Eosinophil Peroxidase: A Biomarker for Eosinophilic Chronic Rhinosinusitis Agnostic of Polyp Status

OBJECTIVE

To evaluate eosinophil peroxidase (EPX) as a biomarker for tissue levels of eosinophilia, cytokines, and chemokines within chronic rhinosinusitis (CRS).

METHODS

Twenty-eight subjects undergoing sinonasal surgery were prospectively enrolled. Ethmoid tissue was analyzed with an in-house EPX immunoassay and a 48-plex cytokine-chemokine array. Clinical severity was assessed using SNOT-22 and Lund-Mackay scores. Subjects were grouped as follows: controls, polyp status (CRS with [CRSwNP] and without nasal polyps [CRSsNP]), tissue eosinophilia (eosinophilic CRS [eCRS], non-eosinophilic CRS [neCRS]), or combinations thereof (eCRSwNP, eCRSsNP, neCRSsNP). eCRS was defined as >10 eosinophils per high power field (HPF). Subjects without CRS or asthma were enrolled as controls.

RESULTS

EPX was elevated in CRSwNP compared to control (p = 0.007), in eCRS compared to neCRS (p = 0.002), and in eCRSwNP along with eCRSsNP compared to neCRSsNP (p = 0.023, p = 0.015, respectively). eCRS displayed elevated IL-5 compared to neCRS (p = 0.005). No significant differences in EPX or IL-5 were observed between eCRSwNP and eCRSsNP. IL-5 was elevated in eCRSwNP (p = 0.019) compared neCRSsNP. Area under the receiver operator characteristic curve was 0.938 (95% CI, 0.835-1.00) for EPX and tissue eosinophilia, with an optimal cut-point of 470 ng/mL being 100% specific and 81.25% sensitive for tissue eosinophilia. Linear regression revealed a strong correlation between EPX and IL-5 (R2  = 0.64, p < 0.001). Comparing EPX and IL-5, only EPX displayed significant correlation with SNOT-22 (p = 0.04) and Lund-Mackay score (p = 0.004).

CONCLUSION

EPX is associated with tissue eosinophilia in CRS patients regardless of polyp status. EPX correlates with IL-5 and could be potentially considered a biomarker for anti-IL-5 therapies.

LEVEL OF EVIDENCE

3 Laryngoscope, 134:69-78, 2024.

Germline Genetic Testing in Unselected Squamous and Non-Squamous Head and Neck Cancers

OBJECTIVE

This study describes the prevalence of pathogenic germline variants (PGVs) in head and neck cancer patients, the incremental yield compared to a guideline-based approach to genetic evaluation, and the uptake of family variant testing.

STUDY DESIGN

Prospective cohort study.

SETTING

Three tertiary academic medical centers.

METHODS

Germline sequencing using an 84-gene screening platform among unselected head and neck cancer patients who received care at Mayo Clinic Cancer Centers between April 2018 and March 2020.

RESULTS

Amongst 200 patients, the median age was 62.0 years (Q1, Q3: 55, 71), 23.0% were female, 89.0% white/non-Hispanic, 5.0% Hispanic/Latinx, 6% of another race, and 42.0% had prognostic stage IV disease. The most common subsites were the oropharyngeal (45.0%) and salivary glands (12.0%). The most common histology was squamous cell carcinoma (74.5%). Twenty-one patients (10.5%) had a total of 22 PGVs; 20 of the 21 patients (95.2%) did not meet criteria for testing by current guidelines. Regarding penetrance of the 22 PGVs, 11 were high or moderate (most common PMS2 or HOXB13), and 11 were low or recessive (most common MUTYH, WNR, or RECQL4). One patient had a change in care based on an identified PGV. Family variant testing was completed at a rate of 4.8%.

CONCLUSIONS

Universal gene panel testing identified a PGV in 10.5% of head and neck cancer patients; almost all would have been missed by current guideline-based testing. One of 21 patients had a treatment change due to their PGV, indicating that head and neck cancer treatment decisions are not yet widely informed by germline alterations.

LEVEL OF EVIDENCE

3 Laryngoscope, 133:3378-3388, 2023.

CD38 antibody re-treatment in daratumumab-refractory multiple myeloma after time on other therapies

Monoclonal antibodies targeting CD38 are important for treatment of both newly diagnosed and relapsed multiple myeloma (MM). Daratumumab and isatuximab are anti-CD38 antibodies with the US Food and Drugs Administration approval in multiple different combinations. Despite good initial efficacy, patients inevitably develop drug resistance. Whether patients can be effectively re-treated with these antibodies in subsequent lines of therapy is unclear. Thus far, studies have mostly been limited to clinical retrospectives with short washout periods. To answer whether patients regain sensitivity after longer washouts, we used ex vivo sensitivity testing to isolate the anti-CD38 antibody-specific cytotoxicity in samples obtained from patients who had been exposed to and then off daratumumab for up to 53 months. MM cells from patients who had been off daratumumab for >1 year showed greater sensitivity than those with <1 year, although they still were less sensitive than those who were daratumumab naïve. CD38 expression on MM cells gradually recovered, although, again, not to the level of anti-CD38 antibody-naïve patients. Interestingly, low MM CD38 explained only 45% of cases identified to have daratumumab resistance. With clinical follow-up, we found ex vivo sensitivity predicted subsequent clinical response but CD38 overexpression did not. Patients clinically re-treated with anti-CD38 antibodies had <6 months of clinical benefit, but 1 patient who was daratumumab exposed but not refractory achieved complete response lasting 13 months. We conclude that transient efficacy can be achieved by waiting 1 year before CD38 antibody rechallenge, but this approach may be best used as a bridge to, or after, chimeric antigen receptor T-cell therapy.

PU.1 enforces quiescence and limits hematopoietic stem cell expansion during inflammatory stress

Hematopoietic stem cells (HSCs) are capable of entering the cell cycle to replenish the blood system in response to inflammatory cues; however, excessive proliferation in response to chronic inflammation can lead to either HSC attrition or expansion. The mechanism(s) that limit HSC proliferation and expansion triggered by inflammatory signals are poorly defined. Here, we show that long-term HSCs (HSC^LT) rapidly repress protein synthesis and cell cycle genes following treatment with the proinflammatory cytokine interleukin (IL)-1. This gene program is associated with activation of the transcription factor PU.1 and direct PU.1 binding at repressed target genes. Notably, PU.1 is required to repress cell cycle and protein synthesis genes, and IL-1 exposure triggers aberrant protein synthesis and cell cycle activity in PU.1-deficient HSCs. These features are associated with expansion of phenotypic PU.1-deficient HSCs. Thus, we identify a PU.1-dependent mechanism triggered by innate immune stimulation that limits HSC proliferation and pool size. These findings provide insight into how HSCs maintain homeostasis during inflammatory stress.

Exploiting Protein Translation Dependence in Multiple Myeloma with Omacetaxine-Based Therapy

PURPOSE

The prognosis of patients with multiple myeloma who are resistant to proteasome inhibitors, immunomodulatory drugs (IMiD), and daratumumab is extremely poor. Even B-cell maturation antigen-specific chimeric antigen receptor T-cell therapies provide only a temporary benefit before patients succumb to their disease. In this article, we interrogate the unique sensitivity of multiple myeloma cells to the alternative strategy of blocking protein translation with omacetaxine.

EXPERIMENTAL DESIGN

We determined protein translation levels (n = 17) and sensitivity to omacetaxine (n = 51) of primary multiple myeloma patient samples. Synergy was evaluated between omacetaxine and IMiDs in vitro, ex vivo, and in vivo. Underlying mechanism was investigated via proteomic analysis.

RESULTS

Almost universally, primary patient multiple myeloma cells exhibit >2.5-fold increased rates of protein translation compared with normal marrow cells. Ex vivo treatment with omacetaxine resulted in >50% reduction in viable multiple myeloma cells. In this cohort, high levels of translation serve as a biomarker for patient multiple myeloma cell sensitivity to omacetaxine. Unexpectedly, omacetaxine demonstrated synergy with IMiDs in multiple myeloma cell lines in vitro. In addition, in an IMiD-resistant relapsed patient sample, omacetaxine/IMiD combination treatment resensitized the multiple myeloma cells to the IMiD. Proteomic analysis found that the omacetaxine/IMiD combination treatment produced a double-hit on the IRF4/c-MYC pathway, which is critical to multiple myeloma survival.

CONCLUSIONS

Overall, protein translation inhibitors represent a potential new drug class for myeloma treatment and provide a rationale for conducting clinical trials with omacetaxine alone and in combination with IMiDs for patients with relapsed/refractory multiple myeloma.