Collaboration Agreements	6 Months Ended
Jun. 30, 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 AL001 (latozinemab) 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. Under the terms of the GSK Agreement, the Company will lead the global clinical development of latozinemab and AL101, other than with respect to Phase 3 clinical trials for Alzheimer’s disease and Parkinson’s disease and other non-orphan indications, which will be led by GSK. 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. Collaboration revenue under the GSK Agreement during the three and six months ended June 30, 2022 was $21.3 million and $42.4 million, respectively, all of which was included in deferred revenue at the beginning of the period. No revenue was recognized during the three and six months ended June 30, 2021 as the GSK Agreement was not yet effective. The deferred revenue related to the GSK Agreement was $465.4 million and $307.9 million as of June 30, 2022 and December 31, 2021, respectively. 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 condensed consolidated statements of operations, with any reimbursement of costs by GSK reflected as a reduction of such expenses. For the three and six months ended June 30, 2022, the Company recognized a reduction of research and development expense of $3.3 million and $8.8 million, respectively, under the GSK Agreement. No reimbursement of research and development expense was recognized during the three and six months ended June 30, 2021 as the GSK Agreement was not yet effective. 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 paid $205 million in upfront payments, of which $5 million and $200 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. 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. After completion of the Phase 2 clinical trial for AL002, AbbVie will then have the exclusive right to exercise an option under the AbbVie Agreement with the Company for $250 million. If AbbVie exercises its option for the AL002 program, AbbVie would take over the development of the product candidates and 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. Additionally, under the terms of the AbbVie Agreement, the Company will be eligible to earn up to an additional $242.8 million in milestone payments related to the initiation of certain clinical studies and 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. Collaboration revenue under the AbbVie Agreement during the three and six months ended June 30, 2022 was $58.6 million and $61.9 million, respectively, the entire amount of which was included in deferred revenue at the beginning of the period. For the three and six months ended June 30, 2021, collaboration revenue was $6.6 million and $10.7 million, respectively, the entire amount of which was included in deferred revenue at the beginning of the period. The deferred revenue related to the AbbVie Agreement was $55.5 million and $117.4 million as of June 30, 2022 and December 31, 2021, respectively. The deferred revenue is expected to be recognized over the research and development period of the AL002 program through the completion of Phase 2 clinical trials. For the three months ended June 30, 2022, the Company 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 may pay the Company up to $11.5 million in development milestones, $112.5 million in sales milestones, and future royalties on sales. The Company retains the rights to develop and commercialize AL008 outside of China. The Company has 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 have not been included in the transaction price, as all these amounts were fully constrained as of June 30, 2022. As of June 30, 2022, no revenue has been recognized and no payments have been received under the Innovent Agreement.

Collaboration Agreements

6 Months Ended

Jun. 30, 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 AL001 (latozinemab) 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. Under the terms of the GSK Agreement, the Company will lead the global clinical development of latozinemab and AL101, other than with respect to Phase 3 clinical trials for Alzheimer’s disease and Parkinson’s disease and other non-orphan indications, which will be led by GSK. 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.

Collaboration revenue under the GSK Agreement during the three and six months ended June 30, 2022 was $21.3 million and $42.4 million, respectively, all of which was included in deferred revenue at the beginning of the period. No revenue was recognized during the three and six months ended June 30, 2021 as the GSK Agreement was not yet effective. The deferred revenue related to the GSK Agreement was $465.4 million and $307.9 million as of June 30, 2022 and December 31, 2021, respectively. 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 condensed consolidated statements of operations, with any reimbursement of costs by GSK reflected as a reduction of such expenses. For the three and six months ended June 30, 2022, the Company recognized a reduction of research and development expense of $3.3 million and $8.8 million, respectively, under the GSK Agreement. No reimbursement of research and development expense was recognized during the three and six months ended June 30, 2021 as the GSK Agreement was not yet effective.

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 paid $205 million in upfront payments, of which $5 million and $200 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. 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. After completion of the Phase 2 clinical trial for AL002, AbbVie will then have the exclusive right to exercise an option under the AbbVie Agreement with the Company for $250 million. If AbbVie exercises its option for the AL002 program, AbbVie would take over the development of the product candidates and 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. Additionally, under the terms of the AbbVie Agreement, the Company will be eligible to earn up to an additional $242.8 million in milestone payments related to the initiation of certain clinical studies and 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.

Collaboration revenue under the AbbVie Agreement during the three and six months ended June 30, 2022 was $58.6 million and $61.9 million, respectively, the entire amount of which was included in deferred revenue at the beginning of the period. For the three and six months ended June 30, 2021, collaboration revenue was $6.6 million and $10.7 million, respectively, the entire amount of which was included in deferred revenue at the beginning of the period. The deferred revenue related to the AbbVie Agreement was $55.5 million and $117.4 million as of June 30, 2022 and December 31, 2021, respectively. The deferred revenue is expected to be recognized over the research and development period of the AL002 program through the completion of Phase 2 clinical trials. For the three months ended June 30, 2022, the Company 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 may pay the Company up to $11.5 million in development milestones, $112.5 million in sales milestones, and future royalties on sales. The Company retains the rights to develop and commercialize AL008 outside of China. The Company has 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 have not been included in the transaction price, as all these amounts were fully constrained as of June 30, 2022. As of June 30, 2022, no revenue has been recognized and no payments have been received under the Innovent Agreement.