Cytarabine

證據等級: L5

預測適應症: 10 個

Cytarabine: From Acute Leukemia to Small Cell Lung Carcinoma

One-Sentence Summary

Cytarabine (Ara-C) is a well-established S-phase–specific antimetabolite, classically used in the treatment of acute leukemias and high-dose lymphoma conditioning regimens. The TxGNN model predicts it may be effective for Small Cell Lung Carcinoma (SCLC), supported by 20 publications — though the most directly relevant clinical evidence dates from the 1970s–1990s, and the 3 retrieved clinical trials are only indirectly related. Overall evidence is rated L3, reflecting historical observational and phase II data rather than modern controlled trials.

Quick Overview

Item	Content
Original Indication	Acute leukemia (established clinical use; not registered in Singapore)
Predicted New Indication	Small Cell Lung Carcinoma
TxGNN Prediction Score	99.78%
Evidence Level	L3
Singapore Market Status	Not marketed
Number of Registrations	0
Recommended Decision	Hold

Why is This Prediction Reasonable?

Cytarabine (cytosine arabinoside, Ara-C) is a pyrimidine antimetabolite that competitively inhibits DNA polymerase by substituting for deoxycytidine triphosphate during DNA replication. Because it acts specifically during S phase, it is most potent against tumours with a high proportion of actively dividing cells — precisely the biological profile of small cell lung carcinoma.

SCLC is one of the most rapidly proliferating solid tumours known, with extremely high S-phase fractions and doubling times measured in days rather than weeks. This biological overlap with classical Ara-C targets — acute leukaemias — forms the mechanistic backbone of the TxGNN prediction, and was indeed recognised by oncologists in the 1970s and 1980s. Several early clinical series combined Ara-C with cisplatin, cyclophosphamide, or etoposide in SCLC, reporting partial remissions. One multicentre study of 20 untreated SCLC patients achieved a 78% combined response rate with a cyclophosphamide/Adriamycin/Ara-C regimen plus radiotherapy (PMID 232239).

Despite this early promise, the platinum/etoposide doublet ultimately became the standard of care for SCLC due to superior reproducibility and tolerability, displacing Ara-C–based regimens from mainstream practice. The most defensible contemporary role for Cytarabine in SCLC is intrathecal administration for leptomeningeal metastasis — an established use in haematological malignancies that has been extrapolated to solid-tumour CNS complications — and potentially in refractory or multiply relapsed settings where conventional options are exhausted.

Clinical Trial Evidence

Note: All three retrieved trials have Grade C (indirect) relevance. They study Pemetrexed — not Cytarabine — as the primary intrathecal agent for NSCLC leptomeningeal metastases, or adjuvant regimens in early NSCLC without SCLC-specific endpoints. No prospective trial directly evaluating Cytarabine in SCLC was identified in the current search.

Trial Number	Phase	Status	Enrollment	Key Findings
NCT03101579	Phase 1	Completed	13	Intrathecal pemetrexed for recurrent NSCLC leptomeningeal metastases; Cytarabine cited as one of the current standard IT agents, providing background context for IT chemotherapy design in thoracic oncology
NCT03507244	Phase 1/2	Completed	34	IT pemetrexed + involved-field radiotherapy for LM from solid tumours; offers a reference treatment design framework for CNS-directed chemotherapy in lung cancer
NCT00863512	Phase 3	Terminated	34	Adjuvant chemotherapy (vinorelbine, cisplatin, docetaxel, gemcitabine, pemetrexed) in early NSCLC; terminated early due to slow accrual; no SCLC arms, no Cytarabine — low reference value

Literature Evidence

Prioritised by direct relevance to Cytarabine in SCLC or lung cancer, then by study design tier:

PMID	Year	Type	Journal	Key Findings
232239	1979	Clinical Series	Med Pediatr Oncol	20 untreated SCLC patients received cyclophosphamide + Adriamycin + cytosine arabinoside q28d + radiotherapy; 78% combined response rate, median survival 49+ weeks for complete responders — earliest direct evidence for Ara-C in SCLC
6095640	1984	Clinical Study	Am J Clin Oncol	Continuous-infusion Ara-C (100 mg/m²/d) in SCLC: no responses in 10 heavily pre-treated patients (monotherapy); Ara-C added to CAV in 25 extensive-stage patients with evaluation of additive benefit
2841844	1988	Clinical Study	Am J Clin Oncol	VP-16 + infusional Ara-C (45 mg/m²/d × 72 h) in 17 SCLC patients refractory to combination chemotherapy; limited objective responses, 3 early deaths from progressive disease
9363869	1997	RCT	J Clin Oncol	Randomised trial of chemo + radiation ± warfarin in limited-stage SCLC (CALGB); provides a benchmark for multimodality regimens in limited-stage disease — comparator context for historic Ara-C combinations
6264785	1981	Case Series	Am J Med	Meningeal carcinomatosis in SCLC: 60 patients, intensive systemic chemotherapy without prophylactic cranial irradiation; 78% overall response rate, supports relevance of Cytarabine in CNS complication management
28223673	2017	Case Report	Gan To Kagaku Ryoho	SCLC (Stage IV) with meningeal carcinomatosis effectively managed with multidisciplinary approach including IT chemotherapy; illustrates a contemporary clinical scenario where IT Cytarabine remains an active option
2157307	1990	Phase II	Tumori	Ara-C + cisplatin + vindesine in 32 advanced NSCLC patients; 18% response rate (5/28 evaluable); cross-tumour evidence for Ara-C + platinum activity in lung malignancies
2156598	1990	Phase II	Cancer	High-dose Ara-C (3 g/m²) + cisplatin (100 mg/m²) in 37 chemotherapy-naive NSCLC patients; 14% overall response; Grade IV myelosuppression in 32%, 4 treatment-related deaths — significant toxicity signal
2820740	1987	Pilot Study	Eur J Cancer Clin Oncol	Cisplatin + Cytarabine combination in advanced NSCLC pilot study; early safety and feasibility assessment for the Ara-C + platinum backbone
348088	1978	Review	Antibiotics Chemother	Ara-C analogues: mechanism of rapid inactivation by cytidine deaminase, rationale for cytidine deaminase inhibitors and longer-acting Ara-C derivatives — mechanistic context for resistance and formulation development

Singapore Market Information

Cytarabine is not currently registered in Singapore. No product authorisation records are on file, and there is no approved indication text available from local regulatory sources.

Cytotoxicity

Cytarabine is a conventional cytotoxic antimetabolite. Its indication in acute leukemia and lymphoma conditioning regimens clearly classifies it as an antineoplastic agent subject to cytotoxic handling requirements.

Item	Content
Cytotoxicity Classification	Conventional cytotoxic — Pyrimidine antimetabolite (S-phase specific)
Myelosuppression Risk	High — Neutropenia and thrombocytopenia are dose-limiting; Grade IV myelosuppression reported in approximately 32% of patients receiving high-dose regimens (3 g/m²); standard-dose regimens carry moderate-to-high bone marrow suppression risk
Emetogenicity Classification	Low to moderate at standard doses; moderate to high at high doses (≥1 g/m²)
Monitoring Items	CBC with differential count (before each cycle and at nadir, typically days 7–14); liver function tests; renal function (creatinine, BUN); neurological assessment for cerebellar toxicity (especially high-dose and intrathecal administration); ophthalmological review with high-dose therapy
Handling Protection	Must be prepared in a certified biological safety cabinet; full personal protective equipment (gloves, gown, eye protection) required; cytotoxic waste disposal per institutional and regulatory guidelines

Safety Considerations

No Singapore-specific package insert data, TFDA prescribing information, or drug interaction data is currently available for this evaluation. Please refer to the reference country SmPC or manufacturer's package insert for complete warnings, contraindications, and drug interaction information before any clinical use.

Conclusion and Next Steps

Decision: Hold

Rationale: Although the mechanistic rationale for Ara-C in SCLC is biologically plausible — both share a high S-phase fraction — the available direct clinical evidence is historical (1970s–1990s), characterised by small sample sizes, no randomised controlled comparisons, and significant haematological toxicity. Modern SCLC first-line treatment (platinum/etoposide ± immunotherapy) and second-line options (topotecan, lurbinectedin) have rendered Ara-C–based regimens non-competitive as a standard approach. Cytarabine is also not registered in Singapore, presenting a regulatory barrier.

To proceed, the following is needed:

Niche indication definition: Identify a specific clinical scenario where Cytarabine offers differentiated value — most likely refractory/relapsed SCLC with leptomeningeal metastasis — and scope a hypothesis-driven protocol accordingly
Contemporary preclinical validation: Updated in vitro and patient-derived xenograft (PDX) data in modern SCLC models, including assessment of cytidine deaminase expression (a key resistance mechanism) in SCLC versus AML
Mechanism of action documentation: Obtain complete MOA and pharmacokinetic data from DrugBank or primary literature to strengthen the mechanistic rationale section for any regulatory or ethics submission
Safety review: Compile full warnings, contraindications, and drug interaction profile from reference country SmPC (e.g., EMA, FDA) before any clinical programme design
Singapore regulatory pathway assessment: Evaluate requirements for clinical trial import authorisation and potential registration pathway through HSA if evidence supports progression
Disclaimer

This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.