATIONS: The in vitro data quantitatively predict the AUCs at maximum tolerated dose in preclinical models and human patients. Thus, in vitro clonogenic assays of myelotoxic agents can provide data that make both preclinical toxicology testing and clinical trial planning and interpretation more efficient and accurate.

Antitumor efficacy of interleukin-2 alone and in combination with adriamycin and dacarbazine in murine solid tumor systems.

Recombinant interleukin-2 (IL-2)/chemotherapy combinations have recently entered clinical trial. The rationale for sequencing has primarily been empiric or based on in vitro data. To establish in vivo models for chemoimmunotherapy trials, we investigated IL-2 alone and in combination with dacarbazine (DTIC) and adriamycin. IL-2 (as a single agent given i.v. at 1-3 x 10(5) Cetus units once daily for 5 days, repeated 7-10 days later), was highly active against an immunogenic line of colon adenocarcinoma no. 11/A [tumor growth inhibition (T/C) = 0% with cures]. It was modestly active against colon adenocarcinoma no. 38 (T/C = 39%), mammary adenocarcinoma no. 16/C (T/C = 18%), and B16 melanoma (T/C = 21%). IL-2 was inactive against colon adenocarcinoma no. 7/A (T/C = 83%). Combination trials were done using DTIC and IL-2 against colon no. 7/A and upstaged colon no. 11/A. The combination of adriamycin and IL-2 was tested against mammary adenocarcinoma no. 16/C. In the DTIC/IL-2 combination trials, the combination was superior over either agent used alone. In the IL-2/adriamycin trials, the combination was no better than adriamycin alone at optimum dosages.

Multicenter phase II study of capecitabine in paclitaxel-refractory metastatic breast cancer.

PURPOSE: Capecitabine is a novel, oral, selectively tumor-activated fluoropyrimidine carbamate. This large multicenter phase II trial tested the efficacy and safety of twice-daily oral capecitabine at 2,510 mg/m2/d given for 2 weeks followed by a 1-week rest period and repeated in 3-week cycles, in patients with paclitaxel-refractory metastatic breast cancer. PATIENTS AND METHODS: Patients were to have received at least two but not more than three prior chemotherapeutic regimens, one of which had to have contained paclitaxel given for metastatic disease. One hundred sixty-three patients were entered onto the study at 25 centers, and 162 patients received capecitabine. One hundred thirty-five patients had bidimensionally measurable disease, and 27 patients had assessable disease. RESULTS: The overall response rate was 20% (95% confidence interval, 14% to 28%). All responding patients were resistant to or had failed paclitaxel, and all had received an anthracycline. Three complete responses were seen, with complete response durations of 106, 109, and 194+ days. Median duration of response was 8.1 months, median survival time was 12.8 months, and the median time to disease progression was 93 days. The most common treatment-related adverse events were hand-foot syndrome, diarrhea, nausea, vomiting, and fatigue. Diarrhea (14%) and hand-foot syndrome (10%) were the only treatment-related adverse events that occurred with grade 3 or 4 intensity in more than 10% of patients. CONCLUSION: Capecitabine is an active drug in the treatment of paclitaxel-refractory metastatic breast cancer. It has a favorable toxicity profile with the added advantage of being an oral drug administered at home.

Pharmacokinetic studies in mice of two new thioxanthenones (183577 and 232759) that showed preferential solid tumor activity.

Two new thioxanthenones, 183577 and 232759, have rekindled interest in the development of representatives from this class of structures as useful anticancer agents. Although the mechanism of action is unknown, both compounds demonstrated a similar spectrum of solid tumor selectivity. 232759 was selected for clinical development because it showed no hepatotoxicity in preliminary studies, whereas 183577 showed hepatotoxicity but only at the maximum tolerated dose (MTD). The limiting toxicity for the clinical candidate was myelosuppression in preliminary studies. Plasma and tissue drug levels, as well as protein binding, were studied in mice using optimal administration times at the MTD for each drug (for 183577, this was a 4-h infusion at 1350 mg/m2 and for 232759, it was a 5-min injection at 240 mg/m2), as well as at one-half the MTD for the clinical candidate. The drugs were 96-100% bound by plasma proteins. The peak drug concentrations, half-life, and area under the concentration-time curve in plasma for 183577 were 3483 ng/ml, 465 min, and 2018 microgram/ml. min, respectively. The peak drug concentration, half-life, and area under the concentration-time curve in plasma for 232759 were 5257 ng/ml, 44 min, and 276 microgram/ml. min, respectively, at the MTD and 2810 ng/ml, 40 min, and 110 microgram/ml. min at one-half the MTD. In all instances of simultaneous measurements, drug concentrations were equal or higher in tissues than they were in plasma. Unlike the plasma and kidney concentrations of 183577, the liver concentrations did not show a declining trend over the 8-h observation period. Declines in plasma, liver, kidney, and tumor levels of 232759 were detected over the 8-h observation period. The sustained high 183577 concentration in liver is believed to be responsible for its prolonged half-life and hepatotoxicity. Evidence for metabolism of the parent drugs was based on the finding of additional peaks on the high-pressure liquid chromatography tracings. Future studies will focus on identification and antitumor studies of these presumed metabolites in hopes of a better understanding of the solid tumor activity profiles and toxic effects of these compounds.

Pharmacokinetics of 9-methoxy-N,N-dimethyl-5-nitropyrazolo [3,4, 5-kl]acridine-2(6H)-propanamine (PZA, PD 115934, NSC 366140) in mice: guidelines for early clinical trials1.

Pharmacokinetic studies that consisted of measuring the plasma drug profile, tissue drug distribution, and elimination in urine and feces were performed in female C57BL/6 x DBA/2 (hereafter called B6D2F1) and male B6D2F1A/2 and C57BL/6 x CH3 (hereafter called B6C3F1) mice following treatment with a 1-h i.v. infusion of the PZA, PD115934 (NSC 366140). This drug is the first of a new class of cytotoxic agents and was selected for clinical trials because of both its broad antitumor activity in vivo against murine solid tumors and human xenografts, and its in vivo toxicity profile that was predictable based on drug dose and schedule of administration. The pharmacokinetic results obtained here in mice have been used to facilitate the dose escalations during the Phase I trial and to determine pharmacokinetic drug exposure targets for its acute and sub-acute toxic effects. Plasma samples from three to four mice per time point were pooled, and then individual tissue samples from the same mice were collected at specified times following treatment. All samples were prepared using solid-phase extraction and assayed using high pressure liquid chromatography. The acute dose-limiting toxicity was neurological and occurred immediately after treatment at 300 mg/m2. The peak plasma level range at the acute maximum tolerated dose was 1040-1283 ng/ml. Thus, peak plasma levels <1000 ng/ml were the acute toxicity target. Variations in the area under the plasma drug concentration x the time curve were observed that did not appear to be related to sex or age. The previously defined subacute dose-limiting toxicity was myelosuppression that occurred at a maximum tolerated dose of 600 mg/m2 (300 mg/m2 x 2) in B6D2F1 females. Thus, the area under the plasma drug concentration x the time curve in B6D2F1 females at this dose (1048 microg/ml x min) was the area under the plasma drug concentration x the time curve target. Drug levels were detected at 60 min following treatment in all tissues examined with a plasma:tissue ratio as high as 1:500. The organs with the highest levels were kidney, pancreas, liver, lung, and brain. Fecal excretion was low (range, 0.04-0.20% of the dose administered) and was not clearly different between males and females. Urinary excretion was higher (range, 5-28% of the dose administered) and did show evidence of sex-related differences, with male urinary drug excretion being higher than female urinary drug excretion. The drug was >/=95% protein bound. Preliminary evidence for drug metabolism was found in urine and feces and will be further explored.

Cytotoxic chemotherapy regimens that increase dose per cycle (dose intensity) by extending daily dosing from 5 consecutive days to 28 consecutive days and beyond.

Dose intensity, defined as dose administered per unit time, has emerged as a potentially important measurement of anticancer drug exposure and determinant of efficacy. There are several strategies for increasing dose intensity, one being a protracted daily dosing strategy without major dose reduction for toxicity. This strategy involves continued therapy during periods of recovery from reversible toxicity, and it inherently challenges our understanding that renewing tissues cannot repopulate (recover) in the continued presence of cytotoxic drug. We have tested this idea directly in a murine preclinical trial. Specifically, we have tested whether acutely myelotoxic doses of gemcitabine (i.p. injection, 6.0 mg/m2/day), acetyldinaline [CI-994; GOE 5549; PD 123 654; 4-acetylamino-N-(2'-aminophenyl)-benzamide, 150 mg/m2/day p.o.], and/or melphalan (i.p. injection, 7.2 mg/m2/day) can be tolerated for 28 consecutive days and whether suppressed bone marrow function recovers despite this protracted daily therapy. The three drugs all caused acute neutropenia and suppression of medullary hematopoiesis. Damage to progenitor populations exposed to acetyldinaline and gemcitabine was not as severe as that caused by melphalan, in which case absolute neutrophil count, mature progenitors (colony-forming unit granulocyte/macrophage), and immature progenitors (colony-forming unit-S) progressively declined to severely depressed levels. Marrow recovery was observed during continued daily treatment with acetyldinaline and gemcitabine but not melphalan, and marrow function completely recovered after finishing the 28-day course. Pharmacology studies proved that protracted therapy causes little, if any, change in cellular drug tolerance or systemic exposure.

The investigational new drug XK469 induces G(2)-M cell cycle arrest by p53-dependent and -independent pathways.

PURPOSE: XK469 (2-[4-(7-chloro-2-quinoxalinyloxy) phenoxy]propionic acid), a synthetic quinoxaline phenoxypropionic acid derivative, has broad activity against murine tumors and is entering Phase I clinical development as a topoisomerase IIbeta inhibitor. This study investigated the underlying molecular mechanism of XK469's effects on the cell cycle. EXPERIMENTAL DESIGN: Growth inhibition, cell cycle arrest, induction of p53 and p21 mRNA and protein, and cdc2 phosphorylation and kinase activity were studied in treated cells from the H460 lung cancer line and p21 and p53 knockout cells of the HCT 116 colon cancer line. RESULTS: XK469 arrested H460 cells at G(2)-M, which was associated with cdc2 phosphorylation and decreased cdc2 kinase activity. Moreover, XK469 stabilized p53 and subsequently increased p21(WAF1/CIP1). Furthermore, HCT116 p21(-/-) cells were less sensitive than wild-type cells to XK469-induced growth inhibition, but p53(+/+) and p53(-/-) cells were equally sensitive despite the absence of p21 induction in the p53(-/-) cells. CONCLUSIONS: When considered with published data, our study suggests a complex mechanism of XK469-mediated anticancer activity involving multiple pathways, including p53-dependent and -independent G(2)-M arrest via inactivation of cdc2-cyclin B1 kinase activity.

Phase I pharmacokinetic study of the novel antitumor agent SR233377.

SR233377 is a novel thioxanthenone analogue that demonstrated solid tumor selectivity in vitro with activity confirmed in vivo against several murine tumors including those of colon, pancreas, and mammary origin. Its primary preclinical dose-limiting toxicities included myelosuppression and neurological toxicity. The neurological toxicity was acute and could be ameliorated in mice when the drug was administered as a 1-h infusion instead of rapid i.v. injection. As a result of its preclinical efficacy profile, SR233377 entered Phase I clinical investigation. The compound was administered i.v. over 2 h on day 1 repeated every 28 days. The starting dose was 33 mg/m2 (one-tenth the mouse LD10). Escalations continued to 445 mg/m2 (six escalations), where dose-limiting toxicity was observed. At this dose, acute ventricular arrhythmias, including one patient with torsades de pointes and transient cardiac arrest, occurred. Because this toxicity might have been related to the plasma peak, the protocol was amended to a 24-h infusion beginning at 225 mg/m2. With this dose, prolongation of the corrected QT interval (QTc) over the pretreatment levels resulted. Because prolonged QTc is a known forerunner to acute ventricular arrhythmias, clinical development of SR233377 was stopped. However, preclinical antitumor and toxicity studies with analogues are underway with hopes of identifying a new clinical candidate with similar antitumor effects that is devoid of cardiac toxic effects.

Phase II study of CI-958 in colorectal cancer.

PURPOSE: We completed a phase II trial of CI-958 (NSC 635371) in patients with advanced colorectal cancer given at a dose of 700 mg/m2 every 21 days. METHODS: All 15 patients had metastatic disease and had been previously treated with one 5-fluorouracil-based regimen in an adjuvant (six) or metastatic (nine) setting. RESULTS: None of the patients treated with CI-958 had an objective response to treatment. Median survival was 4.8 months after the start of treatment. Leukopenia was the major toxicity, but no patient experienced febrile neutropenia. An acute febrile reaction was seen after infusion in four of the first nine patients treated. This was abrogated by pretreatment with dexamethasone in the remaining patients. CONCLUSIONS: CI-958 was not effective at this dose and schedule in patients with previously treated advanced colorectal cancer.

Oxaliplatin in tumors other than colorectal cancer.

Oxaliplatin (Eloxatin) has demonstrated significant activity in a variety of tumor types in addition to colorectal cancer. Several studies have reported on the effectiveness of oxaliplatin as single-agent treatment or in combination with cisplatin (Platinol) or paclitaxel (Taxol) in pretreated advanced ovarian cancer patients, with promising data reported for the combination of oxaliplatin and cisplatin as first-line therapy. Other small studies have shown the activity of single-agent oxaliplatin in anthracycline-resistant metastatic breast cancer and refractory non-Hodgkin's lymphoma. Data have also demonstrated the activity of oxaliplatin in combination with gemcitabine (Gemzar) in advanced pancreatic cancer. In recurrent germ-cell cancer, a "biplatin" regimen of oxaliplatin plus cisplatin was found to be effective salvage therapy. Data from these studies indicate that oxaliplatin is active in both platinum-resistant disease and in tumor types that have previously been unresponsive to platinum treatment. Moreover, it enhances the effect of cisplatin or carboplatin, which is a striking demonstration of differing mechanisms of action. Ongoing and planned trials will evaluate the efficacy of oxaliplatin in other disease settings and combinations.

Phase I study of monoclonal antibody-ricin A chain immunoconjugate Xomazyme-791 in patients with metastatic colon cancer.

The immunoconjugate XMMCO-791/RTA consists of ricin A chain bound to a murine monoclonal antibody MoAb 791T. This monoclonal antibody (MoAb) binds to a glycoprotein of 72 kD, which is expressed on human colorectal carcinoma, ovarian carcinoma, and osteogenic sarcoma. XMMCO-791/RTA was tested in a Phase I trial with proposed dose escalation steps of 0.02, 0.04, 0.15, and 0.2 mg/kg per day. Twelve patients with metastatic colorectal carcinoma were treated at 0.02, 0.03, and 0.04 mg/kg per day dose levels administered over 1 hour on days 1-5. Study-related toxicities were hypotension (6 patients); greater than 10% weight gain (6 patients); peripheral edema (9 patients); fever (4 patients); confusion (3 patients); diarrhea (3 patients); proteinuria, as identified by dipstick (3 patients), greater than 0.6 mg/dl decrease in serum albumin (11 patients); greater than 25% decrease in oncotic pressure (10 patients), and a decrease in ionized calcium (8 patients). Six patients received a second course of treatment. HAMA levels developed in 9 patients and titers increased with number of courses administered. Decreased overall toxicity, in comparison to the first course, was noted, but one patient had an allergic-type response (hypotension, crushing chest pain, diaphoresis) after the test dose of the second course (HAMA level > 10,000 IgG). Life-threatening toxicity in the form of fluid shift, resulting in noncardiac pulmonary edema and third-spacing occurred after course 1 in 1 of 3 patients at the 0.04 mg/kg per day level. No further dose escalation was attempted and no antitumor activity was seen.

Vascular disrupting agents.

It has been well established that a functioning vascular supply is essential for solid tumor growth and metastases. In the absence of a viable vascular network, tumors are unable to grow beyond a few millimeters and therefore remain dormant. Initiation of angiogenesis allows for continued tumor growth and progression. Targeting tumor vasculature, either by inhibiting growth of new tumor blood vessels (antiangiogenic agents) or by destroying the already present tumor vessels (vascular disrupting agents; VDA), is an area of extensive research in the development of new antitumor agents. These two groups differ in their direct physiological target, the type or extent of disease that is likely to be susceptible, and the treatment schedule. VDAs target the established tumor blood vessels, resulting in tumor ischemia and necrosis. These agents show more immediate effects compared to antiangiogenic agents and may have more efficacy against advanced bulky disease. VDAs can be divided into two groups--ligand-bound and small molecule agents. Both VDA groups have demonstrated antitumor effects and tumor core necrosis, but consistently leave a thin rim of viable tumor cells at the periphery of the tumor. More evidence suggests VDAs will have their greatest effect in combination with conventional chemotherapy or other modes of treatment that attack this outer rim of cells.

Targeting the epidermal growth factor receptor.

The epidermal growth factor receptor (EGFR) is a member of the erbB family of tyrosine kinase receptors (RTK). The EGFR is involved in cell proliferation, metastasis and angiogenesis, and is expressed in a large proportion of epithelial tumours. The two main classes of EGFR inhibitors in clinical trials are the RTK inhibitors and the monoclonal antibodies. The clinical development of EGFR inhibitors has introduced new challenges to the design of phase I, II, and III trials. Both classes of agents can be safely administered at doses sufficient to inhibit the EGFR system. Receptor tyrosine kinase inhibitors have been extensively evaluated in non-small-cell lung cancer. In this setting, gefitinib has demonstrated activity in patients who fail initial chemotherapy. Monoclonal antibodies have been developed in combination with cytotoxic chemotherapy in several tumour types, most notably colorectal and head and neck cancer. The preliminary results suggest an increase in response rate and time to progression with the combination of cetuximab and chemotherapy in both disease models. Future issues in the development of EGFR inhibitors include the identification of biologic predictors of response, combination with other targeted agents, and their utilisation in earlier stage malignancies.

Preclinical pharmacokinetic, antitumor and toxicity studies with CI-994 (correction of CL-994) (N-acetyldinaline).

CI-994, a substituted benzamide derivative, is a compound that showed solid tumor selectivity for a variety of solid tumor models compared to L1210 leukemia. Due to its lack of aqueous solubility, it requires oral administration. Female B6D2F1 mice were treated with CI-994 once daily by oral administration of 50 mg/kg for 14 days. Following treatment mice were evaluated for pharmacodynamic effects as well as the pharmacokinetic behavior of CI-994 and the de-acetylated derivative dinaline. Mice samples (plasma, urine, feces) were analyzed using solid phase extraction, reverse phase HPLC and ultraviolet detection. The plasma distribution and elimination half-lives for CI-994 were 51 minutes and 9.4 hours, respectively, on D-1; 31 minutes and 3.4 hours, respectively on D-14. The apparent plasma distribution and elimination half-lives for dinaline were 27 minutes and 2.4 hours, respectively, on D-1; 40 minutes and 7.3 hours, respectively on D-14. The CI-994 AUC on D-1 and D-14 were 2879 and 2407 micrograms/ml x minutes, respectively; while the dinaline AUC on D-1 and D-14 were 87 and 92 micrograms/ml x minutes, respectively. Urinary excretion for CI-994 and dinaline was higher on D-14, while the fecal excretion was the same on both days. The Colon #38 tumor growth in treated mice was reduced to 22% of that observed in the controls by D-19. The levels of all blood cells were reduced in the treated mice when compared to controls and the total WBC was the most affected (median 38%). Recovery to pretreatment levels occurred quickly following treatment cessation. Phase I evaluation of chronic oral administration of CI-994 is currently ongoing.