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	<title>mitomycin C &#8211; Science</title>
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	<title>mitomycin C &#8211; Science</title>
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		<title>Needle Revision Rescues Failing PAUL Glaucoma Implant in a Child</title>
		<link>https://scienmag.com/needle-revision-rescues-failing-paul-glaucoma-implant-in-a-child/</link>
		
		<dc:creator><![CDATA[Ophelia Keating]]></dc:creator>
		<pubDate>Thu, 15 Oct 2026 19:59:06 +0000</pubDate>
				<category><![CDATA[Science News]]></category>
		<category><![CDATA[antifibrotic drug delivery in eye surgery]]></category>
		<category><![CDATA[bleb needling]]></category>
		<category><![CDATA[case report]]></category>
		<category><![CDATA[case study of glaucoma rescue]]></category>
		<category><![CDATA[congenital glaucoma management]]></category>
		<category><![CDATA[encapsulated bleb]]></category>
		<category><![CDATA[glaucoma]]></category>
		<category><![CDATA[glaucoma drainage device]]></category>
		<category><![CDATA[glaucoma implant complications]]></category>
		<category><![CDATA[innovative ophthalmic surgical techniques]]></category>
		<category><![CDATA[intraocular pressure]]></category>
		<category><![CDATA[managing failing glaucoma implants]]></category>
		<category><![CDATA[minimally invasive glaucoma surgery]]></category>
		<category><![CDATA[Minimally invasive surgery]]></category>
		<category><![CDATA[mitomycin C]]></category>
		<category><![CDATA[needle revision]]></category>
		<category><![CDATA[needle revision of glaucoma]]></category>
		<category><![CDATA[non-invasive glaucoma interventions]]></category>
		<category><![CDATA[PAUL glaucoma implant]]></category>
		<category><![CDATA[pediatric glaucoma treatment]]></category>
		<category><![CDATA[pediatric ophthalmology]]></category>
		<category><![CDATA[primary congenital glaucoma]]></category>
		<category><![CDATA[scar tissue removal in glaucoma]]></category>
		<guid isPermaLink="false">https://scienmag.com/?p=277386</guid>

					<description><![CDATA[Surgeons in Saudi Arabia report the first successful needle revision with mitomycin C to rescue a failing PAUL glaucoma implant in a child with primary congenital glaucoma.]]></description>
										<content:encoded><![CDATA[<p>A nine-year-old girl in Riyadh with a lifetime of eye surgeries behind her has become the first reported child to have a failing PAUL glaucoma implant rescued not with a repeat operation, but with a simple needle. Surgeons at the Glaucoma Division of King Khaled Eye Specialist Hospital, working with colleagues from Riyadh Second Health Cluster, used a fine 27-gauge needle to break open the scar capsule that had choked off the implant&#8217;s drainage plate, delivering a carefully dosed antifibrotic drug at the same time. The case, published in Frontiers in Ophthalmology, offers a glimpse of how minimally invasive techniques might spare young patients from yet another round of major surgery.</p>
<p>Primary congenital glaucoma is a rare but relentless disease. Present from birth, it arises when the eye&#8217;s natural drainage structures fail to develop properly, allowing fluid pressure inside the eye to climb to dangerous levels. In children, this pressure does more than threaten the optic nerve; it can physically stretch the growing globe, enlarging the cornea and leaving lasting scars known as Haab striae. Keeping the pressure under control often demands an escalating series of operations over many years, and even then, some eyes stubbornly resist every conventional approach.</p>
<p>When angle surgery and filtration procedures fail, ophthalmologists turn to glaucoma drainage devices, small silicone tubes that shunt excess fluid from the front of the eye to a reservoir, or bleb, beneath the conjunctiva. The PAUL glaucoma implant is one of the newest members of this family. Unlike the valved Ahmed device or the larger non-valved Baerveldt, it features a flexible plate and an ultra-thin tube with a smaller internal diameter, designed to provide controlled aqueous outflow while minimizing trauma to delicate pediatric tissue. Clinical studies have shown encouraging success rates in congenital glaucoma, with pressure control achieved in roughly 67 to 87 percent of eyes at one year after implantation.</p>
<p>But drainage implants share a common Achilles heel: the body&#8217;s own healing response. Aqueous humor is rich in pro-inflammatory signaling molecules, and when it flows into the subconjunctival space, it can trigger an aggressive wound-healing cascade. Fibroblasts multiply, transform into contractile myofibroblasts, and lay down dense extracellular matrix, encasing the implant&#8217;s plate in a thick, low-permeability collagenous shell. Clinicians call this encapsulation, and it behaves like a balloon in a steel jacket: fluid collects but cannot disperse, and the intraocular pressure climbs back up, sometimes dramatically, in what is known as a hypertensive phase.</p>
<p>The patient described in the report had already endured an extraordinary surgical journey. Diagnosed with bilateral primary congenital glaucoma, she underwent deep sclerectomies in both eyes beginning in 2017. When pressure control deteriorated, she received additional procedures on each side: repeat deep sclerectomy in her right eye in 2021 followed by four sessions of micropulse cyclophotocoagulation across 2022 and 2023, and a PAUL implant in 2023. Her left eye followed a similar path, with a second deep sclerectomy in 2024 and implant placement the same year. By the time she presented in 2025, she was juggling three topical medications in one eye, two in the other, and an oral carbonic anhydrase inhibitor, all aimed at holding back pressures that medications alone could no longer master.</p>
<p>On admission, her left eye told the classic story of a failing implant. The pressure measured 27 millimeters of mercury despite maximal therapy. Slit-lamp examination revealed a thick capsule over a well-covered implant plate, and baseline B-scan ultrasonography confirmed a patent tube surrounded by a loculated pocket of trapped fluid, evidence that the device was working but that its outflow reservoir had been sealed off by scar tissue. Her vision held at 20/40, and the optic nerve showed moderate cupping, but the clock was ticking: sustained pressure this high in a child&#8217;s eye risks irreversible damage.</p>
<p>Conventional answers to encapsulation are unsatisfying. Adding more medications rarely defeats the physical barrier of a dense fibrotic shell and can further irritate an already compromised ocular surface. Placing a second implant or turning to cyclophotocoagulation lowers pressure effectively but consumes the limited conjunctival real estate that future surgeries may need. A full surgical revision carries the morbidity of another operation in an eye that has already seen many. Needle revision offers a fourth path: mechanically fenestrate the capsule through the conjunctiva, break the trapped pocket open, and use an antimetabolite such as mitomycin C to suppress the fibrotic response that caused the problem in the first place. The technique has been used in adults for decades, and a 1997 randomized trial showed it outperforming medical therapy for encapsulated blebs, but it had never been reported for a PAUL implant in a child.</p>
<p>Under local anesthesia and sterile conditions, the surgical team localized the encapsulated capsule and began a stepwise needling procedure with a 27-gauge needle. Before puncturing, they injected 0.3 milliliters of mitomycin C at a concentration of 0.4 milligrams per milliliter, mixed with an equal volume of 2 percent lidocaine for comfort, into the sub-Tenon&#8217;s space around the plate. The needle was then advanced through the conjunctiva to disrupt the fibrous wall, and sweeping mechanical debridement with a cotton-tipped applicator helped mobilize the trapped fluid. Subconjunctival dexamethasone was instilled at the end of the procedure, and the eye was dressed with antibiotic-steroid ointment and a protective shield.</p>
<p>The results unfolded rapidly. On the first day after the procedure, the pressure had already fallen from 27 to 24 millimeters of mercury, with the anterior chamber remaining deep and quiet. Nine days later, the eye showed a well-formed, diffuse drainage bleb, and the pressure had dropped into the target range of 14 to 17 millimeters. At six weeks, stabilization was excellent: pressure of 10 millimeters of mercury, vision maintained at 20/40 with isolated letters reaching 20/30, a structurally patent tube, and no inflammation inside the eye. A transient pressure spike to 22 millimeters appeared at the two-month visit, but it settled within days to 13 millimeters. The only wrinkle was a secondary ocular surface problem, superficial punctate keratitis with pinpoint corneal scars, which the team managed successfully with aggressive topical lubrication.</p>
<p>The authors, Abdulrahman Kaki, Jumanah Qedair, Nouf Alzendi, and Konrad Schargel, emphasize that after searching PubMed, Google Scholar, Cochrane, and Web of Science in July 2026, they found no prior report of successful needling of a PAUL implant in a child with primary congenital glaucoma. The case echoes earlier pediatric successes, including a 2020 report in which a 14-year-old boy&#8217;s failed deep sclerectomy was rescued with needle revision plus an antimetabolite, achieving a pressure of 15 millimeters without medications at one year. Together, these cases suggest that needle revision of failed filtering surgeries is a viable, tissue-preserving option in congenital glaucoma, a population in which every remaining square millimeter of healthy conjunctiva matters.</p>
<p>Caution is nonetheless warranted. This was a single case with a follow-up of barely two months, enough to capture the critical early window and the resolution of one transient pressure spike, but not enough to establish long-term durability, sustained pressure control, or late safety. Antifibrotic agents such as mitomycin C carry their own risks, including potential damage to the corneal epithelium and conjunctival wound leaks, and children&#8217;s healing responses can differ substantially from those of adults. The authors themselves call for prospective studies with larger cohorts and extended follow-up before the technique can be considered standard of care.</p>
<p>Still, the message is compelling. For a child whose eye had already absorbed deep sclerectomies, laser treatments, and two drainage implants, a needle and a drop of drug achieved what escalating surgery threatened to require: a rescued device, controlled pressure, preserved vision, and a conjunctiva left intact for whatever the future may hold. As the PAUL implant spreads into pediatric practice worldwide, this report offers surgeons a concrete, conservative playbook for one of its most common failure modes, and it reminds the field that sometimes the least invasive tool, a fine needle wielded with precision, can be the most powerful one on the tray.</p>
<p><strong>Subject of Research:</strong> Needle revision with mitomycin C to treat an encapsulated bleb after PAUL glaucoma implant surgery in a pediatric patient with primary congenital glaucoma</p>
<p><strong>Article Title:</strong> Case Report: Successful needle revision of an encapsulated bleb following PAUL glaucoma Implant surgery in a pediatric patient</p>
<p><strong>Article References:</strong> Kaki, A., Qedair, J., Alzendi, N., &amp; Schargel, K. (2026). Case Report: Successful needle revision of an encapsulated bleb following PAUL glaucoma Implant surgery in a pediatric patient. <em>Frontiers in Ophthalmology, 6</em>, Article 1952678. <a href="https://doi.org/10.3389/fopht.2026.1952678" rel="noopener noreferrer">https://doi.org/10.3389/fopht.2026.1952678</a></p>
<p><strong>Image Credits:</strong> AI Generated</p>
<p><strong>DOI:</strong> <a href="https://doi.org/10.3389/fopht.2026.1952678" rel="noopener noreferrer">10.3389/fopht.2026.1952678</a></p>
<p><strong>Keywords:</strong> glaucoma, PAUL glaucoma implant, primary congenital glaucoma, bleb needling, needle revision, mitomycin C, encapsulated bleb, glaucoma drainage device, pediatric ophthalmology, intraocular pressure, minimally invasive surgery, case report</p>
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		<post-id xmlns="com-wordpress:feed-additions:1">277386</post-id>	</item>
		<item>
		<title>Forest soil viruses may dampen how strongly microbes respire as temperatures rise</title>
		<link>https://scienmag.com/forest-soil-viruses-may-dampen-how-strongly-microbes-respire-as-temperatures-rise/</link>
		
		<dc:creator><![CDATA[Alan Morgan]]></dc:creator>
		<pubDate>Fri, 25 Sep 2026 21:54:40 +0000</pubDate>
				<category><![CDATA[Agriculture]]></category>
		<category><![CDATA[bacterial life-history strategies]]></category>
		<category><![CDATA[bacteriophages]]></category>
		<category><![CDATA[bacteriophages in soil]]></category>
		<category><![CDATA[carbon cycle]]></category>
		<category><![CDATA[climate change and soil carbon release]]></category>
		<category><![CDATA[climate gradient]]></category>
		<category><![CDATA[climate warming]]></category>
		<category><![CDATA[forest soil viruses]]></category>
		<category><![CDATA[forest soils]]></category>
		<category><![CDATA[impact of viruses on forest soil health]]></category>
		<category><![CDATA[lysogenic viral relationships]]></category>
		<category><![CDATA[lysogeny]]></category>
		<category><![CDATA[microbial respiration]]></category>
		<category><![CDATA[microbial respiration in forests]]></category>
		<category><![CDATA[mitomycin C]]></category>
		<category><![CDATA[Q10]]></category>
		<category><![CDATA[soil microbial community dynamics]]></category>
		<category><![CDATA[soil viruses]]></category>
		<category><![CDATA[temperature sensitivity]]></category>
		<category><![CDATA[temperature sensitivity of soil microbes]]></category>
		<category><![CDATA[viral influence on carbon flux]]></category>
		<category><![CDATA[viral lysis and lysogeny]]></category>
		<category><![CDATA[viral modulation of microbial activity]]></category>
		<category><![CDATA[viral roles in greenhouse gas emissions]]></category>
		<guid isPermaLink="false">https://scienmag.com/?p=214786</guid>

					<description><![CDATA[A study across a 3,600-kilometer climate gradient in China links lysogenic viral processes in forest soils to a reduced temperature sensitivity of microbial respiration, suggesting viruses may moderate carbon losses under warming.]]></description>
										<content:encoded><![CDATA[<p>Beneath every forest floor, an invisible war and an uneasy truce unfold simultaneously. Bacteriophages, the viruses that infect soil bacteria, can rupture their hosts in a burst of viral replication, or they can quietly integrate their genomes into bacterial chromosomes and ride along as dormant passengers, a state known as lysogeny. While viral lysis has long been appreciated as a shaper of microbial communities, the role of these lysogenic relationships in one of the planet&#8217;s most consequential carbon fluxes, the microbial respiration of forest soils, has remained largely unexplored. A new study published in Plant and Soil now links lysogenic viral processes to a striking pattern: a reduced temperature sensitivity of microbial respiration across forests spanning an enormous climatic range.</p>
<p>The research, led by Jia Yao and Ming Nie of Fudan University in Shanghai, together with colleagues, tackled a question with direct implications for climate modeling. Soil microbial respiration releases carbon dioxide as microbes metabolize organic matter, and the rate of that release accelerates as temperatures rise. The magnitude of this acceleration is captured by the temperature sensitivity coefficient, or Q10, which describes how much respiration increases for every ten degrees Celsius of warming. Whether Q10 varies systematically across climates, and what biological mechanisms drive that variation, remains one of the more contested issues in terrestrial carbon cycle science, with direct consequences for how strongly soils are expected to feed back into atmospheric warming.</p>
<p>To probe the role of lysogenic viruses, the team collected soils from 13 forest sites distributed along a 3,600-kilometer latitudinal climate gradient across China, from cool northern forests to warm subtropical ones. In the laboratory, they incubated each soil at three temperatures, 15, 25, and 35 degrees Celsius, and measured microbial respiration. Crucially, they also employed a chemical trick that has become a standard tool in viral ecology: treatment with mitomycin C, a compound that damages bacterial DNA and thereby provokes temperate prophages harbored within bacterial genomes to enter the lytic cycle. The response of a soil community to mitomycin C induction serves as an operational proxy for the abundance and activity of lysogenic viral processes in that community.</p>
<p>The design allowed the researchers to construct three distinct estimates of thermal sensitivity. Soils treated with mitomycin C exhibited higher Q10 values than untreated controls, indicating that chemically forcing prophages out of their lysogenic state intensified the temperature response of respiration. More intriguing was a third quantity: the Q10 calculated from the contrast between induced and uninduced soils, which the authors interpret as an SLV-associated Q10, reflecting the thermal behavior of respiration linked to lysogenic viral processes. This proxy-derived sensitivity was the lowest of the three, suggesting that processes tied to lysogenic viruses are associated with a dampened apparent response of respiration to warming.</p>
<p>Across the 13 sites, the variation in this SLV-associated temperature sensitivity was most strongly associated with two characteristics of the bacterial communities: their abundance and their life-history strategies. Soil bacteria are commonly sorted along a spectrum from r-strategists, which grow rapidly and opportunistically when resources are plentiful, to K-strategists, which invest in persistence, resource efficiency, and stress tolerance under more competitive conditions. Previous work has shown that the dominance of one strategy or the other shapes how microbial respiration responds to temperature, and the new findings indicate that the viral induction response is entangled with this same axis of microbial life history. Communities where lysogenic processes left a distinct imprint on respiration were also communities whose compositional and functional makeup reflected particular positions along the r-to-K spectrum.</p>
<p>Climate itself did not disappear from the picture, but its influence was largely indirect. The researchers used structural equation modeling, a statistical framework that allows direct and indirect pathways among variables to be separated, to trace how climatic variables propagate to the viral-linked temperature sensitivity. The analysis revealed that climate was connected to the SLV-associated Q10 through mediating factors, chiefly soil pH and the physical properties of the soil, such as texture-related characteristics. This pattern is consistent with a growing body of viral ecology showing that soil pH is a powerful determinant of viral community structure at scales from local plots to the globe. In other words, climate appears to set the stage, through the chemical and physical environment it helps create, on which lysogenic viral processes and bacterial life-history traits together govern how temperature-sensitive respiration becomes.</p>
<p>The geographic pattern embedded in these results is especially noteworthy. The association between the mitomycin C response and reduced apparent thermal sensitivity was strongest in warmer forest soils, implying that in the very ecosystems where microbial respiration could potentially release the most additional carbon under continued warming, lysogenic viral processes may be exerting a moderating influence. The authors are careful with their language throughout, framing the findings in terms of association rather than proof of causation. Mitomycin C induction is a blunt instrument: the compound is a DNA-damaging agent, and the observed differences between treated and untreated soils could in principle reflect the combined consequences of prophage induction, bacterial mortality, altered community composition, and the release of cellular contents. The interpretation of the induced contrast as an SLV-associated signal is therefore an operational one, a proxy rather than a direct measurement of viral behavior.</p>
<p>Even so, the study lands at a moment when the viral dimension of soil carbon cycling is moving rapidly from the margins to the mainstream. A global atlas of soil viruses published in 2024 catalogued an enormous and previously uncharted viral diversity and flagged potential biogeochemical impacts, while other recent work has demonstrated that viral lysis can alleviate microbial nutrient limitation and accumulate chemically recalcitrant dissolved organic matter in soils. Theoretical treatments have argued that viral infections likely mediate microbial controls on ecosystem responses to warming, but empirical tests along real climate gradients have been scarce. By combining a standardized induction assay with controlled incubations across thousands of kilometers, the new study offers one of the more systematic empirical links to date between a specific viral strategy and a keystone carbon-cycle parameter.</p>
<p>The mechanistic possibilities behind the observed pattern remain open. Lysogeny can benefit bacterial hosts directly: cryptic prophages can confer tolerance to environmental stress, and integrating viruses may alter host metabolism in ways that change growth rates and resource use. If lysogeny is more prevalent or more consequential in warm, low-latitude soils, and if it favors or co-occurs with K-strategist lineages whose respiration is inherently less temperature responsive, then the dampened SLV-associated Q10 would follow as an emergent property of the host-virus ecosystem. Alternatively, the induction treatment itself may reveal the scale of the lysogenic reservoir, with soils harboring more temperate phages showing different post-induction respiratory trajectories. Distinguishing among these mechanisms will require experiments that go beyond induction proxies, perhaps tracking viral and host population dynamics through time under warming.</p>
<p>For climate modelers, the message is both cautionary and constructive. The findings suggest that bacterial responses associated with lysogenic viral processes deserve a place in future assessments of how forest soil carbon responds to warming, particularly when evaluating microbial controls on carbon turnover. If lysogeny-associated processes genuinely reduce the thermal sensitivity of respiration in warmer forests, then current projections that ignore viral regulation may overestimate carbon losses from those systems. But because the evidence is associative and proxy-based, the authors&#8217; conclusions point less toward immediate model revision and more toward an agenda: combining induction experiments with viromics, microbial trait measurements, and gradient sampling to pin down when, where, and how the quiet passengers in bacterial genomes bend the temperature curve of one of Earth&#8217;s largest carbon fluxes. The forest floor, it turns out, is not merely a chemical reactor warmed by the atmosphere above; it is also an arena where viruses, hosts, and climate quietly negotiate the pace of carbon&#8217;s return to the sky.</p>
<p><strong>Subject of Research:</strong> Association between lysogenic soil viruses and the temperature sensitivity of forest soil microbial respiration</p>
<p><strong>Article Title:</strong> Lysogenic viral processes are associated with reduced temperature sensitivity of forest soil microbial respiration</p>
<p><strong>Article References:</strong> Yao, J., Xu, J., Xu, X., Liu, M., Chen, C., Bao, Y., Li, J., &amp; Nie, M. (2026). Lysogenic viral processes are associated with reduced temperature sensitivity of forest soil microbial respiration. <em>Plant and Soil</em>. <a href="https://doi.org/10.1007/s11104-026-09126-x" rel="noopener noreferrer">https://doi.org/10.1007/s11104-026-09126-x</a></p>
<p><strong>Image Credits:</strong> AI Generated</p>
<p><strong>DOI:</strong> <a href="https://doi.org/10.1007/s11104-026-09126-x" rel="noopener noreferrer">10.1007/s11104-026-09126-x</a></p>
<p><strong>Keywords:</strong> lysogeny, soil viruses, bacteriophages, forest soils, microbial respiration, temperature sensitivity, Q10, carbon cycle, climate gradient, mitomycin C, bacterial life-history strategies, climate warming</p>
]]></content:encoded>
					
		
		
		<post-id xmlns="com-wordpress:feed-additions:1">214786</post-id>	</item>
		<item>
		<title>ATR Inhibitors Supercharge Bladder Cancer Chemotherapy in Patient-Derived Organoids</title>
		<link>https://scienmag.com/atr-inhibitors-supercharge-bladder-cancer-chemotherapy-in-patient-derived-organoids/</link>
		
		<dc:creator><![CDATA[Nathaniel Bowman]]></dc:creator>
		<pubDate>Sat, 12 Sep 2026 17:16:35 +0000</pubDate>
				<category><![CDATA[Cancer]]></category>
		<category><![CDATA[ATR inhibitors]]></category>
		<category><![CDATA[ATR kinase inhibitors]]></category>
		<category><![CDATA[berzosertib]]></category>
		<category><![CDATA[bladder cancer]]></category>
		<category><![CDATA[bladder cancer recurrence prevention]]></category>
		<category><![CDATA[bladder cancer treatment]]></category>
		<category><![CDATA[cancer cell survival mechanisms]]></category>
		<category><![CDATA[cancer recurrence]]></category>
		<category><![CDATA[ceralasertib]]></category>
		<category><![CDATA[combination therapy for bladder cancer]]></category>
		<category><![CDATA[DNA damage response]]></category>
		<category><![CDATA[DNA repair enzyme targeting]]></category>
		<category><![CDATA[drug synergy]]></category>
		<category><![CDATA[improving bladder cancer chemotherapy outcomes]]></category>
		<category><![CDATA[intravesical chemotherapy]]></category>
		<category><![CDATA[intravesical chemotherapy enhancement]]></category>
		<category><![CDATA[mitomycin C]]></category>
		<category><![CDATA[Non-Muscle Invasive Bladder Cancer]]></category>
		<category><![CDATA[patient-derived bladder cancer organoids]]></category>
		<category><![CDATA[patient-derived organoids]]></category>
		<category><![CDATA[personalized bladder cancer models]]></category>
		<category><![CDATA[tuvusertib]]></category>
		<guid isPermaLink="false">https://scienmag.com/?p=196887</guid>

					<description><![CDATA[Dutch researchers have shown that combining the bladder chemotherapy drug mitomycin C with ATR kinase inhibitors eradicates patient-derived non-muscle invasive bladder cancer organoids and prevents their regrowth for six weeks.]]></description>
										<content:encoded><![CDATA[<p>Non-muscle invasive bladder cancer is one of the most common cancers in the developed world, and although it is caught early in most patients, it has an uncomfortable habit of coming back. Standard treatment involves surgically removing visible tumours and then flushing the bladder with chemotherapy drugs such as mitomycin C, or with the live bacterium BCG, in an attempt to destroy any malignant cells left behind. Yet despite these efforts, a large proportion of patients experience recurrence, and some progress to muscle-invasive disease that requires far more aggressive therapy. Researchers at University Medical Center Utrecht in the Netherlands now report a strategy that could dramatically improve those odds, showing in laboratory models built directly from patient tumours that pairing intravesical chemotherapy with drugs that disable a key DNA repair enzyme can wipe out cancer cells that would otherwise survive and regrow.</p>
<p>The new study, published in the British Journal of Cancer, focuses on a kinase called ATR, short for ataxia telangiectasia and Rad3-related protein. ATR sits at the heart of the cellular response to replication stress, the potentially lethal situation in which the molecular machinery that copies DNA stalls or breaks down. When chemotherapy drugs such as mitomycin C damage DNA, dividing cells rely heavily on ATR signalling to pause the cell cycle, stabilise stalled replication forks and coordinate repair. Block ATR pharmacologically, and cells exposed to DNA-damaging agents lose their safety net: replication forks collapse, DNA double-strand breaks accumulate, and the cell is pushed toward catastrophe. This concept, often described as exploiting a vulnerability created by the tumour&#8217;s own dependence on DNA damage checkpoints, has already shown promise in clinical trials of ATR inhibitors such as berzosertib in combination with platinum chemotherapy for advanced solid tumours.</p>
<p>What makes the Utrecht study distinctive is its model system. Rather than relying on immortalised cancer cell lines grown in two dimensions, which often fail to capture the biology of real tumours, the team used patient-derived organoids, miniature three-dimensional tumour cultures grown from tissue of six patients with non-muscle invasive bladder cancer. Organoids preserve many of the genetic and molecular features of the original tumours, including the expression of urothelial carcinoma markers, making them a far more faithful testing ground for new drug combinations. The researchers confirmed that their organoid lines expressed characteristic bladder cancer markers, validating them as genuine representatives of the disease they were designed to model.</p>
<p>The experimental design cleverly mimicked clinical practice. In patients, mitomycin C is delivered directly into the bladder as an instillation that remains in contact with the tumour tissue for roughly one to two hours before being drained. The researchers therefore exposed the organoids to mitomycin C for just two hours, replicating the transient exposure that tumour cells experience in the bladder, and only afterwards did they add ATR inhibitors, which the cells encountered for a prolonged 72-hour period. Three clinically relevant ATR inhibitors were tested: berzosertib, ceralasertib and tuvusertib, all of which have entered clinical trials in various cancers. The team also examined combinations with gemcitabine and epirubicin, two further agents used in intravesical chemotherapy regimens, in one organoid line.</p>
<p>The results were striking. Organoids treated with mitomycin C alone, or with an ATR inhibitor alone, eventually recovered: when the researchers followed the cultures for six weeks after treatment, the surviving cells proliferated at rates similar to untreated controls, demonstrating that neither agent on its own could eliminate the tumour cell population. In sharp contrast, organoids that received the sequential combination of mitomycin C followed by an ATR inhibitor showed severely impaired viability, and crucially, this effect persisted throughout the six-week observation period. The combination did not merely slow the cancer cells down; it appeared to destroy their capacity to regrow, which is precisely the property needed for a therapy intended to prevent recurrence after tumour resection.</p>
<p>Delving into the mechanism, the researchers showed that berzosertib potently suppressed the ATR signalling that mitomycin C normally triggers. DNA damage induced by the chemotherapy was marked by phosphorylated H2AX, a well-established molecular beacon of DNA double-strand breaks, and blocking ATR prevented the checkpoint response that would normally allow cells to survive this damage. Consistent with catastrophic, irreparable DNA damage, the combination treatment drove the organoid cells into apoptosis, the controlled programme of cell death. Quantitative analysis of the drug interaction using synergy scoring frameworks confirmed that the effect was genuinely synergistic rather than merely additive, meaning the two drugs together killed far more cells than would be predicted from their individual activities.</p>
<p>The implications for patients are considerable. Recurrence after intravesical therapy remains the central clinical challenge in non-muscle invasive bladder cancer, driving repeated surgeries, lifelong surveillance and, in a substantial minority of cases, progression to life-threatening muscle-invasive disease. The economic burden of bladder cancer across Europe is among the highest of any malignancy, largely because of the intensity of monitoring and repeat treatment that recurrence entails. A regimen that converts transient chemotherapy exposure into durable eradication of residual tumour cells could reduce recurrence rates, spare patients repeated interventions and delay or prevent progression. Because ATR inhibitors such as berzosertib, ceralasertib and tuvusertib are already in clinical development, the path from laboratory finding to clinical testing is shorter than for an entirely novel drug class.</p>
<p>There are important caveats. The study is preclinical, conducted in organoids rather than in patients, and although organoids are among the most clinically predictive laboratory models available, they cannot fully reproduce the immune system, the bladder wall architecture or the complex urine environment that shapes drug activity in vivo. The number of organoid lines tested, six for the mitomycin C combinations, is modest, and the gemcitabine and epirubicin experiments were limited to a single line, so the generality of the synergy across the molecular diversity of bladder cancer remains to be established. Questions also remain about the optimal sequencing, dosing and delivery of ATR inhibitors in the bladder, and about whether systemic administration would be needed or whether the inhibitors could themselves be delivered intravesically to limit side effects.</p>
<p>Nevertheless, the study provides a compelling proof of principle that the DNA damage response is a druggable Achilles heel of non-muscle invasive bladder cancer, and it establishes patient-derived organoids as a practical platform for optimising intravesical combination therapies before they are tested in the clinic. The findings build on a growing body of evidence that ATR inhibition sensitises bladder tumours to DNA-targeted agents, including earlier work showing enhanced cisplatin and gemcitabine activity in bladder cancer cell lines and clinical trial data combining berzosertib with platinum chemotherapy in advanced urothelial carcinoma. If the synergy observed in these miniature tumours translates to patients, the humble bladder instillation, a treatment whose basic design has changed little in decades, could be transformed into a precision strike that leaves behind not just damaged cancer cells, but none at all.</p>
<p><strong>Subject of Research:</strong> Combining ATR kinase inhibitors with intravesical chemotherapy to prevent recurrence in non-muscle invasive bladder cancer, tested in patient-derived organoids.</p>
<p><strong>Article Title:</strong> ATR inhibitors synergise with mitomycin C to enhance cytotoxicity in patient-derived non-muscle invasive bladder cancer organoids</p>
<p><strong>Article References:</strong> Zuidema, A., Nijland, L., van Megesen, K., Vosjan, M. M., Viergever, B. J., Kranenburg, O., &amp; Meijer, R. P. (2026). ATR inhibitors synergise with mitomycin C to enhance cytotoxicity in patient-derived non-muscle invasive bladder cancer organoids. <em>British Journal of Cancer</em>. <a href="https://doi.org/10.1038/s41416-026-03581-0" rel="noopener noreferrer">https://doi.org/10.1038/s41416-026-03581-0</a></p>
<p><strong>Image Credits:</strong> AI Generated</p>
<p><strong>DOI:</strong> <a href="https://doi.org/10.1038/s41416-026-03581-0" rel="noopener noreferrer">10.1038/s41416-026-03581-0</a></p>
<p><strong>Keywords:</strong> bladder cancer, ATR inhibitors, mitomycin C, patient-derived organoids, DNA damage response, non-muscle invasive bladder cancer, berzosertib, ceralasertib, tuvusertib, intravesical chemotherapy, drug synergy, cancer recurrence</p>
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