Second-line therapies in metastatic urothelial carcinoma

The combination of immune checkpoint inhibitors and antibody-drug conjugates in the treatment of urogenital tumors: a review insights from phase 2 and 3 studies

With the high incidence of urogenital tumors worldwide, urinary system tumors are among the top 10 most common tumors in men, with prostate cancer ranking first and bladder cancer fourth. Patients with resistant urogenital tumors often have poor prognosis. In recent years, researchers have discovered numerous specific cancer antigens, which has led to the development of several new anti-cancer drugs. Using protein analysis techniques, researchers developed immune checkpoint inhibitors (ICIs) and antibody-conjugated drugs (ADCs) for the treatment of advanced urogenital tumors. However, tumor resistance often leads to the failure of monotherapy. Therefore, clinical trials of the combination of ICIs and ADCs have been carried out in numerous centers around the world. This article reviewed phase 2 and 3 clinical studies of ICIs, ADCs, and their combination in the treatment of urogenital tumors to highlight safe and effective methods for selecting individualized therapeutic strategies for patients. ICIs activate the immune system, whereas ADCs link monoclonal antibodies to toxins, which can achieve a synergistic effect when the two drugs are combined. This synergistic effect provides multiple advantages for the treatment of urogenital tumors.

Significant Improvement of Prognosis After the Advent of Immune Checkpoint Inhibitors in Patients with Advanced, Unresectable, or Metastatic Urothelial Carcinoma: A Propensity Score Matching and Inverse Probability of Treatment Weighting Analysis on Real-World Data

Purpose

The treatment landscape for advanced, unresectable, or metastatic urothelial carcinoma (aUC) has shifted substantially since the advent of immune checkpoint inhibitors (ICIs). We investigated the extent to which pembrolizumab therapy is superior to conventional chemotherapy as a second-line treatment.

Patients and Methods

A multicenter-derived database registered 454 patients diagnosed with aUC between 2008 and 2020. Of these, 94 patients (21%) who received second-line pembrolizumab and 75 (17%) who received second-line chemotherapy but never received third-line or later ICI therapy were included. We compared overall survival (OS) from the initial date of first-line chemotherapy between two groups by adjusting for prognostic factors through propensity score matching (PSM) and inverse probability of treatment weighting (IPTW). The IPTW-adjusted hazard ratio and 95% confidence interval were estimated using a multivariate Cox regression analysis. To identify patients who were more likely to benefit from second-line pembrolizumab than from chemotherapy, we performed a subgroup analysis for OS with an IPTW-adjusted model.

Results

The PSM-adjusted comparison showed a significant improvement in the prognosis with second-line pembrolizumab use (P = 0.01). The OS benefit with the advent of pembrolizumab was 8 months (18 months vs 26 months). Multivariable analyses using IPTW adjustment demonstrated that lymph node metastasis (P = 0.001), lung metastasis (P = 0.013), and bone metastasis (P = 0.003) were poor independent prognostic factors, and pembrolizumab use (P = 0.021) was a favorable independent prognostic factor. Subgroup analyses revealed that pembrolizumab was associated with survival benefits over chemotherapy in all subgroups, including young patients (age <70 years), those who received radical surgery, and those without visceral metastasis.

Conclusion

We demonstrated a significant improvement in prognosis after the advent of pembrolizumab for patients with aUC. ICIs should not be restricted based on patient characteristics.

Treatment Sequencing Patterns in Patients with Metastatic Urothelial Cancer Treated in the Community Practice Setting in the United States: SPEAR-Bladder (Study informing treatment Pathway dEcision in bladder cAnceR)

Purpose

Clinical trial evidence has affirmed the role for immuno-oncology (IO) treatment for locally advanced or metastatic urothelial carcinoma (la/mUC). This Study informing treatment Pathway dEcision in bladder cAnceR (SPEAR-Bladder) aimed to provide insight into the optimal sequencing of IO treatments among la/mUC patients treated in the US Oncology Network.

Patients and Methods

This was a retrospective analysis of adult patients with la/mUC who initiated first-line chemotherapy followed by either IO therapy (C-IO subgroup) or chemotherapy (C-C subgroup) between 01/01/2015 and 04/30/2017 and included a potential follow-up period through 06/30/2017. Data were sourced from iKnowMed electronic health records. Patient and treatment characteristics were assessed descriptively, with Kaplan-Meier methods used to evaluate time-to-event outcomes, including overall survival (OS).

Results

A total of 117 patients were included in this analysis (median age 69 years, 74.4% male, 88.0% Caucasian): 79 and 38 patients were in the C-IO and C-C subgroups, respectively. The median OS was 19.2 months among patients who received the C-IO sequence and 11.9 months among those who received the C-C treatment sequence.

Conclusion

These results suggest that patients who received the C-IO treatment sequence had notable improvement in OS compared with those who received the C-C sequence. In light of the rapidly evolving therapeutic landscape, further investigation will be required to determine how best to select the optimal therapeutic regimen and sequencing for patients with la/mUC.

Efficacy and Safety of Chemotherapy Regimens in Advanced or Metastatic Bladder and Urothelial Carcinomas: An Updated Network Meta-Analysis

Background: Gemcitabine plus cisplatin (GC) and methotrexate, vinblastine, adriamycin, and cisplatin (MVAC) have been the first-line treatments for advanced or metastatic urothelial carcinoma (AMUC). However, their effects are unsatisfactory, and more drugs and regimens still need to be explored.

Objective: We aimed to comprehensively compare all possible regimens with GC or MVAC in randomized controlled trials (RCTs) by network meta-analysis.

Methods: We searched the PubMed, Embase, and Cochrane databases for RCTs that evaluated regimens compared to GC or MVAC on AMUC patients. The major outcomes were progression-free survival (PFS), overall survival (OS), and objective response rate (ORR). A network meta-analysis was used to assess the effectiveness and safety of the included treatment regimens, and the regimens were then clustered by the average linkage method.

Results: A total of 19 trials that assessed 3,363 AMUC patients were included. For PFS, paclitaxel plus GC (PGC) was significantly superior to GC (log hazard ratio (HR): −0.16; 95% confidence interval (CI): −0.32, 0.00) with a moderate level of reliability. However, there was no significant difference between PGC and MVAC (log HR: −0.03; 95% CI: −0.27, 0.20). For OS, PGC was significantly superior to GC (log HR:−0.17; 95% CI: −0.33, −0.00) with a moderate reliability level but not significantly different from MVAC (log HR: −0.10; 95% CI: −0.35, 0.15). Analysis of ORR showed that PGC was superior to MVAC (log odds ratio (OR): 0.59; 95% CI: 0.02, 1.16) with a low reliability level and GC (log OR: 0.41; 95% CI: 0.12, 0.71) with a moderate reliability level. In the cluster results, PGC and sorafenib plus GC (GCS) exhibited relative advantages in efficiency, followed by MVAC and apatorsen plus GC (GCA); however, PGC, gemcitabine plus carboplatin (GP), and MVAC had more serious side effects.

Conclusions: In our analysis, PGC was superior to MVAC and GC in only the ORR results and superior to GC in the OS and PFS results but was not significantly different from MVAC. More individualized therapies with targeted drugs need to be studied.

Obatoclax and Paclitaxel Synergistically Induce Apoptosis and Overcome Paclitaxel Resistance in Urothelial Cancer Cells

Paclitaxel is a treatment option for advanced or metastatic bladder cancer after the failure of first-line cisplatin and gemcitabine, although resistance limits its clinical benefits. Mcl-1 is an anti-apoptotic protein that promotes resistance to paclitaxel in different tumors. Obatoclax, a BH3 mimetic of the Bcl-2 family of proteins, antagonizes Mcl-1 and hence may reverse paclitaxel resistance in Mcl-1-overexpressing tumors. In this study, paclitaxel-sensitive 5637 and -resistant HT1197 bladder cancer cells were treated with paclitaxel, obatoclax, or combinations of both. Apoptosis, cell cycle, and autophagy were measured by Western blot, flow cytometry, and fluorescence microscopy. Moreover, Mcl-1 expression was analyzed by immunohistochemistry in bladder carcinoma tissues. Our results confirmed that paclitaxel alone induced Mcl-1 downregulation and apoptosis in 5637, but not in HT1197 cells; however, combinations of obatoclax and paclitaxel sensitized HT1197 cells to the treatment. In obatoclax-treated 5637 and obatoclax + paclitaxel-treated HT1197 cells, the blockade of the autophagic flux correlated with apoptosis and was associated with caspase-dependent cleavage of beclin-1. Obatoclax alone delayed the cell cycle in 5637, but not in HT1197 cells, whereas combinations of both retarded the cell cycle and reduced mitotic slippage. In conclusion, obatoclax sensitizes HT1197 cells to paclitaxel-induced apoptosis through the blockade of the autophagic flux and effects on the cell cycle. Furthermore, Mcl-1 is overexpressed in many invasive bladder carcinomas, and it is related to tumor progression, so Mcl-1 expression may be of predictive value in bladder cancer.

Comparison of single agent versus combined chemotherapy in previously treated patients with advanced urothelial carcinoma: a meta-analysis

Background

Platinum-based chemotherapy is the standard treatment for advanced urothelial cancer (UC) and is generally used in the first-line setting. However, the optimal salvage treatment for previously treated UC patients is unclear. We conducted a systematic review of published clinical trials of single agent versus combined chemotherapy as salvage treatment in previously treated UC patients.

Methods

Trials published between 1994 and 2015 were identified by an electronic search of public databases (MEDLINE, EMBASE, Cochrane library). All relevant studies were independently identified by two authors for inclusion. Demographic data, treatment regimens, objective response rate (ORR), disease control rate (DCR), median progression-free and overall survival (PFS, OS), and grade 3/4 toxicities were extracted and analyzed using Comprehensive Meta Analysis software (Version 2.0).

Results

Fifty cohorts with 1,685 patients were included for analysis: 814 patients were treated with single agent chemotherapy and 871 with combined chemotherapy. Pooled OS was significantly higher at 1 year for combined chemotherapy than for single agent (relative risk [RR] 1.52; 95% CI: 1.01–2.37; P=0.03) but not for 2-year OS (RR 1.31; 95% CI: 0.92–1.85; P=0.064). Additionally, combined chemotherapy significantly improved ORR (RR 2.25; 95% CI: 1.60–3.18; P<0.001) and DCR (RR 1.12; 95% CI: 1.01–1.25, P=0.033) compared to single agent for advanced UC patients. As for grade 3 and 4 toxicities, more frequencies of leukopenia and thrombocytopenia were observed in the combined chemotherapy than in single agent group, while equivalent frequencies of anemia, nausea, vomiting, and diarrhea were found between the two groups.

Conclusion

In comparison with single agent alone, combined chemotherapy as salvage treatment for advanced UC patients significantly improved ORR, DCR, and 1-year OS, but not 2-year OS. Our findings support the need to compare combined chemotherapy with single agent alone in the salvage setting in large prospective trials due to its potential survival benefit in advanced UC patients.