Abstract

BACKGROUND AND OBJECTIVES: Relapsed, histologically aggressive non-Hodgkin lymphoma (NHL) has a poor prognosis; relapsed patients who do not respond to second line therapy or are unfit for BMT have a worse prognosis. Angiogenesis is increased in aggressive NHL and could be targeted by selective cyclooxygenase-2 inhibition and metronomic chemotherapy. We assessed the toxicity of metronomic chemotherapy and the response and progression-free survival in patients with relapsed/refractory diffuse large B-cell lymphoma (DLBCL).
PATIENTS AND METHODS: We prospectively studied 41 patients with a diagnosis of relapsed and/or refractory DLBCL who may have received any number of preceding therapies (as long as one included an anthracycline) and were not candidates for bone marrow transplantation. They received oral cyclophosphamide (50 mg every day), oral methotrexate (2.5 mg 4 times/week) and high-dose oral celecoxib (400 mg twice daily) until there was disease progression or unacceptable toxicity.
RESULTS: All 41 patients (median age, 56 years) were evaluable for toxicity and response, with a median follow up of 9.1 months (range, 4-35 months). At relapse, 51.2% had a high international prognostic index. The treatment protocol was well tolerated with no major toxicities. The most common toxicities were fatigue (61%), nausea (22%), neutropenia (19.5%), and anemia (22%). In 31.7 % there was a partial response and 48.8% had stable disease. Progression-free survival was 12 months. The median response duration was 10 months.
CONCLUSIONS: We conclude that metronomic chemotherapy can be used for patients with relapsed and or refractory DLBCL with reasonable outcome and acceptable toxicity. Standard approaches such as hematopoietic stem cell transplantation and chemo-immunotherapy combinations should be explored prior to a decision on metronomic chemotherapy.

Diffuse large B-cell lymphoma (DLBCL), the most common subtype of non-Hodgkin lymphoma (NHL), is an aggressive disease with considerable biological and clinical heterogeneity. Standard first-line treatment is combination chemotherapy with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) or an equivalent regimen combined with rituximab (R). This results in a complete remission (CR) rate of 75% to 80% and a 3- to 5-year progression-free survival (PFS) of 50% to 80%. The addition of R to CHOP chemotherapy has been the most significant step in recent years in improving overall survival (OS) and PFS rates. Current treatment with CHOP-R results in an improvement in PFS and OS by 15% to 20% compared to CHOP chemotherapy alone.¹

Despite this major therapeutic advance, a significant proportion of patients will relapse or remain refractory to initial chemoimmunotherapy. The PARMA trial confirmed the place of high-dose chemotherapy and autologous hematopoietic stem cell transplantation (aHSCT) as the optimum salvage treatment. In this trial, chemotherapy-sensitive patients were randomized to further salvage chemotherapy with cytarabine/platinum-based chemotherapy alone, or in combination with aHCT. Event-free survival (EFS) and OS at 5 years in the transplant arm were 46% and 53%, respectively, compared with 12% and 32% in the chemotherapy alone arm.²

Numerous salvage chemotherapy regimens have been used to treat relapsed or refractory DLBCL patients. The majority are based on agents that demonstrate non-cross-resistance to those used in primary therapy. Broadly speaking, they can be divided into regimens based on ifosfamide, cytarabine/platinum, or gemcitabine. Studies on salvage therapy have generally included all patients with aggressive lymphoma and are not restricted to DLBCL subtype.³
Recent data indicate that angiogenesis is important in the pathophysiology and prognosis of aggressive histologic subtypes of NHL. Angiogenesis is a multistep process that leads to the formation of new blood vessels from existing vasculature and is associated with the growth and dissemination of malignant tumors.⁴ Angiogenesis and angiogenic factors are increased in most lymphomas. In addition, angiogenesis has been associated with adverse outcomes or more aggressive clinical behavior in malignant lymphoma. However, the role of angiogenesis might vary in lymphoma subtypes because of the prognostic value of microvessel density and the different expression of angiogenesis-related molecules in the various lymphoma subtypes.⁵

Metronomic chemotherapy refers to the frequent, even daily, administration of chemotherapeutics at doses significantly below the maximum tolerated dose, with no prolonged drug-free breaks.⁶ Much evidence, mostly in vitro, indicates that the 'activated' endothelial cells of newly forming blood-vessel capillaries are highly and selectively sensitive to very low doses of various chemotherapeutic drugs.⁷

The findings of Wun et al⁸ reveal that human Burkitt-type B-cell lymphoma cell lines express elevated levels of cyclooxygenase 2 (COX-2), and this fits with earlier studies indicating that B-lineage cells are capable of expressing COX-2. COX-2 is a prostaglandin synthase enzyme that has been implicated in tumorigenesis. One of the proposed mechanisms by which this may occur is by stimulating angiogenesis through the production of proangiogenic factors including vascular endothelial growth factor (VEGF), basic fibroblast growth factor, platelet-derived growth factor, transforming growth factor-h1, and endothelin-1. COX-2 inhibitors, such as celecoxib, have been shown to reduce the incidence of neoplastic lesions in familial adenomatous polyposis and therefore may have a role in the treatment of established malignancies. Furthermore, COX-2 is overexpressed in some lymphomas and is of potential prognostic importance. These preclinical data provide the rationale for using low-dose chemotherapy together with a selective COX-2 inhibitor in the treatment of aggressive NHL.⁹

Patients and Methods

From March 2006 to June 2009, 41 patients with relapsed or refractory DLBCL were enrolled in this phase II study. The primary objective was to determine the response rate to oral high-dose celecoxib combined with daily oral low-dose cyclophosphamide and low-dose methotrexate continuous administration in this patient population. The secondary objectives were to define the toxicity of the given regimen and PFS. Patients were considered eligible if they had relapsed after any number of preceding therapies (as long as one had included an anthracycline) and had a projected life expectancy of >4 months. Patients who relapsed following autologous HSCT were eligible. Patients were excluded from the study if they were transplant eligible, receiving concurrent chemotherapy or radiotherapy (including corticosteroids) or had received any other antineoplastic therapy within the preceding 2 weeks. Patients with Eastern Cooperative Oncology Group performance status of >3, uncontrolled hypertension, and unstable cardiovascular or significant renal or hepatic disease were also excluded. As celecoxib is a sulphonamide, patients with a proven allergy to sulfa drugs were also excluded. Adequate hematologic (hemoglobin count >85 g/L; absolute neutrophil count >1,000/mm³; platelet count >75,000/mm³), renal, and hepatic functions were mandatory. All eligible patients had at least one bidimensionally measurable target lesion. Our institutional review board approved this study and informed consent was obtained from each patient.

Pretreatment evaluations included a complete history and physical examination, routine laboratory evaluation, and CT of the chest, abdomen, and pelvis as well as bone marrow biopsy. Patients were clinically assessed by physical exam and blood work monthly until progression. CT scans were repeated for response evaluation every 2 months or sooner if clinically indicated. Patients were followed off-study until death.

All patients received oral celecoxib 400 mg twice daily (with food), oral cyclophosphamide 50 mg daily, and oral methotrexate 2.5 mg four times a week. In cases of nausea and vomiting (> grade 3), dyspepsia, or abdominal pain or a 50% increase in serum creatinine or liver enzymes, celecoxib was reduced (200 mg orally twice daily, then 100 mg orally twice daily). The need for further dose reduction or gastrointestinal bleeding resulted in discontinuation within the study. Similarly, cyclophosphamide could be reduced twice (to 25 mg orally daily, then 25 mg orally on alternate days) for grade >3 neutropenia or thrombocytopenia. No dose escalations were permitted. Toxicity was assessed according to Common Terminology Criteria for Adverse Event v3.0 (CTCAE) (December 12, 2003). Response to treatment was assessed according to the criteria of Cheson et al.¹⁰

An objective response consisted of complete clinical response, complete clinical response unconfirmed, or a partial response. Progression of disease was determined by an increase of 50% in the product of perpendicular diameters of the index lesions or the appearance of new lesions. All other patients were considered to have stable disease.

Because antiangiogenic therapy is cytostatic, and in many preclinical models of metronomic chemotherapy, tumors may initially grow before they stabilize and sometimes regress, patients were allowed to remain in the study for up to 4 months if radiologic or clinical tumor progression was asymptomatic and not a threat to vital organ function.

Data were analyzed using the SPSS program for Windows version 11. PFS was estimated using the Kaplan-Meier method. Results were considered significant at the 5% critical level (P< .05).

Results

This prospective study included 41 patients with refractory or relapsed DLBCL who presented at the Menofia University Hospital, Clinical Oncology Department between March 2006 and June 2009, and were followed until the end of December 2009. All patients had measurable disease. The time from last relapse ranged from 1 to 10 months with a median of 1.5 months. For patients who received one line of treatment for relapse, the time from last relapse ranged from 3 to 10 months with a median of 8 months. For patients who received 2 lines of treatment for relapse, the time from last relapse ranged from 1 to 9 months with a median of 3 months. For the three patients who received three lines, the time from the last relapse ranged from 1 to 6 months (Table 1).

There was significant correlation between the number of prior protocols and the time to relapse. Patients who received only one line for relapse had a longer time to relapse (P<.05). There was significant correlation between PFS and age (Kendall's tau test). The number of prior chemotherapy protocols given for relapse did not statistically affect PFS in our study.

Toxicity was evaluated according to the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE) version 3.0 (Table 2). Fatigue was the most common side effect with 14 patients (34.1%) having grade I fatigue, 10 patients (24.4%) having grade II fatigue, and one patient (2.4%) having grade III fatigue. No dose reduction or interruption to treatment was necessary except for the patient with grade III fatigue in which treatment was interrupted for one week and then resumed at the usual dose. Gastrointestinal toxicities were mild, ranging from grade I to grade II with no grade III or IV toxicities observed, except for 2 patients who had grade III oral mucositis. Both patients had undergone prior whole neck irradiation for treatment of cervical lymph nodes. Metronomic chemotherapy had to be stopped for two weeks until the condition improved.

Two patients had grade I edema (mostly nutritional) that responded to a short course of diuretics and nutrition support with no treatment interruption. There was no cardiac toxicity observed during the follow-up period of this study. Two patients had grade I hepatic toxicity in the form of elevated liver enzymes, but no permanent drug reduction was needed for toxicity management.

Four of the 7 patients who had progressed (Table 3) died due to progressive disease while the other 3 were shifted to another line of chemotherapy. Among the patients with a partial response, 5 patients ultimately progressed while on therapy at a median of 9 months, with a range of 6 to 12 months. Eight patients with stable disease developed a progressive course at a median of 8.5 months. Patients who progressed were shifted to another line of treatment or kept on best supportive care depending on their general condition.

 The median actuarial PFS was 20 months (95% confidence interval, 13.9-26.0 months) (Figure 1). There was a significant correlation between PFS and age (P=.04) that was a continuous factor observed. There was no significant correlation between PFS and time from last relapse, number of prior lines of chemotherapy or time from last treatment. Also, there was no significant correlation between IPI score and PFS (P=.07).

Discussion

Targeting angiogenesis has also been investigated in the Southwest Oncology Group S0108 study of the anti-VEGF monoclonal antibody, bevacizumab, in patients with relapsed DLBCL. A clinical non-progression rate of 25% was observed for the 51 patients in this study, with a median time to progression of 5 months (range 4 to 18 months).¹¹ In our study, we have shown that the combination of continuous low-dose cyclophosphamide and methotrexate with high-dose celecoxib resulted in a response rate of 32.5% in a group of pretreated patients with relapsed DLBCL. The combination was well tolerated, with a low incidence of hematologic, gastrointestinal, and renal toxicity. There is only one published study on the use of metronomic chemotherapy in treatment of relapsed NHL by Buckstein et al⁹ in which 32 patients with relapsed or refractory NHL were enrolled to receive high-dose celecoxib 400mg twice daily and low-dose oral cyclophosphamide 50 mg daily. Only 20 patients had relapsed or refractory DLBCL, while the others had anaplastic lymphoma, T-cell lymphoma or transformed follicular lymphoma. Most patients were heavily pretreated, with a median of three prior chemotherapy regimens (range, 1-7). Eleven patients (34%) had relapsed after aHSCT. In our study, in which we added methotrexate 2.5 mg four times/week, all patients had relapsed or refractory DLBCL with no other pathological types. None of our patients had received aHSCT. Only one patient in our study achieved complete remission, which occurred after 14 months of treatment, while 31.7% and 48.8% achieved partial response and stable disease, respectively.

In our study, the median actuarial PFS was 20 months (95% CI, 13.9-26.0 months) compared to the Buckstein study⁹ in which the median actuarial PFS was 4.7 months (95% CI, 2.5-9.2 months). In our study, only three patients had grade I skin rash which developed months after initiation of treatment and responded to anti-allergic treatments; no interruption of the program was needed. Fatigue was a common side effect. No thrombotic events were observed in our study.
 We conclude that metronomic chemotherapy can be used for patients with relapsed and or refractory DLBCL with reasonable outcome and acceptable toxicity. Standard lines such as HST and chemo-immunotherapy combinations should be explored prior to a decision on metronomic chemotherapy. We recommend a longer follow up to evaluate the late toxicities of a metronomic chemotherapy schedule. Although there were no thromboembolic events recorded in this study, it is important to closely monitor the patients for these events as they are exposed to high levels of celecoxib. We suggest a study involving a larger number of patients that correlates clinical response with VEGF blood levels and also to determine COX-2 receptor status before and during treatment to assess treatment benefit.

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