Collaboration Agreements	12 Months Ended
Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaboration Agreements	4. Collaboration Agreements GSK On July 1, 2021, the Company entered into a Collaboration and License Agreement with Glaxo Wellcome UK Limited, a subsidiary of GlaxoSmithKline plc (GSK), pursuant to which the Company and GSK collaborate on the global development and commercialization of progranulin-elevating monoclonal antibodies, including latozinemab (also referred to as AL001), and AL101 (GSK Agreement). The GSK Agreement was made effective on August 17, 2021. Under the terms of the GSK Agreement, the Company received $700 million in upfront payments, of which $500 million was received in August 2021 and $200 million was received in January 2022. In addition, based on the development and commercialization plan for latozinemab and AL101, the Company may be eligible to receive up to an additional $1.5 billion in clinical development, regulatory, and commercial launch-related milestone payments. In the United States, the Company and GSK will equally share profits and losses from commercialization of latozinemab and AL101. Outside of the United States, the Company will be eligible for double-digit tiered royalties. The Company and GSK will jointly develop latozinemab and AL101, with GSK conducting Phase 3 clinical trials for Alzheimer’s disease and Parkinson’s disease and other non-orphan indications. The Company and GSK will share development costs 60% by GSK and 40% by the Company, except that the Company will solely bear the development costs of the initial Phase 2 clinical trials under the development plan, and the parties will share manufacturing development costs equally. The Company concluded that the GSK Agreement is within the scope of ASC 808, Collaborative Arrangements, as both parties are active participants in the activities and are exposed to significant risks and rewards dependent on the success of the commercialization of AL001 and AL101. Certain elements are required to be accounted for under ASC 606, Revenue From Contracts With Customers, where the counterparty is a customer for a good or service that is a distinct unit of account. The Company determined that the distinct performance obligations under ASC 606 consisted of: (i) license and know-how to AL001 FTD-GRN, which is currently in Phase 3 clinical development and (ii) the research and development activities, including license rights and know-how, relating to products in Phase 2 or earlier stages of development. The transaction price at inception and as of December 31, 2022, included fixed consideration consisting of the upfront payments of $700 million. All potential future milestones and other payments were considered constrained at the inception of the GSK Agreement and as of December 31, 2022, since the Company could not conclude it was probable that a significant reversal in the amount of revenue recognized would not occur. The respective standalone value for each of the performance obligations was allocated to the transaction price. The estimated SSP of each performance obligation was determined using discounted cash flows from the expected commercialization of AL001 and AL101 and estimated research and development costs to be incurred by the Company in the initial Phase 2 clinical trials. The estimate of SSP for each performance obligation reflects management's assumptions, which may include forecasted revenues, development timelines, discount rates, and probabilities of technical and regulatory success. For the license for FTD-GRN, the Company determined that GSK could benefit from the license at the time the license was granted and therefore, the related performance obligation was satisfied at a point in time. For the product candidates in Phase 2 or earlier stages of development, the Company determined that GSK could not benefit from the licenses without the corresponding development services that the Company has committed to perform due the earlier stage of development for these licenses. Except where agreed to otherwise, the Company will perform research and development activities through the end of the initial Phase 2 clinical trials. Revenue will be recognized over time as the research and development activities are performed. The Company will measure progress based on actual costs incurred to date compared to the overall total expected costs to satisfy the performance obligations. The research and development activities for products in Phase 3 clinical development were determined to be within the scope of ASC 808. Both parties will be active participants in the development, manufacturing, and commercialization of the product and are exposed to significant risks and rewards that are dependent on the commercial success of the products. The Company and GSK participate in profit and loss sharing for each program commensurate with each party's cost-sharing responsibilities during research and development. ASC 808 does not provide recognition and measurement guidance. As such, the Company determined that ASC 730, Research and Development, was appropriate to analogize to based on the nature of the cost-sharing provision of the agreement. The Company has concluded that payments to or reimbursements from GSK related to these services will be accounted for as an increase to or reduction of research and development expenses, respectively. Collaboration revenue under the GSK Agreement during the year ended December 31, 2022 and 2021, was $62.9 million and $192.1 million, respectively. The deferred revenue related to the GSK Agreement was $444.9 million and $307.9 million as of December 31, 2022 and 2021. The deferred revenue is expected to be recognized over the research and development period of the programs through the completion of initial Phase 2 clinical trials. Costs associated with co-development activities performed under the agreement are included in research and development expenses in the consolidated statements of operations, with any reimbursement of costs by GSK reflected as a reduction of such expenses. For the year ended December 31, 2022 and 2021, the Company recognized a reduction of research and development expense of $14.7 million and $8.8 million, respectively, under the GSK Agreement. AbbVie The Company entered into an agreement in October 2017 with AbbVie Biotechnology, Ltd. (AbbVie) to co-develop antibodies to two program targets in preclinical development (AbbVie Agreement). Under the terms of the AbbVie Agreement, AbbVie made $205.0 million in upfront payments, of which $5.0 million and $200.0 million were received by the Company in October 2017 and January 2018, respectively. The Company was to perform research and development services for the two programs through the end of Phase 2 clinical trials, which were each considered to be separate performance obligations. AbbVie decided to terminate one of the two collaboration programs, the CD33 collaboration program, after AbbVie and Alector collaboratively reviewed next steps for AL003, the asset being developed under that program, and concluded that further development of AL003 was not warranted. AbbVie provided written notice to terminate the CD33 collaboration program on June 30, 2022. The Company will no longer continue development of this program and will not be eligible for any future milestones related to that program from AbbVie. The Company continues to develop the AL002 program under the AbbVie Agreement. AbbVie has the exclusive right to exercise an option under the AbbVie Agreement with the Company for $250.0 million. If AbbVie exercises its option for the AL002 program, AbbVie would take over the development beginning with Phase 3 clinical trials, and the product candidates program costs will be split between the parties. The Company would also share in profits and losses upon commercialization of any products. However, following AbbVie’s exercise of its option for the AL002 program, the Company may opt out of sharing in development costs and profits or losses for that program and instead receive tiered royalties. In February 2023, the Company and AbbVie amended the AbbVie agreement, which will result in the Company receiving a $17.8 million milestone payment for the dosing of the first patient in a long-term extension study. Additionally, under the terms of the AbbVie Agreement, the Company will be eligible to earn up to an additional $225.0 million in milestone payments related to the regulatory approval for up to three indications. The Company assessed its collaboration agreement with AbbVie in the context of the delivery of the research and development services. The transaction price at inception and as of December 31, 2022, included fixed consideration consisting of the upfront payments of $205 million. All potential future milestones and other payments were considered constrained at the inception of the AbbVie Agreement and as of December 31, 2022, since the Company could not conclude it was probable that a significant reversal in the amount of revenue recognized would not occur. Collaboration revenue under the AbbVie Agreement during the years ended December 31, 2022, 2021, and 2020 was $70.7 million, $14.9 million, and $21.1 million, respectively. The deferred revenue related to the AbbVie Agreement was $46.7 million and $117.4 million as of December 31, 2022 and 2021, respectively. The deferred revenue is expected to be recognized over the research and development period of the programs through the AL002 program through the completion of Phase 2 clinical trials. For the year ended December 31, 2022, we recorded a net increase to collaboration revenue under the AbbVie Agreement due to changes in estimated costs to satisfy the performance obligations resulting from the termination of the AL003 program, partially offset by increases in total expected costs for the AL002 program. Innovent The Company entered into an agreement in March 2020 with Innovent Biologics (Innovent) to license, develop, and commercialize AL008 in China (Innovent Agreement). AL008 is the Company’s novel antibody targeting the CD47-SIRP-alpha pathway, a potent survival pathway co-opted by tumors to evade the innate immune system. Under the terms of the Innovent Agreement, Innovent would pay the Company up to $11.5 million in development milestones, $112.5 million in sales milestones, and future royalties on sales and the Company would retain the rights to develop and commercialize AL008 outside of China. The Company determined there is one performance obligation for the delivery of the license and will recognize revenue when it is probable that there will not be significant reversal of cumulative revenue. Development and sales milestones under the Innovent Agreement were not included in the transaction price, as all these amounts were fully constrained as of December 31, 2022. As of December 31, 2022, no revenue has been recognized and no payments have been received under the Innovent Agreement.

Collaboration Agreements

12 Months Ended

Dec. 31, 2022

Organization, Consolidation and Presentation of Financial Statements [Abstract]

4. Collaboration Agreements

GSK

On July 1, 2021, the Company entered into a Collaboration and License Agreement with Glaxo Wellcome UK Limited, a subsidiary of GlaxoSmithKline plc (GSK), pursuant to which the Company and GSK collaborate on the global development and commercialization of progranulin-elevating monoclonal antibodies, including latozinemab (also referred to as AL001), and AL101 (GSK Agreement). The GSK Agreement was made effective on August 17, 2021.

Under the terms of the GSK Agreement, the Company received $700 million in upfront payments, of which $500 million was received in August 2021 and $200 million was received in January 2022. In addition, based on the development and commercialization plan for latozinemab and AL101, the Company may be eligible to receive up to an additional $1.5 billion in clinical development, regulatory, and commercial launch-related milestone payments. In the United States, the Company and GSK will equally share profits and losses from

commercialization of latozinemab and AL101. Outside of the United States, the Company will be eligible for double-digit tiered royalties.

The Company and GSK will jointly develop latozinemab and AL101, with GSK conducting Phase 3 clinical trials for Alzheimer’s disease and Parkinson’s disease and other non-orphan indications. The Company and GSK will share development costs 60% by GSK and 40% by the Company, except that the Company will solely bear the development costs of the initial Phase 2 clinical trials under the development plan, and the parties will share manufacturing development costs equally.

The Company concluded that the GSK Agreement is within the scope of ASC 808, Collaborative Arrangements, as both parties are active participants in the activities and are exposed to significant risks and rewards dependent on the success of the commercialization of AL001 and AL101. Certain elements are required to be accounted for under ASC 606, Revenue From Contracts With Customers, where the counterparty is a customer for a good or service that is a distinct unit of account.

The Company determined that the distinct performance obligations under ASC 606 consisted of: (i) license and know-how to AL001 FTD-GRN, which is currently in Phase 3 clinical development and (ii) the research and development activities, including license rights and know-how, relating to products in Phase 2 or earlier stages of development.

The transaction price at inception and as of December 31, 2022, included fixed consideration consisting of the upfront payments of $700 million. All potential future milestones and other payments were considered constrained at the inception of the GSK Agreement and as of December 31, 2022, since the Company could not conclude it was probable that a significant reversal in the amount of revenue recognized would not occur.

The respective standalone value for each of the performance obligations was allocated to the transaction price. The estimated SSP of each performance obligation was determined using discounted cash flows from the expected commercialization of AL001 and AL101 and estimated research and development costs to be incurred by the Company in the initial Phase 2 clinical trials. The estimate of SSP for each performance obligation reflects management's assumptions, which may include forecasted revenues, development timelines, discount rates, and probabilities of technical and regulatory success. For the license for FTD-GRN, the Company determined that GSK could benefit from the license at the time the license was granted and therefore, the related performance obligation was satisfied at a point in time. For the product candidates in Phase 2 or earlier stages of development, the Company determined that GSK could not benefit from the licenses without the corresponding development services that the Company has committed to perform due the earlier stage of development for these licenses. Except where agreed to otherwise, the Company will perform research and development activities through the end of the initial Phase 2 clinical trials. Revenue will be recognized over time as the research and development activities are performed. The Company will measure progress based on actual costs incurred to date compared to the overall total expected costs to satisfy the performance obligations.

The research and development activities for products in Phase 3 clinical development were determined to be within the scope of ASC 808. Both parties will be active participants in the development, manufacturing, and commercialization of the product and are exposed to significant risks and rewards that are dependent on the commercial success of the products. The Company and GSK participate in profit and loss sharing for each program commensurate with each party's cost-sharing responsibilities during research and development. ASC 808 does not provide recognition and measurement guidance. As such, the Company determined that ASC 730, Research and Development, was appropriate to analogize to based on the nature of the cost-sharing provision of the agreement. The Company has concluded that payments to or reimbursements from GSK related to these services will be accounted for as an increase to or reduction of research and development expenses, respectively.

Collaboration revenue under the GSK Agreement during the year ended December 31, 2022 and 2021, was $62.9 million and $192.1 million, respectively. The deferred revenue related to the GSK Agreement was $444.9 million and $307.9 million as of December 31, 2022 and 2021. The deferred revenue is expected to be recognized over the research and development period of the programs through the completion of initial Phase 2 clinical trials.

Costs associated with co-development activities performed under the agreement are included in research and development expenses in the consolidated statements of operations, with any reimbursement of costs by GSK reflected as a reduction of such expenses. For the year ended December 31, 2022 and 2021, the Company recognized a reduction of research and development expense of $14.7 million and $8.8 million, respectively, under the GSK Agreement.

AbbVie

The Company entered into an agreement in October 2017 with AbbVie Biotechnology, Ltd. (AbbVie) to co-develop antibodies to two program targets in preclinical development (AbbVie Agreement). Under the terms of the AbbVie Agreement, AbbVie made $205.0 million in upfront payments, of which $5.0 million and $200.0 million were received by the Company in October 2017 and January 2018, respectively. The Company was to perform research and development services for the two programs through the end of Phase 2 clinical trials, which were each considered to be separate performance obligations. AbbVie decided to terminate one of the two collaboration programs, the CD33 collaboration program, after AbbVie and Alector collaboratively reviewed next steps for AL003, the asset being developed under that program, and concluded that further development of AL003 was not warranted. AbbVie provided written notice to terminate the CD33 collaboration program on June 30, 2022. The Company will no longer continue development of this program and will not be eligible for any future milestones related to that program from AbbVie. The Company continues to develop the AL002 program under the AbbVie Agreement. AbbVie has the exclusive right to exercise an option under the AbbVie Agreement with the Company for $250.0 million. If AbbVie exercises its option for the AL002 program, AbbVie would take over the development beginning with Phase 3 clinical trials, and the product candidates program costs will be split between the parties. The Company would also share in profits and losses upon commercialization of any products. However, following AbbVie’s exercise of its option for the AL002 program, the Company may opt out of sharing in development costs and profits or losses for that program and instead receive tiered royalties. In February 2023, the Company and AbbVie amended the AbbVie agreement, which will result in the Company receiving a $17.8 million milestone payment for the dosing of the first patient in a long-term extension study. Additionally, under the terms of the AbbVie Agreement, the Company will be eligible to earn up to an additional $225.0 million in milestone payments related to the regulatory approval for up to three indications. The Company assessed its collaboration agreement with AbbVie in the context of the delivery of the research and development services.

The transaction price at inception and as of December 31, 2022, included fixed consideration consisting of the upfront payments of $205 million. All potential future milestones and other payments were considered constrained at the inception of the AbbVie Agreement and as of December 31, 2022, since the Company could not conclude it was probable that a significant reversal in the amount of revenue recognized would not occur.

Collaboration revenue under the AbbVie Agreement during the years ended December 31, 2022, 2021, and 2020 was $70.7 million, $14.9 million, and $21.1 million, respectively. The deferred revenue related to the AbbVie Agreement was $46.7 million and $117.4 million as of December 31, 2022 and 2021, respectively. The deferred revenue is expected to be recognized over the research and development period of the programs through the AL002 program through the completion of Phase 2 clinical trials. For the year ended December 31, 2022, we recorded a net increase to collaboration revenue under the AbbVie Agreement due to changes in estimated costs to satisfy the performance obligations resulting from the termination of the AL003 program, partially offset by increases in total expected costs for the AL002 program.

Innovent

The Company entered into an agreement in March 2020 with Innovent Biologics (Innovent) to license, develop, and commercialize AL008 in China (Innovent Agreement). AL008 is the Company’s novel antibody targeting the CD47-SIRP-alpha pathway, a potent survival pathway co-opted by tumors to evade the innate immune system. Under the terms of the Innovent Agreement, Innovent would pay the Company up to $11.5 million in development milestones, $112.5 million in sales milestones, and future royalties on sales and the Company would retain the rights to develop and commercialize AL008 outside of China. The Company determined there is one performance obligation for the delivery of the license and will recognize revenue when it is probable that there will not be significant reversal of cumulative revenue. Development and sales milestones under the Innovent Agreement were not included in the transaction price, as all these amounts were

fully constrained as of December 31, 2022. As of December 31, 2022, no revenue has been recognized and no payments have been received under the Innovent Agreement.