XML 44 R37.htm IDEA: XBRL DOCUMENT
v3.25.2

Fair Value Measurements - Summary of Key Level 3 Inputs Used in Valuation of Warrants Liability at Fair Value (Details) | Jun. 17, 2025 | Mar. 04, 2025 | Feb. 13, 2025
--- | --- | --- | ---
March 2025 Series A and Series B Warrants | Interest Rate [Member] |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |
Warrant liability, Measurement input | 3.91 |  | 3.98
March 2025 Series A and Series B Warrants | Remaining Term [Member] |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |
Warrant liability, Remaining term (years) | 4 years 10 months 24 days |  | 6 years 1 month 6 days
March 2025 Series A and Series B Warrants | Volatility [Member] |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |
Warrant liability, Measurement input | 135.6 |  | 123.7
March 2025 Series B Warrants [Member] | Interest Rate [Member] | Minimum [Member] |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |
Warrant liability, Measurement input |  | 3.85 |
March 2025 Series B Warrants [Member] | Interest Rate [Member] | Maximum [Member] |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |
Warrant liability, Measurement input |  | 4.06 |
March 2025 Series B Warrants [Member] | Remaining Term [Member] | Minimum [Member] |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |
Warrant liability, Remaining term (years) |  | 4 years 10 months 24 days |
March 2025 Series B Warrants [Member] | Remaining Term [Member] | Maximum [Member] |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |
Warrant liability, Remaining term (years) |  | 5 years |
March 2025 Series B Warrants [Member] | Volatility [Member] | Minimum [Member] |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |
Warrant liability, Measurement input |  | 133.9 |
March 2025 Series B Warrants [Member] | Volatility [Member] | Maximum [Member] |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |
Warrant liability, Measurement input |  | 135.8 |
February 2025 Warrants [Member] | Interest Rate [Member] |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |
Warrant liability, Measurement input |  | 4.3 | 4.3
February 2025 Warrants [Member] | Remaining Term [Member] |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |
Warrant liability, Remaining term (years) |  | 4 years 11 months 12 days | 5 years
February 2025 Warrants [Member] | Volatility [Member] |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |
Warrant liability, Measurement input |  | 102.1 | 98.5
February 2025 Warrants [Member] | Fair Value of Common Stock [Member] |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |
Warrant liability, Measurement input |  | 0.3 | 1.2

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 805 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479328/805-10-50-8 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 805 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 43 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479303/805-10-55-43 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 4: http://www.xbrl.org/2003/role/exampleRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 103 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482078/820-10-55-103 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(2)(i) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 + Details
Name: | us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Value of input used to measure outstanding warrant and right embodying unconditional obligation requiring redemption by transferring asset at specified or determinable date or upon event certain to occur. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(2)(i) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 + Details
Name: | us-gaap_WarrantsAndRightsOutstandingMeasurementInput
Namespace Prefix: | us-gaap_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition Period between issuance and expiration of outstanding warrant and right embodying unconditional obligation requiring redemption by transferring asset at specified or determinable date or upon event certain to occur, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(2)(i) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 + Details
Name: | us-gaap_WarrantsAndRightsOutstandingTerm
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_FairValueByLiabilityClassAxis=pstv_MarchTwoThousandTwentyFiveSeriesAWarrantsAndSeriesBWarrantsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=pstv_MeasurementInputInterestRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=pstv_MeasurementInputRemainingTermMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=us-gaap_MeasurementInputPriceVolatilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByLiabilityClassAxis=pstv_MarchTwoThousandTwentyFiveSeriesBWarrantsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByLiabilityClassAxis=pstv_FebruaryTwoThousandTwentyFiveWarrantsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MeasurementInputTypeAxis=pstv_MeasurementInputFairValueOfCommonStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |