Research Signal – Source date 2021-02-01
Urothelial cancer begins in the lining of the urinary tract, including the bladder. For people whose cancer has spread locally or to distant parts of the body, treatment may involve chemotherapy and immunotherapy. But what happens when immunotherapy stops?
In two studies included in a 2021 review, 25% to 35.5% of patients received another treatment after stopping immunotherapy. The treatments that followed varied. These figures describe the patients in those studies, not the likelihood for every person with advanced urothelial cancer. The review also cannot tell us why a particular patient stopped treatment or did not receive another one.
A small evidence base gives a partial answer
The review searched for retrospective reports of treatment patterns in adults with locally advanced or metastatic urothelial cancer. It covered studies published from January 2013 through August 2018 and selected conference abstracts from 2017 and 2018. After screening 6,584 database records and 1,832 conference abstracts, the authors retained 45 publications representing 37 distinct studies.
All the retained publications described treatment patterns. The authors did not find eligible epidemiology studies in those searches, so they drew epidemiology information separately from online registries. Those registry sources and the treatment studies answer different questions: registries helped describe how common the cancer is, while treatment reports showed which therapies patients received in particular settings.
The treatment evidence came mostly from the United States, Japan, and the United Kingdom. The review included real-world records as well as analyses of people who had participated in clinical trials. Those settings are not interchangeable. Trial participants are a selected group, while routine-care reports reflect the patients treated in the settings covered by each study.
The review assessed 29 manuscripts and one poster for risk of bias; conference abstracts were not included in that assessment. Many studies were small, and more than half were based at a single center. This makes the two-study finding on treatment after immunotherapy useful as an observation, but too narrow to stand in for a universal rate.
The first chemotherapy choice varied too
The path before immunotherapy often began with platinum-based chemotherapy. The review described cisplatin-containing combinations as the standard starting treatment, called first-line therapy. Some patients were considered unsuitable for cisplatin and could receive carboplatin-based treatment instead. The review notes that factors such as kidney function, general health, hearing loss, nerve problems, and heart failure can matter when clinicians assess suitability.
In the studies reviewed, the share of patients receiving first-line cisplatin varied widely. Across ten U.S. studies, it ranged from 18.4% to 60.2%; in two Japanese studies, more than 80% received cisplatin. These differences show that treatment patterns depended on the particular study and care setting, as well as on patients’ circumstances.
Eligibility assessments did not always line up with the treatment patients actually received. In one multinational study, more than a quarter of patients assessed as cisplatin-eligible did not receive cisplatin, while nearly 35% of those assessed as ineligible did. A U.S. study likewise reported that 48.7% of eligible patients were not treated with cisplatin and 25.4% of ineligible patients received it. Eligibility and use measure different things: one describes an assessment, the other what treatment was given. The review does not explain each individual treatment decision.
Immunotherapy entered later lines of treatment
Immunotherapies that target PD-1 or PD-L1, proteins involved in the immune system’s interaction with cancer cells, became treatment options during the period covered by the review. The review describes their use after platinum-based chemotherapy and, for some patients who could not receive cisplatin, as an earlier option under the approvals and guidance current at the time.
Across the studies reporting immunotherapy use, it appeared more often in later treatment lines. Reported use ranged from 1.4% to 7.9% in first-line treatment, compared with 57.8% in second-line and 64.4% in third-line treatment. These figures come from different studies and patient groups; they should not be read as a single sequence that most patients followed.
The evidence included routine-care reports, retrospective analyses of clinical-trial participants, and one comparison between a trial population and a real-world cohort. The mix helps describe use across more than one setting, but it also makes direct comparisons difficult. The review was examining who received which treatments and when, rather than testing whether one sequence worked better than another.
After immunotherapy, another treatment was not assured
Several studies reported that many patients stopped immunotherapy. Across reports that gave discontinuation rates, 41.4% to 71% of patients discontinued; reported median time to discontinuation ranged from 2.7 to 5.8 months. These results show that treatment often ended within the periods captured by the studies, but they do not identify one reason for stopping. The review’s reports cannot establish whether a particular patient stopped because of disease changes, side effects, personal choice, or another circumstance.
Only two studies reported what happened next in a way that allowed the review to give a percentage. In those studies, 25% to 35.5% of patients received subsequent treatment after immunotherapy discontinuation. The reported next steps included chemotherapy, another immunotherapy, targeted therapies, and clinical-trial agents. The review also listed supportive care rather than another anticancer drug. The reports do not establish that one of these options improves survival compared with another.
A separate model estimated the number of U.S. patients moving through treatment and potentially reaching care after immunotherapy. It estimated that about 22,542 people were diagnosed with or progressed to locally advanced or metastatic disease each year, and that 11,600 received first-line treatment. The model estimated 1,795 patients would be eligible for post-immunotherapy treatment, including 1,352 whose disease progressed after chemotherapy and immunotherapy. These are modeled U.S. estimates, not observed counts from the two studies reporting subsequent treatment. Missing inputs prevented the authors from making an accurate comparable estimate for other countries.
Why the percentages cannot describe every treatment path
The review combined reports with different study designs, countries, treatment lines, and patient groups. Some studies had fewer than 30 patients; many used data more than five years old, and some did not account for factors that could affect comparisons between groups. A substantial share were single-center studies, which may not represent care across a country. The conference abstracts added information but were not part of the reported critical appraisal.
Treatment line was not specified in many studies, and reporting was not consistent enough to make all country or treatment comparisons straightforward. The epidemiology searches also did not yield eligible studies, leaving the authors to rely on registries for that part of the picture. Together, these limits mean the review can describe variation in reported practice, but cannot give a reliable universal forecast of who will receive another treatment after immunotherapy.
The review captures a treatment landscape shortly after immunotherapies began to be approved for this cancer. Its findings describe the literature and practice reports available through the review’s search period, not later treatment developments. The central gap was practical as well as scientific: published real-world evidence on treatment after immunotherapy was sparse, and the available studies showed that many patients did not have a subsequent treatment recorded.
What better options after immunotherapy could change
If newer treatments prove useful after immunotherapy and become available in routine care, people whose cancer progresses and who remain well enough for treatment could have another active option. The review raises that possibility because many patients in the two reported studies had no subsequent therapy recorded; it does not show that a newer option delivered that benefit.
The review’s two-study range describes how often another therapy was recorded in those reports. It cannot identify which option would help a particular patient or what outcome that patient could expect.
Key Sources
- Primary source: Epidemiology and treatment patterns for locally advanced or metastatic urothelial carcinoma: a systematic literature review and gap analysis.
DOI or Journal Page · Review or Meta-Analysis · 2021-02-01
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