CAR T-cells and macrophages in large B-cell lymphoma: impact on toxicity and efficacy

Chimeric antigen receptor (CAR) T-cell therapy targeting CD19 is the current standard of care for the treatment of relapsed refractory large B cell lymphoma, demonstrating impressive response rates in the second- and third-line setting. Despite these advances, this treatment strategy can result in significant toxicities, such as cytokine release syndrome or immune effector cell associated neurotoxicity syndrome. While the exact mechanisms of these immune-mediated toxicities are not clearly understood, emerging pre-clinical and clinical studies have revealed the pivotal role of myeloid cells, particularly macrophages, as key contributors to the efficacy of treatments and as crucial mediators of toxicity. In this review, we discuss the current understanding of how macrophages mediate these effects, highlighting specific mechanisms of macrophage biology relevant to CAR T-cell therapy activity and side effects. These findings are resulting in novel treatment strategies that target macrophages, and able to mitigate toxicity while preserving CAR T-cell therapy efficacy.

Immune-based therapies in diffuse large B-cell lymphoma

INTRODUCTION

Diffuse large B-cell lymphoma (DLBCL) is an aggressive and clinically heterogeneous malignancy originating from B-cells with up to 40% of patients experiencing primary refractory disease or relapse after first-line treatment. However, the past 5 years have seen a flurry of new drug approvals for DLBCL anchored upon new immune therapies, including chimeric antigen receptor (CAR) T-cells and antibody-based therapies.

AREAS COVERED

This article summarizes recent advances in the treatment of DLBCL, including in the first line and relapsed and refractory setting (second-line and beyond). A literature search was conducted for publications relevant to the immunotherapeutic approach to DLBCL from 2000 through March 2023 within PubMed and articles were reviewed. The search terms were immunotherapy, monoclonal antibodies, chimeric antigen receptor modified T-cell (CAR-T), and classification of DLBCL. Relevant clinical trials and pre-clinical studies exploring the strengths and weaknesses of current immune therapies against DLBCL were chosen. We additionally explored how intrinsic differences amongst DLBCL subtype biology and endogenous host immune recruitment contribute to variable therapeutic efficacy.

EXPERT OPINION

Future treatments will minimize chemotherapy exposure and be chosen by underlying tumor biology, paving the way for the promise of chemotherapeutic free regimens and improved outcomes for poor-risk subgroups.

Neoadjuvant Pembrolizumab and High-Dose IFNα-2b in Resectable Regionally Advanced Melanoma

PURPOSE

Neoadjuvant immunotherapy may improve the clinical outcome of regionally advanced operable melanoma and allows for rapid clinical and pathologic assessment of response. We examined neoadjuvant pembrolizumab and high-dose IFNα-2b (HDI) therapy in patients with resectable advanced melanoma.

PATIENTS AND METHODS

Patients with resectable stage III/IV melanoma were treated with concurrent pembrolizumab 200 mg i.v. every 3 weeks and HDI 20 MU/m²/day i.v., 5 days per week for 4 weeks, then 10 MU/m²/day subcutaneously 3 days per week for 2 weeks. Definitive surgery followed, as did adjuvant combination immunotherapy, completing a year of treatment. Primary endpoint was safety of the combination. Secondary endpoints included overall response rate (ORR), pathologic complete response (pCR), recurrence-free survival (RFS), and overall survival (OS). Blood samples for correlative studies were collected throughout. Tumor tissue was assessed by IHC and flow cytometry at baseline and at surgery.

RESULTS

A total of 31 patients were enrolled, and 30 were evaluable. At data cutoff (October 2, 2019), median follow-up for OS was 37.87 months (range, 33.2-43.47). Median OS and RFS were not reached. Radiographic ORR was 73.3% [95% confidence interval (CI): 55.5-85.8], with a 43% (95% CI: 27.3-60.1) pCR rate. None of the patients with a pCR have had a recurrence. HDI and pembrolizumab were discontinued in 73% and 43% of patients, respectively. Correlative analyses suggested that intratumoral PD-1/PD-L1 interaction and HLA-DR expression are associated with pCR (P = 0.002 and P = 0.008, respectively).

CONCLUSIONS

Neoadjuvant concurrent HDI and pembrolizumab demonstrated promising clinical activity despite high rates of treatment discontinuation. pCR is a prognostic indicator.See related commentary by Menzies et al., p. 4133.

Severe anaplasmosis represents a treatable cause of secondary hemophagocytic lymphohistiocytosis: Two cases and review of literature

Anaplasmosis is an emerging infection in the United States and remains under-recognized in many areas including Pennsylvania. Presenting signs and symptoms are often nonspecific, but fulminant infection can occur in vulnerable populations. We present two cases of severe anaplasmosis that progressed to secondary hemophagocytic lymphohistiocytosis (HLH). This severe immune dysregulation syndrome has an extremely high mortality, but anaplasmosis represents one of the few treatable underlying etiologies. It is imperative for physicians to recognize this complication and start empiric doxycycline, as early treatment improves mortality. We also present a case of anaplasmosis-induced HLH successfully treated with a combination of doxycycline, steroids, and anakinra (an IL-1 receptor antagonist), highlighting that this primarily immune-mediated complication is amenable to treatment with both antibiotics and immune suppression.

A phase I study of neoadjuvant combination immunotherapy in locally/regionally advanced melanoma

9586

Background: A trial of neoadjuvant pembrolizumab (P) in combination with high dose interferon-α (HDI) in high-risk patients (pts) with locoregionally advanced melanoma (mel) has completed enrollment. Methods: Primary endpoint: safety of combination P-HDI. Pts were treated with P x 2 doses followed by definitive surgery, then x1 year. HDI was given concurrently, and both agents were per standard regimen. Tumor and blood samples were obtained at baseline and at surgery (wk 6-8), blood at 6 wks, 3,6,12 months (mos). Results: 30 pts were treated (22 male, 8 female, age 26-83). 16 had cutaneous primary, 3 mucosal, 11 unknown. At enrollment, 16 had recurrent disease, 6 received prior adjuvant therapy with ipilimumab (4) or HDI (2). 16 had AJCC 7 stage IIIB, 9 IIIC, 5 IV. 332 P cycles have been delivered (median 13), 496 doses of HDI induction (median 17), 1329 doses of HDI maintenance (median 44). HDI was dose reduced in 20 pts, discontinued in 27, P discontinued in 8. Radiologic preoperative RR was 77% (95% CI, 59-88) (6 CR, 17 PR). 20% (6) had SD and 1 had PD. All pts underwent definitive surgery. The pathologic complete response (pCR) of 26 pts was 32% (95% CI, 18-51). 6 pts recurred and 3 died. No pt with pCR has recurred. Median f/u time is 17.4 mos, median PFS/OS not reached. Most common grade (Gr) 3 toxicities: hypophosphatemia (10; 33%), fatigue (10; 33%), ↑CPK (6; 20%), ↑lipase (4; 13%). 3 Gr 4 events (↑CPK, hyperglycemia, lymphocyte count decreased). 1 suspected grade 5 event occurred 6 months after completion of therapy. PD-L1 expression at baseline did not correlate with clinical outcomes. In 8 pts with pre and post treatment tumor samples, IHC expression of PD-1, PD-L1, CD11b, CD8, Foxp3 and CD25 increased post-treatment (p < 0.05). Conclusions: Neoadjuvant P-HDI has promising clinical activity, although treatment is limited by HDI toxicity. Treatment increases the immune cell infiltrate, and outcomes do not correlate with baseline expression of PD-L1. Longer follow up and further mechanistic studies are underway. Clinical trial information: NCT02339324.

Culture conditions promoting innate immunity and homeostatic proliferation generate highly enriched, MUC1- or HER2/neu-specific CD4+ and CD8+ T cells (P4419)

Although tumors from melanoma patients can often provide a source of therapeutically active T cells for adoptive therapy, it has historically proved challenging to employ peripheral blood as the T cell source for any type of cancer. We have observed nonetheless that HER2-specific T cells can be Ag-driven and enriched in culture when PBMCs from HER2-vaccinated breast cancer patients are treated with exogenous IL12. We hypothesized that stimulating innate immunity could further improve PBMC cultures by activating the DC subpopulation more effectively than adding exogenous rIL12. Bulk PBMC exposure to optimized TLR agonists produced vast quantities of IL12 and IL23, and upregulated HLA-DR, B7.1 and CD40 in the DC subpopulation, effects not produced by exogenous IL12. Subsequent IL7 exposure emulated homeostatic proliferation, selectively causing the Ag-driven T cell subset both to proliferate faster and to strongly resist apoptosis. Ag-specificity within two weeks approached 80-100% of both CD4+ and CD8+ T cells for recall Ags and 1-15% for a wide array of MUC1- and HER2-derived peptides, including the ability to distinguish glycoforms. Culture-expanded T cells retained a young CD28+/CD56- phenotype, uniformly expressed ROR-γ during culture, variably produced IL-2 and/or IL-17, and uniformly expressed T-bet and secreted IFN-γ when reexposed to Ag. Such T1/T17 bipotency may be ideal for anti-tumor adoptive therapy and highly efficient for use in Ag discovery.

A therapeutic OX40 agonist dynamically alters dendritic, endothelial, and T cell subsets within the established tumor microenvironment

Little preclinical modeling currently exists to support the use of OX40 agonists as therapeutic agents in the setting of advanced cancers, as well as the mechanisms through which therapeutic efficacy is achieved. We show that treatment of mice bearing well-established day 17 sarcomas with a novel OX40 ligand-Fc fusion protein (OX40L-Fc) resulted in tumor regression or dormancy in the majority of treated animals. Unexpectedly, dendritic cells (DC) in the progressive tumor microenvironment (TME) acquire OX40 expression and bind fluorescently labeled OX40L-Fc. Furthermore, longitudinal analyses revealed that DCs become enriched in the tumor-draining lymph node (TDLN) of both wild-type and Rag-/- mice within 3 days after OX40L-Fc treatment. By day 7 after treatment, a significant expansion of CXCR3+ T effector cells was noted in the TDLN, and by day 10 after treatment, type 1 polarized T cells exhibiting a reactivated memory phenotype had accumulated in the tumors. High levels of CXCL9 (a CXCR3 ligand) and enhanced expression of VCAM-1 by vascular endothelial cells (VEC) were observed in the TME early after treatment with OX40L-Fc. Notably, these vascular alterations were maintained in Rag-/- mice, indicating that the OX40L-Fc-mediated activation of both DC and VEC occurs in a T-cell-independent manner. Collectively, these findings support a paradigm in which the stimulation of DC, T cells, and the tumor vasculature by an OX40 agonist dynamically orchestrates the activation, expansion, and recruitment of therapeutic T cells into established tumors.

Hormonal and growth factor responses to heavy resistance exercise protocols

To examine endogenous anabolic hormone and growth factor responses to various heavy resistance exercise protocols (HREPs), nine male subjects performed each of six randomly assigned HREPs, which consisted of identically ordered exercises carefully designed to control for load [5 vs. 10 repetitions maximum (RM)], rest period length (1 vs. 3 min), and total work effects. Serum human growth hormone (hGH), testosterone (T), somatomedin-C (SM-C), glucose, and whole blood lactate (HLa) concentrations were determined preexercise, midexercise (i.e., after 4 of 8 exercises), and at 0, 5, 15, 30, 60, 90, and 120 min postexercise. All HREPs produced significant (P less than 0.05) temporal increases in serum T concentrations, although the magnitude and time point of occurrence above resting values varied across HREPs. No differences were observed for T when integrated areas under the curve (AUCs) were compared. Although not all HREPs produced increases in serum hGH, the highest responses were observed consequent to the H10/1 exercise protocol (high total work, 1 min rest, 10-RM load) for both temporal and time integrated (AUC) responses. The pattern of SM-C increases varied among HREPs and did not consistently follow hGH changes. Whereas temporal changes were observed, no integrated time (AUC) differences between exercise protocols occurred. These data indicate that the release patterns (temporal or time integrated) observed are complex functions of the type of HREPs utilized and the physiological mechanisms involved with determining peripheral circulatory concentrations (e.g., clearance rates, transport, receptor binding). All HREPs may not affect muscle and connective tissue growth in the same manner because of possible differences in hormonal and growth factor release.