Low doses in immunotherapy: Are they effective?

Implementing and assessing Bayesian response-adaptive randomisation for backfilling in dose-finding trials

Traditional approaches in dose-finding trials, such as the continual reassessment method, focus on identifying the maximum tolerated dose. In contemporary early-phase dose-finding trials, especially in oncology with targeted agents or immunotherapy, a more relevant aim is to identify the lowest dose level that maximises efficacy whilst remaining tolerable. Backfilling, defined as the practice of assigning patients to dose levels lower than the current highest tolerated dose, has been proposed to gather additional pharmacokinetic, pharmacodynamic and biomarker data to recommend the most appropriate dose to carry forward for subsequent studies. The first formal framework [5] for backfilling proposed randomising backfill patients with equal probability among those doses below the dose level where the study is currently at. Here, we propose to use Bayesian response-adaptive randomisation to backfill patients. This patient-oriented approach to backfilling aims to allocate more patients to dose levels in the backfill set with higher expected efficacy based on emerging data. The backfill set constitutes of the doses below the dose the dose-finding algorithm is at. At study completion, collective patient data inform the dose-response curve, suggesting an optimal dose level balancing toxicity and efficacy. Our simulation study across diverse clinical trial settings demonstrates that a backfilling strategy using Bayesian response-adaptive randomisation can result in a patient-oriented patient assignment procedure which simultaneously enhances the likelihood of correctly identifying the most appropriate dose level. This contribution offers a methodological framework and practical implementation for patient-oriented backfilling, encompassing design and analysis considerations in early-phase trials.

Reduced frequency dosing of osimertinib in EGFR-mutant non-small cell lung carcinoma: real world data

Introduction

Osimertinib is more efficacious and as safe as first-generation epidermal growth factor receptor (EGFR)-directed tyrosine kinase inhibitors. However, osimertinib is not affordable for most patients in developing nations. Moreover, the minimum biologically effective dose of osimertinib may be less than the approved dose.

Materials and methods

This was a retrospective observational multicentric study aimed to describe the efficacy (objective response rate (ORR), disease control rate (DCR), progression free survival (PFS), overall survival (OS)) and toxicity of osimertinib 80 mg orally administered less frequently than daily (ranging from every other day to once-a-week) in patients with EGFR-mutated non-small cell lung cancer.

Results

Between January 2021 and August 2023, we enrolled 22 patients. Six received osimertinib 80 mg once-a-week, nine received 80 mg once-in-3-days and seven received 80 mg on alternate days. Responses included 0 complete responses, 7 (31.8%) partial responses, 9 (40.9%) stable disease and 5 (22.7%) progressive disease. ORR was 31.8%, and DCR was 72.7%. Median PFS was 9.2 months (95% confidence interval (CI) 2.9-15.7), and median OS was 17.8 months (95% CI, 3.2-32.6). In patients who received reduced frequency osimertinib in the second line and beyond, the ORR was 29.4%, DCR was 70.5%, median PFS was 5.9 months (95% CI, 1.1-10.6) and median OS was 17.6 months (95% CI, 2.9-32.2). Grade 3 and higher toxicities were noted in 8 (36.3%) patients.

Conclusion

Less frequent dosing of osimertinib may be a valid treatment option, especially in the second line and beyond setting in patients who cannot afford full dose daily osimertinib. This may provide an additional treatment option with a similar toxicity profile as that of standard dose osimertinib.

Patient and public involvement and engagement in the development of innovative patient-centric early phase dose-finding trial designs

BACKGROUND

In light of the FDA's Project Optimus initiative, there is fresh interest in leveraging Patient-reported Outcome (PRO) data to enhance the assessment of tolerability for investigational therapies within early phase dose-finding oncology trials. Typically, dose escalation in most trial designs is solely reliant on clinician assessed adverse events. Research has shown a disparity between patients and clinicians when assessing whether an investigational therapy is tolerable, leading to the recommendation of potentially intolerable doses for further investigation in subsequent trials. It is also increasingly recognized that patient and public involvement and engagement (PPIE) plays a pivotal role in enriching trial design and conduct. However, to our knowledge, no PPIE has explored the optimal integration of PROs in the development of advanced statistical trial designs within early phase dose-finding oncology trials.

METHODS

A virtual PPIE session was held with nine participants on 18th October 2023 to discuss the incorporation of PROs within a dose-finding trial design. This cross disciplinary session was developed and led by a team of statisticians, clinical specialists, qualitative experts, and trial methodologists. Following the session, in-depth perspectives were provided by two patient advocates who actively engaged in the PPIE session. We discuss the importance of PPIE in shaping advanced dose-finding trial designs, share insights from patients on integrating PROs to inform treatment tolerability, and present a template for meaningful patient involvement in trial design development.

RESULTS

Participants generally supported the introduction of PROs within dose-finding trials but showed some apprehensiveness as to how PROs may reduce the size of the recommended dose (and potentially efficacious effect). Some participants shared that they may be reluctant to record the real severity of their symptoms via PROs if it would mean that they would have to discontinue treatment. They discussed that PROs could be used to assess tolerability rather than toxicity of a dose.

CONCLUSIONS

Amplifying patient voice in the development of patient-centric dose-finding trial designs is now essential. This paper offers an exemplary illustration of how trialists and methodologists can effectively incorporate patient voice in the future development of advanced dose-finding trial designs.

Low-dose immunotherapy as a potentiator to increase the response with neo-adjuvant chemotherapy in oral cancers

Neo-adjuvant chemotherapy (NACT) is utilized in locally advanced oral cancers to reduce the tumor burden and downstage the tumor to be amenable for definitive surgical management. Its long-term results compared to upfront surgical resection was not encouraging. Immunotherapy has now been used not only in recurrence and metastatic setting but also in the locally advanced tumor management regimens. The purpose of this concept paper is to bring forward the rationale to use a fixed low-dose immunotherapy agent as a potentiator to the standard NACT regimen and recommend their future investigation in oral cancer management.

Low-Dose Immunotherapy: Is It Just an Illusion?

The development and use of immunotherapy in the last decade have led to a drastic improvement in results in the onco-haematological field. This has implied, on the one hand, the need for clinicians to manage a new type of adverse event and, on the other hand, a significant increase in costs. However, emerging scientific evidence suggests that, as with other drugs in the recent past, the registry dosage can be drastically reduced for immunotherapies without penalizing their effectiveness. This would also lead to an important reduction in costs, expanding the audience of cancer patients who could access immunotherapy-based treatments. In this “Commentary”, we analyze the available evidence of pharmacokinetics and pharmacodynamics and the most recent literature in favor of low-dose immunotherapy.

Controlled amplification in oncology dose-finding trials

In oncology clinical trials the guiding principle of model-based dose-finding designs for cytotoxic agents is to progress as fast as possible towards, and identify, the dose level most likely to be the MTD. Recent developments with non-cytotoxic agents have broadened the scope of early phase trials to include multiple objectives. The ultimate goal of dose-finding designs in our modern era is to collect the relevant information in the study for final RP2D determination. While some information is collected on dose levels below and in the vicinity of the MTD during the escalation (using conventional tools such as the Continual Reassessment Method for example), designs that include expansion cohorts or backfill patients effectively amplify the information collected on the lower dose levels. This is achieved by allocating patients to dose levels slightly differently during the study in order to take into account the possibility that "less (dose) might be more". The objective of this paper is to study the concept of amplification. Under the heading of controlled amplification we can include dose expansion cohorts and backfill patients among others. We make some general observations by defining these concepts more precisely and study a specific design that exploits the concept of controlled amplification.

Low-Dose Immunotherapy in Head and Neck Cancer: A Randomized Study

PURPOSE

The regimens approved for the treatment of advanced head and neck squamous cell carcinoma are accessible to only 1%-3% of patients in low- and middle-income countries because of their cost. In our previous study, metronomic chemotherapy improved survival in this setting. Retrospective data suggest that a low dose of nivolumab may be efficacious. Hence, we aimed to assess whether the addition of low-dose nivolumab to triple metronomic chemotherapy (TMC) improved overall survival (OS).

METHODS

This was a randomized phase III superiority study. Adult patients with recurrent or newly diagnosed advanced head and neck squamous cell carcinoma being treated with palliative intent with an Eastern Cooperative Oncology Group performance status of 0-1 were eligible. Patients were randomly assigned 1:1 to TMC consisting of oral methotrexate 9 mg/m² once a week, celecoxib 200 mg twice daily, and erlotinib 150 mg once daily, or TMC with intravenous nivolumab (TMC-I) 20 mg flat dose once every 3 weeks. The primary end point was 1-year OS.

RESULTS

One hundred fifty-one patients were randomly assigned, 75 in TMC and 76 in the TMC-I arm. The addition of low-dose nivolumab led to an improvement in the 1-year OS from 16.3% (95% CI, 8.0 to 27.4) to 43.4% (95% CI, 30.8 to 55.3; hazard ratio, 0.545; 95% CI, 0.362 to 0.820; P = .0036). The median OS in TMC and TMC-I arms was 6.7 months (95% CI, 5.8 to 8.1) and 10.1 months (95% CI, 7.4 to 12.6), respectively (P = .0052). The rate of grade 3 and above adverse events was 50% and 46.1% in TMC and TMC-I arms, respectively (P = .744).

CONCLUSION

To our knowledge, this is the first-ever randomized study to demonstrate that the addition of low-dose nivolumab to metronomic chemotherapy improved OS and is an alternative standard of care for those who cannot access full-dose checkpoint inhibitors.

Retrospective analysis: checkpoint inhibitor accessibility for thoracic and head and neck cancers and factors influencing it in a tertiary centre in India

Background

Access to cancer care is an issue in low and low middle-income countries. The problem is worse with respect to access to new therapies like checkpoint inhibitors. Hence, we decided to audit our practice in the head and neck and thoracic medical oncology unit from 2015 to 2019 to study the accessibility of checkpoint inhibitors and factors influencing it.

Methods

All patients who were registered in the head and neck and thoracic medical oncology unit between 2015 and 2019 were included in the study. Patients who received immunotherapy were identified from the prospective database of immunotherapy maintained by the department. We made a list of patients who were eligible for immunotherapy per year and identified how many of them received recommended immunotherapy. The indication for eligibility of immunotherapy was based on published pivotal data and it was applicable from the date of publication of the study online. Descriptive statistics were performed. For nominal and ordinal variable percentage with 95% confidence intervals (95% CI) was provided. Factors impacting the accessibility of immunotherapy were identified.

Findings

A total of 15,674 patients were identified who required immunotherapy; out of them only 444 (2.83%, 95% CI: 2.58-3.1) received it. Among head and neck cancer patients, 4.5% (156 out of 3,435) received immunotherapy versus 2.35% (288 out of 12,239) among thoracic cancer patients (p < 0.001). Among the general category (low socioeconomic), 0.29% (28 out of 9,405 ) versus 6.6% (416 out of 6,269) among the private category (high socioeconomic) received immunotherapy (p < 0.001). While 3.7% (361 out of 9,737) among males versus 1.39% (83 out of 5,937) females received immunotherapy (p < 0.001). There was also a temporal trend seen in the accessibility of immunotherapy (p < 0.001).

Conclusion

The accessibility of immunotherapy is below 3% in India. Patients with head and neck cancers, those registered as private category and male patients had higher access to this therapy. There was also a temporal trend observed suggesting increased accessibility over the years.

Controlled backfill in oncology dose-finding trials

The use of backfill in early phase dose-finding trials is a relatively recent practice. It consists of assigning patients to dose levels below the level where the study is at. The main reason for backfilling is to collect additional pharmacokinetic, pharmacodynamic and response data, in order to assess whether a plateau may exist on the dose-efficacy curve. This is a possibility in oncology with molecularly targeted agents or immunotherapy. Recommending for further study a dose level lower than the maximum tolerated dose could be supported in such situations. How to best allocate backfill patients to dose levels is not yet established. In this paper we propose to randomise backfill patients below the dose level where the study is at. A refinement of this would be to stop backfilling to lower dose levels when these show insufficient efficacy compared to higher levels, starting at dose level 1 and repeating this process sequentially. At study completion, data from all patients (both backfill patients and dose-finding patients) is used to estimate the dose-response curve. The fit from a change point model is compared to the fit of a monotonic model to identify a potential plateau. Using simulations, we show that this approach can identify the plateau on the dose-response curve when such a plateau exists, allowing the recommendation of a dose level lower than the maximum tolerated dose for future studies. This contribution provides a methodological framework for backfilling, from the perspective of both design and analysis in early phase oncology trials.

The clinical utility and safety of short-course immune checkpoint inhibitors in multiple tumours-A real-world multicentric study from India

The real-world data on short course of immune checkpoint inhibitor (ICI) use are sparse and merit exploration. A multicentric observational study on the safety and efficacy of ICI in oncology patients between August 2014 and October 2020 involves 1011 patients across 13 centers in India. The median age was 59 (min 16-max 98) years with male preponderance (77.9%). The predominant cohort received short-course ICI therapy; the median number of cycles was 5 (95% confidence interval [CI] 1-27), and the median duration of therapy was 3 (95% CI 0.5-13) months. ICIs were used commonly in the second and third line setting in our study (66.4%, n = 671). Objective response rate (complete or partial response) was documented in 254 (25.1%) of the patients, 202 (20.0%) had stable disease, and 374 (37.0%) had progressive disease. The clinical benefit rate was present in 456 (45.1%). Among the patients whom ICI was stopped (n = 906), the most common reason for cessation of ICI was disease progression (616, 68.0%) followed by logistic reasons like financial constraints (234, 25.82%). With a median follow-up of 14.1 (95% CI 12.9-15.3) months, there were 616 events of progression and 443 events of death, and the median progression free survival and overall survival were 6.4 (95% CI 5.5-7.3) and 13.6 (95% CI 11.6-15.7) months, respectively, in the overall cohort. Among the immune-related adverse events, autoimmune pneumonitis (29, 3.8%) and thyroiditis (24, 2.4%) were common. Real-world multicentric Indian data predominantly with short-course ICI therapy have comparable efficacy/safety to international literature with standard ICI therapy.

A novel role for an old target: CD45 for breast cancer immunotherapy

Breast cancer subtypes have not shown significant response to current immunomodulatory therapies. Although most subtypes are treatable, triple negative breast cancer (TNBC), an aggressive highly metastatic cancer, comprising 10-20% of breast cancers, remains an unmet medical need. New strategies are needed in order to overcome flaws in the responsiveness to current TNBC therapies. Our aims were: first, to determine the efficacy of a novel immunomodulatory peptide, C24D, on TNBC and second, to elucidate the molecular mechanism by which C24D induces immune-modulating tumor killing. Using mass spectrometry analysis, we identified CD45 as the C24D binding receptor. In vitro and in vivo TNBC models were used to assess the efficacy of C24D in reversing TNBC-induced immunosuppression and in triggering immune-modulated tumor cell killing. The CD45 signal transduction pathway was evaluated by western blot and FACS analyses. We revealed that addition of PBMCs from healthy female donors to TNBC cells results in a cascade of suppressive CD45 intracellular signals. On binding to CD45's extra-cellular domain on TNBC-suppressed leukocytes, the C24D peptide re-activates the Src family of tyrosine kinases, resulting in specific tumor immune response. In vitro, immune reactivation by C24D results in an increase of CD69+ T and CD69+ NK cells, triggering specific killing of TNBC cells. In vivo, C24D induced CD8+ and activated CD56+ tumor infiltrated cells, resulting in tumor apoptosis. Our results should renew interest in molecules targeting CD45, such as the C24D peptide, as a novel strategy for TNBC immunotherapy.