A Phase 2 Biomarker - Enriched Study of TH-302 in Subjects With Advanced Melanoma
Hypoxia is an independent marker of a poor prognosis for subjects with metastatic melanoma
(Simonetti 2012, Lartigau 1997). Hypoxic melanoma cells are more likely to exhibit a
stem-cell like phenotype with an associated increased propensity for invasion, angiogenesis,
and metastasis formation compared to normoxic cells. Moreover, this phenotype is also
associated with treatment resistance. TH-302, a hypoxia activated prodrug (HAP), was
designed to target the hypoxic nature of tumours while having a minimal effect on normoxic
tissue. TH-302 belongs to a class of alkylating agents that have significant experimental
and clinical activity (Brock 1989). Preclinical data support the hypothesis that TH-302
targets hypoxic regions of tumours and is also able to kill tumour cells in normoxic regions
as a result of cytotoxin diffusion, leading to significant effects on tumour growth (Meng
2011). TH-302 has been investigated in over 700 subjects with solid tumours or hematologic
malignancies, including subjects with metastatic melanoma. In this subset a disease control
rate of 63% (3 subjects with partial responses and 9 subjects with stable disease out of a
total of 19) was observed in an early phase clinical trial of TH-302 (Weber 2010).
Predictive biomarkers for response and toxicity have yet to be identified for subjects with
advanced melanoma treated with TH-302. Optimal patient selection may be critical to maximize
the clinical benefit. A predictive biomarker approach will be investigated to try to
identify subjects most likely to benefit from TH-302. Given the hypoxia-targeting mechanism
of TH- 302, it is believed that hypoxia biomarkers will be the most informative for
identifying subjects likely to benefit from TH- 302; however, additional biomarkers
including DNA repair biomarkers will also be investigated. In addition, this approach will
also have potential to synergise with future immunotherapeutic approaches as suppressive T
regulatory cells are thought to reside within hypoxic niches within the tumour
microenvironment that would be amenable to targeting by TH-302.
Interventional
Endpoint Classification: Safety/Efficacy Study, Intervention Model: Single Group Assignment, Masking: Open Label, Primary Purpose: Treatment
Overall survival
2 years
No
Tillman Pearce, MD
Study Director
Threshold Pharmaceuticals
United States: Food and Drug Administration
TH-CR-413
NCT01864538
May 2013
June 2015
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