LBA24 Cabozantinib (C) in combination with atezolizumab (A) in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC): Results of expanded cohort 6 of the COSMIC-021 study

Immunogenomic profiles associated with response to life-prolonging agents in prostate cancer

Prostate cancer is the most commonly diagnosed cancer but the management of advanced prostate cancer remains a therapeutic challenge, despite the survival benefits imparted by several therapeutic discoveries targeting different molecular pathways. The mechanisms of resistance to androgen deprivation and tumour progression to lethal metastatic variants are often regulated by androgen receptor (AR) bypass mechanisms and/or neuroendocrine differentiation. Moreover, recent data also suggested the involvement of adaptive and innate infiltrated immune cells in prostate tumour progression. Improvements in cancer genome analyses contributed to a better understanding of antitumour immunity and provided solutions for targeting highly cancer-specific neoantigens generated from somatic mutations in individual patients. In this review, we investigated the current knowledge on the interplay between cancer development and the complex mechanisms of immune regulation. Particularly, we focused on the role of tumour immune microenvironment, generally characterised by strong barriers for immunotherapy, and we discuss the rationale for the potential application of single agent and combination immune-targeting strategies that could lead to improved outcomes. Careful selection based on clinical and genomic factors may allow identification of patients who could benefit from this treatment approach in multiple settings (from localised to advanced prostate tumour) and in different histological subtypes (from adenocarcinoma to neuroendocrine prostate cancer).

Safety and efficacy of avelumab plus carboplatin in patients with metastatic castration-resistant prostate cancer in an open-label Phase Ib study

BACKGROUND

Single-agent PD-1/PD-L1 inhibitors have shown limited efficacy in unselected mCRPC. The evidence of a survival benefit with sipuleucel-T and ipilimumab, provides a rationale to study further increasing immunogenicity in mCRPC through combinations.

METHODS

Safety and efficacy avelumab plus carboplatin was investigated in a single-arm Phase Ib study in mCRPC, progressing to at least one taxane and one androgen-receptor inhibitor. The primary endpoint was safety. Secondary endpoints included PSA/radiographic responses, progression-free survival (PFS) and overall survival (OS). Germline/somatic mutation analysis was performed.

RESULTS

In total, 26 patients were included. Patients were heavily pretreated: 76.9% received ≥3 and 42.3% ≥4 prior lines. A DNA damage repair (DDR) alteration was found in three patients (11.5%). The safety profile was acceptable with 73% Grade 3-4 treatment-related adverse events. PSA response rate ≥50% was seen in 7.7% of patients. The objective response rate was 17.6%, including one complete response (5.9%). Two of these responders had a known DDR alteration (one BRCA2, one ATM). The median response duration was 6 months. Median radiographic PFS was 6.6 months (95% CI 4.28-9.01), and median OS 10.6 months (95% CI 6.68-NR).

CONCLUSIONS

Avelumab plus carboplatin has an acceptable safety profile and was associated with a prolonged OS given the heavily pretreated population.

Radiotherapy in Oligometastatic Prostate Cancer

Prostate cancer ranges from localized, low risk to metastatic, morbid disease. While radiotherapy is commonly incorporated in the treatment of early disease or for palliation of symptomatic lesions, its role in extending survival in metastatic disease is less well-established. Here, we review the available evidence surrounding localized radiotherapy in the presence of oligometastatic disease and metastasis-directed therapy in both hormone-sensitive and hormone-resistant prostate cancer. We further outline potential future incorporation of radiotherapy as an immune-sensitizing therapy and the importance of highly sensitive imaging modalities in considering radiotherapy in metastatic disease.

Immunotherapy in Advanced Prostate Cancer-Light at the End of the Tunnel?

Immunotherapeutic treatment approaches are now an integral part of the treatment of many solid tumors. However, attempts to integrate immunotherapy into the treatment of prostate cancer have been disappointing so far. This is due to a highly immunosuppressive, “cold” tumor microenvironment, which is characterized, for example, by the absence of cytotoxic T cells, an increased number of myeloid-derived suppressor cells or regulatory T cells, a decreased number of tumor antigens, or a defect in antigen presentation. The consequence is a reduced efficacy of many established immunotherapeutic treatments such as checkpoint inhibitors. However, a growing understanding of the underlying mechanisms of tumor–immune system interactions raises hopes that immunotherapeutic strategies can be optimized in the future. The aim of this review is to provide an overview of the current status and future directions of immunotherapy development in prostate cancer. Background information on immune response and tumor microenvironment will help to better understand current therapeutic strategies under preclinical and clinical development.

Immunotherapy in Advanced Prostate Cancer: Current Knowledge and Future Directions

The advent of immunotherapy has revolutionized cancer treatment. Unfortunately, this has not been the case for metastatic castration-resistant prostate cancer (mCRPC), likely due to the heterogeneous and immune-suppressive microenvironment present in prostate cancer. The identification of molecular biomarkers that could predict response to immunotherapy represents one of the current challenges in this clinical scenario. The management of advanced castration-resistant prostate cancer is rapidly evolving and immunotherapy treatments, mostly consisting of immune checkpoint inhibitors combinations, BiTE® (bispecific T-cell engager) immune therapies, and chimeric antigen receptors (CAR) are in development with promising results. This review analyses the current evidence of immunotherapy treatments for mCRPC, evaluating past failures and promising approaches and discussing the directions for future research.

Cabozantinib combination therapy for the treatment of solid tumors: a systematic review

Background:

Cabozantinib monotherapy is approved for the treatment of several types of solid tumors. Investigation into the use of cabozantinib combined with other therapies is increasing. To understand the evidence in this area, we performed a systematic review of cabozantinib combination therapy for the treatment of solid tumors in adults.

Methods:

This study was designed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses, and the protocol was registered with PROSPERO (CRD42020144680). On 9 October 2020, we searched for clinical trials and observational studies of cabozantinib as part of a combination therapy for solid tumors using Embase, MEDLINE, and Cochrane databases, and by screening relevant congress abstracts. Eligible studies reported clinical or safety outcomes, or biomarker data. Randomized and observational studies with a sample size of fewer than 25 and studies of cabozantinib monotherapy were excluded. For each study, quality was assessed using National Institute for Health and Care Excellence methodology, and the study characteristics were described qualitatively. This study was funded by Ipsen.

Results:

Of 2421 citations identified, 32 articles were included (6 with results from randomized studies, 24 with results from non-randomized phase I or II studies, and 2 with results from both). The most commonly studied tumor types were metastatic urothelial carcinoma/genitourinary tumors and castration-resistant prostate cancer (CRPC). Findings from randomized studies suggested that cabozantinib combined with other therapies may lead to better progression-free survival than some current standards of care in renal cell carcinoma, CRPC, and non-small-cell lung cancer. The most common adverse events were hypertension, diarrhea, and fatigue.

Conclusion:

This review demonstrates the promising efficacy outcomes of cabozantinib combined with other therapies, and a safety profile similar to cabozantinib alone. However, the findings are limited by the fact that most of the identified studies were reported as congress abstracts only. More evidence from randomized trials is needed to explore cabozantinib as a combination therapy further.