Purpose: HMN-214 is an oral prodrug of HMN-176, a stilbene derivative that interferes with the subcellular spatial location of polo-like kinase-1, a serine/threonine kinase that regulates critical mitotic events. We conducted a dose escalation study of HMN-214 in patients with advanced cancer to assess the safety profile and pharmacokinetics of HMN-214 and to establish the maximum tolerated dose.

Experimental Design: Thirty-three patients were enrolled onto four dosing cohorts of HMN-214 from 3 to 9.9 mg/m2/d using a continuous 21-day dosing schedule every 28 days, with pharmacokinetic sampling during cycle 1.

Results: A severe myalgia/bone pain syndrome and hyperglycemia were dose-limiting toxicities at 9.9 mg/m2/d. A dose reduction and separate enrollment by pretreatment status (lightly versus heavily pretreated) was undertaken, with one dose-limiting toxicity (grade 3 bone pain) at 8 mg/m2/d. The maximum tolerated dose was defined as 8 mg/m2/d for both treatment cohorts. Dose-proportional increases were observed in AUC but not Cmax. There was no accumulation of HMN-176, the metabolite of HMN-214, with repeated dosing. Seven of 29 patients had stable disease as best tumor response, including 6-month stable disease in a heavily pretreated breast cancer patient. A transient decline in carcinoembryonic antigen in a patient with colorectal cancer was noted.

Conclusions: The maximum tolerated dose and recommended phase II dose of HMN-214 when administered on this schedule was 8 mg/m2/d regardless of pretreatment status. Further development of HMN-214 will focus on patient populations for which high expression of polo-like kinase-1 is seen (i.e., prostate and pancreatic cancer patients).

The polo-like kinases (PLK) are a group of highly conserved serine/threonine kinases that serve as regulatory enzymes for mitotic events. Four members of the PLK family members (PLK-1 to PLK-4) have been noted in human cells (1); these kinases are structurally related to the polo gene product of Drosophila melanogaster, Cdc5p of Saccharomyces cerevisiae, and plo1+ of Schizosaccharomyces pombe. PLK-1 seems to play a predominant role in regulating multiple steps in cellular progression through mitosis, including mitotic entry, spindle formation, promotion of anaphase, and cytokinesis (2, 3).

High levels of PLK-1 protein are found in mitotically active cells (4). Several solid tumors express PLK-1, including malignant astrocytomas and glioblastomas (5), prostate cancer (6), pancreatic cancer (7), papillary thyroid carcinoma (8), and colorectal cancer (9). Furthermore, expression of PLK-1 correlates with histologic grade and clinical stage in ovarian cancer (10), and its high expression is an adverse prognostic factor in squamous cell carcinomas of the head and neck cancer, non–small cell lung cancer, and breast cancer (1113). Transfection of cancer cell lines with small interfering RNA targeting PLK-1 resulted in markedly decreased PLK-1 mRNA and protein accompanied by reduced cellular proliferation and increased apoptosis; in an orthotopic model of bladder cancer, transfection of cells with PLK-1-directed small interfering RNA reduced PLK-1 expression and prevented tumor growth (14, 15).

HMN-176 or (E)-4-{2-[2-(N-[4-methoxybenzene-sulfonyl]amino)phenyl]ethenyl}pyridine 1-oxide (Fig. 1) is a novel stilbazole compound that has shown potent cytotoxic activity against several tumor cell lines with an average IC50 of 118 nmol/L (16). Exposure of mitotic cells to HMN-176 results in cell cycle arrest at M phase, with destruction of the spindle polar bodies followed by DNA fragmentation. In vitro studies suggest that HMN-176 interacts with PLK-1 not by direct inhibition but rather by interference with its normal subcellular spatial distribution at centrosomes and along the cytoskeletal structure.4

4

Unpublished data.

In cytotoxicity studies, there is a lack of cross-resistance to HMN-176 in cell lines resistant to cisplatin and etoposide and only limited cross-resistance to doxorubicin and paclitaxel (16). Furthermore, HMN-176 is a modulator of MDR expression in multidrug resistance models of human cancer (17).

Fig. 1.

Chemical structures of HMN-214, HMN-176, HMN-182, and HMN-6001.

Fig. 1.

Chemical structures of HMN-214, HMN-176, HMN-182, and HMN-6001.

Close modal

HMN-214 (Fig. 1) is an orally bioavailable prodrug of HMN-176, which has shown potent antitumor activity in gastric, breast, lung, pancreas, prostate, and colorectal human tumor xenografts (16). Consecutive day schedules of 21- and 28-day duration resulted in better antitumor activity with less toxicity than shorter, intermittent dosing schedules. In the rat 21-day toxicology study, the most sensitive target tissue was bone marrow, and the dose-limiting effect was neutropenia. Female rats experienced higher toxicity than male rats, with correspondingly higher plasma concentrations noted in female compared with male animals.

PLK-1 seems to be an appealing target for anticancer therapeutics given its important role in regulating mitotic events and the high expression of PLK-1 seen in several important solid tumors. We conducted a dose escalation trial of oral daily dosing of HMN-214 in patients with advanced solid tumors. The objectives of the study were to (a) determine the maximum tolerated dose and the dose-limiting toxicities (DLT) of HMN-214 when administered orally on a 21-day continuous dosing schedule every 28 days, (b) characterize the pharmacokinetics of HMN-214 and HMN-176, and (c) evaluate preliminary antitumor activity for HMN-214.

Patient selection. Eligibility criteria included pathologically confirmed advanced solid malignancy for which no standard treatment existed or that had progressed or recurred following prior therapy, at least 18 years old, life expectancy >12 weeks, Eastern Cooperative Oncology Group (ECOG) performance status ≤2, and adequate hematopoietic (neutrophil count ≥1.5 × 109/L and platelets ≥100 × 109/L), hepatic [serum bilirubin <1.5 mg/dL and aspartate and/or alanine transaminase ≤2 times the upper limit of normal (or ≤5 times the upper limit of normal in patients with liver metastases)], and renal (creatinine ≤1.5 mg/dL or creatinine clearance ≥60 mL/min) functions. The principal exclusion criteria were active peptic ulcer disease, a history of gastrointestinal surgery or gastrointestinal abnormalities that would likely affect the absorption of HMN-214, patients requiring scheduled antacids, patients taking drugs known to interfere with cytochrome P450 3A4, a history of severe hypersensitivity to sulfonamides (e.g., Stevens-Johnson syndrome and urticaria), glucose-6-phosphate dehydrogenase deficiency, a history of seizures or patients receiving antiepileptic prophylaxis, known brain or leptomeningeal disease unless stable for ≥8 weeks, severe concurrent illness, history of cardiac ischemic event within the previous 6 months or unstable cardiac arrhythmias, systemic anticancer chemotherapy (including experimental drugs) within 4 weeks of initiation of study drug (6 weeks for carboplatin, mitomycin C, or nitrosourea), radiation treatment within 4 weeks of initiation of study drug, and either pregnancy or breast-feeding.

Patient recruitment was undertaken at the Arizona Cancer Center (Tucson, AZ). The study was conducted in accordance with the Declaration of Helsinki and guidelines on Good Clinical Practice. The protocol was approved by the University of Arizona Human Subjects Protection Program. Written informed consent was obtained from each patient before enrollment on the study.

Study design and treatment plan. This was an open label, dose escalation trial of oral administration of HMN-214 on days 1 to 21 of a 28-day dosing cycle. HMN-214 was administered at a starting dose of 3 mg/m2/d based on the maximum tolerated dose of 5 mg/kg/d determined in the rat 21-day toxicology study using micronized HMN-214. Each patient was given a HMN-214 consumption diary to be completed daily by the patient. DLT was defined as grade 4 neutropenia lasting ≥5 days, grade 3/4 febrile neutropenia regardless of duration, grade 4 thrombocytopenia, grade 3/4 nonhematologic toxicity (except grade 3/4 diarrhea or vomiting without optimal antidiarrheal or antiemetic therapy, respectively), or a treatment delay >2 weeks due to unresolved toxicity in patients who have at least grade 3 thrombocytopenia, grade 4 neutropenia, or any grade 3 nonhematologic toxicity.

Sequential cohorts of three patients, including at least one female and one male patient, per dose level were treated with escalating doses of HMN-214. The initial dose escalation scheme was designed to allow for doubling of the dose of HMN-214 with each sequential cohort until a grade ≥2 hematologic or nonhematologic toxicity was observed, at which point dose escalation was to proceed according to the modified Fibonacci scheme. If consistent hematologic toxicity was observed in the context of extensive prior therapy, patients were to then be stratified in lightly and heavily pretreated cohorts according to the definition of heavy prior treatment as follows: (a) exposure to greater than six courses of an alkylating agent, (b) exposure to greater than four courses of carboplatin, (c) exposure to two or more cycles of nitrosourea or mitomycin C, (d) ≥25% marrow radiation, (e) extensive bony metastases as judged by the study physician, and (f) high-dose chemotherapy with bone marrow transplant.

Before enrollment of the first patient at each subsequent dose level, all three patients at a given dose level were to have reached day 21 of the first cycle of therapy and at least one of the three patients was to have reached day 28 of the first cycle of therapy without experiencing a DLT. If none of three patients at a dose level experienced a DLT, then the next higher dose level was used to treat the following cohort. If one of three patients experienced a DLT, then three additional patients were treated at that same dose level. If none of the additional patients experienced a DLT, then the dose was escalated to the next dose level.

Maximum tolerated dose was defined as the highest dose at which ≤1 of 6 patients experiences a DLT. Intrapatient dose escalation was not permitted. Screening and pretreatment assessments included a medical history, physical examination, assessment of ECOG performance status, complete blood count with differential and platelet count, routine serum chemistries, prothrombin time, international normalized ratio, activated partial thromboplastin time, special serum chemistries including plasma renin activity, aldosterone, uric acid, osmolality and antidiuretic hormone, routine urinalysis, special urinalysis including urine sodium, potassium, chloride, phosphate, uric acid, creatinine, lysine, arginine, urine osmolality, serum tumor markers (where appropriate), creatine kinase, creatine kinase-MB, and creatine kinase-BB fractions if clinically indicated, CXR, electrocardiogram, and radiographic studies for tumor measurements.

Patient evaluations done on days 8, 15, and 22 of cycle 1 included physical exam, ECOG performance status, electrocardiogram if clinically indicated, complete blood count with differential and platelets, routine and special serum chemistries, creatine kinase, creatine kinase-MB, and creatine kinase-BB fractions if clinically indicated, routine and special urinalysis, toxicity assessment, and review of the HMN-214 consumption diary completed daily by the patient. Beginning with cycle 2, patient evaluations included physical exam, ECOG performance status, electrocardiogram if clinically indicated, complete blood count with differential and platelets, prothrombin time, international normalized ratio, activated partial thromboplastin time, routine serum chemistries, routine urinalysis, tumor markers if appropriate, creatine kinase, creatine kinase-MB, and creatine kinase-BB fractions if clinically indicated, toxicity assessment, and review of the HMN-214 consumption diary completed daily by the patient. Electrocardiograms were done every two cycles and as clinically indicated during cycles 1 and 2.

Tumor measurements were done after every two treatment cycles. Response was determined by comparing scans at baseline with those done at first response. Responding patients had confirmation scans done 4 weeks after the first documentation of response. Patients with measurable or evaluable disease were categorized by response status, either complete response, defined as complete disappearance of all clinically detectable malignant disease for at least 4 weeks and without the appearance of new areas of malignant disease, or partial response, defined as ≥50% decrease in the sum of the products of perpendicular diameters of all measurable lesions lasting for at least 4 weeks with no new lesions or progression of evaluable disease. Stable disease was defined as not qualifying for a definition of complete response, partial response, or progressive disease. Progressive disease was defined as ≥25% increase in the sum of products of measurable lesions over the smallest sum observed, reappearance of any lesion that had disappeared, or appearance of any new lesion/site.

Patients were eligible to continue treatment if they continued to meet eligibility requirements, did not develop progressive disease, or did not experience unacceptable toxicity unresponsive to dose modification.

HMN-214 administration. HMN-214 was micronized and supplied as capsules of 1, 5, 10, 40, and 80 mg. The study drug was stored in opaque bottles, and because HMN-214 is light sensitive, it was stored in a closed container, refrigerated at between 2°C and 8°C, and protected from light. Patients took a single oral daily dose of HMN-214 for 21 consecutive days of a 28-day period, considered one treatment cycle. Patients were instructed to take each daily dose in the morning before any intake of food, attempting to achieve a predose fast of at least 2 hours and a postdose fast of 1 hour. Patients were instructed to avoid the cytochrome P450 3A4 inhibitors grapefruit juice and coffee during the period of drug treatment.

Pharmacokinetic monitoring and assay. Patients enrolled at all dose levels had blood and urine samples collected to determine the pharmacokinetics of HMN-214 and HMN-176. Blood samples were obtained on days 1 and 21 of cycle 1 predose and at 0.5, 1, 1.5, 2, 3, 4, 6, 8, 10, and 24 hours postdose and 48 hours postdose on day 21. Additional plasma samples were obtained before and 3 hours postdose on days 8 and 15 of cycle 1 and days 1 and 21 of cycles 2 and 3. For each blood sample, 5 mL whole blood was collected into heparinized, nonseparator green top tubes and immediately placed in an ice-water bath for cooling to <4°C. The sample was centrifuged at 3,000 rpm for at least 10 minutes at <4°C. Two aliquots of plasma were removed and transferred to two amber polypropylene tubes. HCl (0.5 mL; 0.1 N) was added to each sample. The samples were vortexed, frozen, and stored at −20°C or below until assayed.

Urine collection for pharmacokinetic analysis of HMN-214 and HMN-176 as well as secondary metabolites HMN-182 and HMN-6001 (Fig. 1) was done 0 to 4, 4 to 12, and 12 to 24 hours postdose on days 1 and 21 of cycle 1. Urine was stored in brown acid-washed containers at 4°C. The urine volume was recorded and the sample was mixed well, after which a 10 mL sample aliquot was transferred into an amber polypropylene cryotube for shipment. All samples were stored at −20°C or below until assayed.

Human plasma samples containing HMN-214, HMN-176, phenacetin as the internal standard, and heparin as the anticoagulant were extracted with ethyl acetate. The samples were vortex mixed and centrifuged and the lower portion was frozen in an ultracold freezer. The organic layer containing HMN-214, HMN-176, and the internal standard was transferred to a clean tube and evaporated under nitrogen. The residue was reconstituted in water/acetonitrile/formic acid (60:40:0.1, v/v/v). An aliquot was analyzed by reverse-phase high-performance liquid chromatography using a C-8 column maintained at 40°C. The mobile phase was nebulized using heated nitrogen in a Z-spray source/interface and the ionized compounds were detected using a tandem quadrupole mass spectrometer.

Human urine samples containing HMN-214, HMN-176, HMN-182, HMN-6001, and 2-methoxy-4-nitroaniline as the internal standard were diluted once with water and an aliquot of each sample was diluted again with water/acetonitrile/formic acid (60:40:0.1, v/v/v). An aliquot was analyzed by reverse-phase high-performance liquid chromatography using a C-8 column maintained at 40°C. The mobile phase was nebulized using heated nitrogen in a Z-spray source/interface and the ionized compounds were detected using a tandem quadrupole mass spectrometer.

Patient characteristics

Thirty-three patients with advanced solid tumors were enrolled on the study (Table 1). Patient median age was 63 years (range, 37-79 years); 19 patients were men and 14 patients were women. Twelve (36%) patients had an ECOG performance status of 0, 18 (55%) patients had a performance status of 1, and 3 (9%) patients had a performance status of 2. The most common tumor histologies were colon/rectal, non–small cell lung, and breast carcinoma. The majority of patients had been treated with radiotherapy and chemotherapy. Twenty-four (73%) patients had been treated with three or more prior chemotherapy regimens.

Table 1.

Patient characteristics (n = 33)

Median age (range), y 63 (37-79) 
Male/female 19/14 
ECOG performance status, n  
    0 12 
    1 18 
    2 
Tumor histologies, n  
    Colon/rectal 11/2 
    Non–small cell lung carcinoma 
    Breast carcinoma 
    Esophageal carcinoma 
    Metastatic melanoma 
    Liposarcoma 
    Primary peritoneal carcinoma 
    Hodgkin's disease 
    Carcinoid tumor of unknown primary 
Prior therapies, n (%)  
    Radiotherapy 19 (58) 
    Chemotherapy 33 (100) 
Median age (range), y 63 (37-79) 
Male/female 19/14 
ECOG performance status, n  
    0 12 
    1 18 
    2 
Tumor histologies, n  
    Colon/rectal 11/2 
    Non–small cell lung carcinoma 
    Breast carcinoma 
    Esophageal carcinoma 
    Metastatic melanoma 
    Liposarcoma 
    Primary peritoneal carcinoma 
    Hodgkin's disease 
    Carcinoid tumor of unknown primary 
Prior therapies, n (%)  
    Radiotherapy 19 (58) 
    Chemotherapy 33 (100) 

Dose escalation

A total of 67 cycles of HMN-214 were administered (range, 1-6 cycles). The study population consisted of 33 patients who were entered onto four dose levels; two patients could not be evaluated for cycle 1 toxicity due to early withdrawal for progressive disease.

Patients were initially enrolled regardless of their pretreatment status to three dose levels of HMN-214 (Table 2). There was no DLT at 3 and 6 mg/m2/d dose levels. Three patients were then enrolled in the 9.9 mg/m2/d dose level, with one patient experiencing a DLT (a colon cancer patient with grade 3 bone pain in the pelvic bones, bilateral tibias, and feet requiring admission to the hospital on day 18 for further evaluation by imaging studies and treatment with narcotics). This dose level was then expanded to seven patients, with a second patient in this dose level experiencing DLTs (a colon cancer patients with grade 3 hyperglycemia on day 7 and grade 3 myalgias and noncardiac chest pain severe enough to prompt admission to the cardiac care unit for an evaluation to rule out acute myocardial infarction on day 14). Although there was no neutropenia or febrile neutropenia reported in this dose level, emerging safety data from a concurrently enrolling phase I trial of HMN-214 dosed on a daily × 5 schedule included several events of severe febrile neutropenia, including grade 5 febrile neutropenia in heavily pretreated patients, raising concern that heavily pretreated patients might be at greater risk of HMN-214-related toxicities, especially febrile neutropenia, in the current study. The design of the current study was subsequently revised to stratify patients into lightly and heavily pretreated cohorts, consistent with the same stratification scheme applied to the concurrently running trial of HMN-214 on a daily × 5 schedule.

Table 2.

Cycle 1 DLT by dose level and cohort (unselected, lightly pretreated, and heavily pretreated)

HMN-214 dose level (mg/m2/d)
3689.9
Unselected cohort     
    Total n 5* 3 — 7§ 
    No. patients with cycle 1 DLT — 
    DLT — — — Grade 3 pelvic and long bone pain; grade 3 hyperglycemia, noncardiac chest pain, and myalgia 
Lightly pretreated cohort     
    Total n — — 
    No. patients with cycle 1 DLT — — 
    DLT — — Grade 3 long bone pain — 
Heavily pretreated cohort     
    Total n — 
    No. patients with cycle 1 DLT — 
    DLT — — — — 
HMN-214 dose level (mg/m2/d)
3689.9
Unselected cohort     
    Total n 5* 3 — 7§ 
    No. patients with cycle 1 DLT — 
    DLT — — — Grade 3 pelvic and long bone pain; grade 3 hyperglycemia, noncardiac chest pain, and myalgia 
Lightly pretreated cohort     
    Total n — — 
    No. patients with cycle 1 DLT — — 
    DLT — — Grade 3 long bone pain — 
Heavily pretreated cohort     
    Total n — 
    No. patients with cycle 1 DLT — 
    DLT — — — — 
*

Two patients could not be evaluated for cycle 1 toxicity due to early withdrawal for progressive disease.

One patient was lightly and four patients were heavily pretreated by retrospective analysis.

Three patients were lightly pretreated by retrospective analysis.

§

Six patients were lightly and one patient was heavily pretreated by retrospective analysis.

HMN-214 was dose deescalated to levels 6 mg/m2/d for lightly pretreated patients and 3 mg/m2/d for heavily pretreated patients, and separate dose escalations were subsequently done. As shown in Table 2, three lightly pretreated patients were enrolled onto the 6 mg/m2/d dose level with no DLT noted followed by eight patients enrolled in the 8 mg/m2/d dose level, with one of eight patients experiencing a DLT (grade 3 bone pain on day 12 in a breast cancer patient). Three heavily pretreated patients each were enrolled in the 3, 6, and 8 mg/m2/d dose levels with no DLT noted. In a retrospective analysis of the pretreatment status of the unselected cohort, six of the seven patients at 9.9 mg/m2/d were lightly pretreated patients and the two patients who had DLTs were lightly pretreated patients.

Toxicity

Grade 1 to 3 treatment-emergent adverse events are summarized in Table 3 by lightly and heavily pretreated status (includes all patients in the unselected cohort as well as the lightly and heavily pretreated cohorts). Overall, most toxicities were mild in severity. There were no treatment-emergent grade 4/5 events. For both lightly and heavily pretreated patients, respectively, the predominant toxicities were fatigue (25% and 38%); gastrointestinal, including nausea (30% and 46%), vomiting (10% and 46%), anorexia (25% and 15%), abdominal pain (20% and 23%), constipation (20% and 8%), and diarrhea (15% each); and musculoskeletal, including arthralgia (10% and 15%), myalgia (10% and 15%), and bone/limb pain (20% and 8%). Although the majority of adverse events for all patients were grade 1 to 2 in severity, there were a few grade 3 events that were DLTs falling into the category of a severe myalgia/bone pain syndrome requiring hospitalization for evaluation and treatment with narcotics and anti-inflammatory agents. Of note, the patients who experienced DLTs of bone pain did not have painful bony metastases or disease progression; rather, this adverse event was felt related to study drug and was treated with narcotic analgesics and corticosteroids.

Table 3.

Treatment-emergent grade 1 to 3 adverse events by dose level and pretreatment cohort

Adverse eventLightly pretreated patients
Heavily pretreated patients
Dose level (mg/m2/d)
Overall (n = 20)Dose level (mg/m2/d)
Overall (n = 13)
3 (n = 1)
6 (n = 6)
8 (n = 7)
9.9 (n = 6)
3 (n = 5)
6 (n = 3)
8 (n = 4)
9.9 (n = 1)
No. patients with grade 1/2/3 events
Abdominal pain/tenderness  0/1/0 1/0/0 0/2/0 1/3/0 0/1/0   1/1/0 1/2/0 
Anemia   0/1/0  0/1/0   0/0/1  0/0/1 
Anorexia   1/0/0 4/0/0 5/0/0 1/0/0   1/0/0 2/0/0 
Arthralgia 1/0/0   0/1/0 1/1/0 1/0/0 0/1/0   1/1/0 
Ataxia   0/1/0  0/1/0      
Bone pain   0/0/1 0/0/1 0/0/2      
Chest pain (noncardiac)    0/0/1 0/0/1      
Constipation    0/4/0 0/4/0 1/0/0    1/0/0 
Cough    1/0/0 1/0/0      
Conjunctivitis    1/0/0 1/0/0      
Contusion      1/0/0    1/0/0 
Dehydration   0/1/0  0/1/0      
Dermatitis      1/0/0    1/0/0 
Diarrhea 1/0/0  1/0/0 1/0/0 3/0/0 2/0/0    2/0/0 
Dizziness 1/0/0  0/1/0 1/0/0 2/1/0      
Dry mouth   1/0/0  1/0/0 1/1/0    1/1/0 
Dry skin    1/0/0 1/0/0      
Dyspepsia    1/0/0 1/0/0      
Ecchymosis  1/0/0   1/0/0      
Edema, peripheral 0/1/0   1/0/0 1/1/0    1/0/0 1/0/0 
Erythema  1/0/0  1/0/0 2/0/0    1/0/0 1/0/0 
Esophageal reflux    1/0/0 1/0/0      
Fatigue  0/1/0  2/2/0 2/3/0 0/2/0 0/1/0 0/2/0  0/5/0 
Esophageal reflux    1/0/0 1/0/0      
Headache   1/0/0  1/0/0  0/1/0   0/1/0 
Hepatomegaly    1/0/0 1/0/0    1/0/0 1/0/0 
Hyperglycemia    0/0/1 0/0/1      
Hypoesthesia   2/0/0 1/0/0 3/0/0      
Hypoglycemia    1/0/0 1/0/0      
Insomnia    2/0/0 2/0/0      
Limb Pain         1/0/0 1/0/0 
Joint stiffness           
Limb pain    2/0/0 2/0/0    1/0/0 1/0/0 
Mucositis    0/1/0 0/1/0      
Muscle spasm/cramping   0/1/0  0/1/0   1/0/0  1/0/0 
Muscle weakness    0/1/0 0/1/0      
Myalgia    1/0/1 1/0/1 1/0/0  1/0/0  2/0/0 
Myositis    1/0/0 1/0/0      
Nasopharyngitis    0/1/0 0/1/0      
Nausea  2/0/0 1/0/0 2/1/0 5/1/0 3/0/0 0/1/0 1/0/0 0/1/0 4/2/0 
Paresthesia   1/0/0  1/0/0 1/0/0    1/0/0 
Photosensitivity  0/1/0   0/1/0      
Pruritus   1/0/0 1/0/0 2/0/0      
Pyrexia    1/1/0 1/1/0 1/0/0    1/0/0 
Retching  1/0/0   1/0/0      
Rigors 1/0/0   1/0/0 2/0/0 0/1/0   1/0/0 1/1/0 
Skin discoloration   1/0/0  1/0/0      
Somnolence   0/1/0  0/1/0      
Sweating 1/0/0    1/0/0      
Tachycardia      1/0/0    1/0/0 
Thirst    1/0/0 1/0/0      
Tremor 1/0/0    1/0/0      
Vomiting   1/0/0 1/0/0 2/0/0 3/0/0 0/1/0 1/0/0 0/1/0 4/2/0 
Weakness, generalized    0/1/0 0/1/0      
Adverse eventLightly pretreated patients
Heavily pretreated patients
Dose level (mg/m2/d)
Overall (n = 20)Dose level (mg/m2/d)
Overall (n = 13)
3 (n = 1)
6 (n = 6)
8 (n = 7)
9.9 (n = 6)
3 (n = 5)
6 (n = 3)
8 (n = 4)
9.9 (n = 1)
No. patients with grade 1/2/3 events
Abdominal pain/tenderness  0/1/0 1/0/0 0/2/0 1/3/0 0/1/0   1/1/0 1/2/0 
Anemia   0/1/0  0/1/0   0/0/1  0/0/1 
Anorexia   1/0/0 4/0/0 5/0/0 1/0/0   1/0/0 2/0/0 
Arthralgia 1/0/0   0/1/0 1/1/0 1/0/0 0/1/0   1/1/0 
Ataxia   0/1/0  0/1/0      
Bone pain   0/0/1 0/0/1 0/0/2      
Chest pain (noncardiac)    0/0/1 0/0/1      
Constipation    0/4/0 0/4/0 1/0/0    1/0/0 
Cough    1/0/0 1/0/0      
Conjunctivitis    1/0/0 1/0/0      
Contusion      1/0/0    1/0/0 
Dehydration   0/1/0  0/1/0      
Dermatitis      1/0/0    1/0/0 
Diarrhea 1/0/0  1/0/0 1/0/0 3/0/0 2/0/0    2/0/0 
Dizziness 1/0/0  0/1/0 1/0/0 2/1/0      
Dry mouth   1/0/0  1/0/0 1/1/0    1/1/0 
Dry skin    1/0/0 1/0/0      
Dyspepsia    1/0/0 1/0/0      
Ecchymosis  1/0/0   1/0/0      
Edema, peripheral 0/1/0   1/0/0 1/1/0    1/0/0 1/0/0 
Erythema  1/0/0  1/0/0 2/0/0    1/0/0 1/0/0 
Esophageal reflux    1/0/0 1/0/0      
Fatigue  0/1/0  2/2/0 2/3/0 0/2/0 0/1/0 0/2/0  0/5/0 
Esophageal reflux    1/0/0 1/0/0      
Headache   1/0/0  1/0/0  0/1/0   0/1/0 
Hepatomegaly    1/0/0 1/0/0    1/0/0 1/0/0 
Hyperglycemia    0/0/1 0/0/1      
Hypoesthesia   2/0/0 1/0/0 3/0/0      
Hypoglycemia    1/0/0 1/0/0      
Insomnia    2/0/0 2/0/0      
Limb Pain         1/0/0 1/0/0 
Joint stiffness           
Limb pain    2/0/0 2/0/0    1/0/0 1/0/0 
Mucositis    0/1/0 0/1/0      
Muscle spasm/cramping   0/1/0  0/1/0   1/0/0  1/0/0 
Muscle weakness    0/1/0 0/1/0      
Myalgia    1/0/1 1/0/1 1/0/0  1/0/0  2/0/0 
Myositis    1/0/0 1/0/0      
Nasopharyngitis    0/1/0 0/1/0      
Nausea  2/0/0 1/0/0 2/1/0 5/1/0 3/0/0 0/1/0 1/0/0 0/1/0 4/2/0 
Paresthesia   1/0/0  1/0/0 1/0/0    1/0/0 
Photosensitivity  0/1/0   0/1/0      
Pruritus   1/0/0 1/0/0 2/0/0      
Pyrexia    1/1/0 1/1/0 1/0/0    1/0/0 
Retching  1/0/0   1/0/0      
Rigors 1/0/0   1/0/0 2/0/0 0/1/0   1/0/0 1/1/0 
Skin discoloration   1/0/0  1/0/0      
Somnolence   0/1/0  0/1/0      
Sweating 1/0/0    1/0/0      
Tachycardia      1/0/0    1/0/0 
Thirst    1/0/0 1/0/0      
Tremor 1/0/0    1/0/0      
Vomiting   1/0/0 1/0/0 2/0/0 3/0/0 0/1/0 1/0/0 0/1/0 4/2/0 
Weakness, generalized    0/1/0 0/1/0      

Two hematologic adverse events only were noted, including one grade 2 and one grade 3 anemia in a lightly and heavily pretreated patient, respectively, both at the 8 mg/m2/d dose level. No other drug-related hematologic toxicity was noted. There were trends toward dose dependence in the frequency rates of constipation and fatigue in the lightly pretreated patients; no trends in dose dependence were noted in the heavily pretreated patients. Of the three patients who experienced DLTs, two were male and one was female. Although no formal statistical analysis was done, a review of the entire toxicity profile for the study did not reveal a gender effect.

As the result of overall toxicity analysis, there were no significant differences in the toxicity profiles for the lightly and heavily pretreated patient cohorts, and one of eight patients at 8 mg/m2/d dose level and two of seven patients at 9.9 mg/m2/d dose level experienced DLTs. Thus, the maximum tolerated dose of HMN-214 was defined as 8 mg/m2/d for both lightly and heavily pretreated patient cohorts.

Response

Twenty-nine of 33 study patients were assessable for tumor response. Two patients died before a response assessment could be done, and two patients withdrew from the study before response assessment. No objective responses were noted. Seven of 29 (24%) patients had stable disease. One lightly pretreated patient with breast cancer treated on the 9.9 mg/m2/d dose level had stable disease for 6 months. Although technically classified as lightly pretreated, this breast cancer patient's prior therapy included adjuvant Adriamycin plus cyclophosphamide and 16 cycles of paclitaxel. Additionally, one lightly pretreated patient with colon cancer treated on the 9.9 mg/m2/d dose level had a decline in carcinoembryonic antigen from a baseline level of 208 to 126 at days 21 and 35 followed by an increase to 279 on day 55. Twenty-two of 29 (76%) patients had progressive disease.

HMN-214 and HMN-176 pharmacokinetic analysis

Plasma pharmacokinetics. Plasma concentrations of HMN-214 were below the quantifiable limit of the assay (<0.1 ng/mL) for the majority of the patient samples; thus, no pharmacokinetic analysis of HMN-214 was done.

HMN-176 mean pharmacokinetic values of days 1 and 21 are summarized in Table 4. Figure 2 shows the plasma concentration profile of HMN-176 on days 1 and 21. Plasma concentrations were detectable within 30 minutes of dosing for most patients. Tmax were between 2 and 3 hours postdose on day 1, with modest increases seen on day 21. Corresponding mean AUC0-24 on day 21 were comparable with the mean AUC0-∞ on day 1. The AUC ratios between day 21 AUC0-24 and day 1 AUC0-∞ were similar among the dose groups and ranged from 0.85 to 1.33. On day 1, the mean terminal t1/2 were dose independent and ranged from 10.3 to 12.1 hours. The terminal t1/2 on day 21 were similar to those observed on day 1 and ranged from 10.0 to 11.1 hours. There were no statistically significant gender differences in Cmax, AUC0-24, and AUC0-∞.

Table 4.

Pharmacokinetic values of HMN-176 on days 1 and 21 of HMN-214 dosing

Variable
HMN-214 dose level (mg/m2/d)
3689.9
Day 1     
    n 11 
    Cmax (ng/mL) 107.2 ± 30.6 222.7 ± 111.9 283.1 ± 103.4 309.4 ± 86.7 
    Tmax* (h) 2.28 (1.5-9) 2.00 (1-4) 3.00 (2-10) 2.02 (1.5-20) 
    AUC0-∞ (ng·h/mL) 2,144.1 ± 1,241.0 4,150.1 ± 3,145.3 7,066.6 ± 6,137.7 7,441.6 ± 4,220.7 
    t1/2 (h) 12.1 ± 6.2 10.3 ± 5.2 11.3 ± 6.4 11.3 ± 6.3 
    Urinary excretion (%) 10.1 ± 5.3 7.7 ± 3.3 10.4 ± 2.8 9.2 ± 5.9 
Day 21     
    n 
    Cmax (ng/mL) 138.1 ± 40.8 295.1 ± 116.7 411.1 ± 255.2 463.4 ± 132.7 
    Tmax* (h) 3.53 (1-10) 3.00 (1.5-24) 2.00 (1.5-8) 1.97 (0.5-10) 
    AUC0-24 (ng·h/mL) 1,775.9 ± 1,110.1 3,997.8 ± 2,141.4 5,955.6 ± 4,414.3 5,909.8 ± 2,409.2 
    AUC ratio 0.85 ± 0.35 1.17 ± 0.51 0.93 ± 0.20 1.33 ± 0.63 
    t1/2 (h) 10.5 ± 1.5 10.0 ± 5.2 11.1 ± 4.2 10.1 ± 3.5 
    Urinary excretion (%) 10.3 ± 2.8 8.6 ± 3.4 13.8 ± 3.9 12.6 ± 1.5 
Variable
HMN-214 dose level (mg/m2/d)
3689.9
Day 1     
    n 11 
    Cmax (ng/mL) 107.2 ± 30.6 222.7 ± 111.9 283.1 ± 103.4 309.4 ± 86.7 
    Tmax* (h) 2.28 (1.5-9) 2.00 (1-4) 3.00 (2-10) 2.02 (1.5-20) 
    AUC0-∞ (ng·h/mL) 2,144.1 ± 1,241.0 4,150.1 ± 3,145.3 7,066.6 ± 6,137.7 7,441.6 ± 4,220.7 
    t1/2 (h) 12.1 ± 6.2 10.3 ± 5.2 11.3 ± 6.4 11.3 ± 6.3 
    Urinary excretion (%) 10.1 ± 5.3 7.7 ± 3.3 10.4 ± 2.8 9.2 ± 5.9 
Day 21     
    n 
    Cmax (ng/mL) 138.1 ± 40.8 295.1 ± 116.7 411.1 ± 255.2 463.4 ± 132.7 
    Tmax* (h) 3.53 (1-10) 3.00 (1.5-24) 2.00 (1.5-8) 1.97 (0.5-10) 
    AUC0-24 (ng·h/mL) 1,775.9 ± 1,110.1 3,997.8 ± 2,141.4 5,955.6 ± 4,414.3 5,909.8 ± 2,409.2 
    AUC ratio 0.85 ± 0.35 1.17 ± 0.51 0.93 ± 0.20 1.33 ± 0.63 
    t1/2 (h) 10.5 ± 1.5 10.0 ± 5.2 11.1 ± 4.2 10.1 ± 3.5 
    Urinary excretion (%) 10.3 ± 2.8 8.6 ± 3.4 13.8 ± 3.9 12.6 ± 1.5 

NOTE: Mean ± SD.

*

Median (range).

Total percent of dose excreted as free HMN-214, HMN-176, HMN-182, and HMN-6001.

Fig. 2.

Plasma concentration profile of HMN-176 on days 1 and 21.

Fig. 2.

Plasma concentration profile of HMN-176 on days 1 and 21.

Close modal

The relationships between HMN-214 dose and HMN-176 Cmax and AUC for days 1 and 21 were analyzed, respectively. The 90% confidence interval for the slope of the AUC was 0.33 to 1.18, suggesting that AUC was linearly proportional to dose. In contrast, the 90% confidence interval for Cmax was 0.284 to 0.7955, suggesting that Cmax and dose were not linearly correlated.

Urine pharmacokinetics. No quantifiable levels of HMN-214 were observed in any of the day 1 or 21 urine samples collected during the 24 hours after drug dosing. The combined free form concentrations of HMN-176 as well as secondary metabolites HMN-182 and HMN-6001 excreted in the urine accounted for ∼10% of the HMN-214 dose (mean range, 7.7-13.8%).

This is the first report of clinical trial of the novel oral stilbene derivative HMN-214 in advanced solid tumor patients. HMN-214 is a prodrug of HMN-176, which alters the cellular spatial orientation of PLK-1, a kinase that is an important regulator of mitotic events. PLK-1 is highly expressed in a broad range of solid tumors, and it represents a novel cell cycle therapeutic target.

We defined the maximum tolerated dose and recommended phase II dose for HMN-214 to be 8 mg/m2/d based on two DLTs at 9.9 mg/m2/d and one DLT at 8.0 mg/m2/d that fit under the broad category of musculoskeletal adverse events, which included bone pain (not related to metastatic lesions), arthralgias, and myalgias (including severe noncardiac chest pain). This clinical picture resembles a quite severe form of the arthralgia/myalgia syndrome seen with the taxanes, drugs that also interact with the mitotic apparatus (1821). Due to the severity of these events, so severe that both patients treated at 9.9 mg/m2/d required hospitalization during the third week of dosing for further evaluation as well as narcotic analgesia, we did not feel that this dose level could be tolerated, especially given the continuous daily dosing regimen used in the study.

We originally enrolled patients onto dose levels of HMN-214 regardless of their pretreatment status. Although unselected patients experienced DLTs that were not neutropenia or febrile neutropenia at 9.9 mg/m2/d, febrile neutropenia with several deaths was observed at higher dose in a concurrently running phase I trial of HMN-214 on the daily × 5 schedule. Given that the dosing schedule of the current study was much more prolonged (daily × 21) and in light of the animal toxicology studies suggesting that neutropenia would likely be a DLT, overriding safety concerns prompted stratification of patients on this trial by pretreatment status. In fact, over all cohorts studied regardless of pretreatment status, we did not observe neutropenia on the dosing schedule used here, only very rare grade 2 to 3 anemia. Nor did we see a difference in the overall toxicity profile of HMN-214 by pretreatment status. Thus, in retrospect, stratification into pretreatment cohorts based on results the concurrently running trial using a different dosing schedule may have been premature but was based on safety concerns, especially given the prolonged dosing schedule in the current study. These results illustrate that dosing schedules can significantly affect the toxicity profile of a given drug.

Other nonhematologic toxicities related to HMN-214 were constitutional and gastrointestinal in nature. In contrast with other microtubule-inhibiting compounds, such as the Vinca alkaloids and the taxanes, there was little, only mild sensory neuropathic toxicity noted. However, a relatively high incidence of constipation (18% overall) was noted, likely representing autonomic neuropathic toxicity.

Because animal toxicity data had suggested a gender effect for toxicity, the study design ensured the enrollment of both genders at each dose level. No significant gender effect was noted by an informal review of the toxicity profile of this study, and no significant gender effect was noted in pharmacokinetic variables.

Pharmacokinetic analysis showed HMN-214 to be rapidly hydrolyzed to HMN-176, which was rapidly detected in the plasma after dosing. Dose-proportional increases were observed in AUC but not Cmax. No appreciable differences were observed in terminal t1/2 after single or multiple oral doses, suggesting no appreciable drug accumulation with continuous daily dosing over 21 days.

In this patient population of advanced solid tumor patients who were not selected based on PLK-1 expression in tumor tissue, there was only very modest evidence of antitumor activity, with 24% of patients having had stable disease. This included stable disease of 6-month duration in a patient with heavily pretreated breast cancer. Additionally, there was a transient decline in tumor marker in one patient with colon cancer.

In summary, we have shown the feasibility of administering HMN-214 in advanced solid tumor patients on a prolonged schedule of administration. Further development of HMN-214 will focus on patient populations for which high expression of PLK-1 is seen (i.e., prostate and pancreatic cancer patients; refs. 6, 7, 22). Further optimization of patient populations for future trials with HMN-214 could be made by selection of patients by tumor expression of PLK-1 by immunohistochemical or microarray analysis.

Grant support: NS Pharma, Inc. (Parsippany, NJ), a subsidiary of Nippon Shinyaku Co. Ltd. (Kyoto, Japan).

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.

We thank Steve Marsh (ILEX Oncology Services, Inc., San Antonio, TX) for monitoring support.

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