Melanie Janning

Acute myeloid leukemia (AML) represents a clonal disease of hematopoietic progenitors characterized by acquired heterogenous genetic changes that alter normal mechanisms of proliferation, self-renewal, and differentiation.(1) Although 40% to 45% of patients younger than 65 years of age can be cured with current therapies, only 10% of older patients reach long-term survival.(1) Because only very few novel AML drugs were approved in the past 2 decades, there is an urgent need to identify novel targets and therapeutic strategies to treat underserved AML patients. We report here that Axl, a member of the Tyro3, Axl, Mer receptor tyrosine kinase family,(2-4) represents an independent prognostic marker and therapeutic target in AML. AML cells induce expression and secretion of the Axl ligand growth arrest-specific gene 6 (Gas6) by bone marrow-derived stromal cells (BMDSCs). Gas6 in turn mediates proliferation, survival, and chemoresistance of Axl-expressing AML cells. This Gas6-Axl paracrine axis between AML cells and BMDSCs establishes a chemoprotective tumor cell niche that can be abrogated by Axl-targeting approaches. Axl inhibition is active in FLT3-mutated and FLT3 wild-type AML, improves clinically relevant end points, and its efficacy depends on presence of Gas6 and Axl. Axl inhibition alone or in combination with chemotherapy might represent a novel therapeutic avenue for AML.

Circulating tumor cells (CTCs) were introduced as biomarkers more than 10 years ago, but capture of viable CTCs at high purity from peripheral blood of cancer patients is still a major technical challenge. Here, we report a novel microfluidic platform designed for marker independent capture of CTCs. The Parsortix™ cell separation system provides size and deformability-based enrichment with automated staining for cell identification, and subsequent recovery (harvesting) of cells from the device. Using the Parsortix™ system, average cell capture inside the device ranged between 42% and 70%. Subsequent harvest of cells from the device ranged between 54% and 69% of cells captured. Most importantly, 99% of the isolated tumor cells were viable after processing in spiking experiments as well as after harvesting from patient samples and still functional for downstream molecular analysis as demonstrated by mRNA characterization and array-based comparative genomic hybridization. Analyzing clinical blood samples from metastatic (n = 20) and nonmetastatic (n = 6) cancer patients in parallel with CellSearch(®) system, we found that there was no statistically significant difference between the quantitative behavior of the two systems in this set of twenty six paired separations. In conclusion, the epitope independent Parsortix™ system enables the isolation of viable CTCs at a very high purity. Using this system, viable tumor cells are easily accessible and ready for molecular and functional analysis. The system's ability for enumeration and molecular characterization of EpCAM-negative CTCs will help to broaden research into the mechanisms of cancer as well as facilitating the use of CTCs as "liquid biopsies."

It is well-known that sex hormones can directly and indirectly influence immune cell function. Different studies support a suppressive role of androgens on different components of the immune system by decreasing antibody production, T cell proliferation, NK cytotoxicity, and stimulating the production of anti-inflammatory cytokines. Androgen receptors have also been detected in many different cells of hematopoietic origin leading to direct effects of their ligands on the development and function of the immune system. The immunosuppressive properties of androgens could contribute to gender dimorphisms in autoimmune and infectious disease and thereby also hamper immune surveillance of tumors. Consistently, females generally are more prone to autoimmunity, while relatively less susceptible to infections, and have lower incidence and mortality of the majority of cancers compared to males. Some studies show that androgen deprivation therapy (ADT) can induce expansion of naïve T cells and increase T-cell responses. Emerging clinical data also reveal that ADT might enhance the efficacy of various immunotherapies including immune checkpoint blockade. In this review, we will discuss the potential role of androgens and their receptors in the immune responses in the context of different diseases. A particular focus will be on cancer, highlighting the effect of androgens on immune surveillance, tumor biology and on the efficacy of anti-cancer therapies including emerging immune therapies.

Circulating tumor cells (CTCs) hold great potential to answer key questions of how non-small cell lung cancer (NSCLC) evolves and develops resistance upon anti-PD-1/PD-L1 treatment. Currently, their clinical utility in NSCLC is compromised by a low detection rate with the established, Food and Drug Administration (FDA)-approved, EpCAM-based CellSearch® System. We tested an epitope-independent method (ParsortixTM system) and utilized it to assess PD-L1 expression of CTCs from NSCLC patients. We prospectively collected 127 samples, 97 of which were analyzed with the epitope-independent system in comparison to the CellSearch system. CTCs were determined by immunocytochemistry as intact, nucleated, CD45−, pankeratins (K)+ cells. PD-L1 status of CTCs was evaluated from 89 samples. With the epitope-independent system, ≥1 CTC per blood sample was detected in 59 samples (61%) compared to 31 samples (32%) with the EpCAM-based system. Upon PD-L1 staining, 47% of patients harbored only PD-L1+CTCs, 47% had PD-L1+ and PD-L1−CTCs, and only 7% displayed exclusively PD-L1−CTCs. The percentage of PD-L1+CTCs did not correlate with the percentage of PD-L1+ in biopsies determined by immunohistochemistry (p = 0.179). Upon disease progression, all patients showed an increase in PD-L1+CTCs, while no change or a decrease in PD-L1+CTCs was observed in responding patients (n = 11; p = 0.001). Our data show a considerable heterogeneity in the PD-L1 status of CTCs from NSCLC patients. An increase of PD-L1+CTCs holds potential to predict resistance to PD-1/PD-L1 inhibitors.

PURPOSE The open-label, phase III EVOKE-01 study evaluated sacituzumab govitecan (SG) versus standard-of-care docetaxel in metastatic non–small cell lung cancer (mNSCLC) with progression on/after platinum-based chemotherapy, anti–PD-(L)1, and targeted treatment for actionable genomic alterations (AGAs). Primary analysis is reported. METHODS Patients were randomly assigned 1:1 (stratified by histology, best response to last anti–PD-(L)1–containing regimen, and AGA treatment received or not) to SG (one 10 mg/kg intravenous infusion on days 1 and 8) or docetaxel (one 75 mg/m 2 intravenous infusion on day 1) in 21-day cycles. Primary end point was overall survival (OS). Key secondary end points were investigator-assessed progression-free survival (PFS), objective response rate, patient-reported symptom assessment, and safety. RESULTS In the intention-to-treat population (SG, n = 299; docetaxel, n = 304), 55.4% had one previous line of therapy. Median follow-up was 12.7 months (range, 6.0-24.0). The primary end point was not met. There was a numerical OS improvement for SG versus docetaxel (median, 11.1 v 9.8 months; hazard ratio [HR], 0.84 [95% CI, 0.68 to 1.04]; one-sided P = .0534), consistent across squamous and nonsquamous histologies. Median PFS was 4.1 versus 3.9 months (HR, 0.92 [95% CI, 0.77 to 1.11]). An OS benefit was observed for SG (n = 192) versus docetaxel (n = 191) in mNSCLC nonresponsive to last anti–PD-(L)1–containing regimen (3.5-month median OS increase; HR, 0.75 [95% CI, 0.58 to 0.97]); this was consistent across histologies. Among patients receiving SG and docetaxel, 6.8% and 14.2% discontinued because of treatment-related adverse events (TRAEs), respectively; 1.4% and 1.0%, respectively, had TRAEs leading to death. CONCLUSION Although statistical significance was not met, OS numerically improved with SG versus docetaxel, which was consistent across histologies. Clinically meaningful improvement in OS was noted in mNSCLC nonresponsive to last anti–PD-(L)1–containing regimen. SG was better tolerated than docetaxel and consistent with its known safety profile, with no new safety signals.