Bispecific PSMA antibodies and CAR-T in metastatic castration-resistant prostate cancer

PSMA-based Therapies and Novel Therapies in Advanced Prostate Cancer: The Now and the Future

OPINION STATEMENT

The treatment landscape for metastatic castration-resistant prostate cancer (mCRPC) is rapidly evolving with the advent of PSMA-targeted radioligand therapies (RLTs) and bispecific T-cell engagers (BiTEs). These novel approaches provide new hope for patients who have progressed on standard therapies. However, their full clinical potential will be realized only by addressing key challenges, including tumor heterogeneity, resistance mechanisms, immune-related toxicities, and the immunosuppressive tumor microenvironment. Additionally, the optimal sequencing of these therapies at different stages of disease remains an open question. While most of these interventions are currently introduced in late-stage, heavily pretreated patients, ongoing clinical trials are exploring their role in earlier disease settings, where they may be more effective in altering the natural history of disease. PSMA-based RLTs, such as 177Lu-PSMA- 617, have demonstrated promising efficacy, particularly in patients with high PSMA expression. However, the presence of PSMA-negative or heterogeneous tumors necessitates the development of additional biomarkers and combination strategies. The ongoing PSMAddition trial may establish RLTs as an earlier-line treatment in hormone-sensitive metastatic prostate cancer, potentially shifting the standard of care. Moreover, mitigating toxicities through radioprotective agents may aid in expanding their clinical utility. BiTE therapies offer a different but complementary mechanism of action, leveraging T-cell engagement to drive tumor cell destruction. While cytokine release syndrome (CRS) and immunogenicity remain significant hurdles, modifications such as low-affinity CD3 binding and optimized dosing regimens are showing promise. The potential synergy of BiTEs with immune checkpoint inhibitors and tumor microenvironment-modulating agents should be further explored to enhance therapeutic efficacy. Given these advancements, the future of mCRPC treatment likely lies in a personalized, multimodal approach that integrates PSMA-based RLTs, BiTEs, and complementary therapies at earlier disease stages. Strategic biomarker-driven patient selection and combination regimens will be essential in optimizing outcomes while minimizing resistance and toxicity.

Advances in Targeted Therapy for Metastatic Prostate Cancer

OPINION STATEMENT

Over the past few years, treatment for advanced prostate cancer has begun shifting away from a one-size-fits-all approach toward biomarker-based therapies for select groups of patients. This review highlights the role of poly-ADP-ribose-polymerase (PARP) inhibitors in metastatic prostate cancer, emerging strategies to target the androgen receptor (AR), and innovative therapies aimed at cell surface proteins, including radioligand therapies, bispecific T cell engagers, and antibody-drug conjugates. For patients with homologous recombination repair (HRR)-mutated metastatic castration-resistant prostate cancer (CRPC), we favor combining a PARP inhibitor (PARPi) with an AR pathway inhibitor (ARPI), provided they can tolerate a more aggressive treatment strategy. In our opinion, patients with BRCA1 or BRCA2 mutations who are unable to handle combination therapy benefit from PARPi monotherapy. We are enthusiastic about the potential of ongoing clinical trials for new AR-directed therapies, such as AR ligand-directed degraders and CYP11A1 inhibitors, in metastatic CRPC. These treatments are expected to be most beneficial for patients whose cancer continues to rely on AR pathway signaling, suggesting they might also be effective in earlier stages of the disease. Progress in drug development and understanding of protein structures has led to new therapies that target cell surface proteins predominantly found in prostate cancer. We use 177Lu-PSMA-617 for patients with PSMA avid metastatic CRPC who have progressed on an ARPI and a taxane chemotherapy. Additionally, we see promising potential in bispecific T-cell engagers (e.g., STEAP1-CD3 and PSMA-CD3) and novel radioligand therapies, including those utilizing actinium, to target these proteins. These advances show great promise in further enhancing survival for patients with metastatic prostate cancer.

Novel Methods to Assess Tumor Burden and Minimal Residual Disease in Genitourinary Cancers

BACKGROUND AND OBJECTIVE

Advances in molecular diagnostics have ushered in a new era for patients with prostate, renal, and urothelial cancers, with novel radiographic and molecular modalities for the assessment of disease burden and minimal residual disease (MRD). Conventional imaging has a limited threshold for disease detection and is often unable to discern clinically occult disease with varying risks of false-negative or false-positive findings depending on the disease state and type of imaging.

METHODS

We provide an overview of emerging radiographic and molecular tools in development within the genitourinary (GU) disease space. A literature review of contemporary basic, translational, and clinical research studies was performed, covering the timeframe of 1980-2024 through the MEDLINE (via PubMed) and Scopus databases. We highlight select examples of emerging technologies and biomarker-informed clinical trials, which aim to quantify disease at lower thresholds and have the potential for integrating MRD in clinical practice for GU patients.

KEY FINDINGS AND LIMITATIONS

The development of novel radiotracers, such as prostate-specific membrane antigen or carbonic anhydrase IX, is being evaluated in both clinical practice and trial setting, aiming to change the management of these tumors. Molecular tools including circulating tumor cells and byproducts such as plasma and urine cell-free circulating tumor DNA provide the opportunity for MRD detection. MRD capture on single-cell or cellular byproducts can serve as a conduit for genomic and transcriptomic analyses, providing insight into the molecular underpinnings and clonal evolution of disease.

CONCLUSIONS AND CLINICAL IMPLICATIONS

While the full potential for MRD applications has yet to be realized, we are witnessing the emergence of novel techniques aimed at MRD detection and the rapid development of elegantly designed studies implementing iterative detection of MRD as means to provide biological rationale and tailor therapeutic options in GU tumors.

Bone metastases of prostate cancer: Molecular mechanisms, targeted diagnosis and targeted therapy (Review)

Prostate cancer (PCa) is second only to lung cancer in terms of death among men worldwide. Advanced PCa frequently results in bone metastases, which occur in ~90% of patients and frequently result in severe skeleton‑related events. Currently, the treatment for this disease is limited to alleviating its clinical symptoms and cannot provide a complete cure. Therefore, the development of novel treatment strategies is particularly important. In recent years, numerous novel strategies for the diagnosis and treatment of PCa have emerged, resulting in good clinical efficacy. For example, strategies targeting prostate specific membrane antigen, poly ADP‑ribose polymerase and programmed cell death protein 1 have been applied to PCa‑induced bone metastasis, and have shown initial efficacy and great potential. Therefore, understanding the molecular mechanisms underlying the formation of bone metastases in patients with PCa is of importance for the effective management of this disease. The purpose of the present review is to comprehensively outline the roles of protein‑coding genes and non‑coding RNAs in the development of bone metastases of PCa to elucidate their significance in the management of PCa. The aim is to offer clinicians and researchers a comprehensive understanding of this topic.

Prostate Cancer: De-regulated Circular RNAs With Efficacy in Preclinical In Vivo Models

Therapy resistance, including castration-resistance and metastasis, remains a major hurdle in the treatment of prostate cancer. In order to identify novel therapeutic targets and treatment modalities for prostate cancer, we conducted a comprehensive literature search on PubMed to identify de-regulated circular RNAs that influence treatment efficacy in preclinical prostate cancer-related in vivo models. Our analysis identified 49 circular RNAs associated with various processes, including treatment resistance, transmembrane and secreted proteins, transcription factors, signaling cascades, human antigen R, nuclear receptor binding, ubiquitination, metabolism, epigenetics and other target categories. The identified targets and circular RNAs can be further scrutinized through target validation approaches. Down-regulated circular RNAs are candidates for reconstitution therapy, while up-regulated RNAs can be inhibited using small interfering RNA (siRNA), antisense oligonucleotides (ASO) or clustered regularly interspaced short palindromic repeats/CRISPR associated (CRISPR-CAS)-related approaches.

Natural Killer Cell Infiltration in Prostate Cancers Predict Improved Patient Outcomes

BACKGROUND

Natural killer (NK) cells are non-antigen specific innate immune cells that can be redirected to targets of interest using multiple strategies, although none are currently FDA-approved. We sought to evaluate NK cell infiltration into tumors to develop an improved understanding of which histologies may be most amenable to NK cell-based therapies currently in the developmental pipeline.

METHODS

DNA (targeted/whole-exome) and RNA (whole-transcriptome) sequencing was performed from tumors from 45 cancer types (N = 90,916 for all cancers and N = 3365 for prostate cancer) submitted to Caris Life Sciences. NK cell fractions and immune deconvolution were inferred from RNA-seq data using quanTIseq. Real-world overall survival (OS) and treatment status was determined and Kaplan-Meier estimates were calculated. Statistical significance was determined using X2 and Mann-Whitney U tests, with corrections for multiple comparisons where appropriate.

RESULTS

In both a pan-tumor and prostate cancer (PCa) -specific setting, we demonstrated that NK cells represent a substantial proportion of the total cellular infiltrate (median range 2-9% for all tumors). Higher NK cell infiltration was associated with improved OS in 28 of 45 cancer types, including (PCa). NK cell infiltration was negatively correlated with common driver mutations and androgen receptor variants (AR-V7) in primary prostate biopsies, while positively correlated with negative immune regulators. Higher levels of NK cell infiltration were associated with patterns consistent with a compensatory anti-inflammatory response.

CONCLUSIONS

Using the largest available dataset to date, we demonstrated that NK cells infiltrate a broad range of tumors, including both primary and metastatic PCa. NK cell infiltration is associated with improved PCa patient outcomes. This study demonstrates that NK cells are capable of trafficking to both primary and metastatic PCa and are a viable option for immunotherapy approaches moving forward. Future development of strategies to enhance tumor-infiltrating NK cell-mediated cytolytic activity and activation while limiting inhibitory pathways will be key.

Evidence-Based Recommendations on the Use of Immunotherapies and Monoclonal Antibodies in the Treatment of Male Reproductive Cancers

The incidence of male reproductive cancers, including prostate, testicular, and penile cancers, has risen in recent years, raising important health concerns. Prostate cancer is the second leading cause of cancer-related mortality in men, while penile cancer, though rare, typically affects men over 60. Testicular cancer, with a lifetime risk of about 0.4% in men, is most common among adolescents and young adults, decreasing sharply after the age of 40. Traditional treatments include chemotherapy, radiation, surgery, and combinations thereof, but advancements in immunotherapy and monoclonal antibodies are showing promising results, particularly for genitourinary cancers. These therapies, targeting immune checkpoints and tumor-specific antigens, are gaining traction as effective alternatives for resistant cases. This review provides evidence-based recommendations on current and emerging immunotherapy and monoclonal antibody treatments for male reproductive cancers, highlighting future directions to optimize patient outcomes.

T-Cell redirecting bispecific antibodies: a review of a novel class of immuno-oncology for advanced prostate cancer

Novel T-cell immunotherapies such as bispecific T-cell engagers (BiTEs) are emerging as promising therapeutic strategies for prostate cancer. BiTEs are engineered bispecific antibodies containing two distinct binding domains that allow for concurrent binding to tumor-associated antigens (TAAs) as well as immune effector cells, thus promoting an immune response against cancer cells. Prostate cancer is rich in tumor associated antigens such as, but not limited to, PSMA, PSCA, hK2, and STEAP1 and there is strong biologic rationale for employment of T-cell redirecting BiTEs within the prostate cancer disease space. Early generation BiTE constructs employed in clinical study have demonstrated meaningful antitumor activity, but challenges related to drug delivery, immunogenicity, and treatment-associated adverse effects limited their success. The ongoing development of novel BiTE constructs continues to address these barriers and to yield promising results in terms of efficacy and safety. This review will highlight some of most recent developments of BiTE therapies for patients with advanced prostate cancer and the evolving data surrounding BiTE constructs undergoing clinical evaluation.

Leveraging Vγ9Vδ2 T cells against prostate cancer through a VHH-based PSMA-Vδ2 bispecific T cell engager

Vγ9Vδ2 T cells constitute a homogeneous effector T cell population that lyses tumors of different origin, including the prostate. We generated a bispecific T cell engager (bsTCE) to direct Vγ9Vδ2 T cells to PSMA+ prostate cancer (PCa) cells. The PSMA-Vδ2 bsTCE triggered healthy donor and PCa patient-derived Vγ9Vδ2 T cells to lyse PSMA+ PCa cell lines and patient-derived tumor cells while sparing normal prostate cells and enhanced Vγ9Vδ2 T cell antigen cross-presentation to CD8+ T cells. Vγ9Vδ2 T cell expressed NKG2D and DNAM-1 contributed to Vγ9Vδ2 T cell activation and tumor lysis at low PSMA-Vδ2 bsTCE concentrations. In vivo models confirmed the antitumor efficacy of the bsTCE and demonstrated a half-life of 6-7 days. Tissue-cross reactivity analysis was in line with known tissue distribution of PSMA and Vγ9Vδ2 T cells. Together these data show the PSMA-Vδ2 bsTCE to represent a promising anti-tumor strategy and supports its ongoing evaluation in a phase 1/2a clinical trial in therapy refractory metastatic castration-resistant PCa.

Immunome profiling in prostate cancer: a guide for clinicians

Tumor immune microenvironment (TIME) plays a key role to understand how tumors respond to prostate cancer (PC) therapies and potential mechanisms of resistance. Previous research has suggested that specific genomic aberrations, such as microsatellite instability (MSI) or CDK12 bi-allelic loss can allow PC patients more likely to respond to immune checkpoint inhibitors (ICI) or other immune therapies. However, responses to these treatments remain highly variable even in selected patients. Thus, it is essential to obtain more information about tumor immune cells that infiltrate these tumors, and on their plasticity and interactions, in order to better understand the underlying biology to allow development of new therapeutic strategies. This review analyzes: 1) How interactions among immune cell populations and other cells infiltrating the tumor stroma can modulate the progression of PC, 2) How the standard therapies to treat PC (such as androgen deprivation therapy, new androgen-directed hormone therapy or chemotherapy) may influence the dynamic changes of the immunome and 3) What are the limitations in characterizing the immune landscape of the host´s response to tumors.

Next-Generation Therapeutic Antibodies for Cancer Treatment: Advancements, Applications, and Challenges

The field of cancer treatment has evolved significantly over the last decade with the emergence of next-generation therapeutic antibodies. Conventional treatments like chemotherapy pose significant challenges, including adverse side effects. Monoclonal antibodies have paved the way for more targeted and effective interventions. The evolution from chimeric to humanized and fully human antibodies has led to a reduction in immunogenicity and enhanced tolerance in vivo. The advent of next-generation antibodies, including bispecific antibodies, nanobodies, antibody-drug conjugates, glyco-engineered antibodies, and antibody fragments, represents a leap forward in cancer therapy. These innovations offer increased potency, adaptability, and reduced drug resistance. Challenges such as target validation, immunogenicity, and high production costs exist. However, technological advancements in antibody engineering techniques provide optimism for addressing these issues. The future promises a paradigm shift, where ongoing research will propel these powerful antibodies to the forefront, revolutionizing the fight against cancer and creating new preventive and curative treatments. This review provides an overview of three next-generation antibody-based molecules, namely bispecific antibodies, antibody-drug conjugates, and nanobodies that have shown promising results in cancer treatment. It discusses the evolution of antibodies from conventional forms to next-generation molecules, along with their applications in cancer treatment, production methods, and associated challenges. The review aims to offer researchers insights into the evolving landscape of next-generation antibody-based cancer therapeutics and their potential to revolutionize treatment strategies.

CAR‑T cell therapy: A breakthrough in traditional cancer treatment strategies (Review)

Chimeric antigen receptor (CAR)‑T cell therapy is an innovative approach to immune cell therapy that works by modifying the T cells of a patient to express the CAR protein on their surface, and thus induce their recognition and destruction of cancer cells. CAR‑T cell therapy has shown some success in treating hematological tumors, but it still faces a number of challenges in the treatment of solid tumors, such as antigen selection, tolerability and safety. In response to these issues, studies continue to improve the design of CAR‑T cells in pursuit of improved therapeutic efficacy and safety. In the future, CAR‑T cell therapy is expected to become an important cancer treatment, and may provide new ideas and strategies for individualized immunotherapy. The present review provides a comprehensive overview of the principles, clinical applications, therapeutic efficacy and challenges of CAR‑T cell therapy.