Ibritumomab followed by a reduced intensity, partial T cell-depleted allogeneic stem cell transplantation and immunomodulation with lenalidomide and DLI in patients with relapsed diffuse large B-cell Non-Hodgkins lymphoma

Diffuse large B cell lymphoma
Diffuse large B-cell lymphoma (DLBCL) is the most common subtype (30-40%) of
non-hodgkin lymphoma with an incidence of approximately 700 patients each year
in The Netherlands. It is nowadays recognized as a clinically and biologically
heterogeneous disease. Based on genetic analysis different subtypes are
recognized, such as the activated B cell-like (ABC) type and the germinal
center B cell-like type (GCB), with different outcome1. For most DLBCL
cyclophosphamide, doxorubicin, vincristin, and prednisone (CHOP) chemotherapy
has been the mainstay of therapy since the 1970s with a long term survival (OS)
of approximately 40%.2 Addition of rituximab, a monoclonal antibody against the
B-cell transmembrane protein CD20, to CHOP (R-CHOP), improved the overall
survival by 10 to 15%.3 Still a significant number of patients will not be
cured at first line treatment.

Autologous stem cell transplantation
At first relapse, high-dose chemotherapy followed by autologous stem cell
transplantation (ASCT) can still establish a cure in about 45% of patients.4
The curative potential of this salvage therapy however appeared to be much
lower, only 23%, in patients already treated by rituximab in the first line,
which nowadays is standard of care.5 This suggests that the improvement in cure
rate by addition of rituximab in first line treatment has resulted in the fact
that those patients who relapse have more chemotherapy-resistant disease, and
it is more challenging to achieve a second remission. Apart from the use of
ASCT at relapse, patients with prognostic unfavorable characteristics have been
included in more aggressive treatment protocols with upfront autologous
transplantation. For patients who relapse after autologous stem cell
transplantation a palliative treatment is warranted, with -at best- a short
term remission. The median overall survival at relapse after autologous stem
cell transplantation is between 3 -4 months.6 7
Allogeneic stem cell transplantation (alloSCT) is the only potentially curative
option in the relapse setting after intensive chemotherapy and autologous
transplantation for DLBCL employing the graft-versus-lymphoma effect. Previous
studies exploring allogeneic stem cell transplantation showed an improvement on
progression free and overall survival compared to historic controls, but at the
cost of a lot of toxicity and deaths due to treatment (Non-relapse mortality
(NRM)).
This will be the first study combining radioimmunotherapy with a reduced
intensity conditioning T-cell depleted stem cell transplantation with
immunotherapy with lenalidomide and donor lymphocyte infusion (DLI) in DLBCL.
With our new concept, we hope to reduce toxicity by T cell depletion, reduce
early relapse by using conditioning with ibritumomab, and improve
progression-free survival (PFS) and overall survival by the use immunotherapy
with lenalidomide and preemptive DLI. When this study shows feasibility of the
concept, a larger multicenter randomized phase III trial will be planned.
1.2 Background Therapeutic Information

Allogeneic stem cell transplantation in DLBCL

Conventional alloSCT with myeloablative conditioning in lymphoma is accompanied
by a high non-relapse mortality (NRM) due to both infections and
graft-versus-host-disease (GVHD) and for that reason has been abandoned. The
development of reduced-intensity preparative regimens have led to lower NRM
rates.8
Several studies are published examining the effect of allogeneic
transplantation with reduced intensity conditioning (alloRIC) in lymphoma. The
majority of these studies are retrospective analyses of heterogeneous
populations including patients with Hodgkin disease and both indolent and
aggressive Non-Hodgkin lymphoma (NHL). However, some of these studies have a
relatively high number of patients with DLBCL included. In general, especially
for the DLBCL patients there was a high treatment related mortality and a low
progression free survival. Chemosensitive disease was associated with a better
outcome. Robinson et al analyzed 188 patients with lymphoma treated with
alloRIC, of whom 62 had high-grade lymphoma, with 73% of patients with
chemosensitive disease and 52% with a prior autograft. Overall survival (OS)
was 52% at 1 year, with a PFS of 32% at 1 year. Non-relapse mortality (NRM) was
30% at 1 year for these patients. 9 Armand showed retrospective results of 87
alloRIC transplants, including 23 with aggressive lymphoma. Of these 23, 78%
failed a prior autograft, which is suggestive for more resistant disease. One
and three-year OS were 69% (CI 50-88) and 42% (CI 15-70), respectively. PFS was
48% (CI 54-100) and 22% (CI 0-45) at 1 and 3 year. NRM was 17% (CI 1-33) and
39% (CI 9-69), respectively.10
Recently, a number of studies were published limited to aggressive lymphoma, 11
and limited to DLBCL 12 13 14. Maloney treated 40 lymphoma patients, 31 with
DLBCL. 52% of these patients had received a prior autograft. Results are
summarized in table 1. Seventeen patients were in complete remission (CR), and
12 had chemo-refractory disease at the time of stem cell transplantation. The
response rate was 60% in patients with chemosensitive disease, compared with
27% in patients with refractory disease. The authors conclude that disease
status and chemotherapy sensitivity are the strongest predictors of outcome. 11
Sirvent et al published the results of 68 DLBCL patients treated with
reduced-intensity stem cell transplantation. Of all patients, 79% had received
a previous autologous transplant. Forty-seven percent of patients were in
complete remission before transplantation. The NRM was 14% (95 % CI, 5% - 23%)
at 100 days and 23% (95% CI, 12%-34%) at 1 year. Sixteen patients died of
treatment related complications at a median of 127 days after transplant (range
13-1607 days). Four patients died of infections, 4 of multi-organ failure, 5 of
GvHD and 3 patients of other toxicity. Relapse occurred in 26 patients, at a
median of 3 months after transplant (range 0-55 months), with only 3 relapses
beyond 1 year posttransplant. CR status prior to transplant was associated with
a reduced relapse risk, 20% versus 62% for patients in partial remission (PR),
and 58% for patients with stable disease (SD) and progressive disease (PD).13
Rezvani et al published the results of 31 patients treated with allogeneic stem
cell transplantation in relapse DLBCL. Fifty seven percent failed autologous
stem cell transplant. Fourteen patients (44%) were in CR before transplant, 9
patients were in PR and 9 were refractory (28%). Chemosensitive disease was
again associated with better outcome (3yr OS of 56% and PFS of 43%). Relapse
occurred after a median of 77 days (21-378 days). Non relapse mortality
included 2 patients with cardiovascular disease and 1 metastatic colorectal
cancer.
Thomson et al. showed encouraging results of 48 patients with DLBCL (of whom 30
patients with de novo disease) treated with allogeneic stem cell
transplantation.14 Once more, patients with chemotherapy sensitive disease
before alloRIC had PFS and OS rates at 4 years of 55% and 54%. Also, the poor
outcome in chemotherapy refractory disease was revealed another time in this
study (12% OS and PFS after 4 years).

Consistently, all these studies show the poor outcome of patients with
refractory or progressive disease or bulky localization. As such, in this pilot
study we propose to include patients that still show chemosensitivity on a
salvage regimen, such as R-DHAP, Promacecytabom or R-PECC. Especially in case
of a MUD donor we will also need time to find a suitable donor.

T-cell depletion to reduce severity of GVHD
Major drawback in the studies mentioned above (except for the Thomson study)
was the high incidence of graft versus host disease (acute GVHD (aGVHD) 39- 55%
gr II-IV; 19-22% gr III-IV; chronic GvHD 41-47%) the major cause of the NRM
(21% after 2 years - 25% after 3 years).
Thomson et al. used conditioning with alemtuzumab in the alloRIC setting in
patients with aggressive NHL to reduce GVHD related morbidity and mortality.14
In the patients treated in this study, the incidence and severity of GvHD was
substantially lower (aGvHD 17%; cGvHD 13%), however the non-relapse mortality
was, despite of the lower incidence of graft, 32% after 4 years, mostly due to
infections. Alemtuzumab, also in the non-transplant setting is known to
severely immuno-compromise patients, due to both T-cell and B-cell depletion.
An attractive alternative seems partial T-cell depletion. Partial T
cell-depleted allogeneic stem cell transplantation followed by a preemptive
donor lymphocyte infusion (DLI) is shown to be effective in multiple myeloma 15
and is associated with a lower incidence of GvHD and a low NRM. Partial T-cell
depletion apart from diminishing GvHD, will also reduce the graft versus tumor
effect and as such has to be followed by immunotherapy. Interestingly, in a
study for multiple myeloma with partial T-cell depletion 11/24 patients
received pre emptive DLI, all 7 patients that showed long term disease free
survival and perhaps are cured were in the group that received the pre emptive
DLI.16
There have been relatively few reports of sustained clinical responses in
patients with DLBCL following a donor lymphocyte infusion (DLI) at relapse,
sometimes combined with chemotherapy.17-20 Furthermore, there are reports of
responses after withdrawal of immune suppression, confirming the graft versus
lymphoma effect. 18 On the efficacy of preemptive DLI in DLBCL are currently no
data available and this will be a major subject in this study.

Ibritumumab tiuxetan to reduce disease activity and create a window for
immunotherapy
A disadvantage of the T cell depleted scheme is the relatively long time needed
before immune therapy can be applied. First the ciclosporin has to be reduced
and stopped and one has to be sure no significant GvHD develops before
pre-emptive DLI can be given.
90Y-ibritumomab tiuxetan (Zevalin) has been shown to be fairly effective in
DLBCL in relapse setting,21 can result in long-term responses (> 3 year)22 and
as consolidation therapy it is even more promising. 23
Several studies showed the feasibility of radio-immunotherapy as part of a
conditioning regimen in autologous and allogeneic stem cell
transplantation.24-28 Radio-immunotherapy can overcome resistance to
non-labeled monoclonal antibodies. Lymphoma cells which do not bind the
antibody due to poor accessibility, such as large or poorly vascularized masses
or aberrant phenotype, can still be eliminated by the *crossfire effect* of
radiation from adjacent cells that have bound Zevalin.
Zevalin, preceding a reduced intensity induction regimen, has been shown to be
feasible, to reduce disease activity without additional toxicity, it does not
impair engraftment and as such can create a window for immunotherapy. 28
Ibirtumomab has a half-life of 64 hours.
Preliminary data show that the dose of Zevalin probably can be escalated from
0.4 to 0.6 or even to 0.8 mCi/kg.29 In this protocol we will use the 0.4 mCi/kg
dose, used in most studies published. To enhance the biodistribution of Zevalin
to the tumor in most protocols rituximab 250 mg/m2 is given immediately before
the Zevalin dose.


Immunomodulatory therapy to enhance graft versus lymphoma effect
To further improve the response and progression free and overall survival, we
will add lenalidomide, a drug known to play an immunomodulatory role.
Lenalidomide downregulates production of various critical prosurvival cytokines
in the tumor microenvironment, like tumor necrosis factor * and interleukin- 6,
while concurrently promoting the T- and natural killer cell- mediated antitumor
response. 30 Furthermore, it is shown to repair T-cell immunologic synapse
dysfunction in follicular lymphoma.31 As a single agent, lenalidomide showed
anti-lymphoma activity in a small number of patients, including DLBCL
patients.32
Since lenalidomide may enhance GVHD,33 in this protocol we will first reduce
and stop ciclosporin, and in case no significant GvHD is observed, we will
start lenalidomide at a dose of 10 mg/day. We hypothesize an immunomodulatory
effect on the residual tumor, if no GVHD is observed within 4 weeks this will
be followed by pre-emptive DLI.
The aim of the study
The aim of our study is to prove the feasibility of the concept. The primary
endpoint will be Non relapse mortality after 7 months. Secondary endpoints
comprise evaluation of safety based on GvHD > grade II and infection,
progression free and overall survival and engraftment.

2.1 Primary objective
* To determine the feasibility (as measured by non-relapse mortality after 7
months) of the regimen of Ibritumomab, followed by a reduced intensity, partial
T cell-depleted allogeneic stem cell transplantation and immunomodulation with
lenalidomide and DLI in patients with relapsed diffuse large B-cell
Non-Hodgkin*s lymphoma
2.2 Secondary Objectives
* To determine the feasibility of the proposed regimen by measurement of GvHD
* To determine the feasibility of the proposed regimen by measurement of
infections * grade 3 according to CTCAE 4.0.
* To determine the percentage of patient with graft failure
* To describe the progression free and overall survival of patients
* To explore the effect of lenalidomide and DLI after T cell depleted stem cell
transplantation on the T and NK cells
* To explore relationships between different subtypes of DLBCL /
immunohistochemical markers and progression free survival/ GvHD

The study will be an (open label) single center, single arm phase II
feasibility trial, with the endpoint being non-relapse mortality. It is the
first phase of a one-stage Simon design. The estimated accrual for this study
is 1 patient in 2 months. Thus, patient accrual is expected to be completed
within 24 months. Additional time is required to allow the response data to
mature.

Agent
Dose/day Route of administration Days
rituximab
250 mg/m2 Intravenously -14
Ibritumomab
0,4 mCi/kg Intravenously -14
Cyclophosphamide 1200
mg/m2 Intravenously -5 -4,-3,-2
Fludarabine
30 mg/m2 Intravenously -5 -4,-3,-2
Ciclosporin
6 mg /kg in 2 dosis Orally -1 (taper from wk 4, stop wk 8)
Stem cell infusion CD3/CD19 depleted 5-10 x 10*6 CD34
cells Intravenously day 0
Lenalidomide 10 mg, 21
days q 28 days Orally Week 10 to 30
DLI
0,5 x 10*6 CD3 cells/kg Intravenously Week 18

In case of a MUD donor ATG is added between cyclophosphomide/fludarabine and
stemcell infusion

In this patient population with an extreme dismal prognosis a potentially
curative therapy is offered. Patients have a risk of treatment related
mortality, but by the use of T cell depletion this will hopefully be less than
in previous studies. (between 21 and 32 % after 2-4 years). Patients will
frequently have to visit the hospital during the study, and there will be one
planned admission for conditioning chemotherapy.There is a risk of GvHD and
infections due to use of immunosuppressants.