Post-transplant lymphoproliferative diseases (PTLD) are heteroge- neous lymphoid disorders ranging from indolent polyclonal prolifer- ations to aggressive lymphomas, which may complicate solid organ transplantation (SOT) or haematopoietic stem cell transplantation . The highest risk of SOT-related PTLD occurs in heart or lung (up to 20 %) transplant recipients, while the risk is lower (1-5%) in liver and renal ones, where inferior and shorter doses of immunosuppres- sors are used [1,2].
Most PTLD cases are of B cell origin (> 85-90%) and Epstein Barr Virus (EBV) is associated in two thirds of these. While EBV-negative PTLD tends to occur in older patients, with a longer latency after SOT (> 5 years versus 6−12 months in EBV+ patients) [3,4], no differences in response or survival have been described . The standard of care for PTLD has traditionally involved reduction of immunosuppressive treatment and rituximab-based chemotherapy regimens . Patients refractory to rituximab have dire prognosis and other approaches are justiﬁed . Speciﬁc cytotoxic T-lymphocytes infusions have been * Corresponding author.
E-mail address: firstname.lastname@example.org (R. Hernani).
successfully used in EBV-related PTLD, although their availability is limited .
CD19 chimeric antigen receptor T-cell (CAR-T) therapy has shown remarkable efﬁcacy in patients with relapsed or refractory diffuse large B-cell lymphoma (DLBCL) [8,9]. However, data on outcomes of CAR-T in the setting of PTLD are scarce [10−15]. Moreover, limited information is available on the inﬂuence of concomitant immunosup- pressive drugs on CAR-T function [16,17].
Herein we describe management of a patient treated with CAR-T therapy for PTLD after renal transplantation. Additionally, we suggest a strategy for minimizing immunosuppressive treatment in this clini- cal scenario. This report also reviews the limited published data in the setting of SOT-related PTLD treated with CAR-T.
Both cytokine release syndrome (CRS) and immune effector cell- associated neurotoxicity syndrome (ICANS) were graded according to the American Society for Transplantation and Cellular Therapy con- sensus . Assessment of response to CAR-T therapy was based on the LYRIC criteria . Infectious prophylaxis followed Spanish con- sensus guidelines . Cytopenias were graded according to the Common Terminology Criteria for Adverse Events v5.0 scale. To access data for the review process, a search was performed in PubMed using the search terms “post-transplant lymphoproliferative disease”, “PTLD”, “chimeric antigen receptor T-cell” and “CAR-T”. Oral presentations from Haematology conferences since 2017 (not Pubmed-indexed) were also included. Informed consent was obtained from the patient to use his clinical information for research purposes.
A 56-year-old male was diagnosed with DLBCL (EBV negative, ger- minal center phenotype, no c-Myc rearrangement) in 2017. In 2000, he had undergone cadaveric renal transplantation due to end-stage kidney disease of unknown etiology. At the time of PTLD diagnosis, his immunosuppression regimen included tacrolimus, mycopheno- late mofetil (MMF) and prednisone (5 mg/day). Both tacrolimus and MMF were switched to everolimus (1.25 mg/12 h) after diagnosis (target levels: 3.5−5 ng/ml) and prednisone was maintained. Protein- uria (1.92 g/24 h) was detected two years after everolimus conver- sion, which responded well to angiotensin converting enzyme inhibitors (ACEI). He had stage IV disease with peritoneal inﬁltration and an international prognostic index (IPI) of 3. The patient received six courses of rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP), and two additional doses of rituximab, achieving complete response (CR), as assessed by positron emission tomography (PET). Five months later, biopsy of an enlarged iliac adenopathy conﬁrmed disease recurrence, for which the patient was given two cycles of rituximab, ifosfamide, carboplatin and etoposide (R-ICE) salvage therapy, achieving CR2. Despite the absence of mor- phologic bone marrow inﬁltration by lymphoma, the patient remained with persistent cytopenias that precluded the mobilization of autologous stem cells. At that time, the patient was not eligible for allotransplant due to lack of a suitable donor. Four courses of dose- adjusted rituximab, gemcitabine and oxaliplatin (R-GEMOX) were therefore prescribed as consolidation therapy. Despite this, a PET scan performed two months later showed supra- and infradiaphrag- matic progression that was conﬁrmed by tissue biopsy. Polatuzumab, bendamustine and rituximab (PBR) were administered (only ﬁve cycles due to haematological toxicity), reaching CR3. Six months later, an isolated inguinal relapse was again conﬁrmed by PET scan. He underwent radiation therapy (30 Gy), but posttreatment evalua- tion showed infradiaphragmatic progression (stage II, IPI 1).
We decided to proceed to CAR-T therapy, selecting axicabtagene ciloleucel (Axi-cel) for two reasons: ﬁrstly, because despite a shorter duration, CD28 costimulatory domain seems to produce a more intense signalling than 4-1BB , and secondly, since reintroduction of immunosuppressive agents might be required after CAR-T if graft rejection was suspected. Everolimus was temporally discontinued before apheresis (following Kite@ instructions) and then deﬁnitively stopped before CAR-T infusion. Prednisone was maintained at physi- ological dose during the entire process avoid adrenal insufﬁciency. Bridging therapy with 2 cycles of cyclophosphamide (500 mg/m2 day 1) and prednisone (60 mg/m2 day 1−5) was prescribed. PET-scan
after bridging therapy demonstrated peritoneal progression (Deau- ville score 5), despite which it was decided to procced to CAR-T ther- apy. At the time of CAR-T infusion, creatinine, glomerular ﬁltration rate (Cockcroft-Gault Equation) and 24-h urine protein were 1.35 mg/dL, 56.7 mL/min and 0.06 g, respectively.
Clinical course after CAR-T therapy
Time from apheresis to CAR-T infusion was 64 days. The patient received the standard lymphodepleting chemotherapy regimen con- sisting of three days of FluCy (dose-adjusted ﬂudarabine 24 mg/m2/d and cyclophosphamide 500 mg/m2/d). Axi-cel was ﬁnally administered in August 2020. The patient developed grade I CRS, from day +1 to +10, which resolved after one dose of tocilizumab. He also developed grade II ICANS on day +7, which resolved immediately after initiating dexamethasone (10 mg with subsequent tapering over seven days, with a cumulative dose of 70 mg). Kidney function was closely monitored, as were inﬂammatory markers including c-reac- tive protein, procalcitonin, ferritin and interleukin-6, reaching peak levels of 114 mg/L, 0.72 ng/mL, 1428 ng/mL and 1715 pg/mL, respec- tively. No impairment of renal function was detected, and the patient was ﬁnally discharged on day +14. However, clinical course was sud- denly complicated by a septic shock and right lower lobe pneumonia due to Pseudomonas aeruginosa, that required intensive care unit admission for vasopressor support. On day +90 cytomegalovirus infection was detected, which resolved spontaneously without pre- emptive therapy. During the following weeks, the patient experi- enced grade 3 anaemia and grade 4 thrombocytopenia and neutrope- nia, which were managed with cytokine combination therapy with darbopoetin alfa (150 mg/week), eltrombopag (50 mg/day), and gran-
ulocyte colony-stimulating factor (480 mg 2−3 times per week). Bone marrow was hypocellular without dysplasia or signs of viral infection or hemophagocytic lymphohistiocytosis. Creatinine and glomerular ﬁltration rate have remained relatively stable (1.31 mg/dL and 60 mL/min at last follow-up). Signiﬁcant 24-h proteinuria was detected three months after CAR-T infusion (0.6 g), reaching a peak one month later (1.25 g). It is progressively responding to ACEI (0.84 g after two months). If worsening, a graft-biopsy will be planned to discard graft rejection. At one month after CART infusion, the patient achieved CR disease status, and this response was sus- tained up to the last follow-up (10 months).
Tailoring immunosuppressive treatment and renal monitoring during
Everolimus was not reintroduced after CAR-T therapy. Both clini- cal and analytical parameters were closely monitored for signs of graft rejection (typically manifesting as hypertension and protein- uria) or indirect markers of increased risk of graft rejection (develop- ment of anti-HLA antibodies, recovery of B lymphocytes or plasma cells). Prednisone at physiological dose was discontinued two months after CAR-T infusion, without subsequent signs of adrenal insufﬁ- ciency. CAR-T lymphocytes were detected by ﬂow cytometry up to three months after infusion, in keeping with previous data [21,22]. At last follow-up, no clear signs of graft rejection had developed, and the patient continues without immunosuppressive treatment.
Table 1 summarizes available data on the use of CAR-T for PTLD after SOT (n = 12) [10−15]. As can be seen, EBV was only associated in 2 cases (17%), which appeared soon after transplant (4 and 21 months). Kidney and liver transplants were the most frequent (7 and 3, respectively) and DLBCL was the predominant histology (n = 11 [92%]). Notably, ﬁve patients completely discontinued immunosup- pressive drugs before or soon after CAR-T infusion. Despite the short observation period, one case of graft rejection was documented. The patient remained in CR and it was decided not to reintroduce immu- nosuppressive therapy in order to reduce the relapse risk. Ten patients developed CRS (grade I - II [n = 9]; grade III [n = 1]), and four patients developed ICANS (grade III [n = 3]; grade IV [n = 1]). One patient with disease persistence died at day +115 of unclariﬁed encephalopathy, whereas the other two other patients died of infec- tion and progressive disease, respectively. Complete remission was achieved in seven patients (58%), all of them still alive and ﬁve in ongoing response.
Very few cases have been reported on CAR-T therapy for PTLD after solid organ transplantation. Here, we have described the clinical outcome of one further patient and propose a strategy for tailoring immunosuppressive treatment and organ monitoring in patients with kidney allografts after CAR-T infusion, to add to the limited body of evidence-based medical literature.
CAR-T therapy was decided in our patient after refractoriness to several lines of immunochemotherapy and non-transplant-eligible status. We were concerned that concomitant use of immunosuppres- sors prior to apheresis or after CAR-T infusion could theoretically suppress expansion of CAR-T lymphocytes , an thus increase the relapse rate . Nonetheless, partial reduction or total discontinua- tion of immunosuppressive therapy would pose the risk of enhancing the allo-immune response and leading to chronic-graft rejection [23,24], mainly due to humoral mechanisms, typiﬁed by hyperten- sion and renal dysfunction (detected by a serum creatinine increase or the appearance of proteinuria).
After discussing the abovementioned issues within a multidisci- plinary team of nephrologists and clinical and laboratory haematolo- gists, it was decided to discontinue immunosuppressive agents before CAR-T infusion in order to enhance expansion and capability to reduce disease relapse. It is worth noting that no antiHLA antigens, plasma cells or B lymphocytes were detected before infusion. We hypothesized that the immune pathways that could induce allo-graft rejection would be heavily suppressed, presumably as a result of pre- vious treatments . In light of this, immunosuppressors were no longer used and close monitoring was carried out (Fig. 1) to detect preliminary signs of rejection. Seven months after infusion the patient remains in CR without immunosuppressive drugs. Proteinuria has been detected, but it is progressively decreasing after starting ACEI.
The present data, together with previous reports, suggest that CAR-T is an effective treatment for PTLD, without severe toxicity and capable of inducing sustained responses. Speciﬁc further research in this patient subset is currently underway [26,27]. Although Luttwak et al found no alterations in CAR-T expansion despite concomitant immunosuppressive therapy , reduction or complete discontinu- ation of immunosuppressive treatment remains the ﬁrst step to treat PTLD. According to published data and our own experience, it may be feasible to completely discontinue immunosuppressive therapy, although more data and longer follow-up are required to conﬁrm this hypothesis. A close monitoring of graft function and immune reconstitution might herald an indication to reintroduce the immu- nosuppressive treatment.
Parallel to the growing use of CAR-T therapy, the number of kid- ney transplants is also rising annually (http://www.transplant-obser vatory.org), which might increase the number of CAR-T procedures offered to PTLD. The ﬁnal decision on whether to initiate CAR-T ther- apy should hinge on multidisciplinary team evaluation and be tai- lored to each patient on a case-by-case basis. Patients with lower dose of immunosuppressive treatment and without recent history of graft rejection are probably the best candidates.