Purpose: The purpose of this study was to define the safety and pharmacodynamics of GEM231, a mixed backbone antisense oligonucleotide targeting the type I regulatory subunit α of protein kinase A, administered as a continuous i.v. infusion.

Experimental Design: Fourteen cancer patients received escalating doses of GEM231 as a 3-day (1 patient) or a 5-day continuous i.v. infusion (13 patients) at doses ranging from 80 to 180 mg/m2/day.

Results: The maximum tolerated dose of GEM231 was 180 mg/m2/day, based on dose-limiting elevation of serum transaminases (STs). At the recommended Phase II dose, 120 mg/m2/day (n = 8), the median number of cycles delivered was 2 (range, 1–4 cycles). Toxicities were tolerable, with one patient experiencing grade 3 ST elevation after 8 weeks. Plasma activated partial thromboplastin time changes were transient, reached a peak at the end of each weekly infusion, and were not associated with spontaneous bleeding. There was a significant difference between the mean preinfusion and postinfusion activated partial thromboplastin time measurements (2.05 s; P = 0.029). The most significant nonhematological toxicity was elevation in ST, usually observed after ≥4 weeks of therapy. There was a positive correlation between weekly dose and change in aspartate and alanine aminotransferase from baseline [r2 = 0.56 (P = 0.031) and r2 = 0.64 (P = 0.019), respectively]. ST elevations were reversible to near baseline in all patients within 3–4 weeks of interruption of GEM231 dosing. Low-grade fatigue was common (57%), cumulative by weeks 4–6, and reversible after GEM231 discontinuation.

Conclusions: GEM231 administered as a continuous infusion is safe; however, continuous protracted dosing is limited by ST elevations. Alternative dosing schedules should include intermittent administration to minimize cumulative toxicity. Additional studies using intermittent continuous infusion schedules of GEM231 are warranted.

The clinical development of AONs3 as cancer therapy has gained momentum since the first antisense drug formivirsen (Vitravine) was approved by the United States Food and Drug Administration for the treatment of AIDS-associated CMV retinitis (1). Despite the unconventional mode of administration of formivirsen by direct intravitreal injection, the proof of principle of clinical benefit with AON suggests that other well-chosen targets for antisense inhibition may also be feasible (e.g., G 3139 targeting Bcl-2 and ISIS 3521 targeting protein kinase C-α). Compared with cytotoxic chemotherapy, oligonucleotides are relatively devoid of side effects. However, there is a dose- and/or sequence-dependent side effect profile that requires modification for better tolerability. Adverse effects of AON include low-grade fever with myalgia attributed clinically to cytokine (e.g., interleukin 6, tumor necrosis factor α, and so forth) induction, asthenia, medically insignificant prolongation of aPTT due to oligonucleotide binding and stabilization of the ternary coagulation complex, thrombocytopenia, hypotension, and elevations in STs [likely secondary to Kupffer cell activation in the liver (2, 3, 4)]. The first generation of AONs displayed all of these side effects that were either sequence independent or sequence specific [e.g., immune stimulation resulted from CpG motifs (2, 5)]. Second-generation oligonucleotides possess segments of modified deoxynucleotides or ribonucleotides. These modifications have led to better in vivo stability, oral bioavailability, and an improved concentration-dependent side effect profile as compared with the first-generation oligonucleotides (2, 3, 4, 5). GEM231 (HYB0165; Hybridon, Inc., Cambridge, MA) is a second-generation oligonucleotide targeting the PKA RIα (6, 7). This oligonucleotide is a phosphorothioate-linked mixed backbone construct containing 2′-O-methyl ribonucleoside modifications of the terminal four bases on the 3′ and 5′ ends.

The PKA holoenzyme is composed of two distinct subunits: catalytic (C) and regulatory (R). They form a tetrameric holoenzyme R2C2 that dissociates in the presence of cAMP into an R2 (cAMP)4 dimer and two free catalytically active C subunits. The only known function for the R subunit is that of inhibiting the C subunit kinase activity (8). Preclinical cancer models have established PKA-I as a therapeutic target (8, 9). In breast cancers, expression of PKA-I is significantly higher than that seen in normal breast tissue. Patients with tumors that demonstrate high PKA RI:RII ratios have poor prognosis in terms of early disease recurrence and death after primary treatment (10). In patients with breast cancer who have undergone serial biopsies, there is a decrease in PKA RIα mRNA after tamoxifen treatment in responding tumors; however, little change is observed in nonresponding tumors (11). In animal model systems of human breast cancers, exposure to antisense RI oligonucleotides slows cell proliferation and tumor growth (12). Tortora and coworkers (9) have demonstrated that the PKA-type I inhibitors (including AONs) enhance the effects of cytotoxic drugs in vitro and in vivo. Specifically, GEM231, used alone or in combination with other therapies, has demonstrated superior antitumor activity in a variety of in vitro and in vivo human tumor models (10, 11, 12, 13, 14).

Based on the expansive array of preclinical studies as well as clinical observations regarding PKA as a therapeutic cancer cell target, a Phase I study was carried out using a 2-h infusion administered on a twice-weekly schedule. The MTD was 360 mg/m2, and 240 mg/m2 was recommended as a dose acceptable for Phase II development. The DLTs were cumulative ST elevations. The plasma half-life of GEM231 was between 0.8 and 1.6 h; however, the tissue half-life was predicted to be much longer (6, 15). Furthermore, as with most oligonucleotides, high peak plasma concentrations (or Cmax) correlated with larger changes in aPTT from baseline (6). Preclinical studies of oligonucleotides have suggested that prolonged or protracted delivery may result in prolonged target inhibition (16, 17). Based on this concept and to avoid high peak plasma concentrations, we embarked on a Phase I clinical study of GEM231 administered as a continuous i.v. infusion without any scheduled break in drug delivery.

This Phase I study was a single-center, open label, single-arm trial conducted at the Albert Einstein College of Medicine and Montefiore Medical Center from January 2000 to May 2002. The protocol and consent form were approved by the Albert Einstein College of Medicine Committee on Clinical Investigations and the Montefiore Medical Center Institutional Review Board before patient enrollment began. All patients were required to provide a signed informed consent before treatment initiation on study.

Study Drug.

GEM231 (HYB0165) is an 18-base DNA/RNA mixed-backbone phosphorothioate oligonucleotide synthesized by Hybridon, Inc. The sequence (5′-GCGUGCCTCCTCACUGGC-3′) is complementary to the mRNA of the RIα subunit of PKA-I at the NH2-terminal codon 8–13. The underlined four bases on the 5′ and 3′ ends have ribose sugars modified with a 2′-O-methyl group; the 17 internucleotide linkages are chiral O-linked phosphorothioate. The molecular weight of the sodium salt form is 6287 and 5913 as the free acid. The oligonucleotide was supplied in lyophilized form and reconstituted on-site in normal saline to a final concentration of 10 mg/ml. Reconstituted GEM231 in normal saline was stable at ambient temperatures for at least 10 days.

Patient Population.

Adult patients (18 years or older) were eligible if they had histological documentation of clinically measurable or evaluable disease. In addition, it was required that no “standard” or reliably effective treatment was available at the time of enrollment to this study. Patients were required to have an ECOG PS of ≤2 and adequate organ function. The latter was defined as an ANC ≥ 1500/μl; platelet count ≥ 100,000/μl; hemoglobin ≥ 9.0 g/dl; prothrombin time/aPTT within institutional “normal” limit; serum creatinine ≤ 1.25 times upper limit of institutional normal; serum bilirubin ≤ 1.25 times upper limit of institutional normal; and ALT and AST ≤ 3 times the upper limit of institutional normal. Patients must have completed all cancer directed treatments (surgery, chemotherapy, and/or radiation) at least 3 weeks before initiation of study drug. All prior therapy-related toxicities must have resolved to ≤grade 1. Patients with a history of bleeding diathesis or with documented coagulation factor(s) abnormalities were excluded from study entry. Other exclusion criteria included renal tubular dysfunction (≥2+ proteinuria on urine dipstick), known hypersensitivity to any oligonucleotides, or progressive central nervous system metastases requiring medical or surgical intervention.

Treatment Plan.

GEM231 was administered on an outpatient basis as a 3-day (72 h) or 5-day (120 h) continuous infusion through a central venous access device (either a Port-a-Cath or a Peripherally Inserted Central Catheter) using a battery-operated continuous ambulatory infusion CADD pump (SIMS Deltec Inc., St. Paul, MN). The treatment was repeated weekly without a scheduled break until disease progression or manifestation of intolerable toxicities. The drug was given at four dose levels: (a) 80 mg/m2/day over 3 days; (b) 80 mg/m2/day over 5 days; (c) 120 mg/m2/day over 5 days; and (d) 180 mg/m2/day over 5 days. The starting dose of 80 mg/m2/day administered over 3 days every week (240 mg/m2/week) represented 50% of the RPTD from a previously reported trial using a 2-h twice-weekly infusion schedule (6). Subsequent escalations were based on toxicities observed in the prior dose cohorts using the NCI’s accelerated titration scheme without intrapatient dose escalation (design 4A; Ref. 18). Upon development of ≥grade 2 toxicity or above a weekly dose of 400 mg/m2, the increment in dose escalation was reduced to 50%, and cohort size was increased to at least three patients. Accrual to the next higher dose level was begun after the last patient at the previous dose cohort had been observed for at least 4 weeks after the start of treatment. The observation of DLT resulted in expansion of that dose level to six patients. MTD defining DLT (based on the Expanded NCI CTC) was determined only in the first 4 weeks of therapy. This was defined as grade 4 hematological toxicity; ≥grade 3 flu-like symptoms, ≥grade 3 aPTT elevation, and ≥grade 3 transaminase elevation. The MTD was defined as the dose at which at least 33% of six patients experienced DLT, and the RPTD was defined as one dose level below the MTD. Disease measurements were conducted every 8 weeks while on treatment, and patients were observed for toxicities for at least 4 weeks after discontinuation of therapy. GEM231 treatments were continued until disease progression or manifestation of intolerable toxicities.

Safety Assessment.

Throughout the study, patients were required to have history and physical examinations at the beginning of every cycle (4 weeks). Vital signs were monitored with initiation and discontinuation of each infusion period. Laboratory monitoring included a complete blood and differential count, serum electrolytes, liver and renal function tests, urine analysis, and prothrombin time/aPTT measured before the start and at the end of each weekly infusion.

Statistical Analysis.

Descriptive statistics were used to describe patient characteristics on study. DLT relationships (e.g., dose-peak aPTT, dose-percentage change in aPTT, nadir ANC count, and nadir platelet count) were determined using the Spearman correlation. Simple linear regression was applied to determine dose-pharmacodynamic relationships. Linearity was determined by initial inspection of graphically plotted data and confirmed using the Passing and Bablock Conversion Method and Cusum Test for linearity. The pre- and postinfusion data were analyzed using the t test. All analyses were performed using SPSS statistical package version 10.0 (SPSS Inc., Chicago, IL).

Patient Characteristics

Fourteen patients were enrolled (Table 1), and all were eligible for toxicity and response assessment. However, three patients did not have posttreatment computed tomography scans but were removed from the study based on tumor marker progression and/or clinical deterioration. The median age was 60 years, eight (57%) patients were female, >90% had an ECOG PS of 0–1, and >80% had prior chemotherapy. The primary site of disease involvement was colorectal cancer (42.9%) and gynecologic malignancies (including primary peritoneal, 42.9%). The median duration since the last cancer-directed therapeutic intervention was 6 weeks (range, 4.5–26 weeks). All patients had adequate blood tests as described in the eligibility and other screening examinations before study entry.

Toxicity

Fourteen patients at four dose levels received 78 [median, 4.5; range, 3–14] weeks of GEM231 given as a multiday continuous infusion (Table 2). At the first dose level of 80 mg/m2/day (240 mg/m2/week), no cycle 1 DLT was observed. At the next dose level, at 80 mg/m2/day (400 mg/m2/week), three patients were enrolled, and there was no episode of cycle 1 DLT. However, a 74-year-old man with metastatic prostate cancer developed symptoms of dyspnea 1 week after having been taken off study secondary to progressive disease. He had received 4 weeks of study drug. A diagnostic evaluation at this time included an echocardiogram that revealed pulmonary hypertension. The patient did not have a prior echocardiogram, and the baseline pulmonary arterial pressure was not known. This was declared a grade 3 drug-related toxic event. Because dose escalation to the next dose level was under way, and other patients treated at the same dose level did not experience similar side effects, the study was continued without interruption. At dose level 3, 120 mg/m2/day (600 mg/m2/week), no cycle 1 drug-related DLT event was observed among the three patients treated. The dose was escalated to 180 mg/m2/day (900 mg/m2/week), and two patients were enrolled. Both patients had cycle 1 DLTs (grade 4 ST elevation in week 4 and grade 3 ST elevation in week 3) in cycle 1. This dose defined the MTD, and subsequently, five additional patients (total = eight patients) were enrolled at 120 mg/m2/day (600 mg/m2/week) to better understand acute and chronic toxicities. At this dose, which defined the RPTD, GEM231 was well tolerated (Tables 3 and 4). Overall, only one patient treated at the RPTD required dose reductions for toxicity (grade 3 STs elevation after 8 weeks of therapy).

Hematological Toxicity.

Neutropenia and thrombocytopenia were uncommon (Table 3, A and B). In cycle 1 (Table 3A), grade 2 neutropenia was observed only in one patient at 80 mg/m2/day administered for 5 days (400 mg/m2/week). There was no grade 2 or greater thrombocytopenia or grade 3 or greater neutropenia observed in cycle 1 across any dose level. Beyond cycle 1 (Table 3B), the single patient with grade 2 neutropenia had recurrent grade 2 neutropenia resolving with the next treatment dose. There was no grade 2 or greater thrombocytopenia or grade 3–4 neutropenia observed across any dose level. There was no correlation between dose (mg/week) and change in ANC (r2 = 0.005; P = 0.642) or platelet count (r2 = 0.008; P = 0.540) from baseline. Similarly, there was no relationship with dose (mg/week) and percentage of change from baseline of either the neutrophil or platelet count. There was no relationship observed between dose (mg/m2/week) and percentage of change from baseline of the hemoglobin value (r2 = 0.02).

Because dose-related increase in aPTT is well established with other oligonucleotides (2, 3, 7), we examined both time- and dose-related changes in aPTT in this study. There was no relationship observed with dose (mg/m2/week) and absolute aPTT when sampled at the end of each weekly infusion of GEM231 (r2 = 0.024; P = 0.297; Fig. 1,a). Similarly, there was a weak correlation between weekly dose and change in aPTT from baseline to its peak value during each week of GEM231 therapy (r2 = 0.263; P = 0.093; Fig. 1 b). When the mean preinfusion aPTT and postinfusion aPTT were compared, there was a statistically significant increase (μ = 2.05 s; P = 0.029) from baseline. However, this change in aPTT was not found to be clinically significant. There is an apparent pattern for changes from baseline in aPTT and from the start of infusion therapy. The peak effect was seen at the end of infusion for each dose level, but the effect was not consistent for each weekly cycle. There did not seem to be a cumulative effect for changes in aPTT values.

Nonhematological Toxicity.

The most significant nonhematological toxicities were isolated elevations in AST and ALT, without abnormalities in other tests of liver function. Bilirubin was unaffected with oligonucleotide therapy in all but one patient in this study. Changes in AST and ALT were both dose and time related (Fig. 2, a and b). There was a linear increase in the percentage of change from baseline to peak value of AST and ALT as a function of dose [r2 = 0.56 (P = 0.031) and r2 = 0.64 (P = 0.019), respectively; Fig. 2, c and d]. The length of time to reach peak ST levels varied by dose because the two patients treated at the highest dose of 900 mg/m2/week (MTD) developed peak serum AST and ALT levels 14–20 days after the start of the first infusion (approximately 2–3 weeks of continuous infusion of GEM231). However, at dose levels below 600 mg/m2/week, the average time to reach peak serum levels was after 28 or 36 days of continuous therapy (Fig. 2, a and b). The best example of these time-dependent changes were seen in one patient (patient 10), who, after 8 weeks of continuous infusion with GEM231 at a dose of 600 mg/m2/week, developed progressive increases in both AST and ALT, whereas other nonspecific organ-dependent parameters (lactate dehydrogenase and alkaline phosphatase) remained fairly stable (Fig. 3). GEM231 treatment was interrupted after infusion 8, at which time there was grade 1 and grade 3 elevation in AST and ALT, respectively, which constituted a DLT. Interestingly, even after discontinuation of therapy, the patient’s AST and ALT continued to rise to 76 and 329 units/liter, respectively (Fig. 3). Twenty-two days after discontinuation of therapy, AST was near baseline values, whereas ALT was still elevated at 86 units/liter. Treatment was resumed at a dose of 400 mg/m2/week for a total of six infusions (i.e., 6 weeks of continuous therapy), and the ST level remained stable. Treatment was discontinued at this point due to disease progression.

Fatigue with generalized weakness was commonly reported by patients (57%) but was generally low grade (grade 1) but cumulative by week 4–6 of continuous GEM231 infusion. However, in cycle 1, grade 2 fatigue was observed in two patients treated at 400 mg/m2/week and in three patients treated at 600 mg/m2/week. Furthermore, in patients receiving two or more cycles of therapy, recurrent fatigue was observed in the same patients who reported fatigue in cycle 1. Fatigue in these patients decreased in severity to grade 1 within days after discontinuation of GEM231, suggesting a causal association. Other toxicities commonly associated with oligonucleotide therapy such as flu-like symptoms were rare and reported only in 2 of 14 patients. These symptoms were treated effectively with over-the-counter nonsteroidal anti-inflammatory agents without sequelae. Nausea and/or vomiting, although reported as associated with GEM231, were always seen in the context of the addition of oral comedications such as opioids for pain control. One patient developed grade 3 esophagitis during week 3 of cycle 1 while receiving 600 mg/m2/week GEM231. This was documented by upper endoscopy when this patient presented with severe postprandial nausea and vomiting. Although grade 3 esophagitis precluded further dosing, the sequence of events leading to erosive esophagitis was likely due to progression of the intra-abdominal malignancy as documented by computed tomography imaging. Hyperglycemia, although rare, was documented in one nondiabetic patient treated at 900 mg/m2/week. This patient had sudden onset of dry mouth and polyuria after 2 weeks on GEM231 with fasting blood sugars >300 mg/dl. The blood glucose level decreased, but it did not decrease to baseline after the discontinuation of therapy, suggesting a causal link.

The MTD of GEM231 administered as a continuous infusion weekly was 180 mg/m2/day (900 mg/m2/week) on the basis of dose-limiting STs elevation observed in both patients enrolled at this dose level. The next lower dose level, 120 mg/m2/day (600 mg/m2/week), is the RPTD. The median number of cycles delivered was 2 (range, 1–4 cycles). At this dose, the toxicities were tolerable, with only one of eight patients demonstrating dose-limiting ST elevation after 8 weeks of therapy. Elevation in aPTT was transient and not dose-limiting, and spontaneous bleeding was not evidenced at this dose level. Although anemia was observed at this dose level, four of eight patients had prior colonic polyps associated with gastrointestinal bleeding and guaiac-positive stools.

There were no objective responses demonstrated in this study. One patient had stable disease, and the median duration of stable disease was 9 weeks. Eleven patients had measurable (elevated) tumor markers at the start of the study. Three patients had a reduction in tumor marker during treatment, and median duration of tumor marker response was 4 weeks. One patient had a ≤25% decrease in tumor marker (CA 125), and two had a 25–50% decrease from baseline (CEA and CA 125, respectively).

This is the first evaluation of a continuous i.v. infusion regimen of GEM231, a mixed backbone oligonucleotide targeting PKA RIα in patients with cancer. GEM231 was administered as a 3-day or 5-day i.v. infusion with escalation of the 5-day infusion dose to 180 mg/m2/day (or 900 mg/m2/week). Unlike the prior reported regimen of a 2-h twice-weekly i.v. infusion of GEM231 (6), both acute (first cycle) and cumulative (beyond first cycle) DLTs were observed at both the MTD and RPTD. Based on our trial, some important new aspects of GEM231 therapy have been established.

GEM231 can be cytotoxic because first cycle DLTs were established at the MTD; however, unlike classical cytotoxic chemotherapy, the toxicities do not include myelosuppression. First-generation oligonucleotides, such as antisense bcl-2 (Genasense), also cause toxicities, which include but are not limited to ST elevations, thrombocytopenia, hypotension, fever, and asthenia (19). Therefore, classic Phase I designs may still have utility in defining MTDs and schedules for second-generation AONs (20).

GEM231, when administered as a continuous infusion, inhibited the coagulation cascade (i.e., led to an increase in the aPTT) in a transient manner, and the kinetics of increase in aPTT were such that peak effect was observed close to the end of infusion. The mechanism of this prolongation has been well studied with ISIS 2302 and is found to be secondary to the inhibition of the intrinsic tenase complex (21). ISIS 2302 is a molecule with a phosphorothioate backbone, and it was suggested that this activity is a general class effect of this group of compounds (21). Within 1–2 days after the end of infusion, aPTT declines to near baseline. These episodes are not associated with spontaneous bleeding. Overall, the mean percentage increase in aPTT from baseline at any dose level is much less dramatic in patients receiving continuous infusion versus those receiving 2-h intermittent infusion GEM231 therapy (6). Although drug pharmacokinetic parameters were not assessed in this study, for first-generation oligonucleotides, Cmax does correlate with certain oligonucleotide-induced toxicities such as aPTT prolongation and complement activation. For second-generation oligonucleotides (GEM231, for example), there was a correlation of Cmax with percentage increase in aPTT (6). In that trial, at the RPTD, 240 mg/m2/dose (480 mg/m2/week), the mean peak aPTT was 44.5 ± 6.4 s (range, 34–58 s), whereas the mean percentage increase in aPTT was 24%. We hypothesize that at the RPTD, using continuous infusion regimen, the Cmax is likely to be lower than a comparable dose administered as a 2-h regimen. In this trial, at a dose of 400 and 600 mg/m2/week, the mean peak aPTT changes were 11.24 ± 0.32 and 14.4 ± 0.94 s, respectively. The mean change in aPTT from baseline was 8.8 ± 16.1% and 11 ± 13.1%, respectively (Table 5). Because these changes are significantly lower than those observed in the 2-h regimen study, we hypothesize that smaller increases in aPTT should be observed at any dose given as a continuous infusion.

Previous studies with second-generation oligonucleotides suggest that there is little liver toxicity associated with oligonucleotide therapy (19, 22); however, with the 2-h regimen of GEM231, ST elevations were dose-limiting and cumulative but reversible (6). The limited number of such events and sample size precluded analysis correlating Cmax or other pharmocokinetic parameters with transaminase elevation; however, it was suggested that slowing the infusion rate might yield better tolerability and less cumulative elevation in STs (6). In our study, ST elevations were dose-limiting, dose related, and time related, depending on the dose level. At the respective RPTDs, the incidence of dose-limiting ST increases (12.5%) was, however, less than that observed in the 2-h infusion schedule (50%). It is hypothesized that ST elevations may occur because oligonucleotides accumulate in the liver; however, the exact nature of the liver toxicity remains undefined (2, 3, 4, 5, 23).

We did not assess complement activation because this was a very minor side effect with the 2-h infusion (6), and other continuous infusion regimens have shown less complement activation compared with bolus schedules (24, 25). However, the occurrence of thrombocytopenia was lower than that observed with first-generation continuous infusion oligonucleotides (2, 3, 4, 5, 23). The incidence of flu-like symptoms was low and comparable with that observed with the 2-h infusion schedule; however, the incidence of fatigue was higher and more severe with the continuous infusion regimen as compared with the 2-h regimen (6).

We did not observe objective antitumor activity in this trial. AONs in general are cytostatic rather than cytocidal. However, this may also be target dependent. With the exception of the bcl-2 AON, objective tumor responses have not been observed in single-agent studies using these compounds (26, 27). However, objective anticancer activity has been noted in combination with chemotherapy (28).

Given that most of these drugs will be used in combination with chemotherapy, trials have been planned to combine GEM231 with the taxanes and irinotecan. These trials are based on encouraging preclinical data demonstrating synergy between GEM231 and cytotoxic agents such as docetaxel and irinotecan (13, 17). Clinical trials using combination therapy have been completed (29) or are ongoing, and the results are eagerly awaited. It is encouraging to note that at least two antisense compounds (G 3139 and ISIS 3521) are being used in combination with chemotherapy and have advanced to Phase III testing (30, 31). For GEM231, future trials would address development of biomarkers for target effect and novel drug combinations using similar infusion schedules.

The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

1

Supported by a grant from Hybridon, Inc. and Cancer Center Core Grant CA-13330-30.

3

The abbreviations used are: AON, antisense oligonucleotide; CMV, cytomegalovirus; aPTT, activated partial thromboplastin time; MTD, maximum tolerated dose; PKA, protein kinase; PKA RIα, regulatory subunit α of PKA type I; ALT, alanine aminotransferase; AST, aspartate aminotransferase; ST, serum transaminase; RPTD, recommended Phase II dose; ECOG, Eastern Cooperative Oncology Group; ANC, absolute neutrophil count; DLT, dose-limiting toxicity; NCI, National Cancer Institute; CTC, Common Toxicity Criteria Version 2.0; PS, performance status.

Fig. 1.

Changes in aPTT with dose.

Fig. 1.

Changes in aPTT with dose.

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Fig. 2.

Time- and dose-dependent changes in STs.

Fig. 2.

Time- and dose-dependent changes in STs.

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Fig. 3.

GEM231 infusion-dependent changes in liver function studies.

Fig. 3.

GEM231 infusion-dependent changes in liver function studies.

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Table 1

Patient characteristics

Patient characteristicsNo. of patients
Patients enrolled 14 
 Males 6 (43%) 
 Females 8 (57%) 
Age [median (range)] (yrs) 60 (45–86) 
ECOG PS  
 0 3 (21%) 
 1 10 (71%) 
 2 1 (8%) 
Prior therapy  
 Chemotherapy 12 (86%) 
 Surgery 7 (50%) 
 Radiation therapy 2 (14%) 
Primary site  
 Colorectal 6 (43%) 
 Ovarian 5 (36%) 
 Others 3 (21%) 
Patient characteristicsNo. of patients
Patients enrolled 14 
 Males 6 (43%) 
 Females 8 (57%) 
Age [median (range)] (yrs) 60 (45–86) 
ECOG PS  
 0 3 (21%) 
 1 10 (71%) 
 2 1 (8%) 
Prior therapy  
 Chemotherapy 12 (86%) 
 Surgery 7 (50%) 
 Radiation therapy 2 (14%) 
Primary site  
 Colorectal 6 (43%) 
 Ovarian 5 (36%) 
 Others 3 (21%) 
Table 2

Dose escalation scheme and cycle 1 DLT events

Dose levelNo. of patientsNo. of weeksCycle 1 DLT eventsOnset
80 mg/m2/day, 3 days None  
2a 80 mg/m2/day, 5 days 18 Grade 3 pulmonary hypertension Posttreatment 
120 mg/m2/day, 5 days 49 None  
180 mg/m2/day, 5 days Grade 3 transaminase elevation Week 3 
    Grade 4 transaminase elevation Week 4 
Dose levelNo. of patientsNo. of weeksCycle 1 DLT eventsOnset
80 mg/m2/day, 3 days None  
2a 80 mg/m2/day, 5 days 18 Grade 3 pulmonary hypertension Posttreatment 
120 mg/m2/day, 5 days 49 None  
180 mg/m2/day, 5 days Grade 3 transaminase elevation Week 3 
    Grade 4 transaminase elevation Week 4 
a

Patient found to have pulmonary hypertension a week after being taken off study secondary to disease progression. Baseline echocardiogram was not performed. This was declared a possible drug-related toxic event. Subsequent patient had started treatment at dose level 3, and trial was continued without interruption.

Table 3

Hematological toxicity

Dose level CTC graden                  aNo. of patients with toxicity
NeutropeniaAnemiaThrombocytopeniaIncrease in aPTT
123123123123
A. Hematological toxicity in cycle 1 only              
80 mg/m2/day, 3 days            
80 mg/m2/day, 5 days      
120 mg/m2/day, 5 days       
180 mg/m2/day, 5 days          
B. Hematological toxicity across all cycles              
80 mg/m2/day, 3 days            
80 mg/m2/day, 5 days      
120 mg/m2/day, 5 days       
180 mg/m2/day, 5 days          
Dose level CTC graden                  aNo. of patients with toxicity
NeutropeniaAnemiaThrombocytopeniaIncrease in aPTT
123123123123
A. Hematological toxicity in cycle 1 only              
80 mg/m2/day, 3 days            
80 mg/m2/day, 5 days      
120 mg/m2/day, 5 days       
180 mg/m2/day, 5 days          
B. Hematological toxicity across all cycles              
80 mg/m2/day, 3 days            
80 mg/m2/day, 5 days      
120 mg/m2/day, 5 days       
180 mg/m2/day, 5 days          
a

n, number of patients.

Table 4

Nonhematological toxicity

Dose level
n                  a80 mg/m2/day, 3 days 180 mg/m2/day, 5 days 3120 mg/m2/day, 5 days 8180 mg/m2/day, 5 days 2
CTC grade1231231231234
A. Nonhematological toxicity in cycle 1 only              
AP elevation          
Hyperbilirubinemia              
Transaminase elevation         
Nausea            
Vomiting            
Mucositis             
Fatigue           
B. Nonhematological toxicity across all cycles              
AP elevation          
Hyperbilirubinemia             
Transaminase elevation       
Nausea            
Vomiting            
Mucositis             
Fatigue           
Dose level
n                  a80 mg/m2/day, 3 days 180 mg/m2/day, 5 days 3120 mg/m2/day, 5 days 8180 mg/m2/day, 5 days 2
CTC grade1231231231234
A. Nonhematological toxicity in cycle 1 only              
AP elevation          
Hyperbilirubinemia              
Transaminase elevation         
Nausea            
Vomiting            
Mucositis             
Fatigue           
B. Nonhematological toxicity across all cycles              
AP elevation          
Hyperbilirubinemia             
Transaminase elevation       
Nausea            
Vomiting            
Mucositis             
Fatigue           
a

n, number of patients; AP, alkaline phosphatase.

Table 5

Dose-related changes in aPTTa

Dose (mg/m2/week)n                  bMean ± SD dose (mg/kg/week)Mean ± SD % change in aPTT
240 7.25 ± 0 9.5 ± 9.3 
400 11.24 ± 0.32 8.8 ± 16.1 
600 14.4 ± 0.94 11 ± 13.1 
900 20.6 ± 2.54 13.5 ± 11.3 
Dose (mg/m2/week)n                  bMean ± SD dose (mg/kg/week)Mean ± SD % change in aPTT
240 7.25 ± 0 9.5 ± 9.3 
400 11.24 ± 0.32 8.8 ± 16.1 
600 14.4 ± 0.94 11 ± 13.1 
900 20.6 ± 2.54 13.5 ± 11.3 
a

Dose-related changes in the mean ± SD percentage change in aPTT from baseline value to its peak value during each treatment week. Doses are described as cumulative dose in mg/m2 and mg/kg/week.

b

n, number of patients.

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