Dual anti-CD19/22 and anti-BCMA CAR T-cell therapy in a patient with multiple myeloma and secondary B-ALL Open Access

TO THE EDITOR:

Secondary malignancies occur in ∼5% of patients with multiple myeloma (MM).^1,2 Management is often challenged by organ toxicity from previous therapies such as limited hematopoietic reserve or concomitant progression of MM. Chimeric antigen receptor (CAR) T cells offer a highly efficacious treatment of short duration involving limited chemotherapy and can thus be offered to patients ineligible for long-term intensive therapy regimens.^3,4 Here, we report the case of a patient with MM who was concomitantly diagnosed with secondary B-cell acute lymphoblastic leukemia (B-ALL) and MM progression. She received 2 distinct CAR T-cell products against B-cell maturation antigen (BCMA) and CD19/CD22, respectively, and achieved durable remission of both diseases. To our knowledge, such cotreatments have not yet been reported, and it is important to explore the safety and efficacy of this approach.

A 60-year-old female patient presented to our hospital with a soft tissue infection and a painless mass in the right clavicle. Five years prior, she was diagnosed with MM (immunoglobulin G κ, no International Myeloma Working Group high-risk cytogenetic aberrations⁵) and had received induction therapy (bortezomib-lenalidomide-dexamethasone) followed by high-dose melphalan, autologous hematopoietic stem cell transplantation, and lenalidomide maintenance. At presentation, laboratory workup revealed pancytopenia, increased inflammatory markers, and elevated paraprotein levels. Myeloma progression was confirmed using computed tomography, which revealed new osteolytic lesions and a large mass on the right clavicle. This was later histologically confirmed as a paramedullary MM manifestation. Intriguingly, 32% blasts were detectable in the peripheral blood (PB), and a bone marrow (BM) biopsy revealed infiltration with 82% pro–B-ALL blasts with normal karyotype and absence of BCR::ABL, next to 5% plasma cells, leading to the diagnosis of secondary pro–B-cell ALL.

The patient showed an Eastern Cooperative Oncology Group performance score of 1, and ALL treatment was initiated according to the German Multicenter Study Group on Adult Acute Lymphoblastic Leukemia recommendations for patients aged >55 years.⁶ As the regimen included several agents with potency against MM, no concomitant MM-specific treatment was initiated at the time. Radiation therapy of the para-medullary lesion was omitted based on patient preferences. During the first induction cycle, the patient experienced a progressive pulmonary fungal infection, with the detection of Aspergillus antigen in the serum, and febrile neutropenia owing to Bacteroides fragilis bacteremia. She furthermore complained of lower abdominal pain. Computed tomography of the abdomen revealed sigma diverticulitis, with development of a colovaginal fistula that was later confirmed using colposcopy. Given these complications, the patient was considered ineligible for further intensive chemotherapy. At this time point, a first disease assessment showed (minimal residual disease [MRD] positive) remission of the ALL but at the same time progression of MM, with 69% plasma cells in the BM.

The case was discussed in our cell therapy board, and CAR T-cell therapy targeting both MM and ALL was viewed as the most promising approach to achieve long-term remission of both diseases, with a moderate risk for further prolonged neutropenia. Ciltacabtagene autoleucel (Cilta-Cel) was recommended as an approved drug for relapsed MM,⁷ and in-house manufactured anti-CD19/22 CAR T cells were submitted for application based on a hospital exemption for advanced therapy medicinal product treatment. B-ALL blasts showed robust expression of CD19 and CD22 but were BCMA⁻. MM cells were BCMA⁺, showed minimal expression of CD19, and were CD22⁻. After leukapheresis for Cilta-Cel production, the patient received a bridging therapy with carfilzomib and dexamethasone for MM. At detection of a molecular ALL relapse, one additional cycle of high-dose cytarabine (1000 mg/m²; days 1-3) was applied. Then, the second leukapheresis was performed, and in-house CD19/22 CAR T cells were manufactured as previously described,^8,9 using an anti-CD19/CD22 lentiviral construct (kindly provided by Miltenyi Biotec) and a 12-day expansion in the CliniMACS Prodigy system in our academic Good Manufacturing Practice facility. CAR T cells were applied after a single lymphodepleting chemotherapy (fludarabine, 30 mg/m²; cyclophosphamide, 300 mg/m²; day –5 to day –3) with fresh anti-CD19/22 CAR T cells administered first (3.2 × 10⁶/kg body weight; day 0) and cryopreserved Cilta-Cel infused 24 hours later (0.6 × 10⁶/kg body weight; day +1). With the aim of avoiding potential early-onset toxicities and interactions between CAR T-cell products, these were administered sequentially on consecutive days (Figure 1A). Anticipating early expansion as well as for logistical reasons, we opted to infuse the noncryopreserved anti-CD19/22 CAR T cells first.

Twenty-four hours after the second CAR T-cell infusion (day +2), the patient developed a severe hyperinflammatory syndrome, with cytokine release syndrome characterized by fever and hypotension (American Society for Transplantation and Cellular Therapy [ASTCT] grade 3¹⁰), and an immune effector cell–associated neurotoxicity syndrome (ASTCT grade 1¹⁰) with mild cognitive impairment. Laboratory assessment showed cytopenia and marked hyperinflammation with elevated ferritin and soluble interleukin-2 receptor levels (Figure 1B-E), indicating an immune effector cell–associated hemophagocytic lymphohistiocytosis–like syndrome. The patient received 4 doses of tocilizumab (8 mg/kg body weight), dexamethasone (10 mg every 4 days, starting day +6), Anakinra (from day +7 to day +17; Figure 1A), and granulocyte colony-stimulating factor owing to cytopenia and diagnosis of early immune effector cell–associated hematotoxicity (Figure 1E). The patient’s condition continuously improved under this treatment, and she was discharged from the hospital on day +15 for further monitoring in an outpatient setting.

Flow cytometry–based immunomonitoring¹¹ showed early and marked expansion of CD19/22 CAR T cells coinciding with the hyperinflammatory adverse events, whereas Cilta-Cel levels peaked at low cell numbers (Figure 1F). Longitudinal phenotyping (Figure 1G-H) showed highly activated CAR T-cell populations at early time points and a transition toward a central memory phenotype at later time points. Subpopulations of both CAR T-cell products retained an activated phenotype on day +135. In line with sustained CAR T-cell activity, PB immunophenotyping showed sustained complete B-cell depletion (Figure 1J).

At the time of CAR T-cell infusion, the patient had shown progressive MM (increase in paraprotein) as well as ALL (increase in MRD level), despite bridging therapies (Figure 1I-J). At the first response assessment after CAR T-cell therapy (7 weeks after infusion), BM cytology and histology showed a complete remission of both diseases. Immunoglobulin H rearrangement–based MRD assessment of ALL (sensitivity of 10^–5) was negative and MM serum marker assessment demonstrated a very good partial remission.¹² At the latest follow-up ∼7 months after CAR T-cell therapy, ongoing MRD-negative remission of ALL was confirmed, and a complete remission of MM in serum and BM was noted. Magnetic resonance imaging revealed regression of the right clavicle mass (Figure 1K) and stable bone lesions.

To our knowledge, this is the first report of successful CAR T-cell cotreatment for 2 hematologic cancers. The treatment was accompanied by severe hyperinflammation, warranting extensive immunosuppressive treatment. The safety of in-house CD19/22 CAR T cells will be assessed in an upcoming phase 1 study for the treatment of B-cell malignancies.¹³ Downsizing of individual CAR T-cell dosages might allow to reduce the severity of adverse events induced by the higher cumulative CAR T-cell number. However, treatment toxicity can be influenced by multiple clinical variables, including response to bridging therapy.^14-16 BCMA and CD19/CD22 CAR T cells persisted side by side in the PB of the patient, with the fresh CD19/CD22 CAR T-cell product infused first expanded to a greater extent. A competitive advantage for space and homeostatic cytokines may have contributed to the observed expansion kinetics.

Our case highlights the feasibility of cotreatment with 2 distinct CAR T-cell products, indicating that each can be effective but increased toxicity and competition may occur. Although secondary lymphoid malignancies are rare in patients with MM,^17,18 our approach provides valuable insights into combined cellular therapies beyond the unique constellation treated in our patient. Additional studies are necessary to define ideal administration regimens. Using distinct CAR T-cell products to target several antigens may also be useful in a single disease setting to enhance therapeutic efficacy by reducing the risk of antigen escape.

Acknowledgments: The authors thank the personnel involved in the treatment of the patient and those involved in the manufacturing process of CD19/22 CAR T cells, especially Peter Lang, Christian Seitz, Daniel Atar, Christiane Braun, Marina Schmidt, and Katrin Lutz. The authors are grateful to the team of leukapheresis and flow cytometry units. The authors thank Miltenyi Biotec for supplying CAR vectors.

The project was supported, in part, by funding from the Deutsche Forschungsgemeinschaft (DFG; German Research Foundation; grants 467578951 and 46757750 [C.L. and W.B.]) and Medical Innovation through Interdisciplinarity (MINT)-Clinician Scientist program (DFG grant 493665037 [M.R.]).

Contribution: M.R., L.Hensen., F.G., C.F., C.L., and W.B. designed the research and performed the treatment; W.B. supervised the CAR T-cell production; F.S. performed flow cytometry analysis; M.R., W.B., and C.L. drafted the manuscript; and all authors edited the manuscript.

Conflict-of-interest disclosure: The authors declare no competing financial interests.

Correspondence: Wolfgang Bethge, Department of Hematology, Oncology, Clinical Immunology, and Rheumatology, University Hospital Tübingen, Otfried-Müller-Str 10, 72076 Tübingen, Germany; email: wolfgang.bethge@med.uni-tuebingen.de.