Pioglitazone and rofecoxib combined with angiostatically scheduled trofosfamide in the treatment of far-advanced melanoma and soft tissue sarcoma

Authors


Abstract

BACKGROUND

Combined treatment approaches targeting tumor cells as well as stromal cells may control chemorefractory malignancies. In the current study, the authors sought to test one such combined approach in the treatment of chemorefractory melanoma and soft tissue sarcoma.

METHODS

A Phase II trial was initiated to analyze the activity of a continuously administered molecularly targeted treatment regimen (daily pioglitazone [45 mg administered orally] and rofecoxib [25 mg administered orally]) combined with sequentially added angiostatic chemotherapy for patients with previously treated metastatic melanoma (n = 19) or soft tissue sarcoma (n = 21). Angiostatic chemotherapy consisted of trofosfamide (50 mg) administered orally 3 times daily beginning on the 15th day after the start of molecularly targeted therapy.

RESULTS

Forty patients were evaluable for response and toxicity. Major side effects (World Health Organization Grade 3 or 4) were not observed. Objective responses and disease stabilization lasting longer than 6 months were noted in 11% and 11%, respectively, of all patients with melanoma and in 19% and 14%, respectively, of all patients with soft tissue sarcoma. Complete remission was noted in one patient with melanoma and in three patients with sarcoma. Both normal C-reactive protein (CRP) levels and CRP levels that decreased by > 30% during the 14-day biomodulator pretreatment period were found to be predictive of prolonged progression-free survival.

CONCLUSIONS

To our knowledge, the current study is the first to demonstrate that a novel, completely orally administered combined biomodulator/metronomic chemotherapy regimen may be active and well tolerated in patients with chemorefractory malignancies. Cancer 2004. © 2004 American Cancer Society.

Advanced melanoma and soft tissue sarcoma, the two tumor types investigated in the current Phase II pilot study, are characterized by a short median overall survival duration regardless of the systemic chemotherapy regimens used to treat them. In addition, the benefit associated with multiagent treatment of these malignancies (compared with single-agent treatment) remains controversial.1, 2

Preclinical results have indicated that chemorefractory tumors may subsequently respond to metronomic chemotherapy, that vastly different cytotoxic agents administered continuously and at low doses may have highly selective effects on cycling vascular endothelial cells, and that the additional use of angiostatic agents may even induce complete remission (CR).3 The aim of the current study was to achieve tumor control by directly inhibiting tumor cell proliferation, reducing stromal cell plasticity in response to tumor-associated stimuli, and blocking neoangiogenesis. Our findings suggest that a novel, completely orally administered combined biomodulator/chemotherapy regimen can bring about disease control in one-third of all patients with advanced chemorefractory tumors.

The novel treatment regimen investigated in the current study combines two biomodulatory agents (pioglitazone, a dual agonist of peroxisome proliferator-activated receptor [PPAR]-α and PPAR-γ, and rofecoxib, a selective cyclooxygenase-2 [COX-2] inhibitor) with a metronomically administered chemotherapeutic agent (trofosfamide). Metronomic chemotherapy is characterized by long-term, frequent or continuous administration of cytotoxic agents at low doses and without prolonged breaks. Therefore, the acute toxicity that results is expected to be minimal. The cumulative doses administered in metronomic regimens are not necessarily greater than the maximum tolerated doses associated with pulsatile regimens.4

There is growing evidence that antiinflammatory therapy may possess activity against early neoplastic progression.5, 6 Data on the ability of antiinflammatory agents (e.g., rofecoxib and pioglitazone) to control the progression of advanced-stage disease are scarcer.7, 8 Pioglitazone and rofecoxib have been shown to induce differentiation and apoptosis in tumor cells9 and to reduce stromal cell plasticity by inhibiting activation and inducing differentiation or apoptosis in endothelial cells,10 macrophages and dendritic cells,11–13 adipocytes and fibroblasts,14–16 and lymphocytes.15–21

The results of the current study indicate that mechanisms regulating tumor-associated C-reactive protein (CRP) levels may be substantially involved in tumor progression and may be modulated by the combined activity of rofecoxib and pioglitazone. Overall, the study builds on and confirms previous findings made in patients with vascular sarcoma and demonstrates that objective responses also can be achieved in patients with leiomyosarcoma or melanoma.

The clinical study endpoints examined included safety and progression-free survival (PFS) in patients with a variety of advanced chemorefractory tumors. Using prospectively collected data, we retrospectively analyzed the impact of the number of prestudy chemotherapy regimens received and the number of metastatic disease sites on clinical response and evaluated tumor responses in patients with malignancies that were refractory to previous dose-intense chemotherapy. A pretreatment period during which only the two biomodulators were administered was included so that the ability of these two agents to induce clinical responses and changes in laboratory parameters could be assessed.

MATERIALS AND METHODS

Patient Characteristics

The local ethics committee approved the study protocol, and patients were required to provide written informed consent before enrollment. Patients recruited between July 2001 and August 2003 were considered for the current analysis. The date of last follow-up was September 2003.

Patients with advanced, bidimensionally measurable melanoma or soft tissue sarcoma who were experiencing disease progression (defined as an increase of > 25% [relative to the most recent follow-up assessment] in the sum of the sizes of all measurable lesions at the initiation of the study regimen) and who had a life expectancy > 3 months were eligible for the study. Systemic pretreatment was required for patients with melanoma. Patients who had previously received trofosfamide were ineligible for evaluation in the current study.

Additional eligibility criteria included the following: age > 18 years, adequate baseline organ functioning (as evidenced by creatinine concentration < 115 μmol/L; aspartate aminotransferase, alanine aminotransferase, and γ-glutamyltransferase concentrations < 1.25 times the normal concentration; and bilirubin concentration < 1.5 mg/dL [unless elevated concentration levels were tumor associated]), white blood cell count > 2.0 cells per nL, and platelet count > 100 cells per nL. Finally, patients with significant comorbid conditions (including congestive heart failure, angina pectoris, cardiac arrhythmia requiring medical therapy, acute infection, and inadequately controlled diabetes mellitus) were ineligible for the current analysis.

Treatment

Pretreatment (45 mg oral pioglitazone and 25 mg oral rofecoxib) was administered once daily for 14 days before the start of chemotherapy. The pretreatment period was included so that the potential clinical benefit associated with this biomodulatory therapy regimen alone could be assessed. The combination treatment regimen, which was administered continuously for the remainder of the study, included pioglitazone and rofecoxib (administered once daily at the abovementioned doses) along with 50 mg oral trofosfamide administered 3 times daily. Treatment was continued until disease progression was documented or for a maximum of 6 weeks after confirmation of CR. Patients were considered to be nonparticipants in the current study if, for any reason, their trofosfamide therapy was discontinued before the onset of disease progression.

Trofosfamide doses were reduced to 50 mg administered twice daily in the event that leukocyte counts decreased to < 2.0 cells per nL or platelet counts decreased to < 100 cells per nL. Rofecoxib doses were reduced to 12.5 mg administered once daily for patients who developed WHO Grade > 1 edema and for patients who had elevated creatinine levels (> 115 μmol/L).

Evaluation of Efficacy and Safety

Response and toxicity were evaluated in patients who had a follow-up duration of ≥ 1 month. Objective tumor responses were identified using the World Health Organization criteria. Cases of CR, partial remission (PR), and/or disease stabilization lasting > 6 months were grouped together and reported separately for the purposes of the analysis. In selected patients, tumor histology and immunohistology were assessed on follow-up biopsy. An additional written statement of informed consent was required from the patient before sequential biopsies could be obtained.

Biopsies were obtained before and immediately after the 14-day pretreatment period from 4 patients (2 with angiosarcoma and 2 with melanoma). Serial sections prepared from paraffin-embedded tissue samples were stained with hematoxylin and eosin or with immunohistochemical stains for the proliferation marker Ki-67 and, in angiosarcoma cases, the endothelial marker CD31.

Pretreatment Evaluation and Follow-Up

Aside from the acquisition of a medical history, baseline evaluation included a physical examination, an assessment of Eastern Cooperative Oncology Group (ECOG) performance status, a complete blood cell count, serum chemistry assays (including assessment of electrolyte levels), coagulation tests, tumor marker analyses, a chest X-ray, abdominal ultrasonographic scanning, computed tomographic (CT) scanning of the thorax and abdomen (if required for follow-up), and facultative bone scanning or CT scanning of the brain. Patients subsequently were monitored before the start of chemotherapy (but after the biomodulator pretreatment period) and every 3 weeks thereafter, with this monitoring including an assessment of toxicity, serum chemistry assays (one of which measured CRP levels), and a physical examination. Target lesions were assessed (via abdominal ultrasonography or chest X-ray) before each 3-week chemotherapy cycle. When necessary for the evaluation of response, CT scans were obtained at 6–12-week intervals. Finally, at the onset of disease progression, a systematic assessment of all metastatic sites was performed.

Statistics and Data Analysis

The primary endpoints of the current study were PFS and objective response. Secondary endpoints included CR, PR, and/or disease stabilization (grouped together for the purposes of the analysis); survival; and treatment safety. Analyses of safety and response were restricted to patients who received at least 1 cycle (i.e., 3 weeks) of chemotherapy. The time to a given event was estimated using the Kaplan–Meier method. Duration of response was defined as the length of time between the beginning of the response and the onset of disease progression. Time to progression was defined as the interval between the beginning of treatment with pioglitazone and rofecoxib and the onset of disease progression. If the event in question had not yet been observed at the time of last follow-up, the patient was censored at that final time point for the purposes of the corresponding analysis. Survival duration was calculated from the initiation of treatment (intent-to-treat analysis) until death or until September 22, 2003 (whichever came first). Survival distributions were generated using the Kaplan–Meier method. To determine whether CR, PR, and disease stabilization were associated with improved survival, a landmark analysis of the 40 patients who were evaluable for response was performed using the abovementioned definition of survival duration. As part of our exploratory retrospective analysis of PFS, patients with melanoma and patients with sarcoma were assessed for homogeneity in terms of pretreatment characteristics and other treatment-related parameters.

Two variables—number of metastatic sites and number of previously received alkylator-containing treatment regimens—were examined in our univariate analysis of PFS. In addition, PFS was evaluated separately for the following 3 patient groups: 1) patients with serum CRP levels > 3 times the normal level (i.e., > 10 mg/L) who did not experience a CRP response during pretreatment; 2) patients with serum CRP levels > 3 times the normal level who did experience a CRP response (i.e., a decrease of > 30% in CRP levels) during pretreatment; and 3) patients who had serum CRP levels < 10 mg/L throughout pretreatment. Patients who withdrew from the study due to treatment-related side effects were considered to have experienced treatment failure. The relative risk of progression or death was calculated via univariate Cox regression analysis. In addition, the Fisher exact test and the Student t test were used to identify significant associations between clinical and biologic variables.

RESULTS

Patients

In total, 45 patients with AJCC Stage IV melanoma or metastatic soft tissue sarcoma were enrolled in the current study, and 40 of these 45 were evaluable for response and toxicity. The median duration of observation was 12.2 months. One patient was withdrawn from the analysis due to noncompliance, and 4 were withdrawn because they met one of the criteria for exclusion (ECOG performance status > 2, presence of congestive heart failure [New York Heart Association Grade > 2], unavailability for follow-up, and lack of measurable disease in 1 patient each). The baseline characteristics of the 40 evaluable patients are summarized in Table 1.

Table 1. Baseline Patient Characteristics
CharacteristicMelanomaSoft tissue sarcoma
  • ECOG: Eastern Cooperative Oncology Group.

  • a

    Thirty-nine patients had a therapy-free interval of < 3 months before the current trial.

Mean age (range) in yrs59 (30–77)60 (33–77)
Gender  
 Male1012
 Female 9 9
ECOG performance status  
 0/11418
 2 5 3
Mean no. of metastatic sites (range)1.8 (1–6)1.5 (1–5)
No. of patients with progressive disease1921
Mean no. of previous treatment regimens (range)2.6 (1–6)1.8 (1–5)
No. of patients previously receiving systemic treatment1920
 Mean no. of previous systemic treatment regimens (range)1.6 (1–4)1.5 (0–4)
Mean therapy-free interval preceding trial (range) in mosa1.4 (0.6–2.9)1.6 (0.8–3)

Overall, 19 patients with melanoma and 21 patients with soft tissue sarcoma were treated according to the study protocol. All patients with melanoma had Stage IV malignancies. According to the criteria of the American Joint Committee on Cancer, 13 of these 19 patients had M1c disease, whereas 6 had M1b disease; 7 patients with melanoma had elevated lactate dehydrogenase (LDH) levels. Like patients with melanoma, all patients with soft tissue sarcoma in the current study had Stage IV disease (N1 in 1 case and M1 in 20 cases); all documented soft tissue sarcomas were Grade 3 tumors. Nineteen patients with melanoma (100%) and 16 patients with soft tissue sarcoma (76%) had previously received at least 1 chemotherapy regimen, while 5 patients with soft tissue sarcoma (23%) and 13 patients with melanoma (68%) had previously received more than 1 chemotherapy regimen. The metastatic tumor site distributions for patients with melanoma and patients with soft tissue sarcoma, respectively, were as follows: lung, n = 13 and n = 10; liver, n = 7 and n = 9; bone, n = 1 and n = 2; kidney, n = 0 and n = 1; adrenal gland, n = 1 and n = 0; spleen, n = 2 and n = 0; peritoneum, n = 1 and n = 1; skin, n = 1 and n = 1; and urinary bladder, n = 0 and n = 1. Multiple metastatic sites (range, 2–4 sites) were found in 9 patients with melanoma and in 8 patients with soft tissue sarcoma (42% of the overall patient cohort).

Antitumor Activity

The antitumor activity of the study regimen is summarized according to tumor type in Table 2. Objective responses (CR/PR) were observed in 6 of 45 patients (13%; 2 with melanoma and 4 with sarcoma), and disease stabilization lasting ≥ 6 months was documented in another 5 individuals. Ten of the 11 patients who experienced CR, PR, or prolonged disease stabilization were among the 35 patients who had previously received chemotherapy. Nine of these 10 patients had experienced disease progression throughout the course of all previously administered chemotherapy regimens. Objective responses and/or prolonged disease stabilization were observed in patients with all subtypes of soft tissue sarcoma, including fibrosarcoma (1 of 3 patients), leiomyosarcoma (1 of 7 patients), hemangiopericytoma (1 of 3 patients), angiosarcoma (3 of 6 patients), and liposarcoma (1 of 2 patients). Baseline disease characteristics for the 11 patients who experienced CR, PR, or disease stabilization are summarized in Table 3. Two of the four patients with soft tissue sarcoma who had objective responses had previously received ifosfamide-containing chemotherapy. Furthermore, each of the six patients in total who experienced CR or PR initially had a response (clinical and/or histologic) to biomodulator pretreatment (Table 4).

Table 2. Antitumor Activity by Tumor Type
Tumor typeNo of patients (%)
Objective responseSDCR, PR, and/or SDProgressive disease
  • SD: stable disease; CR: complete remission; PR: partial remission.

  • a

    Includes one patient who experienced complete remission.

  • b

    Thirty-three percent of all patients with soft tissue sarcoma experienced complete remission, partial remission, or disease stabilization lasting longer than 6 months.

  • c

    Includes three patients who experienced complete remission.

Melanoma2 (11)a2 (14)4 (22)14 (78)
Fibrosarcomab01 (33) 2 (66)
Leiomyosarcomab1 (14)0 6 (86)
Liposarcomab01 (50) 1 (50)
Hemangiopericytomab01 (33) 2 (66)
Angiosarcomab3 (50)c0 3 (50)
Table 3. Baseline Disease Characteristics in Patients Achieving Clinical Responses
Patient no.GenderAge (yrs)Tumor typeResponse (duration in mos)No. of metastatic sitesNo. of previous chemotherapy regimens
  1. SD: stable disease; CR: complete remission; PR: partial remission.

1Male58MelanomaSD (7.8)1 (M1c)3
2Male63MelanomaPR (5.3)3 (M1c)3
3Female77MelanomaCR (> 20.1)1 (M1c)2
4Female76MelanomaSD (8.0)1 (M1c)1
5Female33FibrosarcomaSD (7.4)13
6Male62LeiomyosarcomaPR (6.1)12
7Female60LiposarcomaSD (6.4)21
8Female39HemangiopericytomaSD (14.6)55
9Female40AngiosarcomaCR (> 5.5)11
10Male67AngiosarcomaCR (4.1)11
11Male52AngiosarcomaCR (> 20.5)10
Table 4. Clinical and Histologic Responses to Biomodulator Pretreatment
Response patternNo. of patientsTumor type(s)
  1. PFS: progression-free survival.

Resolution of B symptoms3Melanoma
Resolution of paraneoplastic syndrome  
 Decreased pro–insulinlike growth factor levels1Hemangiopericytoma
C-reactive protein levels  
 > 30% decrease (median PFS, 3.2 mos)14Melanoma and sarcoma
 < 30% decrease or increase (median PFS, 1.1 mos)6Melanoma and sarcoma
 Normal throughout (median PFS, 5.2 mos)12Melanoma and sarcoma
Stabilization of rapidly progressing disease4Melanoma and sarcoma
Histologically confirmed signs of response4Melanoma (n = 2) and sarcoma (n = 2)

Objective responses were observed at a number of metastatic sites, including the skin, lung, liver, and adrenal gland; bone lesions, gastric lesions, and cases of peritoneal carcinomatosis were not evaluable for response. Objective responses also were documented in patients for whom trofosfamide and/or rofecoxib dose reductions were required. Pioglitazone dose reduction, however, was not necessary for any of the patients in the current cohort.

The lone clinical CR observed in the subgroup of patients with melanoma was found in an individual who had distant skin metastases, lymph node metastases, and elevated serum LDH levels (M1c disease). The lone PR documented in this subgroup occurred in a patient who had distant skin metastases as well as liver metastases (M1c disease).

With regard to the subgroup of patients who had soft tissue sarcoma, CR was noted in three individuals, all of whom were treated for angiosarcoma. One of these three patients had a retroperitoneal primary tumor accompanied by lymph node and lung metastases, another had lung metastases, and a third had an angiosarcoma of the skin accompanied by lymph node metastases. A fourth patient, who had liposarcoma accompanied by liver and lung metastases, experienced PR.

PFS

The median PFS duration was 2.8 months (95% confidence interval [CI], 1.95–3.65 months) for patients with melanoma and 3.8 months (95% CI, 1.7–5.9 months) for patients with soft tissue sarcoma (Fig. 1). Retrospective analyses indicated that PFS was not significantly different (P = 0.762) for patients who had 0 or 1 metastatic site compared with those who had multiple metastatic sites or for patients who had previously received alkylator-containing chemotherapy compared with those who had not (median PFS: soft tissue sarcoma subgroup, 3.6–4.1 months; melanoma subgroup, 2.6–3.1 months). The melanoma and soft tissue sarcoma subgroups were comparable in terms of the number of previously treated patients, the mean number of previously received chemotherapy regimens per patient, and the mean number of metastatic sites per patient (Table 1).

Figure 1.

Progression-free survival of (A) patients with advanced melanoma and (B) patients with soft tissue sarcoma.

Pretreatment with Pioglitazone and Rofecoxib

CRP levels, because of the unique molecular mechanisms by which they are regulated, provide additional information on the activity of certain therapeutic agents (e.g., pioglitazone and rofecoxib). We compared PFS results for the following three groups: 1) patients who had elevated CRP levels (> 10 mg/L) that increased or did not respond to pretreatment with pioglitazone and rofecoxib (3 patients with sarcoma and 3 patients with melanoma [Group 1]); 2) patients who had initial CRP levels > 10 mg/L and subsequently experienced a response to pretreatment (as defined by a decrease of > 30% in serum CRP levels; 8 patients with sarcoma and 6 patients with melanoma [Group 2]); and 3) patients who had low, stable CRP levels (< 10 mg/L) during pretreatment (5 patients with sarcoma and 7 patients with melanoma [Group 3]). No patient was excluded from the analysis of CRP levels due to infection or due to the receipt of antimicrobial therapy for an infection; for 8 patients, however, follow-up data on CRP levels were not available. The mean CRP levels in Group 1, Group 2, and Group 3 were 52 mg/L (range, 15–177 mg/L), 34 mg/L (range, 13–142 mg/L), and 5.4 mg/L (range, 2.0–8.3 mg/L), respectively. The survival distributions for Group 2 and Group 3 were significantly different from the survival distribution for Group 1 (P = 0.004–0.006) (Fig. 2).

Figure 2.

Progression-free survival according to changes in C-reactive protein (CRP) levels during pretreatment with pioglitazone and rofecoxib. Black line: patients with CRP levels < 10 mg/L throughout the pretreatment period; gray line: patients who initially had elevated CRP levels (> 10 mg/L) but experienced a response to pretreatment (i.e., a decrease of > 30% in CRP levels); dotted line: patients who initially had elevated CRP levels and did not experience a response to pretreatment.

Aside from CRP responses, we also observed the resolution of B symptoms, the resolution of a paraneoplastic syndrome, stabilization of rapidly progressing disease, and signs of histologic response in select patients (Table 4). In biopsy samples obtained from two patients with angiosarcoma after the 14-day pretreatment phase, the following signs of histologic regression were observed: 1) the loss of luminal architecture and 2) the presence of mononuclear cell infiltrates. (Nonetheless, positive staining for the endothelial marker CD31 in those same two samples indicated that a high level of vascular structure remained.) Biopsy samples obtained from two patients with melanoma following pretreatment also were suggestive of disease regression, as these samples contained multiple segmental areas in which the invasive component was replaced by mononuclear cell infiltrates and fibrosis. For all four patients whose biopsy findings were indicative of regression, the number of Ki-67-positive tumor cells observed on biopsy was significantly reduced (i.e., by > 50%).

Responses at Various Metastatic Sites

Reductions of > 50% in size could be confirmed in lesions of the skin, lung, liver, urinary bladder, and lymph nodes, with the most rapid responses being observed in skin lesions. During the observation period, 8 of the 11 patients who experienced CR, PR, or prolonged disease stabilization exhibited signs of tumor progression (at the original metastatic site in 6 cases and at a different organ site in 2 cases).

Response Characteristics

Objective responses generally are expected to occur after two or three cycles of dose-intensive chemotherapy.22 Relative to this expectation, the objective responses documented in the current study were delayed, occurring after a mean of 4.3 months (range, 2–7 months) of therapy. The objective response durations were 5.3 and 20.1 months, respectively, for the 2 patients with melanoma who experienced responses and 4.1, 6.1, 5.5+, and 20.5+ months, respectively, for the 4 patients with sarcoma who experienced responses. For some of these patients, responses have persisted even after > 1 year of treatment. Three months after discontinuation of the study regimen, one patient whose disease was in CR experienced a recurrence, which also exhibited sensitivity (objective response) when the study treatment was readministered.

Survival

To date, of the 45 patients enrolled in the current study (intent-to-treat analysis), 40 have died of disease, whereas 5 remain alive. The median overall survival duration was 4.1 months (95% CI, 3.3–5.1 months) for patients with melanoma and 5.6 months (95% CI, 4.4–6.2 months) for patients with sarcoma. Among patients who experienced objective responses or prolonged disease stabilization, the median survival duration was 11.1 months (range, 6.7–27.5+ months) for those with sarcoma and 8.7 months (range, 7.8–20.1+ months) for those with melanoma; for all other patients with sarcoma, the median survival duration was 3.2 months (range, 2.1–6.3 months), and for all other patients with melanoma, the median survival duration was 2.5 months (range, 1.9–6.9 months).

Tolerability and Safety

Treatment generally was well tolerated in both patient subgroups (Table 5). Overall, the most common adverse events were Grade 1–3 edema (20%) and Grade 1–2 hematologic toxicity (25%). Fatigue developing after the initiation of treatment with rofecoxib and pioglitazone also was observed, albeit less frequently; all patients who experienced this side effect received both biomodulators during the evening. Finally, two Grade 2 infections were documented during treatment with trofosfamide. In contrast, nausea, diarrhea, constipation, and gastrointestinal bleeding were not observed in the current cohort.

Table 5. Common Treatment-Related Adverse Events and Dose Modifications
Adverse eventNo. of patients (%)Dose modification
  • a

    Leukocyte counts and platelet counts never less than 1.0 per nL and 100 per nL, respectively.

Edema 8/40 (20)Rofecoxib 12.5 mg
Elevated creatinine levels (> 115 μmol/L) 6/40 (15)Rofecoxib 12.5 mg
Hematologic toxicitya10/40 (25)Trofosfamide 50 mg twice daily

Table 5 summarizes the incidence of dose reduction in the current study. In no case was treatment discontinued due to side effects. In addition, pioglitazone dose reduction was not required for any patient. Blood glucose concentrations did not decrease during pioglitazone administration, and modification of oral treatment was not necessary even for patients with type II diabetes mellitus. Neither treatment-related increases in liver enzyme levels nor persistent increases in plasma creatinine levels were observed.

DISCUSSION

The current study was designed to explore whether a metronomic angiostatic chemotherapy regimen administered in conjunction with two biomodulatory agents possessed efficacy against a range of chemorefractory tumors. The current investigation of patients with soft tissue sarcoma and patients with melanoma serves as a follow-up trial intended to validate and build on previously published findings made in patients with vascular sarcoma.7 Responses previously were documented in patients with angiosarcoma who received a regimen identical to the one used in the current study. Three patients in the previous study with angiosarcoma experienced responses to treatment, and these three patients had survival durations of 18, 21, and 33+ months, respectively.

The current study demonstrates that complete remission can be achieved in patients with refractory melanoma or soft tissue sarcoma, that second-to-fifth-line treatment according to the study protocol can result in PFS rates similar to those associated with first-line treatment of advanced melanoma, and that patients with previously treated metastatic soft tissue sarcoma can experience disease stabilization for extended periods of time. In addition, for some patients, chronification of malignant disease via long-term drug-induced tumor control appears to be a realistic aim, as is indicated by the achievement of tumor control lasting longer than 1 year in 3 patients in the current study. Furthermore, the current report confirms that the study regimen possesses activity in patients with vascular sarcoma.7 To our knowledge, no previous study of continuous low-dose trofosfamide chemotherapy for patients with advanced soft tissue sarcoma or Stage IV melanoma has yielded long-term objective responses such as the ones documented in the current study.23–25 This provides further evidence of the biologic activity of pioglitazone and rofecoxib (beyond the clinical activity of single-agent trofosfamide) in patients with a range of chemorefractory tumors. The sarcoma subgroup in the current study had a median PFS duration that was identical to the one previously reported for patients receiving pulsed trofosfamide followed by continuous maintenance therapy.23, 24

Standard second-line treatment strategies for advanced melanoma and soft tissue sarcoma have not yet been established. Depending on disease subtype, the 6-month PFS rate following first-line therapy ranges from 30% to 57% for patients with soft tissue sarcoma and from 6% to 12% for patients with advanced melanoma.1, 2, 26 In the current study, a considerable response to palliative care was noted among patients with Stage IV melanoma (second-to-fifth-line treatment in 100% of patients; 6-month PFS rate, 21%) as well as among patients with advanced soft tissue sarcoma (second-to-fifth-line treatment in 77% of patients; 6-month PFS rate, 38%).

It is noteworthy that in the current retrospective analysis, neither the number of regimens previously received nor the number of metastatic sites was significantly associated with PFS. These observations are in agreement with the findings of other larger trials,27, 28 which have demonstrated that the clinicopathologic variables that are associated with longer PFS and overall survival often differ from those that are predictive of objective responses to chemotherapy.

Aside from confirming the recently documented antitumor activity of rofecoxib and pioglitazone,7 the current study also demonstrates the ability of these agents to improve ECOG performance status, ameliorate the condition of patients with paraneoplastic syndromes,29 and attenuate tumor-associated CRP levels (Table 4). Dual PPAR-α/PPAR-γ agonists such as pioglitazone may significantly reduce plasma CRP levels by inhibiting interleukin (IL)-1-induced CRP expression.30 IL-1 is a cytokine that is heavily involved in carcinogenesis and tumorigenesis.31, 32 Elevated CRP levels are commonly related to weight loss, cachexia syndrome, extent of disease, and recurrence in patients with advanced malignancies,33–35 and in the current study, patients with elevated tumor-associated CRP levels who did not experience a response to treatment with rofecoxib and pioglitazone had poor prognoses (Fig. 2). In contrast, decreases in CRP levels during pretreatment with these two biomodulators were associated with improvements in PFS. Our ability to use CRP levels to construct patient subgroups with significantly different PFS rates; as well as the prevalence of CRP responses among patients with elevated CRP levels (70%), regardless of tumor type; indicates that the mechanisms regulating CRP levels may be substantially involved in tumor progression. Correspondingly, in addition to suppressing tumor initiation36, 37 antiinflammatory therapy may also play an important role in controlling advanced tumors.

The current trial did not establish whether angiostatic effects, antistromal effects, or direct antiproliferative effects on tumor cells were most responsible for the observed responses. Nonetheless, the current study provides further evidence of the antitumor activity of combined treatment with a COX-2 inhibitor and a PPAR-γ agonist. In addition, it demonstrates that the ability of such a regimen to modulate tumor-associated CRP levels may be closely related to PFS. The considerable antitumor activity associated with combined administration of a COX-2 inhibitor and a PPAR-γ agonist recently was confirmed in an animal model; in that model, combined treatment yielded antitumor effects that were at least additive.38

Combination therapy involving biomodulation (with pioglitazone and rofecoxib) and angiostatically scheduled trofosfamide chemotherapy is feasible and only mildly toxic in patients with heavily pretreated advanced tumors. No unexpected toxicities (i.e., toxicities other than those typically associated with the individual agents used) were observed in the current study. Furthermore, the potentially additive nephrotoxicities of pioglitazone and rofecoxib were managed by reducing rofecoxib doses and, when necessary, adding diuretic agents to the treatment regimen. The toxicity profile of the cytotoxic agent used in the current study was comparable to what has been described previously.23, 24

Thus, the current study has established the feasibility of long-term, low-dose metronomic chemotherapy administered in conjunction with a COX-2 inhibitor and a PPAR-γ agonist. Given that treatment with a COX-2 inhibitor and a PPAR-γ agonist may increase the susceptibility of malignant cells to pulsatile chemotherapy by upregulating proapoptotic cellular mechanisms,38 it appears logical to combine such approaches with the aim of achieving enhanced antitumor effects.

In summary, the treatment schedule presented in the current report has three major advantages: 1) a considerable level of activity against chemorefractory tumors; 2) a mild toxicity profile; and 3) complete oral availability. On the basis of our promising findings regarding toxicity and response, and with the goal of further evaluating the long-term impact of administering rofecoxib and pioglitazone in conjunction with continuous low-dose chemotherapy, we have initiated randomized Phase II trials of the study regimen in patients with metastatic soft tissue sarcoma or Stage IV melanoma.

Ancillary