Interval and ratio reinforcement of a complex sequential operant in pigeons

Pigeons were required to produce exactly four pecks on each of two keys in any order for reinforcement. Correct response sequences were reinforced on either fixed-interval two-minute or fixed-ratio four schedules, with each correct sequence treated as a single response. Each pigeon developed a particular dominant sequence that accounted for more than 80% of all sequences. Sequence stereotypy was relatively unaffected by the temporal properties of the fixed-interval and fixed-ratio schedules. Response time (time from the first response in each sequence to the last) was also relatively unaffected by the temporal properties of the schedules. In contrast, response latency (time from end of one sequence to the beginning of the next) was markedly affected by the schedules. Latencies were long early in the interreinforcement interval and got shorter as the interreinforcement interval progressed. These data suggest that stereotyped response sequences become functional behavioral units, resistant to disruption or alteration by reinforcement variables that ordinarily influence the temporal spacing of individual responses.

The role of the response-reinforcer contingency in negative automaintenance

When a response key is briefly illuminated before a grain reinforcer is presented, key pecking is reliably developed and maintained in pigeons, even if pecking prevents reinforcement (negative automaintenance). This experiment demonstrated that pigeons are sensitive to a negative response-reinforcer contingency, even though it does not eliminate responding. Within individual pigeons, two kinds of trials were compared: red key trials, in which reinforcement was negatively contingent on responding, and white key trials, in which reinforcement was unrelated to responding. Reinforcement frequency in non-contingent trials was yoked to the obtained reinforcement frequency in negatively contingent trials. All eight pigeons pecked substantially more on the non-contingent key than on the negative key, and preferred the non-contingent key to the negative key on occasional "choice" trials where both were presented together. When the stimuli correlated with the two conditions were reversed, the pigeons' behavior also shifted. These response differences are taken as evidence that pigeons are sensitive to the negative response-reinforcer contingency.

The maintenance of key pecking by stimulus-contingent and response-independent food presentation

Three naive pigeons were exposed to a series of two-component multiple schedules of response-independent food presentation. The component schedules were sometimes identical (non-differential procedures) and sometimes different (differential procedures). High rates of key pecking were maintained in all the differential procedures, and pecking decreased substantially in non-differential procedures, even when the frequency of food presentation in non-differential procedures was higher than in differential procedures. It is suggested that the high rates of key pecking were maintained not by adventitious response-reinforcer contingencies, but by differential contingencies between the stimulus (keylight) and food. The role of such contingencies in the phenomenon of behavioral contrast is discussed.

Discrete-trials spaced responding in the pigeon: the dependence of efficient performance on the availability of a stimulus for collateral pecking

Four pigeons were exposed to a discrete-trial schedule in which only responses spaced by at least 6 sec were reinforced. After 45, fifty-trial sessions, they failed to meet the spacing requirement in over 90% of the trials. When an alternative, non-contingent key (pecks on which had no consequence) was illuminated concurrently with the first key, the spacing performance of the three pigeons that pecked the non-contingent key improved so that they were obtaining 75% of the possible reinforcers. These data demonstrated the importance of collateral behavior in mediating spaced performance. It was suggested that pigeons may successfully refrain from responding on the spacing procedure only when another stimulus correlated with reinforcement is available for pecking, and that the form that collateral behavior takes may, in general, be non-arbitrary, and species dependent.

Development of complex, stereotyped behavior in pigeons

A pigeon's peck on one key moved a light down one position in a 5x5 matrix of lights, while a peck on another key moved the light across one position. Reinforcement depended upon the occurrence of four pecks on each key (moving the matrix light from the top left to the bottom right), and a fifth peck on either key ended a trial without food. Though there were 70 different sequences that led to reinforcement, each of 12 pigeons developed a particular, stereotyped sequence which dominated its behavior (Experiment 1). Extinction produced substantial increases in sequence variability (Experiment 2). Removal of the matrix cues disrupted performance, though it partially recovered with extended training (Experiment 3). The pigeons did not master a contingency which required a different sequence on the current trial than on the previous one (Experiment 4), though they were able to learn to emit sequences which began with either left-left or left-right response patterns (Experiment 5). The experiments suggest that contingencies of reinforcement may contribute to the creation of complex units of behavior, and that stereotypy may be a likely consequence of contingent reinforcement.

Discriminative stimulus location as a determinant of positive and negative behavioral contrast in the pigeon

Four pigeons were exposed to a series of two-component multiple schedules of reinforcement that ordinarily yield positive and negative behavioral contrast. The stimuli that signalled the component schedules were sometimes located on the response key and sometimes off. Positive behavioral contrast was observed only when the stimuli were on the key. Negative contrast was observed independent of stimulus location. These data suggest that positive and negative contrast may be causally unrelated, and support an account of contrast in terms of the summation of key pecks that are separately controlled by response-reinforcer and stimulus-reinforcer dependencies.

Behavioral contrast in the pigeon: a study of the duration of key pecking maintained on multiple schedules of reinforcement

Pecks on an operant key were reinforced on either multiple variable-interval variable-interval or multiple variable-interval extinction schedules of reinforcement. The stimuli that signalled the multiple-schedule components were located on a second key (signal key), and a changeover delay prevented reinforcement of signal key-peck-operant key-peck sequences. No behavioral contrast was observed on the operant key, and appreciable responding to the signal key occurred during the variable-interval component of the multiple variable-interval extinction procedure. Peck durations on the signal key were markedly shorter than peck durations on the operant key. Moreover, most responses on the signal key occurred just after the multiple-schedule components changed. These data support an account of behavioral contrast in terms of the summation of pecks that are separately controlled by stimulus-reinforcer and response-reinforcer dependencies, and suggest that the stimulus-reinforcer dependency is responsible primarily for local contrast. In addition, the data suggest that pecks that are controlled by these two dependencies may belong to topographically different classes.

Failure to produce response variability with reinforcement

Two experiments attempted to train pigeons to produce variable response sequences. In the first, naive pigeons were exposed to a procedure requiring four pecks on each of two keys in any order, with a reinforcer delivered only if a given sequence was different from the preceding one. In the second experiment, the same pigeons were exposed to this procedure after having been trained successfully to alternate between two specific response sequences. In neither case did any pigeon produce more than a few different sequences or obtain more than 50% of the possible reinforcers. Stereotyped sequences developed even though stereotypy was not reinforced. It is suggested that reinforcers have both hedonic and informative properties and that the hedonic properties are responsible for sterotyped repetition of reinforced responses, even when stereotypy is negatively related to reinforcer delivery.

Allocation of complex, sequential operants on multiple and concurrent schedules of reinforcement

Pigeons could produce food by pecking exactly four times on each of two keys, in any order. In the first experiment, these response sequences were reinforced on a series of multiple schedules of variable-interval reinforcement. In the second experiment, these response sequences were reinforced on a series of concurrent schedules of reinforcement. In both experiments, highly stereotyped response sequences developed. If these response sequences were treated as individual responses, the resulting data conformed to what is typically reported in studies of multiple and concurrent schedules involving individual responses. For example, behavioral contrast was observed with the multiple schedules, and matching was observed with the concurrent schedules. However, schedule manipulation had no effect on within-sequence characteristics of responses like accuracy, stereotypy, or rate. These data constitute further evidence that response sequences can become functional behavioral units.

Two different kinds of key peck in the pigeon: some properties of responses maintained by negative and positive response-reinforcer contingencies

Pigeons emitted almost exclusively short-duration key pecks (shorter than 20 msec) when on negative automaintenance procedures, in which pecks prevented reinforcement. Peck durations under fixed-interval and fixed-ratio reinforcement schedules were generally two to five times longer than pecks under a negative automaintenance schedule. However, initial key pecks were of short duration, independent of procedure. The frequency of short-duration pecks was insensitive to differential reinforcement, while the frequency of long-duration pecks was sensitive to differential reinforcement. It is proposed that short-duration pecks arise from the pigeon's normal feeding pattern and are directly enhanced by food presentation, while long-duration pecks are controlled by the contingent effects of food presentation. The implications of the existence of two classes of pecks for the functional definition of operants and the separation of phylogenetic and ontogenetic sources of control of key pecking are discussed.

Maintenance of key pecking by response-independent food presentation: the role of the modality of the signal for food

Three pigeons were exposed to a series of procedures in which periods of response-independent food presentation, on a variable-time schedule, alternated with periods in which food was never presented. The stimuli that signalled periods of food availability or non-availability varied from one procedure to the next, and were sometimes key colors, sometimes tones, and sometimes compounds of both. Key pecking was initiated and maintained when key color was a signal for food; key pecking was not initiated when a tone was the signal for food. However, control of key pecking that was already established could be transferred from key color to tone, and subsequently, initiated by the tone. It is suggested that for pigeons, pre-experimental relationships exist among food, visual stimuli, and pecking, and that a similar relationship, which includes auditory stimuli, must be induced in the laboratory.

THE EFFECT OF TEMPERATURE ON THE RATE OF HYDROLYSIS OF TRIGLYCERIDES BY PANCREATIC LIPASE

1. The temperature characteristics for the hydrolysis of various concentrations of tributyrin, trivalerin, tricaproin, triheptylin, and tricaprylin have been determined. 2. The micro values for the hydrolysis of all concentrations of tributyrin by pancreatic lipase, except the most dilute, were found to be constant within the experimental error, 8,500 +/- 1,000. 3. The temperature characteristics for the hydrolysis of trivalerin, tricaproin, triheptylin, and tricaprylin varied from approximately 8,500 +/- 1,000 for the high concentrations to 12,400, 20,000, 22,400, and 23,700 respectively for the most dilute concentration of each. 4. An interpretation of these results was presented.

Extracellular BCL2 proteins are danger-associated molecular patterns that reduce tissue damage in murine models of ischemia-reperfusion injury

Background

Ischemia-reperfusion (I/R) injury contributes to organ dysfunction in a variety of clinical disorders, including myocardial infarction, stroke, organ transplantation, and hemorrhagic shock. Recent investigations have demonstrated that apoptosis as an important mechanism of cell death leading to organ dysfunction following I/R. Intracellular danger-associated molecular patterns (DAMPs) released during cell death can activate cytoprotective responses by engaging receptors of the innate immune system.

Methodology/Principal Findings

Ischemia was induced in the mouse hind limb by tourniquet or in the heart by coronary artery ligation. Reperfusion injury of skeletal or cardiac muscle was markedly reduced by intraperitoneal or subcutaneous injection of recombinant human (rh)BCL2 protein or rhBCL2-related protein A1 (BCL2A1) (50 ng/g) given prior to ischemia or at the time of reperfusion. The cytoprotective activity of extracellular rhBCL2 or rhBCL2A1 protein was mapped to the BH4 domain, as treatment with a mutant BCL2 protein lacking the BH4 domain was not protective, whereas peptides derived from the BH4 domain of BCL2 or the BH4-like domain of BCL2A1 were. Protection by extracellular rhBCL2 or rhBCL2A1 was associated with a reduction in apoptosis in skeletal and cardiac muscle following I/R, concomitant with increased expression of endogenous mouse BCL2 (mBCL2) protein. Notably, treatment with rhBCL2A1 protein did not protect mice deficient in toll-like receptor-2 (TLR2) or the adaptor protein, myeloid differentiation factor-88 (MyD88).

Conclusions/Significance

Treatment with cytokine-like doses of rhBCL2 or rhBCL2A1 protein or BH4-domain peptides reduces apoptosis and tissue injury following I/R by a TLR2-MyD88-dependent mechanism. These findings establish a novel extracellular cytoprotective activity of BCL2 BH4-domain proteins as potent cytoprotective DAMPs.

Retinal blood vessel width measured on color fundus photographs by image analysis

The purpose of this paper was to develop a technique using computerized image analysis to measure the width of retinal arteries and veins on color fundus photographs. The width of the retinal vessel was determined from digitized fundus photographs by programs based on edge detection and boundary tracing. The average vessel width was determined at different distances or eccentricities from the center of the optic disc and using various lengths of vessel segment. Measurements of superior and inferior temporal vessel width for 20 eyes by 2 operators showed that about 75% of the measurements could be obtained without the use of plan points. The average percent coefficient of variation of the measurements was 2.17% for 3 measurements of each vessel. This technique provides a reproducible and objective method for obtaining the following parameters: the edges of the vessel, the length of the vessel segment to be measured, location of the measurement along the vessel and subsequent retinal vessel width. This technique is readily suitable for application to clinical studies particularly clinical trials.

Decrease of optic disc cupping and pallor of ocular hypertensives with timolol therapy

PURPOSE

The purpose of this study was to determine whether timolol drops compared to placebo drops had a significant effect on optic disc cupping and pallor in ocular hypertensives.

METHODS

Thirty-seven ocular hypertensives were randomly assigned to placebo or 0.5% timolol drops to both eyes in a double masked clinical trial. Measurements of ocular pressure and photographs of the optic disc for cupping by photogrammetry and pallor by computerized image analysis were made at about 3 month intervals, for 18 to 24 months of follow-up.

RESULTS

None of the subjects developed visual field loss when tested with the Goldmann perimeter by kinetic and static means at six month intervals. Subjects treated with timolol developed a significant decrease in ocular pressure and a significant decrease in optic disc cupping with a smaller decrease in pallor compared to subject treated with placebo. Multivariate analyses indicated that the decrease of optic disc cupping and pallor was not associated with the ocular pressure on treatment or the decrease in ocular pressure during the trial.

CONCLUSION

Timolol treatment was associated with a decrease in optic disc cupping and pallor. The effect of timolol appears to be related to mechanisms other than the decrease in ocular pressure.

Increase of retinal nerve fiber layer thickness in ocular hypertensives with timolol therapy

PURPOSE

The purpose of this study was to determine whether timolol drops compared to placebo drops had a significant effect on retinal nerve fiber layer thickness in ocular hypertensives.

METHODS

Thirty-seven ocular hypertensives were randomly assigned to receive placebo or 0.5% timolol drops to both eyes for 18 to 24 months in a double masked clinical trial. Measurements of ocular pressure and photographs of retinal nerve fiber layer using stereophotogrammetric techniques were made at about 3 month intervals for 18 to 24 months of follow-up.

RESULTS

None of the subjects developed visual field loss when tested with the Goldmann perimeter by kinetic and static means at six month intervals. Subjects treated with timolol had a significant decrease in ocular pressure and developed a significant increase in retinal nerve fiber layer thickness compared to subjects treated with placebo. Multivariate analyses indicated that the increase of retinal nerve layer thickness was not associated either with the ocular pressure on treatment or the decrease in ocular pressure on treatment.

CONCLUSION

Timolol treatment was associated with an increase of retinal nerve fiber thickness. The effect of timolol appears to be related to mechanisms other than the decrease in ocular pressure.

Increase of retinal vessel width in ocular hypertensives with timolol therapy

PURPOSE

The purpose of this study was to determine whether timolol drops compared to placebo drops had a significant effect on retinal vessel width in ocular hypertensives.

METHODS

Thirty-seven ocular hypertensives were randomly assigned to receive placebo or 0.5% timolol drops to both eyes for 18 to 24 months in a double masked clinical trial. Measurements of ocular pressure and retinal vessel width by computerized image analysis from fundus photographs were made at about 3 month intervals for 18 to 24 months of follow-up.

RESULTS

None of the subjects developed visual field loss when tested with the Goldmann perimeter by kinetic and static means at six month intervals. Subjects treated with the placebo showed no change in ocular pressure and a significant decrease in retinal vessel width over time especially in the right eye. Subjects treated with timolol had an increase in retinal vessel width compared to the placebo group significant especially for the superior temporal vein. Multivariate analyses indicated that the increase of retinal vessel width was not associated mainly with the ocular pressure on treatment or decrease in ocular pressure on treatment.

CONCLUSION

Timolol treatment was associated with an increase of retinal vessel width. The effect of timolol appears to be related primarily to mechanisms other than the decrease in ocular pressure.

Phase I dose escalation trial (ARQ 197–111) evaluating combination of selective c-Met inhibitor ARQ 197 and erlotinib

3549

Background: ARQ197 (A) is a selective, non-ATP competitive inhibitor of c-Met, a receptor tyrosine kinase implicated in tumor cell migration, invasion, and proliferation. Phase I data for ARQ 197 monotherapy is previously reported. Recent evidence suggests c-Met promotes resistance to EGFR-inhibition by driving ERBB3 (HER3)-dependent PI3K activation. Dual EGFR-Met inhibition is now proposed as a strategy for overcoming resistance to EGFR-inhibition. Methods: Patients (pts) were enrolled in a sequential-cohort dose-escalation trial seeking to define safety, tolerability, pharmacokinetics (PK), and preliminary anti-tumor activity of A in combination with 150 mg daily oral erlotinib (E). Oral A was administered at escalating doses of 120, 240, and 360 mg bid. Intra-patient dose escalation was allowed in the absence of dose-limiting toxicity (DLT) through 1 cycle of therapy (21 days). Results: 25 pts (10 F/15 M; mean 60.5 yrs) received EA combination with starting A dose of 120 (8 pts), 240 (4 pts), and 360 (13 pts) mg bid. PK data reveal linear kinetics through 360 bid and no evidence of drug-drug interaction. Adverse events (AEs) considered related to combination therapy were reported in 13 (52%) of pts incl.sinus bradycardia (5 pts), fatigue (5 pts), rash (4 pts), itching (3 pts), and diarrhea (3 pts). 2 pts experienced related serious AEs incl. neutropenia (360 bid) and sinus bradycardia (240 bid). 1 death occurring on-study was considered unrelated to study drug. 9/10 evaluable pts demonstrated disease stabilization (SD) as their best RECIST response (5.9–27.1+ wks). Tumor regressions (2.3%-19.4%) were observed in 4/10 evaluable pts. Of note, 3/3 evaluable pts with NSCLC achieved SD for durations (14–32 wks) exceeding median PFS in BR.21 (9.7 wks). Conclusions: Continuous therapy with EA combination appears well tolerated and without drug-drug interaction. While no formal MTD was identified, a phase 2 combination dose (R2PD) of 360 mg bid A + 150 mg daily E is recommended. This RP2D is currently being investigated in an ongoing randomized trial comparing EA to E monotherapy in 2nd/3rd line NSCLC.

[Table: see text]

Interferon protects mice against inhalation anthrax

Interferons (IFNs) play a role in innate immunity during many viral, bacterial, and protozoal infections. With the increasing threat of bioterrorist attacks with Bacillus anthracis, its high lethality, and the limited effectiveness of antibiotics, alternative treatments are being studied. Antibodies to protective antigen (PA) are promising, as is IFN. During many bacterial infections, production of and protection by IFNs has been reported, including B. anthracis in vitro. In vivo, we find that (1) the type I IFN inducer, Poly-ICLC, strongly and rapidly protects mice; (2) the protection is IFN-mediated since recombinant murine IFN-beta can protect, and protection by Poly-ICLC is abrogated in IFN type I receptor knockout mice. The greatest protection by Poly-ICLC was conferred by intranasal treatment. A delay in death was observed with the intramuscular route alone, but was not significant. Together, the results suggest the IFN defense could protect mice, up to 60%, against lethal inhalational anthrax, and thus have important medical implications for therapy of human anthrax.

A novel stone retrieval basket for more efficient lithotripsy procedures

This paper presents the development of an improved stone retrieval device that uses a newly designed cage of Nitinol wires encompassing a mesh basket made of a material that is laser resistant. Current methods to extract large stones involve imaging, using a laser to fragment the stones and then using existing cage-like baskets to trap the fragments individually and extracting them one at a time. These procedures are tedious, and may result in leaving some fragments behind that can reform causing the need for another procedure. The device presented in this paper will have a mesh-like sack which will consist of a laser resistant material of polytetrafluoroethylene (PTFE) enclosed within a newly designed Nitinol cage. Two alternate designs are provided for the cage in this paper. The handle of the device is revised to allow for a 3 Fr (1 mm) opening such that a laser's fiber optic cable can enter the device. Using this device a laser can be used to fragment the stone, and all the fragments are retained in the basket in both the design options. The basket can then be retracted allowing for the retrieval of all the fragments in one shot. The stone retrieval basket presented in this paper will significantly improve the efficiency and effectiveness of lithotripsy procedures for removal of large kidney and biliary tract stones.

Acute promyelocytic leukaemia and acquired alpha-2-plasmin inhibitor deficiency: a retrospective look at the use of epsilon-aminocaproic acid (Amicar) in 30 patients

Bleeding diathesis and a hyper-fibrinolytic state often accompany a diagnosis of Acute Promyelocytic Leukaemia (APML). This complication can have grave effects if not successfully treated, with a 10-20% incidence of haemorrhagic death. We hypothesized that alpha-2-antiplasmin levels would correlate with the risk for bleeding, and that administration of epsilon-aminocaproic acid (EACA) would attenuate that risk. To assess this, we conducted a retrospective chart review analyzing 30 APML patients, 17 of whom were treated with EACA. Thirty patients were treated, 21 with primary induction therapy. Patients with low alpha-2-antiplasmin levels were treated with a coagulopathy protocol consisting of low-dose heparin, EACA and blood product support. Seventeen patients (57%) developed haemorrhagic complications during their treatment. The presence and grade of haemorrhage appeared to be associated with the alpha-2-antiplasmin level. There were no grade IV haemorrhages or episodes of haemorrhagic death. One episode of central venous catheter associated thromboembolism and three deaths from infection during chemotherapy were observed. alpha-2-Antiplasmin levels are a reliable surrogate for fibrinolysis and haemorrhagic risk in patients with APML. Treatment with EACA is a rational way to pharmacologically inhibit fibrinolysis, is associated with a low incidence of severe haemorrhagic events, and appears to be safe with a low risk of thrombosis. Randomized clinical trials further assessing the efficacy and potential toxicity of EACA in inhibiting fibrinolysis in patients with APML are needed.

Cyclin-dependent kinase inhibitors block leukocyte adhesion and migration

Leukocyte trafficking is a tightly regulated process essential for an appropriate inflammatory response. We now report a new adhesion pathway that allows unstimulated leukocytes to adhere to and migrate through exposed endothelial matrix or high-density ligand, a process we have termed ligand-induced adhesion. This ligand-induced adhesion is integrin mediated, but in contrast to phorbol ester-stimulated adhesion, it is not dependent on the small GTPase Rap-1 activity. Instead, we show a critical role for cyclin-dependent kinase (Cdk) 4 in ligand-induced adhesion by three independent lines of evidence: inhibition by pharmacological inhibitors of Cdk, inhibition by dominant-negative construct of Cdk4, and inhibition by Cdk4 small interfering RNA. The major substrate of Cdk4, Rb, is not required for ligand-induced adhesion, suggesting the involvement of a novel Cdk4 substrate. We also demonstrate that Cdk4(-/-) mice have impaired recruitment of lymphocytes to the lung following injury. The finding that Cdk inhibitors can block leukocyte adhesion and migration may expand the clinical indications for this emerging class of therapeutics.

Organic arsenic in patients (pts) with advanced solid tumors: Phase-1 results of zio-101 (s-dimethylarsino-glutathione)

3554

Background: ZIO-101(S-dimethylarsino-glutathione), a novel organic arsenic, is active against multiple cancers in vitro and in animal models. Anti-cancer activity is multifaceted and is mediated by disrupted mitochondrial function, increased reactive oxygen species (ROS) production, modified signal transduction and anti-angiogenesis. Methods: Phase-1 dose finding study to determine maximum tolerated dose (MTD), dose-limiting toxicity (DLT), pharmacokinetics (PK), and toxicities of ZIO-101 in patients with advanced solid tumors. Results: 34 pts (18 M/16 F) received 78–588 mg/m2/d IV for 5 consecutive days every 4 weeks. Median age was 61 (range, 42–79 y). Median N prior regimens was 3 (1–5). Pts had colorectal (N=17; 12 evaluable), renal (N=4), lung (N=3), melanoma (N=2), pancreas (N=2) and others (N=6). Median N of cycles was 2 (range, 1–12). MTD is 420 mg/m2/d and DLT was transient confusion, and ataxia. Fatigue, nausea and emesis were = grade-2. ZIO-101 was otherwise well-tolerated: There are no hematological toxicities and no QTc- prolongation. Five patients had stable-disease 4–12 mo (colorectal [N=3], renal [N=2],). PK studies at 420 mg/m2/d: tmax = 1 h (SD + 0.9), Cmax = 1.06 μg/L (SD ± 0.07 μg/mL), t1/2 = 17.8 h (SD ± 1.4 h) and AUC0- 8 = 25.9 mg·h/L (SD ± 0.8mg.h/L). 1 pt had complete resolution of a brain metastasis (renal) and 1 patient had a substantial decrease of a liver metastasis (pancreas). Conclusions: ZIO-101 was well tolerated. MTD is 420 mg/m2/d and DLT is transient confusion and ataxia. There was observed clinical benefit in five patients. Expansion cohort is ongoing to further test toxicities and antitumor activity. Phase II studies are ongoing.

[Table: see text]

ZIO-101 (S-dimethylarsino-glutathione): Phase I/II trials in advanced/progressive multiple myeloma

8109

Background: ZIO-101(S-dimethylarsino-glutathione), a novel organic arsenic, is active against multiple cancers including myeloma in vitro and in animal models. In vitro, it is active at low concentrations in cancers resistant to arsenic trioxide. Anti-cancer activity is multifaceted and is mediated by disrupted mitochondrial function, increased reactive oxygen species (ROS) production, modified signal transduction and anti-angiogenesis. Methods: (1) Phase I/II study to determine maximum tolerated dose (MTD), dose- limiting toxicity (DLT), safety-profile and preliminary efficacy in patients with advanced/progressive myeloma receiving ZIO-101 daily for 5 consecutive d every 4 w; (2) comparison of this schedule at MTD with a schedule of 420 mg/me2/d twice/w for 3 w every 4 w. Results: (1) phase I/ II: 19 patients have been treated so far. Median age is 61 y (range, 41–84 y). Median N prior therapies was 8 (range, 4–10). ZIO-101 was well-tolerated; MTD was 420 mg/me2/d for the 5 d schedule, and DLT was transient confusion /ataxia. No clinically- important biochemical, bone marrow, or cardiac toxicities were seen and there was neither neuropathy nor QTc-prolongation. Pain during peripheral infusion was reported in some patients. Anemia was the only adverse event = grade-3 in 25% of subjects. 6 of 14 evaluable subjects had stable disease (SD) =8 w and 2, SD > 6 mo. Accrual to the phase II portion continues. Conclusions: ZIO-101 was well- tolerated. In the daily for 5 consecutive d every 4 w schedule, the MTD is 420 mg/me2/d and DLT, transient confusion /ataxia. There was SD in 43% of patients with advanced/progressive myeloma, of whom half are beyond 6 months. Accrual into the phase II part of this study continues.

No significant financial relationships to disclose.

Phase I and pharmacological study of orally administered indibulin in advanced solid tumors

2565

Background: Indibulin (ZIO-301/D-24851) (N-(pyridin-4-yl)-[1-(4-chlorbenzyl)-indol-3-yl]-glyoxyl-amid) a novel, oral, synthetic, anti-mitotic drug is widely active against human tumor cell lines and xenografts, including multidrug resistant and taxane refractory tumors. Indibulin destabilizes microtubule polymerization; its tubulin binding site is distinct from taxanes and vinca alkaloids. In preclinical studies indibulin lacks neurotoxicity typically associated with other tubulin binding drugs. Methods: Phase I study to evaluate safety, pharmacokinetics (PK), maximum tolerated dose (MTD) and dose limiting toxicity (DLT) in patients with advanced solid tumors. Initial dosing was in lactic acid drinking solution, which later was converted to a capsule formulation. Administration was po daily for 14 consecutive days at 21 day intervals at pre-determined dose increases between cohorts. Results: 31 patients (20 M, 11F) with advanced refractory cancers were treated; 14 received 20–80 mg/dose po in lactic acid solution and 17 po capsules 100–600 mg/dose. Median age was 60 y (29–72 y); median number of prior therapies was 4 (1–8); ECOG PS = 2. Median number of cycles was 2 (1–14). Patients continued on study until disease progression or significant toxicity. DLT for solution was nausea and emesis, ascribed to lactic acid. To date, no MTD or DLT observed with oral capsules at 600 mg daily; dose escalation continues using a twice daily schedule. No neurotoxicity has been observed. There was a disproportionate increase of the AUC with dose, with declining AUC corrected for dose starting at the 250 mg dose-level. The terminal half-life at the 600 mg dose was 25.2 ± 2.4 h. Prolonged disease stabilization was seen in 2 adenoid cystic carcinoma patients for 3 and 14 months and in one prostate cancer patient for 5 months. The latter patient went off study after 5 months due to liver function disorder (ALT CTC grade 2 and AST grade 3). Conclusions: Indibulin was well tolerated at doses showing preliminary clinical activity. Target plasma concentrations above the IC50 have been achieved. Dose escalation twice daily continues. Prolonged disease stabilization was noted in adenoid cystic carcinoma and prostate cancer.

[Table: see text]

Loss of AP-2alpha results in deregulation of E-cadherin and MMP-9 and an increase in tumorigenicity of colon cancer cells in vivo

Activator protein-2 (AP-2) is a transcription factor that regulates proliferation and differentiation in mammalian cells and has been implicated in the acquisition of the metastatic phenotype in several types of cancer. Herein, we examine the role of AP-2alpha in colon cancer progression. We provide evidence for the lack of AP-2alpha expression in the late stages of colon cancer cells. Re-expression of the AP-2alpha gene in the AP-2alpha-negative SW480 colon cancer cells suppressed their tumorigenicity following orthotopic injection into the cecal wall of nude mice. The inhibition of tumor growth could be attributed to the increased expression of E-cadherin and decreased expression and activity of matrix-metalloproteinase-9 (MMP-9) in the transfected cells, as well as a substantial loss of their in vitro invasive properties. Conversely, targeting constitutive expression of AP-2alpha in AP-2-positive KM12C colon cancer cells with small interfering RNA resulted in an increase in their invasive potential, downregulation of E-cadherin and increased expression of MMP-9. In SW480 cells, re-expression of AP-2alpha resulted in a fourfold increase in the activity of E-cadherin promoter, and a 5-14-fold decrease in the activity of MMP-9 promoter, indicating transcriptional regulation of these genes by AP-2alpha. Chromatin immunoprecipitation assay showed that re-expressed AP-2alpha directly binds to the promoter of E-cadherin, where it has been previously reported to act as a transcriptional activator. Furthermore, chromatin immunoprecipitation assay revealed AP-2alpha binding to the MMP-9 promoter, which ensued by decreased binding of transcription factor Sp-1 and changes in the recruitment of transcription factors to a distal AP-1 element, thus, contributing to the overall downregulation of MMP-9 promoter activity. Collectively, our data provide evidence that AP-2alpha acts as a tumor suppressor gene in colon cancer..

Mass vaccination for annual and pandemic influenza

Influenza virus causes annual epidemics and occasional pandemics. Frequent mutations in circulating influenza strains ("antigenic drift") result in the need for annual vaccination. More than two-thirds of persons in the U.S. are recommended for annual vaccination. Because influenza vaccine is available seasonally, mass vaccination strategies are well suited to its delivery. Although doctors offices are the most frequent setting for influenza vaccination overall, workplaces, clinics, and community sites (retail stores and pharmacies) also are common vaccination settings. Influenza vaccination also is delivered in mass vaccination clinics to health care workers and military personnel. Universal influenza vaccination, which has been recommended as a strategy to improve prevention by increasing vaccination coverage and providing indirect protection of adults by decreasing infection and transmission among children, would require expanded use of mass vaccination, for example in schools, as well as in the community. Influenza pandemics occur when a new influenza A subtype is introduced into the population ("antigenic shift"). Most or all of the population is susceptible to the pandemic virus and two doses of vaccine may be needed for protection. U.S. pandemic preparedness and response plans indicate that the entire population should be vaccinated beginning with defined priority groups including those who provide essential services including healthcare and those at highest risk of severe illness and death. Pandemic influenza vaccination will occur primarily through the public sector in mass clinic settings. Vaccination program planning must consider issues including coordination, staffing, clinic location and lay-out, security, record keeping, and communications. Exercising vaccination clinics is important for preparedness and can be done in the context of annual influenza vaccination.

Sorafenib in advanced melanoma: a Phase II randomised discontinuation trial analysis

The effects of sorafenib – an oral multikinase inhibitor targeting the tumour and tumour vasculature – were evaluated in patients with advanced melanoma enrolled in a large multidisease Phase II randomised discontinuation trial (RDT). Enrolled patients received a 12-week run-in of sorafenib 400 mg twice daily (b.i.d.). Patients with changes in bi-dimensional tumour measurements <25% from baseline were then randomised to sorafenib or placebo for a further 12 weeks (ie to week 24). Patients with ⩾25% tumour shrinkage after the run-in continued on open-label sorafenib, whereas those with ⩾25% tumour growth discontinued treatment. This analysis focussed on secondary RDT end points: changes in bi-dimensional tumour measurements from baseline after 12 weeks and overall tumour responses (WHO criteria) at week 24, progression-free survival (PFS), safety and biomarkers (BRAF, KRAS and NRAS mutational status). Of 37 melanoma patients treated during the run-in phase, 34 were evaluable for response: one had ⩾25% tumour shrinkage and remained on open-label sorafenib; six (16%) had <25% tumour growth and were randomised (placebo, n=3; sorafenib, n=3); and 27 had ⩾25% tumour growth and discontinued. All three randomised sorafenib patients progressed by week 24; one remained on sorafenib for symptomatic relief. All three placebo patients progressed by week-24 and were re-started on sorafenib; one experienced disease re-stabilisation. Overall, the confirmed best responses for each of the 37 melanoma patients who received sorafenib were 19% stable disease (SD) (ie n=1 open-label; n=6 randomised), 62% (n=23) progressive disease (PD) and 19% (n=7) unevaluable. The overall median PFS was 11 weeks. The six randomised patients with SD had overall PFS values ranging from 16 to 34 weeks. The most common drug-related adverse events were dermatological (eg rash/desquamation, 51%; hand-foot skin reaction, 35%). There was no relationship between V600E BRAF status and disease stability. DNA was extracted from the biopsies of 17/22 patients. Six had V600E-positive tumours (n=4 had PD; n=1 had SD; n=1 unevaluable for response), and 11 had tumours containing wild-type BRAF (n=9 PD; n=1 SD; n=1 unevaluable for response). In conclusion, sorafenib is well tolerated but has little or no antitumour activity in advanced melanoma patients as a single agent at the dose evaluated (400 mg b.i.d.). Ongoing trials in advanced melanoma are evaluating sorafenib combination therapies.

Randomized phase III trial of sorafenib in advanced renal cell carcinoma (RCC): Impact of crossover on survival

4524

Background: Sorafenib was approved for advanced RCC in the USA December 2005. A Phase III randomized double-blind, placebo-controlled trial demonstrated an estimated 39% improvement in survival for patients receiving sorafenib versus placebo (HR= 0.72, p = 0.018) (ECCO 2005). These data supported independently reviewed doubling of PFS to 24 weeks in RCC patients receiving sorafenib compared with placebo (12 weeks) (p < 0.000001) (ASCO 2005). Based on the statistical significance and magnitude of PFS benefit, patients were unblinded and placebo patients allowed to crossover to sorafenib in April 2005. A prospectively planned interim OS analysis reflecting impact of crossover of placebo patients is presented. Methods: OS data up to November 30, 2005, were analyzed in this interim analysis using a stratified log-rank test comparing the two treatment groups. In order to examine the effect of crossover on OS, a secondary analysis was performed censoring data from patients randomized to placebo at June 30, 2005. Results: A total of 903 patients were randomized (451 to sorafenib, 452 to placebo) and >200 placebo patients crossed over to sorafenib. Baseline characteristics were similar between treatment arms. There were 367 deaths. The median OS was 19.3 months for sorafenib versus 15.9 months for placebo (HR = 0.77; 95% CI 0.63, 0.95; p = 0.015); although this did not attain the level of significance specified for the interim analysis (α = 0.009), a continued favorable trend in survival benefit was observed. With censoring of crossover data, the median OS was 19.3 months for sorafenib versus 14.3 months for placebo (HR = 0.74, 95% CI 0.58, 0.93; p = 0.010). Conclusion: Sorafenib is the first novel, oral approved treatment for advanced RCC in more than a decade. Previous information on the effect of crossover on OS in randomized oncology studies is limited. The lower HR observed after censoring placebo patients crossed over to sorafenib suggests a continued beneficial effect of sorafenib. Final results await more mature data.

[Table: see text]

Burden of illness analysis of renal cell carcinoma

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Background: There were over 36,000 new cases of kidney cancer reported in the US in 2004, the most common being renal cell carcinoma (RCC). RCC patients have limited treatment options and low survival rates, particularly for advanced-staged patients. Despite the growing importance of RCC, data on its economic burden are limited. Methods: A prevalence-based approach was used to estimate the aggregate annual cost burden from a societal perspective, including costs of medical treatment and lost productivity, due to RCC in the U.S. Key relationships represented in the model include the annual number of patients treated for RCC by age group and cancer stage; utilization of cancer specific treatments; unit costs of these treatments; work-days missed by these patients, and wage rates. Data sources included the linked Surveillance, Epidemiology, and End Results (SEER)-Medicare database, the Bureau of Labor Statistics, and the published literature. Results: The annual prevalence of RCC in the US was estimated to be 109,500 cases. The associated annual burden of RCC (US $2005) was approximately $4.8 billion ($43,749 per patient). Healthcare costs and lost productivity accounted for 84.9% ($4.1 billion) and 15.1% ($726 million) of the total, respectively. Reflecting its higher prevalence, the total cost associated with localized RCC accounted for the greatest share (78.2%) followed by regional, distant and unstaged RCC, which accounted for 18.3%, 2.8% and 0.7%, respectively. Sensitivity analyses resulted in a range in the estimated annual burden from $3.9 to $5.2 billion. Focusing only on newly diagnosed RCC cases (approximately 25,000 per year), the annual burden was estimated at $1.5 billion, with a per-patient cost of $62,340. Conclusions: The economic burden of RCC in the US is substantial. New therapies for RCC have the potential to yield considerable economic and societal benefits.

[Table: see text]

Anti-proliferative effects of sorafenib in clear cell renal cell carcinoma (CCRCC) cell lines: Relationship to von Hippel Lindau protein (pVHL) expression and hypoxia

4601

Background: Sorafenib, a multikinase inhibitor targeting raf kinase and several receptor tyrosine kinases including VEGFR-2 and PDGFR, has demonstrated clinical activity in the treatment of metastatic CCRCC. To further characterize the molecular basis of response to this agent, we tested the functional role of pVHL and hypoxia in the anti-tumor activity of sorafenib in a panel of CCRCC cell lines. Methods: CCRCC cell lines CAKI-1 (wild-type pVHL), CAKI-2 (mutant VHL) and the isogenic pair, 786–0-neo (vector control) and 786–0-VHL (pVHL expressing) cells were treated with sorafenib (2.5 - 20 μM) for 24 - 96 hours at 37°C in a atmosphere of either normoxia (21% oxygen) or hypoxia (1% oxygen), 5% carbon dioxide and remainder nitrogen. Gene expression analysis of control and sorafenib treated CCRCC cell lines was carried out using a custom cancer cDNA array containing probes to 9240 cDNA clones corresponding to 4900 Unigenes or unclustered ESTs relevant to cancer or kidney development. Results: Anti-proliferative effects of sorafenib were both concentration and time of treatment dependent; the IC50 of sorafenib (inhibitory concentration for 50% cell kill) ranged from 7.5-10 μM and required continuous treatment for at least 48-72 hours for maximal cell kill. In contrast to CAKI-2 and 786–0-neo cells harboring mutant VHL, both CAKI-1 and 786–0-VHL cells expressing wild type VHL were ∼2-fold more resistant to the anti-proliferative effects of sorfaenib when treated under hypoxic conditions. No difference in resistance was observed under normoxic conditions. In contrast to 786–0-neo cells, there were ∼40 genes overexpressed (>5-fold) under hypoxia in control 786–0-VHL cells, that were predominantly related to anti-apoptosis (e.g. bcl2-associated athanogene) or angiogenesis (e.g. PDGF beta). Bcl2-associated athanogene and PDGF beta were down regulated >2-fold in hypoxia with sorafenib treatment. Conclusions: CCRCC with wild type VHL under hypoxic conditions can promote overexpression of anti-apoptotic and angiogenesis genes that attenuate the anti-proliferative effects of sorafenib. pVHL and hypoxia related genes may be important biomarkers for assessing the clinical efficacy of sorafenib in CCRCC.

[Table: see text]

Randomized phase II trial of the multi-kinase inhibitor sorafenib versus interferon (IFN) in treatment-naïve patients with metastatic renal cell carcinoma (mRCC)

4501

Background: Sorafenib, an oral multi-kinase inhibitor that targets tumor growth and vascularization, significantly prolonged PFS in a Phase III trial with previously treated mRCC patients. This randomized Phase II trial investigated the efficacy and tolerability of sorafenib compared with IFN in first-line therapy of patients with clear-cell RCC. Methods: Untreated patients with mRCC were stratified by MSKCC prognostic score and randomized to receive continuous oral sorafenib 400 mg bid or IFN 9 million units tiw, with an option of dose escalation (600 mg bid sorafenib) or crossover from IFN to sorafenib upon disease progression. The study assessed PFS at 99 events as primary objective, best response (RECIST), overall survival, health-related quality of life, and adverse events (AEs). Results: Baseline characteristics of 188 patients (sorafenib n=97; IFN n = 91) were: median age 62.0 years; MSKCC score: 57% low, 41% intermediate, 1% high; prior nephrectomy: 82%; ECOG 0:1, 55.3%:44.7%. As of January 6, 2006, PFS events have been reported for 64 (34%) patients. Preliminary data showed drug-related AEs of any severity (sorafenib vs IFN) in 50.5% vs 51.6% of patients (≥grade 3: 8.2% vs 11.0%), including diarrhea (24.7% vs 5.5%), fatigue (14.4% vs 20.9%), fever (2.1% vs 18.7%), hypertension (13.4% vs 0%), nausea (5.2% vs 13.2%), flu-like syndrome (1.0% vs 6.6%), hand-foot skin reaction (6.2% vs 0%), and rash/desquamation (4.1% vs 0%). Drug-related metabolic/laboratory abnormalities at grade 3 (no grade 4) comprised hypophosphatemia (21.7% vs. 0%), lipase elevation (5.6% vs. 11.1%), anemia (0% vs. 5.3%) and hypoalbuminemia (0% vs. 3.6%). Five patients receiving IFN withdrew from treatment due to AEs, whereas only one patient withdrew from sorafenib. Conclusions: Sorafenib was generally well tolerated in RCC patients in the first-line setting, with relatively infrequent drug-related AEs ≥grade 3. Full PFS data will be presented at the meeting.

[Table: see text]

Results of a Phase I trial of sorafenib (BAY 43-9006) in combination with doxorubicin in patients with refractory solid tumors

BACKGROUND

Sorafenib (BAY 43-9006), a novel, oral multi-kinase inhibitor, blocks serine/threonine and receptor tyrosine kinases in the tumor and vasculature. Sorafenib demonstrated single-agent activity in Phase I studies, and was tolerated and inhibited tumor growth in combination with doxorubicin in preclinical studies. This Phase I dose-escalation study determined the safety, pharmacokinetics and efficacy of sorafenib plus doxorubicin.

PATIENTS AND METHODS

Thirty-four patients with refractory, solid tumors received doxorubicin 60 mg/m(2) on Day 1 of 3-week cycles, and oral sorafenib from Day 4 of Cycle 1 at 100, 200 or 400 mg bid.

RESULTS

Common drug-related adverse events were neutropenia (56%), hand-foot skin reaction (44%), stomatitis (32%), and diarrhea (32%). The maximum tolerated dose was not reached. One patient with pleural mesothelioma achieved a partial response (modified WHO criteria) and remained on therapy for 39.7 weeks. Fifteen patients (48%) achieved stable disease for >/=12 weeks. Doxorubicin exposure increased moderately with sorafenib 400 mg bid. The pharmacokinetics of sorafenib and doxorubicinol were not affected.

CONCLUSION

Sorafenib 400 mg bid plus doxorubicin 60 mg/m(2) was well tolerated. The increased doxorubicin exposure with sorafenib 400 mg bid did not result in significantly increased toxicity; low patient numbers make the clinical significance of this unclear. These promising efficacy results justify further clinical investigation.

A phase III randomized trial of BAY 12-9566 (tanomastat) as maintenance therapy in patients with advanced ovarian cancer responsive to primary surgery and paclitaxel/platinum containing chemotherapy: a National Cancer Institute of Canada Clinical Trials Group Study

OBJECTIVE

BAY 12-9566 (tanomastat) is a biphenyl matrix metalloprotease inhibitor (MMPI) with antiangiogenic and antimetastatic properties in vivo. The objective of the study was to determine whether the addition of BAY 12-9566 after optimal response to chemotherapy could improve time to progression (TTP).

PATIENTS AND METHODS

Patients enrolled in the study had received 6-9 cycles of platinum/paclitaxel containing chemotherapy for stage III or IV ovarian carcinoma, with a response of no evidence of disease, or complete or partial response with residual disease < 2 cm. Patients were then randomized to BAY 12-9566 800 mg p.o. b.i.d. or placebo. The primary endpoint was progression-free survival (PFS); secondary endpoints were quality of life, toxicity, changes in CA 125 levels, response, and overall survival (OS). The total planned sample size was 730.

RESULTS

The study was closed after 243 patients had been randomized because of Bayer's decision to close all ongoing trials due to negative results from other phase III trials in pancreatic and small cell lung cancer. The final analysis was performed in August 2000 after the requisite number of events for the first planned interim analysis had occurred; 54% of patients had progressed and 18% had died.

PATIENT CHARACTERISTICS

performance status was ECOG 0/1/2 in 65/33/2%; median age 57 years; 79% of patients were FIGO stage III; 41% were optimally debulked; 76% had serous histology, and 67% had > or = grade 3 histology. Toxicity was generally grade 1 or 2 in severity, with the most common (BAY 12-9566 vs. placebo) being nausea (26% vs. 13%), fatigue (24% vs. 12%), diarrhea (14% vs. 10%), rash (12% vs. 7%), grade 3/4 thrombocytopenia (3% vs. 1%), and grade 3/4 anemia (5% vs. 1%). Median time to progression (TTP) was 10.4 months (8.5-11.5) for BAY 12-9566 and 9.2 months (7.2-13.9) for placebo (P = 0.67). Median overall survival (OS) was 13.9 months (12.9-infinity) for BAY 12-9566 and 11.9 months (10.5-16.5) for placebo (P = 0.53).

CONCLUSION

We conclude that BAY 12-9566 was generally well tolerated and at the time of the final analysis, there was no evidence of an impact of BAY 12-9566 on PFS or OS.

Pooled safety analysis of BAY 43-9006 (sorafenib) monotherapy in patients with advanced solid tumours: Is rash associated with treatment outcome?

In this analysis of the safety and efficacy of BAY 43-9006 (sorafenib) -- a novel, oral multi-kinase inhibitor with effects on tumour and its vasculature -- pooled data were obtained from four phase I dose-escalation trials. Time to progression (TTP) was compared in patients with/without grade 2 skin toxicity/diarrhoea. Grade 3 hand-foot skin reactions (HFS; 8%) and diarrhoea (6%) were common. At the recommended 400mg bid dose for phase II/III trials (RDP), 15% of patients experienced grade 2/3 HFS, and 24% experienced grade 2/3 diarrhoea. Sorafenib induced stable disease for 6 months in 12% of patients (6% stabilized for 1 year). Patients receiving sorafenib doses at or close to the RDP, who experienced skin toxicity/diarrhoea, had a significantly increased TTP compared with patients without such toxicity (P < 0.05). Sorafenib was well tolerated at the RDP, and induced sustained disease stabilization, particularly in patients with skin toxicity/diarrhoea.

How often should a port-A-cath be flushed?

While it is important during treatment to flush the port-A-cath (PAC) with heparin regularly, catheter maintenance needs to be evaluated in those patients who, after completion of therapy, retained their ports for extended periods of time. The manufacturer has recommended monthly accession to maintain catheter patency and function. Our objective is to demonstrate that a longer interval between maintenance accessions of PACs still may be medically safe, convenient, and more efficient. We performed a retrospective review of all patients who had undergone PAC insertion from 1988 to 1993 at the Albert Einstein College of Medicine, and from 1997 to 2002 at the New York Hospital Medical Center of Queens. An adequate maintenance time is defined as a period of at least 6 months without chemotherapy or total parenteral nutrition. Data collected included date and location of PAC insertion, date of PAC accessions, PAC complications, and results of attempts at flushing the catheters with no venous blood return. All data were entered into an Excel spreadsheet and analyzed. The difference in interval accessions in patients without any complication to patients with complication was calculated using the Mann-Whitney "U" test. A total of 73 patients were included in the study. Compliance with visits for PAC maintenance varied considerably with the individual median accession times varying between 28 and 262 days with an overall median of 42 days. The individual means ranged from 29.5 to 244 days with an overall mean of 53.6 days. Seven patients in the group had episodes where the provider was unable to draw blood from the port during routine accession. The average intervals between accessions for each of these patients ranged from 38 to 244 days. The average intervals of accession among those patients who had no blood return during PAC accession was 79 days, versus 63 days for those without any difficulty. The difference was not statistically significant (p>0.05). Monthly maintenance of PAC is excessive, inconvenient for the patients, and expensive. Extending the interval of PAC maintenance proves to be medically safe and beneficial to the patients, the physicians and the health care system. Our clinical experience suggests that less frequent accessions of PACs is safe and feasible. We strongly advocate future prospective investigation of alternative PAC maintenance protocols in gynecologic cancer patients.

Phase I study to determine the safety and pharmacokinetics of the novel Raf kinase and VEGFR inhibitor BAY 43-9006, administered for 28 days on/7 days off in patients with advanced, refractory solid tumors

BACKGROUND

BAY 43--9006, an oral multi-kinase inhibitor, targets serine-threonine kinases and receptor tyrosine kinases, and affects the tumor and vasculature in preclinical models. Based on its pharmacologic effect, it may be a useful cancer treatment. This study determined the maximum tolerated dose (MTD) of BAY 43-9006 in 42 patients with advanced, refractory metastatic or recurrent solid tumors. Dose-limiting toxicities (DLTs), safety, pharmacokinetics and tumor response were also evaluated.

PATIENTS AND METHODS

In this open-label, phase I, dose-escalation study, BAY 43--9,006 was administered orally in repeated cycles of 35 days (28 days on/7 days off). Eight doses were investigated: from 50 mg every fourth day to 600 mg twice daily. Treatment continued until unacceptable toxicity, tumor progression or death.

RESULTS

The MTD was 400 mg twice daily. BAY 43-9006 was well tolerated, with mild to moderate toxicities; only six patients discontinued study therapy due to adverse events. DLTs consisted of hand-foot skin reaction in three of seven patients receiving 600 mg twice daily. Stable disease was achieved in 22% of patients; median duration of stable disease was 7.2 months. Consistent with its observed half-life of approximately 27 h, BAY 43-9, 006 accumulated on multiple dosing. Increases in exposure were less than proportional to the increases in dose.

CONCLUSIONS

Results indicate that further clinical investigation of BAY 43--9006 is warranted, and suggest it could be a promising future therapy for patients with cancer.