Biosafety and biohazard considerations of HSV-1-based oncolytic viral immunotherapy.

Oncolytic viral immunotherapies are agents which can directly kill tumor cells and activate an immune response. Oncolytic viruses (OVs) range from native/unmodified viruses to genetically modified, attenuated viruses with the capacity to preferentially replicate in and kill tumors, leaving normal tissue unharmed. Talimogene laherparepvec (T-VEC) is the only OV approved for patient use in the United States; however, during the last 20 years, there have been a substantial number of clinical trials using OV immunotherapies across a broad range of cancers. Like T-VEC, many OV immunotherapies in clinical development are based on the herpes simplex virus type 1 (HSV-1), with genetic modifications for tumor selectivity, safety, and immunogenicity. Despite these modifications, HSV-1 OV immunotherapies are often treated with the same biosafety guidelines as the wild-type virus, potentially leading to reduced patient access and logistical hurdles for treatment centers, including community treatment centers and small group or private practices, and healthcare workers. Despite the lack of real-world evidence documenting possible transmission to close contacts, and in the setting of shedding and biodistribution analyses for T-VEC demonstrating limited infectivity and low risk of spread to healthcare workers, barriers to treatment with OV immunotherapies remain. With comprehensive information and educational programs, our hope is that updated biosafety guidance on OV immunotherapies will reduce logistical hurdles to ensure that patients have access to these innovative and potentially life-saving medicines across treatment settings. This work reviews a comprehensive collection of data in conjunction with the opinions of the authors based on their clinical experience to provide the suggested framework and key considerations for implementing biosafety protocols for OV immunotherapies, namely T-VEC, the only approved agent to date

Biosafety and biohazard considerations of HSV-1–based oncolytic viral immunotherapy

Oncolytic viral immunotherapies are agents which can directly kill tumor cells and activate an immune response. Oncolytic viruses (OVs) range from native/unmodified viruses to genetically modified, attenuated viruses with the capacity to preferentially replicate in and kill tumors, leaving normal tissue unharmed. Talimogene laherparepvec (T-VEC) is the only OV approved for patient use in the United States; however, during the last 20 years, there have been a substantial number of clinical trials using OV immunotherapies across a broad range of cancers. Like T-VEC, many OV immunotherapies in clinical development are based on the herpes simplex virus type 1 (HSV-1), with genetic modifications for tumor selectivity, safety, and immunogenicity. Despite these modifications, HSV-1 OV immunotherapies are often treated with the same biosafety guidelines as the wild-type virus, potentially leading to reduced patient access and logistical hurdles for treatment centers, including community treatment centers and small group or private practices, and healthcare workers. Despite the lack of real-world evidence documenting possible transmission to close contacts, and in the setting of shedding and biodistribution analyses for T-VEC demonstrating limited infectivity and low risk of spread to healthcare workers, barriers to treatment with OV immunotherapies remain. With comprehensive information and educational programs, our hope is that updated biosafety guidance on OV immunotherapies will reduce logistical hurdles to ensure that patients have access to these innovative and potentially life-saving medicines across treatment settings. This work reviews a comprehensive collection of data in conjunction with the opinions of the authors based on their clinical experience to provide the suggested framework and key considerations for implementing biosafety protocols for OV immunotherapies, namely T-VEC, the only approved agent to date

Depletion of Deoxyribonucleotide Pools is an Endogenous Source of DNA Damage in Cells Undergoing Oncogene-Induced Senescence

In normal human cells, oncogene-induced senescence (OIS) depends on induction of DNA damage response (DDR). Oxidative stress and hyper-replication of genomic DNA have been proposed as major causes of DNA damage in OIS cells. Here we report that down-regulation of deoxyribonucleoside pools is another endogenous source of DNA damage in normal human fibroblasts (NHF) undergoing HRAS[superscript G12V]-induced senescence. NHF-HRAS[superscript G12V] cells under-expressed thymidylate synthase (TS) and ribonucleotide reductase (RR), two enzymes required for the entire de novo deoxyribonucleotide biosynthesis, and possessed low dNTP levels. Chromatin at the promoters of the genes encoding TS and RR was enriched with RB tumor suppressor protein and histone H3 tri-methylated at lysine 9. Importantly, ectopic co-expression of TS and RR or addition of deoxyribonucleosides substantially suppressed DNA damage, senescence-associated phenotypes and proliferation arrest in two types of NHF expressing HRAS[superscript G12V]. Reciprocally, shRNA-mediated suppression of TS and RR caused DNA damage and senescence in NHF although less efficiently than HRAS[superscript G12V]. However, overexpression of TS and RR in quiescent NHF did not overcome proliferation arrest, suggesting that unlike quiescence, OIS requires depletion of dNTP pools and activated DNA replication. Our data identify a previously unknown role of deoxyribonucleotides in regulation of oncogene-induced senescence.This is the author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/the-american-journal-of-pathology/

Ribonucleotide reductase and thymidylate synthase or exogenous deoxyribonucleosides reduce DNA damage and senescence caused by C‐MYC depletion

The down‐regulation of dominant oncogenes, including C‐MYC, in tumor cells often leads to the induction of senescence via mechanisms that are not completely identified. In the current study, we demonstrate that MYC‐depleted melanoma cells undergo extensive DNA damage that is caused by the underexpression of thymidylate synthase (TS) and ribonucleotide reductase (RR) and subsequent depletion of deoxyribonucleoside triphosphate pools. Simultaneous genetic inhibition of TS and RR in melanoma cells induced DNA damage and senescence phenotypes very similar to the ones caused by MYC‐depletion. Reciprocally, overexpression of TS and RR in melanoma cells or addition of deoxyribonucleosides to culture media substantially inhibited DNA damage and senescence‐associated phenotypes caused by C‐MYC depletion. Our data demonstrate the essential role of TS and RR in C‐MYC‐dependent suppression of senescence in melanoma cells.Keywords: ribonucleotide reductase, oncogene‐induced senescence, dNTP, myc, melanoma, thymidylate synthas

Sentinel lymph node biopsy in periocular merkel cell carcinoma: a case report

Abstract Background The National Comprehensive Cancer Network guidelines for Merkel cell carcinoma recommend performance of the sentinel lymph node biopsy in all patients with clinically negative nodal disease for staging and treatment. Nevertheless, sentinel lymph node biopsy in the periocular region is debated as tumors are typically smaller and lymphatic variability can make performance procedurally problematic. Case presentation We present a case of a Caucasian patient in their seventies who presented with a 1.0 cm periocular Merkel cell carcinoma, who underwent Mohs surgery with a Tenzel flap repair, that was found to have a positive sentinel lymph node biopsy, but who, despite parotidectomy, selective neck dissection, and radiation, succumbed to the disease. Conclusions Evidence in both the site-specific and non-specific literature demonstrates: (1) Worsening prognosis with extent of lymph node burden, (2) improvements in our abilities to perform lymphoscintigraphy, (3) locoregional and distant metastatic disease in patients with tumor sizes ≤1 cm, and (4) significant rates of sentinel lymph node positivity in patients with tumor sizes ≤1 cm. Our case supports that sentinel lymph node biopsy should be considered in all clinically nodal negative periocular Merkel cell carcinoma, regardless of size, and despite limited site-specific studies on the subject

The palliative role of lasers in the treatment of melanoma

Melanoma, accounting for a significant proportion of skin cancer-related deaths, has variable survival outcomes based on the stage at diagnosis and treatment efficacy. Traditional treatments, while effective, pose risks of scarring and systemic side effects. Laser therapy offers an emerging non-surgical alternative, with CO2 lasers particularly showing promise in palliative care. A comprehensive search was conducted using PubMed, focusing on laser therapy for melanoma treatment. The search included studies on both stand-alone and adjunct laser therapies, with inclusion criteria requiring peer-reviewed articles detailing treatment outcomes for primary, recurrent, or metastatic melanoma. The literature shows that laser therapy for melanoma falls into four major types when categorized by laser medium: solid-state, diode, pulse-dye, and gas (CO2). Data on solid-state lasers for melanoma are limited and their use remains controversial. However, one study with high-energy pulsed neodymium lasers reported a 5-year survival of 82.9% with minimal adverse effects for primary melanoma. CO2 laser therapy has been effective for palliative treatment, with one study showing 54.8% of patients with recurrent melanoma surviving 5.4 years post-ablation. For metastatic melanoma, numerous studies have shown that CO2 laser therapy can provide symptomatic relief and disease control. Combination therapies using lasers and immune-based therapies have demonstrated enhanced outcomes and immune activation, highlighting the potential of laser therapies in melanoma management. While traditional treatments remain the standard for primary melanoma, laser therapies, particularly CO2 laser ablation, show substantial promise in palliative care for metastatic melanoma. Careful patient selection and assessment are crucial for achieving positive outcomes