Mustang Bio, Inc. Quarterly report pursuant to Section 13 or 15(d)

Quarterly report pursuant to Section 13 or 15(d)

License, Clinical Trial and Sponsored Research Agreements (City of Hope - Sponsored Research and Clinical Trial Agreements) (Narrative) (Details)

License, Clinical Trial and Sponsored Research Agreements (City of Hope - Sponsored Research and Clinical Trial Agreements) (Narrative) (Details)			1 Months Ended						3 Months Ended		9 Months Ended
	Jul. 01, 2020 USD ($)	Jul. 03, 2017 USD ($)	Nov. 30, 2020 USD ($)	Oct. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Feb. 28, 2017 USD ($)	Mar. 31, 2015 USD ($) installment	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development expense									$ 14,083,000	$ 7,987,000	$ 36,603,000	$ 27,131,000
Sponsored Research and Clinical Trial Agreements [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development expense									1,756,000	734,000	4,858,000	4,900,000
Sponsored Research and Clinical Trial Agreements [Member] \| City of Hope National Medical Center ("COH") [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestones payable								$ 2,000,000.0
Number of installments \| installment								4
Research and development expense									0	0	0	500,000
Sponsored Research and Clinical Trial Agreements [Member] \| CD123 (MB-102) [Member] \| City of Hope National Medical Center ("COH") [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront fees paid							$ 19,450
Contribution toward patient costs							200,000
Contribution per patient							$ 97,490
Agreement term							3 years
Research and development expense									24,000	48,000	250,000	344,000
Sponsored Research and Clinical Trial Agreements [Member] \| IL13Ra2 (MB-101) [Member] \| City of Hope National Medical Center ("COH") [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront fees paid				$ 29,000			$ 9,300
Milestones payable							200,000
Additional milestone payments							$ 100,000
Contribution per patient				100,000
Agreement term							3 years
Research and development expense									199,000	96,000	992,000	422,000
Annual maintenance fee payable				200,000
Sponsored Research and Clinical Trial Agreements [Member] \| IL13Ra2 (MB-101) [Member] \| City of Hope National Medical Center ("COH") [Member] \| Maximum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Contribution toward patient costs											200,000
Sponsored Research and Clinical Trial Agreements [Member] \| CS1 (MB-104) [Member] \| City of Hope National Medical Center ("COH") [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestones payable						$ 800,000
Research and development expense									138,000	65,000	510,000	835,000
Sponsored Research and Clinical Trial Agreements [Member] \| CS1 (MB-104) [Member] \| City of Hope National Medical Center ("COH") [Member] \| Maximum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestones payable						$ 2,400,000
Sponsored Research and Clinical Trial Agreements [Member] \| HER2 (MB 103) [Member] \| City of Hope National Medical Center ("COH") [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestones payable					$ 29,375
Research and development expense									319,000	0	473,000	0
Sponsored Research and Clinical Trial Agreements [Member] \| HER2 (MB 103) [Member] \| City of Hope National Medical Center ("COH") [Member] \| Maximum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestones payable					$ 3,000,000.0
Sponsored Research and Clinical Trial Agreements [Member] \| PSCA (MB-105) [Member] \| City of Hope National Medical Center ("COH") [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestones payable				33,000
Research and development expense									23,000	0	69,000	0
Sponsored Research and Clinical Trial Agreements [Member] \| PSCA (MB-105) [Member] \| City of Hope National Medical Center ("COH") [Member] \| Maximum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestones payable				$ 2,300,000
Sponsored Research and Clinical Trial Agreements [Member] \| CD20 (MB-106) [Member] \| Fred Hutchinson Cancer Research Center [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestones payable		$ 5,300,000
Additional milestone payments			$ 800,000
Research and development expense									492,000	418,000	1,490,000	1,134,000
Sponsored Research and Clinical Trial Agreements [Member] \| ST. Jude - XSCID [Member] \| St. Jude Children's Research Hospital [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront fees paid	$ 1,100,000
Research and development expense									$ 330,000	$ 107,000	$ 610,000	$ 1,665,000