Study design
This is an open-label, multicenter, randomized phase III trial with two parallel arms. The study design was approved by the leading ethics committee (Ethik-Kommission Albert-Ludwigs-Universität Freiburg, Germany) and the local ethics committees of the participating centers. The protocol was also subject to authorization by the competent authorities as mandatory by federal law. All participants have to provide written informed consent. The trial was assigned the EudraCT number 2020-001181-10 and is registered at German clinical trials registry (DRKS00024085, registration date March 29th, 2023).
Study objectives and endpoints
The primary objective of this trial is to demonstrate superiority (in terms of PFS) of a shorter but more intensive treatment regimen comprising 2 cycles of MARTA (R-HD-MTX/AraC) followed by busulfan and thiotepa-based HCT-ASCT, compared to standard treatment with R-MP and procarbazine maintenance. The primary endpoint PFS is defined as time from randomization to disease progression or death of any cause, with censoring at the last date the patient was seen alive and free of disease progression.
Secondary efficacy endpoints are OS, event free survival (EFS), defined as time from randomization to premature EOT due to any reason, lymphoma progression or death, whichever occurs first, censoring at the last date the patient was seen event-free, remission rate (complete remission (CR) and partial remission (PR)) after 2 cycles of R-MP (arm A) / 2 cycles of MARTA prior to consolidation treatment (arm B) (measured at response assessment (RA) I) and after 3 cycles of R-MP (arm A) / after HCT-ASCT (arm B) (measured at RA II). Tumor response will be assessed by gadolinium-enhanced brain MRI according to the IPCG response criteria (33) and will be evaluated by central independent radiological review, not involved in the conception of the study. Secondary safety endpoints include (serious) adverse events, toxicity (according to National Cancer Institute’s Common Terminology Criteria for Adverse Events (NCI-CTCAE) v5.0), and QoL (measured by EORTC QLQ-C30 (34) and -BN20 (35)) as well as rate of unplanned hospital admissions and length of hospital stays. Additionally, neurocognitive impairment in general will be measured by Montreal Cognitive Assessment (MoCA (36)) and will be supplemented by the Trail Making Test A and B (37), the Rey-Osterrieth-Complex-Figure-Test (38) and a verbal fluency test (38) in order to assess psychomotor speed, executive functions and visuoconstruction in more detail.
Geriatric assessment
We will focus especially on establishing GA tools to help define transplant eligibility. Therefore a GA covering functional status (ADL, IADL), comorbidity (CIRS-G, CCI, HCT-CI (39)), cognitive function (MoCA), psychological state (depression PHQ9 (40), anxiety GAD7 (41)), social support (SSUK (42)), nutritional status (weight, height, weight loss questionnaire (43)) and polypharmacy (Lachs geriatric screening) domains will be checked at specific timepoints during the study.
Patient Involvement
In a pre-study phase patient’s priorities and information preferences were assessed to optimize the patient trial information in cooperation with the Department of Self-help Research of the Comprehensive Cancer Center Freiburg (CCCF). In addition, patients’ representatives of a national patient advocacy organisation (German Leukemia and Lymphoma Aid DLH) were involved to support us in improving the informed consent material of the trial. As a result, a checklist for the informed consent discussion with the patient was developed to support the study physicians. At regular intervals patients and their families will be informed about the process of the trial in patient information events. Our positive experience with the participation of patients in the pre-study phase encouraged us to involve patients’ representatives (German Leukemia and Lymphoma Aid, DLH) throughout the whole period of the clinical trial in the data monitoring committee (DMC).
Eligibility criteria
Immunocompetent patients with newly-diagnosed primary DLBCL of the central nervous system, age >70 years or age 65-70 years if not eligible for more intensive treatment (e.g. OptiMATe trial (17)) with an ECOG PS ≤ 2 are eligible. An ECOG PS > 2 due to PCNSL symptoms is also acceptable for inclusion. For further details on inclusion and exclusion criteria please see Table 1.
A special focus of the trial lies on developing tools to help define transplant eligibility, therefore additional randomization criteria were implemented after the pre-phase treatment:
1. Patients eligible for HCT-ASCT defined by the EBL score (at most one of the 3 following conditions may apply: ECOG PS > 1, Barthel Index of ADL < 20 and Lachs geriatric screening > 3), improvement of PS after pre-phase treatment or clinical judgement by the treating physician after discussion with the study expert team in a study board. Of note, for the Barthel Index of ADL the version with a maximum of 20 points will be used.
2. No evidence of disease progression after pre-phase treatment.
Table 1 Inclusion and exclusion criteria
Inclusion criteria
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- Immunocompetent patients with newly-diagnosed primary DLBCL of the central nervous system.
- Age > 70 years or age 65-70 years if not eligible for more intensive treatment (e.g. OptiMATe trial).
- Histologically or cytologically assessed diagnosis of B-cell lymphoma by local pathologist.
- Diagnostic sample obtained by stereotactic or surgical biopsy, CSF cytology examination or vitrectomy.
- Disease exclusively located in the CNS.
- At least 1 measurable lesion.
- ECOG-Performance Status ≤ 2 (ECOG PS >2 due to PCNSL symptoms is acceptable)
- Patients possibly eligible for HCT-ASCT as judged by the treating physician.
- Written informed consent obtained according to international guidelines and local laws by patient or authorized legal representative in case patient is temporarily legally not competent due to his or her disease.
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Exclusion criteria
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- Congenital or acquired immunodeficiency including HIV infection and previous organ transplantation.
- Systemic lymphoma manifestation (outside the CNS).
- Primary vitreoretinal lymphoma or primary leptomeningeal lymphoma without manifestation in the brain parenchyma or spinal cord.
- Previous or concurrent malignancies with the exception of surgically cured carcinoma in situ or other kinds of cancer without evidence of disease for at least 5 years.
- Previous systemic Non-Hodgkin lymphoma at any time.
- Inadequate renal function (creatinine clearance <60 ml/min).
- Inadequate bone marrow, cardiac, pulmonary or hepatic function according to investigator´s decision.
- Active hepatitis B or C disease.
- Concurrent treatment with other experimental drugs or participation in an interventional clinical trial with administration of study medication within the last thirty days before the start of this study.
- Third space fluid accumulation >500 ml.
- Hypersensitivity to study treatment or any component of the formulation.
- Taking any medications likely to cause interactions with the study medication.
- Known or persistent abuse of medication, drugs or alcohol.
- Active COVID-19-infection or non-compliance with the prevailing hygiene measures regarding the COVID-19 pandemic.
- Patients without legal capacity and who are unable to understand the nature, significance and consequences of the study and without designated legal representative.
- Previous participation in this trial.
- Persons who are in a relationship of dependency/employment to the sponsor and/ or investigator.
- Any familial, sociological or geographical condition potentially hampering compliance with the study protocol and follow-up schedule.
- Fertile patients refusing to use safe contraceptive methods during the study.
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Randomization methodology
Randomization will be performed after the pre-phase treatment, stratified by ECOG performance score (ECOG 0/1 vs ECOG ≥ 2), in blocks with randomly varying block sizes in a ratio of 1:1. The block lengths will be documented separately and will not be disclosed to the centers. Stratification by study center will not be performed due to a large number of centers with presumably few patients. The randomization lists will be provided by the trial biometrician and uploaded into secuTrial® by the data management. The randomization sequence will be produced by validated programs based on the Statistical Analysis System (SAS®).
A randomization form will be created in secuTrial®. Performance of randomization will be documented electronically at the study site in secuTrial® to guarantee concealment of the next treatment allocation. Randomization will take place after the pre-phase treatment once the additional randomization criteria are verified.
Treatment schedule
Figure 1 The intervention scheme shows the treatment schedule. Patients will either receive the standard treatment (Arm A) comprising 3 cycles of R-MP followed by procarbazine maintenance or the experimental treatment (Arm B) comprising 2 cycles of MARTA followed by HCT-ASCT consolidation. Treatment duration is depicted on the left (arm A) and right side (arm B). The red test tube indicates time points when samples for the translational project are to be collected (for details see translational research program).
Treatment plan
All enrolled patients will receive 1 cycle of pre-phase treatment with rituximab 375 mg/m2 and MTX 3.5 g/m2 to achieve disease stabilization and improvement of clinical PS.
Arm A (control intervention)
Patients in the control arm (arm A) receive 3 cycles of R-MP (rituximab 375 mg/m² i.v. d0,14; MTX 3,5 g/m² i.v. d1,15; procarbazine 60 mg/m²/d p.o. d2-11) every 4 weeks followed by maintenance treatment with procarbazine 100 mg absolute/d p.o. d1-5 every 4 weeks for 6 cycles (duration of maintenance treatment 6 months). Stem cell harvest will be performed after cycle 1 of R-MP according to local standard procedure. In case of unsuccessful stem cell harvest after cycle 1, further attempts can be made after cycle 2 and 3.
Arm B (experimental intervention)
Patients in the experimental arm receive 2 cycles of R-HD-MTX/AraC (rituximab 375 mg/m² i.v. d0, 4; MTX 3,5 g/m² i.v. d1, AraC 2x2 g/m²/d i.v. d2+3) every 3 weeks followed by consolidating HCT-ASCT with rituximab 375 mg/m2 d-8, busulfan 3.2 mg/kg/d i.v. d-7 and d-6 and thiotepa 5 mg/kg/d i.v. d-5 and d-4.
Stem cell harvest will be performed after cycle 1 of MARTA according to local standard procedure. In case of unsuccessful stem cell harvest after cycle 1, stem cell harvest can be performed after cycle 2.
Assessments and follow-up
The following parameters will be gathered at each visit: ECOG PS, vital signs, thorough physical and neurological examination including the NANO Scale, laboratory tests and adverse events. At screening, we will assess also premorbid PS as well as premorbid functional status. Before randomization, patients will be re-evaluated for HCT-ASCT eligibility.
Imaging evaluation by whole brain gadolinum-enhanced MRI will be conducted after cycle 2 of R-MP (arm A) / cycle 2 of MARTA (arm B) as well as after cycle 3 of R-MP (arm A) / 30 days after ASCT (arm B).
In addition to these timepoints, patients with clinical signs of progression at any time during the study treatment or if study treatment is delayed for more than 2 weeks during induction treatment will receive subsequent gadolinium-enhanced brain MRI to confirm radiologic disease status.
During follow-up gadolinium-enhanced brain MRI will be performed every 3 months in year 1-2, every 6 months in year 3-5 and annually thereafter. Tumor size and location(s) will be assessed only at screening and in case of progressive disease (PD)). Tumor number (singular/multiple) will only be assessed at screening.
Independent pathologic and radiologic review are implemented in this trial to assure high-level methodical and quality standards.
Further information on assessments during the trial and the follow-up period are given in the appendix (see supplementary material, additional file 1: trial flow chart arm A and arm B).
Translational research program
Within this trial, a comprehensive translational research program is implemented to improve our understanding of the pathogenetic factors that drive lymphomagenesis and to establish innovative biomarkers that improve risk stratification and outcome prediction. We will comprehensively explore tumor biopsies to characterize molecular subgroups of patients with certain (epi-)genetic alterations. Additionally, we will apply targeted next-generation sequencing to circulating tumor DNA (ctDNA) obtained from blood plasma and cerebrospinal fluid (CSF) throughout the treatment course to investigate its role as prognostic biomarker (Figure 1) (44).
Sample size calculation
The sample size calculation is based on the primary endpoint PFS. The control intervention is the R-MP protocol, as previously reported (10). Within the PRIMAIN study, the proportion of patients being free of lymphoma relapse/progression or death 12 months after diagnosis was about 50%. Assuming improved toxicity profile and protocol adherence by the addition of the pre-phase treatment and a greater familiarity with the protocol, we expect a higher PFS rate at 12 months of 55% for the control arm in the trial proposed herein. Results of the MARTA study report a PFS rate of about 60% at 12 months after diagnosis. Meeting the above mentioned effect of the pre-phase treatment, we conservatively expect a PFS rate above 65% (67.5% for calculation) 12 months after randomization, corresponding to hazard ratio of experimental versus control of 0.66. Considering an exponential survival time distribution, a two-sided alpha = 0.05 and power = 0.8 (recruitment time 60 months, FU time from randomization between 12 and 72 months, up to 12 months after the randomization of the last patient), 178 events on total need to be observed, and 118 patients per arm need to be randomized in a 1:1 ratio (total n=236) and need to have complete FU. To account for possible drop outs (e.g. loss of FU or violation of inclusion/exclusion criteria), we aim to randomize 260 patients. Patients lost to FU will be included in the full analysis set (FAS), but may lead to a slightly reduced treatment effect. Assumptions of the dropout rate and of the rate of registered patients not reaching randomization are also based on the results of our previous studies. The latter is expected to range around 15%, thus we plan to include 310 patients in the trial pre-phase. The program used for the calculation is nquery 7.0, the test method applied is the log-rank two group test of equal exponential survival.
Statistical analysis
The primary analysis will be performed according to the intention-to-treat (ITT) principle in the full analysis set (FAS). The FAS includes all randomized patients in whom therapy after randomization was started. Patients will be analysed in the treatment arms to which they were randomized, irrespective of whether they refused or discontinued the treatment or whether other protocol deviations are known.
The analysis of the primary endpoint PFS will be conducted in the FAS according to the intention-to-treat principle. The treatment effect will be estimated and tested by Cox regression. The regression model will include treatment and, for adjustment, the stratification variable ECOG (0/1 vs. ≥ 2) as independent variables. As estimate of the effect size, the hazard ratio (arm A vs. arm B) will be calculated with a corresponding asymptotic two-sided 95% confidence interval (CI). The two-sided test on the difference between the experimental arm A and the control arm B at two-sided significance level of 5% will be based on the corresponding asymptotic two-sided 95% CI from the Cox regression model.
Additionally, PFS rates in the two treatment arms will be estimated by the Kaplan-Meier method.
The primary analysis is conducted irrespective of the occurrence of intercurrent events, consistent with the treatment policy strategy of the estimands framework described in the ICH E9 (R1) addendum. Intercurrent events comprise early termination of treatment due to toxicity, treatment failure or patient´s wish. These events are captured in the secondary endpoint EFS in accordance with the composite strategy.
As a sensitivity analysis, the analysis will be repeated in the per-protocol (PP) set, excluding patients with major protocol violations.
Secondary endpoints will be analyzed descriptively. EFS and OS will be analyzed in the same way as described for PFS. Remission after 2 cycles of induction treatment will be determined after the 2nd cycle of R-MP in arm A and after the 2nd cycle of R-HD-MTX/AraC in arm B (= RA I in both arms). The endpoint remission after completion of the 3rd cycle of R-MP (arm A) / consolidating HCT-ASCT (arm B) will be determined within 25-35 days after the start of the 3rd cycle of R-MP (arm A) / on day 30 after ASCT (arm B).
Sensitivity analyses will be performed by additionally including other relevant prognostic variables: gender, LDH level (≤ vs. > above upper normal limit), involvement of deep structures of the brain (yes vs. no) and protein count of cerebrospinal fluid (≤ vs. > above upper normal limit), to adjust for potential confounding in the regression models proposed above for the primary and the secondary endpoints.
Safety analyses will be performed in the safety population (SAF). Patients in the SAF are analyzed as belonging to the treatment arm defined by treatment received. Patients are included in the respective treatment arm, if treatment was started.
Quality assurance and safety
The data management will be done with secuTrial® (https://www.secutrial.com/). During data entry, the data will be checked by so-called edit checks. There are study-specific reports programmed and generated with secuTrial® or SAS software that allow to check for completeness, consistency, plausibility, as well as protocol violations and other distinctive problems (e.g. cumulative missing data). All programs which can be used to influence the data or data quality will be validated.
Data monitoring committee
An independent Data Monitoring Committee (DMC) has been established, that consists of two medical scientists and one statistician with longstanding experience in clinical trials. The DMC’s function is to monitor the study’s course and if necessary, make recommendations to the coordinating or principal investigator for study continuation, modification or discontinuation. The DMC members will be informed about patient recruitment, adherence to the protocol, observed serious adverse events and deaths by receiving the development safety update reports (DSURs) at regular intervals.