Pharmacotherapeutic group: antineoplastic agents, monoclonal antibodies and antibody drug conjugates, ATC code: L01FA01
MabThera subcutaneous formulation contains recombinant human hyaluronidase (rHuPH20), an enzyme used to increase the dispersion and absorption of co-administered substances when administered subcutaneously.
Mechanism of action
Rituximab binds specifically to the transmembrane antigen, CD20, a non-glycosylated phosphoprotein, located on pre-B and mature B lymphocytes. The antigen is expressed on > 95% of all B-cell non-Hodgkin's lymphomas.
CD20 is found on both normal and malignant B-cells, but not on haematopoietic stem cells, pro-B-cells, normal plasma cells or other normal tissue. This antigen does not internalise upon antibody binding and is not shed from the cell surface. CD20 does not circulate in the plasma as a free antigen and, thus, does not compete for antibody binding.
The Fab domain of rituximab binds to the CD20 antigen on B lymphocytes and the Fc domain can recruit immune effector functions to mediate B-cell lysis. Possible mechanisms of effector-mediated cell lysis include complement-dependent cytotoxicity (CDC) resulting from C1q binding, and antibody-dependent cellular cytotoxicity (ADCC) mediated by one or more of the Fcγ receptors on the surface of granulocytes, macrophages and NK cells. Rituximab binding to CD20 antigen on B lymphocytes has also been demonstrated to induce cell death via apoptosis.
Pharmacodynamic effects
Peripheral B-cell counts declined below normal following completion of the first dose of MabThera. In patients treated for haematological malignancies, B-cell recovery began within 6 months of treatment and generally returned to normal levels within 12 months after completion of therapy, although in some patients this may take longer (up to a median recovery time of 23 months post-induction therapy). In rheumatoid arthritis patients, immediate depletion of B-cells in the peripheral blood was observed following two infusions of 1000 mg MabThera separated by a 14-day interval. Peripheral blood B-cell counts begin to increase from Week 24 and evidence for repopulation is observed in the majority of patients by Week 40, whether MabThera was administered as monotherapy or in combination with methotrexate.
Clinical efficacy and safety
Clinical efficacy and safety of MabThera subcutaneous formulation in non-Hodgkin's lymphoma
The clinical efficacy and safety of MabThera subcutaneous formulation in non-Hodgkin's lymphoma is based on data from a phase III clinical trial (SABRINA BO22334) in patients with follicular lymphoma (FL) and a phase Ib dose-finding/dose-confirmation trial (SparkThera BP22333) in patients with FL. Results from trial BP22333 are presented in section 5.2.
Trial BO22334 (SABRINA)
A two-stage phase III, international, multi-centre, randomised, controlled, open-label trial was conducted in patients with previously untreated follicular lymphoma, to investigate the non-inferiority of the pharmacokinetic profile, together with efficacy and safety of MabThera subcutaneous formulation in combination with CHOP or CVP versus MabThera intravenous formulation in combination with CHOP or CVP.
The objective of the first stage was to establish the rituximab subcutaneous dose that resulted in comparable MabThera subcutaneous formulation serum Ctrough levels compared with MabThera intravenous formulation, when given as part of induction treatment every 3 weeks (see section 5.2).
Stage 1 enrolled previously untreated patients (n=127) CD20-positive, Follicular Lymphoma (FL) Grade 1, 2 or 3a.
The objective of stage 2 was to provide additional efficacy and safety data for subcutaneous rituximab compared with rituximab intravenous using the 1400 mg subcutaneous dose established in stage 1. Previously untreated patients with CD20-positive, Follicular Lymphoma Grade 1, 2 or 3a (n=283) were enrolled in the stage 2.
The overall trial design was identical among both stages and patients were randomised into the following two treatment groups:
• MabThera subcutaneous formulation (n= 205): first cycle MabThera intravenous formulation plus 7 cycles of MabThera subcutaneous formulation in combination with up to 8 cycles of CHOP or CVP chemotherapy administered every 3 weeks.
MabThera intravenous formulation was used at the standard dose of 375 mg/m2 body surface area.
MabThera subcutaneous formulation was given at a fixed dose of 1400 mg.
Patients achieving at least partial response (PR) were entered on the MabThera subcutaneous formulation maintenance therapy once every 8 weeks for 24 months.
• MabThera intravenous formulation (n= 205): 8 cycles of MabThera intravenous formulation in combination with up to 8 cycles of CHOP or CVP chemotherapy administered every 3 weeks.
MabThera intravenous formulation was used at the standard dose of 375 mg/m2.
Patients achieving at least PR were entered on MabThera intravenous formulation maintenance therapy once every 8 weeks for 24 months.
Key efficacy results for the pooled analysis of 410 patients in SABRINA stages 1 and 2 are shown in Table 2
Table 2 Efficacy results for SABRINA (BO22334) (Intent to Treat Population)
| | Pooled Stages 1 & 2 N = 410 |
| Rituximab intravenous formulation (n = 205) | Rituximab subcutaneous formulation (n = 205) |
| ORR a | Point estimate | 84.9% (n = 174) | 84.4% (n = 173) |
| 95% CI | [79.2%, 89.5%] | [78.7%, 89.1%] |
| CRR | Point estimate | 31.7% (n = 65) | 32.2% (n = 66) |
| 95% CI | [25.4%, 38.6%] | [25.9%, 39.1%] |
| PFSb | Proportion with PFS event | 34.6% (n = 71) | 31.7% (n = 65) |
| Hazard ratio (95% CI) | 0.90 [0.64%, 1.26%] |
ORR – Overall Response Rate
CRR – Complete Response Rate
PFS – Progression-Free Survival (proportion with event, disease progression/relapse or death from any cause)
a – at end of Induction
b – at time of final analysis (median follow-up 58 months)
Exploratory analyses showed response rates among BSA, chemotherapy and gender subgroups were not notably different from the ITT population.
Immunogenicity
Data from the development programme of MabThera subcutaneous formulation indicate that the formation of anti-rituximab antibodies after subcutaneous administration is comparable with that observed after intravenous administration. In the SABRINA trial (BO22334) the incidence of treatment-induced/enhanced anti-rituximab antibodies was low and similar in the intravenous and subcutaneous groups (1.9% vs. 2%, respectively). The incidence of treatment-induced/enhanced anti-rHuPH20 antibodies was 8% in the intravenous group compared with 15% in the subcutaneous group, and none of the patients who tested positive for anti-rHuPH20 antibodies tested positive for neutralising antibodies.
The overall proportion of patients found to have anti-rHuPH20 antibodies remained generally constant over the follow-up period in both cohorts. The clinical relevance of the development of anti-rituximab antibodies or anti-rHuPH20 antibodies after treatment with MabThera subcutaneous formulation is not known.
There was no apparent impact of the presence of anti-rituximab or anti-rHuPH20 antibodies on safety or efficacy.
Clinical efficacy and safety of MabThera concentrate for solution for infusion in non-Hodgkin's lymphoma
Follicular lymphoma
Initial treatment in combination with chemotherapy
In an open-label randomised trial, a total of 322 previously untreated patients with follicular lymphoma were randomised to receive either CVP chemotherapy (cyclophosphamide 750 mg/m2, vincristine 1.4 mg/m2 up to a maximum of 2 mg on Day 1, and prednisolone 40 mg/m2/day on Days 1 -5) every 3 weeks for 8 cycles or MabThera 375 mg/m2 in combination with CVP (R-CVP). MabThera was administered on the first day of each treatment cycle. A total of 321 patients (162 R-CVP, 159 CVP) received therapy and were analysed for efficacy. The median follow-up of patients was 53 months. R-CVP led to a significant benefit over CVP for the primary endpoint, time to treatment failure (27 months vs. 6.6 months, p < 0.0001, log-rank test). The proportion of patients with a tumour response (CR, CRu, PR) was significantly higher (p < 0.0001 Chi-Square test) in the R-CVP group (80.9%) than the CVP group (57.2%). Treatment with R-CVP significantly prolonged the time to disease progression or death compared to CVP, 33.6 months and 14.7 months, respectively (p < 0.0001, log-rank test). The median duration of response was 37.7 months in the R-CVP group and was 13.5 months in the CVP group (p < 0.0001, log-rank test).
The difference between the treatment groups with respect to overall survival showed a significant clinical difference (p=0.029, log-rank test stratified by centre): survival rates at 53 months were 80.9% for patients in the R-CVP group compared to 71.1% for patients in the CVP group.
Results from three other randomised trials using MabThera in combination with chemotherapy regimen other than CVP (CHOP, MCP, CHVP/Interferon-α) have also demonstrated significant improvements in response rates, time-dependent parameters as well as in overall survival. Key results from all four trials are summarised in Table 3.
Table 3 Summary of key results from four phase III randomised trials evaluating the benefit of MabThera with different chemotherapy regimens in follicular lymphoma
| Trial | Treatment, N | Median FU, months | ORR, % | CR, % | Median TTF/PFS/ EFS mo | OS rates, % |
| M39021 | CVP, 159 R-CVP, 162 | 53 | 57 81 | 10 41 | Median TTP: 14.7 33.6 P < 0.0001 | 53-months 71.1 80.9 p = 0.029 |
| GLSG'00 | CHOP, 205 R-CHOP, 223 | 18 | 90 96 | 17 20 | Median TTF: 2.6 years Not reached p < 0.001 | 18-months 90 95 p = 0.016 |
| OSHO-39 | MCP, 96 R-MCP, 105 | 47 | 75 92 | 25 50 | Median PFS: 28.8 Not reached p < 0.0001 | 48-months 74 87 p = 0.0096 |
| FL2000 | CHVP-IFN, 183 R-CHVP-IFN, 175 | 42 | 85 94 | 49 76 | Median EFS: 36 Not reached p < 0.0001 | 42-months 84 91 p = 0.029 |
EFS – Event Free Survival
TTP – Time to progression or death
PFS – Progression-Free Survival
TTF – Time to Treatment Failure
OS rates – survival rates at the time of the analyses
Maintenance therapy
Previously untreated follicular lymphoma
In a prospective, open label, international, multi-centre, phase III trial 1193 patients with previously untreated advanced follicular lymphoma received induction therapy with R-CHOP (n=881), R-CVP (n=268) or R-FCM (n=44), according to the investigators' choice. A total of 1078 patients responded to induction therapy, of which 1018 were randomised to MabThera maintenance therapy (n=505) or observation (n=513). The two treatment groups were well balanced with regards to baseline characteristics and disease status. MabThera maintenance treatment consisted of a single infusion of MabThera at 375 mg/m2 body surface area given every 2 months until disease progression or for a maximum period of two years.
The pre-specified primary analysis was conducted at a median observation time of 25 months from randomisation, maintenance therapy with MabThera resulted in a clinically relevant and statistically significant improvement in the primary endpoint of investigator assessed progression-free survival (PFS) as compared to observation in patients with previously untreated follicular lymphoma (Table 4).
Significant benefit from maintenance treatment with MabThera was also seen for the secondary endpoints event-free survival (EFS), time to next anti-lymphoma treatment (TNLT) time to next chemotherapy (TNCT) and overall response rate (ORR) in the primary analysis (Table 4).
Data from extended follow-up of patients in the study (median follow-up 9 years) confirmed the long-term benefit of MabThera maintenance therapy in terms of PFS, EFS, TNLT and TNCT (Table 4).
Table 4 Overview of efficacy results for MabThera maintenance vs. observation at the protocol-defined primary analysis and after 9 years median follow-up (final analysis)
| | Primary analysis (median FU: 25 months) | Final analysis (median FU: 9.0 years) |
| Observation N=513 | MabThera N=505 | Observation N=513 | MabThera N=505 |
| Primary efficacy | | | | |
| Progression-free survival (median) | NR | NR | 4.06 years | 10.49 years |
| log-rank p value | < 0.0001 | < 0.0001 |
| hazard ratio (95% CI) risk reduction | 0.50 (0.39, 0.64) 50% | 0.61 (0.52, 0.73) 39% |
| Secondary efficacy | | | | |
| Overall survival (median) | NR | NR | NR | NR |
| log-rank p value | 0.7246 | 0.7948 |
| hazard ratio (95% CI) risk reduction | 0.89 (0.45, 1.74) 11% | 1.04 (0.77, 1.40) -6% |
| Event-free survival (median) | 38 months | NR | 4.04 years | 9.25 years |
| log-rank p value | < 0.0001 | < 0.0001 |
| hazard ratio (95% CI) risk reduction | 0.54 (0.43, 0.69) 46% | 0.64 (0.54, 0.76) 36% |
| TNLT (median) | NR | NR | 6.11 years | NR |
| log-rank p value | 0.0003 | <0.0001 |
| hazard ratio (95% CI) risk reduction | 0.61 (0.46, 0.80) 39% | 0.66 (0.55, 0.78) 34% |
| TNCT (median) | NR | NR | 9.32 years | NR |
| log-rank p value | 0.0011 | 0.0004 |
| hazard ratio (95% CI) risk reduction | 0.60 (0.44, 0.82) 40% | 0.71 (0.59, 0.86) 39% |
| Overall response rate* | 55% | 74% | 61% | 79% |
| chi-squared test p value | < 0.0001 | < 0.0001 |
| odds ratio (95% CI) | 2.33 (1.73, 3.15) | 2.43 (1.84, 3.22) |
| Complete response (CR/CRu) rate* | 48% | 67% | 53% | 72% |
| chi-squared test p value | < 0.0001 | < 0.0001 |
| odds ratio (95% CI) | 2.21 (1.65, 2.94) | 2.34 (1.80, 3.03) |
* at end of maintenance/observation; final analysis results based on median follow-up of 73 months.
FU: follow-up; NR: not reached at time of clinical cut off, TNCT: time to next chemotherapy treatment; TNLT: time to next anti lymphoma treatment.
MabThera maintenance treatment provided consistent benefit in all predefined subgroups tested: gender (male, female), age (< 60 years, >= 60 years), FLIPI score (<=1, 2 or >= 3), induction therapy (R-CHOP, R-CVP or R-FCM) and regardless of the quality of response to induction treatment (CR/CRu or PR). Exploratory analyses of the benefit of maintenance treatment showed a less pronounced effect in elderly patients (> 70 years of age), however sample sizes were small.
Relapsed/Refractory follicular lymphoma
In a prospective, open label, international, multi-centre, phase III trial, 465 patients with relapsed/refractory follicular lymphoma were randomised in a first step to induction therapy with either CHOP (cyclophosphamide, doxorubicin, vincristine, prednisolone; n=231) or MabThera plus CHOP (R-CHOP, n=234). The two treatment groups were well balanced with regard to baseline characteristics and disease status. A total of 334 patients achieving a complete or partial remission following induction therapy were randomised in a second step to MabThera maintenance therapy (n=167) or observation (n=167). MabThera maintenance treatment consisted of a single infusion of MabThera at 375 mg/m2 body surface area given every 3 months until disease progression or for a maximum period of two years.
The final efficacy analysis included all patients randomised to both parts of the trial. After a median observation time of 31 months for patients randomised to the induction phase, R-CHOP significantly improved the outcome of patients with relapsed/refractory follicular lymphoma when compared to CHOP (see Table 5).
Table 5 Induction phase: overview of efficacy results for CHOP vs. R-CHOP (31 months median observation time)
| | CHOP | R-CHOP | p-value | Risk Reduction1) |
| Primary efficacy | | | | |
| ORR2) | 74% | 87% | 0.0003 | Na |
| CR2) | 16% | 29% | 0.0005 | Na |
| PR2) | 58% | 58% | 0.9449 | Na |
1) Estimates were calculated by hazard ratios
2) Last tumour response as assessed by the investigator. The “primary” statistical test for “response” was the trend test of CR versus PR versus non-response (p < 0.0001)
Abbreviations: NA, not available; ORR: overall response rate; CR: complete response; PR: partial response
For patients randomised to the maintenance phase of the trial, the median observation time was 28 months from maintenance randomisation. Maintenance treatment with MabThera led to a clinically relevant and statistically significant improvement in the primary endpoint, PFS, (time from maintenance randomisation to relapse, disease progression or death) when compared to observation alone (p< 0.0001 log-rank test). The median PFS was 42.2 months in the MabThera maintenance arm compared to 14.3 months in the observation arm. Using a cox regression analysis, the risk of experiencing progressive disease or death was reduced by 61% with MabThera maintenance treatment when compared to observation (95% CI; 45%-72%). Kaplan-Meier estimated progression-free rates at 12 months were 78% in the MabThera maintenance group vs. 57% in the observation group. An analysis of overall survival confirmed the significant benefit of MabThera maintenance over observation (p=0.0039 log-rank test). MabThera maintenance treatment reduced the risk of death by 56% (95% CI; 22%-75%).
Table 6 Maintenance phase: overview of efficacy results MabThera vs. observation (28 months median observation time)
| Efficacy Parameter | Kaplan-Meier Estimate of Median Time to Event (Months) | Risk Reduction |
| Observation (N = 167) | MabThera (N=167) | Log-Rank p value |
| Progression-free survival (PFS) | 14.3 | 42.2 | < 0.0001 | 61% |
| Overall survival | NR | NR | 0.0039 | 56% |
| Time to new lymphoma treatment | 20.1 | 38.8 | < 0.0001 | 50% |
| Disease-free survivala | 16.5 | 53.7 | 0.0003 | 67% |
| Subgroup analysis | | | | |
| PFS CHOP R-CHOP CR PR OS CHOP R-CHOP | 11.6 22.1 14.3 14.3 NR NR | 37.5 51.9 52.8 37.8 NR NR | < 0.0001 0.0071 0.0008 < 0.0001 0.0348 0.0482 | 71% 46% 64% 54% 55% 56% |
NR: not reached; a: only applicable to patients achieving a CR
The benefit of MabThera maintenance treatment was confirmed in all subgroups analysed, regardless of induction regimen (CHOP or R-CHOP) or quality of response to induction treatment (CR or PR) (Table 6). MabThera maintenance treatment significantly prolonged median PFS in patients responding to CHOP induction therapy (median PFS 37.5 months vs. 11.6 months, p< 0.0001) as well as in those responding to R-CHOP induction (median PFS 51.9 months vs. 22.1 months, p=0.0071). Although subgroups were small, MabThera maintenance treatment provided a significant benefit in terms of overall survival for both patients responding to CHOP and patients responding to R-CHOP, although longer follow-up is required to confirm this observation.
Diffuse large B-cell non-Hodgkin's lymphoma
In a randomised, open-label trial, a total of 399 previously untreated elderly patients (age 60 to 80 years) with diffuse large B-cell lymphoma received standard CHOP chemotherapy (cyclophosphamide 750 mg/m2, doxorubicin 50 mg/m2, vincristine 1.4 mg/m2 up to a maximum of 2 mg on Day 1, and prednisolone 40 mg/m2/day on Days 1-5) every 3 weeks for eight cycles, or MabThera 375 mg/m2 plus CHOP (R-CHOP). MabThera was administered on the first day of the treatment cycle.
The final efficacy analysis included all randomised patients (197 CHOP, 202 R-CHOP), and had a median follow-up duration of approximately 31 months. The two treatment groups were well balanced in baseline disease characteristics and disease status. The final analysis confirmed that R-CHOP treatment was associated with a clinically relevant and statistically significant improvement in the duration of event-free survival (the primary efficacy parameter; where events were death, relapse or progression of lymphoma, or institution of a new anti-lymphoma treatment) (p = 0.0001). Kaplan Meier estimates of the median duration of event-free survival were 35 months in the R-CHOP arm compared to 13 months in the CHOP arm, representing a risk reduction of 41%. At 24 months, estimates for overall survival were 68.2% in the R-CHOP arm compared to 57.4% in the CHOP arm. A subsequent analysis of the duration of overall survival, carried out with a median follow-up duration of 60 months, confirmed the benefit of R-CHOP over CHOP treatment (p=0.0071), representing a risk reduction of 32%.
The analysis of all secondary parameters (response rates, progression-free survival, disease-free survival, duration of response) verified the treatment effect of R-CHOP compared to CHOP. The complete response rate after cycle 8 was 76.2% in the R-CHOP group and 62.4% in the CHOP group (p=0.0028). The risk of disease progression was reduced by 46% and the risk of relapse by 51%.
In all patient subgroups (gender, age, age adjusted IPI, Ann Arbor stage, ECOG, β2 microglobulin, LDH, albumin, B symptoms, bulky disease, extranodal sites, bone marrow involvement), the risk ratios for event-free survival and overall survival (R-CHOP compared with CHOP) were less than 0.83 and 0.95 respectively. R-CHOP was associated with improvements in outcome for both high- and low-risk patients according to age adjusted IPI.
Clinical laboratory findings
Of 67 patients evaluated for HAMA, no responses were noted. Of 356 patients evaluated for ADA, 1.1% (4 patients) were positive.
Paediatric population
The European Medicines Agency has waived the obligation to submit the results of studies with rituximab in all subsets of the paediatric population with follicular lymphoma. See Section 4.2 for information on paediatric use.