Condensed Consolidated Balance Sheets (USD $)	Mar. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 4,739,472	$ 1,477,143
Grants receivable	239,539us-gaap_GrantsReceivableCurrent	84,344us-gaap_GrantsReceivableCurrent
Prepaid expenses	302,155us-gaap_PrepaidExpenseCurrent	334,629us-gaap_PrepaidExpenseCurrent
Other current assets	400us-gaap_OtherAssetsCurrent	14,675us-gaap_OtherAssetsCurrent
Total current assets	5,281,566us-gaap_AssetsCurrent	1,910,791us-gaap_AssetsCurrent
Property and equipment, net	81,597us-gaap_PropertyPlantAndEquipmentNet	57,053us-gaap_PropertyPlantAndEquipmentNet
Goodwill	6,826,003us-gaap_Goodwill	6,826,003us-gaap_Goodwill
Other long term assets	11,017us-gaap_OtherAssetsNoncurrent	11,017us-gaap_OtherAssetsNoncurrent
Total assets	12,200,183us-gaap_Assets	8,804,864us-gaap_Assets
Current liabilities:
Accounts payable	2,066,431us-gaap_AccountsPayableCurrent	1,313,247us-gaap_AccountsPayableCurrent
Accrued compensation	318,815	230,381
Accrued clinical operations and site costs	516,957us-gaap_AccruedLiabilitiesCurrent	494,110us-gaap_AccruedLiabilitiesCurrent
Accrued lease contingency fee	590,504	590,504
Other accrued expenses	445,904us-gaap_OtherAccruedLiabilitiesCurrent	245,421us-gaap_OtherAccruedLiabilitiesCurrent
Warrant liability		92,463mbvx_FairValueOfWarrantLiability
Total current liabilities	3,938,611us-gaap_LiabilitiesCurrent	2,966,126us-gaap_LiabilitiesCurrent
Redeemable convertible preferred stock:
Redeemable convertible preferred stock, value		1,838,025
Stockholders' equity:
Common stock	125,255us-gaap_CommonStockValue	28,029us-gaap_CommonStockValue
Additional paid-in capital	53,077,718	24,492,450
Accumulated deficit	(44,943,783)	(24,550,308)
Total stockholders' equity	8,261,572us-gaap_StockholdersEquity	4,000,713us-gaap_StockholdersEquity
Total liabilities, redeemable convertible preferred stock and stockholders' equity	12,200,183	8,804,864
Redeemable Convertible Preferred Stock [Member]
Redeemable convertible preferred stock:
Redeemable convertible preferred stock, value
Series A-1 Convertible Preferred Stock [Member]
Stockholders' equity:
Convertible preferred stock		4,029,576
Series C Convertible Preferred Stock [Member]
Stockholders' equity:
Convertible preferred stock		966
Series D Convertible Preferred Stock [Member]
Stockholders' equity:
Convertible preferred stock	$ 2,382

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