Immunotherapy for genitourinary tumors

The present review provides an update about the major achievements and recent advances of immunotherapy in renal cell carcinoma, urothelial carcinoma, and prostate cancer. Although the treatment strategy for renal cell carcinoma and urothelial carcinoma includes traditional cancer immunotherapies, such as interleukin-2 and interferon-alfa, the clinical outcomes of these therapies are unsatisfactory. In recent years, the development of immune checkpoint inhibitors has drastically changed the treatment strategy for various cancers, including genitourinary cancer. The present review summarizes the approved cancer immunotherapies for renal cell carcinoma, urothelial carcinoma and prostate cancer. Furthermore, we review the response evaluation and biomarkers for immune checkpoint inhibitors with a distinctive mode of action that is different from cytotoxic agents. Finally, future perspectives for cancer immunotherapy are discussed.

T-Cell-Inflamed Gene-Expression Profile, Programmed Death Ligand 1 Expression, and Tumor Mutational Burden Predict Efficacy in Patients Treated With Pembrolizumab Across 20 Cancers: KEYNOTE-028

PURPOSE

Biomarkers that can predict response to anti-programmed cell death 1 (PD-1) therapy across multiple tumor types include a T-cell-inflamed gene-expression profile (GEP), programmed death ligand 1 (PD-L1) expression, and tumor mutational burden (TMB). Associations between these biomarkers and the clinical efficacy of pembrolizumab were evaluated in a clinical trial that encompassed 20 cohorts of patients with advanced solid tumors.

METHODS

KEYNOTE-028 ( ClinicalTrials.gov identifier: NCT02054806) is a nonrandomized, phase Ib trial that enrolled 475 patients with PD-L1-positive advanced solid tumors who were treated with pembrolizumab 10 mg/kg every 2 weeks for 2 years or until confirmed disease progression or unacceptable toxicity occurred. The primary end point was objective response rate (ORR; by RECIST v1.1, investigator review). Secondary end points included safety, progression-free survival (PFS), and overall survival (OS). Relationships between T-cell-inflamed GEP, PD-L1 expression, and TMB and antitumor activity were exploratory end points.

RESULTS

ORRs (with 95% CIs) ranged from 0% (0.0% to 14.2%) in pancreatic cancer to 33% (15.6% to 55.3%) in small-cell lung cancer. Across cohorts, median (95% CI) PFS ranged from 1.7 months (1.5 to 2.9 months) to 6.8 months (1.9 to 14.1 months) in pancreatic and thyroid cancers, respectively, and median OS from 3.9 months (2.8 to 5.5 months) to 21.1 months (9.1 to 22.4 months) in vulvar and carcinoid tumors, respectively. Higher response rates and longer PFS were demonstrated in tumors with higher T-cell-inflamed GEP, PD-L1 expression, and/or TMB. Correlations of TMB with GEP and PD-L1 were low. Response patterns indicate that patients with tumors that had high levels of both TMB and inflammatory markers (GEP or PD-L1) represent a population with the highest likelihood of response. Safety was similar and consistent with prior pembrolizumab reports.

CONCLUSION

A T-cell--inflamed GEP, PD-L1 expression, and TMB predicted response to pembrolizumab in multiple tumor types. These biomarkers (alone/in combination) may help identify patients who have a higher likelihood of response to anti-PD-1 therapies across a broad spectrum of cancers.

Oligometastatic prostate cancer: Reality or figment of imagination?

The term “oligometastatic prostate cancer” refers to a heterogeneous group of disease states currently defined solely on the basis of clinical features. Oligorecurrent disease, de novo oligometastases, and oligoprogressive disease likely have unique biologic underpinnings and natural histories. Evidence suggesting the existence of a subset of patients who harbor prostate cancer with limited metastatic potential currently includes disparate and overwhelmingly retrospective reports. Nevertheless, emerging prospective data have corroborated the “better‐than‐expected,” retrospectively observed outcomes, particularly in the setting of oligorecurrent prostate cancer. Improved functional imaging with prostate‐specific membrane antigen‐targeted strategies may enhance the identification of patients with oligometastatic prostate cancer in the short term. In the long term, refinement of the oligometastatic case definition likely will require biologic risk‐stratification schemes. To determine optimal treatment strategies and identify patients most likely to benefit from metastasis‐directed therapy, future efforts should focus on conducting high‐quality, prospective trials with much‐needed molecular correlative studies.

The term “oligometastatic prostate cancer” currently refers to a heterogeneous group of clinically defined disease states. To improve patient risk stratification and determine optimal treatment strategies, future efforts should focus on conducting prospective trials and determining a biologic categorization of patients with limited metastatic potential.

Clinical efficacy of immune checkpoint inhibitors in the treatment of unresectable advanced or recurrent gastric cancer: an evidence-based review of therapies

Standard treatment options for patients with advanced gastric cancer (GC) offer limited efficacy and are associated with some toxicity, which necessitates the development of more effective therapies for improving the treatment outcomes for this disease. Immunotherapy involving immune checkpoint inhibitors (ICIs) which inhibit the programmed death 1 (PD-1)/programmed death ligand 1 interaction has emerged as a new treatment option. Nivolumab, a human IgG4 monoclonal antibody inhibitor of PD-1, has demonstrated promising clinical activity and induced durable responses in patients with advanced GC. Nivolumab has recently been approved for treating patients with pretreated advanced GC in Japan. In the present review, we summarized current evidence of the clinical efficacy of ICIs in a variety of solid tumors and reported our experience in patients with GC who were treated with nivolumab and the interesting features that were observed in these cases. Certain ICI-specific clinical features such as pseudo- and hyper-progression of tumor and hyper-response to subsequent chemotherapy have been reported in several cancer types. Lastly, we discussed the present scenario regarding research on biomarkers for assessing the clinical benefits of ICI therapies.

Dosimetry Estimate and Initial Clinical Experience with 90Y-PSMA-617

Because of different physical properties, the β-emitters ¹⁷⁷Lu and ⁹⁰Y offer specific radiologic-biologic advantages in dedicated clinical situations. Our objective was to introduce ⁹⁰Y-labeled prostate-specific membrane antigen (PSMA)-617 to clinical application, providing additional avenues for personalized medicine. Here, we present our dosimetry estimate for ⁹⁰Y-PSMA-617, report first clinical experiences, and discuss the advantages and drawbacks of varying the β-emitter in PSMA-targeting radioligand therapy. Methods: To approximate radiation dosimetry, 4 patients with metastatic castration-resistant prostate cancer underwent serially performed imaging up to 1 wk after ¹⁷⁷Lu-PSMA-617 therapy. Time-activity curves were extrapolated to the half-life of ⁹⁰Y, and OLINDA was used to calculate the dosimetry estimate. In clinical practice, 11 patients with PSMA-positive lymph-nodal bulk disease were stratified to receive ⁹⁰Y-PSMA-617 radioligand therapy (mean, 3.2 GBq; range, 2.8-3.7 GBq); afterward, safety lab tests, prostate-specific antigen (PSA) response, and clinical findings were thoroughly followed. Results: The projected dosimetry for ⁹⁰Y-PSMA-617 estimated a mean kidney dose of 3.47 ± 1.40 Gy/GBq, red marrow dose of 0.11 ± 0.04 Gy/GBq, and salivary gland dose of 5.57 ± 1.34 Gy/GBq; randomly chosen metastases were approximated with 22.8 ± 16.10 Gy/GBq. The observed acute hematologic toxicity (5 cases of leukopenia and 2 of thrombocytopenia, all grade 1 or 2) and clinical side effects (2 cases of transient xerostomia and 1 of nausea, all grade 1 or 2), as well as PSA response (any PSA response, 7/11 patients; >50% PSA decline, 5/11 patients), were comparable to ¹⁷⁷Lu-PSMA-617 literature data. Conclusion: A factor 3-4 lower treatment activity for ⁹⁰Y-PSMA-617 translates into a comparable dosimetry estimate and clinical findings similar to those of ¹⁷⁷Lu-PSMA-617. However, safety was demonstrated only for patients with oligometastatic disease. Further studies are needed to evaluate its potential in patients with more disseminated bone involvement or visceral metastasis.

[Immunotherapy for the treatment of prostate cancer-a comeback?]

BACKGROUND

Prostate cancer (PCA) seems to be more of an immunologic desert than other tumor entities. It is striking that only rarely does prostate cancer show abundant immune cells and a proimmunogenic microenvironment.

OBJECTIVES

Is immunotherapy in PCA effective and which patients can benefit.

MATERIALS AND METHODS

A review of the literature and recent congress data are presented.

RESULTS

Preliminary results with sipuleucel-T for PCA cancer were very promising showing a significant overall survival benefit in randomised phase III studies and the US Federal Drug Administration (FDA) approval for this individualised vaccine. Contrary to other tumor entities this was not the immediate breakthrough to a new therapeutic era of immunotherapy but remained an isolated case and restricted to the USA. More recently, several trials evaluated immunotherapeutic agents but missed their preliminary endpoints. Interestingly, individual patients did benefit and showed long-term remission.

CONCLUSIONS

Genome sequencing and new biomarkers are also paving a novel pathway towards individualised immunotherapy for PCA. On-going research and clinical trials are exploring the question of which patients will benefit.