The CD47 protein, often overexpressed in various cancers, including lung cancer, plays a critical role in immune evasion by sending a “don’t eat me” signal to macrophages, thus inhibiting their phagocytic activity [7] [16] . This overexpression is not just a passive trait of tumor cells; in non-small cell lung cancer (NSCLC), mutations in the epidermal growth factor receptor (EGFR) are known to upregulate CD47, further impeding macrophage function and promote tumor growth [17] . This mechanism enables cancer cells to escape immune surveillance, contributing to disease progression and resistance to therapy.

The CD47-SIRPα interaction does more than just prevent macrophage phagocytosis; it also plays a significant role in regulating the broader immune response. For example, CD47’s inhibition of immune activity can lead to CD4+ T cell exhaustion, weakening the body’s ability to fight the tumor [18] . This finding underscores the potential of targeting CD47 to rejuvenate T cell activity and improve outcomes in immunotherapy. By disrupting this pathway, there is potential to reinvigorate exhausted T cells and enhance anti-tumor immunity [19] , which could significantly impact the effectiveness of ongoing cancer treatments.

Given its role in immune evasion, the CD47-SIRPα axis has become a promising target for cancer therapy. Inhibitors of this pathway, such as anti-CD47 antibodies, are currently under investigation in clinical trials, with preliminary results revealing enhanced macrophage phagocytosis and improved anti-tumor responses. On the other hand, challenges remain, including potential adverse effects and the need to ensure specificity and safety in therapy [16] [19] . Moreover, Research is also exploring SIRPα as a narrower target, primarily in cancers where CD47 blockade alone may not be sufficient.

Beyond the horizon of just blocking phagocytosis, the CD47-SIRPα interaction also influences macrophage polarization and the tumor microenvironment. To illustrate, in NSCLC, blocking SIRPα has been shown to reduce IL-6 levels and decrease the presence of immunosuppressive M2 macrophages, thereby enhancing anti-tumor immunity [23] . In a similar manner, in high-risk neuroblastoma, targeting SIRPα could shift macrophage polarization towards a more pro-inflammatory state, accelerating tumor clearance. Additionally, emerging research highlights the role of microRNAs, such as miR-378a, which modulates SIRPA, influencing macrophage phagocytosis and differentiation. Atherosclerosis models with reduced miR-378a expression show decreased phagocytic activity [24] , in regulating this pathway, further adding complexity to its role in cancer progression and offering new avenues for therapeutic intervention. In summary, SIRPA signaling plays a crucial role in shaping macrophage responses, which has implications for cancer therapy and inflammatory diseases. Despite its complexity, its regulation, including the involvement of microRNAs calls for a refined approach to therapeutic targeting.

The CD47-SIRPα pathway plays a crucial role in the tumor microenvironment by inhibiting macrophage phagocytosis of cancer cells [25] [26] . This pathway mediates the “don’t eat me” signal within the tumor microenvironment, contributing to the suppression of anti-tumor immunity. Tumors often overexpress CD47 to evade immune destruction, and this overexpression can also influence other immune cells within the microenvironment, such as myeloid-derived suppressor cells (MDSCs), which further enhance immunosuppressive functions [27] . Blocking the CD47-SIRPα interaction has been shown to improve macrophage-mediated phagocytosis and reduce tumor burden, particularly in models of diffuse large B cell lymphoma [28] . This blockade not only enhances the direct phagocytic activity of macrophages but also influences the broader immune response by reducing the immunosuppressive effects of MDSCs and potentially altering the tumor microenvironment to favor anti-tumor immunity. Conversely, further research is needed in order to optimize these therapeutic strategies to ensure safety and efficacy in a clinical setting.

Targeting the CD47-SIRPα axis presents a promising avenue in cancer therapy, with ongoing clinical trials evaluating approaches such as SIRPα fusion proteins to improve efficacy and reduce adverse effects. Despite that, while these therapies hold promise, further research is necessary to optimize their use and ensure they are both safe and effective in a clinical environment.

Monoclonal antibodies against CD47 have gained significant attention for their ability to promote macrophage-mediated phagocytosis of tumor cells. Agents such as IMC-002 and MIL95 have shown promise in early-phase trials, demonstrating manageable safety profiles and preliminary efficacy in advanced solid tumors without dose-limiting toxicities [29] [30] . Furthermore, Fc-engineered variants of these antibodies have been engineered to increase binding to target FcγRs, thereby enhancing systemic anti-tumor immunity and reducing off-target effects [31] . Innovations such as pH-dependent anti-CD47 antibodies, highlighted by BC31M4, selectively target tumors in acidic microenvironments, reducing side effects on healthy tissue [32] .

The development of fusion proteins and bispecific antibodies has introduced novel approaches to CD47-targeted therapy. These therapies aim to enhance immune responses while minimizing adverse effects. For instance, a bispecific antibody targeting both CD38 and CD47 has demonstrated potent inhibition of tumor growth in hematologic malignancies, enhancing antibody-dependent cellular cytotoxicity (ADCC) with minimal off-tumor effects [33] . Similarly, dual targeting of CD47 and PD-L1 by agents like Papiliximab has shown effectiveness in tumor growth inhibition without causing hemolysis [34] .

Despite the promising developments in CD47-targeted therapies, challenges persist, particularly regarding safety and efficacy. CD47 is widely expressed in healthy cells, which raises concerns about adverse effects such as anemia and other hematological disorders. Clinical trials have highlighted the need for combination strategies to enhance the anti-tumor activity of these therapies. As demonstrated, combining anti-CD47 therapies with other treatments, such as anti-VEGF, has shown enhanced anti-tumor effects in preclinical models [35] . However, further refinement is required to maximize therapeutic potential and minimize side effects.

TKIs function by inhibiting the tyrosine phosphorylation process is crucial for various cellular activities such as cell proliferation and survival [36] [37] . These drugs target specific mutations in kinases, like BCR-ABL and EGFR, which are commonly implicated in cancers such as chronic myeloid leukemia (CML) and non-small cell lung cancer (NSCLC). However, the efficacy of TKIs is often compromised by resistance mechanisms, including mutations in kinase domains and alternative signaling pathways [14] .

TKI therapy has significantly improved survival rates and quality of life in patients with certain cancers. For instance, elderly patients with CML have an overall survival rate of 71.9% five years post-treatment with optimal doses of TKIs [38] . However, the therapy is not without limitations; adverse effects such as significant toxicities in medullary thyroid cancer (MTC) and the risk of therapy failure in approximately 20% - 30% of CML patients underscore the need for better management strategies [39] .

Resistance to TKI monotherapy still represents a significant barrier to cancer treatment. Mechanisms such as the activation of TRAF6/MAPK/AP-1 pathways in clear cell renal cell carcinoma (ccRCC) and MET gene amplification in NSCLC contribute to acquired resistance [40] [41] . However, to overcome this, combination therapies with other agents, such as HDAC inhibitors or chemotherapy, have shown promise in reversing resistance and improving treatment outcomes [42] .

CD47-SIRPα blockade enhances macrophage-mediated tumor cell clearance by inhibiting the “don’t eat me” signal provided by CD47, particularly in RCCs where high CD47 expression is related to poor outcomes [43] . When combined with TKIs, this approach not only promotes macrophage activation but also enhances trogocytosis, further boosting anti-tumor effects [43] .

Preclinical studies have demonstrated the synergistic potential of combining CD47 blockade with TKIs. For example, in head and neck squamous cell carcinoma, CD47 blockade enhanced macrophage adhesion and improved antibody-dependent cellular phagocytosis (ADCP) when combined with cetuximab, a TKI [44] . Furthermore, studies combining radiotherapy with CD47 inhibition have shown macrophage-mediated abscopal effects, improving tumor control beyond the site of radiation [45] .

Despite the potential of combining TKIs with CD47 blockade, several challenges remain. The suppressive tumor microenvironment and the risk of anemia due to CD47’s expression on erythrocytes complicate treatment [19] . Future research should focus on optimizing dosing and patient selection, and exploring the use of hybrid nanoplatforms to deliver CD47-targeting agents alongside chemotherapy to enhance efficacy and minimize adverse effects [46] .

The combination of CD47-SIRPα blockade with tyrosine kinase inhibitors provides notable promise for cancer treatment, offering a potential new therapeutic frontier. While challenges remain, particularly in terms of safety and resistance mechanisms, ongoing research and innovation are forecasted to develop new strategies that enhance the efficacy of these therapies and improve patient outcomes. This collaborative approach showcases the future of cancer treatment, where targeted therapy and immune modulation work in concert to defeat the complexities of the disease.

High CD47 expression correlates with a poor prognosis in diffuse large B-cell lymphoma (DLBCL), characterized by an immunosuppressive microenvironment and increased macrophage infiltration. This suggests that CD47-targeted therapies may be less effective in patients with elevated CD47 levels, requiring a deeper understanding of the tumor microenvironment and its influence on therapy efficacy [47] .

The effectiveness of CD47-targeted therapies is further complicated by genetic factors, with CD47 overexpression often parallel to mutations in oncogenes such as TBL1XR1 and NOTCH1. These genetic alterations can lead to inconsistent therapeutic responses, underscoring the need for personalized approaches in CD47 blockade therapy [47] .

Preclinical studies with CD47-targeted CAR T cells have shown limited efficacy due to fratricide and poor expansion [48] , highlighting the challenges in translating these therapies from bench to bedside. Clinical trials have also encountered setbacks, with some CD47-targeting agents proving ineffective as monotherapies [49] .

There are a number of factors that play a significant role in regulating the expression of CD47, which is important for evading the immune system of cancer cells. MiR-101-5p, in particular, has been identified as a key regulator of CD47 expression. A high level of miR-101-5p enhances macrophage phagocytosis, which improves treatment response in cancers such as diffuse large B-cell lymphoma. There is evidence that miR-101-5p can predict the efficacy of CD47-targeted therapies, indicating a need to investigate microRNA-based strategies for cancer treatment [49] . Despite this, tumor heterogeneity complicates this approach. Different tumor types and tumors within the same type can express CD47 differently, affecting therapeutic response consistency. CD47 blockade may not always work uniformly on tumors with high CD47 expression due to factors such as tumor microenvironment and genetics, which led to disappointing outcomes in recent clinical trials, highlighting the need for more refined regulatory mechanisms [50] .

Hematotoxicity, particularly anemia, remains a significant barrier to the development of CD47 blockade therapies. This adverse effect has not only narrowed the therapeutic window but has also led to the discontinuation of several trials. Ongoing research aims to mitigate this toxicity, but effective strategies are still under exploration [51] . In future clinical trials exploring CD47 blockade, hematotoxicity will be a crucial factor in ensuring its feasibility and safety. Considering lower doses or extended dosing intervals will minimize anemia while still maintaining therapeutic efficacy in future clinical studies. In addition to erythropoiesis-stimulating agents (ESAs) and iron supplementation, other approaches to managing hematologic side effects include CD47-targeted treatments that can prevent anemia. Furthermore, early detection of hematotoxicity via biomarkers is critical for personalized treatment, allowing adjustments according to individual responses and preventing more severe adverse effects. The key to overcoming hematotoxicity and improving the safety profile of CD47 blockade therapies will be to optimize dosing, combine supportive therapies, and monitor hematologic status early.

The immunosuppressive tumor microenvironment, marked by M2 macrophage polarization in the presence of CD47 overexpression, further complicates the effectiveness of CD47-targeted therapies [47] . This necessitates the development of combinatorial approaches to enhance therapeutic efficacy [16] .

Although current preclinical models of CD47-SIRPα blockade show promise, they still fall short of accurately replicating the complexity of the human tumor microenvironment (TME), which includes immune cell interactions and tumor heterogeneity, all of which greatly affect the effectiveness of therapy. Research should focus on improving preclinical models by incorporating patient-derived xenografts (PDXs) and organ-on-a-chip technologies that more closely mimic human immune responses and tumor characteristics. Additionally, for clinical translation to be successful, it is crucial to identify biomarkers, such as CD47 expression levels, macrophage activation markers, and immune cell infiltration markers. This will facilitate more accurate patient stratification and enhance therapeutic efficacy. It may also be possible to monitor these biomarkers in real time using liquid biopsies, allowing for personalized treatment adjustments. Aside from hematotoxicity, the challenge of managing anemia remains. Efforts should be made to mitigate these effects by optimizing doses, using erythropoiesis-stimulating agents (ESAs), and supplementing iron in future trials. Finally, adaptive trial designs will be crucial to identifying optimal dosing regimens and combination therapies, allowing for adjustments based on patient response and ultimately improving clinical success.

A combination of CD47-SIRPα blockade and tyrosine kinase inhibitors (TKIs) holds significant promise in cancer therapy, especially for cancers where CD47 overexpression facilitates immune evasion, such as non-small cell lung cancer (NSCLC) and renal cell carcinoma (RCC) [7] [16] . Using this approach, macrophage-mediated phagocytosis can be enhanced and immune cells can be stimulated, which provides an efficient complement to TKIs that target oncogenic signaling pathways. CD47 blockade with TKIs has been shown to improve tumor clearance and immune response in preclinical studies [43] . The results of studies on different cancer types are, however, contradictory. In contrast to RCC, other solid tumors, like head and neck squamous cell carcinoma, show mixed responses, with variable macrophage adhesion and antibody-dependent cellular phagocytosis (ADCP) [44] . Aside from hematotoxicity, particularly anemia, the combination of CD47 blockage with TKIs remains a critical concern due to CD47 expression on erythrocytes, complicating clinical implementation. Aside from hematotoxicity, particularly anemia, the combination of CD47 blockage with TKIs remains a critical concern due to CD47 expression on erythrocytes, complicating clinical implementation [19] . Moreover, immune resistance mechanisms, such as alternative immune checkpoints, can limit the therapeutic efficacy, emphasizing the need to identify biomarkers to improve patient selection and dose optimization. A novel combination strategy, such as pairing CD47 blockade with chemotherapy or radiotherapy, should be explored in the future to overcome these challenges and improve treatment outcomes [46] . In spite of the hurdles, combining CD47-SIRPα blockade and TKIs remains a promising avenue for enhancing anti-tumor immunity and overcoming cancer resistance.

Combining CD47 blockade with other therapeutic modalities has shown promise in enhancing anti-tumor responses. For instance, photodynamic therapy has been found to synergize with CD47 blockade by enhancing phagocytic activity and promoting dendritic cell maturation, thereby improving overall therapeutic outcomes [52] .

In a comparable manner, the novel inhibitor HOSU-53 has demonstrated effective monotherapy in multiple myeloma while also synergizing with anti-CD47 therapies [53] .

The development of advanced drug delivery systems, such as engineering exosomes to display RGD and CD47p110-130, has remarkably improved the targeting of pancreatic cancer cells. These smart exosomes not only enhance targeting efficiency but also reduce clearance by mononuclear phagocytes, thereby increasing the therapeutic window [54] .

The optimization of Fc domains in anti-CD47 antibodies has been shown to encourage macrophage infiltration and subsequent T cell activation, which are vital for effective tumor control. This approach highlights the importance of Fc-FcR interactions in the anti-tumor activities of CD47-targeted therapies [31] .

Tyrosine kinase inhibitors (TKIs) have become a fundamental element in targeted cancer therapy, particularly in malignancies driven by specific oncogenic kinases. The combination of TKIs with CD47 blockade represents a promising strategy to overcome resistance and improve treatment effectiveness.

The synergistic effect of TKIs and CD47 blockade has been demonstrated in various preclinical models, paving the way for clinical trials exploring this combination in different cancer types. Early results suggest that this dual approach could lead to more durable responses and improved patient outcomes compared to monotherapies [53] .

The integration of CD47-SIRPα blockade with TKIs holds significant potential, but critical challenges must be addressed to advance this strategy. First, systemic CD47 blockade often causes anemia and thrombocytopenia due to on-target/off-tumor effects; tumor-specific CD47 delivery systems (e.g. bispecific antibodies, nanocarriers) or optimized dose-escalation protocols should be prioritized to mitigate toxicity. Second, current preclinical models, such as immunocompromised mice, poorly replicate human immune-tumor interactions; humanized mouse models or 3D patient-derived organoids with intact immune components are urgently needed to improve clinical translatability. Third, the mechanisms underlying resistance to TKI-CD47 combinations remain unclear; single-cell RNA sequencing of the tumor microenvironment post-therapy could identify drivers of immune evasion and guide rational drug sequencing.

To refine patient selection, biomarker validation is essential: candidate markers like CD47/SIRPα expression levels, PD-L1 status, and tumor mutational burden should be prospectively tested in clinical cohorts. Additionally, adaptive trial designs incorporating biomarker-guided arms (e.g. CD47-high vs. CD47-low subgroups) will help define responsive populations. Systematic testing of TKI-CD47 dosing schedules (concurrent vs. staggered) is essential to optimize the balance between efficacy and safety. Longitudinal immune monitoring should also be incorporated to evaluate adaptive memory responses and potential autoimmune risks. Additionally, combining TKI-CD47 therapies with radiotherapy or chemotherapy could enhance antigen release and immune priming, while SIRPα occupancy assays may provide valuable pharmacodynamic markers to inform dosing strategies. By addressing these challenges and implementing actionable strategies—ranging from improved preclinical models to biomarker-driven clinical trials—this combination approach has the potential to address current limitations and contribute meaningfully to the advancement of precision oncology.

The field of CD47-targeted therapies is on the brink of a paradigm shift, with emerging therapies poised to not only enhance efficacy but also minimize adverse effects. These advancements are expected to redefine cancer treatment strategies by leveraging novel antibodies and intricate regulatory mechanisms.

The development of “Gentulizumab”, a humanized anti-CD47 monoclonal antibody, marks a significant breakthrough in oncology. This antibody exhibits potent anti-tumor activity while maintaining a favorable safety profile, primarily by inhibiting CD47-SIRPα interactions, thereby amplifying macrophage-mediated phagocytosis [55] . Another promising candidate, “AO-176”, a next-generation anti-CD47 antibody, distinguishes itself with negligible red blood cell (RBC) binding. AO-176 induces tumor cytotoxicity through a unique mechanism, diverging from traditional CD47-targeting agents [56] .

Cutting-edge research has identified microRNAs, such as “miR-101-5p”, as key regulators of CD47 expression in diffuse large B-cell lymphoma. This discovery opens the door to new therapeutic strategies where modulating such regulatory elements could enhance the efficacy of CD47-targeted treatments [49] .

While these innovations are promising, the journey towards fully optimized CD47-targeted therapies is not without challenges. Recent clinical trial setbacks underscore the need for continued exploration and refinement of these approaches [50] .

One of the key mechanisms involves “EGFR activation”, which upregulates CD47 expression in tumors, thereby suppressing macrophage phagocytosis and promoting immune evasion [59] . Combining CD47 blockade with TKIs has been shown to enhance the efficacy of existing therapies, primarily by increasing macrophage activity and improving overall immune function [19] .

The therapeutic potential of CD47-targeted therapies is increasingly being validated through clinical trials, which indicate promising improvements in patient outcomes [19] [58] . However, challenges remain, notably the issue of anemia caused by CD47 expression on erythrocytes, which must be meticulously managed [19] .

Despite the focus on cancer, the role of CD47 in immune modulation suggests broader applications, even in non-neoplastic diseases. This highlights the necessity for ongoing research into CD47’s mechanisms and the exploration of potential combinations with other treatments [60] .

The future of cancer immunotherapy lies in the complex harmony between targeted therapies and immune modulation, with a particular emphasis on CD47-SIRPα blockade and TKIs. This combined approach aims to not only enhance the immune response against tumors but also to overcome innate resistance mechanisms that often undermine treatment effectiveness.

The interaction between CD47 and SIRPα, which signals macrophages to avoid consuming tumor cells, is a crucial target in cancer therapy. Blocking this interaction has been shown to enhance antibody-dependent cellular phagocytosis (ADCP), especially in head and neck squamous cell carcinoma (HNSCC), where it synergizes effectively with “Cetuximab”, a targeted therapy for HNSCC [44] . Furthermore, ATP release, driven by type I interferons, plays a pivotal role in T cell activation and the reprogramming of tumor metabolism, essential for the efficacy of CD47-SIRPα blockade [61] .

Combining CD47-SIRPα blockade with TKIs has shown promise in preclinical models by enhancing macrophage function and restoring immune competency. This dual approach could potentially overcome the immune suppression prevalent in tumor microenvironments, offering a multifaceted attack on cancer [62] .

In summary, while CD47-SIRPα blockade holds substantial promise for enhancing cancer immunotherapy, the risks, such as anemia and the critical importance of patient selection, must be carefully navigated for successful clinical implementation [19] .