Molecular Monitoring as a Path to Cure Acute Promyelocytic Leukemia

Early Endpoints in High-risk Localized Prostate Cancer: Exploratory Analysis of Three Radiation Therapy Oncology Group Phase 3 Studies

BACKGROUND

Early endpoints in clinical trials of high-risk localized prostate cancer (HRLPC) that resemble those monitored in real-world practice could expedite clinical development.

OBJECTIVE

To assess the association of prostate-specific antigen (PSA) recurrence (PSA-R)-based early endpoints with metastasis-free survival (MFS), overall survival (OS), and prostate cancer (PC)-specific survival (PCSS), and to identify clinically undetectable disease.

DESIGN, SETTING, AND PARTICIPANTS

A post hoc analysis of patients with HRLPC from Radiation Therapy Oncology Group studies 9202, 9902, and 0521 was performed.

INTERVENTION

Long-term adjuvant androgen-deprivation therapy (ADT) and post-primary definitive radiotherapy.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Event-free survival (EFS; PSA-R, locoregional recurrence [LRR], distant metastasis [DM], or death), biochemical failure (PSA-R), general clinical failure (PSA-R, LRR, DM, ADT initiation, or death), and no evidence of disease (NED; alive patients without PSA-R, LRR, DM, and subsequent PC therapy, and with testosterone recovery) were assessed for association with MFS, OS, and PCSS using correlation and landmark analyses, Kaplan-Meier method, and Cox proportional-hazard model. PSA-R was defined as PSA nadir + 2 ng/ml; PSA nadir + 2 ng/ml and rising; PSA >5, 10, and 25 ng/ml; or PSA doubling time (PSADT) <6 mo.

RESULTS AND LIMITATIONS

Among assessed early endpoints, EFS with PSA nadir + 2 ng/ml and rising, or with PSA >5 ng/ml was associated with MFS, OS, and PCSS. No development of EFS with PSADT <6 mo or ADT initiation event or achievement of NED at 3 yr was associated with prolonged OS, MFS, and PCSS (hazard ratio [95% confidence interval], 0.53 [0.45-0.64], 0.63 [0.52-0.76], and 0.26 [0.18-0.36], or 0.56 [0.48-0.66], 0.62 [0.52-0.74], and 0.26 [0.19-0.37]) after the landmark time. Older studies performed before the current guidance should be interpreted with caution.

CONCLUSIONS

We identified EFS with PSA nadir + 2 ng/ml and rising, PSA >5 ng/ml, or PSADT <6 mo ± ADT initiation and NED as potentially promising early endpoints in HRLPC that should be validated further.

PATIENT SUMMARY

We identified novel clinical measures that may expedite the development of new medicines for patients with localized prostate cancer at a high risk of progression. These measures, which took into account prostate-specific antigen assessments and other clinical characteristics, should be confirmed in future studies. We also defined a novel measure of no evidence of disease that can help treating physicians identify patients with clinically undetectable disease.

Measurable residual disease after the first consolidation predicts the outcomes of patients with acute promyelocytic leukemia treated with all-trans retinoic acid and chemotherapy

We stratified patients with newly diagnosed acute promyelocytic leukemia (APL) according to a white blood cell (WBC) count of ≥ 3 × 10⁹/L (high risk) or < 3 × 10⁹/L (low risk) before administering risk-adapted chemotherapy in combination with all-trans retinoic acid (ATRA). In total, 27 low-risk and 23 high-risk patients were assigned to receive induction and three courses of consolidation with ATRA and anthracycline, followed by 2-year maintenance regimen. High-risk group additionally received cytarabine during 1st consolidation and another one-shot idarubicin treatment during 3rd consolidation. We prospectively monitored measurable residual disease (MRD) after induction and each consolidation. In the low-risk and high-risk groups, 5-year disease-free survival (DFS) rates were 86.5% and 81.2% (p = 0.862), and 5-year overall survival rates were 100% and 84.8% (p = 0.062), respectively. In the MRD-negative and MRD-positive groups, 5-year DFS rates were 91.7% and 78.4% (p = 0.402) and 84.7% and 60.0% (p = 0.102) after induction and 1st consolidation, respectively. Relapse rates were 8.3% and 13.3% (p = 0.570) and 9.0% and 40.0% (p = 0.076) after induction and 1st consolidation, respectively. Achieving MRD-negativity after 1st consolidation, rather than after induction, was a potential predictor of relapse and DFS in patients with APL treated with ATRA + chemotherapy.

Minimal Residual Disease Status as a Surrogate Endpoint for Progression-free Survival in Newly Diagnosed Multiple Myeloma Studies: A Meta-analysis

BACKGROUND

Therapeutic advances have greatly extended survival times in patients with multiple myeloma, necessitating increasingly lengthy trials when using survival outcomes as primary endpoints. A surrogate endpoint that can more rapidly predict survival could accelerate drug development. We conducted a meta-analysis to evaluate minimal residual disease (MRD) status as a valid progression-free survival (PFS) surrogate in patients with newly diagnosed multiple myeloma (NDMM).

MATERIALS AND METHODS

We searched abstracts in PubMed, The American Society of Hematology, and the European Hematology Association for "myeloma," "minimal residual disease," and "clinical trial." Because of the need to evaluate the treatment effect on MRD response, only randomized studies for subjects with NDMM were included. Details on the MRD-tested populations were required. The meta-analysis was performed by principles outlined at the 2013 United States Food and Drug Administration workshop on MRD in acute myeloid leukemia.⁴² For samples that were not measured for MRD and within the subset specified for MRD assessment, their MRD status was imputed from the samples that had known MRD status. Patients that were excluded from planned MRD assessment were considered MRD-positive.

RESULTS

Six randomized studies, representing 3283 patients and 2208 MRD samples, met analysis inclusion criteria. MRD negativity rates ranged from 0.06 to 0.70. The treatment effect on the odds ratio for MRD-negative response strongly correlated with the hazard ratio for PFS with a coefficient of determination for the weighted regression line of 0.97. Our meta-analysis suggested that MRD status met both the Prentice criteria for PFS surrogacy.

CONCLUSIONS

These results support the claim that MRD status can be used as a surrogate for PFS in NDMM.

Traffic lights for retinoids in oncology: molecular markers of retinoid resistance and sensitivity and their use in the management of cancer differentiation therapy

For decades, retinoids and their synthetic derivatives have been well established anticancer treatments due to their ability to regulate cell growth and induce cell differentiation and apoptosis. Many studies have reported the promising role of retinoids in attaining better outcomes for adult or pediatric patients suffering from several types of cancer, especially acute myeloid leukemia and neuroblastoma. However, even this promising differentiation therapy has some limitations: retinoid toxicity and intrinsic or acquired resistance have been observed in many patients. Therefore, the identification of molecular markers that predict the therapeutic response to retinoid treatment is undoubtedly important for retinoid use in clinical practice. The purpose of this review is to summarize the current knowledge on candidate markers, including both genetic alterations and protein markers, for retinoid resistance and sensitivity in human malignancies.

Evaluating measurable residual disease in acute myeloid leukemia

Mounting evidence indicates that the presence of measurable ("minimal") residual disease (MRD), defined as posttherapy persistence of leukemic cells at levels below morphologic detection, is a strong, independent prognostic marker of increased risk of relapse and shorter survival in patients with acute myeloid leukemia (AML) and can be used to refine risk-stratification and treatment response assessment. Because of the association between MRD and relapse risk, it has been postulated that testing for MRD posttreatment may help guide postremission treatment strategies by identifying high-risk patients who might benefit from preemptive treatment. This strategy, which remains to be formally tested, may be particularly attractive with availability of agents that could be used to specifically eradicate MRD. This review examines current methods of MRD detection, challenges to adopting MRD testing in routine clinical practice, and recent recommendations for MRD testing in AML issued by the European LeukemiaNet MRD Working Party. Inclusion of MRD as an end point in future randomized clinical trials will provide the data needed to move toward standardizing MRD assays and may provide a more accurate assessment of therapeutic efficacy than current morphologic measures.