Single-cell CAR T atlas reveals type 2 function in 8-year leukaemia remission.

Despite a high response rate in chimeric antigen receptor (CAR) T cell therapy for acute lymphocytic leukaemia (ALL)1-3, approximately 50% of patients relapse within the first year4-6, representing an urgent question to address in the next stage of cellular immunotherapy. Here, to investigate the molecular determinants of ultralong CAR T cell persistence, we obtained a single-cell multi-omics atlas from 695,819 pre-infusion CAR T cells at the basal level or after CAR-specific stimulation from 82 paediatric patients with ALL enrolled in the first two CAR T ALL clinical trials and 6 healthy donors. We identified that elevated type 2 functionality in CAR T infusion products is significantly associated with patients maintaining a median B cell aplasia duration of 8.4 years. Analysis of ligand-receptor interactions revealed that type 2 cells regulate a dysfunctional subset to maintain whole-population homeostasis, and the addition of IL-4 during antigen-specific activation alleviates CAR T cell dysfunction while enhancing fitness at both transcriptomic and epigenomic levels. Serial proteomic profiling of sera after treatment revealed a higher level of circulating type 2 cytokines in 5-year or 8-year relapse-free responders. In a leukaemic mouse model, type 2high CAR T cell products demonstrated superior expansion and antitumour activity, particularly after leukaemia rechallenge. Restoring antitumour efficacy in type 2low CAR T cells was attainable by enhancing their type 2 functionality, either through incorporating IL-4 into the manufacturing process or by priming manufactured CAR T products with IL-4 before infusion. Our findings provide insights into the mediators of durable CAR T therapy response and suggest potential therapeutic strategies to sustain long-term remission by boosting type 2 functionality in CAR T cells.

Prevalence of antenatal depression and postpartum depression among Chinese fathers: A systematic review and meta-analysis.

Background: Paternal antenatal depression and postpartum depression are associated with adverse health outcomes in mothers and infants; however, their prevalence among Chinese fathers remains controversial. This meta-analysis aimed to summarize the prevalence of antenatal depression and postpartum depression in Chinese fathers. Methods: We conducted a systematic meta-analysis on the prevalence of antenatal depression and postpartum depression among Chinese fathers by searching 11 databases. Pooled estimates and 95 % confidence intervals were calculated. The choice between a random-effects model and a fixed-effects model was based on an assessment of heterogeneity among the studies as well as assumptions regarding the similarity of the studies in terms of clinical characteristics, quality, design, and conduct. Subgroup and meta-regression analyses were conducted based on the scale used to measure antenatal depression and postpartum depression, the region where the study was completed, the time of the study, the study design, the number of children, publication language, the study site, and quality assessment. Results: This meta-analysis included 28 studies with 8795 participants. The prevalence of antenatal depression among Chinese fathers was 11 % (95 % CI: 5%-17 %, P < 0.01) using a random-effects model. Heterogeneity was I2 = 91 %. Publication language moderated the prevalence of paternal antenatal depression (the amount of heterogeneity accounted for was 92.13 %). The prevalence of postpartum depression among Chinese fathers was 16 % (95 % CI: 13%-18 %, P < 0.01), using a random-effects model. The heterogeneity was I2 = 94 %. The prevalence of paternal postpartum depression was moderated by the scale used to measure postpartum depression (39.17 % heterogeneity) and the region where the study was completed (33.15 % heterogeneity). Moreover, Egger's test (t = 4.542, P < 0.001) indicated publication bias in studies on postpartum depression among Chinese fathers. However, after applying the trimming correction, the pooled prevalence of postpartum depression had a P value of <0.05, indicating that despite the publication bias, the results remain reliable and unaffected in terms of effect size. Conclusion: The prevalence of antenatal depression and postpartum depression among Chinese fathers was similar to those reported in low- and middle-income countries. Fathers should receive regular screening, effective prevention, and appropriate treatment. However, interpreting these results requires consideration of the limitations of the study.

Assessing the global burden of mesothelioma: trends, socioeconomic influences, and asbestos exposure: a retrospective cohort study.

INTRODUCTION: Mesothelioma is an uncommon type of cancer which has received little attention. This study aims to evaluate the global disease burden; trends of mesothelioma by age, sex, and geographic locations; and its risk factors on the population level. METHODS: The Global Cancer Observatory in 2022 and 2019 Global Burden of Disease were accessed for mesothelioma incidence and its risk factors worldwide. Multivariable linear regression analyses was conducted to explore the associations between mesothelioma incidence and key predictors including Human Development Index (HDI), Gross Domestic Product (GDP) per capita, and occupational asbestos exposure, adjusting for age and sex across global regions. RESULTS: This study identified 30,870 global cases of mesothelioma in 2022, with a higher age-standardized incidence rate (ASR) in males (0.25 per 100,000) compared to females (0.39 per 100,000). Geographical analysis indicated the highest disease burden in Northern Europe, with particular prevalence in more developed regions. The incidence was also significantly associated with higher Human Development Index (HDI), with a beta coefficient of 0.133 overall, and Gross Domestic Product (GDP) per capita, with a beta coefficient of 0.101. These socioeconomic factors exhibited stronger associations in the elderly population, especially with HDI (ß=0.512) and GDP (ß=0.389), than in adults. Additionally, occupational exposure to asbestos remained a significant risk factor across all groups, except for the younger adult population, with an overall beta of 0.122 for incidence. The temporal trend analysis revealed a general decrease in mesothelioma incidence, particularly in the 15-49 years age group. CONCLUSIONS: The analysis indicates a higher mesothelioma incidence in males and in developed regions, with marked disparities noted particularly in Northern Europe. Significant correlations with socioeconomic indicators-HDI and GDP-and occupational asbestos exposure were identified, particularly affecting the elderly. Despite a decline in global incidence, especially among younger individuals, persistent cases in females highlight the need for continued public health measures addressing both occupational and environmental exposures.

FAM122A ensures cell cycle interphase progression and checkpoint control by inhibiting B55α/PP2A through helical motifs.

The Ser/Thr protein phosphatase 2 A (PP2A) regulates the dephosphorylation of many phosphoproteins. Substrate recognition are mediated by B regulatory subunits. Here, we report the identification of a substrate conserved motif [RK]-V-x-x-[VI]-R in FAM122A, an inhibitor of B55α/PP2A. This motif is necessary for FAM122A binding to B55α, and computational structure prediction suggests the motif, which is helical, blocks substrate docking to the same site. In this model, FAM122A also spatially constrains substrate access by occluding the catalytic subunit. Consistently, FAM122A functions as a competitive inhibitor as it prevents substrate binding and dephosphorylation of CDK substrates by B55α/PP2A in cell lysates. FAM122A deficiency in human cell lines reduces the proliferation rate, cell cycle progression, and hinders G1/S and intra-S phase cell cycle checkpoints. FAM122A-KO in HEK293 cells attenuates CHK1 and CHK2 activation in response to replication stress. Overall, these data strongly suggest that FAM122A is a short helical motif (SHeM)-dependent, substrate-competitive inhibitor of B55α/PP2A that suppresses multiple functions of B55α in the DNA damage response and in timely progression through the cell cycle interphase.

Impact of lymph node dissection on cancer-specific survival in non-small cell lung cancer patients: a SEER database analysis.

Background: Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related mortality worldwide, and lymph node dissection (LND) is a significant surgical procedure employed in its management. Although some studies suggest benefits of LND, the extent of its impact on survival, the optimal range of lymph nodes to be examined, and the specific patient groups that benefit most remain areas of active debate and investigation. Methods: A population-based analysis was conducted using the Surveillance, Epidemiology, and End Results (SEER) database. Patients diagnosed with NSCLC between 2004 and 2017, undergoing primary tumor resection, were included. Descriptive, univariate, and multivariate analyses assessed the effect of LND on survival, and a restricted cubic spline method determined the optimal range for lymph node examination. Results: This study of 37,323 NSCLC patients delved into the impact of LND on lung cancer-specific survival. Key findings revealed a median survival of 19.58 months, with 85% mortality. Baseline characteristics included a majority of White patients (81%), distant stage diagnoses (63%), and 64% with Grade IV tumors. LND emerged as a crucial predictor, influencing survival across age, gender, race, and tumor characteristics. Univariate analysis highlighted its significance, with higher T, N, and M categories, advanced stage, and poorer grade associating with elevated hazard ratios. Multivariate Cox proportional hazards (PH) analysis reinforced LND's impact, showcasing lower hazard ratios post-removal. Hazard ratios for biopsy/aspiration and removal of regional lymph nodes were 0.85 [95% confidence interval (CI): 0.81-0.89; P<0.001] and 0.43 (95% CI: 0.39-0.46; P<0.001), underscoring the protective effect. Visualizations and a U-shaped curve analysis identified an optimal range (24-32 nodes) for examination, emphasizing the nuanced benefits across NSCLC stages. Conclusions: The study findings suggest that LND plays a critical role in improving cancer-specific survival in NSCLC patients, particularly when tailored to the early stages of the disease. The optimal range of lymph nodes examined, between 24 and 32, offers crucial insights for personalized NSCLC treatment strategies and may enhance overall survival. These results underscore the need for refined surgical guidelines that incorporate the extent of LND, supporting the utility of a more personalized approach in NSCLC management.

Circular RNA sirtuin-1 restrains the malignant phenotype of non-small cell lung cancer cells via the microRNA-510-5p/SMAD family member 7 axis.

Circular RNA (circRNA) sirtuin-1 (SIRT1) is differentially expressed in non-small cell lung cancer (NSCLC), but its specific mechanism is still uncertain. The study was to figure out the latent molecular mechanism of circSIRT1 in NSCLC. The results clarified that circSIRT1 and SMAD family member 7 (SMAD7) were downregulated, but microRNA (miR)-510-5p was upregulated in NSCLC. CircSIRT1 expression was linked with tumor-node-metastasis staging and tumor size in NSCLC patients. Elevating circSIRT1 or suppressing miR-510-5p refrained NSCLC cell activities and glycolysis and inactivated the wnt/ß-catenin pathway, while knockdown of circSIRT1 promoted the malignant behavior of NSCLC cells. Besides, inhibition of malignant behavior in NSCLC cells by elevating circSIRT1 was reversed by knockdown of SMDA7. circSIRT1 bound to miR-510-5p to target SMAD7. In short, circSIRT1 represses NSCLC cell malignant development via miR-510-5p to target SMAD7, making it a latent target for NSCLC treatment.

Effects of clinical medications on male fertility and prospects for stem cell therapy.

An increasing number of men require long-term drug therapy for various diseases. However, the effects of long-term drug therapy on male fertility are often not well evaluated in clinical practice. Meanwhile, the development of stem cell therapy and exosomes treatment methods may provide a new sight on treating male infertility. This article reviews the influence and mechanism of small molecule medications on male fertility, as well as progress of stem cell and exosomes therapy for male infertility with the purpose on providing suggestions (recommendations) for evaluating the effect of drugs on male fertility (both positive and negative effect on male fertility) in clinical application and providing strategies for diagnosis and treatment of male infertility.

Effectiveness of probiotic/prebiotic/synbiotic treatments on anxiety: A systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: Anxiety can adversely affect human well-being. This meta-analysis aimed to evaluate the effects of interventions that alter the gut microbes (including probiotics, prebiotics, and synbiotics) on anxiety. METHODS: A systematic meta-analysis of the effects of probiotics, prebiotics, and synbiotics on anxiety was conducted by searching randomized controlled trials (RCTs) in 13 databases. The primary outcomes were the pre- and post-intervention anxiety scores in the intervention and placebo groups. Anxiety scores were extracted as standard mean differences (SMDs) and pooled based on a random effects model. Subgroup analyses of anxiety scales, health status, gastrointestinal symptoms, flora strains, treatment type, probiotic dose, region, and treatment duration were also performed. RESULTS: 29 RCTs (2035 participants) were included, revealing that both probiotics and synbiotics significantly reduced anxiety scores. Additionally, anxiety scores did not significantly reduce when comparing prebiotics and placebos. LIMITATIONS: Owing to the small combined effect size of probiotic/prebiotic/synbiotic treatments and the relatively few studies on prebiotics and synbiotics included in the analysis, the findings of probiotic/prebiotic/synbiotic treatments are preliminary. CONCLUSIONS: Our study indicated that probiotics and synbiotics can reduce anxiety scores; however, it might be premature to conclude their clinical efficacy in alleviating anxiety due to the small effect size. There is no consensus regarding the optimal dose, treatment duration, treatment type, or probiotic strain to improve anxiety. Moreover, the mechanisms by which probiotics and synbiotics improve anxiety remain unclear. More RCTs are needed to determine the mechanisms of action and to identify appropriate markers to clarify their effects.

Ripple phenomenon and artifact elimination in millimeter-wave imaging of a hidden target.

In millimeter-wave imaging of a hidden target, the effect of the dielectric cover before the target is typically ignored. This results in ripple-corrupted images that pose challenges for target recognition. In this paper, we provide a perspective for understanding the image of the hidden target, which clearly reveals the origin of the ripples, and propose a separation method that not only gets rid of ripples, but also obtains the target's depth map. Reflections and transmissions during imaging are considered and decoupled to separately form images corresponding to each real or virtual object. An algorithm based on the range-direction spread function is developed to iteratively estimate the depth and reflectivity of the target. Imaging experiments with and without a cover are conducted to demonstrate the formation and influence of ripples and to verify the proposed algorithm. Our work deepens the comprehension of covered target imaging. Benefited fields might include non-destructive testing, through-wall imaging, subsurface imaging, and security screening.

Challenges and opportunities of CAR T-cell therapies for CLL.

Chimeric antigen receptor (CAR) T-cell therapies have transformed the treatment landscape of blood cancers. These engineered receptors which endow T cells with antibody-like target cell recognition combined with the typical T cell target cell lysis abilities. Introduced into the clinic in the 2010s, CAR T-cells have shown efficacy in chronic B lymphocytic leukemia (CLL), but a majority of patients do not achieve sustained remission. Here we discuss the current treatment landscape in CLL using small molecules and allogeneic stem cell transplantation, the niche CAR T-cells filled in this context, and what we have learned from biomarker and mechanistic studies. Several product parameters and improvements are introduced as examples of how the bedside-to-bench is translated into improved CAR T-cells for CLL. We hope to convey to our readers the crucial role translational medicine plays in transforming the treatment outcomes for patients with CLL and how this line of research is an essential component of modern medicine.

PKC-ζ mediated reduction of the extracellular vesicles-associated TGF-ß1 overcomes radiotherapy resistance in breast cancer.

BACKGROUND: Radiotherapy is widely applied in breast cancer treatment, while radiotherapy resistance is inevitable. TGF-ß1 has been considered to be an endogenous factor for the development of radiotherapy resistance. As a large portion of TGF-ß1 is secreted in an extracellular vesicles-associated form (TGF-ß1EV), particularly in radiated tumors. Thus, the understanding of the regulation mechanisms and the immunosuppressive functions of TGF-ß1EV will pave a way for overcoming the radiotherapy resistance in cancer treatment. METHODS: The superoxide-Zinc-PKC-ζ-TGF-ß1EV pathway in breast cancer cells was identified through sequence alignments of different PKC isoforms, speculation and experimental confirmation. A series of functional and molecular studies were performed by quantitative real-time PCR, western blot and flow cytometry analysis. Mice survival and tumor growth were recorded. Student's t test or two-way ANOVA with correction was used for comparisons of groups. RESULTS: The radiotherapy resulted in an increased expression of the intratumoral TGF-ß1 and an enhanced infiltration of the Tregs in the breast cancer tissues. The intratumoral TGF-ß1 was found mainly in the extracellular vesicles associated form both in the murine breast cancer model and in the human lung cancer tissues. Furthermore, radiation induced more TGF-ß1EV secretion and higher percentage of Tregs by promoting the expression and phosphorylation of protein kinase C zeta (PKC-ζ). Importantly, we found that naringenin rather than 1D11 significantly improved radiotherapy efficacy with less side effects. Distinct from TGF-ß1 neutralizing antibody 1D11, the mechanism of naringenin was to downregulate the radiation-activated superoxide-Zinc-PKC-ζ-TGF-ß1EV pathway. CONCLUSIONS: The superoxide-zinc-PKC-ζ-TGF-ß1EV release pathway was elucidated to induce the accumulation of Tregs, resulting in radiotherapy resistance in the TME. Therefore, targeting PKC-ζ to counteract TGF-ß1EV function could represent a novel strategy to overcome radiotherapy resistance in the treatment of breast cancer or other cancers. TRIAL REGISTRATION: The using of patient tissues with malignant Non-Small Cell Lung Cancer (NSCLC) was approved by the ethics committees at Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China (NCC2022C-702, from June 8th, 2022).

Prognostic significance of eighth edition TNM stage criteria in combined small-cell lung cancer.

Objectives: This study aimed to evaluate the prognostic significance of the eighth edition TNM stage criteria in patients with combined small-cell lung cancer (C-SCLC) on a population level. Methods: Using the Surveillance, Epidemiology, and End Results (SEER) database, patients diagnosed with C-SCLC (histology code 8245) between the years 2004 and 2015 were identified. We performed a Kaplan-Meier analysis and used the multivariable cox regression proportional hazards model to obtain prognostic overall survival estimates for each group of patients. Results: A total of 477 patients diagnosed with C-SCLC were identified. The T, N, M, TNM, and combined TNM stage status of the eighth edition were all significant prognostic factors for patients' overall survivals, with the best discrimination identified in the combined stages. Surgery was also found to be a prognostic factor (HR =1.95, 95%CI =1.49-2.56, p<0.01) for patients with C-SCLC. Conclusions: The combined eighth edition of the TNM staging criteria shows reliable prognostic significance in patients with C-SCLC. Moreover, surgery might be significant for improving the patients' prognosis.

FAM122A ensures cell cycle interphase progression and checkpoint control as a SLiM-dependent substrate-competitive inhibitor to the B55⍺/PP2A phosphatase.

The Ser/Thr protein phosphatase 2A (PP2A) is a highly conserved collection of heterotrimeric holoenzymes responsible for the dephosphorylation of many regulated phosphoproteins. Substrate recognition and the integration of regulatory cues are mediated by B regulatory subunits that are complexed to the catalytic subunit (C) by a scaffold protein (A). PP2A/B55 substrate recruitment was thought to be mediated by charge-charge interactions between the surface of B55α and its substrates. Challenging this view, we recently discovered a conserved SLiM [ RK ]- V -x-x-[ VI ]- R in a range of proteins, including substrates such as the retinoblastoma-related protein p107 and TAU (Fowle et al. eLife 2021;10:e63181). Here we report the identification of this SLiM in FAM122A, an inhibitor of B55α/PP2A. This conserved SLiM is necessary for FAM122A binding to B55α in vitro and in cells. Computational structure prediction with AlphaFold2 predicts an interaction consistent with the mutational and biochemical data and supports a mechanism whereby FAM122A uses the 'SLiM' in the form of a short α-helix to dock to the B55α top groove. In this model, FAM122A spatially constrains substrate access by occluding the catalytic subunit with a second α-helix immediately adjacent to helix 1. Consistently, FAM122A functions as a competitive inhibitor as it prevents binding of substrates in in vitro competition assays and the dephosphorylation of CDK substrates by B55α/PP2A in cell lysates. Ablation of FAM122A in human cell lines reduces the rate of proliferation, progression through cell cycle transitions and abrogates G1/S and intra-S phase cell cycle checkpoints. FAM122A-KO in HEK293 cells results in attenuation of CHK1 and CHK2 activation in response to replication stress. Overall, these data strongly suggest that FAM122A is a 'SLiM'-dependent, substrate-competitive inhibitor of B55α/PP2A that suppresses multiple functions of B55α in the DNA damage response and in timely progression through the cell cycle interphase.

Specific organ metastases and prognosis in lung adenocarcinoma.

OBJECTIVES: This study aims to characterize the specific organ metastatic rates in lung adenocarcinoma (LUAD) patients and identify the prognosis-associated factors. METHODS: Using the Surveillance, Epidemiology and End Results database, 40 117 patients diagnosed with positive histology as the only primary LUAD were included. We stratified patients by diagnosed year, age, sex, race/ethnicity, marital status, insurance, location, TNM stage, organ-specific metastases, surgery, chemotherapy, and radiation therapy. We performed multivariable logistic and Cox regression to identify the factors associated with the presence of specific organ metastases and prognosis predictors. RESULTS: For the 40 117 LUAD patients, 43.69%, 26.25%, 19.66%, 10.60%, and 17.89% had specific organ, bone, brain, liver, and lung metastases, respectively. The average survival in patients with organ metastases was 12.19 months, compared to 36.40 months in patients without metastases. In different kinds of metastatic organ cohorts, the longest average survival was 12.60 months in the lung metastases cohort, and the shortest was 8.43 months in liver metastases cohort. In total, 571 patients with metastases received surgery, which was significantly associated with decreased mortality (hazard ratio 1.82, 95% confidence interval 1.65-2.01, p < 0.01). Patients received surgery of lobectomy or extended (251 of 571, 43.96%) displayed the longest average survival (35.16 months); patients (294 of 571, 51.49%) received sub-lobar resection, had the average survival (19.90 months); patients received local tumor destruction (26 of 571, 4.55%) had the shortest average survival (13.73 months). CONCLUSION: This study provides insights into the specific organ metastatic rates and prognosis in LUAD patients on a population level. These findings suggest that surgery resection should be taken into consideration in the treatment for these LUAD patients.

Monolithic Metamaterial-Integrated Graphene Terahertz Photodetector with Wavelength and Polarization Selectivity.

The frequency spectra and polarization states of terahertz waves can convey significant information about physical interactions and material properties. Compact and miniaturized on-chip platforms for effective capturing of these quantities are being extensively investigated because of their promising potential for paramount applications of terahertz technology such as in situ sensing and characterization. Here, we present a metamaterial-graphene hybrid device that integrates the functions of photodetection, wavelength, and polarization selectivity into a monolithic architecture. Leveraging the ultrahigh design freedom of metamaterial optical properties and the electronically controllable hot-carrier-assisted photothermoelectric effect in graphene, our detector shows resonantly enhanced photoresponse at two specific target wavelengths with orthogonal polarizations. We demonstrate its versatile capabilities for spectrally selective and polarization resolved imaging on a single-chip platform that is free from advanced optical components. Our strategy is beneficial to the future development of multifunctional, compact, and low-cost terahertz sensors.

Adaptable Leukemia Cells Resisting CAR T-cell Attack via B-cell Activation.

Chimeric antigen receptor (CAR) T-cell therapy has achieved remarkable milestones in the treatment of B-cell malignancies. However, cancer cells frequently survive CAR T-cell killing in a large cohort of patients. Relapse oftentimes is associated with antigen loss. In this issue, Im and colleagues report a new mechanism of leukemic-cell resistance to anti-CD19 CAR T cells: Leukemic cells can enable a B-cell activation and germinal center reaction signature, which causes CD19 transcriptional downregulation and survival from CAR exposure. See related article by Im et al., p. 1055 (5).

Single-cell antigen-specific landscape of CAR T infusion product identifies determinants of CD19-positive relapse in patients with ALL.

A notable number of acute lymphoblastic leukemia (ALL) patients develop CD19-positive relapse within 1 year after receiving chimeric antigen receptor (CAR) T cell therapy. It remains unclear if the long-term response is associated with the characteristics of CAR T cells in infusion products, hindering the identification of biomarkers to predict therapeutic outcomes. Here, we present 101,326 single-cell transcriptomes and surface protein landscape from the infusion products of 12 ALL patients. We observed substantial heterogeneity in the antigen-specific activation states, among which a deficiency of T helper 2 function was associated with CD19-positive relapse compared with durable responders (remission, >54 months). Proteomic data revealed that the frequency of early memory T cells, rather than activation or coinhibitory signatures, could distinguish the relapse. These findings were corroborated by independent functional profiling of 49 patients, and an integrative model was developed to predict the response. Our data unveil the molecular mechanisms that may inform strategies to boost specific T cell function to maintain long-term remission.

Broadband and photovoltaic THz/IR response in the GaAs-based ratchet photodetector.

High-performance broadband infrared (IR)/terahertz (THz) detection is crucial in many optoelectronic applications. However, the spectral response range of semiconductor-based photodetectors is limited by the bandgaps. This paper proposes a ratchet structure based on the GaAs/AlxGa1-xAs heterojunction, where the quasi-stationary hot hole distribution and intravalence band absorption from light or heavy hole states to the split-off band overcome the bandgap limit, ensuring an ultrabroadband photoresponse from near-IR to THz region (4 to 300 THz). The peak responsivity of the proposed structure can reach 7.3 A/W, which is five orders of magnitude higher than that of the existing broadband photon-type detector. Because of the ratchet effect, the proposed photodetector has a bias-tunable photoresponse characteristic and can operate in the photovoltaic mode with a broad photocurrent spectrum (18 to 300 THz). This work not only demonstrates a broadband photon-type THz/IR photodetector but also provides a method to study the light-responsive ratchet.