A pilot study of epratuzumab and rituximab in combination with cyclophosphamide, doxorubicin, vincristine, and prednisone chemotherapy in patients with previously untreated, diffuse large B-cell lymphoma†
Presented in part at the Annual Meeting of the American Society of Hematology, San Diego, California, December 6–9, 2003, and the Annual Meeting of the American Society of Clinical Oncology, New Orleans, Louisiana, June 4–7, 2004.
In this pilot study, the authors assessed the feasibility of combination epratuzumab and rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (ER-CHOP) in patients with newly diagnosed diffuse large B-cell lymphoma (DLBCL).
Patients received chemotherapy on the following schedule: epratuzumab 360 mg/m2, rituximab 375 mg/m2, and standard-dose CHOP every 3 weeks for 6 to 8 cycles. The primary endpoint was the incidence of grade 4 neutropenia and grade 3 or 4 antibody infusional toxicity. Secondary endpoints were the complete response (CR) rate, the overall response rate (ORR), and progression-free survival (PFS). Weekly blood counts were obtained to monitor hematologic toxicity. Fifteen patients were enrolled and treated. Baseline patient characteristics included a median age of 63 years (range, 42–78 years), 60% of patients had stage III or IV disease, 7 patients had a low-risk International Prognostic Index (IPI) score (0 or 1), 7 patients had an intermediate-risk IPI score (2 or 3), and 1 patient was high risk.
Grade 3 or 4 neutropenia was observed in 14 patients (93%) or in 28 of 92 treatment cycles (30%). Three patients developed grade ≥3 infection or fever. Eleven patients (73%) required dose reductions. No grade 3 antibody infusion-related toxicity was reported. Thirteen of 15 patients responded (ORR, 87%,), including 10 CRs (67%), 3 partial responses (20%), 1 patient with stable disease, and 1 patient with disease progression. At a median follow-up of 30 months, 13 of 15 patients remained alive. The 1-year PFS and OS rates were 93% and 100%, respectively; and the 2-year PFS and OS rates were 86% and 86%, respectively.
Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma (NHL) in North America. With combined cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) chemotherapy, remission rates from 45% to 55% can be obtained, and approximately 30% to 35% of patients are cured of their disease.1 Despite further studies with more intensive chemotherapy combinations, response rates, event-free survival (EFS), and overall survival (OS) have not changed.2–9 In Phase II studies, rituximab has demonstrated efficacy in DLBCL either as a single agent or in combination with CHOP chemotherapy (R-CHOP).10–12 The Adult Lymphoma Study Group (Groupe d'Etude des Lymphomes de l'Adulte [GELA]) Phase III study demonstrated that R-CHOP significantly increased the rate of complete response (CR), decreased the rate of treatment failure and recurrence, and improved EFS and OS compared with CHOP alone in elderly patients with DLBCL.13, 14 The Intergroup Eastern Cooperative Oncology Group (ECOG)/Cancer and Leukemia Group B trial also showed that patients who received rituximab either concurrently with CHOP chemotherapy or as maintenance after CHOP had an improved time to treatment failure compared with patients who did not receive any rituximab.15, 16 A similar study in younger patients confirmed those results.17, 18 Based on those and other Phase II studies, R-CHOP has become the standard therapy for patients with newly diagnosed DLBCL in all age groups.10, 13–19
Epratuzumab is a humanized monoclonal immunoglobulin G1 antibody directed against the B cell-specific antigen CD22, a 135-kilodalton membrane sialoglycoprotein that is expressed by pre-B cells and mature, normal B cells. Cell-surface expression is lost during terminal differentiation into plasma cells and after B-cell activation.20 CD22 appears to be involved both in the regulation of B-cell activation through B-cell membrane receptor signaling and in cell adhesion. Because CD22 is lineage restricted, it represents an attractive target for anti-NHL immunotherapy. It is present in approximately 85% of DLBCL.21 It has been observed that epratuzumab is internalized rapidly into antigen-positive cells, and it reportedly induces CD22 phosphorylation, indicating a role in signal transduction.20 Moderate antibody-dependent cell cytotoxicity also has been implicated in its mechanism of action.22, 23 B-cell depletion is moderate (30–50%), and is less than the B-cell depletion by rituximab. Phase I/II studies of single-agent epratuzumab in indolent and aggressive lymphoma showed encouraging safety and efficacy data24, 25: In patients with recurrent or refractory, aggressive NHL, the overall response rate (ORR) was 10%; and, in patients with DLBCL, the ORR was 15%.25 In another Phase II study that used combined epratuzumab and rituximab, the combination was tolerated well and had significant clinical activity (ORR, 67%) in both indolent and aggressive NHL.26 In addition, a European study confirmed those results; patients with DLBCL had a response rate of 47%.27, 28
By targeting different antigens with potentially different, nonoverlapping mechanisms of antitumor activity, and given the single-agent activity of epratuzumab in DLBCL, we hypothesized that the combination of epratuzumab, rituximab, and CHOP (ER-CHOP) may result in enhanced activity over that expected with R-CHOP alone. In this report on the pilot study, we present the final results from patients with newly diagnosed DLBCL who received treatment with a combination of 2 anti-B–cell antibodies, epratuzumab and rituximab, in combination with CHOP chemotherapy.
MATERIALS AND METHODS
This was a pilot study performed at the Mayo Clinic Rochester and the University of Wisconsin-Madison to assess the feasibility of combination ER-CHOP in patients with newly diagnosed DLBCL. The objectives were to evaluate the safety and efficacy, as measured by the complete response (CR) rate, the ORR (partial responses [PRs] and CRs), and the progression-free survival (PFS) rate. Patients received epratuzumab, followed within 1 hour by rituximab, followed by CHOP chemotherapy (for dosing information, see Table 1). Patients received 2 cycles beyond their best response to a minimum of 6 cycles (maximum, 8 cycles) administered every 3 weeks based on complete blood counts. Response assessment occurred after Cycles 4 and 6 and after Cycle 8 for patients who received 8 cycles. Patients were followed every 3 months for 6 months for toxicity and until disease progression or death.
Table 1. Treatment Schedule
ReRx indicates retreatment; IV, intravenous; max, maximum.
Rituximab was rounded to the nearest 50-mg vial.
For the first cycle, rituximab may have been divided and given over Days 1 and 2. If so, then the second half of the rituximab was given on Day 2 followed by combined cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) on Day 2. Epratuzumab always was given on Day 1 before rituximab. For all subsequent cycles, combined epratuzumab, rituximab, and CHOP was given on Day 1.
Patients were eligible for enrollment if they were aged ≥18 years and had a diagnosis of previously untreated, CD20-positive DLBCL according to the World Health Organization classification.29 Patients were required to have measurable disease and to have adequate neutrophils, platelets, liver function, and renal function. Patients were excluded if they had a prior diagnosis of NHL, an ECOG performance score of 3 or 4, active infection that required antibiotics, poor cardiac function, central nervous system lymphoma, positive human immunodeficiency virus status, or another primary malignancy. Staging and pretreatment assessment included clinical examination; computed tomography (CT) scans of the chest, abdomen, and pelvis; blood counts; measurements of lactate dehydrogenase (LDH), liver function, and renal function; bilateral bone marrow aspirate and biopsy; and assessment of left ventricular function by either echocardiography or gated nuclear medicine scan. Lumbar puncture was performed in patients with bone marrow involvement or sinus involvement; patients who had positive cytology for lymphoma were excluded. A pregnancy test was done in women of child-bearing potential. The International Prognostic Index (IPI) was calculated based on age, serum LDH, performance status, extranodal disease, and stage.30
This study was conducted in accordance with the ethical guidelines mandated by the Declaration of Helsinki. All patients signed informed consent that was approved by the institutional review board at each participating site.
Epratuzumab was produced and subjected to quality control at Immunomedics Inc. (Morris Plains, NJ) and was administered at a dose of 360 mg/m2 intravenously over approximately 1 hour. Rituximab (commercially available) was administered at a dose of 375 mg/m2 (rounded to the nearest 50-mg vial) approximately 1 hour after the infusion of epratuzumab. CHOP chemotherapy followed the administration of rituximab. For the first cycle, rituximab was divided into 2 days; the first half of rituximab was given on Day 1, and the second half of rituximab was given on Day 2 followed by CHOP chemotherapy. For subsequent cycles, all therapy was administered on Day 1. Premedication with acetaminophen and diphenhydramine was given prior to epratuzumab and was repeated if necessary. Infusion-related side effects were treated at the discretion of the treating physician, including the use of corticosteroids.
Weekly complete blood count/differential was ob-tained to monitor for hematologic toxicity. Dose modifications were based on adverse events. Hematologic toxicity (absolute neutrophil count ≤0.5 × 109/L) in interim counts resulted in the addition of granulocyte colony-stimulating factor (G-CSF) (Neupogen or Neulasta) to subsequent cycles to maintain dose intensity. If grade 4 neutropenia persisted during subsequent cycles, then cyclophosphamide and doxorubicin were reduced by 25%, and G-CSF was maintained. If hematologic toxicity was still present at Day 1 of the next cycle (absolute neutrophil count ≤1.5 × 109/L or platelets ≤100 × 109/L), then treatment was delayed by 1 week, repeat counts were obtained, and G-CSF was added to subsequent cycles. If hematologic toxicity did not resolve after 2 weeks, then the patient was removed from treatment.
G-CSF (Neupogen or Neulasta) could be used prophylactically or therapeutically at the discretion of the treating physician. Recombinant erythropoietin also was allowed. Allopurinol, standard antiemetics, and prophylactic intrathecal methotrexate were used at the treating physician's discretion. External beam radiotherapy was allowed for patients with limited-stage disease at the end of chemotherapy.
The primary endpoint was to assess the safety of combination ER-CHOP. Secondary objectives included the efficacy of ER-CHOP, as defined by the CR rate, the ORR (PRs plus CRs), and PFS.
Response assessment (by the International Workshop Response Criteria) occurred after 4 cycles.31 Patients were treated until best response plus 2 additional cycles, up to a maximum of 8 cycles. If there was no response observed by Cycle 4 or if patients developed progression/recurrence at any time, then treatment was discontinued. Patients were observed for 6 months after the end of treatment. After completion of treatment and observation, patients were followed for event monitoring (recurrence and death).
Toxicity was evaluated using the National Cancer Institute Common Toxicity Criteria (version 2) standard toxicity grading. The study was designed to enroll 15 patients with the primary endpoints of grade 4 neutropenia and grade 3 infusional toxicities. With 15 patients, we would be able to estimate the incidence of the primary endpoints with a 95% confidence interval width of approximately 50%. The study was not powered on efficacy, although response and EFS were secondary events. PFS survival was defined as the time from study entry to disease progression or death. OS was defined as the time from study entry to death from any cause. Patients who had not died or progressed were censored at the last known follow-up. The distributions of PFS and OS were estimated using the Kaplan–Meier method.32
All patients underwent assessment of human antihuman antibody/human antichimeric antibody (HACA/HAHA). This was done at baseline, at the completion of therapy, and 6 months after the completion of therapy. CD22 immunostains were done on the original biopsy specimens if they were available.
Between September 2002 and September 2003, 15 patients with newly diagnosed DLBCL were enrolled onto the study; all were evaluable for safety and efficacy analysis. Baseline clinical characteristics are outlined in Table 2. The median age was 63 years, and 2/3 of patients were men. Sixty percent of patients had stage III or IV disease; and 53% of patients had extranodal disease, including gastric, bowel, bone, bone marrow, pancreas, adrenal, or vaginal involvement. Thirty-three percent of patients had elevated serum LDH, 47% had a low-risk IPI score, and 47% had intermediate-risk IPI score. Only 1 patient had a high-risk IPI or age-adjusted IPI score.
Table 2. Baseline Patient Characteristics
No. of patients
PS indicates performance status; IPI, International Prognostic Index; Aa IPI, age-adjusted IPI.
Stage I or II
Stage III or IV
In general, the treatment was tolerated well. In total, 92 treatment cycles were administered. Twelve patients completed 6 cycles, and 2 patients completed 8 cycles. One patient received only 4 cycles and then was removed from the study because of toxicity. Two patients received involved-field radiotherapy after 6 cycles for early-stage disease. Grades 3 and 4 toxicities are outlined in Table 3.
Fourteen patients (93%) developed grade 4 neutropenia, including 11 patients during the first cycle and 1 patient each during cycles 2, 3 and 4. Grade 4 neutropenia occurred in 28 of 92 cycles (30%). Three of 15 patients (20%) developed grade 3 or 4 anemia. One patient developed grade 3 thrombocytopenia.
No grade 3 antibody infusion-related toxicity was observed. Eight patients (53%) developed grade 1 or 2 toxicity characterized by fever, chills, and/or rigors. All 8 of those patients developed toxicity during the first cycle.
Five patients developed grade 4 toxicity (2 patients developed arrhythmia-atrial fibrillation, 1 patient developed a pulmonary embolus, 1 patient developed an arterial embolus, and 1 patient had a cerebrovascular accident). Three patients developed grade 3 toxicity (1 neuromotor and 2 neurosensory).
Three patients (20%) developed infection or fever. One patient developed infection without neutropenia; 1 patient developed febrile neutropenia on 2 occasions, and 1 patient had 4 episodes of infection/febrile neutropenia (1 infection without neutropenia, 1 infection with grade 3 neutropenia, and 2 episodes of febrile neutropenia). There were no deaths because of toxicity. No patients developed a positive HAHA/HACA.
Eleven patients (73%) required dose reductions, including 9 reductions because of grade 4 neutropenia despite the use of growth factors and 1 reduction because of mucositis. A man aged 78 years who had a prior history of heart disease with gastric DLBCL was removed from the study after 4 cycles because of toxicity; he developed multiple gastrointestinal bleeding, pulmonary embolus, and atrial fibrillation.
Response to Treatment
Among all 15 patients, the final assessment of response was as follows: ORR, 87%; CR, 67% (10 of 15 patients); PR, 20% (3 of 15 patients); stable disease, 7% (1 of 15 patients); and disease progression, 7% (1 of 15 patients). One patient who had only bony disease was stable by CT criteria but had a negative positron emission tomography scan and, for the purposes of response assessment criteria of the study, was classified with stable disease. One patient who had an initial response after 4 cycles subsequently progressed after 6 cycles.
At a median follow-up of 30 months, 13 of 15 patients remain alive. The 1-year PFS and OS rates were 93% and 100%, respectively, and the 2-year PFS and OS rates were 86% and 86%, respectively. The Kaplan-Meier curves of PFS and OS are shown in Figure 1. One patient progressed at 4 months (on therapy), 1 patient progressed at 28 months with follicular lymphoma, and 1 patient progressed at 35 months with recurrent DLBCL that affected cauda equina and lymphomatous meningitis. Two patients died, 1 from progressive disease after autologous stem cell transplantation and 1 from heart disease.
All tumors were positive for CD20 by immunostaining. Histology was available for 11 of 15 patients for CD22 immunostaining. All 11 patients were positive, including 2 patients who had weak positivity. Both patients with weak positivity for CD22 achieved a CR and continue in remission.
To our knowledge, this is the first study to combine epratuzumab with chemotherapy. The results from this pilot study showed that ER-CHOP therapy is a safe and effective regimen for the treatment of patients with newly diagnosed DLBCL.
DLBCL is the most common type of NHL in North America. CHOP chemotherapy was the standard of therapy for decades but has been replaced by R-CHOP. Despite the improved outcome with R-CHOP, room for improvement remains. Current strategies to improve R-CHOP include the addition of other chemotherapy drugs (etoposide in the CHOEP regimen33) or shortening the interval of treatment to every 14 days (R-CHOP1434). Our approach, adding a second monoclonal antibody, is designed to increase the efficacy without significantly increasing the toxicity.
In this pilot study, we added epratuzumab to R-CHOP for the treatment of newly diagnosed DLBCL. The ORR was 87%, and at 2 years, 86% of patients were alive without disease. This is similar to the R-CHOP data, which showed that approximately 70% were alive at 2 years in the GELA study (albeit among older patients), and 88% were alive without disease in the study by Vose et al.10, 13 In the U.S. Intergroup trial (older patients), the ORR at 2.7 years was 77% for the patients who received R-CHOP.16
The incidence of grade 4 neutropenia in the current study (93%; 14 of 15 patients) was high, but all patients recovered their blood counts in time for their next cycle except on 1 occasion, which resulted in a dose delay of 1 week. In addition, of the 14 patients who had grade 4 neutropenia, only 3 patients (20%) had infection or fever. In the study by Vose et al., the incidence of grade 4 neutropenia was 58% (19 of 24 patients), but the frequency of monitoring was not specified.10 In that study, 36% of patients required hospitalization, fever was reported in 6% of patients (2 patients), and sepsis was reported in 6% of patients (2 patients). In the GELA study, the absolute incidence of neutropenia was not reported; however, the incidence of fever and infection was not increased in the R-CHOP arm compared with the CHOP arm.13 In addition, the median nadir of neutrophil count after each cycle of therapy reportedly was similar in both groups. Growth factor therapy was given to approximately 40% of patients by the fourth cycle. In the Intergroup trial, the incidence of grade 3 or 4 neutropenia was 78% in both the R-CHOP arm and CHOP arm.15 Growth factor use was reported in 50% of patients for at least 1 cycle; overall, growth factor was used in 17% of cycles.35 Febrile neutropenia was reported in 8% of cycles. It is possible that the high incidence of grade 4 neutropenia observed in our study was caused in part by frequent (weekly) monitoring. Although the other published studies reported the incidence of neutropenia, the frequency of monitoring was not reported. Transient neutropenia has been observed with the use of rituximab either alone, with chemotherapy, or with autologous stem cell transplantation.36, 37 It is unclear whether adding immunotherapy to chemotherapy significantly increases the hematologic toxicity over chemotherapy alone. The routine use of growth factors may be indicated for prophylaxis of neutropenia when combining immunotherapy with chemotherapy.
In conclusion, ER-CHOP is associated with acceptable toxicity and does not appear to be inferior to R-CHOP. These encouraging initial results have led to a Phase II multicenter study using ER-CHOP therapy for newly diagnosed DLBCL. If the pilot study results are confirmed, then ER-CHOP will need to be compared in a randomized study in patients with DLBCL.