Impaired T and "memory-like" NK-cell reconstitution is linked to late-onset HCMV reactivation after letermovir cessation.

Allogeneic hematopoietic stem cell transplantation (alloSCT) is the only cure for many hematologic malignancies. However, alloSCT recipients are susceptible to opportunistic pathogens such as human cytomegalovirus (HCMV). Letermovir prophylaxis has revolutionized HCMV management, but the challenge of late HCMV reactivations has emerged. Immunological surrogates of clinically significant HCMV reactivations (csCMVi) after discontinuation of letermovir remain to be defined. Therefore, we studied NK-cell reconstitution along with the global and HCMV pp65-specific T-cell repertoire of 24 alloSCT recipients at seven timepoints before (day +90) and after (days +120-270) cessation of letermovir prophylaxis. Patients who experienced csCMVi had lower counts of IFNγ+ HCMV-specific CD4+ and CD8+ T cells than HCMV controllers. Furthermore, csCMVi patients displayed late impairment of NK-cell reconstitution, especially suppression of "memory-like" CD159c+CD56dim NK-cell counts that preceded csCMVi events in most patients. Moreover, several surrogates of immune reconstitution were associated with the severity of HCMV manifestation, with patients suffering from HCMV end-organ disease and/or refractory HCMV infection harboring least HCMV-specific T cells and "memory-like" NK cells. Altogether, our findings establish an association of delayed or insufficient proliferation of both HCMV-specific T cells and "memory-like" NK cells with csCMVi and the severity of HCMV manifestations following discontinuation of letermovir prophylaxis.

C-X-C Motif Chemokine Receptor 4-Targeted Radioligand Therapy in Hematological Malignancies-Myeloablative Effects, Antilymphoma Activity, and Safety Profile.

BACKGROUND: After C-X-C motif chemokine receptor 4 (CXCR4)-directed radioligand therapy (RLT), lymphoma patients are scheduled for conditioning therapy (CON) followed by hematopoietic stem cell transplantation (HSCT). We aimed to determine whether CXCR4-RLT can achieve bone marrow ablation and direct antilymphoma activity independent from CON/HSCT and also evaluated the safety profile of this theranostic approach in an acute setting. PATIENTS AND METHODS: After CXCR4-directed 68 Ga-pentixafor PET/CT, 21 heavily pretreated patients with hematological malignancies underwent CXCR4-directed RLT using 90 Y-pentixather. The extent of myeloablative efficacy was determined by investigating hematologic laboratory parameters before RLT (day -1), at the day of RLT (day 0), 2 days after RLT (day 2), and before CON (median day 10). Serving as surrogate marker of antilymphoma activity, lactate dehydrogenase (LDH) levels were also assessed until CON. We also screened for laboratory-defined tumor lysis syndrome after the Cairo-Bishop definition and recorded acute laboratory adverse events using the Common Terminology Criteria for Adverse Events version 5.0. RESULTS: After RLT, we observed a significant decline of leukocyte levels by 79.4% ± 18.7% till CON (granulocytes, drop by 70.3% ± 21%; platelets, reduction by 43.1% ± 36%; P ≤ 0.0005 vs day 0, respectively). After RLT, LDH levels already reached a peak at day 2, which was followed by a rapid decline thereafter (peak vs day of CON, P = 0.0006), indicating that 90 Y-pentixather exhibits direct antilymphoma activity. At day of CON, LDH levels were also significantly lower when compared with day -1 ( P = 0.04), suggestive for durable response mediated by RLT. No patient fulfilled the criteria of tumor lysis syndrome, whereas 25 laboratory adverse events attributable to CXCR4-directed treatment were identified (≥grade 3 in 2/25 [8%]). During further treatment course, all patients (100%) received HSCT. CONCLUSIONS: CXCR4-directed RLT causes effective myeloablation, which allows for HSCT. In addition, it also exerts direct antilymphoma activity independent of subsequent therapeutic steps, whereas safety profile was acceptable.

Identification of novel canonical and cryptic HCMV-specific T-cell epitopes for HLA-A∗03 and HLA-B∗15 via peptide-PRISM.

ABSTRACT: Human cytomegalovirus (HCMV) reactivation poses a substantial risk to patients receiving tranplants. Effective risk stratification and vaccine development is hampered by a lack of HCMV-derived immunogenic peptides in patients with common HLA-A∗03:01 and HLA-B∗15:01 haplotypes. This study aimed to discover novel HCMV immunogenic peptides for these haplotypes by combining ribosome sequencing (Ribo-seq) and mass spectrometry with state-of-the-art computational tools, Peptide-PRISM and Probabilistic Inference of Codon Activities by an EM Algorithm. Furthermore, using machine learning, an algorithm was developed to predict immunogenicity based on translational activity, binding affinity, and peptide localization within small open reading frames to identify the most promising peptides for in vitro validation. Immunogenicity of these peptides was subsequently tested by analyzing peptide-specific T-cell responses of HCMV-seropositive and -seronegative healthy donors as well as patients with transplants. This resulted in the direct identification of 3 canonical and 1 cryptic HLA-A∗03-restricted immunogenic peptides as well as 5 canonical and 1 cryptic HLA-B∗15-restricted immunogenic peptide, with a specific interferon gamma-positive (IFN-γ+)/CD8+ T-cell response of ≥0.02%. High T-cell responses were detected against 2 HLA-A∗03-restricted and 3 HLA-B∗15-restricted canonical peptides with frequencies of up to 8.77% IFN-γ+/CD8+ T cells in patients after allogeneic stem cell transplantation. Therefore, our comprehensive strategy establishes a framework for efficient identification of novel immunogenic peptides from both existing and novel Ribo-seq data sets.

CD4+ T cells are the major predictor of HCMV control in allogeneic stem cell transplant recipients on letermovir prophylaxis.

Introduction: Human cytomegalovirus (HCMV) causes significant morbidity and mortality in allogeneic stem cell transplant (alloSCT) recipients. Recently, antiviral letermovir prophylaxis during the first 100 days after alloSCT replaced PCR-guided preemptive therapy as the primary standard of care for HCMV reactivations. Here, we compared NK-cell and T-cell reconstitution in alloSCT recipients receiving preemptive therapy or letermovir prophylaxis in order to identify potential biomarkers predicting prolonged and symptomatic HCMV reactivation. Methods: To that end, the NK-cell and T-cell repertoire of alloSCT recipients managed with preemptive therapy (n=32) or letermovir prophylaxis (n=24) was characterized by flow cytometry on days +30, +60, +90 and +120 after alloSCT. Additionally, background-corrected HCMV-specific T-helper (CD4+IFNγ+) and cytotoxic (CD8+IFNγ+CD107a+) T cells were quantified after pp65 stimulation. Results: Compared to preemptive therapy, letermovir prophylaxis prevented HCMV reactivation and decreased HCMV peak viral loads until days +120 and +365. Letermovir prophylaxis resulted in decreased T-cell numbers but increased NK-cell numbers. Interestingly, despite the inhibition of HCMV, we found high numbers of "memory-like" (CD56dimFcεRIγ- and/or CD159c+) NK cells and an expansion of HCMV-specific CD4+ and CD8+ T cells in letermovir recipients. We further compared immunological readouts in patients on letermovir prophylaxis with non/short-term HCMV reactivation (NSTR) and prolonged/symptomatic HCMV reactivation (long-term HCMV reactivation, LTR). Median HCMV-specific CD4+ T-cell frequencies were significantly higher in NSTR patients (day +60, 0.35 % vs. 0.00 % CD4+IFNγ+/CD4+ cells, p=0.018) than in patients with LTR, whereas patients with LTR had significantly higher median regulatory T-cell (Treg) frequencies (day +90, 2.2 % vs. 6.2 % CD4+CD25+CD127dim/CD4+ cells, p=0.019). ROC analysis confirmed low HCMV specific CD4+ (AUC on day +60: 0.813, p=0.019) and high Treg frequencies (AUC on day +90: 0.847, p=0.021) as significant predictors of prolonged and symptomatic HCMV reactivation. Discussion: Taken together, letermovir prophylaxis delays HCMV reactivation and alters NK- and T-cell reconstitution. High numbers of HCMV-specific CD4+ T cells and low numbers of Tregs seem to be pivotal to suppress post-alloSCT HCMV reactivation during letermovir prophylaxis. Administration of more advanced immunoassays that include Treg signature cytokines might contribute to the identification of patients at high-risk for long-term and symptomatic HCMV reactivation who might benefit from prolonged administration of letermovir.

Clinical validation and assessment of feasibility of volumetric absorptive microsampling (VAMS) for monitoring of nilotinib, cabozantinib, dabrafenib, trametinib, and ruxolitinib.

Volumetric absorptive microsampling (VAMS) has emerged as a minimally invasive alternative to conventional sampling. However, the applicability of VAMS must be investigated clinically. Therefore, the feasibility of at-home sampling was investigated for the kinase inhibitors nilotinib, cabozantinib, dabrafenib, trametinib and ruxolitinib and evaluated regarding the acceptance of at-home microsampling, sample quality of at-home VAMS and incurred sample stability. In addition, clinical validation including three different approaches for serum level predictions was performed. For this purpose, VAMS and reference serum samples were collected simultaneously. Conversion of VAMS to serum concentration was based either on a linear regression model, a hematocrit-dependent formula, or using a correction factor. During the study period 591 VAMS were collected from a total of 59 patients. The percentage of patients who agreed to perform VAMS at home ranged from 50.0 % to 84.6 % depending on the compound. 93.1 % of at-home VAMS were collected correctly. Regarding the drug stability in dried capillary blood, no stability issues were detected between on-site and at-home VAMS. Linear regression showed a strong correlation between VAMS and reference serum concentrations for nilotinib, cabozantinib, dabrafenib and ruxolitinib (r 0.9427 - 0.9674) and a moderate correlation for trametinib (r 0.5811). For clinical validation, the acceptance criteria were met for all three approaches for three of the five kinase inhibitors. Predictive performance was not improved by using individual hematocrit instead of population hematocrit and was largely independent of conversion model. In conclusion, VAMS at-home has been shown to be feasible for use in routine clinical care and serum values could be predicted based on the measured VAMS concentration for nilotinib, cabozantinib, and dabrafenib.

C-X-C Motif Chemokine Receptor 4-Targeted Radioligand Therapy in Patients with Advanced T-Cell Lymphoma.

C-X-C motif chemokine receptor 4 (CXCR4)-targeted radioligand therapy (RLT) has already been applied to advanced blood cancers, such as multiple myeloma or diffuse large B-cell lymphoma. We present a series of patients with advanced T-cell lymphoma (TCL) who were scheduled for CXCR4-directed therapy as a conditioning regimen, followed by hematopoietic stem cell transplantation (HSCT). Methods: Four patients with advanced, heavily pretreated, and relapsed TCL (2 men, 2 women; median age, 50 y) without suitable alternative therapeutic options underwent CXCR4-directed PET and pretherapeutic dosimetry. We then conducted CXCR4-targeted RLT in combination with allogeneic (3/4, 75%) or autologous (1/4, 25%) HSCT. One patient also underwent radioimmunotherapy targeting CD66 to enhance therapeutic efficacy. We investigated safety, best response, progression-free survival, and overall survival. Results: Pretherapeutic dosimetry indicated lymphoma-absorbed doses of up to 33.2 Gy from CXCR4-targeted RLT. Except for 1 patient who developed tumor lysis syndrome along with transient grade 3 kidney failure, no acute toxicity, allergic reactions, or other adverse events were recorded during therapy. One patient developed septicemia and subsequently died 16 d after RLT, whereas engraftment was achieved in the remaining 3 patients (75%). During follow-up, a partial response was recorded in 1 of 3 patients (33.3%) and a complete metabolic response in the other two (66.7%, with 1 patient also receiving additional radioimmunotherapy). Median progression-free survival was 7 mo (range, 4-25 mo). After a median follow-up of 54 mo (range, 4-56 mo), 3 patients were still alive at the date of censoring. Conclusion: For advanced, heavily pretreated TCL, CXCR4-directed RLT may serve as an effective conditioning therapy before HSCT and can cause substantial antilymphoma activity, leading to a remarkable response in selected cases.

A Physiologically-Based Pharmacokinetic Model of Ruxolitinib and Posaconazole to Predict CYP3A4-Mediated Drug-Drug Interaction Frequently Observed in Graft versus Host Disease Patients.

Ruxolitinib (RUX) is approved for the treatment of steroid-refractory acute and chronic graft versus host disease (GvHD). It is predominantly metabolized via cytochrome P450 (CYP) 3A4. As patients with GvHD have an increased risk of invasive fungal infections, RUX is frequently combined with posaconazole (POS), a strong CYP3A4 inhibitor. Knowledge of RUX exposure under concomitant POS treatment is scarce and recommendations on dose modifications are inconsistent. A physiologically based pharmacokinetic (PBPK) model was developed to investigate the drug-drug interaction (DDI) between POS and RUX. The predicted RUX exposure was compared to observed concentrations in patients with GvHD in the clinical routine. PBPK models for RUX and POS were independently set up using PK-Sim® Version 11. Plasma concentration-time profiles were described successfully and all predicted area under the curve (AUC) values were within 2-fold of the observed values. The increase in RUX exposure was predicted with a DDI ratio of 1.21 (Cmax) and 1.59 (AUC). Standard dosing in patients with GvHD led to higher RUX exposure than expected, suggesting further dose reduction if combined with POS. The developed model can serve as a starting point for further simulations of the implemented DDI and can be extended to further perpetrators of CYP-mediated PK-DDIs or disease-specific physiological changes.

Volumetric absorptive microsampling (VAMS) for the quantification of ten kinase inhibitors and determination of their in vitro VAMS-to-plasma ratio.

Personalized dosing of kinase inhibitors (KI) might be beneficial in oral anti-cancer therapy to overcome individual pharmacokinetic variability. Volumetric absorptive microsampling (VAMS) has emerged as an attractive alternative compared to conventional invasive sampling methods enabling remote and frequent specimen collection. Therefore, an LC-MS/MS VAMS method was developed and validated to monitor drug exposure of ten KI from 20 µL dried capillary blood. The assay includes the KI cabozantinib, dabrafenib, nilotinib, and osimertinib with a calibration range of 6-1500 ng/mL and afatinib, axitinib, bosutinib, lenvatinib, ruxolitinib and trametinib within a range of 2-500 ng/mL. Using acetonitrile containing isotope labelled internal standards (IS) as solid-liquid extraction solvent, analytes and IS were detected by multiple reaction monitoring (MRM) after electro-spray ionization (ESI) in positive ionization mode after chromatographic separation using a phenyl-hexyl column. The method was validated according to the FDA and EMA guidelines for bioanalytical method validation and in accordance with the guideline of the International Association for Therapeutic Drug Monitoring and Clinical Toxicology for dried blood spot-based methods. The calibration model was linear and reproducible for all KI (R2> 0.994). Furthermore, the validation demonstrated that the VAMS method is accurate, precise, and sensitive. The method fulfilled the acceptance criteria for matrix effects, recovery, carry over, selectivity as well as for the haematocrit effect and all substances proved to be stable in dried condition for at least six weeks at room temperature. In vitro experiments using spiked venous blood were conducted to establish a VAMS-to-plasma conversion factor for each analyte for comparison of VAMS and plasma concentrations. The method was successfully used in a real-life setting demonstrating its applicability in clinical routine. VAMS concentrations of afatinib, cabozantinib, dabrafenib, nilotinib, ruxolitinib and trametinib were assessed in capillary blood samples collected from either trained healthcare professionals or patients at home.

Pulmonary Imaging of Immunocompromised Patients during Hematopoietic Stem Cell Transplantation using Non-Contrast-Enhanced Three-Dimensional Ultrashort Echo Time (3D-UTE) MRI.

PURPOSE: To evaluate the feasibility of non-contrast-enhanced three-dimensional ultrashort echo time (3D-UTE) MRI for pulmonary imaging in immunocompromised patients during hematopoietic stem cell transplantation (HSCT). METHODS: MRI was performed using a stack-of-spirals 3D-UTE sequence (slice thickness: 2.34mm; matrix: 256 × 256; acquisition time: 12.7-17.6 seconds) enabling imaging of the entire thorax within single breath-holds. Patients underwent MRI before HSCT initiation, in the case of periprocedural pneumonia, before discharge, and in the case of re-hospitalization. Two readers separately assessed the images regarding presence of pleural effusions, ground glass opacities (GGO), and consolidations on a per lung basis. A T2-weighted (T2w) multi-shot Turbo Spin Echo sequence (BLADE) was acquired in coronal orientation during breath-hold (slice thickness: 6.00mm; matrix: 320 × 320; acquisition time: 3.1-5.5 min) and read on a per lesion basis. Low-dose CT scans in inspiration were used as reference and were read on a per lung basis. Only scans performed within a maximum of three days were included in the inter-method analyses. Interrater agreement, sensitivity, specificity, positive and negative predictive values, and diagnostic accuracy of 3D-UTE MRI were calculated. RESULTS: 67 MRI scans of 28 patients were acquired. A reference CT examination was available for 33 scans of 23 patients. 3D-UTE MRI showed high sensitivity and specificity regarding pleural effusions (n = 6; sensitivity, 92 %; specificity, 100 %) and consolidations (n = 22; sensitivity 98 %, specificity, 86 %). Diagnostic performance was lower for GGO (n = 9; sensitivity, 63 %; specificity, 84 %). Accuracy rates were high (pleural effusions, 98 %; GGO, 79 %; consolidations 94 %). Interrater agreement was substantial for consolidations and pleural effusions (κ = 0.69-0.82) and moderate for GGO (κ = 0.54). Compared to T2w imaging, 3D-UTE MRI depicted the assessed pathologies with at least equivalent quality and was rated superior regarding consolidations and GGO in ~50 %. CONCLUSION: Non-contrast 3D-UTE MRI enables radiation-free assessment of typical pulmonary complications during HSCT procedure within a single breath-hold. Yet, CT was found to be superior regarding the identification of pure GGO changes. KEY POINTS: · 3D-UTE MRI of the thorax can be acquired within a single breath-hold.. · 3D-UTE MRI provides diagnostic imaging of pulmonary consolidations and pleural effusions.. · 3D-UTE sequences improve detection rates of ground glass opacities on pulmonary MRI.. · 3D-UTE MRI depicts pulmonary pathologies at least equivalent to T2-weighted Blade sequence.. CITATION FORMAT: · Metz C, Böckle D, Heidenreich JF et al. Pulmonary Imaging of Immunocompromised Patients during Hematopoietic Stem Cell Transplantation using Non-Contrast-Enhanced Three-Dimensional Ultrashort Echo Time (3D-UTE) MRI. Fortschr Röntgenstr 2022; 194: 39 - 48.

Ruxolitinib exposure in patients with acute and chronic graft versus host disease in routine clinical practice-a prospective single-center trial.

PURPOSE: Knowledge on Ruxolitinib exposure in patients with graft versus host disease (GvHD) is scarce. The purpose of this prospective study was to analyze Ruxolitinib concentrations of GvHD patients and to investigate effects of CYP3A4 and CYP2C9 inhibitors and other covariates as well as concentration-dependent effects. METHODS: 262 blood samples of 29 patients with acute or chronic GvHD who were administered Ruxolitinib during clinical routine were analyzed. A population pharmacokinetic model obtained from myelofibrosis patients was adapted to our population and was used to identify relevant pharmacokinetic properties and covariates on drug exposure. Relationships between Ruxolitinib exposure and adverse events were assessed. RESULTS: Median of individual mean trough serum concentrations was 39.9 ng/mL at 10 mg twice daily (IQR 27.1 ng/mL, range 5.6-99.8 ng/mL). Applying a population pharmacokinetic model revealed that concentrations in our cohort were significantly higher compared to myelofibrosis patients receiving the same daily dose (p < 0.001). Increased Ruxolitinib exposure was caused by a significant reduction in Ruxolitinib clearance by approximately 50%. Additional comedication with at least one strong CYP3A4 or CYP2C9 inhibitor led to a further reduction by 15% (p < 0.05). No other covariate affected pharmacokinetics significantly. Mean trough concentrations of patients requiring dose reduction related to adverse events were significantly elevated (p < 0.05). CONCLUSION: Ruxolitinib exposure is increased in GvHD patients in comparison to myelofibrosis patients due to reduced clearance and comedication with CYP3A4 or CYP2C9 inhibitors. Elevated Ruxolitinib trough concentrations might be a surrogate for toxicity.

Quantification of letermovir in human serum using high-performance liquid chromatography with diode array detection.

A simple, rapid, cost-effective and sensitive high-performance liquid chromatography method with diode array detection was developed and validated for the quantification of letermovir, a compound approved for prophylaxis of cytomegalovirus infection and disease in adult recipients of an allogeneic hematopoietic stem cell transplant. Sorafenib was used as internal standard. Samples were pre-treated by liquid-liquid extraction with tert-butyl methylether. Separation was achieved on a XTerra® RP18 column (150 × 2.1 mm, 5 µm) at 30 °C using gradient elution with a mobile phase of 20 mM ammonium bicarbonate pH 7.9 (mobile phase A) and acetonitrile:20 mM ammonium bicarbonate (9:1 v/v) (mobile phase B). Samples were eluted at a flow rate of 0.3 mL/min throughout the 20-min run. UV wavelength mode was used, letermovir and sorafenib were monitored at 260 nm. The calibration curve was linear in a concentration range of 25-5000 ng/mL with correlation coefficients ≥ 0.99. Intra-day and inter-day accuracy expressed as relative error were -11.4-20% and -7.96-10.62%, respectively. Precision expressed as coefficient of variation was 1.44-3.15% (intra-day) and 1.17-1.93% (inter-day). The method was successfully applied for analysis of 128 letermovir levels demonstrating its usefulness for letermovir monitoring in routine clinical practice.

Prostaglandin E2 in a TLR3- and 7/8-agonist-based DC maturation cocktail generates mature, cytokine-producing, migratory DCs but impairs antigen cross-presentation to CD8+ T cells.

Mature dendritic cells (DCs) represent cellular adjuvants for optimal antigen presentation in cancer vaccines. Recently, a combination of prostaglandin E2 (PGE2) with Toll-like receptor agonists (TLR-P) was proposed as a new standard to generate superior cytokine-producing DCs with high migratory capacity. Here, we compare TLR-P DCs with conventional DCs matured only with the proinflammatory cytokines TNFα and IL-1ß (CDCs), focussing on the interaction of resulting DCs with CD8+ T-cells. TLR-P matured DCs showed elevated expression of activation markers such as CD80 and CD83 compared to CDCs, together with a significantly higher migration capacity. Secretion of IL-6, IL-8, IL-10, and IL-12 was highest after 16 h in TLR-P DCs, and only TLR-P DCs secreted active IL-12p70. TLR-P DCs as well as CDCs successfully primed multifunctional CD8+ T-cells from naïve precursors specific for the peptide antigens Melan-A, NLGN4X, and PTP with comparable priming efficacy and T-cell receptor avidity. CD8+ T-cells primed by TLR-P DCs showed significantly elevated expression of the integrin VLA-4 and a trend for higher T-cell numbers after expansion. In contrast, TLR-P DCs displayed a substantially reduced capability to cross-present CMVpp65 protein antigen to pp65-specific T cells, an effect that was dose-dependent on PGE2 during DC maturation and reproducible with several responder T-cell lines. In conclusion, TLR-P matured DCs might be optimal presenters of antigens not requiring processing such as short peptides. However, PGE2 seems less favorable for maturation of DCs intended to process and cross-present more complex vaccine antigens such as lysates, proteins or long peptides.

Excretion of Ascaris lumbricoides following reduced-intensity allogeneic hematopoietic stem cell transplantation and consecutive treatment with mebendazole.

Here, we present the unique case of a 51-year-old German patient with multiple myeloma excreting Ascaris lumbricoides in his stool five weeks after allogeneic hematopoietic stem cell transplantation. Stool analysis remained negative for the presence of eggs, and there was no eosinophilia in the peripheral blood at any time around stem cell transplantation. The patient was commenced on a three-day treatment with mebendazole, which was well tolerated. No serious interactions with the concomitant post-transplant medication or negative effects on the hematopoiesis were observed, and the myeloma still is in complete remission. To our knowledge, this is the first report on excretion of A lumbricoides in the context of allogeneic stem cell transplantation. The case is remarkable with view to the fact that the parasite has supposedly survived all courses of myeloma treatment including autologous and allogeneic conditioning. Parasitosis with A lumbricoides has a worldwide prevalence of about a billion and is extremely rare in northern Europe. Possibly the patient got infected during a trip to Egypt years before multiple myeloma was diagnosed.

Side Effects of CXC-Chemokine Receptor 4-Directed Endoradiotherapy with Pentixather Before Hematopoietic Stem Cell Transplantation.

The chemokine receptor CXC-chemokine receptor 4 (CXCR4) is a transmembrane receptor involved in survival, proliferation, and dissemination of different cancers, including hematopoietic malignancies. Relapsed or refractory hematopoietic cancers are frequently resistant to conventional therapy, and novel highly active strategies are urgently needed. CXCR4-directed endoradiotherapy constitutes a highly promising targeted therapeutic concept. Here, we investigated the adverse effects of this novel treatment approach. Methods: Twenty-two patients with heavily pretreated lymphoproliferative or myeloid malignancies were treated with 177Lu- or 90Y-pentixather-a CXCR4-directed therapeutic radioligand-before conventional conditioning therapy followed by autologous or allogeneic hematopoietic stem cell transplantation. Twenty-five CXCR4-directed endoradiotherapies were administered to those patients. Adverse events occurring between endoradiotherapy and the start of conventional conditioning therapy were retrospectively analyzed and graded for the estimation of the safety profile. Results: CXCR4-directed endoradiotherapy with pentixather showed a favorable toxicity profile. As expected, the hematopoietic system was most affected, with all subjects developing cytopenias. Except for 1 acute kidney failure, grade 3, due to tumor lysis syndrome, overall nephro- and hepatotoxicity was low. Other higher-grade adverse events were either transient and resolved or easily manageable. Conclusion: Therapy with radiolabeled pentixather appears to be well tolerated and easily applicable when preceding conventional conditioning regimens for hematopoietic stem cell transplantation.

Feasibility of CXCR4-Directed Radioligand Therapy in Advanced Diffuse Large B-Cell Lymphoma.

We have recently reported on our experience with C-X-C-motif chemokine receptor 4 (CXCR4)-directed radioligand therapy (RLT) in multiple myeloma and acute leukemia. Methods: Six patients with heavily pretreated relapsed diffuse large B-cell lymphoma (3 men, 3 women; aged, 54 ± 8 y) underwent CXCR4-directed RLT in combination with conditioning chemotherapy and allogeneic stem cell transplantation. In 2 patients, radioimmunotherapy targeting CD20 or CD66 was added to enhance antilymphoma activity. Endpoints were incidence and severity of adverse events, progression-free survival, and overall survival. Results: RLT and additional radioimmunotherapy were well tolerated, without any acute adverse events or changes in vital signs. Successful engraftment was recorded after a median of 11 d (range, 9-13 d). Of the 4 patients who were available for follow-up (one patient died of CNS aspergillosis 29 d after RLT and another of sepsis in aplasia 34 d after RLT), CXCR4-directed RLT resulted in a partial response in two (both treated with additional radioimmunotherapy) and a mixed response in the remaining two. The response duration was rather short-lived, with a median progression-free survival of 62 d (range, 29-110 d) and a median overall survival of 76 d (range, 29-334 d). Conclusion: CXCR4-directed RLT (in combination with additional radioimmunotherapy) is feasible as a conditioning regimen before allogeneic stem cell transplantation in diffuse large B-cell lymphoma.

Prognostic value of [18F]FDG-PET/CT in multiple myeloma patients before and after allogeneic hematopoietic cell transplantation.

PURPOSE: Despite improved treatment options, multiple myeloma (MM) remains an incurable disease. The aim of this study was to investigate the prognostic value of positron emission tomography/computed tomography (PET/CT) using 18F-2'-deoxy-2'-fluorodeoxyglucose ([18F]FDG) in MM patients shortly before and ~100 days after allogeneic hematopoietic cell transplantation (allo-HCT). METHODS: In this retrospective analysis, we evaluated [18F]FDG-PET/CT-scans of 45 heavily pre-treated MM patients before and 27 patients after scheduled allo-HCT. All scans were qualitatively and semi-quantitatively assessed for the presence of active disease. Serological response was recorded according to International Myeloma Working Group (IMWG) criteria. Progression-free (PFS) and overall survival (OS) were correlated with different PET/CT-derived parameters, such as presence, number and maximum standardized uptake value (SUVmax) of focal myeloma lesions. The impact of extramedullary disease on patient outcome was also assessed. RESULTS: PET/CT negativity -prior to or following allo-HCT- was a favorable prognostic factor for progression-free and overall survival (both, PFS and OS: pre-HSCT p < 0.001, post-HCT p < 0.005). High FDG-uptake (SUVmax > 6.5) revealed a significantly shortened survival compared to patients with a lower SUVmax (<6.5) (OS, 5.0 ± 1.1 m vs. not reached - longest 122.0 m; p < 0.001). Moreover, our data prove that a higher number (>3) of focal lesions (pre-HCT: both PFS and OS: p < 0.001; post-HCT PFS: p < 0.001, OS: p = 0.139) as well as the presence of extramedullary disease serve as adverse prognostic factors prior to and after allo-HCT. At response assessment after allo-HCT, [18F]FDG-PET/CT had a complementary value in prognostication in addition to IMWG criteria alone. CONCLUSION: [18F]FDG-PET/CT before and shortly after allogeneic HCT is a powerful predictor for progression-free and overall survival in MM patients.

Dual Targeting of Acute Leukemia and Supporting Niche by CXCR4-Directed Theranostics.

C-X-C chemokine receptor 4 (CXCR4) is a transmembrane receptor with pivotal roles in cell homing and hematopoiesis. CXCR4 is also involved in survival, proliferation and dissemination of cancer, including acute lymphoblastic and myeloid leukemia (ALL, AML). Relapsed/refractory ALL and AML are frequently resistant to conventional therapy and novel highly active strategies are urgently needed to overcome resistance. Methods: We used patient-derived (PDX) and cell line-based xenograft mouse models of ALL and AML to evaluate the efficacy and toxicity of a CXCR4-targeted endoradiotherapy (ERT) theranostic approach. Results: The positron emission tomography (PET) tracer 68Ga-Pentixafor enabled visualization of CXCR4 positive leukemic burden. In xenografts, CXCR4-directed ERT with 177Lu-Pentixather distributed to leukemia harboring organs and resulted in efficient reduction of leukemia. Despite a substantial in vivo cross-fire effect to the leukemia microenvironment, mesenchymal stem cells (MSCs) subjected to ERT were viable and capable of supporting the growth and differentiation of non-targeted normal hematopoietic cells ex vivo. Finally, three patients with refractory AML after first allogeneic hematopoietic stem cell transplantation (alloSCT) underwent CXCR4-directed ERT resulting in leukemia clearance, second alloSCT, and successful hematopoietic engraftment. Conclusion: Targeting CXCR4 with ERT is feasible and provides a highly efficient means to reduce refractory acute leukemia for subsequent cellular therapies. Prospective clinical trials testing the incorporation of CXCR4 targeting into conditioning regimens for alloSCT are highly warranted.

Peptide receptor radionuclide therapy as a new tool in treatment-refractory sarcoidosis - initial experience in two patients.

Sarcoidosis is a multisystem granulomatous disorder of unknown etiology that can involve virtually all organ systems. Whereas most patients present without symptoms, progressive and disabling organ failure can occur in up to 10% of subjects. Somatostatin receptor (SSTR)-directed peptide receptor radionuclide therapy (PRRT) has recently received market authorization for treatment of SSTR-positive neuroendocrine tumors. Methods: We describe the first case series comprising two patients with refractory multi-organ involvement of sarcoidosis who received 4 cycles of PRRT. Results: PRRT was well-tolerated without any acute adverse effects. No relevant toxicities could be recorded during follow-up. Therapy resulted in partial response accompanied by a pronounced reduction in pain (patient #1) and stable disease regarding morphology as well as disease activity (patient #2), respectively. Conclusion: Peptide receptor radionuclide therapy in sarcoidosis is feasible and might be a new valuable tool in patients with otherwise treatment-refractory disease. Given the long experience with and good tolerability of PRRT, further evaluation of this new treatment option for otherwise treatment-refractory sarcoidosis in larger patient cohorts is warranted.