POPCORN is a signal-seeking study to provide information about the magnitude of pharmacodynamic effect, activity (clinical/pathological response) and safety of combination anti-RANKL (denosumab) and anti-PD1 (nivolumab) compared with anti-PD1 (nivolumab) alone in the preoperative treatment of resectable NSCLC.
A total of 30 patients with NSCLC will be enrolled in this study. Eligible patients will be adults with stage IA (>2cm)-IIIA non-small cell lung cancer who have been deemed suitable for up-front curative treatment via surgery by a cardiothoracic surgeon as part of a lung cancer multidisciplinary team. Potential study participants will be identified through the lung cancer multidisciplinary teams at participating trial sites.
Inclusion and exclusion criteria
Inclusion criteria were as follows: adult patients with histological or cytological diagnosis of NSCLC with 8th edition UICC/AJCC 2017 stage I, II or IIIA NSCLC (tumour ≥ 2 cm diameter) as assessed by staging investigations including by FDG-PET scan (with strong encouragement to pathologically confirm the status of suspected N2 nodes); measurable primary tumour on CT scan (3mm slice thickness) per RECIST criteria; sufficient baseline histological specimen from primary tumour (and locoregional lymph node metastasis if clinically suspected) available for translational research; no prior therapy for NSCLC; ECOG performance status 0-1; and adequate organ function. To be eligible for the study, patients must be considered to have potentially resectable disease on the basis of the preoperative investigations. They must be physiologically suitable for surgery, and the expected post-surgical FEV1 must be at least 1 L.
Exclusion criteria were as follows: patients with small cell or mixed small cell histology subtypes; prior malignancy within 5 years (other than non-melanoma skin cancer or adequately treated stage I in situ cervical cancer); recent receipt of another investigational drug or anti-cancer treatment; any prior treatment with therapies targeting T-cell immune checkpoint pathways or denosumab; active, known or suspected autoimmune disease (with certain exceptions such as vitiligo or type 1 diabetes mellitus); use of corticosteroids (at a dosage equivalent of 10 mg prednisolone per day or higher); contraindication to corticosteroids; and concomitant medical or psychiatric disorders which would compromise the patient’s safety or participation (including dental disorders such as pre-existing osteonecrosis of the jaw, recent live vaccine, or serious hypersensitivity to trial drugs).
POPCORN is an open-label, multi-centre phase 1B/2 study with a pharmacodynamic endpoint. It will be conducted in 4 centres in Australia. Randomization by minimisation is performed at the Statistics Unit of Queensland Institute of Medical Research with stratification by histology (squamous vs. non-squamous) and tumour stage.
The schedule of study assessments is shown in Figure 1. CONSORT diagram for the trial is shown in Figure 2 (31). SPIRIT checklist is shown in Additional File 1.
A subject will have completed the study interventions approximately 8 weeks after the first dose of study drug (encompassing neoadjuvant treatment and surgery). All AEs will be followed up for a maximum of 90 days after the final dose of study drug; therefore the subject is considered as entering the survival follow-up phase after 90 days post-surgery. Subsequently, patients will be followed according to the institution’s standard practice. The close-out date of the trial will be three months after surgery for the final randomized participant, but with a further three years’ follow-up after the end of accrual to record long-term survival outcomes. Any adjuvant treatment, date and site of progression, date of death and cause of death will be recorded.
Neoadjuvant systemic therapy will occur on two separate occasions, two weeks apart. In arm A, on each occasion participants will receive nivolumab (3 mg/kg i.v.) whereas in arm B, participants will receive nivolumab (3 mg/kg i.v.) and denosumab (120 mg s.c.) (Figure 3). All patients in arm B will also receive calcium and vitamin D supplementation unless hypercalcemia is present, and hypocalcemia must be corrected prior to initiating therapy.
Surgery should be carried out on day 29 (± 3 days) of the study (2 weeks after the second dose of nivolumab +/- denosumab). The surgical operation to remove the primary tumour should be lobectomy, pneumonectomy or anatomical segmentectomy and other surgery as required. Thoracoscopic surgical techniques are permitted. Wedge resection or non-anatomical surgical dissection is not permitted. Surgery should also include appropriate mediastinal lymph node sampling or dissection and macroscopic margins of ≥ 2 cm and microscopic margins of ≥ 1 cm should be aimed for.
All patients should be offered appropriate adjuvant therapy as per institutional practice according to the recommendations of treating clinicians, preferably based on a multidisciplinary team review. It is strongly recommended this consist of 4 cycles of a platinum doublet chemotherapy (common regimen consisting of cisplatin 50 mg/m2 days 1 and 8 and vinorelbine 25 mg/m2 days 1, 8, 15 +/- 22 every 4 weeks for 4 cycles). Adjuvant chemotherapy should be considered in patients with pre-study nodal involvement (N1 or N2), a primary tumour >4cm and at the discretion of the treating investigator. Post-operative radiotherapy should also be considered in patients with pathologically confirmed N2 nodal involvement or positive surgical resection margins (R1 disease).
Intervention safety monitoring and assessment
Adverse events (AE), defined as any untoward medical occurrence(s) in a trial participant regardless of causality with trial interventions, will be systematically monitored and recorded. These will be classified and graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events version 4.03 (NCI CTCAE v4.03). Serious AEs (SAE) will be reported to the appropriate ethics committees and competent authorities as well as the study safety committee. A suspected unexpected serious adverse reaction (SUSAR) which is an unexpected SAE related to the intervention will additionally be reported to the drug manufacturer. If the AE is deemed by the investigator to have been caused, or probably caused, by the investigational treatment (nivolumab and/or denosumab), this will be labelled a TRAE (treatment-related adverse event).
Study participants will be reviewed clinically for the presence of AEs by the site investigator prior to each cycle of neoadjuvant therapy, prior to surgery, and four weeks following surgery. Blood tests, including complete blood count, liver and renal function tests, electrolytes, thyroid function tests and serum cortisol will be reviewed at these visits. Immune-related adverse events are managed following algorithms as compiled by expert groups or as available in the product information (32). Rechallenge after a suspected TRAE is permitted provided symptoms resolve to an appropriate level to meet criteria to resume treatment and do not meet any of the permanent discontinuation criteria (such as grade 4, and select grade 3 toxicities). Dose reductions and dose escalations are not permitted. An independent data safety monitoring committee will monitor the conduct and safety of the trial during recruitment.
A pregnancy test is mandated for women of childbearing age within 72 hours of commencing treatment and must be negative. Patients on study with reproductive potential, or female partners with reproductive potential, must use an effective contraceptive method during the trial and for 3 months after the completion of chemotherapy.
All patients are recommended to have a dental examination prior to commencing denosumab, maintain good oral hygiene while on denosumab, and avoid invasive dental procedures during treatment with denosumab and for at least a month after the final dose of denosumab. If osteonecrosis of the jaw is suspected, treatment with denosumab is halted and the patient assessed by a dentist or oral surgeon.
The primary endpoint is to define pharmacodynamic correlates of neoadjuvant therapy for each arm (combination anti-RANKL and anti-PD1 compared with anti-PD1 alone) in NSCLC. This is a signal-seeking study for this endpoint. Pharmacodynamic correlates will include the following parameters assessed in tumour and, where relevant, blood:
- T-cell receptor (TCR) clonality, comparing baseline and on-/post-treatment samples
- RNA/transcription profile changes for immune cells and other cells of interest, to define treatment response
- Analysis of genomic alterations, including estimation of expressed mutation-associated neoantigen load, and association with treatment response
- Expression of markers of interest via multiplex immunohistochemistry (formalin-fixed, paraffin-embedded tumour samples) and/or flow cytometry (fresh, dissociated tumour tissue or peripheral blood mononuclear cells)
Schedule for biobanking of clinical materials is shown in Figure 4. Formalin-fixed, paraffin-embedded tumour tissue will be stored at baseline (pre-treatment) and surgical timepoints, with participants strongly encouraged to consent for tumour biopsy for translational research purposes in the event of recurrent or metastatic disease. Collection of non-fixed tumour, including nodal metastases, will be performed where feasible with the assistance of trial site surgeon and pathologist. The fresh materials will be transported to the central laboratory (where possible within two hours of operation) and dissociated and processed on the same day. Blood will be collected at baseline, before each neoadjuvant systemic treatment, at the time of surgery, at the post-surgery visit, and in the event of tumour recurrence. This will be processed in the central trial laboratory, for storage of serum and peripheral blood mononuclear cells.
Secondary and exploratory endpoints are defined as follows, and will be compared between arms:
- The proportion of patients with evidence of pathological response as determined by blinded central pathology review, including major pathological response (MPR) (defined as <10% viable tumour cells in resected specimen)
- Response by CT scanning, with timepoint response assessed per RECIST v1.1 comparing baseline and pre-operative scans
- Rates of NCI CTCAE v4.03 grade 3-4 toxicity will be assessed by comparing the proportion of patients in each arm who are noted to have an AE of grade 3-4, regardless of causality.
- Proportion of patients in each arm who receive planned surgery without delay due to TRAE will be compared. If the surgery cannot proceed due to an unforeseen factor that was deemed by the investigator to probably not be caused by the investigational treatment, this will be recorded but will not be deemed delay due to TRAE. A delay is defined as an event where the surgery is rescheduled for >24 hours later than originally planned due to clinical considerations.
- Feasibility of approach as reflected in R0 resection rate, which will be assessed based upon the operative and pathological report arising from the surgical resection. An R0 resection indicates that there is a microscopically- and macroscopically-negative margin.
- As an exploratory endpoint, progression-free survival (PFS) (defined as time between randomization and first evidence of disease progression or death from any cause) and overall survival (OS) (defined as time between randomization and death from any cause) will be recorded for trial participants in each group, for 3 years of follow-up or the latest available data, whichever is longer.
As a signal-seeking study, the emphasis of this project is on gaining an understanding of the mechanism of action, activity and safety of combination neoadjuvant therapy with denosumab and nivolumab. The sample size was based on estimated patient numbers available during the study period. The comparison of interest is between the combination neoadjuvant therapy compared to nivolumab alone. Categorical variables will be summarised as frequency and percentage and continuous variables as mean and standard deviation or median and interquartile range. A 95% confidence interval will be reported for primary outcomes. Categorical variables will be examined using the Pearson Chi-squared test or Fisher’s exact test when more than 20% of the expected value are less than 5. Continuous variables will be examined using the Student t-test or Mann-Whitney U test if data is not normally distributed. Paired data will be examined using a paired t-test or repeated measures ANOVA. Kaplan-Meier will be used to estimate progression-free survival and overall survival with the log-rank test used to assess differences between treatments. A Bonferroni correction will be used to adjust for the multiple primary endpoints.
The intention to treat population will be all patients with NSCLC randomized on the study. The as-treated population will be evaluable for toxicity and will include all patients who receive at least one dose of study therapy. After all 30 patients have completed the post-treatment assessment an interim toxicity analysis will be carried out. An interim analysis may also be undertaken for exploratory laboratory investigations on normal and tumour tissue.
Dissemination of results
The study results based on the trial data will be released to the participating physicians, referring physicians, patients and the general medical community. During study close-out, an interim period will be used to complete data collection, following which manuscript(s) based on trial results will be submitted to peer-reviewed journals. Authorship criteria as defined by the International Committee of Medical Journal Editors will be followed.