PRT3789

Presented interim data from the ongoing Phase 1 dose escalation study of PRT3789, its first-in-class IV SMARCA2 degrader, demonstrating clinical proof of concept Initiated a Phase 1 trial for PRT7732, its first-in-class oral SMARCA2 degrader in patients with SMARCA4-mutated cancers Presented first preclinical data from its next generation degrader antibody conjugate (Precision ADC) platform Interim phase 1 clinical data with potentially best-in-class CDK9 inhibitor, PRT2527, in hematological malignancies to be presented at the American Society of Hematology Annual Meeting in December 2024 Current cash runway into 2026 with $153.6 million in cash, cash equivalents and marketable securities as of September 30, 2024 WILMINGTON, Del., Nov. 06, 2024 (GLOBE NEWSWIRE) -- Prelude Therapeutics Incorporated (Nasdaq: PRLD), a clinical-stage precision oncology company, today reported its financial results for the third quarter ended September 30, 2024 and provided an update on its clinical development pipeline and other corporate developments. “Our third quarter was marked by dedicated execution and the achievement of essential milestones for our lead clinical programs targeting SMARCA2,” stated Kris Vaddi, Ph.D., Chief Executive Officer of Prelude. “We have demonstrated the first-ever clinical proof of concept with our first-in-class, highly selective IV SMARCA2 degrader, PRT3789, in patients with aggressive SMARCA4 mutated cancers including non-small cell lung cancer (NSCLC) and esophageal cancers as monotherapy. We also demonstrated an encouraging early safety profile with no overlapping toxicities in our ongoing PRT3789 combination study with docetaxel. We are focused on completing monotherapy dose escalation and rapidly enrolling combination arms to support advancement of PRT3789 into next phase of development, initially in these two cancer types.” Dr. Vaddi continued, “Additional accomplishments for the quarter include the commencement of patient enrollment for our first-in-class, highly selective oral SMARCA2 degrader, PRT7732 in a biomarker selected phase 1 trial. With two highly differentiated SMARCA2 degraders in the clinic, we are well-positioned to build on our leadership in this novel and important therapeutic class and provide optionality for patients. We look forward to reporting our progress on both of these programs beginning early 2025.” Dr. Vaddi also added, “Other milestones for the quarter included presentation of first preclinical data from our Precision ADC program demonstrating the potential of SMARCA2/4 degrader as a potent and effective payload on multiple antibodies, as well as acceptance of interim clinical data in hematological malignancies of our potential best-in-class CDK9 inhibitor, PRT2527 at the American Society of Hematology Meeting in December.” Clinical Program Updates and Upcoming Milestones PRT3789 – A first-in-class, highly selective, intravenous SMARCA2 DegraderPRT3789 is designed to treat patients with a SMARCA4 mutation. Patients with SMARCA4-mutated cancer have a poor prognosis. This represents an area of high unmet medical need. PRT3789 is in Phase 1 clinical development in patients with biomarker selected SMARCA4-mutated cancers. Enrollment remains on track, and the Company expects to conclude monotherapy dose escalation by year-end 2024 and identify a dose for advancement to registrational trials. In addition, enrollment of patients into back-fill cohorts enriched for NSCLC and SMARCA4 loss-of-function mutations is ongoing, as is enrollment of the combination with docetaxel cohort. The Company also initiated a Phase 2 clinical trial evaluating PRT3789 in combination with KEYTRUDA® (pembrolizumab) in patients with SMARCA4-mutated cancers, per the previously announced collaboration with Merck (known as MSD outside of the US and Canada). KEYTRUDA® is a registered trademark of Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA. Interim Phase 1 data presented at medical congresses in Q3 2024The Company presented the first interim clinical data updates of the Phase 1 dose escalation study of PRT3789 in SMARCA4 mutated cancers at ESMO Congress 2024 and the 36th EORTC-NCI-AACR Symposium. The presentations can be found at Publications - Prelude Therapeutics. As reported by investigators, PRT3789 was generally safe and well-tolerated at doses tested to date. Of the 26 advanced NSCLC or esophageal patients with Class 1 (loss of function) mutations who were evaluable for efficacy, RECIST confirmed partial responses (PRs) were observed in 4 patients (2 esophageal, 2 NSCLC). Of the 9 patients with Class 1 mutations treated at doses of 283 mg or higher, two had RECIST confirmed partial responses and both were NSCLC patients. Tumor shrinkage was observed in patients with both Class 1 and Class 2 SMARCA4 mutations. Additional patients on-study demonstrated clinical benefit as measured by prolonged SD, including one advanced NSCLC patient who remains stable and on study having been treated for more than a year. Initial observations of safety from evaluable patients in the PRT3789 plus docetaxel combination dose escalation arm of the trial were also presented. To date, PRT3789 in combination with docetaxel demonstrated an acceptable safety profile, with no dose limiting toxicities or study drug serious adverse events reported. PRT7732 – A potent, highly selective and orally bioavailable SMARCA2 DegraderPRT7732 is a highly selective and orally bioavailable SMARCA2 degrader. The Company initiated and enrolled our first patients in a phase 1 multi-dose escalation trial of PRT7732 (NCT06560645) in biomarker selected SMARCA4 mutated cancers. Pfizer Ignite CollaborationPrelude has entered into a collaboration agreement with Pfizer Ignite enabling streamlined access to Ignite services in support of Prelude’s SMARCA2 degrader development programs. Per Pfizer, Ignite is a service offering providing partners access to Pfizer’s significant resources, scale and expertise in developing potentially breakthrough medicines. Under the terms of the collaboration agreement, Prelude retains full ownership and global license rights to all of its programs. Precision ADC with SMARCA2/4 dual degrader payloadPrelude is developing potent SMARCA2/4 dual degraders that robustly inhibit cancer cell growth and induce cell death across multiple cancer types. The Company presented the first preclinical data from its Precision ADC platform at the 36th EORTC-NCI-AACR Symposium in October. The data demonstrated potent activity of a SMARCA 2/4 degrader payload when conjugated to a range of commercially available antibodies, including PSMA, TROP2, C-MET, CEACAM5, and CD33. The SMARCA2/4 degrader payload conjugated to an anti-PSMA antibody demonstrated tumor regressions and significantly better in vivo efficacy compared to a traditional PSMA-targeted cytotoxic ADC in xenograft models of prostate cancer at well tolerated doses. The presentation can be found at Publications - Prelude Therapeutics. PRT2527 – A potent and highly selective CDK9 InhibitorPRT2527 is a potent and highly selective CDK9 inhibitor that has the potential to avoid off-target toxicities observed with other less selective CDK9 inhibitors. The Company is currently advancing PRT2527 as monotherapy in both lymphoid and myeloid hematological malignancies, and in combination with zanubrutinib in B-cell malignancies. PRT2527 is expected to complete monotherapy dose escalation in B-cell malignancies this year. Initiation of dose escalation in myeloid malignancies occurred in the first half of 2024. Interim phase 1 clinical data with potentially best-in-class CDK9 inhibitor, PRT2527 in hematological malignancies will be presented at the American Society of Hematology Annual Meeting in December 2024. Third Quarter 2024 Financial Results  Cash, Cash Equivalents, and Marketable securities: Cash, cash equivalents and marketable securities as of September 30, 2024 were $153.6 million. The Company anticipates that its existing cash, cash equivalents and marketable securities will fund Prelude’s operations into 2026.  Research and Development (R&D) Expenses: For the third quarter of 2024, R&D expense increased to $29.5 million from $26.3 million for the prior year period. Included in the R&D expense for the three months ended September 30, 2024 was $3.4 million of non-cash expense related to stock-based compensation expense, including employee stock options, compared to $3.3 million for three months ended September 30, 2023. Research and development expenses increased primarily due to an increase in our chemistry, manufacturing, and controls (CMC) costs supporting our pre-clinical and clinical programs. We expect our R&D expenses to vary from quarter to quarter, primarily due to the timing of our clinical development activities. General and Administrative (G&A) Expenses: For the third quarter of 2024, G&A expenses increased to $7.9 million from $7.1 million for the prior year period. Included in general and administrative expenses for the three months ended September 30, 2024, was $2.5 million of non-cash expense related to stock-based compensation expense, including employee stock options, compared to $3.4 million for three months ended September 30, 2023. General and administrative expenses increased primarily due to an increase in professional fees incurred to support our research and development efforts. Net Loss: For the three months ended September 30, 2024, net loss was $32.3 million, or $0.43 per share compared to $30.6 million, or $0.45 per share, for the prior year period. Included in the net loss for the quarter ended September 30, 2024, was $5.9 million of non-cash expenses related to the impact of expensing share-based payments, including employee stock options, as compared to $6.7 million for the same period in 2023. About Prelude Therapeutics Prelude Therapeutics is a leading precision oncology company developing innovative medicines in areas of high unmet need for cancer patients. Our pipeline is comprised of several novel drug candidates including first-in-class, highly selective IV and oral SMARCA2 degraders, and a potentially best-in-class CDK9 inhibitor. We are also leveraging our expertise in targeted protein degradation to discover, develop and commercialize next generation degrader antibody conjugates (Precision ADCs) with partners. We are on a mission to extend the promise of precision medicine to every cancer patient in need. Our corporate presentation can be found at Events & Presentations - Prelude Therapeutics. For more information, visit preludetx.com. Cautionary Note Regarding Forward-Looking Statements This press release contains forward-looking statements within the meaning of the "safe harbor" provisions of the Private Securities Litigation Reform Act of 1995, including, but not limited to, anticipated discovery, preclinical and clinical development activities for Prelude’s product candidates, the potential safety, efficacy, benefits and addressable market for Prelude’s product candidates, the expected timeline for initial proof-of-concept data and clinical trial results for Prelude’s product candidates, and the sufficiency of Prelude’s cash runway into 2026. All statements other than statements of historical fact are statements that could be deemed forward-looking statements. The words “believes,” “anticipates,” “estimates,” “plans,” “expects,” “intends,” “may,” “could,” “should,” “potential,” “likely,” “projects,” “continue,” “will,” “schedule,” and “would” and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. These forward-looking statements are predictions based on the Company’s current expectations and projections about future events and various assumptions. Although Prelude believes that the expectations reflected in such forward-looking statements are reasonable, Prelude cannot guarantee future events, results, actions, levels of activity, performance or achievements, and the timing and results of biotechnology development and potential regulatory approval is inherently uncertain. Forward-looking statements are subject to risks and uncertainties that may cause Prelude's actual activities or results to differ significantly from those expressed in any forward-looking statement, including risks and uncertainties related to Prelude's ability to advance its product candidates, the receipt and timing of potential regulatory designations, approvals and commercialization of product candidates, clinical trial sites and our ability to enroll eligible patients, supply chain and manufacturing facilities, Prelude’s ability to maintain and recognize the benefits of certain designations received by product candidates, the timing and results of preclinical and clinical trials, Prelude's ability to fund development activities and achieve development goals, Prelude's ability to protect intellectual property, and other risks and uncertainties described under the heading "Risk Factors" in Prelude’s Annual Report on Form 10-K for the year ended December 31, 2023, its Quarterly Reports on Form 10-Q and other documents that Prelude files from time to time with the Securities and Exchange Commission. These forward-looking statements speak only as of the date of this press release, and Prelude undertakes no obligation to revise or update any forward-looking statements to reflect events or circumstances after the date hereof, except as may be required by law.  PRELUDE THERAPEUTICS INCORPORATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS(UNAUDITED) Three Months Ended September 30, (in thousands, except share and per share data) 2024 2023 Revenue from license agreement $3,000 $— Operating expenses Research and development 29,457 26,261 General and administrative 7,919 7,124 Total operating expenses 37,376 33,385 Loss from operations (34,376) (33,385) Other income, net 2,105 2,777 Net loss $(32,271) $(30,608) Per share information: Net loss per share of common stock, basic and diluted $(0.43) $(0.45) Weighted average common shares outstanding, basic and diluted 75,855,949 67,639,993 Comprehensive loss: Net loss $(32,271) $(30,608) Unrealized gain (loss) on marketable securities, net of tax 457 106 Comprehensive loss $(31,814) $(30,502) PRELUDE THERAPEUTICS INCORPORATED BALANCE SHEETS (in thousands, except share data) September 30,2024 December 31,2023 Assets (unaudited) Current assets: Cash and cash equivalents $11,134 $25,291 Marketable securities 142,492 207,644 Prepaid expenses and other current assets 2,761 2,654 Total current assets 156,387 235,589 Restricted cash 4,044 4,044 Property and equipment, net 7,202 7,325 Operating lease right-of-use asset 29,182 30,412 Other assets 405 295 Total assets $197,220 $277,665 Liabilities and stockholders’ equity Current liabilities: Accounts payable $5,921 $4,580 Accrued expenses and other current liabilities 13,579 15,768 Operating lease liability 2,365 1,481 Finance lease liability 359 — Total current liabilities 22,224 21,829 Other liabilities 3,153 3,339 Operating lease liability 15,412 15,407 Total liabilities 40,789 40,575 Commitments Stockholders’ equity: Voting common stock, $0.0001 par value: 487,149,741 shares authorized; 42,178,012 and 42,063,995 shares issued and outstanding at September 30, 2024 and December 31, 2023, respectively 4 4 Non-voting common stock, $0.0001 par value: 12,850,259 shares authorized; 12,850,259 shares issued and outstanding at both September 30, 2024 and December 31, 2023 1 1 Additional paid-in capital 711,091 693,252 Accumulated other comprehensive income 167 223 Accumulated deficit (554,832) (456,390) Total stockholders’ equity 156,431 237,090 Total liabilities and stockholders’ equity $197,220 $277,665 Investor Contact: Robert A. Doody, Jr.Senior Vice President, Investor RelationsPrelude Therapeutics Incorporated 484.639.7235rdoody@preludetx.com

– Interim data from ongoing trial of PRT3789 showed additional clinical activity at higher doses in patients with non-small cell lung cancer (NSCLC) – First safety data presented from combination study of PRT3789 and docetaxel demonstrated an acceptable safety profile – First preclinical proof-of-concept data presented from precision antibody drug conjugate program deploying a novel SMARCA2/4 dual degrader payload WILMINGTON, Del., Oct. 24, 2024 (GLOBE NEWSWIRE) -- Prelude Therapeutics Incorporated (Nasdaq: PRLD) (“Prelude” or the “Company”), a clinical-stage precision oncology company, today announced the presentation of additional data from its ongoing Phase 1 open-label, dose-escalation trial of PRT3789, a first-in-class, highly selective SMARCA2 degrader designed to treat cancer patients with a SMARCA4 mutation. The data were presented at a plenary session of the 36th Annual EORTC-NCI-AACR Symposium in Barcelona, Spain. The study investigators reported, as of September 23, 2024 (the Cutoff Date), additional follow up data on 65 patients that were enrolled, treated, and safety evaluable. PRT3789 was generally well-tolerated through 8 dosing cohorts. The majority of adverse events reported by investigators have been mild to moderate. Overall, of the 26 advanced, heavily pre-treated NSCLC or esophageal patients with Class 1 (loss of function) mutations evaluable for efficacy, now with additional follow up, RECIST partial responses (PRs) were confirmed in 4 patients, including 2 of 9 NSCLC patients with confirmed PRs at doses of 283 mg or higher. As anticipated, higher doses are resulting in deeper and more sustained SMARCA2 degradation in PBMCs. Additional patients demonstrated clinical benefit as measured by prolonged stable disease (SD) including one patient on treatment for more than a year. “We, along with our study investigators, are encouraged by the promising activity shown to date by PRT3789 in this novel first-in-class mechanism for patients who have limited treatment options,” stated Jane Huang, M.D., President and Chief Medical Officer of Prelude. “We look forward to further characterizing and understanding the full potential of PRT3789 through ongoing monotherapy dose escalation and in combination studies with both docetaxel and pembrolizumab.” PRT3789 Interim Phase 1 ResultsPRT3789 is currently being evaluated in an ongoing dose-escalation Phase 1 trial in heavily pre-treated patients with advanced solid tumors harboring any SMARCA4 mutation who have relapsed/refractory disease. Sixty-five patients with advanced cancer were treated once weekly via intravenous infusion at eight dose levels (24 mg, 48 mg, 80 mg, 120 mg, 160 mg, 212 mg, 283 mg, 376 mg), and follow up data reported through to September 23, 2024. The median age of these patients was 62 and the median number of prior treatments was 3 (ranging from 1-10). 34 patients (52.3%) presented with a Class 1 (loss of function) SMARCA4 mutation, while 24 patients (36.9%) presented with a Class 2 (missense, VUS) SMARCA4 mutation and 7 (10.8%) had a loss of SMARCA4 protein. Initial Safety DataPRT3789 was generally well-tolerated. Treatment emergent adverse events of any grade observed to date consisted of nausea (26.2%), fatigue (21.5%), anemia (20.0%), decreased appetite (20.0%), abdominal pain (18.5%), and constipation (18.5%). No dose limiting toxicities were observed and no study drug-related serious adverse events were reported. Pharmacokinetic (PK) and Pharmacodynamic (PD) DataPreliminary PK data was available from 24 mg to 376 mg dose cohorts. A general trend of increases in exposure (Cmax, AUC) with dose was observed. Mean concentrations were observed above SMARCA2 plasma DC50 (21 nM) for approximately 8 hours at the 376 mg dose. No accumulation was observed with repeat dose administration, consistent with the half-life and once-weekly administration. PD effect (as measured by SMARCA2 protein levels in peripheral blood mononuclear cells) observed was more prolonged than PK half-life. Higher dose levels, above 212 mg, demonstrated a deeper, more consistent, and more prolonged PD effect. SMARCA2 degradation was observed in both peripheral blood mononuclear cells (PBMC) and in available tumor tissue as shown through biopsy. Analysis of Initial Clinical ActivityOf the 26 advanced NSCLC or esophageal patients with Class 1 (loss of function) mutations who were evaluable for efficacy, RECIST confirmed partial responses (PRs) were observed in 4 patients (2 esophageal, 2 NSCLC), including 2 of 9 NSCLC patients with confirmed PRs at doses of 283 mg or higher. Tumor shrinkage was observed in patients with both Class 1 and Class 2 SMARCA4 mutations. Additional patients on-study demonstrated clinical benefit as measured by prolonged SD, including one advanced NSCLC patient who remains stable and on study having been treated for more than 1 year. Initial observations of safety from evaluable patients in the PRT3789 plus docetaxel combination dose escalation arm of the trial were also presented. To date, PRT3789 in combination with docetaxel demonstrated an acceptable safety profile, with no dose limiting toxicities or study drug serious adverse events reported. Additional SMARCA Degrader Presentations The Company also provided two poster presentations at the conference. The Selective SMARCA2 Degrader, PRT3789, Counteracts the Protective Cellular Stress Response to Chemotherapy and Enhances the Efficacy of Standard of Care Chemotherapeutic Agents in SMARCA4 Mutant NSCLC Models The combination of PRT3789 with standard of care NSCLC chemotherapy agents significantly enhances anti-tumor activity in preclinical models of SMARCA4-mutated NSCLC. Downregulation of dominant gene pathways by PRT3789, specifically counters docetaxel-induced upregulation of the E2F and G2/M pathways, resulting in a more comprehensive cell cycle blockade and increased apoptosis in SMARCA4-mutated cells. This synergistic activity was observed with both Class I (loss of function) mutations and Class II (missense) mutations. Discovery of First-in-Class Precision Antibody Drug Conjugates with a Potent SMARCA 2/4 Dual Degrader Payloads that Safely Achieve Maximal and Tumor Specific Degradation and Efficacy in Mouse Models PRP0004 is a potent SMARCA2/4 dual degrader that robustly inhibits cancer cell growth and induces cell death. Conjugation of PRP0004 to clinically-validated antibodies yielded novel degrader antibody conjugates (DACs), which demonstrated potent and antigen-selective internalization and SMARCA2 and SMARCA4 degradation in cell lines derived from multiple cancers. Prostate cancer cell lines were among the most sensitive to the PRP0004 degrader payload. PRP0004 downregulated multiple drivers of prostate cancer cell growth and survival and resulted in cell death, rationalizing the use of PSMA-targeting antibodies for initial proof-of-concept studies in preclinical models. As expected, dosing with PRP0004 on its own was highly efficacious in prostate cancer xenografts but displayed a narrow therapeutic window. However, when delivered as a payload on anti-PSMA antibodies, the anti-PSMA SMARCA2/4 DACs demonstrate robust SMARCA2 and SMARCA4 degradation and antigen-dependent efficacy in xenograft models while being well-tolerated. These data highlight the potential of this first-in-class precision ADC approach utilizing a highly potent SMARCA2/4 dual degrader payload to achieve maximal target degradation in tumors while sparing healthy tissues. This strategy has the potential to significantly expand the reach of Prelude’s novel SMARCA degraders to treating patients without SMARCA4 mutations. “Preclinical data presented today with our novel approach to develop degrader antibody conjugates by using potent dual degraders of SMARCA2 and 4 as payloads offers first proof-of-concept of effectively and safely targeting an important mechanism to treat cancers beyond those with SMARCA4 mutations” stated Peggy Scherle, Ph.D., Chief Scientific Officer of Prelude. All of the above noted presentations can be found at Publications - Prelude Therapeutics (preludetx.com). About PRT3789-01PRT3789 is a first-in-class, potent and highly selective SMARCA2 degrader, in Phase 1 clinical development in SMARCA4-mutated patients. Enrollment remains on track, and the Company expects to conclude monotherapy dose escalation by year end 2024 and identify the biologically active dose to advance for future registrational trials. In addition, enrollment of patients into back-fill cohorts enriched for NSCLC and SMARCA4 loss-of-function mutations at higher dose levels is ongoing. The objective is to assess clinical activity in a more homogeneous group of patients with high unmet need to support planned discussions with regulatory agencies. A maximum tolerated dose has not yet been identified. Dose escalation continues, now in the 10th dosing cohort (665 mg IV once weekly). About Prelude Therapeutics Prelude Therapeutics is a leading precision oncology company developing innovative medicines in areas of high unmet need for cancer patients. Our pipeline is comprised of several novel drug candidates including first-in-class, highly selective IV and oral SMARCA2 degraders, and a potentially best-in-class CDK9 inhibitor. We are also leveraging our expertise in targeted protein degradation to discover, develop and commercialize next generation degrader antibody conjugates (Precision ADCs) with partners. We are on a mission to extend the promise of precision medicine to every cancer patient in need. For more information, visit preludetx.com. Cautionary Note Regarding Forward-Looking Statements This press release contains forward-looking statements within the meaning of the "safe harbor" provisions of the Private Securities Litigation Reform Act of 1995, including, but not limited to, anticipated discovery, preclinical and clinical development activities for Prelude’s product candidates, the potential safety, efficacy, benefits and addressable market for Prelude’s product candidates, and clinical trial results for Prelude’s product candidates. All statements other than statements of historical fact are statements that could be deemed forward-looking statements. The words “believes,” “anticipates,” “estimates,” “plans,” “expects,” “intends,” “may,” “could,” “should,” “potential,” “likely,” “projects,” “continue,” “will,” “schedule,” and “would” and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. These forward-looking statements are predictions based on the Company’s current expectations and projections about future events and various assumptions. Although Prelude believes that the expectations reflected in such forward-looking statements are reasonable, Prelude cannot guarantee future events, results, actions, levels of activity, performance or achievements, and the timing and results of biotechnology development and potential regulatory approval is inherently uncertain. Forward-looking statements are subject to risks and uncertainties that may cause Prelude's actual activities or results to differ significantly from those expressed in any forward-looking statement, including risks and uncertainties related to Prelude's ability to advance its product candidates, the receipt and timing of potential regulatory designations, approvals and commercialization of product candidates, clinical trial sites and our ability to enroll eligible patients, supply chain and manufacturing facilities, Prelude’s ability to maintain and recognize the benefits of certain designations received by product candidates, the timing and results of preclinical and clinical trials, Prelude's ability to fund development activities and achieve development goals, Prelude's ability to protect intellectual property, and other risks and uncertainties described under the heading "Risk Factors" in Prelude’s Annual Report on Form 10-K for the year ended December 31, 2023, its Quarterly Reports on Form 10-Q and other documents that Prelude files from time to time with the Securities and Exchange Commission. These forward-looking statements speak only as of the date of this press release, and Prelude undertakes no obligation to revise or update any forward-looking statements to reflect events or circumstances after the date hereof, except as may be required by law.  Investor Contact: Robert A. Doody Jr.Senior Vice President, Investor Relations 484.639.7235rdoody@preludetx.com