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Antibody–drug conjugates (ADCs) is a fast moving class of targeted biotherapeutics that currently combines the selectivity of monoclonal antibodies with the potency of a payload consisting of cytotoxic agents. For many years microtubule targeting and DNA-intercalating agents were at the forefront of ADC development. The recent approval and clinical success of trastuzumab deruxtecan (Enhertu ® ) and sacituzumab govitecan (Trodelvy ® ), two topoisomerase 1 inhibitor-based ADCs, has shown the potential of conjugating unconventional payloads with differentiated mechanisms of action. Among future developments in the ADC field, payload diversification is expected to play a key role as illustrated by a growing number of preclinical and clinical stage unconventional payload-conjugated ADCs. This review presents a comprehensive overview of validated, forgotten and newly developed payloads with different mechanisms of action.

Nodal cytotoxic molecule (CM)‐positive peripheral T‐cell lymphoma (CTL) has recently been recognized as a clinicopathologically distinct disease. To further characterize this disease, here we compared 58 patients with Epstein‐Barr virus (EBV)‐negative CTL to 48 patients with EBV‐positive CTL. The two groups did not differ in histopathology, T‐cell receptor (TCR) expression or rearrangement incidences, or survival curves. However, patients with EBV‐negative CTL less frequently showed hepatic involvement (P = .007), B symptoms (P = .020), hemophagocytosis (P = .024), and detectable CD4 (P = .002) and CD5 (P = .009). Univariate and multivariate analyses identified three factors that independently predicted favorable survival, onset age <60 years (P = .002), CD5 expression (P = .002), and mixed morphology (P = .013), TCRαβ was not an independent predictor (P = .30), but was strongly linked with long survivorship among patients younger than 60 years old. A prognostic model incorporating these factors worked well for prognostic delineation, independently of the International Prognostic Index (P = .007 vs P = .082) and Prognostic Index for PTCL (P = .020 vs P = .15). Moreover, this constellation of findings indicated two nodal indolent diseases: CD5+TCRαβ (n = 13), and CD5+ NK‐cell type lacking TCR expression or clonal TCRγ rearrangement (n = 4). The survival curves for these two groups were significantly superior to others (n = 29, P < .001). These diseases appear to be unique in their indolent clinical behavior, and should be managed differently from other diseases. This retrospective study revealed that nodal EBV‐negative CTL is heterogeneous, and there may be prognostically indolent subgroups defined by immunophenotype and genotype—ie, CD5+ TCRαβ and CD5+ NK‐cell types—which have not previously been highlighted.

Peripheral T‐ or natural killer (NK)‐cell lymphomas are rare and difficult‐to‐recognize diseases. It remains arduous to distinguish between NK cell‐ and cytotoxic T‐lymphocyte‐derived lymphomas through routine histological evaluation. To clarify the cells of origin, we focused on NK‐cell receptors and examined the expression using immunohistochemistry in 22 cases with T‐ and NK‐cell neoplasms comprising angioimmunoblastic T‐cell lymphoma, anaplastic lymphoma kinase (ALK)‐positive and ‐negative anaplastic large‐cell lymphomas, extranodal NK/T‐cell lymphoma, nasal type, monomorphic epitheliotropic intestinal T‐cell lymphoma, aggressive NK‐cell leukemia, and other peripheral T‐cell lymphomas. Inhibitory receptor leukocyte immunoglobulin‐like receptor subfamily B member 1 (LILRB1) was detected in 14 (64%) cases, whereas activating receptors DNAM1, NKp46, and NKG2D were expressed in 7 (32%), 9 (41%), and 5 (23%) cases, respectively. Although LILRB1 was detected regardless of the disease entity, the activating NK‐cell receptors were expressed predominantly in TIA‐1‐positive neoplasms (DNAM1, 49%; NKp46, 69%; and NKG2D, 38%). In addition, NKp46 and NKG2D were detected only in NK‐cell neoplasms and cytotoxic T‐lymphocyte‐derived lymphomas including monomorphic epitheliotropic intestinal T‐cell lymphoma. One Epstein‐Barr virus‐harboring cytotoxic T‐lymphocyte‐derived lymphoma mimicking extranodal NK/T‐cell lymphoma, nasal type lacked these NK‐cell receptors, indicating different cell origin from NK and innate‐like T cells. Furthermore, NKG2D expression showed a negative impact on survival among the 22 examined cases, which mainly received the standard chemotherapy regimen (log‐rank test, P = .024). We propose that the presence of activating NK‐cell receptors may provide new insights into understanding peripheral T‐cell lymphomas and characterizing them as innate‐like T‐cell neoplasm. It remains difficult to distinguish between NK‐cell‐ and cytotoxic T‐lymphocyte‐derived lymphomas through routine histological evaluation. Cytotoxic T‐lymphocyte‐derived lymphomas are characterized as innate‐like T‐cell neoplasms by the expression of activating NK‐cell receptors. NKG2D expression might show a negative impact on survival in T‐ and NK‐cell lymphoma cases receiving the standard CHOP‐like regimen.

SummaryPurpose Among alkaloids, abundant secondary metabolites in plants, aporphines constitute a class of compounds with interesting biological activities, including anticancer effects. The present study evaluated the anticancer activities of 14 substances, including four aporphine derivatives acquired through the biomonitoring of (±)-apomorphine hydrochloride total synthesis from 2-phenethylamine and 3,4-dimethoxybenzaldehyde against head and neck squamous cell carcinoma (HNSCC). Methods The cytotoxic effects of compounds against a panel of HNSCC cell lines were determined by PrestoBlue cell viability assay, while the genotoxicity of substances was evaluated by micronucleus test. Cell death was detected by flow cytometry (Annexin V/7AAD) and western blot analysis was used to detect the presence of cleaved Caspase-3 molecules. Results The aporphine and isoquinoline derivatives APO, C1, and A5 significantly reduced HNSCC cell viability and promoted DNA damages in these cells. Further, by activating the Caspase-3 pathway, these substances were able to induce apoptosis. Conclusion Our results revealed that APO, C1, and A5 exhibit cytotoxic effects in HNSCC cells. The mechanisms of action appear to be partly via the generation of DNA damages and apoptosis induction through Caspase-3 pathway activation. This study provides preclinical data that suggest a potential therapeutic role for APO, C1, and A5 against head and neck cancer cells.

The current World Health Organization (WHO) classification includes two types of natural killer (NK)-cell lymphomas: extranodal NK/T-cell lymphoma, nasal type (ENKL), and aggressive NK-cell leukemia (ANKL). These diseases are mostly endemic to East Asia and Latin America. The Epstein–Barr virus (EBV) is usually detected in tumor cells, suggesting that EBV plays an important role in lymphomagenesis. At the site of origin, ENKL can be divided into two major subtypes: nasal and extranasal diseases. The advanced disease presentation, highly aggressive clinical course, and poor prognosis of the latter are analogous to ANKL. It is well known that P-glycoprotein, which is a product of the multi-drug resistance ( MDR1 ) gene, is expressed on neoplastic cells of ENKL or ANKL. This is a major cause of the refractoriness of malignant lymphoma to conventional chemotherapeutic regimens containing anthracycline. Recent studies, however, have identified that L-asparaginase-containing regimens, such as SMILE (steroid, methotrexate, ifosfamide, L-asparaginase and etoposide), are effective for ENKL. Considering the myelotoxicity of SMILE, its use in the treatment of ANKL needs some modifications, but this treatment scheme is promising in improving the prognosis of NK-cell lymphomas.

Natural killer (NK) cells are a potent innate source of cytokines and cytoplasmic granules. Their effector functions are tightly synchronized by the balance between the stimulatory and inhibitory receptors. Here, we quantified the proportion of NK cells and the surface presence of Galectin-9 (Gal-9) from the bone marrow, blood, liver, spleen, and lungs of adult and neonatal mice. We also examined the effector functions of Gal-9 + NK cells compared with their Gal-9 - counterparts. Our results revealed that Gal-9 + NK cells are more abundant in tissues, in particular, in the liver than in the blood and bone marrow. We found Gal-9 presence was associated with enhanced cytotoxic effector molecules granzyme B (GzmB) and perforin expression. Likewise, Gal-9 expressing NK cells displayed greater IFN-γ and TNF-α expression than their negative counterparts under hemostatic circumstances. Notably, the expansion of Gal-9 + NK cells in the spleen of mice infected with E. coli implies that Gal-9 + NK cells may provide a protective role against infection. Similarly, we found the expansion of Gal-9 + NK cells in the spleen and tumor tissues of melanoma B16-F10 mice. Mechanistically, our results revealed the interaction of Gal-9 with CD44 as noted by their co-expression/co-localization. Subsequently, this interaction resulted in enhanced expression of Phospho-LCK, ERK, Akt, MAPK, and mTOR in NK cells. Moreover, we found Gal-9 + NK cells exhibited an activated phenotype as evidenced by increased CD69, CD25, and Sca-1 but reduced KLRG1 expression. Likewise, we found Gal-9 preferentially interacts with CD44 high in human NK cells. Despite this interaction, we noted a dichotomy in terms of effector functions in NK cells from COVID-19 patients. We observed that the presence of Gal-9 on NK cells resulted in a greater IFN-γ expression without any changes in cytolytic molecule expression in these patients. These observations suggest differences in Gal-9 + NK cell effector functions between mice and humans that should be considered in different physiological and pathological conditions. Therefore, our results highlight the important role of Gal-9 via CD44 in NK cell activation, which suggests Gal-9 is a potential new avenue for the development of therapeutic approaches to modulate NK cell effector functions.

COVID-19 has caused more than 7 million deaths worldwide, and according to the World Health Organization, it continues to result in more than 1000 reported deaths per month at the time of this writing. It is crucial to understand the immune response to COVID-19 since the virus continues to persist. Natural killer (NK) cells play a critical role in the immune defense against viral infections, including COVID-19. While it is well documented that infected patients have a reduction in lymphocytes and NK cells, gaps in knowledge exist regarding the function of NK cells. To study the function of NK cells in patients hospitalized with COVID-19, peripheral blood was obtained from patients admitted to the medical (non-ICU) wards at a large tertiary hospital. We demonstrated a decrease in the mature cytotoxic subset of NK cells within the peripheral blood of patients hospitalized with COVID-19. We also observed a notable reduction in the cytotoxic function of NK cells against tumor targets. We examined the mechanisms leading to NK cell killing. We found reductions in the intracellular levels of effector molecules, the degranulation of cytotoxic granules, and the extracellular concentrations of released effector molecules. We identified dysfunctional intracellular granule trafficking required to position the granules for degranulation, which would be consistent with the reduced release of effector molecules. We found clusters of inhibitory receptors were upregulated in subsets of NK cells, in keeping with inhibition of cytotoxicity. Additionally, males with COVID-19 showed NK cell defects compared to healthy males, while no significant differences were observed in females. Our findings highlight defects in cytolytic effector molecules, granule trafficking and release, and increased expression of inhibitory receptors on NK cells in patients hospitalized with COVID-19, in addition to a sex difference in cytolytic function, which contributes to defective NK cell function in COVID-19.

Peripheral T cell lymphoma not otherwise specified (PTCL-N) and ALK-negative anaplastic large cell lymphoma (ALCL) are heterogeneous categories with poor diagnostic reproducibility. To clarify the biologic features of these categories, we investigated the expression of two chemokine receptors, type 1 (Th1/Tc1)-associated CXCR3 and type 2 (Th2/Tc2)-associated CCR4 in 110 PTCL-N and 35 ALK-negative ALCL cases, as well as the expression of cytotoxic molecules (CM). CXCR3 and CCR4 were expressed in 69 (63%) and 37 (34%) of PTCL-N, and in 12 (34%) and 6 (17%) of ALK-negative ALCL, respectively. In PTCL-N, type 1 pattern (CXCR3 + CCR4 − ) was dominant (52%), whereas in ALK-negative ALCL, 54% were negative for both ( P  < 0.0001). CM was expressed in 38% of PTCL-N and 51% of ALK-negative ALCL. CM-positive PTCL-N consisted mostly of type 1 disease, which shows type 1 phenotype. In contrast, type 2 pattern (CXCR3 − CCR4 + ) was recognized in the CM-negative group only. Among type 1 disease, CM-positive cases had a higher female ratio and more aggressive clinical features than CM-negative cases and a poorer prognosis ( P  = 0.006). Multivariate analysis confirmed that the type 1 phenotype with CM expression was an independent prognostic factor. In both PTCL-N and ALK-negative ALCL, CM-positive type 1 disease had an extremely poor prognosis.

The present study was carried out to investigate the effects of microsporidial infection on redox regulation mechanism and oxidative stress in tasar silkworm Antheraea mylitta. High level of superoxide radical (p < 0.05), nitric oxide (p < 0.001) and lipid peroxidation (p < 0.001) was observed in haemolymph of pebrinised larvae, which indicated the resultant generation of cytotoxic molecules and oxidative damage. Increased phenol oxidase (PO) activity in haemolymph of pebrinised larvae indicated the activation of immune defences during pathological conditions. In addition, higher level of glutathione-S-tranferase (GST) activity and reduced glutathione (GSH) level observed in pebrinised larvae indicated adaptive behaviour of tissue against toxic oxyradicals (p < 0.05). Conversely, low level of ascorbic acid (ASA) content suggested that the larvae might have used these compounds to counteract stress in tissues or low uptake under microspridial infection (p < 0.05). Present findings provide new insights into the cellular and biochemical bases of host-pathogen interactions in tasar silkworm A. mylitta.

A 67-year-old woman presented with a swelling on both sides of the neck. Biopsy of an enlarged cervical lymph node on the left side and flow cytometric analysis revealed CD56-positive CD4 + CD8 + abnormal NK/T cells. A Southern blot analysis of the cervical lymph node biopsy specimen showed a human T-cell leukemia virus type 1 provirus DNA monoclonal band. Based on these findings, the patient was diagnosed with CD56-positive adult T-cell leukemia/lymphoma. After five cycles of cyclophosphamide, doxorubicin, vincristine, and prednisone therapy, the general condition of the patient gradually declined, indicating resistance to treatment, and approximately 9 months after the onset of symptoms, the patient died. CD56 is recognized as an unfavorable prognostic marker in cases of acute myeloid leukemia with t(8;21), acute promyelocytic leukemia, and anaplastic large cell lymphoma. Only eight cases of CD56-positive adult T-cell leukemia/lymphoma have been reported so far in the literature. Most of these cases were in the advanced stage at diagnosis and had poor outcomes. It appears that the correlation between CD56 expression and outcomes in patients with adult T-cell leukemia/lymphoma should be clarified by investigating a larger number of cases in the future.