JAK2-V617F–positive chronic myeloproliferative neoplasia (CMN) commonly displays dysfunction of integrins and adhesion molecules expressed on platelets, erythrocytes, and leukocytes. However, the mechanism by which the 2 major leukocyte integrin chains, β₁ and β₂, may contribute to CMN pathophysiology remained unclear. β₁ (α₄β₁; VLA-4) and β₂ (α_Lβ₂; LFA-1) integrins are essential regulators for attachment of leukocytes to endothelial cells. We here showed enhanced adhesion of granulocytes from mice with JAK2-V617F knockin (JAK2^+/VF mice) to vascular cell adhesion molecule 1– (VCAM1-) and intercellular adhesion molecule 1–coated (ICAM1-coated) surfaces. Soluble VCAM1 and ICAM1 ligand binding assays revealed increased affinity of β₁ and β₂ integrins for their respective ligands. For β₁ integrins, this correlated with a structural change from the low- to the high-affinity conformation induced by JAK2-V617F. JAK2-V617F triggered constitutive activation of the integrin inside-out signaling molecule Rap1, resulting in translocation toward the cell membrane. Employing a venous thrombosis model, we demonstrated that neutralizing anti–VLA-4 and anti–β₂ integrin antibodies suppress pathologic thrombosis as observed in JAK2^+/VF mice. In addition, aberrant homing of JAK2^+/VF leukocytes to the spleen was inhibited by neutralizing anti-β₂ antibodies and by pharmacologic inhibition of Rap1. Thus, our findings identified cross-talk between JAK2-V617F and integrin activation promoting pathologic thrombosis and abnormal trafficking of leukocytes to the spleen.

Small cell transformation (SCT) is a typical mechanism of adaptive resistance to third generation epidermal growth factor receptor inhibitors (EGFRi) which have become the standard of care for EGFR-driven non-small cell lung cancer (EGFR+ NSCLC). Little is known about the optimal management of SCT patients. This study aimed to compare outcomes under platinum/etoposide chemotherapy alone (chemo) or in combination with EGFR inhibitors (EGFRi+chemo) or immune checkpoint inhibitors (ICI+chemo). In addition, DLL3 expression was explored as potential novel therapeutic target. We conducted a retrospective study on patients with EGFR+ NSCLC and SCT treated at 19 centers in Europe and the United States. A total of 47 patients were included of whom 17 received chemo, 20 ICI+chemo, and 10 EGFRi+chemo. We analyzed DLL3 expression by immunohistochemistry. In the entire cohort, median overall survival (OS) from start of first SCT therapy was 11 months (95 % confidence interval [95 %CI] 9.1-12.9) and median progression-free survival (PFS) was 5 months (95 %CI 4.2-5.8). Median PFS was similar in all three groups (chemo and ICI+chemo 4 months, EGFRi+chemo 6 months), and 12-months PFS was 12 % (95 %CI 2 %-31 %), 13 % (95 %CI 0 %-43 %), and 0 % for ICI+chemo, EGFRi+chemo, and chemo, respectively. Median OS in the ICI+chemo group was 13 months (95 %CI 5.5-20.5) compared to 10 months (95 %CI 7.6-12.4) with chemo and EGFRi+chemo (95 %CI 8.1-11.9), respectively. Before and after SCT, 0 % and 93 % of tumors were DLL3-positive. Our results suggest that ICI+chemo and DLL3-targeting agents are worth further exploration in EGFR+ NSCLC undergoing SCT. Part of this work has been presented at ESMO annual meeting in Madrid, Spain in October 2023 (Poster 1336 P).

JAK2-V617F activates β1-integrin-mediated adhesion of granulocytes to vascular cell adhesion molecule 1

Objectives: Small-cell lung cancer (SCLC) is a lung malignancy with high relapse rates and poor survival outcomes. Treatment-resistant disease relapse occurs frequently and effective salvage therapies are urgently needed. Materials and Methods: We aimed to define efficacy and safety of checkpoint inhibitors (CPIs) in a heterogeneous population of relapsed and refractory SCLC patients in a large retrospective multicentric real-world cohort across German tertiary care centers. Results: A total of 111 patients from 11 treatment centers were included. Median age of all patients was 64 years, and 63% were male. Approximately one-third of all patients had poor performance status [Eastern Cooperative Oncology Group (ECOG) ⩾ 2], and 37% had known brain metastases. Patients were heavily pretreated with a median number of prior therapy lines of 2 (range, 1–8). Median follow-up of the entire cohort was 21.7 months. Nivolumab and Nivolumab/Ipilimumab were the most common regimens. Overall disease control rate was 27.2% in all patients and was numerically higher in CPI combination regimens compared with single-agent CPI (31.8% versus 23.8%; p = 0.16). Median overall survival (OS) was 5.8 months [95% confidence interval (CI), 1.7–9.9 months]. The 12- and 24-month survival rates were 31.8% and 12.7%, respectively. The 12-week death rate was 27.9%. Disease control and response rate were significantly lower in patients with liver metastases. Platinum sensitivity (to first-line treatment), metastatic burden, and lactate dehydrogenase (LDH) showed prognostic impact on survival in univariate analysis. Neutrophil-to-lymphocyte ratio (NLR) was a significant and independent predictor of survival in univariate ( p = 0.01) and multivariate analyses [hazard ratio (HR), 2.1; 95% CI = 1.1–4.1; p = 0.03]. Conclusion: CPI in patients with relapsed or refractory (R/R) SCLC is of limited value in an overall patient cohort; however, long-term survival, in particular with CPI combination strategies, is possible. Clinical characteristics allow a more differentiated subgroup selection, in particular patients with low NLR showed less benefit from CPI in R/R SCLC.

Oligometastatic (OMD) non‐small cell lung cancer (NSCLC) is a distinct but heterogeneous entity. Current guidelines recommend systemic therapy and consolidation with local ablative therapy (LAT). However, evidence regarding the optimal choice of multimodal treatment approaches is lacking, in particular with respect to the integration of immunotherapy. This real‐world study identified 218 patients with OMD NSCLC (2004–2023, prespecified criteria: ≤5 metastases in ≤2 organ systems) from three major German comprehensive cancer centers. Most patients had one (72.5%) or two (17.4%) metastatic lesions in a single (89.9%) organ system. Overall survival (OS) was significantly longer with a single metastatic lesion (HR 0.54, p = .003), and female gender (HR 0.4, p < .001). Median OS of the full cohort was 27.8 months, with 29% survival at 5 years. Patients who had completed LAT to all NSCLC sites, typically excluding patients with early progression, had a median OS of 34.4 months (37.7% 5‐year OS rate) with a median recurrence‐free survival (RFS) of 10.9 months (13.3% at 5 years). In those patients, systemic treatment as part of first‐line therapy was associated with doubling of RFS (12.3 vs. 6.4 months, p < .001). Despite limited follow‐up of patients receiving chemo‐immunotherapy (EU approval 2018/2019), RFS was greatly improved by adding checkpoint inhibitors to chemotherapy (HR 0.44, p = .008, 2‐year RFS 51.4% vs. 15.1%). In conclusion, patients with OMD NSCLC benefitted from multimodality approaches integrating systemic therapy and local ablation of all cancer sites. A substantial proportion of patients achieved extended OS, suggesting a potential for cure that can be further augmented with the addition of immunotherapy.