CD19 occupancy with tafasitamab increases therapeutic index of CART19 cell therapy and diminishes severity of CRS.

ABSTRACT: In the development of various strategies of anti-CD19 immunotherapy for the treatment of B-cell malignancies, it remains unclear whether CD19 monoclonal antibody therapy impairs subsequent CD19-targeted chimeric antigen receptor T-cell (CART19) therapy. We evaluated the potential interference between the CD19-targeting monoclonal antibody tafasitamab and CART19 treatment in preclinical models. Concomitant treatment with tafasitamab and CART19 showed major CD19 binding competition, which led to CART19 functional impairment. However, when CD19+ cell lines were pretreated with tafasitamab overnight and the unbound antibody was subsequently removed from the culture, CART19 function was not affected. In preclinical in vivo models, tafasitamab pretreatment demonstrated reduced incidence and severity of cytokine release syndrome and exhibited superior antitumor effects and overall survival compared with CART19 alone. This was associated with transient CD19 occupancy with tafasitamab, which in turn resulted in the inhibition of CART19 overactivation, leading to diminished CAR T apoptosis and pyroptosis of tumor cells.

Targeting cancer-associated fibroblasts in the bone marrow prevents resistance to CART-cell therapy in multiple myeloma.

Pivotal clinical trials of B-cell maturation antigen-targeted chimeric antigen receptor T (CART)-cell therapy in patients with relapsed/refractory multiple myeloma (MM) resulted in remarkable initial responses, which led to a recent US Food and Drug Administration approval. Despite the success of this therapy, durable remissions continue to be low, and the predominant mechanism of resistance is loss of CART cells and inhibition by the tumor microenvironment (TME). MM is characterized by an immunosuppressive TME with an abundance of cancer-associated fibroblasts (CAFs). Using MM models, we studied the impact of CAFs on CART-cell efficacy and developed strategies to overcome CART-cell inhibition. We showed that CAFs inhibit CART-cell antitumor activity and promote MM progression. CAFs express molecules such as fibroblast activation protein and signaling lymphocyte activation molecule family-7, which are attractive immunotherapy targets. To overcome CAF-induced CART-cell inhibition, CART cells were generated targeting both MM cells and CAFs. This dual-targeting CART-cell strategy significantly improved the effector functions of CART cells. We show for the first time that dual targeting of both malignant plasma cells and the CAFs within the TME is a novel strategy to overcome resistance to CART-cell therapy in MM.

Factors associated with outcomes after a second CD19-targeted CAR T-cell infusion for refractory B-cell malignancies.

CD19-targeted chimeric antigen receptor-engineered (CD19 CAR) T-cell therapy has shown significant efficacy for relapsed or refractory (R/R) B-cell malignancies. Yet, CD19 CAR T cells fail to induce durable responses in most patients. Second infusions of CD19 CAR T cells (CART2) have been considered as a possible approach to improve outcomes. We analyzed data from 44 patients with R/R B-cell malignancies (acute lymphoblastic leukemia [ALL], n = 14; chronic lymphocytic leukemia [CLL], n = 9; non-Hodgkin lymphoma [NHL], n = 21) who received CART2 on a phase 1/2 trial (NCT01865617) at our institution. Despite a CART2 dose increase in 82% of patients, we observed a low incidence of severe toxicity after CART2 (grade ≥3 cytokine release syndrome, 9%; grade ≥3 neurotoxicity, 11%). After CART2, complete response (CR) was achieved in 22% of CLL, 19% of NHL, and 21% of ALL patients. The median durations of response after CART2 in CLL, NHL, and ALL patients were 33, 6, and 4 months, respectively. Addition of fludarabine to cyclophosphamide-based lymphodepletion before the first CAR T-cell infusion (CART1) and an increase in the CART2 dose compared with CART1 were independently associated with higher overall response rates and longer progression-free survival after CART2. We observed durable CAR T-cell persistence after CART2 in patients who received cyclophosphamide and fludarabine (Cy-Flu) lymphodepletion before CART1 and a higher CART2 compared with CART1 cell dose. The identification of 2 modifiable pretreatment factors independently associated with better outcomes after CART2 suggests strategies to improve in vivo CAR T-cell kinetics and responses after repeat CAR T-cell infusions, and has implications for the design of trials of novel CAR T-cell products after failure of prior CAR T-cell immunotherapies.

Leukemic extracellular vesicles induce chimeric antigen receptor T cell dysfunction in chronic lymphocytic leukemia.

Chimeric antigen receptor (CAR) T cell therapy has yielded unprecedented outcomes in some patients with hematological malignancies; however, inhibition by the tumor microenvironment has prevented the broader success of CART cell therapy. We used chronic lymphocytic leukemia (CLL) as a model to investigate the interactions between the tumor microenvironment and CART cells. CLL is characterized by an immunosuppressive microenvironment, an abundance of systemic extracellular vesicles (EVs), and a relatively lower durable response rate to CART cell therapy. In this study, we characterized plasma EVs from untreated CLL patients and identified their leukemic cell origin. CLL-derived EVs were able to induce a state of CART cell dysfunction characterized by phenotypical, functional, and transcriptional changes of exhaustion. We demonstrate that, specifically, PD-L1+ CLL-derived EVs induce CART cell exhaustion. In conclusion, we identify an important mechanism of CART cell exhaustion induced by EVs from CLL patients.

Late Events after Treatment with CD19-Targeted Chimeric Antigen Receptor Modified T Cells.

CD19-targeted chimeric antigen receptor-modified T cell (CAR-T cell) therapy has shown excellent antitumor activity in patients with relapsed/refractory B cell malignancies, with very encouraging response rates and outcomes. However, the late effects following this therapy remain unknown. Here we report late adverse events-defined as starting or persisting beyond 90 days after CAR-T cell infusion-in patients who survived at least 1 year after therapy. The median duration of follow-up was 28.1 months (range, 12.5 to 62.6 months). At last follow-up, 73% of patients were still alive and 24% were in ongoing complete remission (CR). The most common late adverse event was hypogammaglobulinemia (IgG <400 mg/dL or i.v immunoglobulinm (IVIG) replacement, observed in 67% of the patients with available data. Infection density was .55 infection/100 days at risk (2.08 per patient-year). The majority (80%) of the infections were treated in the outpatient setting, and 5% necessitated admission to the intensive care unit (ICU). Subsequent malignancies occurred in 15% of patients, including 5% with myelodysplastic syndrome (MDS). Among patients with ongoing CR and with no MDS, 16% experienced prolonged cytopenia requiring transfusions or growth factor support. Graft-versus-host disease occurred in 3 of 15 patients (20%) who had undergone previous allogeneic hematopoietic cell transplantation. Most of the late events observed in this cohort were not severe, and many could be related to previous or subsequent therapies, suggesting a safe long-term profile of CD19-targeted CAR-T cell immunotherapy.

Patient-Reported Neuropsychiatric Outcomes of Long-Term Survivors after Chimeric Antigen Receptor T Cell Therapy.

CD19-targeted chimeric antigen receptor (CAR) modified T cell immunotherapy is a novel treatment with promising results in patients with relapsed/refractory lymphoid malignancies. CAR T cell therapy has known early toxicities of cytokine release syndrome and neurotoxicity, but little is known about long-term neuropsychiatric adverse effects. We have used patient-reported outcomes, including Patient-Reported Outcomes Measurement Information System (PROMIS) measures, to assess neuropsychiatric and other patient-reported outcomes of 40 patients with relapse/refractory chronic lymphocytic leukemia, non-Hodgkin lymphoma, and acute lymphoblastic leukemia 1 to 5 years after treatment with CD19-targeted CAR T cells. Mean T scores of PROMIS domains of global mental health, global physical health, social function, anxiety, depression, fatigue, pain, and sleep disturbance were not clinically meaningfully different from the mean in the general US population. However, 19 patients (47.5%) reported at least 1 cognitive difficulty and/or clinically meaningful depression and/or anxiety, and 7 patients (17.5%) scored ≤40 in global mental health, indicating at least 1 standard deviation worse than the general population mean. Younger age was associated with worse long-term global mental health (P = .02), anxiety (P = .001), and depression (P= .01). Anxiety before CAR T cell therapy was associated with increased likelihood of anxiety after CAR T cell therapy (P = .001). Fifteen patients (37.5%) reported cognitive difficulties after CAR T cell therapy. Depression before CAR T cell therapy was statistically significantly associated with higher likelihood of self-reported post-CAR T cognitive difficulties (P = .02), and there was a trend for an association between acute neurotoxicity and self-reported post-CAR T cognitive difficulties (P = .08). Having more post-CAR T cognitive difficulties was associated with worse global mental health and global physical health. Our study demonstrates overall good neuropsychiatric outcomes in 40 long-term survivors after CAR T cell therapy. However, nearly 50% of patients in the cohort reported at least 1 clinically meaningful negative neuropsychiatric outcome (anxiety, depression, or cognitive difficulty), indicating that a significant number of patients would likely benefit from mental health services following CAR T cell therapy. Younger age, pre-CAR T anxiety or depression, and acute neurotoxicity may be risk factors for long-term neuropsychiatric problems in this patient population. Larger studies are needed to confirm these findings.

Rhizopus arrhizus and Fusarium solani Concomitant Infection in an Immunocompromised Host.

Neutropenic patients are at risk of the development of hyalohyphomycosis and mucormycosis. Correct identification is essential for the initiation of the specific treatment, but concomitant mold infections are rarely reported. We report one unprecedented case of concomitant mucormycosis and fusariosis in a neutropenic patient with acute myeloid leukemia. The patient developed rhino-orbital infection by Rhizopus arrhizus and disseminated infection by Fusarium solani. The first culture from a sinus biopsy grew Rhizopus, which was consistent with the histopathology report of mucormycosis. A second sinus biopsy collected later during the patient's clinical deterioration was reported as hyalohyphomycosis, and the culture yielded F. solani. Due to the discordant reports, the second biopsy was reviewed and two hyphae types suggestive of both hyalohyphomycetes and mucormycetes were found. The dual mold infection was confirmed by PCR assays from paraffinized tissue sections. Increased awareness of the existence of dual mold infections in at-risk patients is necessary. PCR methods in tissue sections may increase the diagnosis of dual mold infections. In case of sequential biopsies showing discrepant results, mixed infections have to be suspected.

SOHO State of the Art Updates and Next Questions Updates on Building Your CAR-T Cell Program.

Chimeric antigen receptor T-cell (CAR-T) therapy has significantly impacted treatment algorithms and clinical outcomes for a variety of patients with hematologic malignancies over the past decade. The field of cellular immunotherapy is currently experiencing a rapid expansion of the number of patients eligible for CAR-T therapies as approvals are being seen in earlier lines of therapy. With the expanded patients eligible for these therapies, more treatment centers will be necessary to keep up with demand. Building a cellular therapy program can be a daunting task, and therefore, we present our experience with building a clinical cellular therapy program.

Late events after anti-CD19 CAR T-cell therapy for relapsed/refractory B-cell non-Hodgkin lymphoma.

Background: The short-term complications from chimeric antigen receptor T-cell therapy (CART) are well characterized, but the long-term complications still need to be further investigated. Therefore, herein, we will review the currently available literature published on the late adverse events following CART. Methods: We reviewed published data available from pivotal trials and real-world experiences with anti-CD19 CART (CART19) for adults with lymphoma. We defined late events as occurring or persisting beyond 1 month after CART infusion. We focused our literature review on the following late-event outcomes post-CART19: cytopenia, immune reconstitution, infections, and subsequent malignancies. Results: Grade 3-4 cytopenia beyond 30 days occurs in 30%-40% of patients and beyond 90 days in 3%-22% of patients and is usually managed with growth-factor and transfusion support, along with neutropenic prophylaxis. B-cell aplasia and hypogammaglobulinemia are expected on-target off-tumor effects of CART19, 44%-53% of patients have IgG < 400 mg/dL, and approximately 27%-38% of patients receive intravenous immunoglobulin (IVIG) replacement. Infections beyond the initial month from CART19 are not frequent and rarely severe, but they are more prevalent and severe when patients receive subsequent therapies post-CART19 for their underlying disease. Late neurotoxicity and neurocognitive impairment are uncommon, and other causes should be considered. T-cell lymphoma (TCL) after CART is an extremely rare event and not necessarily related to CAR transgene. Myeloid neoplasm is not rare post-CART, but unclear causality given heavily pretreated patient population is already at risk for therapy-related myeloid neoplasm. Conclusion: CART19 is associated with clinically significant long-term effects such as prolonged cytopenia, hypogammaglobulinemia, and infections that warrant clinical surveillance, but they are mostly manageable with a low risk of non-relapse mortality. The risk of subsequent malignancies post-CART19 seems low, and the relationship with CART19 and/or prior therapies is unclear; but regardless of the possible causality, this should not impact the current benefit-risk ratio of CART19 for relapsed/refractory B-cell non-Hodgkin lymphoma (NHL).

Combination ruxolitinib and belumosudil is tolerable and induces responses despite treatment failure as monotherapies.

FDA approved agents for the treatment of chronic GVHD including ruxolitinib and belumosudil are effective steroid-sparing agents, with overall response rates (ORR) of 76% and 65% respectively. Ruxolitinib and belumosudil are well tolerated with different primary targets. Little data is available on the use of combination ruxolitinib and belumosudil. This is a single center, retrospective analysis of 20 treatment-refractory patients with chronic GVHD treated with combination ruxolitinib and belumosudil. The ORR including complete response (CR) and partial response (PR) at any time was 55% (11/20). Among responding patients, other immunosuppressive agents were tapered or discontinued in all patients. None of the patients developed EBV or CMV reactivation requiring treatment. 4 patients (20%) developed pneumonia and 2 patients (10%) developed viral URI. Cytopenias were not exacerbated. No patients had graft failure or relapsed disease. The combination is tolerable, delays the need for alternative therapies, and facilitates tapering of corticosteroids.

Siltuximab for Chimeric Antigen Receptor T-Cell Therapy Related CRS and ICANS - A Multicenter Retrospective Analysis.

Chimeric Antigen Receptor T-Cell therapies (CAR-T) are effective in many hematologic malignancies; however, adverse events including cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) can affect a significant number of patients. Those who develop refractory CRS or ICANS have few treatment options. Siltuximab, a monoclonal antibody binding circulating IL-6, has been proposed to have clinical activity in both CRS and ICANS. We conducted a multi-center retrospective analysis of siltuximab treatment for CRS and ICANS following CAR-T cell therapy in a real-world cohort from six academic centers. Fifty-four patients were evaluated. Sixteen patients had CRS previously treated with tocilizumab and 17 patients had ICANS previously treated with steroids. Of the all the patients with CRS at the time of siltuximab, 75% had improvement in CRS grade. Of the all the patients with ICANS at the time of siltuximab, 60% had improvement in ICANS grade. To our knowledge, this is the largest cohort of patients treated with siltuximab for CRS and/or ICANS following CAR-T. Siltuximab appeared to be effective for both CRS and ICANS, including previously treated toxicities. These data support the use of siltuximab in CRS and ICANS as well as provide rationale for future prospective studies.

Postinfusion PD-1+ CD8+ CAR T cells identify patients responsive to CD19 CAR T-cell therapy in non-Hodgkin lymphoma.

ABSTRACT: Chimeric antigen receptor (CAR) T-cell therapy has revolutionized treatment for relapsed/refractory B-cell non-Hodgkin lymphoma (NHL). Robust biomarkers and a complete understanding of CAR T-cell function in the postinfusion phase remain limited. Here, we used a 37-color spectral flow cytometry panel to perform high dimensional single-cell analysis of postinfusion samples in 26 patients treated with CD28 costimulatory domain containing commercial CAR T cells for NHL and focused on computationally gated CD8+ CAR T cells. We found that the presence of postinfusion Programmed cell death protein 1 (PD-1)+ CD8+ CAR T cells at the day 14 time point highly correlated with the ability to achieve complete response (CR) by 6 months. Further analysis identified multiple subtypes of CD8+ PD-1+ CAR T cells, including PD-1+ T cell factor 1 (TCF1)+ stem-like CAR T cells and PD-1+ T-cell immunoglobulin and mucin-domain containing-3 (TIM3)+ effector-like CAR T cells that correlated with improved clinical outcomes such as response and progression-free survival. Additionally, we identified a subset of PD-1+ CD8+ CAR+ T cells with effector-like function that was increased in patients who achieved a CR and was associated with grade 3 or higher immune effector cell-associated neurotoxicity syndrome. Here, we identified robust biomarkers of response to CD28 CAR T cells and highlight the importance of PD-1 positivity in CD8+ CAR T cells after infusion in achieving CR.

Promises and challenges of a decentralized CAR T-cell manufacturing model.

Autologous chimeric antigen receptor-modified T-cell (CAR T) products have demonstrated un-precedent efficacy in treating many relapsed/refractory B-cell and plasma cell malignancies, leading to multiple commercial products now in routine clinical use. These positive responses to CAR T therapy have spurred biotech and big pharma companies to evaluate innovative production methods to increase patient access while maintaining adequate quality control and profitability. Autologous cellular therapies are, by definition, manufactured as single patient batches, and demand has soared for manufacturing facilities compliant with current Good Manufacturing Practice (cGMP) regulations. The use of a centralized production model is straining finite resources even in developed countries in North America and the European Union, and patient access is not feasible for most of the developing world. The idea of having a more uniform availability of these cell therapy products promoted the concept of point-of-care (POC) manufacturing or decentralized in-house production. While this strategy can potentially decrease the cost of manufacturing, the challenge comes in maintaining the same quality as currently available centrally manufactured products due to the lack of standardized manufacturing techniques amongst institutions. However, academic medical institutions and biotech companies alike have forged ahead innovating and adopting new technologies to launch clinical trials of CAR T products produced exclusively in-house. Here we discuss POC production of CAR T products.

Treatment strategies for relapse after CAR T-cell therapy in B cell lymphoma.

Clinical trials of anti-CD19 chimeric antigen receptor T (CART19) cell therapy have shown high overall response rates in patients with relapsed/refractory B-cell malignancies. CART19 cell therapy has been approved by the US Food and Drug Administration for patients who relapsed less than 12 months after initial therapy or who are refractory to first-line therapy. However, durable remission of CART19 cell therapy is still lacking, and 30%-60% of patients will eventually relapse after CART19 infusion. In general, the prognosis of patients who relapse after CART19 cell therapy is poor, and various strategies to treat this patient population have been investigated extensively. CART19 failures can be broadly categorized by the emergence of either CD19-positive or CD19-negative lymphoma cells. If CD19 expression is preserved on the lymphoma cells, a second infusion of CART19 cells or reactivation of previously infused CART19 cells with immune checkpoint inhibitors can be considered. When patients develop CD19-negative relapse, targeting different antigens (e.g., CD20 or CD22) with CAR T cells, investigational chemotherapies, or hematopoietic stem cell transplantation are potential treatment options. However, salvage therapies for relapsed large B-cell lymphoma after CART19 cell therapy have not been fully explored and are conducted based on clinicians' case-by-case decisions. In this review, we will focus on salvage therapies reported to date and discuss the management of relapsed/refractory large B-cell lymphomas after CART19 cell therapy.

Response to COVID-19 Vaccination Post-CAR T Therapy in Patients With Non-Hodgkin Lymphoma and Multiple Myeloma.

COVID-19 adversely affects individuals with cancer. Several studies have found that seroconversion rates among patients with hematologic malignancies are suboptimal when compared to patients without cancer. Patients with non-Hodgkin lymphoma (NHL) and multiple myeloma (MM) are immunocompromised due to impaired humoral and cellular immunity in addition to prescribed immunosuppressive therapy. Chimeric antigen receptor T-cell (CAR T) therapy is now widely used for NHL and MM, but little is known about seroconversion rates after COVID-19 vaccination among these populations. We evaluated SARS-CoV-2 spike-binding IgG antibody levels following COVID-19 vaccination among NHL and MM CAR T therapy recipients. Out of 104 CAR T infusions, 19 patients developed known COVID-19 infection post-CAR T. We tested 17 patients that received CAR T for antibody spike titers post COVID-19 vaccination, only 29 % (n = 5) were able to mount a clinically relevant antibody response (>250 IU/mL).

AXL Inhibition Improves the Antitumor Activity of Chimeric Antigen Receptor T Cells.

The receptor tyrosine kinase AXL is a member of the TYRO3, AXL, and proto-oncogene tyrosine-protein kinase MER family and plays pleiotropic roles in cancer progression. AXL is expressed in immunosuppressive cells, which contributes to decreased efficacy of immunotherapy. Therefore, we hypothesized that AXL inhibition could serve as a strategy to overcome resistance to chimeric antigen receptor T (CAR T)-cell therapy. To test this, we determined the impact of AXL inhibition on CD19-targeted CAR T (CART19)-cell functions. Our results demonstrate that T cells and CAR T cells express high levels of AXL. Specifically, higher levels of AXL on activated Th2 CAR T cells and M2-polarized macrophages were observed. AXL inhibition with small molecules or via genetic disruption in T cells demonstrated selective inhibition of Th2 CAR T cells, reduction of Th2 cytokines, reversal of CAR T-cell inhibition, and promotion of CAR T-cell effector functions. AXL inhibition is a novel strategy to enhance CAR T-cell functions through two independent, but complementary, mechanisms: targeting Th2 cells and reversing myeloid-induced CAR T-cell inhibition through selective targeting of M2-polarized macrophages.

GM-CSF disruption in CART cells modulates T cell activation and enhances CART cell anti-tumor activity.

Inhibitory myeloid cells and their cytokines play critical roles in limiting chimeric antigen receptor T (CART) cell therapy by contributing to the development of toxicities and resistance following infusion. We have previously shown that neutralization of granulocyte-macrophage colony-stimulating factor (GM-CSF) prevents these toxicities and enhances CART cell functions by inhibiting myeloid cell activation. In this report, we study the direct impact of GM-CSF disruption during the production of CD19-directed CART cells on their effector functions, independent of GM-CSF modulation of myeloid cells. In this study, we show that antigen-specific activation of GM-CSFKO CART19 cells consistently displayed reduced early activation, enhanced proliferation, and improved anti-tumor activity in a xenograft model for relapsed B cell malignancies. Activated CART19 cells significantly upregulate GM-CSF receptors. However, the interaction between GM-CSF and its upregulated receptors on CART cells was not the predominant mechanism of this activation phenotype. GM-CSFKO CART19 cell had reduced BH3 interacting-domain death agonist (Bid), suggesting an interaction between GM-CSF and intrinsic apoptosis pathways. In conclusion, our study demonstrates that CRISPR/Cas9-mediated GM-CSF knockout in CART cells directly ameliorates CART cell early activation and enhances anti-tumor activity in preclinical models.

An unusual case of aggressive malignant spread of epithelioid hemangioendothelioma.

Epithelioid hemangioendothelioma (EHE) is a rare vascular neoplasm which typically originates from liver, lung, or bone. Due to the low incidence of disease, the most effective treatment is not easily studied and much of the information known about EHE has been learned through case reports and case series. In this case, we will present an uncommon form of primary soft tissue EHE with local recurrence, bone metastasis, and lymphangitic spread to the lungs leading to respiratory failure. Imaging of the chest was atypical for EHE with intraseptal thickening and hilar lymphadenopathy. Respiratory failure was progressive despite aggressive multimodal treatment. This case highlights an unusually aggressive recurrence and metastasis of primary soft tissue EHE with atypical pulmonary imaging findings.