What changed in PLUS THERAPEUTICS, INC.'s 10-K — 2023 vs 2024

Item 1. Financ ial Statements Report of Indepen dent Registered Public Accounting Firm Shareholders and Board of Directors Plus Therapeutics, Inc. Austin, Texas Opinion on the Financial Statements We have audited the accompanying balance sheets of Plus Therapeutics, Inc.

(the “Company”) as of December 31, 2023 and 2022, the related statements of operations, stockholders’ equity (deficit), and cash flows for each of the years then ended and the related notes (collectively referred to as the “financial statements”).

In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company at December 31, 2023 and 2022, and the results of its operations and its cash flows for each of the years then ended, in conformity with accounting principles generally accepted in the United States of America.

Going Concern Uncertainty The accompanying financial statements have been prepared assuming that the Company will continue as a going concern. As discussed in Note 1 to the financial statements, the Company has suffered recurring losses and negative cash flows from operations that raise substantial doubt about its ability to continue as a going concern.

Management’s plans in regard to these matters are also described in Note 1. The financial statements do not include any adjustments that might result from the outcome of this uncertainty. Basis for Opinion These financial statements are the responsibility of the Company’s management. Our responsibility is to express an opinion on the Company’s financial statements based on our audits.

We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (“PCAOB”) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud.

The Company is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. As part of our audits we are required to obtain an understanding of internal control over financial reporting but not for the purpose of expressing an opinion on the effectiveness of the Company’s internal control over financial reporting.

Accordingly, we express no such opinion. Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements.

Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.

Critical Audit Matter The critical audit matter communicated below is a matter arising from the current period audit of the financial statements that was communicated or required to be communicated to the audit committee and that: (1) relates to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective, or complex judgments.

The communication of the critical audit matter does not alter in any way our opinion on the financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing separate opinions on the critical audit matter or on the accounts or disclosures to which it relates.

Determination of Research and Development Cost Associated With Recording of Grant Revenue 65 As described in Note 9 to the financial statements, in September 2022, the Company entered into a contract with the Cancer Prevention and Research Institute of Texas (“CPRIT”) pursuant to which CPRIT will provide the Company a grant of up to $17.6 million (the “CPRIT Grant”) over a three-year period.

The CPRIT Grant is subject to customary CPRIT funding conditions, including, but not limited to, fund the continued development of rhenium ( 186 Re) obisbemeda for the treatment of patients with leptomeningeal metastases (“LM”).” The Company recognized $4.9 million in grant revenue from the CPRIT Grant during the year ended December 31, 2023.

We identified the determination of research and development costs incurred associated with the CPRIT Grant as a critical audit matter because of the subjectivity required to appropriately determine whether such costs satisfied the funding conditions. Auditing this element involved especially challenging and subjective auditor judgment due to the nature and extent of auditor effort required to address the matter.

The primary procedures we performed to address this critical audit matter included: • Reviewing the CPRIT Grant agreement to understand the conditions for which research and development costs satisfy the funding conditions. • Reviewing evidence of CPRIT’s approval of costs submitted by the Company that were applied to the CPRIT Grant funding conditions. • Inspecting a sample of vendor agreements and invoice detail to determine whether certain charges satisfy the CPRIT Grant funding conditions. /s/ BDO USA, P.C.

We have served as the Company’s auditor since 2016. Austin, Texas March 5, 2024 66 PLUS THERAPEUTICS, INC.

B ALANCE SHEETS (in thousands, except share and par value data) As of December 31, 2023 2022 Assets Current assets: Cash and cash equivalents $ 8,554 $ 18,120 Other current assets 1,280 3,697 Total current assets 9,834 21,817 Property and equipment, net 906 1,324 Operating lease right-use-of assets 202 248 Goodwill 372 372 Intangible assets, net 42 94 Other assets 32 12 Total assets $ 11,388 $ 23,867 Liabilities and Stockholders’ Equity (Deficit) Current liabilities: Accounts payable and accrued expenses $ 6,631 $ 10,134 Operating lease liability 120 110 Term loan obligation, current 3,976 1,608 Total current liabilities 10,727 11,852 Noncurrent operating lease liability 85 141 Term loan obligation — 3,786 Deferred grant liability 1,924 1,643 Total liabilities 12,736 17,422 Commitments and contingencies (Note 6) Stockholders’ equity (deficit): Preferred stock, $ 0.001 par value; 5,000,000 shares authorized; 1,952 shares issued and outstanding as of December 31, 2023 and 2022 — — Common stock, $ 0.001 par value; 100,000,000 shares authorized; 4,522,656 issued and 4,444,097 outstanding as of December 31, 2023, 2,240,092 shares issued and outstanding as of December 31, 2022, respectively 5 2 Treasury stock (at cost, 78,559 shares as of December 31, 2023) ( 126 ) — Additional paid-in capital 479,274 473,628 Accumulated deficit ( 480,501 ) ( 467,185 ) Total stockholders’ equity (deficit) ( 1,348 ) 6,445 Total liabilities and stockholders’ equity (deficit) $ 11,388 $ 23,867 See Accompanying Notes to these Financial Statements 67 PLUS THERAPEUTICS, INC.

STATEMENTS OF OPE RATIONS (in thousands, except share and per share data) For the Years Ended December 31, 2023 2022 Grant revenue $ 4,913 $ 224 Operating expenses: Research and development 9,690 9,698 General and administrative 8,544 10,238 Total operating expenses 18,234 19,936 Operating loss ( 13,321 ) ( 19,712 ) Other income (expense): Interest income 400 147 Interest expense ( 395 ) ( 711 ) Change in fair value of liability instruments — 1 Total other income (expense) 5 ( 563 ) Net loss $ ( 13,316 ) $ ( 20,275 ) Net loss per share, basic and diluted $ ( 4.24 ) $ ( 11.58 ) Basic and diluted weighted average shares used in calculating net loss per share attributable to common stockholders 3,140,925 1,750,350 See Accompanying Notes to these Financial Statements 68 PLUS THERAPEUTICS, INC.

STATEMENTS OF ST OCKHOLDERS’ EQUITY (DEFICIT) (in thousands, except share data) Convertible Additional Total Preferred Stock preferred stock Common stock paid-in Accumulated stockholders’ Shares Amount Shares Amount Shares Amount Treasury Stock capital deficit equity (deficit) Balance at December 31, 2021 — — 1,952 — 1,034,002 1 — — 457,745 ( 446,910 ) 10,836 Share-based compensation — — — — — — — — 606 — 606 Sale of common stock, net — — — — 1,206,090 1 — — 15,277 — 15,278 Net loss — — — — — — — — — ( 20,275 ) ( 20,275 ) Balance at December 31, 2022 — $ — 1,952 $ — 2,240,092 $ 2 — $ — $ 473,628 $ ( 467,185 ) $ 6,445 Issuance of Series F preferred stock 1 — — — — — — — — — — Redemption of Series F preferred stock ( 1 ) — — — — — — — — — — Share-based compensation — — — — — — — — 569 — 569 Sale of common stock, net — — — — 2,230,493 3 — — 5,002 — 5,005 Issuance of common stock for in process research and development — — — — 53,381 — — — 75 — 75 Fractional adjustment — — — — ( 1,310 ) — — — — — — Purchase of treasury stock — — — — — — ( 78,559 ) ( 126 ) — — ( 126 ) Net loss — — — — — — — — — ( 13,316 ) ( 13,316 ) Balance at December 31, 2023 — $ — 1,952 $ — 4,522,656 $ 5 ( 78,559 ) $ ( 126 ) $ 479,274 $ ( 480,501 ) $ ( 1,348 ) See Accompanying Notes to these Financial Statements 69 PLUS THERAPEUTICS, INC.

STATEM ENTS OF CASH FLOWS (in thousands) For the Years Ended December 31, 2023 2022 Cash flows used in operating activities: Net loss $ ( 13,316 ) $ ( 20,275 ) Adjustments to reconcile net loss to net cash used in operating activities: Depreciation and amortization 628 619 Amortization of deferred financing costs and debt discount 190 389 Common stock issued for research and development 75 — Change in fair value of liability instruments — ( 1 ) Loss on disposal of property and equipment 2 — Share-based compensation expense 569 606 Reduction in the carrying amount of operating lease right-of-use assets 117 93 Increases (decreases) in cash caused by changes in operating assets and liabilities: Other assets 2,397 ( 2,369 ) Accounts payable and accrued expenses ( 3,677 ) 6,452 Change in operating lease liabilities ( 117 ) ( 129 ) Deferred grant liability 281 1,643 Net cash used in operating activities ( 12,851 ) ( 12,972 ) Cash flows used in investing activities: Purchases of property and equipment and intangible assets ( 160 ) ( 509 ) In process research and development acquired — ( 250 ) Net cash used in investing activities ( 160 ) ( 759 ) Cash flows from financing activities: Principal payments of long-term obligations ( 1,608 ) ( 1,608 ) Gross proceeds from sale of common stock 5,527 15,832 Payment of offering costs related to sale of common stock ( 348 ) ( 773 ) Purchase of treasury stock ( 126 ) — Net cash provided by financing activities 3,445 13,451 Net decrease in cash and cash equivalents ( 9,566 ) ( 280 ) Cash and cash equivalents at beginning of period 18,120 18,400 Cash and cash equivalents at end of period $ 8,554 $ 18,120 Supplemental disclosure of cash flows information: Cash paid during period for: Interest $ 222 $ 327 Supplemental schedule of non-cash investing and financing activities: Unpaid offering cost $ 174 $ — Common stock issued in payment for in process research and development $ 75 $ — Right-of-use assets acquired by assuming operating lease liabilities $ 71 $ — See Accompanying Notes to these Financial Statements 70 PLUS THERAPEUTICS, INC.

NOTES TO FINANCIAL STATEMENTS December 31, 2023 1. Organization and Operations The Company Plus Therapeutics, Inc. is a clinical-stage pharmaceutical company focused on the development, manufacture and commercialization of complex and innovative treatments for patients battling cancer and other life-threatening diseases.

Certain Risks and Uncertainties The Company’s prospects are subject to the risks and uncertainties frequently encountered by companies in the early stages of development and commercialization, especially those companies in rapidly evolving and technologically advanced industries such as the biotech/medical device field.

The Company’s future viability largely depends on its ability to complete development of new products and receive regulatory approvals for those products. No assurance can be given that the Company’s new products will be successfully developed, regulatory approvals will be granted, or acceptance of these products will be achieved.

Going Concern The Company incurred net losses of $ 13.3 million for the year ended December 31, 2023, and as of December 31, 2023, the Company had an accumulated deficit of $ 480.5 million and cash and cash equivalents of $ 8.6 million.

Additionally, the Company used net cash of $ 12.9 million to fund its operating activities for the year ended December 31, 2023. The Company's term loan has an outstanding principal of $ 0.8 million principal and a $ 3.2 million final payment fee due June 1, 2024 (Note 8).

The Company expects that its research and development expenditures will increase in absolute dollars in 2024 and beyond. These factors raise substantial doubt about the Company’s ability to continue as a going concern. As disclosed in more detail in Note 12, the Company has entered into various financing agreements and raised capital by issuing its common stock.

Based on the Company’s stockholders’ deficit of $ 1.3 million as of December 31, 2023, the Company does not meet the minimum stockholders’ equity requirement for continued listing on the Nasdaq Capital Market under Nasdaq Listing Rule 5550(b)(1).

The Company expects to receive written notice from Nasdaq staff to that effect following the filing of the Annual Report on Form 10-K in which these financial statements are included. The Company continues to seek additional capital through strategic transactions and from other financing alternatives.

Without additional capital, current working capital and cash generated from sales will not provide adequate funding to make debt repayments, for research, sales and marketing efforts and product development activities at their current levels.

If sufficient capital is not raised, the Company will at a minimum need to significantly reduce or curtail its research and development and other operations, and this would negatively affect its ability to achieve corporate growth goals. Should the Company fail to raise additional cash from outside sources, this would have a material adverse impact on its operations.

The accompanying financial statements have been prepared assuming the Company will continue to operate as a going concern, which contemplates the realization of assets and settlement of liabilities in the normal course of business, and do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts and classifications of liabilities that may result from uncertainty related to its ability to continue as a going concern.

Amendments to Certificate of Incorporation and Reverse Stock Split At the Annual Meeting of Stockholders of the Company held on April 20, 2023 (the “Annual Meeting”), the stockholders of the Company approved an amendment to the Company’s Amended and Restated Certificate of Incorporation (the “Charter”) to implement a reverse stock split of the Company’s common stock, par value $ 0.001 per share, with the ratio to be determined by the Board of Directors (the “Board”) of the Company, within a range of not less than 1-for-3 and not greater than 1-for-15 .

Subsequently, on April 21, 2023, the Board determined to fix the ratio for the reverse stock split at 1-for-15 , without any change to its par value (the "Reverse Stock Split").

On April 27, 2023, following stockholder and Board approval, the Company filed a Certificate of Amendment to its Charter (the “Amendment”), with the Secretary of State of the State of Delaware to effectuate the Reverse Stock Split. The Amendment became effective on May 1, 2023 .

Upon effectiveness of the Reverse Stock Split, the number of shares of the Company’s common stock 71 (x) issued and outstanding decreased from approximately 37.4 million shares to approximately 2.5 million shares; (y) reserved for issuance upon exercise of outstanding warrants and options decreased from approximately 2.0 million shares to app roximately 0.1 million shares, and (z) reserved but unallocated under the Company’s current equity incentive plans decreased from approximately 3.0 million common shares to approximately 0.2 million common shares.

The Company's common stock began trading on the NASDAQ Capital Market on a post-split basis on May 1, 2023. The Company’s 5,000,000 shares of authorized Preferred Stock were not affected by the Reverse Stock Split.

No fractional shares were issued in connection with the Reverse Stock Split, and accordingly, the outstanding number of shares post Reverse Stock Split was adjusted down by approximately 1,310 (post-effect of Reverse Stock Split) shares.