Venetoclax treatment in patients with cancer has limited impact on circulating T and NK cells.

Venetoclax is an effective treatment for certain blood cancers, such as chronic lymphocytic leukemia (CLL) and acute myeloid leukemia (AML). However, most patients relapse while on venetoclax and further treatment options are limited. Combining venetoclax with immunotherapies is an attractive approach; however, a detailed understanding of how venetoclax treatment impacts normal immune cells in patients is lacking. In this study, we performed deep profiling of peripheral blood (PB) cells from patients with CLL and AML before and after short-term treatment with venetoclax using mass cytometry (cytometry by time of flight) and found no impact on the concentrations of key T-cell subsets or their expression of checkpoint molecules. We also analyzed PB from patients with breast cancer receiving venetoclax long-term using a single-cell multiomics approach (cellular indexing of transcriptomes and epitopes by sequencing) and functional assays. We found significant depletion of B-cell populations with low expression of MCL-1 relative to other immune cells, attended by extensive transcriptomic changes. By contrast, there was less impact on circulating T cells and natural killer (NK) cells, with no changes in their subset composition, transcriptome, or function following venetoclax treatment. Our data indicate that venetoclax has minimal impact on circulating T or NK cells, supporting the rationale of combining this BH3 mimetic drug with cancer immunotherapies for more durable antitumor responses.

PALVEN: phase Ib trial of palbociclib, letrozole and venetoclax in estrogen receptor- and BCL2-positive advanced breast cancer.

The addition of a CDK4/6 inhibitor to endocrine therapy improves progression-free and overall survival in women with metastatic estrogen receptor-positive breast cancer. In that setting, CDK4/6 inhibitors induce a potent cell-cycle arrest (which may be accompanied by tumor senescence) but fail to induce apoptotic cell death. Venetoclax is a potent inhibitor of BCL2, a pro-survival protein overexpressed in the majority of estrogen receptor-positive cancers. Pre-clinical findings indicate that venetoclax augments tumor response to the CDK4/6 inhibitor palbociclib by triggering apoptosis, including in senescent cells. The PALVEN phase Ib trial will further examine this finding. The primary objective is to identify the maximum tolerated dose and determine the recommended phase II dose for palbociclib, letrozole and venetoclax combination therapy. Clinical Trial Registration: NCT03900884 (ClinicalTrials.gov).

The current 'gold standard' treatment for estrogen receptor-positive, HER2-negative metastatic breast cancer is endocrine therapy with a CDK4/6 inhibitor. This combination improves tumor response and patient outcomes, primarily by reducing tumor cell growth. Paradoxically, less killing of tumor cells is observed in the presence of a CDK4/6 inhibitor. The authors hypothesize that co-treatment with venetoclax, an inhibitor of the BCL2 survival protein, will help trigger tumor death, thereby further improving tumor responses and patient outcomes. As a first step, combination therapy comprising letrozole, palbociclib and venetoclax will be tested in a phase I trial to identify the recommended doses for subsequent studies.

Impact of access to novel therapies on the initial management of castrate-resistant prostate cancer: an Australian multicentre study.

BACKGROUND: The impact of regulatory approvals of new therapies for castration-resistant prostate cancer (CRPC) in Australia is unclear. AIMS: To determine if changes in novel therapy access in Australia affected how clinicians initially managed men with newly diagnosed CRPC. METHODS: Data from patients diagnosed with CRPC from 2013 to 2016 across three Australian hospitals were retrospectively collected. Baseline clinicopathological factors and initial management decision at the time of CRPC development (early treatment (ET) vs deferred treatment (DT)) were recorded. Categorical variables between cohorts were compared by Chi-squared analysis. Cox regression analysis was performed to assess the impact of CRPC diagnosis year on time to commencing life-prolonging systemic treatment (TTT). RESULTS: Our study identified 137 CRPC patients, with 126 (92%) patients receiving life-prolonging systemic treatment. The median age was 73 years. The initial management decision was DT in 71 (52%) patients and ET in 66 (48%) patients. There was a significant shift from DT to ET during the study period (2013-2014: DT 61% vs ET 33%; 2015-2016: DT 39% vs ET 67%; P = 0.004), with a rise in novel androgen receptor signalling inhibitor use and simultaneous reduction in first-generation antiandrogen use at CRPC development. Each successive CRPC diagnosis year was associated with shorter TTT on univariate analysis (HR: 1.5, 95% CI: 1.3-1.7, P < 0.001). CONCLUSION: Over time, clinicians are favouring earlier introduction of life-prolonging systemic treatment at the development of CRPC. This trend is largely driven by substantial uptake of novel androgen receptor signalling inhibitors as the preferred initial treatment for CRPC patients.