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Abstract CD19‐targeting treatments have shown promise in relapsed/refractory (R/R) diffuse large B‐cell lymphoma (DLBCL). Loncastuximab tesirine (loncastuximab tesirine‐lpyl [Lonca]) is a CD19‐targeting antibody‐drug conjugate indicated for R/R DLBCL after at least two systemic treatments. CD19 expression was evaluated in patients receiving Lonca in the LOTIS‐2 clinical trial with available tissue samples obtained after last systemic therapy/before Lonca treatment. Lonca cytotoxicity was evaluated in a panel of six lymphoma cell lines with various CD19 expression levels. Quantitative systems pharmacology (QSP) modelling was used to predict Lonca responses. Lonca responses were seen in patients across all CD19 expression levels, including patients with low/no detectable CD19 expression and H‐scores at baseline. Similarly, Lonca induced cytotoxicity in cell lines with different levels of CD19 expression, including one with very low expression. QSP modelling predicted that CD19 expression by immunohistochemistry alone does not predict Lonca response, whereas inclusion of CD19 surface density improved response prediction. Virtual patients responded to Lonca with estimated CD19 as low as 1000 molecules/cell of CD19, normally below the immunohistochemistry detection level. We found Lonca is an effective treatment for R/R DLBCL regardless of CD19 expression by immunohistochemistry. These results provide the basis for future studies addressing CD19‐targeted agent sequencing.

Patients with relapsed or refractory (R/R) diffuse large B-cell lymphoma (DLBCL) have a poor prognosis. Loncastuximab tesirine (Lonca), an antibody conjugate targeting CD19, has demonstrated significant clinical benefit in R/R DLBCL in a global phase 2 LOTIS-2 study. In the China bridging pivotal phase 2 OL-ADCT-402-001 study, eligible patients aged ≥18 years with R/R DLBCL who had failed ≥ 2 lines of systemic therapies were enrolled and treated with Lonca every 3 week with 150 μg/kg for 2 cycles; then 75 μg/kg for subsequent cycles (up to 1 year). The primary endpoint was overall response rate (ORR) assessed by independent review committee. Primary analyses for efficacy and safety were performed on the patients who received at least one treatment and had at least 6 months of follow-up following an initial documented response. As of data-cutoff, 64 patients received Lonca (median: 4.0 cycles [range: 1 to 17]). The median number of prior lines of therapies was 3.0 (range: 2 to 12). The ORR was 51.6% (95% CI: 38.7% to 64.2%), and the complete response rate was 23.4%. Hematological events accounted for the majority of the most common (≥15%) Grade ≥3 treatment-emergent adverse events (TEAEs), in which increased gamma glutamyltransferase (25.0%), and hypokalaemia (18.8%) also were reported. Serious TEAEs were reported in 35 of 64 patients with 4 fatal TEAEs. In conclusion, Lonca monotherapy demonstrated clinically meaningful efficacy and was well-tolerated in heavily pretreated Chinese patients with R/R DLBCL, which was consistent with the results of the LOTIS-2 study in Caucasian patients.

What Is This Summary About?: This article provides a plain-language summary of the results of a clinical trial called the LOTIS-2 study.The LOTIS-2 study included 145 participants with an aggressive type (one that forms, grows, or spreads quickly) of non-Hodgkin lymphoma called diffuse large B-cell lymphoma (a type of blood cancer), or DLBCL for short, whose disease came back or did not respond after 2 or more previous treatments. The LOTIS-2 study was conducted from August 2018 to September 2022.Participants received loncastuximab tesirine, also referred to as Lonca, for up to 1 year, or longer if the treatment was working, and their health was monitored. The primary purpose of the LOTIS-2 study was to find out if participants' lymphoma shrank partially or completely after receiving Lonca., What Were the Results?: A total of 145 participants who were treated with Lonca lived a median (meaning the middle value in a set of numbers) of 9.5 months after starting Lonca treatment. The lymphoma shrank partially or completely in nearly half of participants and shrank completely in 1 in 4 participants. Among participants whose disease either shrank partially or completely in response to Lonca treatment, responses happened relatively quickly, with a median time to response (the time between starting treatment and when the participant's lymphoma either partially or completely shrank) of 41 days. In these participants, the lymphoma did not grow or come back for a median of 13.4 months. Researchers estimated that 83% of participants whose disease shrank completely remained disease free for at least 1 year.Nearly all participants had a side effect from Lonca treatment. The most common side effects were abnormal liver tests (increased gamma-glutamyl transferase), decreased white blood cells (neutropenia), and decreased platelets (thrombocytopenia). One in 4 participants had their treatment stopped due to side effects. The most common side effects that resulted in participants needing to stop Lonca treatment were abnormal liver tests (increased gamma-glutamyl transferase), swelling in the arms or legs (peripheral edema), swelling in an individual spot (localized edema), and fluid around the lungs (pleural effusion)., What Do the Results of the Study Mean?: These results show that Lonca is a treatment option with controllable side effects for many patients with DLBCL whose disease did not respond or came back after 2 or more previous treatments. For participants whose lymphoma completely shrank while taking Lonca, those responses to treatment occurred quickly and lasted for over a year.

What Is This Summary About?: In this article, we summarize results from a clinical study called LOTIS-2, in which researchers looked at patients with a type of blood cancer called diffuse large B-cell lymphoma, or DLBCL for short. Patients received the drug loncastuximab tesirine, or Lonca for short, which targets a marker on the surface of tumor cells called CD19.Patient information from the LOTIS-2 study, other studies of Lonca, and information from scientific publications was used to develop a quantitative systems pharmacology (QSP) model, which can predict how Lonca works in the body. The goal was to use the QSP model to see if CD19 levels can predict tumor size changes after Lonca treatment and if Lonca can still work to treat DLBCL when CD19 levels are very low. The prior LOTIS-1 and LOTIS-2 trials demonstrated an acceptable safety profile for Lonca, and therefore the current study did not evaluate safety data., What Were the Results?: Researchers used immunohistochemistry, a common technique to evaluate CD19 expression. They found that there was no association between patients who responded to Lonca treatment and levels of CD19 on their tumor cells. Some patients with low or even undetectable levels of CD19 on their tumor cells had observable decreases in tumor size after Lonca treatment., What Do the Results of the Study Mean?: While Lonca uses the CD19 target to find and destroy cancer cells, Lonca does not require a large amount of CD19 to kill tumor cells. These results mean that Lonca may be an effective treatment for patients with DLBCL, even if CD19 expression in tumors is undetectable by immunohistochemistry.

Antibody-drug conjugates (ADCs) represent one of the most successful therapeutic approaches introduced in clinical practice in the last few years. Loncastuximab tesirine (ADCT-402) is a CD19 targeting ADC, in which the antibody is conjugated through a protease cleavable dipeptide linker to a pyrrolobenzodiazepine (PBD) dimer warhead (SG3199). Based on the results of a phase 2 study, loncastuximab tesirine was recently approved for adult patients with relapsed/refractory large B-cell lymphoma. We assessed the activity of loncastuximab tesirine using in vitro and in vivo models of lymphomas, correlated its activity with CD19 expression levels, and identified combination partners providing synergy with loncastuximab tesirine. Loncastuximab tesirine was tested across 60 lymphoma cell lines. Loncastuximab tesirine had strong cytotoxic activity in B-cell lymphoma cell lines. The in vitro activity was correlated with CD19 expression level and intrinsic sensitivity of cell lines to the ADC’s warhead. Loncastuximab tesirine was more potent than other anti-CD19 ADCs (coltuximab ravtansine, huB4-DGN462), albeit the pattern of activity across cell lines was correlated. Loncastuximab tesirine activity was also largely correlated with cell line sensitivity to R-CHOP. Combinatorial in vitro and in vivo experiments identified the benefit of adding loncastuximab tesirine to other agents, especially BCL2 and PI3K inhibitors. Our data support the further development of loncastuximab tesirine as a single agent and in combination for patients affected by mature B-cell neoplasms. The results also highlight the importance of CD19 expression and the existence of lymphoma populations characterized by resistance to multiple therapies.

Three critically ill, chemotherapy-refractory patients with diffuse large B-cell lymphoma (DLBCL) received loncastuximab tesirine in conjunction with standard therapies for secondary malignancy-associated hemophagocytic lymphohistiocytosis (Mal-HLH). All patients were treated inpatient, with one requiring intubation on the day of administration. Each patient had an H-score >238, indicating a >98% probability of HLH. A significant reduction in ferritin levels was observed in two patients, and one patient achieved a complete response (CR). Loncastuximab tesirine demonstrated promise in managing Mal-HLH where previous treatments had failed. This study suggests that loncastuximab tesirine exhibits favorable activity and should be considered a valuable addition to the treatment options for Mal-HLH driven by DLBCL., Competing Interests: Human subjects: Consent was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Schieber et al.)

Currently, a significant percentage of patients with DLBCL are refractory or relapse after a first line of immunochemotherapy. Second relapses after autologous stem cell transplantation or chimeric antigen receptor T-cell therapies present few treatment options and do not yield good results. New molecules have entered the immunotherapy arsenal. Loncastuximab tesirine comprises a humanized anti-CD19 monoclonal conjugated antibody, which consists of an anti-CD19 antibody and cytotoxic alkylating agent, SG3199. Several studies have proven its efficacy in the treatment of refractory cases of DLBCL with a good safety profile, with the main adverse effects being neutropenia, thrombopenia, and liver enzyme involvement. In this review, we explain the mechanism of action of this molecule, the clinical data that have led to its acceptance by the FDA, and the new therapeutic options that are proposed in association with this drug.

Therapies that demonstrate durable, long-term responses with manageable safety and tolerability are needed for patients with relapsed/refractory diffuse large B-cell lymphoma (R/R DLBCL). Loncastuximab tesirine (loncastuximab tesirine-lpyl [Lonca]), an anti-CD19 antibody conjugated to a potent pyrrolobenzodiazepine dimer, demonstrated single-agent antitumor activity in the pivotal phase II LOTIS-2 study in heavily pretreated patients with R/R DLBCL. Here we present updated efficacy and safety analyses from LOTIS-2, performed for all patients and in subsets of patients with a complete response (CR), including patients with CR who were event-free (no progressive disease or death) for ≥1 year and ≥2 years from cycle 1, day 1 of treatment. Lonca was administered every 3 weeks (0.15 mg/kg for 2 cycles; 0.075 mg/kg for subsequent cycles). As of the final data cutoff (September 15, 2022; median follow-up: 7.8 months [range, 0.3-42.6]), 70 of 145 (48.3%) patients achieved an overall response. Thirty-six (24.8%) patients achieved CR, of which 16 (44%) and 11 (31%) were event-free for ≥1 year and ≥2 years, respectively. In the all-treated population, the median overall survival was 9.5 months; the median progression-free survival was 4.9 months. Among patients with CR, median overall survival and progression-free survival were not reached, with 24-month overall and progression-free survival rates of 68.2% (95% CI: 50.0-81.0) and 72.5% (95% CI: 48.2-86.8), respectively. No new safety concerns were detected. With additional follow-up, Lonca continued to demonstrate durable, long-term responses with manageable safety and tolerability in patients with CR (clinicaltrials gov. Identifier: NCT03589469).